Right ventricle (RV) is considered a neglected chamber in cardiology and knowledge about its role in cardiac function was mostly focused on ventricular interdependence. However, progress on the understanding of myocardium diseases primarily involving the RV led to a better comprehension of its role in health and disease. In Chagas disease (CD), there is direct evidence from both basic and clinical research of profound structural RV abnormalities. However, clinical detection of these abnormalities is hindered by technical limitations of imaging diagnostic tools. Echocardiography has been a widespread and low-cost option for the study of patients with CD but, when applied to the RV assessment, faces difficulties such as the absence of a geometrical shape to represent this cavity. More recently, the technique has evolved to a focused guided RV imaging and myocardial deformation analysis. Also, cardiac magnetic resonance (CMR) has been introduced as a gold standard method to evaluate RV cavity volumes. CMR advantages include precise quantitative analyses of both LV and RV volumes and its ability to perform myocardium tissue characterization to identify areas of scar and edema. Evolution of these cardiac diagnostic techniques opened a new path to explore the pathophysiology of RV dysfunction in CD. However, because the right and left ventricles are aligned in series and mechanically coupled, a perturbation in the mechanical events of one ventricle will influence the behavior of the other ventricle, and in nonsteady state conditions the output of the two ventricles may not be balanced. Eventually, however, a steady state of balanced outputs must occur if pulmonary or systemic venous congestion is to be avoided. Historically, physiology concepts about heart function considered the right ventricle as a kind of almost perfunctory chamber, although knowledge about ventricle interdependence was well recognized decades ago . Weber eDiastolic interplay between ventricles is easy readily understandable, mainly considering the function of pericardium as the common covering layer for both ventricles. However, although the presence of pericardium accentuates this interaction, animal experimental models with the pericardium excised showed that the diastolic interplay was still present . There iBased on these physiologic aspects and adding to the fact that many of the studies were designed on a volume-pressure relation basis, it is possible to understand why cardiology science neglected the RV as a “secondary chamber” or a “passing chamber” . Nonethe T. cruzi infection; and, finally, because there is a proportion of patients with early and isolated right ventricle dysfunction when evaluated by different cardiac image methods [There is evidence that CD causes a peculiar right ventricle involvement first because evolution of the disease to heart failure usually includes prominent right heart failure symptoms in absence of or with only mild pulmonary congestion , 8; seco methods , 10.However, exploring the right ventricle with imaging diagnostic tools is still a challenge. The accumulated evidence about ventricular systolic function in most diseases is derived from echocardiography. Two-dimensional echocardiography needs geometrical assumptions to estimate ventricular volumes and the right ventricle simply does not have a mathematically defined geometrical form.This review explores the right ventricle anatomic and functional involvement in Chagas cardiomyopathy (CC) while highlighting the contribution of cardiac imaging diagnostic methods in the field.CD was recognized by WHO as one of the world's 13 most neglected tropical diseases with a high prevalence of individuals at risk of infection in South and Central America and with the highest rates of mortality between all neglected diseases . Althoug T. cruzi protozoan infection that leads, in most cases, to a myocardial chronic inflammatory response [CD is caused by theresponse . Myocardresponse  which reresponse . Histoloresponse , 19 , no clinical manifestations of the RV functional impairment would be detectable. However, within this setting of RV early impairment, when the left ventricle dysfunction occurs causing the rise in pulmonary vascular resistance, compensatory mechanisms of the RV achieve their limits. From this moment on, right-sided symptoms and signs may thus dominate the clinical expression of heart failure .Mady et al., who had already shown right ventricle histologic abnormalities in 60% of patients with the indeterminate form of CD , also st speckle tracking as a new methodology echocardiography tool with potential to measure myocardium deformity, Barbosa et al. [Several years later, various studies using echocardiography as a noninvasive tool to assess RV geometry and function showed mixed results in diverse groups of patients with various forms of CD. Nunes et al., in 2004, using a nonquantitative echocardiography analysis, reported not being able to detect isolated RV dysfunction in a group of subjects in both early and later (28% of patients) stages of CC . Howevera et al.  reportedRecently, Moreira et al. demonstrated, in a comparative investigation using cardiac magnetic resonance as a reference method, that all conventional echocardiographic parameters for right ventricular assessment studied, including TAPSE, S′ of tricuspid annulus, fractional area change, and right ventricular index of myocardial performance, have a very low sensitivity to detect right ventricular systolic dysfunction in patients with CD. In contrast, analysis of right ventricular deformation by using two-dimensional speckle tracking echocardiography yielded a high ability to differentiate patients with from those without RV systolic dysfunction. The right ventricular free wall strain had a remarkably higher sensitivity in comparison with traditional echocardiographic parameters to identify RV dysfunction .Cardiac magnetic resonance methods have inherent advantages for the evaluation of RVEF, since volumes can be directly measured instead of being geometrically extrapolated . StudyinBased on all exposed data, we can conclude that detection of incipient right ventricle dysfunction is still dependent on technical evolution of cardiac diagnosis image tools. And this concept probably can be extrapolated to any disease with a potential to primarily involve the right ventricular myocardium.The prognostic impact of RV dysfunction in CD is not yet completely explored. Nunes et al. evaluated 158 subjects, all with left ventricle dilatation and dysfunction during a follow-up of 34 ± 23 months. The RV dysfunction parameter evaluated, Tei index of ventricular performance, was a predictor of mortality . These d T. cruzi chronically infected populations from 15% to 40% [ T. cruzi [CD frequently affects the heart conduction system and the most frequently found conduction abnormality is right bundle branch block (RBBB), often associated with left anterior fascicle bundle branch block (LAFB) . Prevale% to 40% , 57. AmoT. cruzi . HistoloT. cruzi .It is not clear if RBBB is really a primarily manifestation or if it is secondary to myocardial damage extending to conduction system. Also, the role of RBBB in physiopathology of CD is not well understood. One previous study showed that, in a cohort of asymptomatic patients with RBBB, patients with CD have a worse prognostic regarding cardiac sudden death when compared to other patients with RBBB and no CD . AlthougThe real contribution of this electrical disturbance to RV dysfunction has not been investigated. This contrasts with the conspicuous evidence that left bundle branch block (LBBB) is associated with left ventricle dysfunction . AlthougEvaluation of right ventricle anatomy and function with echocardiography is always challenging. Right ventricle unique macroscopic morphology, which includes an inflow and outflow regions and the main cavity, cannot be represented by a simple mathematical geometric model. Because of this, geometric extrapolations to estimate chamber volumes, so useful for bidimensional echocardiographic assessment of the LV, cannot be applied in the case of the RV . AlthougdP/dT from systolic time of the tricuspid regurgitation Doppler spectrum [Recognizing these problems, a guide on how to measure right ventricle geometry and function with echocardiography was released in 2010 and was further updated and included in an echocardiography chamber quantification recommendation in 2015 , 66. Thespectrum  (Figure S′, TAPSE, and MPI to detect right ventricular dysfunction in more advanced stages of disease and symptomatic patients [Considering the overall neglectful cardiology approach to the right ventricle, it is understandable why the same gaps of knowledge also exist for CD studies. Acquatella, in an outstanding publication survey in 2007, extensively reviewed echo contributions to the field of CD without fully addressing the mixed results of studies of echocardiographic evaluation of RV in CD . Despitepatients . Some pupatients , 70. Howpatients . Also, upatients .Speckle tracking is a relatively new echocardiography tool and discussion about its methodology advantage over other approaches is still a topic of interest [interest . With thinterest , 73 and interest . Normaliinterest . speckle tracking in CD were focused on left ventricle analysis assessment [Most of published data usingsessment , 75–77. sessment , 75 nor sessment  in specksessment , since t Speckle tracking is a promising tool to assess RV dysfunction in this disease overcoming the lack of sensitivity of conventional 2D and Doppler measurements of function.In summary, echocardiography can be used to detect RV dysfunction in CD but with some inherent methodological limitations.With its inherent capability for the direct measurement of chamber volumes and the calculation of biventricular ejection fraction without geometric extrapolations, CMR is clearly a more advantageous method than echocardiography for that purpose. In this regard, the method is already considered a gold standard of ventricle volumes quantification . This ha T. cruzi chronically infected subjects with preserved left ventricular ejection fraction [The utility of CMR in CD was first demonstrated for the study of left ventricle systolic function and the detection of left ventricle myocardial fibrous tissue and its significance –82. As mfraction .Therefore, even considering the intrinsic difficulties in using CMR in clinical settings, most of them related to cost and availability, especially curtailed by scarce resources in endemic regions of CD, there is now a definite drive for the clinical approach with CMR to evaluate early biventricular damage in CD. T. cruzi infection that closely mimics human chronic Chagas, with the advantage of a relatively short 8–10 months of evolution to chronic phase, has allowed the integration of echocardiography analyses with anatomopathologic findings [ speckle tracking quantification can be a useful tool, despite its reproducibility still being a controversy theme.Recent research using a mammalian experimental model offindings , 84. Somfindings . This isBased on the concepts described along this review of CC being an immune-inflammatory disease affecting both the left and the right ventricles, CMR has the potential to detect not only fibrosis but also myocardium edema and inflammation, in order to further extend seeking for detection of early myocardial damage. CMR techniques as T2 sequences are recently emerging in diverse scenarios of myocardial diseases, including infarction and acute myocarditis , and theRight ventricle role in cardiovascular physiology and pathology has been historically neglected. Cardiology science is still “on the way” to understand the right ventricle role into cardiovascular physiology and to detect structural and function abnormalities in this geometrically complex chamber.Different from other dilated cardiomyopathies, CD has a unique characteristic of frequently early and progressive damage involving cell death, inflammation, and fibrosis not only in the left but also in the right ventricle myocardium. Evolution of cardiac imaging modalities added current analyses of myocardial deformation by speckle tracking echocardiography and both chamber volumetric evaluation and tissue characterization using cardiac magnetic resonance. These novel technologies offer new perspective to study right ventricular involvement and to understand the associated aspects of CD progression in terms of malignant arrhythmias and heart failure. Sudden death, the most frequent mode of death in patients with CC, occurring even when there is preserved global LV systolic function, should be especially amenable to investigations using CMR.


