The aim of our study was to investigate changes in cardiac index and left ventricular end-diastolic volume in a steep had-down tilt. This is a prospective observational study. We investigated the influence of steep head-down tilt on cardiac function and hemodynamics without fluid restriction in 12 men of American Society of Anesthesiologists physical status I–II undergoing robot-assisted laparoscopic prostatectomy. We measured left ventricular ejection fraction, left ventricular end-diastolic volume and cardiac index by transesophageal echocardiography, cardiac index using a FloTrac® sensor. Left ventricular ejection fraction decreased, whereas cardiac index and left ventricular end-diastolic volume did not change, indicating that steep head-down tilt and pneumoperitoneum during robot-assisted laparoscopic prostatectomy did not greatly influence cardiac function.The following variables changed significantly after tilting and establishment of the pneumoperitoneum: left ventricular ejection fraction , systolic blood pressure  and diastolic blood pressure . There were no significant changes in cardiac index or left ventricular end-diastolic volume measured by transesophageal echocardiography, or cardiac index by FloTracThis study was registered as a clinical study with the Japanese Official Clinical Trial Registry  Robot-assisted techniques have gained popularity because they overcome several of the shortcomings of conventional laparoscopic techniques. The problems associated with robotic prostatectomy are a consequence of four main factors: the steep Trendelenburg position of the patient, the insufflation of carbon dioxide to produce a pneumoperitoneum, spatial restrictions because of the bulk of the equipment set over the patient, and the possibility of unexpected visceral injury or blood loss .A few cases of cardiopulmonary deterioration, evidenced by pulmonary edema, pulmonary embolism and worsening of mitral regurgitation, have been reported during this procedure –4. We in® operating table,  and with the da Vinci® Surgical System .The study protocol was approved by the Ethics Committee of Osaka Medical College (Reference Number 1339), and all participants provided written informed consent. This study was registered as a clinical study with the Japanese Official Clinical Trial Registry . Twelve men scheduled for RALP under general anesthesia were assessed in this prospective observational study. All subjects were selected after routine screening and all met the criteria for American Society of Anesthesiologists (ASA) physical status classification I–II. Routine preoperative evaluation included electrocardiography, chest radiographs, hematocrit and a screening chemistry panel to aid in identifying underlying myocardial ischemia, chronic obstructive pulmonary disease, anemia and hyperglycemia. Patients with cardiac disease, including dysrhythmia and coronary artery disease, and those with moderate or severe obstructive pulmonary disease, did not meet the criteria for this study. All RALP procedures were performed on the same ALPHAMAXX2O was provided. After induction of anesthesia, ventilation was adjusted to achieve an end-tidal carbon dioxide tension of 32–36 mmHg. If oxygen saturation measured by pulse oximetry was less than 97%, the tidal volume was increased to 8.5 mL/kg, and the PEEP increased. No changes were made in ventilator settings between before- and post-tilting measurements. At least 1000 mL of intravenous crystalloid or colloid was infused before the patient was placed in the steep head-down tilt.No premedication was given. Anesthesia was induced with propofol 1.5–2.0 mg/kg, inhaled sevoflurane 3.0% and remifentanil 0.3–0.5 µg/kg/min, and maintained with remifentanil 0.1–0.3 μg/kg/min and inhaled sevoflurane 1.5%. Rocuronium 0.5 mg/kg was used to facilitate orotracheal intubation and was repeated as needed for muscle relaxation. The patients were intubated with a cuffed endotracheal tube and their lungs mechanically ventilated in volume-controlled mode with a mixture of oxygen and air: the fraction of inspired oxygen was 0.4, the tidal volume was 7 mL/kg predicted ideal body weight and positive end-expiratory pressure (PEEP) of 5 cm H® sensor and Vigileo® monitor , central venous blood oxygen saturation (ScvO2) using a PreSep® central venous oximetry catheter (Edwards Lifesciences), and heart rate and regional hemoglobin oxygen saturation (rSO2) using an INVOS™ 5100C cerebral/somatic oximeter . A multiplane TEE probe, iE33® X7-2t transducer  was introduced into the esophagus after induction of anesthesia. The LVEF was calculated in the mid-esophageal four-chamber view, whereas the left ventricular end-diastolic and end-systolic areas were measuring using an iE33 ultrasound system using the modified Simpson’s method (Philips). Urine output was determined by insertion of a urinary catheter during the surgical procedure and a proportion of the urine was included in the total blood loss.Patients’ clinical records were reviewed and relevant patient background information, including age, body mass index and intraoperative variables, were collected. Pre-tilting measurements were performed under stable anesthesia and steady-state conditions with the patients in the horizontal position before surgery began. Post-tilting variables were measured 5 min after the patients had been positioned in a 28° head-down tilt and a pneumoperitoneum of 12–15 mmHg had been achieved. Measured variables comprised left ventricular end-diastolic volume (LVEDV), left ventricular ejection fraction (LVEF) and cardiac index (CI) by transesophageal echocardiography (TEE), blood pressure (BP) in the radial artery, CI using a FloTracPreliminary data for LVEDV recorded in a pilot study of nine patients undergoing RALP were 125.8 ± 25.2 mL (mean ± standard deviation [SD]) before tilting and 116.6 ± 27.4 mL after tilting. The SD was therefore considered to be 25.2 and the expected difference in LVEDV 10 mL. Sample size calculation informed by these data, with an α error level of 5% and an expected pre-and post-tilting difference in LVEDV of 10 mL, found that 60 subjects would be required to obtain an 80% power goal for comparing pre- and post-head down tilt. However, the study was stopped prematurely after 12 subjects had been enrolled as the researchers moved to the different institutes. The pre- and post-tilting measurements obtained were compared using Wilcoxon signed-rank tests, with P < 0.05 considered statistically significant. Data are presented as medians with interquartile ranges. All statistical analyses were performed using GraphPad Prism 6 software .We obtained data from 12 patients. There were no episodes of severe bradycardia. A crystalloid was infused in all cases and an additional 500 mL of colloid was infused in three cases. There were no instances of uncontrollable hemorrhage or respiratory disorder intra- or post-operatively.2  , CI by FloTrac® sensor  or SvcO2 .Relevant patient characteristics and intraoperative variables are shown in Table ® sensor, did not change. These findings indicate that a steep head-down tilt and pneumoperitoneum during RALP did not greatly influence cardiac function in our study patients.We examined changes in circulatory status by measuring hemodynamic and cardiac function brought about by 28° head-down tilting and establishment of the pneumoperitoneum in men undergoing RALP. We found that head-down tilt and pneumoperitoneum significantly decreased LVEF but that LVEDV and CI measured by TEE, and CI measured with a FloTrac® sensing; both these variables reflect stroke volume and heart rate, neither of which changed. Ejection fraction is determined by LVEDV and left ventricular end-systolic volume. Although stroke volume and LVEDV did not change, LVEF decreased in our cohort, suggesting that the decrease in LVEF was not clinically significant. Rosendal et al. reportedly identified no changes in cardiac contractility throughout RALP procedures, although the afterload increased more than twofold [Augmented venous return may result in an increase in right ventricular filling. The high inspiratory pressures required for mechanical ventilation following positioning of a patient in a steep head-down tilt and creation of a pneumoperitoneum reportedly increase right ventricular afterload, reducing right ventricular ejection and consequently increasing right ventricular volumes . A steep twofold , 7. Seve twofold , 6, 8, 9 twofold . Accordi twofold . We did Several authors have recommended fluid restriction during radical prostatectomy to facilitate adequate visualization of the surgical field and minimize blood loss, because this procedure may induce adverse respiratory, cardiovascular, and neurophysiological changes such as severe laryngeal edema, respiratory complications and brachial plexus injury , 11. In A patient with undiagnosed mild mitral valve insufficiency reportedly experienced transitory exacerbation of that insufficiency during RALP . A possi2 increased with head-down tilt, consistent with other studies [2, which did not change. These findings support the conclusion that the effects of steep head-down tilt and pneumoperitoneum on the cerebral circulation are relatively small. Using second-generation near infrared spectroscopy, Kalmar et al. recently reported that cerebral perfusion pressure was maintained above the lower threshold of cerebral autoregulation during RACP, likely because of simultaneous increases in MAP and central venous pressure [In our study, the percutaneous rSO studies , 13. We pressure .®, did not change. These findings indicate that the steep head-down tilt and pneumoperitoneum during RALP did not greatly influence cardiac function in our cohort. Additionally, assessment of CI with TEE did not provide more useful information concerning cardiac function than was provided by FloTrac® in these patients.We found that LVEF decreased after steep head-down tilting and establishment of pneumoperitoneum for RALP, whereas CI and LVEDV measured by TEE, and CI measured by FloTracThe limitations of our trial include its small size, the criteria for patient selection and the use of volume-controlled ventilation during RALP. Different settings for tidal volume and PEEP, or pressure-controlled ventilation, may have produced different results. In our institute, only patients who meet the criteria for ASA I–II undergo RALP. Because a pneumoperitoneum and steep Trendelenburg position are well tolerated by individuals with normal cardiac function, further clinical trials are required to evaluate those with cardiac or valve dysfunction or high pulmonary vascular pressure undergoing this procedure.


