Such unique flow-specific measures of mechanical dyssynchrony may serve as an additional tool for considering the risks imposed by conduction abnormalities in heart failure patients and prove to be useful in predicting response to CRT.Left bundle branch block (LBBB) causes left ventricular (LV) dyssynchrony which is often associated with heart failure. A significant proportion of heart failure patients do not demonstrate clinical improvement despite cardiac resynchronization therapy (CRT). How LBBB-related effects on LV diastolic function may contribute to those therapeutic failures has not been clarified. We hypothesized that LV hemodynamic forces calculated from 4D flow MRI could serve as a marker of diastolic mechanical dyssynchrony in LBBB hearts. MRI data were acquired in heart failure patients with LBBB or matched patients without LBBB. LV pressure gradients were calculated from the Navier-Stokes equations. Integration of the pressure gradients over the LV volume rendered the hemodynamic forces. The findings demonstrate that the LV filling forces are more orthogonal to the main LV flow direction in heart failure patients with LBBB compared to those without LBBB during early but not late diastole. The greater the conduction abnormality the greater the discordance of LV filling force with the predominant LV flow direction (r Around 25 percent of patients with congestive heart failure may have Left Bundle Branch Block (LBBB)2. LBBB causes dyssynchronous LV contraction and relaxation, and contributes to impaired left ventricular (LV) performance. The majority of studies have investigated the impact of LBBB on systolic LV function. Dyssynchronous and delayed relaxation may have important impact on LV filling properties and diastolic function as well.Heart failure is a common clinical problem and adverse cardiac remodeling is a key component in the deterioration of cardiac function, in the downward spiral leading towards heart failure. Increased myocardial wall stress during diastole contributes to the development and progression of adverse cardiac remodeling6. Previous studies have shown that the distributions of different flow components comprising the end diastolic volume (EDV) of LV may be markers of cardiac function11. Another approach to assess intracardiac blood flow has been calculation of the kinetic energy of the blood8. In this approach, the directionality of the blood flow is lost. Furthermore, from the velocity field and by the use of governing equations, pressure gradients and relative pressure fields can be calculated15. By integration of the pressure gradients throughout the LV blood pool, a vector is obtained describing the total force between the LV blood and the surrounding myocardial walls: the LV hemodynamic force.Time-resolved three-directional three-dimensional velocity (4D flow) data, acquired by magnetic resonance imaging (MRI), provides important information regarding intracardiac blood flow and cardiac functionThe hemodynamic force concept is based upon Newton’s third law (the action-reaction law). According to this law, the accelerating and decelerating blood exerts a force on the surrounding myocardial walls, while the myocardial walls exert a force on the blood. These forces are equal in size, but opposite in direction. As blood flows from the left atrium into the LV it will augment the pressure in the LV, resulting in deceleration of the blood. The blood will have higher velocity in the basal part of the LV and decelerate as it progresses towards the apex. This means that the pressure gradient will be positive along the flow direction , hence, the hemodynamic force, the force the blood exerts on the myocardial wall, will be directed towards the apex. During systole the velocity is increased from apex towards the LVOT, the pressure gradient will be negative from apex to LVOT, i.e. the pressure will decrease in the flow direction and the hemodynamic force will be directed in the opposite direction. Note that the myocardium will exert a force on the blood that is equal in size, but opposite in direction.16, but was only recently computed from 2D LV flow fields by Pedrizetti et al., using echocardiographic particle image velocimetry (echo-PIV)18. Using this technique, the directional distribution of hemodynamic forces in the LV of heart failure patients with cardiac resynchronization therapy (CRT) has been investigated19. In this study patients with dilated cardiomyopathy that had undergone CRT implantation were examined by echocardiography before and after a temporary deactivation of the CRT. The results showed that the orientation of flow momentum changed from along the LV long axis direction to along the short axis direction during deactivation.The concept of LV hemodynamic force has been known for decades20. In a recent study, we hypothesized that in a healthy heart the hemodynamic force should be directed concordant with the main flow direction, apex-to-base, and that changes in this pattern would reflect abnormal LV function20. Therefore, we examined the relative distribution of the hemodynamic force along the long (apex-to-base) axis and that acting in the short  axis during diastolic filling. In a heterogeneous group of dilated cardiomyopathy patients we found that the ratio of forces acting in the long- and short-directions was different from normal, especially during early filling, with a relative increase in the hemodynamic forces acting orthogonal to the main flow axis20.We extended this approach for 3D flow field obtained from 4D flow MRIIn this work we sought to investigate the impact of LBBB-related dyssynchronous LV relaxation on global LV diastolic hemodynamics and function. We hypothesized that in heart failure patients with LBBB, the LV hemodynamic filling forces would be more discordant with the axis of the early inflow, when disordered repolarization would have its greatest impact on filling, compared to matched patients without LBBB, and could therefore serve as a marker of diastolic mechanical dyssynchrony.MRI data were successfully acquired in heart failure patients with LBBB and matched patients without LBBB (from hereby referred to as the non-LBBB group). As expected, the QRS duration was significantly longer in LBBB versus non-LBBB patients (154 (64) ms vs 106 (24) ms, P < 0.0001). There were no significant differences between the groups with respect to demographic and clinical parameters, such as age, body size, heart rate, blood pressure, LVEDV-index, and LV ejection fraction  was defined as the ratio between the maximum force along the anteroseptal-to-inferolateral axis in the SAx-view and the maximum force along the apex-to-base axis in the LAx three-chamber view. This ratio, reflecting the deviation of the LV hemodynamic forces from the main LV flow direction, was significantly larger in the LBBB group compared to the non-LBBB for the complete diastolic phase . During early diastolic filling, the SAx/LAx-ratio was significantly larger in the LBBB group compared to the non-LBBB  , showed a trend to be larger at early filling  but showed no inter-group difference at late filling .In order the further evaluate the time profile of the hemodynamic forces, the root mean square (rms) of the force-ratio was computed over all diastolic phases. The SAx/LAx-ratio2 = 0.4857, P = 0.003), while there was no correlation between these two parameters during late diastolic filling , using linear regression analysis , whereas no correlation was observed during late filling .During early diastolic filling there was a moderate to strong correlation between the SAx/LAx-ratio and QRS duration  compared to the matched patients (non-LBBB), while no intergroup difference was observed during late diastolic filling. The ratio computed with root mean square values for the force components in the LAx and SAx showed the same trend during diastole as the ratio of max values. Moreover, we found that the SAx/LAx-ratio and QRS duration correlated during early diastole but not during late diastole.20, the LV hemodynamic forces in heart failure patients in this study also showed a peak directed towards the atrium at onset early and late filling, due to the acceleration of the blood, and towards the apex following early and late filling, due to the deceleration of the blood in the apical region. In the same recent study, a relatively homogenous pattern of hemodynamic filling forces was demonstrated in normal LVs, where the forces were directed concordant with the main flow directions, compared to a considerably more heterogeneous pattern in myopathic LVs, where the forces were to a greater extent orthogonal to the main flow direction20. Arvidsson et al.21 showed that also elite athletes’ LV forces concordant with the main flow direction dominated throughout the cardiac cycle and there were no differences between athletes and healthy volunteers. In addition, two case patients with ventricular dyssynchrony were examined and found to have different force patterns with the LV forces orthogonal to the main flow direction equal to the forces along the main flow direction. In the present study, the intriguing findings from the SAx/LAx-ratios propose that the forces are orthogonal to the main flow direction to a greater extent in the patient group with LBBB compared to the patient group without LBBB during the early diastolic filling phase.As recently observed in normal and myopathic LVset al.19 similar findings were shown in a patient group with CRT where the orientation of blood flow momentum was altered and became more orthogonal to the main LV flow direction when the CRT was deactivated. Although the aim of CRT is to resynchronize intra- and inter-ventricular motion patterns, however, active pacing does not achieve normal electrical activation through the conduction system. Furthermore, deactivation of CRT for a few minutes probably does not completely reflect the underlying ventricular dyssynchrony patterns. Therefore, the findings of this ultrasound study cannot be directly compared to the findings of the present study.Hence, the current heart failure patients with LBBB demonstrated altered LV blood flow dynamics due to changes in the electrical activation of the ventricular myocardium. In an interesting echo-PIV study by Pedrizzetti 24, and it is reasonable to believe that LBBB related alterations in the transit of blood through the chamber may contribute to the difference in force direction between the groups.In the current study, there was no difference in the sphericity