Coarctation of the aorta (CoA) affects about 4 out of every 10,000 babies born and requires lifelong follow-up. Even after successful early repair, late cardiovascular (CV) complications arise. In adult patients, left ventricular remodeling (LVR) patterns can predict CV risk. However, few studies on LVR of CoA patients exist due to lack of detailed geometric models. The Cardiac Atlas Project (CAP), a worldwide consortium for pooling standardized analyses of cardiac images for mapping heart shape and motion, provides a unique opportunity to study CoA cardiac remodeling. This study compares LV shape in a sample of CoA patients pre- and post-stent to normal patients from the CAP with the goal of developing model-based predictions of LVR to guide clinical management.Cardiac magnetic resonance images (CMRI) and clinical data of five patients (Ages: 8-24 yrs.) with native and re-coarctation of the aorta were collected with IRB approval. All study patients were potential candidates for stent implantation. CMRI 1-2yrs. post-stent are currently available for four patients.Patient-specific geometric models were built from CMRI using finite element guide-point modeling software . Shape modes at end-systole (ES) and end-diastole (ED) were derived using principal component analysis (PCA) of a population (n = 1991) of asymptomatic volunteers from the CAP. PC scores describing the deviation of each CoA model from the asymptomatic PCA model distribution at ED and ES for various shape modes were calculated.Figure Preliminary results with a small sample size comparing LV geometry of CoA patients against an atlas-based population of controls show LV shape characteristics that are similar to the normal LV. Notable characteristics post-stent include change in wall thickness and mitral valve orientation which reflect remodeling of the ventricle. Detailed quantification of cardiac shape can improve our understanding of the adverse effects of remodeling and, in combination with future patient-specific biomechanics models, advance the potential for early recognition of remodeling patterns to guide timely clinical management.


Mechanical ventilation (MV) is a life-saving intervention for respiratory failure, including decompensated congestive heart failure. MV can reduce ventricular preload and afterload, decrease extra-vascular lung water, and decrease the work of breathing in heart failure. The advantages of positive pressure ventilation must be balanced with potential harm from MV: volutrauma, hyperoxia-induced injury, and difficulty assessing readiness for liberation. In this review, we will focus on cardiac, pulmonary, and broader effects of MV on patients with decompensated HF, focusing on practical considerations for management and supporting evidence. Heart failure (HF) affects over 5 million Americans and is the single most expensive diagnosis in the U.S. health system, accounting for 5% of the total U.S. healthcare budget ,2. In thMV is a life-saving intervention for decompensated congestive heart failure, however, management must be guided by a knowledge of both the advantages and dangers of invasive MV in order to realize its benefits and avoid adverse effects. MV should be viewed as a tool that, if appropriately used, is a key part of the armamentarium for managing acute decompensations .When utilized correctly in decompensated HF, the effects of MV—specifically positive end expiratory pressure (PEEP), inspiratory support, and supplemental oxygen—can provide substantial advantages in left ventricular (LV) dysfunction and recovery. In decompensated HF, MV provides numerous benefits that include decreasing cardiac afterload leading to decreased left ventricular oxygen demand and increased cardiac output, decreasing the work of breathing which decreases cardiac output requirements, improving hypoxia-induced pulmonary vascular constriction, and improving oxygenation of the myocardium  6]..6].The use of PEEP has a number of specific benefits in the setting of decompensated HF but must be used cautiously in selected circumstances. Increased intrathoracic pressure from PEEP decreases venous return and lowers preload. Mechanistically, the PEEP-mediated increase in intrathoracic pressure is transmitted to the right atrium, increasing right atrial pressure and decreasing the gradient for venous return from outside the thorax, which results in a drop in right ventricular (RV) preload and a corresponding decrease in LV preload, left atrial pressure, and pulmonary venous congestion . PEEP ha2O of PEEP were more likely to survive to discharge, had improved hemodynamic indices, and required lower doses of dobutamine than those receiving oxygen supplementation alone [PEEP can also augment cardiac output by decreasing LV afterload. LV afterload is proportional to LV end-diastolic volume and LV systolic transmural pressure . LV syston alone . The poton alone .Despite evidence of the potential benefits of PEEP in patients with decompensated HF, the use of PEEP needs to be weighed against potential harms. Increasing PEEP in patients with low end-diastolic volume can decrease venous return, resulting in inadequate preload, reduced CO, and end-organ hypoperfusion . High le2O with incremental increases of 2–3 cm of H2O every 15–30 min as needed, guided by careful monitoring of hemodynamics and indices of end-organ perfusion in order to identify the optimal, non-injurious PEEP level.In the early years of clinical practice with mechanical ventilation, PEEP was believed to have a negative effect on cardiac output and tissue perfusion based on data extrapolated from animal models without cardiac disease . Over th2O of pressure support resulting in a decrease of over 30% in the work of breathing [The inspiratory support offered by MV is an often-overlooked advantage in patients with decompensated heart failure and cardiogenic chock in particular. When patients are in respiratory distress, respiratory muscles can require as much as 16% of the cardiac output . FurtherCardiogenic pulmonary edema develops when the hydrostatic pressure gradient increases between the pulmonary capillaries and surrounding interstitial space, leading to fluid accumulating in the extravascular space. With elevated interstitial hydrostatic pressure, fluid enters the alveoli ,18. IncrWhile there have been limited studies specifically addressing the selection of tidal volumes for patients with decompensated HF receiving MV, numerous studies have shown the clinical benefits of low tidal volume ventilation between 6–8 mL per kilogram of predicted body weight (PBW) in various disease states including the acute respiratory distress syndrome (ARDS), intraabdominal surgery, high risk cardiac surgeries, and trauma ,21,22,232O limits the risk of barotrauma, which can result in pneumothorax and pneumomediastinum, and limits excessive alveolar distention, which can lead to ventilator-induced lung injury [Transpulmonary pressure (TPP) is defined as the alveolar pressure minus the intrapleural pressure, and represents the alveolar distending pressure that is “felt” by the lung . Since ig injury ,24.Alveolar hypoxia and acidemia reduce nitric oxide production, leading to pulmonary vasoconstriction . In heal2 (FiO2), is the fastest intervention to improve acute hypoxemia. Similar to the management of PEEP and tidal volume, excessive supplemental oxygen can lead to adverse hemodynamic consequences including ventilation-perfusion mismatch, impaired cardiac relaxation, and increased LV filling pressures in patients with HF independent of their ventilation and sympathetic activity [2 in excess of 50% can lead to oxygen free radical formation, which has been shown to worsen cardiac apoptosis, lead to intracellular calcium overload, and cause cardiac hypertrophy [2 above 50% has been shown to cause coronary vasoconstriction, decreased stroke volume and cardiac output, and foci of myocardial necrosis [2 should ideally be ≤50% to avoid free radical damage , recently proven to be in humans, limits excessive tidal volumes . These sChronic heart failure is characterized by a net increase in sympathetic nerve activity from numerous contributing factors (both advantageous and deleterious), the predominant contributor being cardiopulmonary baroreflex mechanisms ,41. In pCheyne-Stokes respiration (CSR) is common in heart failure with reduced ejection fraction (HFrEF) with an incidence of 25%–40%, correlating with disease severity . CSR is p < 0.001) [Data regarding the management of mechanical ventilation in CSR are all derived from studies of non-invasive positive pressure ventilation (NIPPV). Despite a number of randomized, controlled trials, however, the role of non-invasive mechanical ventilation in the management of CSR remains unclear. The CANPAP randomized, controlled trial of CPAP in patients with HFrEF and central sleep apnea demonstrated improved left ventricular ejection fraction (2.2% ± 5.4%), improved nocturnal oxygenation, and lower endogenous norepinephrine levels, but no change in survival . Adaptiv< 0.001) . The SAV< 0.001) . More re< 0.001) . The SER< 0.001) . Taken tFor patients with CSR requiring invasive MV, there is a paucity of data to guide care. Extrapolating the logic behind ASV to invasive MV management, it is our recommendation to use modes of MV that provide a consistent level of inspiratory support . Dynamic pressure-targeted modes such as proportional assist ventilation, volume support, and pressure-regulated volume control, should generally be avoided in patients with CSR since constantly changing respiratory drive may result in inappropriate ventilator settings and patient-ventilator asynchrony. Spontaneous breathing trials may be stopped prematurely due to apnea; therefore, it is our recommendation that apnea alarm thresholds be elongated, assuming no associated hemodynamic instability. While the optimal management of mechanical ventilation in CSR remains unclear, it is important to remember that treatment of heart failure with standard medical therapies will often improve CSR.2O and pressure support ≤8 CM H2O). While the latter can appear to be a trivial amount of support, in patients with decompensated HF even small amounts of pressure support and PEEP can have significant hemodynamic effects. Removal of seemingly minimal amounts of PEEP can result in rapid deterioration of LV function leading to pulmonary edema [2O of pressure support decreases inspiratory work by 31% to 38%; 10 cm H2O of pressure support decreases work by 46% to 60% [While the rapid shallow breathing index and spontaneous breathing trials (SBT) are the most ubiquitous indices to assess readiness for extubation, not all SBTs are performed with the same ventilator settings. In clinical practice, there is a spectrum of PEEP and pressure support levels used while performing SBTs; from T-piece trials  to “minimal ventilator settings”  can be applied prophylactically. Nava et al. found amongst patients at risk of re-intubation, including those with heart failure, that the prophylactic use of NIPPV for at least 8 h per day in the first 48 h following extubation lead to a 10% relative risk reduction in ICU mortality, likely mediated by a reduction in the need of reintubation . Ferrer It is the authors’ opinion that patients requiring inotropic support in whom liberation from mechanical ventilation is being considered merit particularly close attention due to restricted ability to increase cardiac output under physiologic stress. For this reason, we frequently perform spontaneous breathing trials in patients with marginal cardiac function without any supplemental support  to assess the ability to tolerate fully unsupported breathing. Careful optimization of preload, afterload, and inotropic support (in selected patients) both before and after extubation is paramount to preventing re-intubation.The hemodynamic benefits of MV are often-overlooked in patients with decompensated congestive heart failure and cardiogenic shock in particular. Favorable effects of MV in acute decompensated HF include reducing ventricular preload and afterload, decreasing extra-vascular lung water, and decreasing the work of breathing and its associated cardiac output requirements. The appropriate use of MV should be seen as an important adjunctive therapy in the initial stabilization and management of patients with decompensated HF and acute respiratory failure. Patients with acute decompensated HF require special attention to ventilator weaning and liberation from MV since HF is well recognized as a risk factor for extubation failure and the need for re-intubation. Spontaneous breathing trials without ventilator support  may reveal the need for further medical optimization of preload, afterload, and contractility prior to planned extubation since removal of even a seemingly trivial amount of support can result in hemodynamic instability, flash pulmonary edema, and rapid decompensation. Prophylactic use of non-invasive positive pressure ventilation immediately upon extubation may prevent re-intubation in patients with marginal cardiac function but non-invasive ventilation should not be thought of as a rescue therapy for patients who develop acute respiratory failure after extubation since this practice has been associated with increased mortality compared to medical therapy alone with prompt re-intubation if needed. When carefully applied, both invasive mechanical ventilation and non-invasive positive pressure ventilation should be considered important tools in the successful management of respiratory failure in patients with acute decompensated HF.