E) derived from a traditional cylindrical model, increase significantly with aging. However, the geometric and component changes of aging hearts because of chronic hypertension remain unknown. To better describe the effects, we propose an elliptical elastic and mathematical model to evaluate myocardial stiffness. Ninety-six hypertensive patients (HTNPos)  were enrolled and compared with normotensive controls (HTNNeg) . HTNPos patients had a thicker interventricular septum in diastole (IVSd)  and higher intracardiac pressure , especially the elderly (> 65 years) . Nevertheless, the internal dimension decreased more significantly in the HTNPos rather than in the HTNNeg elderly . We found different directions of cardiac remodeling with normotensive and hypertensive loads. Different from the longitudinal and circumferential strain, E and Poisson’s ratio (υ) are values that directly present the rigidity of myocardium. E was significantly higher in the elderly , whereas υ was significantly higher in all HTNPos patients . Because E and υ reflected the material changes of myocardium in the HTNPos elderly, the proposed elliptical mathematical heart model better describes the geometric deformity induced by aging and hypertension.Hypertensive disorder can cause cardiac deformities. Elastic characteristic parameters, like Young’s modulus of elasticity ( Aging is a major cause of congestive heart failure. More than 75% of patients with congestive heart failure are over 65 , and thePos) and the normotensive group (HTNNeg) to examine the interplay between hypertension and aging on heart geometric deformity. Also, a novel, thick ellipsoidal shell model is introduced and used to estimate the myocardium stiffness and wall thickness of the left ventricle.The effects of hypertensive heart disease on wall thickness and the internal diameter of the common carotid artery have been studied for decades –9, and tPos patients were treated with between 1 and 3 types of antihypertensive medications. This study was approved by the National Cheng Kung University Hospital Institutional Review Board (IRB no: ER-99-111), and each participant signed an informed consent before the medical examination.After excluding participants with poor quality images, LV systolic dysfunction, defined as a left ventricular ejection fraction (LVEF) < 50%, significant structural or valvular heart disease (> moderate severity), we enrolled 96 participants (men: 59.37%), who had undergone echocardiography in National Cheng Kung University Hospital between February 2012 and June 2013. Echocardiographic parameters were based on the recommendations of the American Society of Echocardiography , and medStandard echocardiography was done  with a 3.5-MHz multiphase-array probe. The chamber dimensions and LV mass were measured with the two-dimensionally guided M-mode method, and the LVEF was measured with the two-dimensional (2D) M mode. The intraventricular septal in diastole (IVSd), left ventricular internal dimension end-diastolic (LVIDd), left ventricular posterior wall end-diastolic (LVPWd) and left ventricular internal dimension at end-systolic (LVIDs) internal dimensions were measured sequentially to calculate the geometry and LVEF. Transmitral Doppler blood flow velocity was obtained from an apical four-chamber view, and peak early filling velocity (e), peak atrial velocity (a), and the e/a ratio were recorded. Early diastolic annular velocity (e′) and atrial annular velocity (a′) were also measured to estimate the LV end-diastolic pressure (e/e′). The average of medial and lateral e/e′ was used to represent the estimated intraventricular pressure. To measure the radial, longitudinal and circumferential strains, apical four-chamber views and short-axis views at the papillary muscle level were acquired with frame rates of 70–90 frame/sec and stored for 3 cycles. The method of strain measurement was described previously. In briet test for normally distributed values and a Pearson’s partial coefficient to evaluate correlations. Analysis of variance (ANOVA) tests were 2-sided; significance was set at p < 0.05.SPSS 18.0  was used for all data management and statistical analyses. The study results are mean ± standard deviation (SD). Continuous variables were compared using a Student’s εij = ((1 + υ)/E)σij − (υ/E)δijσkk, where εij and σij are second-order strain tensor and stress tensor, respectively, E is Young’s modulus, υ is Poisson’s ratio, δij is the Kronecker delta, i, j, k ϵ {r, θ, ϕ} denote the spatial indices for radial, circumferential, and longitudinal directions. The strains in the radial, circumferential, and longitudinal directions are shown as follows:A mathematical model for computing the myocardium stiffness and wall thickness of the left ventricle is presented below. The left ventricle is modeled as a thick-walled ellipsoidal pressure vessel  compriseP is acting on the inner surface while the pressure at the outer ventricular surface is negligible, the stresses in the radial, circumferential, and longitudinal directions can be written as wheren=R in Eqs (R0 + T) / 2. Substituting Eqs  is c is cR inting Eqs –(9) intoting Eqs –3) yiel yielR inE and υ) from the above equations, an optimization approach is introduced [To obtain the two quantities (troduced . Define f1(E), f2, and f3 can be assumed as follows:According to Eqs –14), th, th14), Inserting Eqs –18) int int18) iE and υ, respectively, obtains the following equations:Differentiating Setting Eqs  and 21)21) to zeR0, T, and P are acquired from experiments and are as follows:The parametersεrr is the ratio of the radial elongation to the diastolic radius, i.e., εrr = (LVIDd − LVIDs)/LVIDd, εθθ is an average strain for six segments in the circumferential direction, and εϕϕ is an average strain in the longitudinal direction.The quantity Pos group participants  had significantly higher blood pressure than did the HTNNeg group participants (systolic blood pressure (SBP): 129.83 ± 5.63 vs. 150.59 ± 11.76 mmHg; diastolic blood pressure (DBP): 81.19 ± 4.86 vs. 86.44 ± 11.59 mmHg, p = 0.01 and 0.04, respectively). The average ages of the younger and older participants were 50.3 ± 11.2 and 70.7 ± 7.2 years. The mean values of blood glucose, renal function, and lipid profile of the two groups were not significantly different. The incidence of CAD was relatively but nonsignificantly higher in HTNPos participants. Compared with the HTNNeg group, the HTNPos group presented significant thickening of the septum  but not at the posterior wall or LV mass index. Tissue Doppler imaging showed that the mean early diastolic velocity of the mitral annulus was significantly attenuated in the HTNPos group , which corresponded to the higher estimated wedge (e/e′) pressure , especially in the elderly . Conversely, the internal dimension decreased in the HTNPos elderly compared with the HTNNeg elderly . The LV systolic ejection fraction was within the normal range in all participants treated with antihypertensive medications, most of which were calcium channel blockers, angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers (ARBs), and diuretics (primarily for the elders).The HTNNeg and HTNPos groups and found a positive association between IVSd and age both in HTNNeg and in HTNPos participants, but only the correlation in HTNPos participants was significant   . Differewith age . In contwith age . TherefoE, which describes the rigidity of myocardium, rose significantly in the older (70.7 ± 7.2 years) compared with the younger (50.3 ± 11.2 years) participants  . Using either the cylindrical or the elliptical model, we found that, at any given age, E was always higher in HTNPos than in HTNNeg participants  and in the HTNPos group , but the increase in υ was not as great as in E  . Moreoveicipants . Further as in E .E and υ increased with age and were significantly higher in the HTNPos group  and on the intraventricular pressure range (1500–2000 Pa). Grossly HTNE values . The IVSE, along with the increasing e/e′     for the e (e/e′) .E and υ) changed significantly as the heart aged, and (2) the elastic modulus was a better indicator of cardiac remodeling than were LV longitudinal and circumferential strain. Moreover, (3) hypertension independently affected both geometric and elastic remodeling, especially in older hearts. Unlike the aging-induced positive remodeling in the HTNNeg group, the remodeling in the HTNPos group contributes to wall thickening, reduced intracardiac volume, and is called “inward eutrophic remodeling”, which means that it also contributed to luminal narrowing. Finally, (4) compared with prior mathematical simulations [This is the first type of clinical echocardiography based on a mathematical simulation model that describes the geometric and elastic changes in older human hearts under pressure overload. Our most important findings were that (1) the elastic modulus  and global circumferential strain (GCS) showed nonsignificant trends of attenuation with aging. Hypertension was independently but nonsignificantly associated with a further decline of strain, especially in the elderly. In contrast, based on the correlation of e/e′ and wedge pressure,  changes . In the Pos elderly, whereas in the HTNNeg elderly, both the decrease in LV dimension and the thickening of the LV wall were attenuated. Both he mathematical and echocardiographic model reflected these results. Possible reasons for these differences are that (1) compared with Cheng et al. [E and υ values allowed us to more sensitively detect the elasticity changes of the myocardium. Both studies reported that aging alone might be associated with a specific pattern of progressive LV remodeling that is altered by HTN. Consequently, alterations in the typical course of LV remodeling may lead to the development of heart failure in older adults.Cheng et al.  reportedg et al.  our studBy studying the molecular changes and cardiac remodeling in older hearts, researchers have discovered a continuous loss of myocytes surrounded by the adipose and fibrotic tissue deposited in the extracellular matrix in the aging process. In an ax-y plane, εz, and the shear strain γxz and γyz, are assumed to be zero. In other words, deformation in the axial direction (z-direction) is ignored, and deformation in the other two directions is assumed to be independent of the z-direction. In the elliptical model, the strains in the radial, the circumferential, and the longitudinal directions are considered and used to evaluate the changes in LV dimension and myocardial stiffness. In addition, the methods for obtaining the E and υ values are quite different. In the cylindrical model, two linear equations with two unknowns are acquired, and as a result, two quantities can be exactly solved. In the elliptical model, three nonlinear equations with two unknowns, E and υ, are constructed. To obtain the approximate solutions of these two quantities, an optimization method is used [Pos group always has a higher rising rate than the HTNNeg group.In the cylindrical model, the left ventricle is considered an axisymmetric pressurized thick-walled cylinder with a plane strain condition in which the strain normal to the  is used . It is nPos group, the LV expanded not only outward but also inward, resulting in a manifest growth in LV thickness.This is the first study that includes speckle tracking imaging to establish a mathematical model which represents not only the geometric but the elastic changes of aging hearts. Moreover, the interplay between aging and HTN has been well studied using clinical data and then confirmed using a simulation model. Furthermore, unlike other research groups, we found that in the HTNE value was calculated based on the linear correlation between the e/e′ ratio and intraventricular pressure, but some confounding factors, including tachycardia, frame rate, and different angles when sampling, may interfere when measuring e/e′. Third, all HTNPos participants were undergoing medical therapy, which might attenuate the sensitivity of strain in detecting the subtle myocardial changes. Fourth, in our simulation, wall forces, such as bending moments and shears, are ignored due to the symmetry of the chosen configuration, which might not represent the true geometry of the LV. Fifth, MR elastography has emerged as a useful modality for quantitatively imaging the mechanical properties in vivo and has potential to make a unique noninvasive imaging modality for measuring pressure-volume function of the heart. However, its feasibility may be limited in the clinical practice while it could be a validation model for our speckle tracking study[This study has some limitations. First, this was a cross-sectional study, which means the geometrics of the heart cannot be followed longitudinally. The echocardiographic parameters might be affected by the concomitant hemodynamic image acquisition. Also, the ing study.Finally,This is the first study to use a mathematical model to determine and describe the geometric and elastic changes in the aging human heart under a blood pressure overload. The vulnerability of the elderly to higher blood pressure may contribute to their heart failure. Therefore, combined with our simulation model, additional studies that focus on the molecular pathways ought to shed light on the key mediators. In addition, our model also helps improve the evaluation of the cardiac response to different drugs, which might lead to new therapeutic strategies, to understanding the changes in myocardial stiffness with aging, and to detecting occult diastolic dysfunction in the early stage of chronic systemic diseases like HTN and diabetes mellitus.S1 FigE) in HTNNeg and HTNPos participants in older (70.7 ± 7.2 years) and younger (50.3 ± 11.2 years) participants.(A) Dimensional (IVSd) and (B) elastic changes ((TIF)Click here for additional data file.