index between the two patient groups, implying that the increased SAx/LAx-ratio in the LBBB group is not a result of the altered geometry of the failing ventricles. Altered LV intracavitary flow patterns have previous been demonstrated in enlarged and dysfunctional ventricles25. This delay can lead to a transeptal pressure gradient that allows the interventricular septum to bulge into the LV cavity during early diastole26. Combined with the delayed outward motion of the opposing LV lateral wall, this distortion could influence flow patterns and contribute to the relative increase of the maximal force in SAx plane during early filling.The present study puts emphasis on a mechanism that may be reflected by the SAx/LAx-ratio. In LBBB patients with dyssynchronous LV electrical and mechanical function, RV diastolic filling precedes LV diastolic filling due to the delayed LV relaxationInterestingly, the moderate to strong relationship between the QRS duration and the SAx/LAx-ratio suggests that the greater the conduction abnormality the larger the relative increase in maximal force in the SAx plane.The absence of intergroup difference in SAx/LAx-ratios at late diastole could be explained by that phase’s distinct filling mechanisms that incorporate atrial contract and annular recoil. Hence, late filling is less affected by dyssynchronous LV myocardial relaxation and motion.1. Thus, a LBBB related increase in SAx/LAx-ratio, with relatively higher global force that is discordant with the predominant LV flow direction, could contribute to the development and progression of pathological cardiac remodeling. Interestingly, Pedrizzetti and colleagues showed in their work that the deviation of blood flow momentum from the predominant LV flow direction during deactivation of CRT, correlated with the degree of reversed LV adverse remodeling (reduction in LV volumes) following CRT implantation19.The current findings propose new blood flow based aspects of mechanical dyssynchrony that may prove to contribute to the development and progression of pathological cardiac remodeling. Altered direction and temporal progression of hemodynamic filling forces may alter the pattern of global myocardial wall stress during diastole, which in turn could have impact on the remodeling process27. This is an essential clinical issue, since the number of potential patients is enormous, and the cost per device is high. Specific characteristics of 4D LV hemodynamic filling forces might prove useful in predicting response to CRT and also in future optimization of CRT settings.Potential areas of future application and clinical utility include cardiac resynchronization therapy (CRT). Despite the documented benefits of CRT in many patients, a significant proportion of patients undergoing this therapy do not demonstrate improvementIt is reasonable to expect that LV hemodynamic forces would also be sensitive to conditions associated with altered LV inflow direction, such as with mitral valve dysfunction or prosthetic replacement, or in the setting of significant regional wall motion abnormalities due to myocardial infarction. The impact of these conditions on hemodynamic forces will be pursued in future works.rms) showed the same trend throughout diastole as the force-ratio with the max values (SAx/LAx-ratio): this finding suggests that both values are valid.The SAx/LAx-ratio was computed using the maximum values in SAx and LAx planes, which potentially may be sensitive to noise and artifacts. In order to provide a temporally global measurement less sensitive to noise, the root mean square (rms) of the SAx/LAx-ratio was computed over all diastolic phases, including E-wave as well as A-wave. The rms of the force ratio in the LAx and SAx  and the temporal resolution of the data in this study.In the computation of the hemodynamic forces, the viscous terms in Navier-Stokes equations might be underestimated. They are merely important when assessing parameters in the shear layer close to the walls, however, and therefore should be a minor determinant of the forces examined in the present study. Noise and other artifacts are known to affect the spatial gradients in the Navier-Stokes equations. The effect on the hemodynamic forces is expected to be small, however, as these are derived by integrating the pressure gradients over the entire LV volume.The temporal resolution of the velocity data was 52.8 ms. While better temporal resolution would be preferable, particularly in patients with higher heart rates, this level represents an acceptable tradeoff between acquisition time and temporal resolution. Further, one of the matching parameters between the patient groups is heart rate, so any effects caused by temporal resolution should be present in both groups and not impact the comparisons.Analysis of LV hemodynamic forces is a new and comprehensive approach to visualize and quantify the 4D LV intracavitary blood volume. LV filling forces are orthogonal to the main flow direction to a greater extent in patients with LBBB compared to patients without LBBB during early but not during late diastole. The greater the conduction abnormality the greater the discordance of LV filling force with the predominant LV flow direction. Such unique flow-specific measures of mechanical dyssynchrony may serve as an additional tool for considering the risks imposed by conduction abnormalities in heart failure patients and prove to be useful in predicting response to CRT.Eighteen heart failure patients with ischemic cardiomyopathy (ICMP) or idiopathic dilated cardiomyopathy (IDCMP) were divided into two different groups; 1) patients with LBBB, and 2) patients matched according to gender, age, heart rate, and parameters of LV characteristics without LBBB. Demographic and clinical data for the subjects are presented in Table Inclusion criteria for 1) ICMP patients: diagnosed with ischemic heart disease based on myocardial perfusion scintigraphy tests and/or MRI evidence of myocardial infarction using late gadolinium enhancement; at least mild to moderate systolic LV dysfunction (ejection fraction <45%); 2) IDCMP patients: absence of other (secondary) etiology of DCMP; at least mild to moderate systolic LV dysfunction (ejection fraction <45%); at least mild LV dilatation; 3) LBBB patients: QRS duration >120 ms and typical LBBB pattern on the QRS complex and T wave. Exclusion criteria for all patients were contraindication for MRI examination, significantly irregular cardiac rhythm, heart rate <40 or >100 bpm, more than mild valvular disorder or discrepancy of >15% in the MRI-based estimates of LV inflow and outflow.The patients were enrolled from outpatients at the Department of Cardiology, Linköping University Hospital.All subjects gave written informed consent prior to participation in the study. The study was performed in accordance with the Helsinki declaration and the Regional Ethical Review Board in Linköping. The Regional Ethical Review Board in Linköping also approved the study protocols.All subjects underwent a cardiac MRI examination using a clinical 3T MRI scanner .During the MRI examination, morphological two-, three- and four-chamber long-axis (LAx) images and a stack of short axis (SAx) images were acquired. Time-resolved three-directional velocity (4D flow) data were acquired in a volume encompassing the heart, by the use of a turbo field echo sequence with interleaved bipolar flow encoding gradients. The data were acquired during free-breathing using retrospective navigator gating. The field of view was set in a sagittal position and the number of slices in the slab was adjusted to encompass the heart of each study subject. General acquisition parameters were: spatial resolution, 2.8 mm isotropic; flip angle, 10° ; repetition time, 4.4 ms, echo time, 2.6 ms; velocity encoding, 120 cm/s. A k-space segmentation factor of 3 was applied and parallel imaging with sensitivity encoding (SENSE) with a speed-up factor of 3 was applied and elliptical k-space acquisition was used. These settings gave a temporal resolution of 52.8 ms. The patients were scanned in supine position. Mean total scan duration for the 4D flow acquisition was 16.7 ± 6.9 minutes. All patients (with the exception of five) were given a gadolinium contrast agent  prior to the data acquisition for a late gadolinium enhancement study.th order polynomial fitted to the static tissue in the thorax28 and for phase wraps by the use of a temporal algorithm29.After data acquisition the 4D flow data were reconstructed into 40 time frames on the scanner and exported to an offline station for post processing and analysis. The data was post processed by the use of in-house developed software written in Matlab . The 4D flow data were corrected for background errors by the use of a 4v [m/s] is the velocity, ρ the density (1060 [kg/m3]) and μ the viscosity (0.004 [Ns/m2]) of blood. By integrating the pressure gradients, The LV was segmented at all time frames from SAx stack, with aid from the LAx images in order to determine the most basal slice, by the use of semi-automatic segmentation software . The segmentation was resampled to the same number of time frames as the 4D flow data. The segmentation was manually corrected for possible mismatches due to patient motion assisted by superimposition of the segmentation on the magnitude data of the 4D flow MRI in the SAx orientation. The corrected segmentation was then used to create a binary mask containing the LV lumen. The binary mask was used as boundary conditions to calculate the spatial and temporal gradients in the Navier-Stokes equation : 1060 kg/m) and μ tSpeed data were extracted from two points set in the 4D flow data, at the atrioventricular plane near the mitral valve orifice and near the aortic valve orifice, and plotted over time  and late (A-wave) filling phases separately. The maximum forces in the SAx view and the LAx view were not necessarily extracted at the same time frame, e.g. the E-wave SAx/LAx-ratio was calculated by finding the maximum forces in the LAx and SAx-directions, each at any time during the early diastolic phase.In order to assess the heterogeneity of the force directions the “SAx/LAx-ratio” was calculated Fig. . This rarms) was the calculated over all diastolic phases.In order to provide a temporally inclusive measurement, the rms of the SAx/Lax ratio . An experienced investigator assessed the presence of left sided regurgitant or stenotic valvular disease for exclusion criteria purposes, and LV myocardial hypokinesia or akinesia