A growing proportion of heart failure (HF) patients present with impairments in both ventricles. Experimental pressure-overload  induces left ventricle (LV) hypertrophy and failure, as well as right ventricle (RV) dysfunction. However, little is known about the coordinated progression of biventricular dysfunction that occurs in TAC. Here we investigated the time course of systolic and diastolic function in both the LV and RV concurrently to improve our understanding of the chronology of events in TAC. Hemodynamic, histological, and morphometric assessments were obtained from the LV and RV at 2, 4, 9, and 18 weeks post-surgery.Results: Systolic pressures peaked in both ventricles at 4 weeks, thereafter steadily declining in the LV, while remaining elevated in the RV. The LV and RV followed different structural and functional timelines, suggesting the patterns in one ventricle are independent from the opposing ventricle. RV hypertrophy/fibrosis and pulmonary arterial remodeling confirmed a progressive right-sided pathology. We further identified both compensation and decompensation in the LV with persistent concentric hypertrophy in both phases. Finally, diastolic impairments in both ventricles manifested as an intricate progression of multiple parameters that were not in agreement until overt systolic failure was evident.Conclusion: We establish pulmonary hypertension was secondary to LV dysfunction, confirming TAC is a model of type II pulmonary hypertension. This study also challenges some common assumptions in experimental HF  while addressing a knowledge gap with respect to temporality of RV remodeling in pressure-overload. Heart failure (HF), a chronic condition characterized by the inability of the heart to meet the metabolic demands of the body, is an increasing epidemic and a leading cause of mortality in the developed world . As the Transverse aortic constriction (TAC) was developed to investigate the left ventricle (LV) response to pressure-overload  and is smin, filling pressures, Tau) agree over time in TAC? We hypothesize that different indices of diastolic function will progress independently given the complexity of cardiac diastole and, likely, the different aspects captured by each parameter.Diastolic dysfunction is growing concern requiring more research, given that it is more prevalent than systolic dysfunction in HF patients , the genThe salient findings in this study are: (1) Pulmonary hypertension was secondary to the increase in LV filling pressure and dysfunction, and RV and pulmonary vasculature remodeling was temporally distinct from the LV. (2) Determining the severity of diastolic dysfunction in either ventricle over time was complex, given that diastolic parameters were not in agreement until overt systolic dysfunction was apparent. And (3) the time course of structural and kinetic changes in both ventricles was interesting: interstitial fibrosis did not correlate with filling pressures in either ventricle, LV pressures did not predict RV pressures, and hypertrophy in the LV and RV had both early and late stage phenotypes that were not predictable from prevailing hemodynamics. Together, this study improves our understanding of the biventricular response to pressure-overload and firmly establishes TAC as a model of type II pulmonary hypertension.ad libitum. This study was approved by the Animal Care Committee at the University of Guelph and all experiments were carried out in accordance with the guidelines from the Canadian Council on Animal Care.Briefly, 9-week-old male (32–40 g) CD-1 mice , were anesthetized with an isoflurane/oxygen mix (2%:100%), intubated and connected to a ventilator (Harvard Apparatus). Mice were ventilated at 200 breaths per minute at 300 μL per breath. TAC was done as previously described . BrieflyMice were anesthetized with an isoflurane/oxygen mix (2%/100%). Echocardiography was performed using the Vevo2100 system  with the 40 MHz MS550D ultrasound transducer. Mice were kept at 37°C throughout data collection using a TH-5 rectal probe thermometer . Acquired M-mode images were analyzed with the LV-trace function from the cardiac package , and data was obtained over at least 5 heart beats as previously described . All mea® analytic software . Data sets were analyzed with the removal of respiration artifacts. The presence of pulmonary hypertension was determined using the 99th percentile upper reference limit . Thus, 32.5 mmHg was deemed the physiological threshold for pulmonary hypertension in our model. Animals designated for morphometric analysis had organs removed, cleaned and weighed. Animals designated for histological analysis were exsanguinated and 10 mL of 1x PBS, 10 mL of 0.5 mol L-1 KCl, and 10 mL of 10% buffered formalin  were perfused through the right carotid artery. Tissues were harvested, stored in 10% buffered formalin for 24 h, and then transferred to 70% ethanol until tissue processing.Mice were sacrificed at 2, 4, 9, or 18 weeks after TAC or sham surgery. Again, an isoflurane/oxygen mix (2%:100%) was used, and again mice were kept at 37°C while a 1.2F catheter  was inserted into the RV via the right jugular and into the LV via the right carotid. Hemodynamic signals were digitized at a sampling rate of 2 kHz and recorded using iWorxCross sectional slices (∼5 μm) were obtained from the mid papillary region of the heart. Paraffin embedded sections were stained with either Picro-Sirius Red , to visualize interstitial fibrosis (staining cytoplasm yellow and collagen red), or Wheat Germ (Sigma Aldrich) to assess cardiomyocyte cross-sectional area (CSA) (staining cell borders green). Images were acquired using an Olympus FSX 100 light microscope and analyzed using Cell Sense software . CSA was quantified only from cardiomyocytes with centralized nuclei. For analysis of lung tissue, fresh Verhoff Van Geison stain was prepared with reagents obtained from VWR . This stains elastic fibers and nuclei purple/black, collagen fibers red and cytoplasm yellow. The medial thickness of muscularized arteries was expressed as a percentage of external medial diameter. Arteries with internal diameters < 35 μm were selected for quantifying the ratio of muscularized to non-muscularized arteries .t-test. A one-way ANOVA (Tukeys post hoc) was used to determine differences within one group over 18 weeks as all measures were terminal. Differences between sequential time-points were subsequently determined using a two-tailed Students t-test. Regression analyses were done with Prism 6.0. The threshold for significance was p < 0.05 in all cases unless otherwise specified.All results are expressed as means ± SE unless otherwise indicated. Statistical analysis was performed using Prism (Graphpad Software Inc.). Statistical significance between sham and TAC mice at individual time-points was determined using the two-tailed Students Figure 1 and Table 1 .To account for changes in function as the mice aged, TAC’s were compared to age-matched surgical shams at all time-points. Representative tracings and a summary of invasive hemodynamic function over 18 weeks of TAC are presented in Figure 1C) peaked at 4 weeks before progressively declining toward sham values by 18 weeks. RV pressure  peaked at 4 weeks, but unlike the LVP, plateaued from 9 to 18 weeks. Of importance for the chronology of this model, pulmonary hypertension did not develop until 4 weeks. Only 11% (1/9) of TAC mice at 2 weeks had pulmonary hypertension. By 4 weeks, incidence of pulmonary hypertension rose to 90% (9/10) and was 75% thereafter (16/21).LV pressure  was used as an index of contractility . LV dP/dtmax initially decreased at 2 weeks before rebounding by 4 weeks and progressively declining thereafter. In the RV, dP/dtmax was unchanged until increasing at 4 weeks before also declining thereafter.To evaluate systolic function, the first positive derivative of ventricular pressure (dP/dtmin), end diastolic pressure (EDP) and two methods to calculate the relaxation time constant  . LV EDP increased ∼400% by 2 weeks and plateaued thereafter . LV dP/dtmin followed the same trend as LV dP/dtmax, initially reduced at 2 weeks, normalizing by 4 weeks and then progressively declining out to 18 weeks . LV TauW increased only by 18 weeks  while TauG was elevated both at 2 and 18 weeks . In the RV, EDP initially increased by 4 weeks before partially returning toward sham levels at an elevated plateau between 9 and 18 weeks . RV dP/dtmin followed the same pattern as RV dP/dtmax, increasing at 4 weeks before declining out to 18 weeks . RV TauG increased at 2 weeks  while TauW increased at 4 weeks ; both stayed elevated from sham thereafter.To assess diastolic dysfunction, we used three different indices: the first negative derivative of ventricular pressure . Interestingly, while LV dP/dtmax was stable (changing by <10% over 18 weeks), RV dP/dtmax increased ∼30% between 2 and 9 weeks . In the LV, most measures of diastolic function declined by 18 weeks , yet TauW remained unchanged (Table 2). Alternatively, in the RV, measures of diastolic function either improved (dP/dtmin increased by ∼40%) or were unchanged .In sham mice, LV and RV pressure, as well as systolic and diastolic function also changed over 18 weeks. LVP increased by ∼20%, while RVP increased by ∼10% . In the LV, interstitial fibrosis progressively increased over 18 weeks, initially increasing ∼8 fold by 2 weeks with a further 50% increase out to 18 weeks . In the RV, interstitial fibrosis increased linearly ∼10 fold by 4 weeks, stabilizing thereafter .Elevations in EDP are sometimes reconciled as the product of fibrotic remodeling. To investigate this relationship over time in our model, histological sections of the ventricles were stained with PSR  or RV . Of an interesting note was that interstitial fibrosis increased ∼500% in the RV by 2 weeks without a concurrent change in RV EDP.Regression did not find a significant non-zero relationship between EDP and fibrosis over time in either the LV  and RV . No parameter consistently correlated over time. At best, in the RV only, there was a dichotomy between early and late fibrosis and diastolic dysfunction.To investigate if fibrosis correlated with any other parameter of diastolic function, we compared the relationship between fibrosis and dP/dtFigure 3). Representative H&E (top panel) and PSR (bottom panels) cross-sectional images of the heart are presented in Figure 4A. Whole heart hypertrophy increased steadily , culminating