Right ventricular (RV) function appears to declines following cardiac surgery, particularly long axis function. Three principal speculated causes are suggested: a) loss of constraint when pericardium is opened, b) intra-operative ischemia, c) post-operative tethering. The relative contributions are unknown. Similarly, the impact on different aspects of RV function  is obscure.The length and complexity of cardiac operations is also thought to contribute to RV impairment. We sought to untangle these relative contributions by comparing pre- and post-surgery RV function changes in a cohort of patients where all had aortic valve replacement (AVR) but 1/3 had in addition grafting (CABG). Different measures of RV function were used and paired pre and post.Eighty-one patients were scanned at 1.5T (Siemens Avanto) prior to, and 1 year following AVR (n = 59) or combined AVR and CABG (n = 22), with full pericardial opening. RV volumes and function were calculated using standard techniques. RV longitudinal function was assessed using different measures, Figure A - Tricuspid annular displacement - the distance measured between tricuspid annulus in diastole and systoleout - the difference in the distance between tricuspid annulus and a fixed point on anterior chest wall in diastole and systoleB - TAPSEC - RV apical motion - the difference in the distance between the RV apex and a fixed point on the anterior chest wall in systole and diastole.in - the difference in the distance between tricuspid annulus and RV apex in diastole and systole D- TAPSERV volumes and ejection fraction were within normal limits for all subjects, pre and post, with no significant reductions in RV function and volumes, Table out declined after surgery by 41% (p < 0.0001) and 43% (p < 0.0001), respectively. Apical motion increased post operatively by 52% (p < 0.0001), meaning that overall TAPSEin only fell by 21% (p < 0.0001), Figure RV longitudinal function however assessed using tricuspid annular displacement and TAPSEp < 0.01). Using tricuspid annular displacement <16 mm alone, 68 out of 81 patients (84%) would be classified as having impaired RV function post-operatively, despite preserved RVEF.RVEF had weak correlation with each of the markers of RV longitudinal function,  respectively.There were no significant differences between the AVR+CABG and AVR alone groups in any of the measures of RV function (RVEF: 65 ± 9% versus 64% ± 9%, The effect of cardiac surgery on overall RV function is overstated - yes, tricuspid annular displacement falls, but apical basal contraction increased in compensation.Doing additional grafts has no detectable incremental detrimental effect on RV function.Ischemia does not appear a likely cause of changes - tethering and/or loss of pericardial constraint appear to be the principal mechanisms of RV changes.


Prior myocardial infarction (MI) is associated with increased mortality and is prevalent in certain high risk patient groups. Electrocardiogram may be used in diagnosis, however, sensitivity is limited, thus non-invasive imaging techniques may improve diagnosis. We investigated whether global longitudinal strain (GLS) and longitudinal strain parameters are reduced in patients with prior MI but preserved left ventricular ejection fraction (LVEF). The study included 40 clinical patients with prior MI occurring >3 months previously  with LVEF ≥ 55% and 40 controls matched for age and LVEF. GLS, global longitudinal strain rate (GLSR) and early diastolic longitudinal strain rate (GLSRe) were measured from cine imaging feature tracking analysis. Presence of wall motion abnormality (WMA) and minimum systolic wall thickening (SWT) were calculated from cine imaging. GLS was −17.3 ± 3.7% in prior MI versus −19.3 ± 1.9% in controls (p = 0.012). GLSR was −88.0 ± 33.7%/s in prior MI versus −103.3 ± 26.5%/s in controls (p = 0.005). GLSRe was 76.4 ± 28.4%/s in prior MI versus 95.5 ± 26.0%/s in controls (p = 0.001). GLS accurately identified prior MI [AUC 0.662 (95% CI 0.54–0.785) p = 0.012] whereas WMA [AUC 0.500 (95% CI 0.386–0.614) p = 1.0] and minimum SWT [AUC 0.609 (95% CI 0.483–0.735) p = 0.093] did not. GLS, GLSR and GLSRe are reduced in prior MI with preserved LVEF. Normal LVEF and lack of WMA cannot exclude prior MI. Prior MI should be considered when reduced GLS, GLSR or GLSRe are detected by non-invasive imaging. Prior myocardial infarction (MI) is defined as either the presence of pathological Q waves on an electrocardiogram (ECG), regional loss of myocardium on cardiovascular (CV) imaging in the absence of a non-ischemic cause or pathological findings supportive of prior MI . MyocardThe presence of unrecognized MI detected by LGE is associated with a tenfold increase in risk of CV mortality, which appears to be incremental to conventional clinical and imaging risk factors . RecogniLongitudinal strain parameters theoretically have the potential to detect prior MI. Myocardial fibers situated in the left ventricular (LV) subendocardium contribute significantly to longitudinal LV contraction in systole . These fGLS has been demonstrated to be reduced in patients with heart failure with reduced ejection fraction (HF-REF) due to chronic ischemic heart disease  and in tWe hypothesized that patients with prior MI detected by LGE but preserved LVEF would have impaired GLS and longitudinal strain rates compared to matched normal controls.This was a single centre case control study involving 40 clinical patients with prior MI occurring >3 months previously and preserved LVEF (≥55%) and 40 controls matched for age and sex with LVEF (≥55%). Prior MI patients were retrospectively recruited from consecutive patients undergoing CMR for clinical reasons and selecting those with MI and preserved LVEF. Healthy controls were prospectively recruited volunteers with no history of cardiac disease. All participants were screened for CV risk factors by completion of a health questionnaire and from medical records.Patients with significant arrhythmia (defined as uncontrolled tachycardia >100 bpm at the time of CMR study) were excluded. Prior MI patients with a history of acute MI or chest pain within the preceding 3 months were excluded on the basis that significant alterations to both myocardial scar burden and LV systolic function could have occurred in this time frame. Controls had no known history of CV disease.All patients underwent CMR at either 1.5 T (Philips Ingenia) or 3.0 T (Philips Achieva) and controls at 3.0 T (Philips Achieva). Images were acquired with breath holding on end-expiration prior to contrast administration and prospectively gated using a 3-lead vector ECG.Cine images were planned from the scout images and for every patient a 2 chamber (2Ch), 4 chamber (4Ch) and an LV short axis cine stack were acquired to ensure full coverage of the left ventricle. Typical image acquisition parameters for SSFP cine acquisitions were as follows: TR 2.6 ms, TE 1.3 ms, flip angle 40°, field of view 320 × 340 mm × 100 mm, voxel size 2 × 1.62 × 10 mm, 30 cardiac phases.LGE imaging was performed in all patients with acquisitions of a short axis LV stack, 2Ch and 4Ch obtained 10 min after administration of 0.2 mmol/kg Gadolinium DTPA contrast  using inversion recovery-prepared T1 weighted echo. The optimal inversion time (TI) to null normal myocardial signal ascertained by the Look Locker approach. Between 10 and 12 short axis LV, 2Ch and 4Ch images were acquired for every patient. Further imaging with altered phase-encoding direction or systolic imaging were acquired when prior MI was suspected after initial imaging.All post processing analysis of CMR scans was performed using the same software . LV contours were drawn manually at both end diastole and end systole on the LV short axis SSFP cine stack. LV papillary muscles were considered part of the LV cavity.Percentage myocardial systolic wall thickening (SWT) was calculated from the end diastolic and end systolic contours as previously reported . SWT wasThe presence of LGE in a subendocardial pattern suggestive of prior MI was determined independently by two physicians with over 4 years’ experience in CMR. Quantitative assessment of myocardial scar burden was performed using a threshold of 50% of the maximum intensity within the scar  which has been proposed as the most reproducible method for this purpose . After oThe strain parameters GLS, GLSR and GLSRe were calculated using feature tracking software from 4Ch and 2Ch SSFP cine acquisitions Fig. . Prior tt test and Mann–Whitney U test were used as appropriate to compare continuous variables. Cut-off values to identify prior MI were derived from receiver-operating characteristic (ROC) curve analysis using Youden index giving maximum sensitivity and specificity. AUCs were compared by using validated methods described by DeLong et al. .AUC for the ability of each longitudinal strain parameter to correctly identify prior MI were as follows Fig. : GLS 