in patients with ICMP, according to standard recommendations31.The subjects also underwent standard electrocardiographic (ECG) and echocardiographic examinations. The electrocardiographic examination was performed by experienced nurses at the Department of Cardiology, Linkoping University Hospital, using a GE MAC 5500 HD. For inclusion criteria purposes, an experienced investigator assessed the presence of LBBB according to standard definitions: QRS duration > 120 ms and typical LBBB changes to the QRS complex and T waveSyngo Velocity Vector Imaging software version 2.00. The mechanical activation was defined as the mean time delay from the onset of the QRS complex to peak tissue velocity in both longitudinal and radial directions.Measurements of mechanical synchrony were performed in each patient as the time delay between the mechanical activation of the LV septal and lateral wall in a four-chamber echocardiographic view using Siemens The Lilliefors method was used to test the data for normal distribution. Inter-group comparisons were analyzed using t-tests for normally distributed data and Wilcoxon Rank Sum tests for non-normally distributed data (QRS-time). All data are presented as mean ± standard deviation or median (range). Linear regression was used to analyze the relation between SAx/LAx-ratio and QRS duration for E-wave and A-wave, and between SAx/LAx-ratio and septal-lateral delay for E-wave and A-wave. A P-value < 0.05 was considered significant. In one of the LBBB patients the E-wave could not be defined; that patient was excluded from analysis of early versus late diastolic phases.The underlying magnetic resonance imaging, echocardiographic and electrocardiographic data sets are available at the Linköping University Hospital for researchers who meet the criteria for access to confidential data. The computed hemodynamic forces are available from the author upon request.Supplementary Informationpdf


Multiple sclerosis (MS), neurologic disease affecting young population, may cause cardiovascular dysfunction, due to autonomous nervous dysfunction, physical invalidity, increased oxidative stress, and systemic inflammatory status. However, cardiovascular function is rarely evaluated in these patients. We assessed left and right ventricular (LV and RV) function by 2D, 3D, tissue Doppler, and speckle tracking echocardiography, and vascular function by remodeling, stiffness, and endothelial dysfunction parameters in patients with MS, compared to control subjects. 103 subjects  were studied: 67 patients with MS and 36 control subjects. Patients with MS had decreased LV systolic function, confirmed by lower 2D and 3D ejection fraction, mitral annular plane systolic excursion, longitudinal myocardial systolic velocities, and 2D and 3D global longitudinal strain. The RV function was also decreased, as demonstrated by lower fractional area change, tricuspid annular plane systolic excursion, longitudinal systolic velocities, and longitudinal strain. Additionally, LV diastolic and left atrial (LA)  function were decreased compared to controls. The parameters of arterial and endothelial function were similar between groups. Patients with MS have impaired biventricular function by comparison with normal subjects, with reduced LA function, but normal arterial and endothelial function. The noninvasive echocardiographic techniques might help to determine patients with MS at risk of developing cardiovascular dysfunction. MS is the main cause of non-traumatic neurological invalidity in young and middle-aged populations, affecting women two times more frequently than men2.Multiple sclerosis (MS) is a chronic neurological condition, characterized by recurrent episodes of inflammation and demyelinisation of the central nervous system, that determine axonal degeneration and lead to irreversible progressive invalidity3. Patients with MS have a higher mortality rate compared to the general population, and this might be related to an higher incidence of CV disease5. However, cardiovascular function assessment is rarely performed in these patients. Most studies focus on the cardiotoxicity of mitoxantrone, which is nowadays a second line treatment7. Additionally, the majority of these studies assess conventional 2D-echocardiography and tissue Doppler parameters, however, the new techniques, such as speckle tracking echocardiography or real-time 3D-echocardiography, although simple, rapid, and effective in providing early diagnosis of myocardial dysfunction are not used9.The main mechanisms of impaired cardiovascular (CV) function in patients with MS are the cardiomyocite structure alteration, the CV autonomous nervous system dysfunction, physical invalidity, oxidative stress, endothelial dysfunction, and the presence of associated cardiovascular risk factorsThere is little knowledge about the cardiovascular function in MS, and subsequent research is required to improve the understanding of these mechanisms and to develop management algorithms capable to detect and prevent CV adverse events in this population. Therefore, our objective was to extensively assess cardiac and arterial function in patients with MS, compared to control subjects, in order to provide a pilot model for the early detection of CV dysfunction in these group of young patients.We prospectively enrolled 103 subjects , divided in two groups: the MS group with 67 subjects with confirmed MS, and the control group with 36 control subjects. Within the MS group, 35 patients were already treated for more than 6 months with interferon or glatiramer acetate, while 32 patients were newly diagnosed and free of immunomodulatory treatment. Mean duration of MS was 5.2 ± 5.0 years. The two study groups had similar mean age and gender distribution, with an equal incidence of CV risk factors, such as arterial hypertension, dyslipidemia, smoking, and obesity , lower 3D LVEF, lower mitral annular plane systolic excursion (MAPSE), lower “online” longitudinal myocardial systolic velocity (S’), lower global longitudinal strain (LS), and lower 3D LS Table . MeanwhiPatients with MS had impaired LV diastolic function, compared to control subjects, as showed by lower early (E) and late (A) diastolic velocities, lower flow propagation velocities (FPV), and longer isovolumetric relaxation time (IVRT). Meanwhile, in patients with MS, early “online” longitudinal myocardial diastolic velocity (E’) was lower than in control subjects, although the E/E’ ratio was similar between groups. In patients with MS, the untwist rate (UTR) was reduced compared to control subjects, as well as the left atrial systolic  longitudinal strain (LA SLS) Table .Table 3LArterial remodeling, assessed by intima media thickness (IMT), was similar between the groups. Arterial stiffness, assessed by Peterson elastic module Ep, β index, augmentation index (Aix), arterial compliance, and pulse wave velocity carotid-femoral (PWV CF), and endothelial function, assessed by flow mediated dilation (FMD), were also similar between groups Table .Table 4AThe troponin I value, as a marker of myocardial ischemia, was similar between the two groups: 0.0007 ± 0.001 ng/ml in the MS group and 0.0012 ± 0.002 ng/dl in the control group. The N-terminal pro B-type natriuretic peptide (NT-pro BNP), as a marker of heart failure, was also similar between groups: 35 ± 26 pg/ml in the MS group and 37 ± 32 pg/ml in the control group.1 = 32 patients) and treated MS patients (MS2 = 35 patients). There were no significant differences between the two subgroups for any of the echocardiographic parameters, but each of them was different from the control subjects  age between 18 and 65 years; (2) patients with confirmed MS diagnosis, both newly diagnosed or already under immunomodulatory treatment; and (3) informed consent signed. Exclusion criteria were: (1) MS treated with mitoxantrone; (2) patients with known cardiovascular disease; (3) presence of other neurological conditions; (4) any renal, pulmonary, hepatic or hematological disease; (5) diabetes mellitus; (6) any degree of arterial hypertension; (7) pregnancy; (8) difficult acoustic window. The study protocol was approved by the Local Ethic Committee of the University Emergency Hospital Bucharest , and registered on clinicaltrials.org under the identifier NCT03001284. All subjects gave their informed consent and the protocol conforms to the ethical guidelines of the 1975 Declaration of Helsinki, as reflected in a priori approval by our institution’s human research committee. Blood pressure, height, and weight were measured before the echocardiographic examination. Body mass index and body surface area were calculated by Du Bois formula. Following biomarkers were measured: troponin I as a marker of myocardial ischemia and NT-pro BNP as a marker of heart failure. In patients with MS, the invalidity level was calculated using the EDSS score25.We prospectively enrolled patients with confirmed MS, diagnosed according to the revised McDonald’s criteriaAll subjects underwent comprehensive echocardiographic examination using a commercially available ultrasound machine , equipped with a M4S probe and a 3D probe. Standard images were obtained from parasternal long- and short-axis views, and from apical views. Special acquisitions were performed for tissue Doppler, speckle tracking, and 3D-echocardiography. Data were analyzed offline, using a dedicated software package . Electrocardiogram was recorded simultaneously.Conventional echocardiography consisted of M-mode, 2D, and Doppler blood flow measurements, performed according to the current guidelines26. M-mode was used to measure systolic and diastolic thickness of the posterior and septal walls, and left ventricular, systolic and diastolic diameters. We calculated LV volumes and ejection fraction by Simpson’s method, and LV mass and LV mass indexed to body surface area estimated by LV cavity dimension and wall thickness at end-diastole. Mitral annular plane systolic excursion (MAPSE) was calculated from the mean of the lateral and medial annular excursions. Diastolic function was assessed by PW Doppler of the transmitral flow, and E/A ratio was calculated. LV inflow was recorded by color M-mode, flow propagation velocity (FPV) was measured, and E/FPV was calculated27. Right ventricular diameters, area and area change, and tricuspid annular plane systolic excursion (TAPSE) were measured according to the current guidelines28. Systolic pulmonary artery pressure (sPAP) was estimated from the sum of RV systolic pressure estimated from