in significantly larger hearts by 18 weeks of TAC . To evaluate chamber-specific hypertrophy, atrial, LV, RV and septal weights were normalized to TL. The atrial/TL and LV/TL ratio increased steadily across all time points. RV/TL did not increase until 4 weeks of TAC  while the septum/TL ratio increased to 4 weeks where it plateaued and increased proportional to sham out to 18 weeks . Expanded morphometrics are presented in Table 3 (TAC) and Table 4 (sham).To investigate the hypertrophic response following LV pressure-overload, whole hearts  were weighed and normalized to tibial length (TL). Weights were normalized to TL as increasing BW skewed the HW/BW ratio in sham mice, while HW/TL in the same mice was stable across normal growth . LV CSA increased progressively over 18 weeks, while RV CSA only increased between 2 and 4 weeks, remaining stable thereafter . The linear increase in LV weight and LV CSA over 18 weeks suggested the rate of hypertrophy was constant and likely (predominantly) concentric . In contrast, the pattern in the RV had two parts. Initially (0–4 weeks), RV CSA and weight increased linearly . Between 4 and 18 weeks, however, RV weight continued to increase while RV CSA plateaued. While this increased weight could be attributed to extracellular proteins or cardiomyocyte hyperplasia, RV fibrosis was static between 4 and 18 weeks  and, adult cardiomyocyte hyperplasia is accepted to be low to negligible. This suggested the weight was coming from an increase in cardiomyocyte cell length .To quantify concentric hypertrophy, cardiomyocyte CSA was assessed in both the LV and RV  began at 4 weeks and progressed to 18 weeks . Cardiac output decreased by 2 weeks and remained stable until 9 weeks before decreasing further by 18 weeks . Ejection fraction, a common variable used to clinically grade LV function, followed the same pattern as cardiac output with the secondary decline occurring between 9 and 18 weeks . Complete echocardiographic data from sham and TAC mice is summarized in Table 5.Representative M-mode images from the LV of sham and TAC mice are profiled in Figure 7A). We found increased large-vessel wall thickness by 2 weeks with a neomuscularization of the smaller vessels by 4 weeks; both continuously increased thereafter . By 9 weeks, this was associated with an increased total lung weight without evidence of pulmonary edema . Pulmonary vascular resistance, calculated using the formula PVR = (RVP–LV EDP)/cardiac output), was reduced at 2 weeks, before peaking at 4 weeks and remaining elevated thereafter .To confirm the increase in RVP was pathological, we looked for evidence of pulmonary vascular remodeling within the pulmonary circulation by histology (min) following a different pattern over time. And finally, fibrosis did not correlate with diastolic pressure in either ventricle over time, calling into question how fibrosis per se is related to elevations in EDP.This study is the first to report a longitudinal, biventricular evaluation of cardiac function and morphology in the murine pressure-overload model. Here we mapped the pathophysiological development of type II pulmonary hypertension, pulmonary vascular remodeling and RV dysfunction in TAC for the first time. There were two phases of function, compensatory and decompensatory. In the compensatory phase, both the LV and RV remodeled concentrically in line with increased pressure. During decompensation, the LV continued to hypertrophy concentrically despite declining pressure, while in the RV the data suggested a shift to eccentric hypertrophy. We also demonstrated that no one parameter was sufficient to explain diastolic function with each index  impacts both the amount of hypertrophy and rate of dilation. Smaller gauges [i.e., 24-gauge , 25-gaugInterstitial fibrosis correlates with a stiffening of the LV wall, which impairs ventricular relaxation and contributes (among other things) to increased passive filling pressures (EDP) . IncreasIn shams, we report appreciable changes in cardiac structure and function over the 18 week study period. This was especially true in the RV, where between 2 and 9 weeks invasive measures of contractility and relaxation increased by ∼33%. In the same time frame, the change in LV function was <10%. This suggests the healthy RV may reach functional maturity in a different timeframe than the LV. Importantly, evidence of contractile dysfunction in the TAC RV was only significant by 18 weeks because of the increase in RV function in aged-matched shams. This demonstrates the importance of mapping structure and function in shams/controls, particularly in longitudinal studies where early time points may misrepresent the mature phenotype.Type-II pulmonary hypertension is the most prevalent form of pulmonary hypertension . ReporteRemodeling patterns in the LV cannot be applied to the RV; the RV is developmentally , physiolFigure 8). This may be due to extensive recruitment and distension of pulmonary capillaries to reduce pulmonary vascular resistance in early situations of elevated EDP.The RV is, at least in part, hemodynamically dependent on the LV . One exaFigure 9).Finally, in light of the varying patterns between the LV and RV with regards to pressure and hypertrophy, we introduce an updated depiction of hypertrophy progression in pressure-overload . This differs from the clinical reliance on indirect surrogate measures . Of concern is whether the surrogate measurements remain in agreement with the fundamental pathophysiology. We found over time, diastolic function was not easily reconciled by any one parameter, suggesting diastolic dysfunction is more a spectrum of impairments than a singular entity.The concept of “diastolic dysfunction,” which grew out of clinical observation, is cumbersome to diagnose and a validated gold standard is missing. Indeed, what we define as dysfunction is only in terms of referencing ‘normal’ function, which is dynamic as the cardiovascular system develops and ages. In experimental models, the standard is to measure diastolic function invasively  detected diastolic impairments by 2 weeks while Tau Weiss (TauW) was unchanged. The discrepancy between Tau measures may exist because TauW (approximated in isolated hearts) assumes an independence of Tau from volume loading and changes in EDP   . Given tmin, and TauG decreased from pre-surgical values). This is consistent with human data where diastolic function is more fragile with aging than systolic function (Additionally, it was unexpected that in sham mice, while systolic function remained stable, the thresholds for diastolic dysfunction were met (EDP, dP/dtfunction . These sFinally, parameters for grading diastolic function in the LV were also impaired in the RV following TAC. However, RV diastolic dysfunction remains largely undefined, both clinically and in basic research, and gold standard indicies of RV diastolic function remain to be determined in a patient population .HF, either clinically or experimentally, is not defined by the presence or absence of pulmonary edema. Indeed, congestion is neither always expected in HF nor always due to pulmonary edema. In fact, pulmonary edema is rare in patients with HF , particuWhile we characterize cardiac function and morphology across multiple time points, we do so in young healthy male mice when the clinical HF population is variably aged and both sexes. Indeed, the necessary next step is to apply this ‘mapping’ approach using aged male and female subjects. Future pre-clinical models might also benefit from an assessment of frequently used clinical variables such as blood biomarkers (i.e., BNP; The goal of HF research is to translate findings to the clinical population to improve survival and quality of life. As too few drugs make the transition from bench to bedside , there iMP, JH, KB, and JS conceptualized the study, designed the experiments, drafted the manuscript, critically revised the manuscript for intellectual content, and gave the final approval for the article. MP, NR, and JH conducted the experiments. All authors analyzed and/or interpreted the experimental results and read and gave permission to the final draft of the manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Restrictive cardiomyopathy (RCM) is the least common among cardiomyopathies. It can be idiopathic, familial, or secondary to systematic disorders. Marked increase in left and/or right ventricular filling pressures causes symptoms and signs of congestive heart failure. Electrocardiographic findings are nonspecific and include atrioventricular conduction and QRS complex abnormalities and supraventricular and ventricular arrhythmias. Echocardiography and cardiac magnetic resonance (CMR) play a major role in diagnosis. Echocardiography reveals normal or hypertrophied ventricles, preserved systolic function, marked biatrial enlargement, and impaired diastolic function, often with restrictive filling pattern. CMR offering a higher spatial resolution than echocardiography can provide detailed information about anatomic structures, perfusion, ventricular function, and tissue characterization. CMR with late gadolinium enhancement (LGE) and novel approaches  can direct the diagnosis to specific subtypes of RCM, depending on the pattern of scar formation. When noninvasive studies have failed, endomyocardial biopsy is required. Differentiation between RCM and constrictive pericarditis (CP), nowadays by echocardiography, is important since both present as heart failure with normal-sized ventricles and preserved ejection fraction but CP can be treated by means of anti-inflammatory and surgical treatment, while the treatment options of RCM are dictated by the underlying condition. Prognosis is generally poor despite optimal medical treatment. According to a recent position statement of the European Society of Cardiology (ESC) working group on myocardial and pericardial diseases, cardiomyopathy is defined as a myocardial disorder in which there is abnormality in the structure and function of the myocytes, in the absence of coronary artery disease, hypertension, valvular disease, and congenital heart disease that could justify this abnormality. In the past, cardiomyopathies were also separated from systematic disorders that could involve the myocardium. ESC classification proposes a shift from diagnosing by exclusion criteria and focusing on the morphology and function of the heart .Restrictive cardiomyopathy (RCM) is the least common of cardiomyopathies. It is characterized by impaired diastolic function with restrictive filling and reduced diastolic volume of either or both ventricles, preserved systolic function, and invariably normal or mildly increased wall thickness . Due to There are many classification criteria for the causes of RCM. According to the ESC Working group in myocardial and pericardial disease RCM can be idiopathic, familial , or secondary to systematic disorders  Table 1Table 1. 