0.6Scar quantitation was successfully performed in all prior MI patients. The range of absolute scar mass was wide at between 0.7 and 21.4 g. The overall mean absolute scar mass was 5.5 ± 4.3 g, equating to a relative percentage of LV mass of 4.9 ± 3.3%.Two approaches were used in determining sensitivity and specificity for the correct identification of prior MI by the different longitudinal strain values assessed. Firstly, the cut-off value giving maximum area under the curve was determined for each variable. Secondly, the value giving maximum specificity was determined. Results are summarized in Table Variables including patient demographics, risk factors for CVD and presence of prior MI were analyzed to determine univariable predictors of GLS Table . MultivaOn intraobserver analysis, mean GLS values by CMR feature tracking were similar at −20.3 and −19.6% (p = 0.60) and CoV 3.9%. On interobserver analysis, mean GLS values CMR feature tracking were again similar at −20.3% and −19.6 (p = 0.62) and CoV% 4.0%.We have found that in patients with preserved LVEF and prior MI there is impairment of GLS, GLSR and GLSRe. Furthermore, impairment of GLSR and GLSRe had superior diagnostic accuracy than the quantitative assessment of WMA in the detection of prior MI. These results demonstrate that prior MI may be detected when GLS is impaired when LVEF is preserved, although its ability to detect prior MI in this context is moderate.Impairment of longitudinal measures of strain in prior MI may relate to myocardial fiber arrangement within the left ventricle. Subendocardial myofibers contribute predominantly to contraction in the longitudinal plane with subepicardial fibers providing a lesser contribution. Conversely, both circumferential and radial motion of the myocardium are generated by fibers predominantly located in the midwall . LongituThere was no significant difference in the proportion of patients with WMA (>30% minimum SWT in any LV segments) between the prior MI and control groups. Our finding of WMA in asymptomatic controls was not unexpected and has previously been reported elsewhere in the literature , 22.The importance of LVEF and regional LV systolic function as indicators of prior MI is stressed in international guidelines . Our resOf the longitudinal strain parameters assessed, GLS was moderately useful in terms of specificity and sensitivity with a cut-off value of ≥18% giving a sensitivity of 60% and specificity of 72.5% and was the most useful of the 3 strain values assessed. These findings broadly correlate with those of Nucifora et al. who demonstrated a correlation between reduced GLS measured by echocardiography and the presence of significant coronary artery disease on CT coronary angiography in patients with symptoms suggestive of stable angina with normal LVEF . In thatGLS has good inter and intra-observer variability when measured by CMR feature tracking as demonstrated in both this and another study . SimilarSeveral studies have demonstrated impairment of GLS, predominantly by speckle tracking echocardiography, in a range of disease states including diabetes , heart fOur findings support the potential utility of GLS as a screening tool for identifying prior MI in patients with preserved LV ejection fraction, although when used alone, its ability to correctly identify prior MI in this context is only moderate. Further prospective studies are needed to identify whether combining it with other imaging and/or clinical parameters lead to improvement in its specificity and sensitivity. As GLS has been shown to be impaired independently of LVEF in aortic stenosis , hypertrThe values for the strain parameters measured in this study were calculated using feature tracking post-processing software. This remains a research application and currently lacks the clinical validation to enable its adoption into routine clinical practice. Nevertheless, both GLS and GLSR can be readily measured using modern echocardiographic speckle tracking  which haCMR tagging has traditionally been considered the reference standard technique for calculation of strain values and was not used in this study. We have elected to use feature tracking preferentially for this study because tagging techniques suffer from both lower temporal resolution and fading of the tag overlay as the cardiac cycle progresses . FurtherWe have not carried out invasive assessment of coronary anatomy in all patients and it is possible that undiagnosed ischaemia may have contributed to impairment of longitudinal strain parameters. However, performing coronary angiography on patients in whom it is not clinically indicated would not be ethically appropriate.Finally, there were higher rates of CV risk factors in our prior MI population compared with healthy volunteers, thus it is unclear as to their relative contribution (if any) to the observed decrease in GLS seen in prior MI patients. Nevertherless, in our multivariable analysis, only prior MI was an independent predictor of change in GLS and CV risk factors including hypertension, smoking, hypercholesterolemia and diabetes were not.The strain parameters GLS, GLSR and GLSRe are reduced in patients with prior MI in the context of normal LVEF. A normal LVEF and lack of WMA is insufficient to exclude prior MI. Prior MI may be suspected when impaired GLS, GLSR or GLSRe are detected by non-invasive imaging.


We review the trials that have demonstrated potentially harmful effects from right ventricular (RV) apical pacing as well as reviewing the evidence of alternative RV pacing sites and cardiac resynchronization therapy (CRT) for patients who have heart failure and atrioventricular (AV) block.The role of CRT in patients with AV block and impaired left ventricular function remains an important consideration. The BLOCK HF trial demonstrated better outcomes with CRT pacing over RV pacing in patients with left ventricular systolic dysfunction (LVSD) and AV block who were expected to have a high RV pacing burden, but failed to demonstrate a mortality benefit.CRT seems to have a beneficial effect on left ventricular reverse remodeling, systolic function, and clinical outcomes in patients with New York Heart Association (NYHA) functional class I–III heart failure, moderate to severe LVSD, and AV block compared to RV pacing. However, it is less clear whether there is a similar benefit from CRT in patients with a high percentage of RV pacing who have normal or mild LVSD in the treatment of AV block. Right ventricular (RV) pacing is an important and effective treatment in patients with atrioventricular (AV) block. RV pacing restores the heart rate to a pre-determined rate; however, a high RV apical pacing percentage/burden may promote left ventricular systolic dysfunction (LVSD) –9. AlterSingle- or dual-chamber RV pacing is the mainstay of treatment for symptomatic AV block. However, there is increasing evidence of potential adverse effects with chronic RV apical pacing secondary to mechanical and electrical dyssynchrony , 17. TheSeveral clinical studies have established the potential adverse effects of chronic RV pacing on LV function. The exact pathophysiological process underpinning the deleterious effects from chronic RV pacing is not clear. RV apical pacing may have adverse effects on hemodynamics, remodeling, mechanical function, myocardial metabolism, and perfusion due to mechanical and electrical dyssynchrony , 27, 28.n = 120) or right ventricular high septum (RVHS) (n = 120). At 2 years, LVEF decreased in both the RV apex  and the RVHS groups   [P = 0.001] and fewer hospitalizations for heart failure   . Fewer p= 0.013] . There w= 0.013] . The Lef= 0.013] . Patient = 0.04) . At 6 mo = 0.03) . The LVE = 0.03) . The aut = 0.03) .BLOCK HF was a landmark US-based trial that revealed encouraging evidence that improved outcomes may be achieved with CRT pacing compared to RV apical pacing in patients with LVSD and AV block when a high percentage of RV pacing is anticipated , 15. As The role of CRT pacing in patients with AV block and impaired LV systolic function remains an important consideration. The BLOCK HF trial demonstrated better outcomes with CRT pacing over RV pacing in patients with LVSD and AV block in patients expected to have a high RV pacing burden. However, BLOCK HF failed to demonstrate any mortality benefit. The preliminary results of the European-based BioPace trial have not confirmed the same statistically significant benefit, although we are still awaiting the full results to be published. In the interim, CRT pacing seems to have a beneficial effect on LV reverse remodeling, systolic function, and clinical outcomes in patients with NYHA functional class I–III heart failure, moderate to severe LVSD, and AV block compared to RV pacing. However, it is less clear whether there is a similar benefit from CRT in patients with a high percentage of RV pacing who have normal or mild LVSD in the treatment of AV block.