tricuspid regurgitation velocity and right atrial pressure estimated from inferior vena cava and its collapsibility28.Tissue Doppler was used to calculate the peak longitudinal, systolic and diastolic myocardial velocities in the offline analysis , averaged from six basal segments of the left ventricle, from 2-, 3-, and 4-chamber views. The online S’ and E’ were measured; online E/E’ ratio was calculated as a marker of ventricular filling29. Right ventricular myocardial performance index (MPI) was calculated from the online pulsed tissue Doppler curves of the tricuspid annulus, using the formula MPI = (TCO −  ET)/ET, where TCO is tricuspid valve closure-to-opening time and ET is ejection time28.Speckle tracking was used to assess systolic myocardial deformation in three directions: longitudinal, circumferential, and radial. Peak systolic longitudinal strain (LS) and strain rate (LSR) were calculated as a mean of 18 ventricular segments from the apical views, while peak circumferential strain (CS) and strain rate (CSR), and peak radial strain (RS) and strain rate (RSR) were calculated from 6 ventricular segments from the short-axis view at the level of the papillary muscles30. Right ventricular longitudinal strain and strain rate were determined using the same software originally developed for LV28. LV twist, defined as absolute apex-to-base gradient rotation along the longitudinal axis of the LV, expressed in degrees, was assessed at the short-axis view at the mitral valve level, and the short-axis view at the apical level. Apical and basal rotations were measured, and LV twist was calculated as RotA-RotB. LV torsion was obtained by dividing LV twist to LV end-diastolic longitudinal length (degree/cm)32. LV untwist, a parameter of LV diastolic function, was measured, as well as untwist rate (degree/seconds), as the mean difference between the untwist curves. Finally, left and right atrial functions were also quantified33.Real-time 3D-echocardiography was used to assess left ventricular end-diastolic and end-systolic volumes, ejection fraction, cardiac output, left ventricular mass, and left ventricular strain, using the software 4DLVQ (“4D left ventricle quantification”). The 3 apical views were corrected to display standard 2-, 3-, and 4-chamber views, eliminating the foreshortening. The end-diastolic frame was automatically detected from the electrocardiogram, and three points  were defined manually for each of the three views, and the endocardial border was automatically traced. Then, the endocardial border was adjusted to obtain the optimal tracing. Time-volume curves were generated35.36. Blood pressure and heart rate were monitored. Intima-media thickness (IMT) was measured at the right common carotid artery, 1 cm below bifurcation, using Aloka Prosound α10 ultrasound machine (Japan), with a 7.5 MHz linear array probe. The far wall was used to measure mean IMT, and the final value was averaged from 3 different measurements37. The arterial stiffness was analyzed at the level of the right common carotid artery38. The machine allows measurement of flow velocity simultaneously with the artery diameter, using high-resolution online tracking wall (“E-tracking technology”). Arterial pressure waveforms were obtained, and 5 beats were signal-averaged to give a single waveform of diameter and velocity. Using this waveform, the following parameters were calculated: Peterson’s pressure-strain elastic modulus (Ep), β stiffness index, and local arterial compliance (AC). Augmentation index (Aix) was derived from the diameter-derived pressure waveform. Carotid-femoral pulse wave velocity was measured by Complior System 39. Endothelial function was analyzed by flow mediated dilation, at the level of the right brachial artery, and expressed as a percentage of the baseline diameter41.Subjects were assessed after 10 minutes of rest in the supine position, in a constant room temperature, after 8–12 hours of fasting. Smoking, ingestion of vasoactive medication, caffeine and alcohol was not permitted 4–6 hours before the examination41.Statistical analysis was performed with SPSS software version 20 (IBM Statistics 20). Continuous variables were reported as mean and standard deviation (SD). Categorical variables were reported as percentages. Independent samples T test was used to compare continuous variables, while chi-square test was used to compare categorical variables. Pearson’s correlation was used for the association between variables. Differences with p-values ≤ 0.05 (2-sided) were considered statistically significant. Good reproducibility and repeatability of vascular function parameters were reported previously in our laboratory in 20 consecutive patients by two observers with similar experience for IMT, PWV, and parameters of arterial stiffnessSupplementary Information


We compared three-dimensional speckle tracking echocardiography (3DSTE) and its strain to cardiac magnetic resonance (CMR) with delayed contrast enhancement for left ventricular (LV) chamber quantification and transmurality of myocardial scar. Furthermore, we examined the ability of 3DSTE strain to differentiate between ischaemic and non-ischaemic LV dysfunction.In 80 consecutive patients with ischaemic and 40 patients with non-ischaemic LV dysfunction, the correlations between LV volumes and ejection fraction were measured using 3DSTE and CMR. Global and regional 3DSTE strains and total or percentage enhanced LV mass were evaluated.p = 0.03).LV end-diastolic and end-systolic volumes and ejection fraction correlated well between 3DSTE and CMR . However, 3DSTE significantly underestimated volumes. Correlation for LV mass was modest (r = 0.59). All 3DSTE regional strain values except for radial strain were lower in segments with versus segments without transmural enhancement. However, strain parameters could not identify the transmurality of scar. No significant difference between ischaemic and non-ischaemic LV dysfunction was observed in either global or regional 3DSTE strain except for twist, which was lower in the non-ischaemic group (4.9 ± 3.3 vs. 6.4 ± 3.2°, 3DSTE LV volumes are underestimated compared with CMR, while LV ejection fraction revealed excellent accuracy. Functional impairment by 3DSTE strain does not correlate well with scar localisation or extent by CMR. 3DSTE strain could not differentiate between ischaemic and non-ischaemic LV dysfunction. Future studies will need to clarify if 3DSTE strain and CMR delayed contrast enhancement can provide incremental value to the prediction of future cardiovascular events. Left ventricular (LV) chamber quantification and delineation of myocardial scar are clinically important diagnostic, therapeutic and prognostic parameters –3. To daWe prospectively enrolled 153 consecutive patients with LV systolic dysfunction (EF < 50 % by 2DE) referred for CMR DCE to assess and quantify myocardial scarring. All patients underwent 3DSTE on the same day as the CMR study. Thirty-three patients were excluded: 5 due to irregular heart rhythm, 23 due to poor image quality  and 5 due to very low volume rate with 3DSTE (≤11 volume per second). Of the remaining 120 patients, 80 had ischaemic and 40 had non-ischaemic heart disease. Ischaemic patients were defined by having a coronary angiography showing significant stenosis (>50 % stenosis in ≥1 major coronary artery) or a history of angina, myocardial infarction or coronary revascularisation. Non-ischaemic heart disease was idiopathic LV dysfunction in 36 (90 %), myocarditis in 3 (8 %) and amyloidosis in 1 patient (2 %). All subjects gave informed consent and the local ethics committee approved the study.CMR scans were performed on a 1.5T scanner . ECG-gated cine images were acquired using a breath-hold segmented steady-state free precession sequence. Per patient, 8–10 short-axis views were obtained, starting at the mitral annulus, covering the entire left ventricle. Ten to 15 minutes after injecting 0.2 mmol/kg of a gadolinium-based contrast, enhanced images were acquired in the same orientation as the cine images.All data were analysed on a separate workstation using dedicated software . Endocardial and epicardial contours were manually traced, including the papillary muscles and trabeculations inside the LV cavity. Enhanced regions were then determined after thresholding signal intensity at five standard deviations above the mean signal intensity of remote normal myocardium , 12. All3DSTE imaging was performed from an apical position using a commercial scanner  with a fully sampled matrix array transducer (PST–25SX). Wide-angled acquisitions of 4 sub-volumes were acquired over 5 consecutive cardiac cycles during a single breath-hold, resulting in a mean temporal resolution of 23 ± 3 volume per second range 17–26). Analysis of 3DSTE was done as previously described [7–26. AnaObserver reliability was assessed in 15 randomly selected patients for both 3DSTE and CMR DCE. Datasets were analysed for interobserver reliability by two experienced observers for each technique in a blinded fashion. Intraobserver measures were randomly performed on an average of 1 month apart.t-test, while a Chi-square test or the Fisher’s exact test was used to analyse a difference in categorical variables as appropriate. Inter-technique comparisons between 3DSTE- and CMR-derived LV volumes, EF, and mass included linear regression and Bland-Altman analyses. The significance of differences between the two techniques was tested using paired t-tests. Reliability was assessed using the intraclass correlation coefficient (ICC). The clinical significance of ICC was interpreted as good if ICC ≥ 0.75. A p value < 0.05 was considered statistically significant. All data were analysed using SPSS version 20.0 .Continuous variables are presented as mean ± standard deviation, whereas categorical variables are presented as frequencies and percentages. Differences in continuous variables between the two groups were analysed using the Student’s The patient groups with ischaemic and non-ischaemic LV dysfunction were matched for age and body surface area. However, male gender, hypertension and diabetes mellitus were more frequent in ischaemic patients and the majority of positive DCE studies (89 %) were in the ischaemic patients Table .Table 1Bn = 82) (164 ± 39 vs. 117 ± 36 gm) was modest (r: 0.59). Despite a good correlation for LV volumes, 3DSTE significantly underestimated both volumes with relatively large biases (35–60 ml) and wide limits of agreement (30–67 ml), and significantly overestimated LV