3 and S4 gallops). The ECG may reveal sinus rhythm with signs of left or biatrial enlargement or atrial fibrillation. There may be nonspecific ST and T wave abnormalities. QRS voltage may be low in the precordial leads and conductive disturbances may also occur, particularly in infiltrative diseases. Specific ECG findings may occur depending on the underlying cause and aid in the diagnostic work-up.Patients commonly present with dyspnea, fatigue and limited exercise capacity, palpitations, and syncope, while angina may also occur. Others may present with thromboembolic complications. Physical examination may reveal signs of congestive heart failure .A complete evaluation should be performed as restrictive cardiomyopathy may originate from systematic disorders or can in turn affect other organs as heart failure develops. Hematocrit (HCT), serum electrolytes, blood urea nitrogen (BUN), creatinine, 24 hr urine total protein, and liver function should be assessed. Arterial blood gas (ABG) should also be obtained to monitor hypoxia. Serum brain natriuretic peptide (BNP) or N-terminal pro-b-type natriuretic peptide (NT-proBNP) and troponin T are indicative of the heart failure and in many cases predictors of survival –7. SpeciEchocardiography is the first imaging modality for the assessment of patients with dyspnea and/or heart failure. In patients with RCM, it usually discloses nonspecific findings such as normal (not dilated) ventricles with normal or increased wall thickness Figures  althoughOne of the main utilities of echocardiography is the differential diagnosis between constrictive pericarditis (CP) and RCM. Both present as heart failure with normal-sized ventricles and preserved EF, dilated atria, and Doppler findings of increased filling pressure (often restrictive filling pattern). Differential diagnosis is important since CP can be treated by means of anti-inflammatory drugs or surgery while the treatment options of RCM are dictated by the underlying condition. For the main differences between those disease states, the reader can refer to Echocardiography is unable to establish the definite diagnosis of specific RCM subtypes due to its inherent poor tissue characterization and limited assessment of the ventricular apex and the right ventricle. Cardiac Magnetic Resonance (CMR) with a higher spatial resolution and late gadolinium enhancement (LGE) can provide detailed information about anatomic structures, perfusion, ventricular function, and tissue characterization . Late gaAs of this writing, Cardiac CT has no specific role in the work-up of patients with RCM. It can accurately exclude the presence of coronary obstructive artery disease in patients with angina symptom. Its main role is in the differential diagnosis between RCM and CP where it can give invaluable information about the thickness and composition of the pericardium .In contemporary practice, invasive catheterization and coronary angiography are rarely needed for the establishment of diagnosis. In cases where chest pain is the predominant symptom, it can reveal the presence or absence of obstructive coronary artery disease. Left and right heart catheterization can be used when findings of noninvasive tests, including the differential diagnosis between CP and RCM, are nonconclusive .Histological examination can be valuable in setting a definite diagnosis when noninvasive studies have failed, although there are periprocedural risks of endomyocardial biopsy (EMB) . MoreovePrognosis varies among the specific types of RCM but is generally poor with progressive deterioration, particularly in children, despite optimal medical treatment.β-pleated sheets antiparallel to one another, resistant to proteolysis, and they cause oxidative stress, disruption of the myocardium, and myocardial damage Treatment of CS incorporates the guidelines directed medical therapy (GDMT) of heart failure with the addition of corticosteroids to reduce the inflammatory process (except asymptomatic hilar adenopathy where no therapy is required). FDG-PET is suggested in the treatment algorithm for the follow-up , defininHemochromatosis is a group of disorders which leads to excessive accumulation of iron within the cells of liver, pancreas, heart, and several endocrine glands leading to cirrhosis, diabetes, heart failure, skin pigmentation, and so forth. It may be hereditary or secondary. In the former, properly called hemochromatosis , transfe∗) technique has been used to quantify myocardial iron overload [∗ values smaller than 20 msec are predictive of adverse cardiac events [Recently CMR with the use of T2 star  and is an uncommon cause of restrictive cardiomyopathy. HES are either primary, first described by Löffler , or seco eos/mm3 . Indepen eos/mm3 . Primaryolvement , 82.Cardiac infiltration consists of three stages: (a) acute necrotic stage, (b) thrombotic stage, and (c) fibroting stage. The first stage is characterized by inflammation where eosinophilic degranulation releases toxic proteins that induce endocardial necrosis and apoptosis. Rarely, acute necrotizing myocarditis may ensue with high early mortality without appropriate treatment. If left untreated, the first stage evolves into the thrombotic stage due to continuous eosinophilic activation. It consists of thrombus formation over the affected endocardium. Typically there is thrombotic obliteration of left and/or right ventricular apex which may extend to the ventricular outflow tracts, the basal ventricular segments, or even the atria. Thromboembolic complications dominate the clinical picture at this stage. The final stage is due to scarring and irreversible fibrosis of the endocardium  which mECG findings are nonspecific and include sinus tachycardia with conduction disturbances or nonspecific ST-T segment abnormalities. At the first stage, echocardiography may reveal increased LV wall thickness due to interstitial edema, impaired systolic function with abnormal wall kinetics, although most often ventricular systolic function remains preserved. CMR with LGE may additionally reveal endomyocardial involvement, often with patchy distribution . At the The goals of initial therapy are twofold: first to decrease the eosinophil count and attenuate the inflammatory process and second to treat the underlying cause (if any). Corticosteroids are the mainstay of treatment combined with disease specific interventions, for example, antihelminthic therapy for parasitic infections. Anticoagulation should be initiated at the second stage to prevent thromboembolic complications. Once severe EMF has developed, surgical resection with extended endocardial dissection is the treatment of choice but with poor long-term prognosis. Atrioventricular valve replacement should be undertaken at the time of operation if the valves are affected.α-galactosidase A which breaks down neutral glycosphingolipids [α-galactosidase A activity or by GLA gene sequencing, while female carriers have a normal enzyme activity and gene sequencing is needed [Anderson-Fabry disease is a rare X-linked recessive lysosomal storage disorder, caused by mutations of the GLA gene that encodes golipids . This regolipids –88 whilegolipids . Transiegolipids  or prologolipids  PR intergolipids   and enzyme replacement therapy which is effective in myocardial remodeling and improves peak systolic strain and strain rate  but its Diabetic cardiomyopathy (DMCMP) was firstly described as a dilated phenotype with reduced ejection fraction (HFrEF). Recent studies , 97 showThis is the primary restrictive cardiomyopathy, more commonly affecting women, where hemodynamic abnormalities occur without any specific histological changes and in the absence of ischemic, valvular, and congenital heart disease or hypertension. Patients usually present with overt heart failure. Echocardiographic findings are nonspecific as well, with marked dilation of the atria and normal-sized ventricles with preserved systolic function. Doppler demonstrates elevated LV filling pressures  more oftSystemic sclerosis is an autoimmune disorder that practically affects almost any organ system. Myocardial fibrosis results in heart failure symptoms, while fibrosis of the conduction system may lead to ventricular arrhythmias and sudden cardiac death. Physical examination depends on the organs involved with cardiac manifestations mainly caused by right heart failure . Echocardiographic findings are consistent with restrictive physiology.Radiotherapy used against thoracic malignancies  may provoke several cardiovascular disorders such as coronary artery disease, myocardial fibrosis, valvular heart disease, pericardial disease, and ECG conduction abnormalities. Diffuse interstitial fibrosis after relatively low doses of radiation  ultimateDanon disease is an X-linked disorder, due to primary deficiency of lysosome-associated membrane protein 2 (LAMP2). Symptoms occur in adolescence and include heart failure, mental retardation, and skeletal myopathy. Most patients die of heart failure in the third decade of life . LaboratEchocardiography reveals severe hypertrophy of both ventricles, resembling HCM but the electrophysiological abnormalities, particularly ventricular preexcitation, may give a clue for differentiating the two conditions . In DanoIt is an autosomal recessive disorder caused by repeated Guanine-Adenine-Adenine triplets in the frataxin gene on chromosome 9 . ManifesRestrictive cardiomyopathies are a group of diseases with various genetic or acquired etiologies. They are characterized by marked increase in ventricular filling pressures which cause symptoms and signs of congestive heart failure. Electrocardiogram, echocardiography, CMR with LGE, or novel radionuclide imaging can direct the diagnosis to specific subtypes of RCM which is important as treatment and prognosis differ significantly, but endomyocardial biopsy is the definite means of establishing the diagnosis. Genetic counseling and familial screening are necessary in hereditary forms.