Danio rerio) is an increasingly popular model organism in cardiovascular research. Major insights into cardiac developmental processes have been gained by studies of embryonic zebrafish. However, the utility of zebrafish for modeling adult-onset heart disease has been limited by a lack of robust methods for in vivo evaluation of cardiac function. We established a physiological protocol for underwater zebrafish echocardiography using high frequency ultrasound, and evaluated its reliability in detecting altered cardiac function in two disease models. Serial assessment of cardiac function was performed in wild-type zebrafish aged 3 to 12 months and the effects of anesthetic agents, age, sex and background strain were evaluated. There was a varying extent of bradycardia and ventricular contractile impairment with different anesthetic drugs and doses, with tricaine 0.75 mmol l−1 having a relatively more favorable profile. When compared with males, female fish were larger and had more measurement variability. Although age-related increments in ventricular chamber size were greater in females than males, there were no sex differences when data were normalized to body size. Systolic ventricular function was similar in both sexes at all time points, but differences in diastolic function were evident from 6 months onwards. Wild-type fish of both sexes showed a reliance on atrial contraction for ventricular diastolic filling. Echocardiographic evaluation of adult zebrafish with diphtheria toxin-induced myocarditis or anemia-induced volume overload accurately identified ventricular dilation and altered contraction, with suites of B-mode, ventricular strain, pulsed-wave Doppler and tissue Doppler indices showing concordant changes indicative of myocardial hypocontractility or hypercontractility, respectively. Repeatability, intra-observer and inter-observer correlations for echocardiographic measurements were high. We demonstrate that high frequency echocardiography allows reliable in vivo cardiac assessment in adult zebrafish and make recommendations for optimizing data acquisition and analysis. This enabling technology reveals new insights into zebrafish cardiac physiology and provides an imaging platform for zebrafish-based translational research.The zebrafish ( Summary: Standardization of zebrafish echocardiography provides insights into cardiac physiology in normal and diseased states, with application for functional studies in zebrafish models of heart disease. Danio rerio) is an increasingly popular vertebrate model organism for research studies into human diseases because of their low maintenance costs, high fecundity, fast generation times and ease of genetic manipulation    have disin vivo assessment of cardiac function in adult zebrafish.The aim of our study was to develop, optimize and validate a protocol for underwater zebrafish echocardiography under conditions as close as possible to the normal physiological state. We employed reverse translation of echocardiographic principles used in clinical practice, and have adapted these for use in a small aquatic organism. Here, we show that high-resolution imaging of adult zebrafish hearts is feasible and can provide detailed quantitative assessment of ventricular size and function. We evaluated indices of ventricular systolic and diastolic performance, and determined the effects on these parameters of anesthetic agent, age, sex, and background strain. To investigate whether echocardiography is sufficiently sensitive to detect disease-associated changes in myocardial contraction, we used two models of adult cardiac dysfunction: (1) a hypocontractile model caused by diphtheria toxin A (DTA)-induced myocarditis , and (2)The heart was adequately visualized in all fish with high image quality (see Movie 1). In zebrafish, the heart is located in the ventral midline, immediately caudal to the level of the gills. The apex of the heart is directed ventrocaudally. The atrium is located dorsal to the ventricle in the LAX view, whereas the bulbus arteriosus is situated dorsocranial to the ventricle  A-C and sentricle C.Movie 2).Reproducible sections of the ventricle were more reliably obtained in the LAX view than in the SAX view. Consequently, B-mode images and speckle tracking in the LAX view were used to derive measurements of ventricular chamber size and function. In human heart development, there is progressive compaction of the trabeculated ventricular myocardium. Consequently, the blood–endocardial border is clearly seen and is used in clinical echocardiography to demarcate the ventricular chamber cavity. Residual trabeculation, valve leaflets and chords are included as part of the chamber cavity and not the ventricular wall for echocardiographic measurements . In contθ  and the highest measured velocity best approximates the true velocity. In the SAX view, the atrioventricular annulus was clearly discerned (Movie 3), allowing more accurate assessment of tissue Doppler indices than in the LAX view.Color Doppler and pulsed-wave Doppler were used for the hemodynamic assessment of ventricular inflow from the atrium during diastole G,J, as wiscerned E, and mon=10 each group) and observed heart rate responses prior to echocardiographic imaging (Table S2). Using tricaine 1.5 mmol l−1, heart rates were (mean±s.d.) 72±15 bpm, 72±12 bpm, 71±10 bpm, and 63±10 bpm at 1, 3, 6 and 9 min after induction of anesthesia. Reducing the dose of tricaine to 0.75 mmol l−1 resulted in higher heart rates, particularly during the first 6 min: 125±10 bpm, 122±10 bpm, 106±11 bpm, 96±8 bpm, respectively; P<0.001 for all time-points versus tricaine 1.5 mmol l−1. With 2-PE 0.0036 mmol l−1, heart rates were higher than with tricaine 1.5 mmol l−1 (P<0.001) but lower than tricaine 0.75 mmol l−1 (P<0.001): 89±13 bpm, 90±14 bpm, 83±13 bpm, and 72±16 bpm at 1, 3, 6 and 9 min after anesthesia induction (Table S2). Adequate sedation for echocardiographic imaging was achieved with tricaine 0.75 mmol l−1 and with 2-PE 0.0036 mmol l−1. Lower doses of these agents resulted in inadequate or inconsistent levels of sedation and were not evaluated further.Resting heart rates in adult zebrafish have been estimated to be 120-130 beats per min at 28°C . Since m−1 and 2-PE 0.0036 mmol l−1 at any time point  between tricaine 0.75 mmol lme point B, howevend 9 min C. Beyond−1 showed the most favorable anesthetic profile, with higher heart rate and fewer cardio-depressant effects than the other drug and dose combinations tested. Given these findings, and the fact that the cardiac sonographer was able to complete all measurements within 3 min of anesthesia induction, we selected tricaine 0.75 mmol l−1 for all subsequent studies.In summary, tricaine 0.75 mmol ln=10 each group) underwent serial echocardiography at 3, 6, 9, and 12 months (Table S3). There were no significant differences in heart rate between anesthetized males and females  and there were no significant differences between males and females. Temporal and sex differences were found, however, in diastolic function. The peak early diastolic (E) wave velocity changed with age in in males (P<0.001) and females (P=0.001). E wave velocity was similar in both sexes at 3 months, but declined from 6 months onwards, with greater reductions seen in females (P<0.001 for both sexes), which were more pronounced in females (P<0.001), with relatively lower ratios in females at 6, 9 and 12 months (P=0.03), á (P=0.01), and ś (P<0.001) wave velocities with increasing age. There were no statistically significant changes in é wave and á wave velocity over time in males, but the ś wave velocity decreased with age (P<0.001).Male and female wild-type fish , end-systolic longitudinal diameter (ESDLONG), end-diastolic basal diameter (EDDBASE), end-systolic basal diameter (ESDBASE)], two-dimensional , and three-dimensional  parameters in wild-type zebrafish. The one-dimensional parameters, particularly EDDLONG and ESDLONG, consistently had the smallest coefficients of variation, while EDV and ESV had the greatest variability (Table S4).In clinical cardiology, ventricular chamber size is typically estimated using orthogonal diameters or derived volumes, measured at both end-diastole and end-systole. In zebrafish echocardiographic studies reported to date, ventricular size has mainly been assessed using volume, and to a lesser extent, diameter and area . To evalP<0.001). When compared with males, female fish were significantly heavier (Table S4).The substantial variability in EDV and ESV could result from the fact that ventricular volumes are not directly measured, but derived from one-dimensional and two-dimensional data. We also considered the possibility that body size might be a confounding factor and that normalization of volumes might be required. Corresponding with normal growth, weight and body length (snout to base of tail fin) increased in all fish from 3 to 12 months of age . Ventricular areas and volumes were similar in male and female fish at 3 months, but were higher in females at 6, 9 and 12 months (Table S4).For males and females, ventricular chamber diameters significantly increased with increasing age (Table S5). With regard to sex differences, we found that indexing to weight, BMI and BSA abolished differences in EDV between male and female fish of the same age, whereas indexing to length did not. With regard to fish of different ages, EDV differences were no longer significant after indexing for BSA and weight, but remained significant for BMI and length. For EDV (and VAd), normalization to BSA and weight consistently reduced the coefficient of variation compared with that for non-standardized values, especially in male animals. Normalization did not have any noticeable effect on the coefficient of variation for the one-dimensional parameters (e.g. EDDLONG) but these still had the smallest coefficients of variation irrespective of normalization.We indexed EDV to weight B, lengthn=10-13) from four separate wild-type strains  are reported in P<0.001 for all comparisons). Ventricular EDV differed between wild-type strains (P<0.001), even after normalization to BSA (P=0.007). Although EF was similar (P=0.15), the results for global longitudinal strain (GLS) suggest that there might be subtle inter-strain differences in baseline systolic function. There were significant differences in pulsed wave Doppler and tissue Doppler indices indicating likely inter-strain effects on diastolic function.Characteristics of 9-month-old male fish (n=8) before and 7 days after induction of DTA by 4-hydroxy-tamoxifen (4-HT) . The 4-HT-treated fish typically developed a ventral protrusion (P=0.001), consistent with edema resulting from cardiomyocyte cell death, which is frequently observed echocardiographically in humans affected by acute fulminant myocarditis (P<0.001) and the extent of cardiomyocyte loss .To determine whether pathological myocardial contractile impairment could be effectively identified by echocardiography, we evaluated cardiac function in male wild-type fish  at baseline and after an 18-day period of PHZ administration every second day . PHZ-treated fish showed generalized pallor, which was also observed in the explanted hearts . In general, there was more variability in the post-treatment measurements than in baseline data, reflecting not only intrinsic differences between animals but also differential responses to treatment.Movie 2). Global and peak values for longitudinal strain, strain rate and displacement had less variability than individual segment values . Consistent with our observation that the epicardium in zebrafish does not undergo the same degree of displacement as the endocardium during the cardiac cycle, estimation of FAC using the inner border of the compact myocardium detected larger changes in systolic function than epicardial FAC, with a greater net change and statistical significance in both disease models (Table S6).For the derived systolic parameters, the best indices with respect to high net change and small variability were EF and FAC D. In eacFor diastolic parameters, higher velocity signals tended to show less variability than low velocity signals, with the peak A wave velocity showing the highest net change and lowest variability across both models E. As forTable S9).To determine intra-observer variability and repeatability of echocardiographic measurements, 10 male wild-type fish were scanned twice, at a 5-day interval, with image acquisition and data analysis undertaken by a single observer. When the first set of images was analyzed twice by the same observer, the mean difference in