mass (bias is 47 g and wide limits of agreement: 38–54 g) and only LVEF has a small bias (0.4 %) and narrow limits of agreement (−0.5–1.3 %). Fig. For global chamber quantification in the whole study population, 3DSTE and CMR LVEF (39 ± 8 vs. 40 ± 7 %), LV end-diastolic (153 ± 54 vs. 213 ± 65 ml) and LV end-systolic volumes (98 ± 53 vs. 133 ± 64 ml) correlated well . Their correlation regarding LV mass (n = 82) correlated poorly with either the total or the percentage enhanced LV mass. These correlations improved non-significantly when applied in the ischaemic group only and became worse in the non-ischaemic group (Table n = 1689) were classified according to the result of CMR DCE as follows: group A with 0 % hyperenhancement (n = 864), group B with non-transmural hyperenhancement , and group C with transmural hyperenhancement . The majority of enhanced segments were in the ischaemic group . On this regional level, the correlations between 3D strains and the percentage of myocardial scar were poor as well, and this was true for both the segments with (r = 0.09 to 0.24) or without (r = 0.01 to 0.08) transmural hyperenhancement. By dividing the segments into three groups  the correlations between different types of strain in each group and the percentage of myocardial scar were poor with better correlations for apical strains .Global 3DSTE strains in ischaemic and non-ischaemic patients with positive DCE n = 8 correlatp = 0.02 for both). In addition, it defined lower values for all strain components except radial strain in segments with versus those without transmural hyperenhancement . However, the yielded AUC for all strain parameters was low for differentiation of transmural from non-transmural enhanced segments, with circumferential stain and area strain performing best (r = 0.67 for both).In segments showing hyperenhancement in ischaemic and non-ischaemic patients, 3DSTE could define lower values for circumferential strain and area strain in segments with non-transmural hyperenhancement compared with non-enhanced segments  to differentiate between the two groups Table .Table 43The intra- and inter-observer reliability for assessment of LV volumes, mass and EF using 3DSTE were excellent. However, intra-observer reliability was better than inter-observer reliability for assessment of different strain components. For the assessment of LV volumes, EF, mass, enhanced and percentage enhanced mass using CMR, both the intra- and inter-observer reliability were excellent Table .Table 5R3DSTE represents a major innovation towards more comprehensive LV quantification, including principal indices as LV volumes and EF, but also parameters directly assessing global and regional myocardial function using strain. The aim of this study was to test the ability of 3DSTE to provide accurate and rapid chamber quantification and viability assessment as compared with CMR DCE.Despite their good correlation, 3DSTE significantly underestimated both LV volumes and overestimated myocardial mass compared with CMR. The potential reasons for these known discrepancies were thoroughly discussed in our previous work . Therefon = 25). Although they stated that both are well correlated, their reported Pearson’s correlation coefficients were all <0.5, which should be interpreted as moderate to poor correlation from both a statistical and a clinical point of view. Furthermore, our findings are supported by a recent similar study in 58 ischaemic patients using 3DSTE equipment by a different vendor, which reported moderate to poor correlations for both global and regional 3DSTE strains [3DSTE strain evaluates the functional consequences of myocardial fibrosis and CMR DCE evaluates its mere anatomical extent. For global 3DSTE strain, the agreement between global 3DSTE strains and CMR DCE was poor. These findings are in line with previous studies reporting that 2DSTE global longitudinal strain is markedly attenuated regardless of the extent of myocardial fibrosis as delineated by CMR DCE . In addi strains .For regional 3DSTE strain, previous studies using Doppler strain and 2DSTE in this regard have shown mixed results –21. In tIt is well established that the longitudinal myocardial mechanics are mainly governed by the subendocardial longitudinally arranged fibres and the circumferential mechanics are mainly dependent on the midmyocardial circumferentially arranged fibres . LikewisCurrent limitations of 3DSTE are the relatively low spatial and temporal resolution and unreliable acquisition in the presence of ab irregular heart rhythm, which lead to limited feasibility. In addition, the current lack of standardisation among different ultrasound machines and software packages provided by different vendors may preclude generalisation of our results . However3DSTE-derived LV volumes are underestimated compared with CMR, while measurement of LVEF revealed excellent accuracy. Functional impairment by 3DSTE strain does not correlate well with scar localisation or extent by CMR. In addition, 3DSTE strain could not differentiate between ischaemic and non-ischaemic LV dysfunction. Future studies will need to clarify whether 3DSTE strain and CMR DCE can provide incremental value to the prediction of future cardiovascular events.


Myocardial inflammation and injury occur during coronary artery bypass graft (CABG) surgery. We aimed to characterise these processes during routine CABG surgery to inform the diagnosis of type 5 myocardial infarction.We assessed 87 patients with stable coronary artery disease who underwent elective CABG surgery. Myocardial inflammation, injury and infarction were assessed using plasma inflammatory biomarkers, high-sensitivity cardiac troponin I (hs-cTnI) and cardiac magnetic resonance imaging (CMR) using both late gadolinium enhancement (LGE) and ultrasmall superparamagnetic particles of iron oxide (USPIO).n = 18) of patients although clinical peri-operative type 5 myocardial infarction was diagnosed in only 9% (n = 8). LGE was associated with the delayed 24-h peak in hs-cTnI and its magnitude correlated with AUC plasma hs-cTnI concentrations  but not systemic inflammation, myocardial inflammation or bypass time.Systemic humoral inflammatory biomarkers  increased in the post-operative period with C-reactive protein concentrations plateauing by 48 h (median area under the curve (AUC) 7530 [interquartile range (IQR) 6088 to 9027] mg/L/48 h). USPIO-defined cellular myocardial inflammation ranged from normal to those associated with type 1 myocardial infarction (median 80.2 [IQR 67.4 to 104.8] /s). Plasma hs-cTnI concentrations rose by ≥50-fold from baseline and exceeded 10-fold the upper limit of normal in all patients. Two distinct patterns of peak cTnI release were observed at 6 and 24 h. After CABG surgery, new LGE was seen in 20%  contains supplementary material, which is available to authorized users. Approximately 400,000 coronary artery bypass graft (CABG) operations are performed each year in the United States of America . CardiopThe universal definition of myocardial infarction defines procedural (type 5) myocardial infarction as a > 10-fold elevation above the 99th centile of cardiac troponin within 48 h of CABG surgery accompanied by new pathological Q waves or left bundle branch block, angiographically documented new graft or new native coronary artery occlusion, or imaging evidence of new loss of viable myocardium or new regional wall motion abnormality . Pa. Pa15]. p = 0.04; Fig. Complete cTnI profiles over 48 h were available in 84 patients. Plasma cTnI concentrations peaked at 6 h  or 24 h  or cross clamp time (r = 0.02 p = 0.43).Two patterns of cTnI release were noted in the post-operative period with peak concentrations at 6  or non-specific pericarditic change  and T wave inversion . Patients with ECG evidence of infarction exhibited a cTnI peak at 24 h: 6-h mean, 6124 ng/L  and 24-h mean 23,410 ng/L . Patients without specific ECG changes of infarction (n = 74) had peak cTnI concentrations at 6 h: 6-h mean 5186  ng/L and 24-h mean 1905  ng/L.Eleven (13%) patients developed new ST-change/new bundle branch block/new Q-waves consistent with myocardial infarction Fig. . The majOverall, 7/11 (64%) of patients with an ECG suggesting infarction had a rise in cTnI concentration between 6 and 24 h. In patients with no evidence of infarction on ECG, only 11/74 (15%) had a rise in cTnI concentration between 6 and 24 h. Thus ECG analysis provided a positive predictive value of a late troponin peak of 64%  and a negative predictive value of 85% . An ECG demonstrating infarction was 23% sensitive and 98% specific for the formation of LGE.r = 0.33, p < 0.01). For left ventricular function, 8/68 (12%) of patients had at least 5% increase in ejection fraction, 20/68 (29%) had a decrease and 40/68 (59%) had no change  with ST-change/new bundle branch block/new Q-waves, 7/35 20%) with no ECG changes, 3/17 (18%) with pericarditic changes and 0/10 (0%) with T wave inversion  ng/L and 24-h mean 9073  ng/L. By contrast, patients without new LGE had a peak cTnI concentration at 6 h of 5487  ng/L compared to a mean of 1545  ng/L at 24 h. Overall 6/13 (46%) of patients with new LGE had a rise in cTnI concentration between 6 and 24 h compared to 5/52 (10%) in patients without LGE (p < 0.01). A rise in troponin release after 6 h was 46% sensitive (95% CI 19 to 75) and 90% specific  for detecting new LGE. The positive predictive value was 55%  and the negative predictive value 87% .We believe this is the first in depth and detailed investigation of high-sensitivity cardiac troponin release and perioperative myocardial inflammation, injury and infarction in patients undergoing CABG surgery. This study was performed on a highly characterised and phenotyped population using the current gold standard techniques to detect myocardial inflammation, injury and infarction . We haveUsing the latest generation high-sensitivity assay, we have shown that cTnI release is >10-fold the upper limit of normal (99th centile) in all patients following CABG surgery. Importantly, we describe two patterns of release with an early 6-h peak and a more delayed 24-h peak. We suggest these peaks reflect perioperative myocardial injury and infarction respectively as demonstrated by late gadolinium enhancement on cardiac magnetic resonance imaging. There appears to be no single discriminatory threshold for troponin concentration that could reliably discriminate clinically overt myocardial infarction. Our data indicate that the profile, rather than peak, of