However, spatial heterogeneity in T1 measurements has been observed across different segments and slices. Furthermore, T1 values measured with current T1 mapping sequences are influenced by myocardial T2 values. The objective of this study was to 1) assess the spatial heterogeneity of T1 measurements across different segments and slices in healthy subjects and patients, and 2) determine the association of native T1 with myocardial structure and function.Myocardial fibrosis is involved in the pathology of non-ischemic dilated cardiomyopathy (NICM). Recently, the application of native (non-contrast) myocardial T1 mapping was performed using slice-interleaved T1 mapping sequence (STONE) , as shown in Figure 1 , a higher ECV  and a longer myocardial T2 . After multivariable adjustment, a lower global native T1 time was associated with a higher LVEF , higher right ventricular ejection fraction , and lower left atrial volume index .NICM participants 57 ± 15 years) were predominantly male (74%). By design, all had a reduced LV ejection fraction (mean LVEF 34 ± 10%). Figure 5 years w1 is elevated in a homogeneous manner, suggesting a global  abnormality in myocardial tissue composition. This low variability is similar between healthy and NICM patients across different segments. For subjects with NICM, native T1 is associated with biventricular systolic function and left atrial volume, and may represent a non-contrast marker of tissue remodeling in this cohort.In NICM, native myocardial T


Left ventricular (LV) torsion is an important indicator of cardiac function that is limited by high inter-test variability . We hypothesized that this high inter-test variability is partly due to inconsistent breath-hold positions during serial image acquisitions, which could be significantly improved by using a respiratory navigator for cardiovascular magnetic resonance (CMR) based quantification of LV torsion.We assessed respiratory-related variability in measured LV torsion with two distinct experimental protocols. First, 17 volunteers were recruited for CMR with cine displacement encoding with stimulated echoes (DENSE) in which a respiratory navigator was used to measure and then enforce variability in end-expiratory position between all LV basal and apical acquisitions. From these data, we quantified the inter-test variability of torsion in the absence and presence of enforced end-expiratory position variability, which established an upper bound for the expected torsion variability. For the second experiment , 10 pairs of cine DENSE basal and apical images were each acquired from consecutive breath-holds and consecutive navigator-gated scans (with a single acceptance position). Inter-test variability of torsion was compared between the breath-hold and navigator-gated scans to quantify the variability due to natural breath-hold variation. To demonstrate the importance of these variability reductions, we quantified the reduction in sample size required to detect a clinically meaningful change in LV torsion with the use of a respiratory navigator.p < 0.001). From the second experiment, natural respiratory variability from consecutive breath-holds translated to a variability in torsion of 0.24 ± 0.10°/cm, which was significantly higher than the variability from navigator-gated scans . By using a respiratory navigator with DENSE, theoretical sample sizes were reduced from 66 to 16 and 26 to 15 as calculated from the two experiments.The mean torsion was 3.4 ± 0.2°/cm. From the first experiment, enforced variability in end-expiratory position translated to considerable variability in measured torsion (0.56 ± 0.34°/cm), whereas inter-test variability with consistent end-expiratory position was 57% lower  of the inter-test variability of LV torsion can be reduced by using a respiratory navigator to ensure a consistent breath-hold position between image acquisitions. Left ventricular (LV) torsion is an important indicator of cardiac function , 2; howeLV torsion is typically quantified as the gradient of twist along the longitudinal axis of the heart. This gradient is computed using twist derived from two short-axis images  of the LV and the longitudinal distance between the images  Fig. 1)1). End-eWhen post-processing the image data to compute LV torsion, the longitudinal distance between the short-axis images is calculated from either A) assumptions derived from an additional longitudinal image (echocardiography) or B) information specifying the location of the imaging planes in 3D space taken from the Digital Imaging and Communications in Medicine (DICOM) image header (cardiovascular magnetic resonance [CMR]). A confounding factor that is not considered is that the exact end-expiratory position may differ by up to 13 mm between separate breath-holds –10, whicenforced variability in end-expiratory position between acquisitions and 2) allowing for natural variability in end-expiratory position between acquisitions. The former experiment was performed to establish an upper bound on respiratory-related variability in torsion, while the latter mimics a more relevant clinical setting. In both experiments, the effect of using a respiratory navigator to ensure a consistent end-expiratory position on torsion variability was also quantified. The local Institutional Review Board approved the study protocols, and all subjects provided written informed consent.Respiratory-related variability in measured LV torsion was assessed with two distinct experimental protocols: 1) using Imaging was performed on a 3 Tesla Siemens Tim Trio  with a 6-element chest coil and a 24-element spine coil. LV twist was measured at basal and apical short-axis locations in both experiments using 2D spiral cine Displacement Encoding with Stimulated Echoes (DENSE) CMR , 12.2, pixel spacing = 2.8x2.8 mm2, slice thickness = 8 mm, TE/TR = 1.1/17 ms, temporal resolution = 34 ms, variable flip angle = 20°, displacement encoding = 0.06 cyc/mm [The basal and apical short-axis locations were defined as follows: On a four-chamber image, five short-axis slices were planned equidistant across the end-systolic endocardial ventricular long-axis length. The slices were planned such that the outermost slices did not extend beyond the mitral valve plane and endocardial apex, respectively. The second and fourth slices of this stack were defined as the basal and apical short-axis locations. Imaging parameters were: spiral interleaves = 6, interleaves per frame = 2, FOV = 360x360 mm6 cyc/mm , through6 cyc/mm , CSPAMM 6 cyc/mm , view shDENSEanalysis [analysis  was usedanalysis . Post-pranalysis . A semi-analysis .ϕ) divided by the distance (d) between the basal and apical image locations [LV twist was computed over the cardiac cycle relative to the centroid of the endocardial boundary at end-diastole. The distance between the basal and apical image locations was calculated from the DICOM headers. LV torsion was computed as the difference in rotation between the apex and base  were recruited. We first quantified the end-expiratory variability for each subject by acquiring respiratory navigator measurements  during consecutive breath-holds, and 2) during consecutive navigator-gated acquisitions with a single acceptance window location. In each case, the 10 image pairs were used to derive 20 measurements of LV torsion, by combining each basal twist measurement with the two closest apical twist measurements in the temporal sequence. The torsion variability between these protocols was then quantified to compare the differences as a result of consistent (navigator-gated) and inconsistent (breath-hold) end-expiratory positions. Importantly, to monitor the end-expiratory position of the breath-hold acquisitions, the scans were acquired with the respiratory navigator enabled, but with a wide (±50 mm) acceptance window width that never resulted in the exclusion of acquired image data.Statistical analyses were performed using R version 3.2.2 . All continuous variables were expressed as mean ± standard deviation and group means were compared using student’s t-tests. Pearson correlation was used to observe associations between continuous variables.For experiment 1, the inter-test variability of torsion was quantified using 95% inter-test limits of agreement of the two middle navigator acceptance window scans. To test for an overall difference in variability between inconsistent and consistent end-expiratory positions, the LV torsion permutations from the variable end-expiratory positions were compared to the 95% inter-test limits of agreement using a binomial test to evaluate whether values fell within the 95% limits significantly less than 95% of the time. The root mean squared error (RMSE) was then computed to quantify the differences in variability. Specifically, the RMSE for the consistent end-expiratory position was computed by computing the mean squared error (MSE) of the two middle acceptance window scans and taking the square root. The RMSE for the LV torsion permutations was computed by separately computing the MSE of the permutations with respect to each of the two middle acceptance window scans, averaging the MSEs, and taking the square root.p < 0.05.For experiment 2, breath-hold and navigator-gated acquisitions were compared by computing the standard deviations of the 20 respective measurements and performing a Student’s t-test. Variability in torsion was also quantified using 95% inter-test limits of agreement, which were computed using the standard deviation of the difference between consecutive pairs of torsion measurements. For all statistical tests, significance was defined as σ) and the equation:P is the power, f is the value of the factor for different values of α and P (f = 10.5 for α = 0.05 and P = 0.90), and δ is the magnitude of the difference to be detected [To quantify the effects of the differences in torsion measurement variability, we computed theoretical sample sizes required to detect a clinically meaningful change in LV torsion for each experimental condition. Study sample sizes required to detect a 10% relative difference in LV torsion with a power of 90% and a significance level of 0.05 were computed using the standard deviation of the inter-test differences in torsion  and seven patients  were enrolled. One healthy volunteer was excluded due to movement during imaging, so data from the remaining