EF was −0.02% (95% CI −2.4 to 2.4%) with an intra-class correlation coefficient for single measures of 0.92 (95% CI 0.82 to 0.97). The average measures intra-class correlation coefficient was 0.96 (95% CI 0.90 to 0.98), suggesting that there was high reproducibility in mean EF measured by the same operator in the same population. For two-dimensional area measurements, short axis length, pulsed-wave Doppler and tissue Doppler indices, the intra-class correlation coefficients were very high (0.98 to 1.00) (Table S9).When the first and second set of images were both analyzed by the same observer, the mean difference in EF between two measurements was −0.02% (95% CI −3.3 to 3.3%), with an intra-class correlation coefficient for single measures of 0.90 (95% CI 0.77 to 0.96). The average measures intra-class correlation coefficient was 0.95 (95% CI 0.87 to 0.98), suggesting that there was relatively high reproducibility in mean EF measured in the same population on different days. For other parameters, the agreement between the two sets of measurements was very high with intra-class correlation coefficients ranging from 0.97 to 0.99 (Table S9). Thus, although inter-observer variability was greater than intra-observer variability for individual measurements, there remained moderately high reproducibility in the mean population measurements.To evaluate inter-observer variability, the first set of echocardiographic images was analyzed by two independent observers. Reproducibility for EF was moderate . For other parameters, the inter-class correlation coefficients remained moderately high, particularly with regards to the average measures inter-class correlation coefficient (Table S10). For s.d. of 5%, experimental models expecting large changes in EF require few fish to achieve sufficient power. However, study groups of ≥10 fish per investigation arm are required to detect absolute changes in EF of ∼5% in a paired study design and ≥17 fish per investigation arm in an unpaired design. Experiments expecting higher s.d, or smaller differences in mean EF would require substantially greater numbers of fish per investigation arm for adequate power.Animal and operator variability and intervention effect size directly influence the sample size needed to sufficiently power studies to reliably detect statistically significant differences when present. To estimate the numbers of fish required for zebrafish echocardiographic studies, we undertook power calculations based on data from our group and others for standard deviations in EF in wild-type fish . We observed progressive bradycardia and reduced EF with both agents over a range of doses and found that tricaine 0.75 mmol l−1 gave the most favorable profile while at the same time providing adequate anesthesia and respiration. Given the marked decline in functional parameters after 6 min of anesthesia, information obtained after this time is unreliable and image acquisition should ideally be completed within 3 min. Fish that are physiologically compromised as a result of disease (e.g. heart failure) display a significant time-dependent decrement in heart rate and are likely to be more susceptible to the cardio-depressant effects of anesthesia , and highest with three-dimensional parameters (e.g. EDV and ESV). The variability in ventricular volumes was maximal in zebrafish at the extremes of the ages we studied, and might be explained in young fish by problems of finite resolution when imaging small ventricles, and in older fish by variations in body size. The more modest variability in volumes seen at 6-9 months suggests that this might be an ideal age range for undertaking adult zebrafish studies. Given these variability considerations, ventricular size seemed to be best assessed by measurement of linear diameters, especially EDDLONG and ESDLONG. However, EDV and ESV need to be determined as these are required for calculation of EF. It is useful to provide these complementary types of measurements, as any changes in ventricular size would be more confidently identified by concordant trends in these data. To account for individual body habitus, indexation of ventricular size is common practice in clinical echocardiography  or linear dimensions (for FS). Averaging data obtained from multiple heart beats helped to account for cardiac cycle variation, and also reduced the within-animal physiological variation. Care was taken to exclude cardiac cycles affected by significant motion artefact. GLS has been shown to predict adverse cardiovascular outcome in cardiac disease  and mighThe high resolution permitted by the high-frequency transducer, the excellent conducting properties of water, and proximity of the zebrafish heart to the transducer allow remarkable clarity of the pulsed-wave Doppler and tissue Doppler signals, permitting an unprecedented opportunity to study diastolic ventricular function in adult zebrafish. Evaluation of diastolic properties is a key component of human cardiac function assessment, particularly in disease states in which diastolic defects precede systolic dysfunction, yet this has generally been lacking from zebrafish cardiac studies. We compared different imaging planes and found that pulsed-wave Doppler and tissue Doppler signals were best recorded in the SAX view, where the atrioventricular annulus was clearly seen and the angle between the velocity of motion and the beam of the ultrasound was minimized.Movie 5), suggesting that atrial contraction was the principal driver of cardiac output. Given this reliance on atrial contraction for ventricular filling, it can be predicted that atrial contractile impairment, for example, as a result of atrial dysrhythmias, would have profound hemodynamic, and potentially fatal, consequences in zebrafish.In the normal zebrafish heart, the A wave velocity was characteristically higher than the E wave, indicating that ventricular filling predominantly occurs during atrial systole. This was reflected by low E/A ratios, ranging from 0.2-0.3 in adolescent fish, down to 0.06 in adult fish, and is in marked contrast with humans, where the E/A ratio is typically ≥1.0 in healthy young adults . We noteAlthough high frequency echocardiography represents a major advance in assessing cardiac function, assessment of cardiac structure remains challenging. In particular, the irregular shape of the zebrafish atrium complicates evaluation of chamber size and precludes the potential application of geometric models for volume estimation. Three-dimensional imaging modalities such as micro-computed tomography and optical projection tomography might facilitate cardiac structural characterization and warrant further evaluation. As for rodent echocardiography, operator expertise is a significant variable and optimal results can only be obtained when image acquisition and data analysis are undertaken by trained experienced personnel.In conclusion, our findings show that high-frequency echocardiography is a powerful tool for non-invasive serial assessment of cardiac function in adult zebrafish. Techniques used in human echocardiography such as pulsed-wave Doppler, tissue Doppler, speckle-based deformation imaging, and ventricular strain can now be reliably used to obtain functional data from zebrafish as young as 3 months of age. Understanding the importance of biological and technical variability, and employing techniques aimed at reducing their impact, will be crucial to future study design. This enabling technology opens up new avenues of investigation that can take advantage of zebrafish models to study cardiac regeneration as well as mechanisms, treatment and prevention of adult-onset human heart disease.TE background were evaluated (unless specified otherwise).Zebrafish were maintained according to standard procedures . All exp−1  to induce sedation without cessation of breathing. Anesthetized fish were transferred into a scanning chamber containing system water with the same concentration of anesthetic. The scanning chamber consisted of a glass beaker containing a weighted sponge with a groove cut into it, which served as a support for the fish while it was undergoing scanning. The fish was positioned on the sponge ventral side up, covered by ∼10 mm of water. The ultrasound transducer was then lowered gently into the water over the fish with 3 mm clearance of the body  equipped with a high frequency transducer . Echocardiographic images were obtained in two planes: LAX ×30 µm . B-mode imaging quality was further optimized by adjusting focal depth, gain, image width and depth. Color Doppler and pulsed-wave Doppler were used for the hemodynamic assessment of ventricular inflow from the atrium during diastole  with the operator blinded to treatment group. Heart rate was measured from B-mode image sequences by sampling the number of heart beats in a 15 s window. For ventricular measurements, at least three representative cardiac cycles were averaged. Given that examined wild-type zebrafish showed physiological cardiac cycle variation, special care was taken to ensure that beats occurring during significant irregularity of cardiac cycle length, and also beats affected by motion artefacts, were excluded from analysis.BASE and ESDBASE were obtained by measuring the distance between the inner border of the compact myocardium at the base of the ventricle at end-diastole and end-systole, respectively /EDDLONG; FAC=(VAd–VAs)/VAd.Ventricular chamber dimensions were obtained from B-mode images in the LAX view. EDDectively . The cor0): ε=L–L0/L0. Ventricular myocardial strain, displacement, strain rate, and velocity were recorded as individual values , global values , or peak values .Speckle-tracking analysis of ventricular wall motion was performed with the VevoStrain™ analysis software package  and was used to assess ventricular volumes and EF. For this analysis, the inner border of the compact myocardium was used to define the internal chamber. EF=(EDV–ESV)/EDV; cardiac output=heart rate×stroke volume (SV), with SV=EDV–ESV. The speckle-tracking software was also used to calculate ventricular wall strain (ε), defined as the change in the length (L) of a deformed object divided by the original length  , BMI [calculated as BMI=weight/(length)brafish) .For assessment of diastolic function, we examined the following pulsed-wave Doppler signals: E wave – peak velocity of blood inflow across the atrioventricular valve during early diastole; A wave, peak velocity of blood inflow across the atrioventricular valve during atrial systole. Tissue Doppler signals obtained were: é – tissue velocity at the atrioventricular annulus during early diastole; á – tissue velocity at the atrioventricular annulus during atrial systole; ś – tissue velocity of the atrioventricular annulus during ventricular systole.−1 (0.04%) or 0.75 mmol l−1 (0.02%)  or 2-PE, 0.0036 mmol l−1 (1:2000 dilution) or 0.0024 mmol l−1 . Fish were immersed in anesthetic solution for 30-45 s before transfer to the scanning chamber. Heart rate and ventricular functional indices were estimated at 1, 3, 6 and 9 min after first exposure to anesthetic solution.Male wild-type fish (6 months old) were anesthetized using tricaine mesylate 1.5 mmol ln=10-13) from four separate wild-type strains , each aged 9 months. Studies were performed using the same protocol and environmental conditions.Body size, heart rate, ventricular dimensions and cardiac function were compared in male fish  line  was used to induce acute toxic cardiomyopathy, as described (Cre recombinase in the presence of 4-HT (Sigma-Aldrich) induces DTA expression, resulting in marked cardiomyocyte death peaking at 7 days post-exposure. Male wild-type fish (aged 6 months) were exposed to 1.5 µM 4-HT dissolved in 100% ethanol for 12 h. Cardiac function was compared in individual fish by echocardiography before and 7 days after treatment. Following echocardiography, fish were then euthanized and their hearts explanted for morphological assessment and histology. The extent of viable heart tissue was quantified by determining the ratio of tissue expressing mCherry (viable cardiomyocytes without DTA expression) to the amount of tissue in the entire ventricle. Areas of the image that did not appear fluorescent red were considered to represent dead tissue (https://imagej.nih.gov/ij/).The escribed . In thisd tissue . All imaPHZ (Sigma-Aldrich) was used to induce chronic hemolytic anemia and volume overload-related cardiac remodeling in zebrafish . Male wit-tests were used to determine differences between fish populations, and paired t-tests were used to compare repeated measurements in identified individual fish. Difference in means between groups at multiple time-points was calculated using repeated measures ANOVA. Intra-observer and inter-observer agreement of continuous variables between two raters was assessed  and GraphPad Prism 6 (www.graphpad.com/prism).Means±s.d. were used to report normally distributed continuous variables, whereas medians and interquartile ranges were used to report variables that were not normally distributed. Unpaired assessed . Intra-c