troponin release may be more important when attempting to distinguish between myocardial injury and type 5 myocardial infarction.All patients in our study exhibited at least 50-fold rise from baseline troponin and all but 4 had at least 100-fold increase. Many factors contribute to myocardial injury in the perioperative period including manipulation of the heart during on-pump surgery, cardioplegia, ischemia and patients specific factors including severity of underlying coronary artery disease and myocardial function. The average increase in cTnI concentration from baseline was nearly 2000. The third universal definition for type 5 myocardial infarction occurring during CABG surgery stipulates a cardiac marker elevation of ≥10-fold the upper limit of normal (99th centile). In our study, all patients undergoing on-pump surgery fulfil this criterion and this threshold is therefore unhelpful and has no value. This leads to the questions of whether a higher single threshold should be employed or whether alternative criteria looking at the profile of cTnI release may be more discriminatory.Our data would not support the approach of increasing the troponin threshold to be more discriminatory. For example, increasing the threshold to >100-fold 99th centile would have excluded 64% of patients with LGE proven macro-infarction and included 43% of patients without. Our data support the findings by other groups that multiple time-point sampling to detect a late rise in troponin concentration is more discriminatory for type 5 myocardial infarction –20. SelvA previous study reported new LGE in up to 78% of patients undergoing CABG surgery, but the investigators did not perform pre-operative CMR . We idenAlthough it might have been anticipated that the magnitude of myocardial injury would correlate with CPB time, there was no association with AUC cTnI release. Furthermore there was no correlation with inflammatory cytokine release or myocardial inflammation. This suggests that injury is not mediated by inflammation alone. Other processes influence the cTnI injury such as microemboli, surgical manipulation of the heart and patient specific factors. Our data also confirm that substantial cTnI release occurs in the perioperative period without imaging evidence of infarction and new scar formation consistent with reversible myocardial injury.We used USPIO contrast for the first time to assess in vivo myocardial inflammation following CABG surgery, similar to macrophage infiltration in patients with type 1 myocardial infarction . The aveOur study has some limitations. This was a sub-analysis of the EMPIRE study . In thisAll patients undergoing CABG surgery demonstrate >10-fold elevation above the 99th centile of cardiac troponin indicating the current universal definition of type 5 myocardial infarction lacks specificity. Differing levels of myocardial inflammation post CABG surgery occurred, and did not correlate directly with the length of CPB, hs-cTnI release or circulating cytokines. A peak hs-cTnI at 6 h following CABG appears to be related to the surgical process and non-specific myocardial injury whilst a continuing increase at 24 h suggesting myocardial infarction. We would suggest cTnI sampling at 6 and 24 h post CABG surgery together with ECG assessment for the routine detection and diagnosis of type 5 myocardial infarction.Additional file 1:Systemic inflammatory markers. (DOCX 387 kb)Additional file 2:Correlations and change in ejection fraction (pre to post surgery). (DOCX 176 kb)


Becker muscular dystrophy (BMD) is allelic with Duchenne muscular dystrophy and represents a milder skeletal muscle phenotype; however, cardiac dysfunction remains a significant clinical problem. Cardiac involvement in BMD precedes skeletal muscular decline, and cardiomyopathy often leads to death before the age of 60 years. Cardiac magnetic resonance (CMR) is used for ventricular function assessment and myocardial tissue characterization. Late gadolinium enhancement (LGE) in BMD patients is interpreted as a sign of irreversible macrofibrosis, and often prompts changes in cardiac management to try and limit fibrosis progression. T1 mapping is a more sensitive biomarker of diffuse microfibrosis and may offer an opportunity for earlier therapeutic intervention. Currently, myocardial T1 values in BMD patients are unknown. The purpose of this study is to measure T1 values in BMD patients to determine the prevalence of diffuse myocardial microfibrosis, and its relation to LGE and cardiac dysfunction.Twenty-nine BMD patients  underwent CMR for assessment of ventricular function and gadolinium-based tissue characterization. Native myocardial T1 time and post-contrast myocardial T1 ratios  were analyzed and compared to published normal values. Additionally, native T1 values and post-contrast myocardial T1 ratios were compared between BMD patients with and without LGE.Mean native T1 values were significantly prolonged in BMD patients compared to published normal values . In addition, the post-contrast T1 ratio  was significantly decreased in BMD patients compared to published normal values . Approximately 31% of BMD patients were positive for LGE, with the basal and mid-ventricular inferolateral segments being the most commonly involved. In BMD patients without LGE, native T1 times remained significantly prolonged and post-contrast T1 ratios remained significantly decreased (p ≤ 0.001 for both). Despite the universally abnormal T1 values, only 14% of BMD patients had evidence of LV dysfunction with an ejection fraction < 55%. Extracellular volumes (ECV) based on T1 mapping results were unable to be calculated due to lack of patient hematocrit data in relation to date of scan.T1 mapping in BMD patients demonstrated abnormal pre- and post-contrast T1 values suggesting diffuse myocardial fibrosis and was a more sensitive marker of fibrosis compared to LGE. Detecting diffuse microfibrosis prior to development of scar and cardiac dysfunction could allow for earlier antifibrosis treatment initiation, which might improve cardiovascular morbidity and mortality in the muscular dystrophy population.


Pulmonary hypertension (PH) is associated with a metabolic shift towards glycolysis in both the right ventricle and lung. This results in increased glucose uptake to compensate for the lower energy yield of glycolysis, which creates a potential for 2-[18F] fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) to be a useful tool in the evaluation of participants with PH. We investigated the utility of PET for PH by comparing FDG-PET uptake in the right ventricle and lungs in 30 participants with PH and eight healthy controls and correlating these measurements with echocardiographic (ECHO) measurements and other traditional assessments commonly used in PH. All participants underwent gated FDG-PET scanning in the fasting state, ECHO, six-minute walk test (6MWT), and blood draw for NT-proBNP. Participants also completed the CAMPHOR questionnaire. Right ventricular (RV) end-diastolic and end-systolic volumes, RV ejection fraction, and FDG uptake by PET were significantly different between PH and healthy controls and strongly correlated with plasma NT-proBNP levels and RV ECHO parameters including TAPSE, RV systolic pressure, Tei index, and global peak systolic strain. In addition, lung standardized uptake value (SUV) was also found to be significantly higher in participants with PH than healthy controls. However, lung SUV did not show any significant correlations with NT-proBNP levels, 6MWT, or functional and pressure measurements by ECHO. In this study, we demonstrated the ability to evaluate both lung and right heart metabolism and function in PH by using a single gated FDG-PET scan. This requires increased glucose uptake to compensate for the lower energy yield of glycolysis. In PH, there is also increasing evidence for a pathologic metabolic shift to glycolysis in the absence of ischemia in both the lungs and heart.311 This metabolic shift to a glycolytic pathway creates further potential for 2-[18F] fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) to be a useful tool in the evaluation of RV metabolism and function and pulmonary vascular changes seen in PH.Pulmonary hypertension (PH) results in abnormalities of right ventricular (RV) morphology and function as a direct consequence of pressure and volume overload of the right ventricle. Changes in RV morphology include hypertrophy, increased end-diastolic muscle fiber length, and dilation. These changes are associated with decreased RV capillary density and decreased right coronary artery perfusion pressure (associated with increased RV systolic pressure and RV mass) making the RV myocardium more vulnerable to ischemia.Using gated FDG-PET, we performed metabolic and functional imaging of the heart and metabolic imaging of the lungs in participants with PH and healthy controls. We correlated quantitative PET measurements with echocardiographic (ECHO) measurements and other traditional assessments commonly used in PH.This study was approved by the Cleveland Clinic Foundation Institutional Review Board, and written informed consent was obtained from all participants. At least 30 individuals with PH were targeted to enroll because of the pilot nature of this study. The diagnosis of PH was confirmed by historical right heart catheterization. Participants were required to have a resting mean pulmonary artery pressure (mPAP) ≥25 mmHg and a pulmonary artery occlusion pressure (PAOP) ≤12 mmHg. Individuals with World Heath Organization group 2 PH (secondary to left heart disease) were excluded from the study. All participants underwent transthoracic echocardiography, a gated FDG-PET scan, six-minute walk test (6MWT), and blood draw for N-Terminal pro-brain natriuretic peptide (NT-proBNP) . Each individual also answered the Cambridge Pulmonary Hypertension Outcome Review (CAMPHOR) questionnaire. All clinical, imaging, and laboratory data were obtained on the same day for each individual. Healthy controls undergoing FDG-PET scans were volunteers without history of chronic disease or medication use.PET metabolic images were acquired with the individuals in the fasting state for a minimum of 8 h. A 370 MBq (10 mCi) dose of 18F-FDG was administered intravenously. Data were acquired on a PET/CT scanner  after a prescribed 90-min uptake period prior to imaging . The 22-cm axial field of view was positioned to include the heart and most of the lungs. A low-dose CT scan was acquired  for the purpose of