nine healthy volunteers are reported. For experiment 2, 20 healthy volunteers  were enrolled.p = 0.94 and p = 0.70, respectively; Fig. From experiment 1, the intra-subject range and standard deviation of end-expiratory positions were 10.2 ± 4.4 mm and 3.3 ± 1.4 mm, respectively. There was no significant difference in the range or standard deviation of end-expiratory position between healthy and patient groups (p < 0.001). Specifically, the RMSE of LV torsion permutations across end-expiratory positions was 0.56 ± 0.24°/cm (range: 0.2–1.3°/cm), while the RMSE from a consistent end-expiratory position was 57% lower (0.24 ± 0.16°/cm). Moreover, there was a moderate correlation across subjects between the torsion RMSE and the range of end-expiratory positions .DENSE images and displacements from a representative subject show the relative twist differences between the base and apex at end-systole Fig. . Table 1p = 0.02). There was a moderate correlation across subjects between the standard deviation of torsion and the standard deviation of end-expiratory position . By comparison, sample sizes based on measurements with variable end-expiratory positions were up to 313% higher. Additionally, compared to other modalities, using a respiratory navigator with DENSE provided a 80 to 86% reduction in the required sample size compared to CMR tagging [The theoretical sample sizes required to detect a 10% relative difference in peak torsion δ = 0.34°/cm) from each experimental protocol are shown in Table 4°/cm fron = 66 to n = 16 (from enforced variability to consistent) and n = 26 to n = 15 ; 3) the variability of LV torsion due to inconsistent end-expiratory positions had a modest correlation with the variability in end-expiratory positions, such that greater inconsistency in end-expiratory positions was associated with larger errors in measured LV torsion. Regarding inconsistency in end-expiratory positions, within each subject, substantial inconsistency existed with a mean range of 10 ± 4 mm and 14 ± 10 mm in experiment 1 and 2, respectively, which was similar to that reported previously (7 to 13 mm) [This study explored the effects of inconsistent end-expiratory diaphragm positions on the quantification of LV torsion and how enforcing a consistent end-expiratory position with a respiratory navigator can significantly reduce inter-test variability of measured LV torsion. Our primary findings include 1) using a respiratory navigator with DENSE to enforce a consistent end-expiratory position reduced the variability in measured torsion by 22–57%; 2) this decreased variability reduced the required sample sizes to detect a 10% relative difference in torsion from LV torsion is an important indicator of cardiac function because it integrates the three-dimensional deformation of the complex myocardial fiber architecture into a single metric , 2. In mFor LV torsion to be a useful clinical measurement, minimizing the magnitudes and sources of measurement error is important. A previous CMR tagging study reported mean torsion values of 3.4°/cm with inter-study 95% limits of agreement of ±1.6°/cm, representing a large percentage of the mean . Using DFrom experiment 1, by comparing the variability of LV torsion inclusive of enforced inconsistent end-expiratory positions (0.56 ± 0.34°/cm) to the variability without this inconsistency (0.24 ± 0.16°/cm), we determined that using a respiratory navigator to ensure a consistent end-expiratory position reduced the variability in measured LV torsion by 57%. In experiment 2, using a respiratory navigator reduced the variability in measured LV torsion by 22% compared to the variability in LV torsion inclusive of naturally inconsistent end-expiratory positions.variability in measured LV torsion. A previous CMR study examined the bias in LV twist and circumferential-longitudinal (CL) shear angle between different acquisition techniques, including breath-holds and free-breathing [In this study, we examined reathing . In agrereathing , we did n = 16 subjects, which is about 76% lower than the sample size required when using DENSE without a respiratory navigator (n = 66). In experiment 2, we found similar results where using DENSE with natural respiratory variability required a sample size of 26 compared to using DENSE with a respiratory navigator (n = 15). Using a respiratory navigator with DENSE provided a 80 to 86% reduction in the required sample size compared to CMR tagging [To detect a 10% relative difference in peak LV torsion, experiment 1 found that using DENSE with a respiratory navigator required a sample size of only  tagging , CMR fea tagging , and 3D tor n = 1. Using aThese findings have meaningful implications for future CMR-based quantification of LV torsion in the clinical and research settings. First, acquisition of LV torsion data using a respiratory navigator should be employed, where feasible, to minimize variability. This approach is not typical in the majority of published papers reporting torsion and may reduce clinical feasibility of such data acquisition; however, the additional effort appears justified by the considerable reduction in variance. If inconsistency in end-expiratory position is not addressed with the data acquisition, then it is important to incorporate effects of inconsistent end-expiratory position into the assessment of the standard error of measurement for LV torsion, which will substantially increase needed sample sizes for research trials or reduce prognostic value for individual subjects.These results also have important implications for echocardiography. While operators may be able to correct for inconsistency in end-expiratory position by adjusting the position of the probe, it is unlikely that the operator can recreate the exact distance between each short-axis image that was measured from the long-axis image. Because inconsistent end-expiratory positions is a source of measurement variability in measured LV torsion in CMR, the discrepancy in distances may be a source of substantial variability in measured LV torsion in echocardiography.We used spiral cine DENSE to investigate our hypothesis that inconsistent end-expiratory positions accounts for a significant portion of the variability in measured torsion and that inter-test reproducibility could be improved by using a respiratory navigator. We chose to use spiral cine DENSE to investigate our hypothesis since it allows for simple quantification of mechanics, has good spatial resolution, has good reproducibility, and includes a respiratory navigator, which allows control of the end-expiratory position during image acquisition , 31–33. We examined the effects of variable end-expiratory position on LV torsion in a small patient sample. It may be beneficial to examine these results in a larger, more heterogeneous patient sample to determine whether specific diseases affect the results more than others, especially conditions that affect a patient’s ability to repeatedly hold his or her breath reproducibly .Due to the lengthy duration of DENSE breath-holds (~20 s) and their limitations in breath-holding ability, the breath-hold acquisition protocol was not performed in patients. Based on these factors, we expect that patients would demonstrate higher variability in LV torsion with the breath-hold measures compared to the healthy volunteers we studied. Hence, the potential reduction in mean variability when using the respiratory navigator may in fact be higher than the 22% we report from the healthy volunteers in experiment 2. Nevertheless, the reduction in LV torsion variability patients will achieve by using a respiratory navigator will likely fall between the study’s reported values of 22 and 57%.Using a respiratory navigator to enforce a consistent end-expiratory position during image acquisition can reduce the variability in measured LV torsion by 22-57%. Accounting for inconsistent end-expiratory positions results in favorable inter-test variability and reduces required sample sizes by 80 to 86% compared to previous studies. Future efforts to measure LV torsion should use a respiratory navigator or similar form of consistent respiratory compensation.


Sarcoidosis is an idiopathic granulomatous disease that can affect any organ system, including the heart. We examined the predictive relationship of CMR imaging and clinical parameters with major adverse cardiac events (MACE) in patients with sarcoidosis.A consecutive series of 93 study subjects undergoing clinical CMR for evaluation of cardiac sarcoidosis from 2002 to 2012 were identified from the CMR reporting database. All studies were performed using a 1.5T CMR system (Philips Achieva). Anatomic, functional and late gadolinium enhanced (LGE) images were acquired and analyzed according to standard clinical protocols. Clinical data were derived from the medical record. Vital status was confirmed using medical record and the Social Security Administration Death Master File. MACE was defined as mortality, ventricular arrhythmia, or device placement. Relationship to MACE was evaluated using proportional hazards regression.The cohort characteristics are shown in the table. Evidence of extracardiac sarcoidosis was present in 81(87%) and proven by biopsy in 39(42%). MACE occurred in 28(30%); 7(8%) died, 16(17%) had ventricular arrhythmia, and 11 (12%) underwent device placement. Analysis results are shown in the Table, including elements of the Japanese Ministry of Health guidelines for diagnosis of cardiac sarcoidosis revised in 2006 and imaging measurements. CMR measures associated with MACE include left and right atrial size, and left ventricular cavity size, mass, and function. LGE had a borderline association with MACE but was not associated with mortality. Study subjects who received steroid therapy had a reduction in MACE that was borderline significant but with no apparent reduction in mortality.In this cohort of consecutive patients with sarcoidosis referred for CMR, measures of left and right atrial size, and left ventricular size, mass and function were highly predictive of both MACE and mortality. LGE was borderline associated with MACE but not predictive of mortality. Steroid therapy had a trend toward reduction of MACE but no influence on mortality. These data support the role of CMR in the routine evaluation of all patients with suspected cardiac sarcoidosis.