HS), the most common cause of refractory temporal lobe epilepsy, is associated with hippocampal volume loss and increased T2 signal. These can be identified on quantitative imaging with hippocampal volumetry and T2 relaxometry. Although hippocampal segmentation for volumetry has been automated, T2 relaxometry currently involves subjective and time‐consuming manual delineation of regions of interest. In this work, we develop and validate an automated technique for hippocampal T2 relaxometry.Hippocampal sclerosis  and a template database. Voxelwise T2 maps were determined using a monoexponential fit. The hippocampal segmentations were registered to the T2 maps and eroded to reduce partial volume effect. Voxels with T2 >170 msec excluded to minimize cerebrospinal fluid (CSF) contamination. Manual determination of T2 values was performed twice in each subject. Twenty controls underwent repeat scans to assess interscan reproducibility.Fifty patients with unilateral or bilateral HS (p < 0.001), and a smaller but significant contralateral increase. The combination of hippocampal volumes and T2 values separated the groups well. There was a strong correlation between automated and manual methods for hippocampal T2 measurement . Interscan reproducibility was superior for automated compared to manual measurements.Hippocampal T2 values were reliably determined using the automated method. There was a significant ipsilateral increase in T2 values in HS from healthy controls. There is good agreement with manual measurements, and the technique is more reproducible on repeat scans than manual measurement. This protocol can be readily introduced into a clinical workflow for the assessment of patients with focal epilepsy.Automated hippocampal segmentation can be reliably extended to the determination of hippocampal T2 values, and a combination of hippocampal volumes and T2 values can separate subjects with  Hippocampal sclerosis (HS) is characterized by volume loss and increased T2 signalQuantitative imaging with hippocampal volumetry and T2 relaxometry improves sensitivity in detecting HSHippocampal T2 values can be reliably determined using an automated technique, rather than time‐consuming manual delineationAutomated measurement shows an interscan reproducibility superior to that with manual measurementThe combination of hippocampal volumes and hippocampal T2 values can reliably identify sclerotic hippocampiThe most common cause of medically refractory temporal lobe epilepsy (TLE) is hippocampal sclerosis (HS) characterized by neuronal cell loss and gliosis within the hippocampus, particularly CA1, CA3, and the dentate gyrus.1‐weighted and increased T2‐weighted signal.Typical MRI features of HS include hippocampal atrophy, disrupted internal hippocampal structure, and decreased THippocampal volumetry can quantify volume loss (atrophy), representing neuronal cell loss that may be difficult to appreciate visually.T2 relaxometry measures T2 relaxation time, an intrinsic tissue property. It may detect subtle pathology, which is useful in lateralizing temporal lobe epilepsy, even in the absence of hippocampal atrophy,The current clinical approach to hippocampal T2 measurement involves manual delineation of circular/elliptical regions of interest (ROIs).We selected 50 patients who had undergone brain MRI with an epilepsy protocol as part of routine clinical practice for TLE at the Epilepsy Society MRI Unit, Chalfont St Peter, and which been reported by a neuroradiologist as showing unilateral or bilateral HS on visual assessment . We recruited 50 healthy controls  without any history of neurologic or psychiatric disease.The study was considered a service evaluation using clinically acquired data by the National Hospital for Neurology and Neurosurgery and the Institute of Neurology Joint Research Ethics Committee. Informed written consent was obtained from control subjects.1‐weighted inversion‐recovery fast spoiled gradient recalled echo  224 × 256 × 256 mm, matrix 224 × 256 × 256, parallel imaging acceleration factor 2) and a coronal dual‐echo fast recovery fast spin echo proton‐density/T2‐weighted .Subjects underwent imaging on a 3T GE MR750 scanner with a 32‐channel coil. Sequences included a three‐dimensional (3D) T1‐weighted volume using a multi‐atlas–based segmentation algorithm (STEPS) and a template database of 400 manual segmentations as previously described . Hippocampal volumes were corrected for intracranial volume using linear regression with parameters derived from a group of healthy controls.Hippocampi were automatically segmented from the T1, S2 at the two echo times TE1, TE2: Voxelwise T2 maps were determined using a monoexponential fit1‐weighted image to the dual‐echo PD/T2 image was calculated using NiftyReg (https://sourceforge.net/projects/niftyreg) and applied to the hippocampal segmentations. The segmentations were eroded and voxels with T2 values >170 msec were eliminated to minimize cerebrospinal fluid (CSF) contamination , applying the above rigid transformation and measuring T2 values in the control subjects in each compartment. The distributions were reviewed to determine the optimal cutoff between the upper tail of T2 values in gray matter and the lower tail in CSF.A rigid transformation from the T1‐weighted image obtained from our online hippocampal segmentation website (https://hipposeg.cs.ucl.ac.uk) and a locally calculated T2 map is available at https://github.com/sjoerdvos/hippocampal_T2.A script for determining hippocampal T2 values using the hippocampal segmentations from a TFor comparison to previous practice, a radiographer manually determined hippocampal T2 values using elliptical ROIs on consecutive coronal slices Fig. E, and thTo compare interscan reproducibility of automated and manual measurement, 20 controls underwent repeat imaging on a separate occasion with the same protocol. Hippocampal T2 measurements were performed on the repeat scan with the automated and manual methods.t‐test assuming equal variances. Gender and laterality effects in healthy controls were determined with two‐tailed independent samples and paired t‐tests, respectively.All statistical analysis was performed in IBM SPSS Statistics 24. Hippocampal volumes and hippocampal T2 values were normally distributed in each group according to the Shapiro‐Wilks test. Statistical comparison between groups was therefore made using a two‐tailed independent samples Binary logistic regression was used to assess the classification of left and right hippocampi separately into pathologic or nonpathologic using the corresponding hippocampal volumes and hippocampal T2 values, both independently and combined.Agreement between the automated and manual methods for determining hippocampal T2 was determined by correlation, as although the general distribution of values should be similar, exact agreement between the methods would not be expected due to the different sampling.t‐test to check for equality of means.The reproducibility of T2 measurements between repeat scans in the same subject was assessed using Bland‐Altmann plots and a paired Hippocampal volumes and T2 values were reliably determined using the automated method Fig. , with got‐test, p < 0.001 for both) and bilateral HS (p < 0.001 for both) compared to controls. Right hippocampal volumes were significantly reduced and right hippocampal T2 significantly increased in right HS (p < 0.001 for both) and bilateral HS (p < 0.001 for both).Left hippocampal volumes were significantly reduced and left hippocampal T2 significantly increased in both left HS  and mean left hippocampal T2 mildly increased by 2.7 msec in right HS (p = 0.026).There were no significant differences between male and female controls in hippocampal volumes or hippocampal T2 values. There were no laterality effects for hippocampal volume, but mean hippocampal T2 values were significantly lower on the left than the right, with both automated  and manual (p = 0.034) measurements.3 and 108.5–123.8 msec, respectively. Although this combines both sides, the relevant upper end of the reference range for hippocampal T2 was indistinguishable between the left (123.6 msec) and right (123.9 msec) hippocampi individually.Reference ranges for hippocampal volumes and hippocampal T2 values determined from the healthy controls as mean ± 1.96 standard deviations (SDs) were 2.51–3.55 cmThe combination of hippocampal volume and T2 values gave good visual separation between groups Fig. . Binary There was a strong correlation between the automated and manual methods for determining hippocampal T2 Fig.  with PeaBland‐Altman plots confirmed that hippocampal T2 measurements were reproducible between repeat scans. The pairwise differences in hippocampal T2 were not significantly different from zero for either automated or manual measurements. However, the standard deviation of the differences was greater for manual (6.00 msec) than for automated (3.59 msec) measurement, leading to wider intervals on the Bland‐Altman plot.Automated hippocampal segmentation can be reliably extended to the determination of hippocampal T2 values, and a combination of hippocampal volumes and T2 values can separate subjects with HS from healthy controls. We found good agreement with manual measurements and an improved reproducibility on repeat scans compared to manual measurements.2‐weighted hyperintensity, one of the key radiologic features of HS, can be objectively assessed by quantitative measurement of T2 relaxation (T2 mapping) with increased sensitivity over visual reading.TThe initial scan protocols comprising multi‐echo Carr‐Purcell‐Meiboom‐Gill sequences were time‐consuming and gave limited spatial coverage.2‐weighted clinical acquisitions may be analyzedStandard T2 per slice to avoid CSF contamination so only sample a small part of the hippocampus. By using an automated segmentation, we could determine the mean T2 value in the entire hippocampus where cross‐sectional areas in a slice can exceed 50 mm2. CSF contamination was minimized by eroding the segmentation at the boundary and employing a threshold derived empirically from T2 values in gray matter and CSF of healthy controls.The established approach of manual placement of circular/elliptical ROIs is time‐consuming and the regions are necessarily limited in size to around 20 mmManual determination of hippocampal T2 values has been shown to be reproducible over time and unaffected by single seizures.There is a good correlation between manual and automated measurements, but the values are not in exact agreement with the slope of regression lines being below unity Fig. . This isHS is characterized histologically by cell loss and astrogliosis throughout mesial temporal limbic areas, especially the hippocampus.A notable finding is the bilateral changes observed in hippocampal T2 values even with apparently unilateral pathology. This has been observed in histopathologic studies1‐weighted image, but an alternative approach is whole‐brain voxel‐based relaxometry. This identifies changes in the temporal lobe white matter, amygdala, and parahippocampal gyrus,Our approach has been limited to hippocampal T2, but structural damage extends beyond the hippocampus.Patients in this study were selected according to visually apparent HS. Future work will include those with normal‐appearing hippocampi, but histologically identified HS following surgical treatment and the automated T2 mapping protocol will be introduced into our standard clinical workflow.We report a single value for each hippocampus representing the mean T2. As T2 values overlap between healthy controls and patients, it is critical that these single values are appropriately interpreted in a clinical setting in conjunction with hippocampal volumes, the clinical picture, and other available data.Hippocampal T2 values are higher anteriorly than posteriorly in healthy controls, and in HS, elevation of T2 values may occur diffusely or predominantly anteriorly.None of the authors has any conflict of interest to disclose. We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this report is consistent with those guidelines.