PET attenuation correction. During the CT scan, the individual was instructed to hold his/her breath at near-end expiration in order to optimize anatomic matching with the free-breathing PET scan. PET data were then acquired for 15 min in list mode along with the ECG-gating signal. An initial static image was reconstructed to assess image registration and to allow for adjustment of CT alignment, if necessary. After verifying CT alignment, static PET images and eight-frame gated PET images were reconstructed as follows: iterative OS-EM algorithm with time-of-flight and resolution modeling (Ultra-TrueX) three iterations, 21 subsets, 6-mm Gaussian post-filter, 128 × 128 matrix, 1.8 zoom.End-diastolic (ED) and end-systolic (ES) PET images were extracted from the gated PET dataset by summing frames 1 and 8 for ED and frames 4 and 5 for ES Images. Summing the frames improved image quality and improved the ability to determine the myocardial boundary in many cases. The inner surface of the RV volumes were delineated manually on ED and ES images using the 3D Brush contouring tool of an image processing workstation , allowing for calculation of the RV ejection fraction (RVEF) .Fig. 1.Fused PET/CT images were analyzed quantitatively by a single-blinded radiologist (DRN). PET/CT scan overlay facilitated accurate drawing and positioning of regions of interest on static cardiac FDG-PET images for analysis of standardized uptake value (SUV) in the left ventricular (LV) free wall, interventricular septum, RV free wall, and right atrial (RA) free wall. Maximum PET SUV was recorded in the RV, RA, and LV free walls and the interventricular septum. RV/LV SUV ratio was calculated from these measurements.M was the measured SUV, without concern for the various lung components; (2) SUVL was the SUV corrected for the volume fraction of air only, which represents the mean uptake in bulk lung material, calculated according to SUVL = SUVM/(1 + HU/1000); (3) SUVT was the SUV corrected for the volume fractions of air and blood, which represents the mean FDG uptake in lung tissue . The average blood fraction in lung  was estimated to be 16% based on previously reported measurements in dogs.13 SUVT was then calculated according to SUVT = (SUVM – 0.16 SUVB)/(1 + HU/1000 – 0.16), where SUVB was the blood pool SUV measured as the mean SUV of the LA cavity and the descending thoracic aorta. When drawing regions, caution was taken to avoid including adjacent structures that would have affected quantitative results. For example, regions outlined in the lung did not include large blood vessels, and regions drawn for blood pool measurements only included the central portion of the cavity.In order to assess lung FDG uptake, a total of 24 regions per individual were analyzed, located in the upper/mid/lower levels and anterior/posterior regions of each lung. Mean CT Hounsfield Units (HU) and mean PET SUV were recorded for each region. Mean SUV of the lung was calculated as the average over these 24 regions. Lung FDG uptake was quantified in three ways: (1) SUVA comprehensive transthoracic Doppler echocardiogram  was performed by a single registered advanced cardiac sonographer (MP) and included standard two-dimensional (2D) imaging, m-Mode, tissue and spectral Doppler for assessment of RV size, function, and right heart hemodynamics. All measurements were averaged over three cardiac cycles. Heart rate was calculated from an average of three R-R intervals. Blood pressure, height, and weight were recorded just prior to imaging. RV lateral annular pulsed wave tissue Doppler imaging was recorded from the basal segment. Annular peak systolic velocity (S’) served as a measure of RV function.15 RV end-diastolic (RVED) and RV end-systolic (RVES) basal diameters were measured at the level of the tricuspid annulus. RV fractional shortening was calculated from RVED and RVES areas using the formula (RVED area - RVES area)/RVED area ×100%. Tricuspid annular plane systolic excursion (TAPSE) was calculated using m-mode echocardiography with cursor placement parallel to the RV lateral free wall. Right atrial volumes were measured at peak systole when the RA was largest in size. RA pressure (RAP) was estimated based on inferior vena cava size and compressibility with normal respiration and during sniff testing per ASE guidelines.15 Pulsed wave Doppler flow of the hepatic veins was evaluated for systolic reversal. RV wall thickness was measured in the subcostal window apical four-chamber view during end-diastole at the TV annular level. If the subcostal window was not adequate, the apical four-chamber view was used.The following right heart functional parameters were analyzed from an apical four-chamber view modified to focus on the RV per the American Society of Echocardiography (ASE) guidelines.2 plus estimated RAP in the absence of pulmonic stenosis and RV outflow tract (RVOT) obstruction.The tricuspid valve (TV) was interrogated for flow abnormalities with color flow and spectral Doppler with particular attention focused on the TV regurgitation (TR) peak velocity recorded from multiple imaging sites. Images were enhanced with agitated saline contrast as needed to optimize measurement of peak TR velocity. RV systolic pressure (RVSP) was calculated using the peak TR velocity (V) and the simplified Bernoulli equation, RVSP = 4VFrom the parasternal window, proximal RVOT linear dimensions were measured at the level of the pulmonic valve (PV) annulus. Pulsed wave Doppler was measured just proximal to the PV, with the closure snap clearly identified to derive the RVOT time velocity integral (TVI) and RV ejection time. RV Tei index or the RV index of myocardial performance (RIMP) was calculated as TV closing to opening time minus RV ejection time, divided by the RV ejection time. Pulmonary vascular resistance (PVR) was derived by the equation TRV/TVI (RVOT) × 10 + 0.16.From the apical four-chamber window, 2D speckle tracking images of the LV and RV (RV focused view) were obtained at a frame rate of 50–70 frames/s (fps). RV longitudinal global peak systolic strain (RVPSS) was analyzed offline using Echo Pac Clinical Workstation Software . RV global longitudinal strain was calculated using three lateral RV wall segments and three inter-ventricular septum segments.All participants completed a 6MWT that was conducted according to ATS guidelines. Heart rate recovery was measured as difference between heart rate at 6 min and 1 min after completion of the walk. Participants completed the PH-health related quality of life CAMPHOR questionnaire. Individuals also had blood drawn to determine plasma NT-proBNP levels, which were determined by electrochemiluminescence sandwich immunoassay.P = 0.05. A correction for multiple comparisons was not performed since this was a pilot study with a small sample size.Student t-test or pooled t-test was used to compare hemodynamic and imaging parameters between the individuals with PH and healthy controls where appropriate. Spearman correlation was calculated for RVED, RVES volumes, RVEF, and pulmonary and cardiac FDG uptake values versus clinical, laboratory, and ECHO parameters. Intra-rater variability was assessed with the Bland–Altman method. Statistical significance was accepted at a level of P = 0.2, 95% confidence interval [CI] = –4.5 to 19.9)  . Of the Intra-rater agreement was evaluated for SUV measurements and showed almost no mean difference (difference mean −0.059 and 95% limits of agreement of 0.006 and −0.126) with high correlation coefficient (0.992).P = 0.54), between the right and left lung (P = 0.23), or between the upper and lower lobes of each lung (P = 0.17). Thus, we calculated the average SUV by including all levels of both lungs.There was no statistically significant difference in FDG uptake in the 12 different lung regions for each lung (M (not corrected for air or blood components) of individuals with PH (0.50 ± 0.15) was significantly higher than in healthy controls  (P = 0.008). On the other hand, SUVL (corrected for air component only) of PH and healthy controls was not significantly different (P = 0.10) (P = 0.15). SUVT (corrected for air and blood components) of all lung segments was significantly higher in individuals with PH than healthy controls (P = 0.03) (P = 0.056). Because of the heterogeneity of our study population, we also performed a subanalysis comparing lung SUVT of the patients with idiopathic and/or hereditary PAH with healthy controls and found that SUVT was significantly higher in patients with idiopathic (n = 9) and hereditary (n = 12) PH (2.04 ± 0.73) than healthy controls (1.59 ± 0.38) (P = 0.04). In addition, comparison between idiopathic (2.13 ± 0.63) and hereditary PAH (1.98 ± 0.81) cases did not show significant difference (P = 0.6).Average lung SUV = 0.01) . When th = 0.10) , and thi = 0.03) . ExclusiM , SUVL , and SUVT . Similarly, heart rate recovery did not correlate with average lung SUVM , SUVL , or SUVT . CAMPHOR total score was not correlated with average lung SUVM , SUVL , or SUVT . NT-proBNP levels also did not correlate with average lung SUVM , SUVL , or SUVT .Distance achieved during the 6MWT did not correlate with any of the pulmonary SUV measures: average lung SUVP = 0.0006). Also, comparison between idiopathic (1.20 ± 0.75) and hereditary PAH (1.49 ± 1.23) cases did not show a significant difference (P = 0.5). RV/LV SUV ratio significantly correlated with RA volume and RAP, RVES and RVED areas, RVES and RVED diameters, RV fractional shortening, RV systolic pressure (RVSP), TAPSE, and RV global peak systolic strain, whereas it did not correlate with RV thickness, RV Tei index, and S′ , heart rate recovery , or total score on the CAMPHOR questionnaire . RV/LV SUV ratio also did correlate significantly with plasma NT-proBNP levels   except RVEF. Also, a comparison between idiopathic and hereditary PAH cases did not show a significant difference .RVED, RVES volumes, RVEF, and RV stroke volume measured from gated FDG-PET images were all significantly higher in individuals with PH compared with healthy controls . HoweverPET RVED and RVES volumes significantly correlated with a number of ECHO parameters including: RA volume, RVES and RVED areas, RVES and RVED diameters, RV fractional shortening, RV Tei index, RVSP, RV global peak systolic strain, S′, and PVR. Strain values were not derived in two individuals due to technical complications in data transfer for one and poor technical quality of the RV image for the other. A correlation was not found with RV thickness and