Our laboratory has generated cTnI knockout mouse model to investigate the cellular and molecular function of cTnI and created cTnI mutant disease mouse models to explore the pathophysiology caused by cTnI mutations in the heart. Here, we present our recent studies on physiological function of cTnI in the heart and the pathological consequences caused by the cTnI mutations in the diseased heart using the transgenic mouse models. The mechanisms underlying diastolic dysfunction and heart failure caused by cTnI mutations are explored in cell-based assays and in transgenic animal models. These studies provide us with useful information in searching for therapeutic strategies and target-oriented medication for the treatment of diastolic dysfunction and heart failure.Troponin, a contractile protein of the thin filament of striated muscle, consists of three subunits: troponin C (TnC), troponin T (TnT), and troponin I (TnI). Cardiac troponin I (cTnI) plays a critical role in regulation of cardiac function. The physiological effect of cTnI, as an inhibitory subunit of troponin complex, is to prevent the interaction between myosin heavy chain heads and actins, i.e. the cross-bridge formation, and to ensure a proper relaxation of cardiac myofilaments. In pathological conditions, the deficiency of cTnI or mutations in cTnI especially in the C-terminus of cTnI is associated with diastolic dysfunction caused by myofibril hypersensitivity to Ca Heart failure is a leading cause of mortality in the United States. Up to 40% of heart failure patients have impaired relaxation, known as diastolic dysfunction and diastolic heart failure with normal systolic performance. Diastolic heart failure is an important clinical syndrome and both hypertrophic cardiomyopathy (HCM) and restrictive cardiomyopathy (RCM) share the same feature of diastolic dysfunction. It is known that single cardiac myofibril gene mutations are associated with cardiomyopathies leading to diastolic heart failures. However, the mechanisms underlying the impaired relaxation in myocardial cells and diastolic dysfunction developed in the heart are unknown. There is a critical need to understand the mechanisms that cause diastolic dysfunction and heart failure and to develop target-based intervention and medications to correct the overt condition and to treat the patients. For the moment, in the absence of such agents and intervention, treatment of diastolic dysfunction is difficult and often ineffective . Our labHomologous recombination in embryonic stem (ES) cells was used to delete the entire cTnI gene from the mouse genome. In cTnI gene knockout mice (cTnI-KO), all homozygous mutants die on days 17 or 18 after birth, whereas the heterozygous mutants have a similar life span as that of the wild type mice . By cros193His) had 20-40% mortality rates and developed RCM phenotype similar to that observed in RCM patients [178Glu and cTnI205His mice were lethal and died a couple of days after birth. By crossing the cTnI193His mice with heterozygous cTnI-KO mice, we generated various transgenic mouse lines expressing different levels of cTnI R193H in myocardial cells [Our laboratory has created transgenic (TG) mice containing the RCM cTnI R193H and K178E mutations reported by Mogensen  and tran193His in RCM TG mice. The mortality rate was monitored and recorded in the different transgenic lines and their cardiac function was measured to determine any functional change related to the expression level of cTnI193His. Cardiac function assessments were performed by using a Vevo 770 High-resolution In Vivo Imaging System from VisualSonics . 10 mice  per line including wild type were analyzed. The animals were first anesthetized with isoflurane at a concentration of 5% and then maintained at 1.1% isoflurane by a facemask during the procedure. Mouse body temperature and ECG measurement were taken during the whole process. The ventricular chamber sizes during systole and diastole, and the septal and ventricular wall thickness were measured through M mode imaging. B mode imaging 4-chamber view was taken to measure atrial size. The mitral inflow was evaluated with the Pulse-Wave Doppler and the following parameters measured: early ventricular filling (E wave); late ventricular filling caused by atrial contraction (A wave); ejection time (ET); isovolumetric relaxation time (IVRT); deceleration time (DT); isovolumetric contraction time (IVCT). Doppler Tissue Imaging (DTI) analyses were also performed to determine the mitral annulus velocity in the hearts. The E/A, E’/A’ and E/E’ ratios were calculated as reported previously [We have analyzed the dose-dependent negative effect of cTnIeviously -10.Myocardial cells were isolated freshly from experimental mouse hearts. The following cell-based assays were performed on these myocardial cells.The resting sarcomere length in both WT and RCM myocardial cells was measured using the IonOptix system  as reported previously , 10. Car2, 1 MgCl2, 10 Glucose, 10 HEPES, at pH 7.4 with 1% BSA and 0.02% pluronic F-127 (Molecular Probes). After 30 minutes of de-esterification of the fura-2 AM, the cells were bathed in Tyrode solution. For measurement, the fura-2 loaded cardiomyocytes were excited by UV light  and the fura-2 emission wavelength (510 nm) was recorded with a photomultiplier tube. The kinetics of Ca2+ transients were analyzed in conjunction with myocyte mechanical measurements.The calcium transients on the cardiomyocytes isolated from the various RCM transgenic lines and the WT mice were measured as reported previously , 10. FreTwo main TnI genes are expressed in the mammalian heart under the control of a developmentally regulated program. Fetal TnI, which is identical to slow skeletal TnI (ssTnI), is expressed first and predominates throughout embryonic and fetal development. Around embryonic day 10, cTnI begins to be expressed. Soon after birth, cTnI accounts for roughly half of the total thin-filament TnI content, and then cTnI predominates throughout adulthood in most animals, including humans. In the cTnI-KO mice, ssTnI was found to compensate for the absence of cTnI, but only temporarily, as ssTnI was eventually down-regulated in the cTnI-KO mouse heart.in vivo.Since ssTnI could be down-regulated as usual during the TnI isoform switch, a mammalian model with a myocardial TnI deficiency was created in homozygous mutants about two weeks after birth and all these homozygous mutant mice died on day 18 after birth when the TnI content was declined below 40% of the total TnI amount in the heart . The his193His) expressing human RCM mutation cTnI R192H (cTnI R193H in mouse sequence) in the heart. The cTnI193His mice do not present with significant hypertrophy or ventricular dilation. They have a phenotype similar to that in human RCM patients carrying the same mutation characterized morphologically by enlarged atria and restricted ventricles and functionally by diastolic dysfunction and diastolic heart failure [Our laboratory has been among the first to begin to define the effect of the RCM cTnI mutation on the development of diastolic dysfunction. We have created transgenic mice cTnI19His expre193His mice, indicating an increase of myofibril sensitivity to Ca2+ [2+ transient measurements and biochemical assays indicated that cTnI mutation caused myofibril Ca2+ hypersensitivity was a key factor resulting in a delayed calcium drop-off from the myofilaments and a delayed relaxation time [The results from the cell-based assays demonstrated that impaired relaxation was a key that causes restricted ventricle in the RCM cTnI R193H mice [ to Ca2+ . The dation time , 12.2+ hypersensitivity in myocardial cells caused by RCM cTnI mutations is a key that results in a delayed Ca2+ drop-off rate and an impaired relaxation. To confirm this, we have carried out experimental animal assays to desensitize the hypersensitivity in the RCM myocardial cells.Based on our studies, we have demonstrated that Ca2+ sensitivity was decreased in the presence of cTnI-ND and diastolic function improved. The therapeutic effect of this cTnI desensitizing molecule was investigated in our RCM cTnI193His mice presenting damaged diastolic function. Double transgenic mice (Double-TG) were created that express both cTnI-ND and the cTnI R193H in the heart. The results indicated that Ca2+ sensitivity was restored in the animals accompanied with improved diastolic function and increased life span [Proteolysis of the N terminal of cTnI (cTnI-ND) occurs as a functional adaptation in simulated microgravity and also under physiological and stress conditions . The phoife span . Such fi2+ desensitizers that can be used to alter myofibril sensitivity for Ca2+ and myofilament sliding kinetics. A great concern about biological agents is their non-toxicity and their good bioavailability but there are few Ca2+ desensitizers possessing such qualities. The catechin, (-)-epigallocatechin-3- gallate (EGCg) has been newly found to possess Ca2+ desensitizing abilities via its interaction with cTnC [2+ by forming a ternary complex with the C-terminal domain of troponin C and the anchoring region of cTnI [2+ is reduced as a result which facilitates cardiac relaxation.There is a great need to develop or find small molecules and chemical Caith cTnC , 15. Thi193His mice as shown by a restored left ventricle end diastolic dimension (LVEDD) in M mode imaging , troponin T (TnT) and TnI. TnI is the inhibitory subunit which can bind to actin-tropomyosin and prevent muscle contraction by inhibition of actintropomyosin- activated myosin (actomyosin) ATPase activity. It has an important function in the regulation of striated muscle contraction. At basal levels of calcium, TnI inhibits actin-myosin crossbridges. In systole, as calcium binds to the regulatory site of TnC, the inhibitory action of TnI is released thereby activating muscle contraction. Cardiac contractionrelaxation is regulated mainly by intracellular calcium concentration and the proteins that are involved in the regulation of calcium cycling in myocardial cells, such as Ca2+-independent force) is high in these myofibrils due to a tighter interaction between myosin and actin in the absence of TnI, which results in an impaired relaxation and diastolic heart failure even death. The fetal isoform of TnI, ssTnI, can compensate for the absence of cTnI by prolonging its expression time after birth. However, this compensation is temporary and the ssTnI gene turns off 18 days after birth in cTnI-KO mice. It is clinically important to understand the TnI isoform switching and the epigenetic regulation of TnI gene expression since the TnI content is reported to be decreased in aging hearts. If we understand clearly the regulation of TnI gene (cTnI or ssTnI), we can induce the expression of the TnI gene in case the heart needs more TnI.Our studies have demonstrated that troponin is critical in the maintenance of a normal cardiac function and in the regulation of cardiac muscle movement. In the case of TnI deficiency or decrease, rest tension (Ca2+ and reversing the phenotype of RCM.From the studies using the transgenic RCM mice, we have demonstrated that hypersensitivity in RCM myocardial cells is a key factor that causes a delayed calcium drop-off rate from myofibrils and an impaired relaxation, which in turn results in diastolic dysfunction and heart failure. Our experimental therapeutic experiments have confirmed that desensitization is effective in correcting hypersensitivity of myofibril to Ca2+ is important as well. It is clinically important to propose this novel concept since almost half of the heart failure patients have diastolic dysfunction and no effective medication is available so far for the diastolic dysfunction and heart failure. Calcium desensitization may be useful in the treatment of diastolic dysfunction and heart failure.Our studies indicate that to have a normal cardiac contraction and relaxation, calcium concentration is critical. In addition, myofibril sensitivity to Ca