Mice are frequently used in research to examine outcomes of myocardial infarction (MI) and to investigate therapeutic interventions at an early pre-clinical stage. The MI model is generated by surgically occluding a major coronary artery, but natural variation in murine coronary anatomy can generate variable outcomes that will inevitably affect the accuracy of such investigations. The aim of this study was to use MRI to derive the most sensitive early variable that could be used to predict subsequent adverse cardiac remodelling in a male mouse model of MI.Using a longitudinal study design, heart structure and function were evaluated using cardiac MRI at one week following surgical MI to generate the early measurements and again at four weeks, when the scar had matured. The primary variables measured at week one were left ventricular volumes at end systole (LV-ESV) and at end diastole (LV-EDV), infarct size, LV-cardiac mass, and ejection fraction (EF).Univariate and multiple regression analyses showed that LV-ESV at one week following MI could be used to accurately predict various parameters of adverse LV remodelling at four weeks post-MI. However, the highest correlation was between LV-ESV at one week following MI and LV-EDV at four weeks , making LV-ESV at one week a valuable predictor variable of future adverse ventricular remodelling after MI.Using MRI to determine LV-ESV at an early stage following MI enables a more robust analysis of potential therapeutic interventions to ameliorate adverse cardiac remodelling. The resultant combination of cardiomyocyte death, inflammation and fibrosis leads to a situation where non-contractile scar tissue gradually replaces the infarcted myocardial tissue. Furthermore, increased pressure/volume load on the non-ischaemic myocardium leads to cardiac hypertrophy in non-infarcted areas, increasing the functional impairment of the affected ventricle and contributing to additional adverse remodelling. In parallel, systemic neurohormonal activation also contributes to progressive, adverse ventricular remodelling and development of heart failure Surgical occlusion of a major left ventricular coronary artery in a wild type mouse is frequently used to model myocardial infarction A range of studies have investigated baseline outcomes in mouse models of MI. For example, Shioura and colleagues showed that surgical ligation of the left main coronary artery in wild type (C57BL/6) male mice showed an initial drop in systolic function, followed by a transient improvement before further decline in both systolic and diastolic function that correlated with dynamic changes in foetal gene expression, characteristic of heart failure 22.1All in vivo procedures were conducted in accordance with the Guidance on the Operation of the Animals (Scientific Procedures) Act, 1986 (UK Home Office) and approved by the local ethics committee. Acute MI was created in 25 adult male C57BL/6 mice (12 to 14 weeks of age) using a procedure adapted from a published protocol 2.2Magnetic resonance images were acquired at 1 week and 4 weeks following MI surgery using a horizontal bore 7.0T Varian microimaging system  equipped with a 12-cm microimaging gradient insert (40 gauss/cm). Animals were anaesthetised with isoflurane via a facemask and positioned on a custom built sled , with integrated electrocardiographic (via electrodes fastened to the shaved chest with conductive hydro-gel), respiratory (via a pneumatic pillow) and cutaneous temperature monitoring. An SA Instruments Inc.  small animal system was used for physiological monitoring and gating. A 30 mm quadrature birdcage coil  was used to transmit/receive the MR signal. Scout images were used to ensure that the short and long axes of the left ventricle were correctly orientated. Global cardiac function was measured using an ECG triggered, respiratory gated gradient echo (FLASH) cine MR sequence using the following imaging parameters: TE 1.36 ms, TR 5 ms, flip angle 15°, matrix 128 × 128, field of view 25.6 mm × 25.6 mm, and 4 averages. The cardiac cycle was imaged across a minimum of 20 phases in all animals. Sufficient contiguous short axis slices of 1 mm thickness were obtained to cover the whole left ventricle.2.33) was calculated as the sum of myocardial area per slice (mm2) × number of slices × slice thickness (1 mm/slice). LV mass was calculated as myocardial volume times myocardial specific gravity (1.05 mg/mm3) and was presented as the average of mass independently calculated from end diastolic and end systolic measurements. Accurate measurement of MRI image analysis was confirmed in 3 ways: (i) no more than 5% difference in the myocardial mass calculated at end-diastole and end-systole; (ii) MR data was independently analysed by two investigators on 6 mice at both time points; and (iii) calculated mass showed good correlation with actual mass measured at autopsy (r = 0.91). To measure cardiac function, the LV chamber area outlined by the endocardial border for each slice at end diastole and end systole was measured and calculated for each slice at end diastole and end systole as LV volume per slice = LV area × slice thickness. The LV end-diastolic volume (LV-EDV) = ∑ LV volume per slice at end-diastole; and the LV end-systolic volume (LV-ESV) = ∑ LV volume per slice at end-systole. Functional parameters were calculated from these volumes as follows:MR images confirmed expected cardiac changes  and shorep and Ien) as a proportion of total epicardial and endocardial circumference (Tep and Ten) across all slices as previously described ep/Tep + Ien/Ten) × 100.Infarcted tissue is characterised by thinned, akinetic myocardium and infarct volume was calculated as a percentage of the left ventricular myocardium at end-diastole by measuring epicardial and endocardial infarct length  to each of the outcome measures at 4 weeks  , and LV-ESVwk1 showed the highest correlation with LV-EDVwk4 , a major readout of adverse left ventricular remodelling. In addition, LV-ESVwk1 was highly correlated with increased LV-masswk4 . However, LV-ESVwk1 did not show the highest correlation with LV-EFwk4 , and it was LV-EFwk1 that showed the highest correlation with LV-EFwk4  (We first examined the relationship between each of five early variables at week 1 post-MI (LV-EDVV-EFwk4) . LV-ESVw× 10− 5) . Linear wk1 was the best predictor for LV-EFwk4 and inclusion of further week 1 variables  did not significantly improve the fit to the model. These data confirm that LV-ESVwk1 is a very useful predictor variable for detrimental cardiac remodelling outcomes  at one month following infarction. Furthermore, LV-ESVwk1 is the most robust predictor of later adverse cardiac remodelling, accounting for 98% of the variability in LV-EDVwk4. Any future intervention able to reduce late adverse remodelling would be expected to significantly reduce the slope of the linear regression line described by the equation: LV-EDVwk4 = 1.33(LV-ESVwk1) + 26 μl3  and no other variable made any significant contribution to the fit of the model. In contrast, LV-EF+ 26 μl3 A.4wk1 was a highly predictable measure of later adverse cardiac remodelling (LV-EDVwk4), with increased predictability over other MRI-derived measures of cardiac properties at week 1, including LV-EDV, heart mass and infarct size. The extent of adverse remodelling as judged by EDVwk4 was directly proportional to LV-ESVwk1 with small infarcts increasing by the same proportion as larger infarcts. This finding is in contrast to a previous study using female mice which observed a biphasic response, with smaller infarcts showing no progression wk1 to predict adverse remodelling, univariate correlation analysis showed that infarct size measured by simple manual tracing of thinned akinetic myocardium wk4 outcomes . Furthermore, laboratories without access to a pre-clinical MRI facility could potentially use evaluation of end diastolic diameter (EDD) by echocardiography as an alternative predictive measure at early time points post-MI, although caution is needed because this technique is open to more subjective interpretation than MRI.Reported benefits that attenuate LV dilatation and improve heart function in pre-clinical studies using mice are rarely translatable in clinical trials Progressive ventricular dilatation after myocardial infarction is part of a complex cardiac remodelling process involving changes in mass, shape and volume 4.1ApoE mutant mice) would provide a more clinically relevant study population. We also acknowledge that measurement of cardiac function at 1 week post-MI would not provide a useful baseline for measuring early cardioprotective treatments, e.g. ischaemic pre-conditioning where reproducible benefit can be seen in pre-clinical models at 48 h post-MI Limitations of using mouse models of clinical MI include the different coronary anatomy of mice and humans 5Our findings suggest that MRI evaluation of LV-ESV at one week following MI in mouse models can be used to accurately predict subsequent adverse remodelling and therefore represents a reliable baseline measure to facilitate a more robust analysis of interventions to ameliorate adverse progression of cardiac remodelling following MI.The authors report no relationships that could be construed as a conflict of interest.British Heart Foundation (RG/12/2/29416). STC was funded by an Intra-European Marie Curie Fellowship (329813 VASC-GEN) and JES is a British Heart Foundation Senior Basic Science Research Fellow (FS/11/50/29038).This work was funded by a programme grant from the