TAPSE . PET RVEP = 0.6, 0.5, 0.2, 0.6, respectively), heart rate recovery , or CAMPHOR total score . However, RVED and RVES volumes and RVEF significantly correlated with plasma NT-proBNP levels, whereas RV stroke volume did not .PET-derived RVED and RVES volumes, RVEF, and RV stroke volume were not significantly correlated with 6MWD ( did not . NT-proBP = 0.4), RA volume , RVED diameter , RV Tei Index , RV thickness , right atrial pressure , TAPSE , and RV global peak systolic strain . Nevertheless, there was a significant correlation with RV systolic pressure .Of note, plasma NT-proBNP level did not correlate with a number of echocardiographic features including: RVOT ejection time  is critical to the success of kinetic modeling. Typically, the AIF is obtained by repeated sampling of arterial blood and measurement of radioactivity with correction for metabolites. A desirable alternative is image-based measurement of AIF, which greatly simplifies the procedure; however, use of an image-based AIF may cause errors that significantly affect kinetic analysis. For example, in their study comparing pulmonary FDG uptake in IPAH, Ruiter et al. acquired dynamic images with the intent of measuring metabolic rate of glucose uptake by Patlak analysis using an image-based AIF, but they obtained negative results and had to abandon the dynamic data.16 Our simplified protocol uses static image quantification with 90-min uptake period and with certain assumptions in the normalization for air and blood. Although less quantitative than full kinetic modeling with blood sampling, this approach requires significantly less resources and is much more easily implemented.An underlying goal of our approach was to utilize a PET scan protocol that is feasible to acquire in many clinical laboratories. Much progress has been made toward absolute quantification of lung PET images with kinetic modeling.8 Following this finding, Marsboom et al. demonstrated that pulmonary FDG uptake increases with the earliest onset of PH in a monocrotaline rat model of PH and decreases after treatment with imatinib and dichloroacetate, two effective metabolic therapies for PH.9 We, and others, identified that this primarily occurs within the endothelium and vascular smooth muscle.810 Subsequently, the relationship between pulmonary FDG uptake and PH severity was investigated using both fasting and non-fasting PET scans.16 Ruiter et al. performed the first study investigating the correlation between pulmonary FDG uptake and PH severity, and no correlation was found between lung FDG uptake and 6MWD, mPAP, PVR, and plasma NT-proBNP levels, similar to our results.16 Although average lung SUVM in controls agreed between their study and ours (0.37 versus 0.37), average lung SUVM in PH participants was lower in their study compared with ours . Possible explanations include differences in uptake time prior to scanning (50 versus 90 min) and proportion of PH subtypes (IPAH versus heterogeneous) in study populations.We previously demonstrated that there is a higher fasting FDG uptake in the lung of participants with PH compared with healthy controls.17 Thirty individuals with PH underwent FDG-PET scans after oral glucose load and fatty acid inhibition. RV/LV FDG uptake ratio correlated with functional class and severity of PH as measured by Tei index; however, it did not correlate with PVR. In another study of interest, Can et al. compared RV/LV SUV ratio in participants with PH and healthy controls and examined its relationship with ECHO parameters and the 6MWT.4 The RV/LV SUV ratio was significantly higher in individuals with PH than healthy controls  and was significantly correlated with pulmonary arterial systolic pressure, TAPSE, RV Tei index, and 6MWD. Oikawa et al. demonstrated that RV SUV was significantly correlated with mPAP, RAP, PVR, RV wall stress, and plasma BNP levels, but not with RV wall thickness and mass in 24 participants with PH.18 After three months of treatment with epoprostentol in ten of these participants, RV SUV was significantly decreased in those participants with a documented 30% or greater improvement in PVR. Furthermore, the percentage change of RV FDG uptake significantly correlated with improvement in PVR and RV systolic wall stress. Likewise, Fang et al. showed a significant improvement in RV/LV FDG uptake ratio after six months of treatment with sildenafil. Overall, these findings suggest that RV/LV SUV ratio may be a strong predictor of PH severity and may be useful to monitor response to treatment.19 Lastly, Tatebe et al. examined the relationship between RV/LV ratio and prognosis of PH.20 They included 27 individuals with PH who underwent gated FDG-PET scan using an oral glucose loading protocol, and followed them for 69 ± 49 months. They demonstrated that higher RV FDG update was associated with shorter time to clinical worsening and higher all-cause mortality, indicating that elevated RV SUV might be a potential prognostic marker in the management of PH.RV failure is the major cause of mortality in individuals with PH. Therefore, non-invasive imaging techniques of the right ventricle are needed to help improve outcomes. A number of studies have explored the potential utility of FDG-PET uptake in the RV to improve diagnosis, management, and prognostication of participants with PH. In one of the first studies done in humans, Kluge et al. examined the relationship between RV/LV glucose uptake ratio and PH severity.Our study found that RV/LV FDG uptake ratio correlated with RA volume and RAP, RVES and RVED areas, RVED and RVES diameters, RV fractional shortening, RVSP, TAPSE, and RV global peak systolic strain. We did not find a correlation between RV/LV SUV ratio and 6MWD, CAMPHOR score, RV thickness, RV Tei index, and S′. These results are consistent with the literature as summarized above. An important distinguishing feature of our study is that unlike prior PET studies for PH performed under glucose load to maximize FDG uptake, the PET scans in our study were performed in the fasting state, which may account for some of the differences in our data. We demonstrated the feasibility of fasting FDG-PET in assessing RV metabolic activity, and our data suggest that it may allow for a deeper understanding of the metabolic mechanisms that lead to PH. Another distinguishing feature of our study is the use of gated PET acquisition to obtain functional cardiac measurements in addition to the metabolic evaluation of the lung and myocardium.21 However, in that study, individuals were imaged under oral glucose load in order to increase myocardial FDG uptake and to facilitate automated identification of RV wall boundaries.Commercial software is available for automated cardiac PET analysis of LV regional myocardial perfusion, volume, EF, and wall motion. Wang et al. showed that by applying one such commercial software package to the RV instead of the LV, FDG-gated PET scan calculations of RVED and RVES volumes, and RVEF significantly correlated with similar measurements performed with cardiac MRI and cardiac CT.In our study, automated software failed to identify myocardial boundaries and manual processing was required. Our manual measurements of RV volumes and ejection fraction correlated significantly with RV echocardiographic parameters. A limitation of this technique is that the ability to determine myocardial wall boundaries from gated PET images depends highly on the degree of FDG uptake, which is lower in the fasting state compared with glucose-loaded state, as well as the level of image noise. Since each frame of an eight-frame gated PET image has one-eighth the counts as the corresponding static image, obtaining high quality ED and ES images can be challenging. For this study, we were fortunate to use a state-of-the-art PET scanner with an extended axial field of view, high count sensitivity, and time-of-flight capability. These features enabled the heart and lungs to be scanned simultaneously and with high image quality. Summing two of the eight frames improved ED and ES image quality. Even with improved count statistics from summing two frames, there were a few cases (6/30 PET scans) in which there was insufficient uptake above the noise level to determine myocardial wall boundaries in the ED and ES PET images. Considering that many PET scanners do not have time-of-flight capability and high count sensitivity, it is possible that myocardial wall determination might be more challenging or less accurate in some cases.Although the difference in lung FDG uptake was small between PH participants and controls, it was sufficient to reach statistical significance in this population. However, lung SUV measurement does not appear to be sufficiently accurate to characterize PH severity in a single patient, and clinical use of lung SUV is unlikely. Cardiac RV/LV uptake ratio, on the other hand, showed much larger variation between PH participants and controls, and among PH participants themselves. Further study is needed to understand the underlying mechanisms. Potentially, differences or changes in RV/LV ratio may be sufficiently large to be useful in research studies or in a clinical environment. Functional parameters derived from cardiac PET images correlated strongly with ECHO parameters. ECHO’s simplicity, lower cost, and lack of ionizing radiation still make it most suitable for clinical use. RV functional parameters from three-dimensional (3D) PET may be potentially more accurate than 2D ECHO; however, this awaits further investigation with comparison to the gold standard, cardiac 3D MRI.In conclusion, gated FDG-PET offers both metabolic and functional evaluation of the heart and metabolic evaluation of the lungs for PH during a single imaging procedure. Lung SUV measurements were higher in PH than healthy controls, confirming prior results in the literature. Myocardial SUV measurements (RV/LV SUV ratio) strongly correlated with PH severity and may be useful for monitoring treatment response. Although imaging in the fasting state does not produce the highest myocardial uptake of FDG, there usually was sufficient uptake to allow for accurate 3D segmentation of the RV at ED and ES allowing for functional analysis. Our gated FDG-PET measurements of RV function correlated strongly with 2D ECHO measurements. Nevertheless, patient preparation is a topic for future research, as most published work on FDG imaging of the lung was done in the fasting state, whereas most FDG imaging of the heart was done in the glucose-loaded state.