Sheep can be used as animal model of regional myocardial remodeling and controllable work

Background: Pacing the right heart has been shown to induce reversible conduction delay and subse­quent asymmetric remodeling of the left ventricle (LV) in dogs and pigs. Both species have disadvantages in animal experiments. Therefore the aim of this study was to develop a more feasible and easy-to-use animal model in sheep. Methods: Dual-chamber (DDD) pacemakers with epicardial leads on the right atrium and right ven­tricular free wall were implanted in 13 sheep. All animals underwent 8 weeks of chronic rapid pacing at 180 bpm. Reported observations were made at 110 bpm. Results: DDD pacing acutely induced a left bundle branch block (LBBB) — like pattern with almost doubling in QRS width and the appearance of a septal flash, indicating mechanical dyssynchrony. Atrial pacing (AAI) resulted in normal ventricular conduction and function. During 8 weeks of rapid DDD pacing, animals developed LV remodeling (confirmed with histology) with septal wall thinning (–30%, p < 0.05), lateral wall thickening (+22%, p < 0.05), LV volume increase (+32%, p < 0.05), decrease of LV ejection fraction (–31%, p < 0.05), and functional mitral regurgitation. After 8 weeks, segmental pressure-strain-loops, representing regional myocardial work, were recorded. Switching from AAI to DDD pacing decreased immediately work in the septum and increased it in the lateral wall (–69 and +41%, respectively, p < 0.05). Global LV stroke work and dP/dtmax decreased (–27% and -25%, respectively, p < 0.05). Conclusions: This study presents the development a new sheep model with an asymmetrically remod­eled LV. Simple pacemaker programing allows direct modulation of regional myocardial function and work. This animal model provides a new and valuable alternative for canine or porcine models and has the potential to become instrumental for investigating regional function and loading conditions on regional LV remodeling

Risk factors for sudden cardiac death in hypertrophic cardiomyopathy

Aim of this study was the evaluation of six non invasive clinical indices as risk factors for sudden death (SD)in hypertrophic cardiomyopathy (HCM). Previous syncope, family history of SD, non sustained ventricular tachycardia, abnormalblood pressure response during exercise, excessive hypertrophy ≥3 cm and left ventricular outflow tract obstructionwith a peak gradient ≥30 mmHg were evaluated in a cohort of 166 patients(112 males, 51.8 ± 15.6 years), followed up for amedian of 32.4 months (range 1 to 209 months). During follow up 13 patients reached study’s endpoints: SD, cardiac arrest,documented sustained ventricular tachycardia and/or Implantable Cardioverter Defibrillator (ICD)-discharge. Patients havingexperienced syncope or presenting with a Maximum Wall Thickness ≥3cm in echocardiography were more sensitive to SDemergence since they had a 13.07 (95%CI: 4.00-46.95, p < 0.0001) and a 10.07 (95%CI: 2.92-34.79, p = 0.003) greater relativerisk respectively. In our cohort of patients only two of the six ‘recognised’ potential risk factors for SD were found sensitive,a result causing scepticism about the validity of criteria used for ICD implantation in HCM patients for SD prevention

Identification of high risk patients with hypertrophic cardiomyopathy in a northern Greek population

This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Hypertrophic cardiomyopathy with midventricular obstruction and apical aneurysm formation in a single family: case report

<p>Abstract</p> <p>Background</p> <p>Hypertrophic cardiomyopathy (HCM) is an extremely heterogeneous disease. An under recognized and very often missed subgroup within this broad spectrum concerns patients with left ventricular (LV) apical aneurysms in the absence of coronary artery disease.</p> <p>Case presentation</p> <p>We describe a case of HCM with midventricular obstruction and apical aneurysm formation in 3 patients coming from a single family. This HCM pattern was detected by 2D-echocardiography and confirmed by cardiac magnetic resonance imaging. A cardioverter defibrillator was implanted in one of the patients because of non-sustained ventricular tachycardia detected in 24-h Holter monitoring and an abrupt drop in systolic blood pressure during maximal exercise test. The defibrillator activated 8 months after implantation by suppression of a ventricular tachycardia providing anti-tachycardia pacing. The patient died due to refractory heart failure 2 years after initial evaluation. The rest of the patients are stable after a 2.5-y follow-up period.</p> <p>Conclusion</p> <p>The detection of apical aneurysm by echocardiography in HCM patients may be complicated. Ventricular tachycardia arising from the scarred aneurysm wall may often occur predisposing to sudden death.</p

Machine learning of the spatio-temporal characteristics of echocardiographic deformation curves for infarct classification

The aim of this study was to analyze the whole temporal profiles of the segmental deformation curves of the left ventricle (LV) and describe their interrelations to obtain more detailed information concerning global LV function in order to be able to identify abnormal changes in LV mechanics. The temporal characteristics of the segmental LV deformation curves were compactly described using an efficient decomposition into major patterns of variation through a statistical method, called Principal Component Analysis (PCA). In order to describe the spatial relations between the segmental traces, the PCA-derived temporal features of all LV segments were concatenated. The obtained set of features was then used to build an automatic classification system. The proposed methodology was applied to a group of 60 MRI-delayed enhancement confirmed infarct patients and 60 controls in order to detect myocardial infarction. An average classification accuracy of 87% with corresponding sensitivity and specificity rates of 89% and 85%, respectively was obtained by the proposed methodology applied on the strain rate curves. This classification performance was better than that obtained with the same methodology applied on the strain curves, reading of two expert cardiologists as well as comparative classification systems using only the spatial distribution of the end-systolic strain and peak-systolic strain rate values. This study shows the potential of machine learning in the field of cardiac deformation imaging where an efficient representation of the spatio-temporal characteristics of the segmental deformation curves allowed automatic classification of infarcted from control hearts with high accuracy

Comparison of Feasibility, Accuracy, and Reproducibility of Layer-Specific Global Longitudinal Strain Measurements Among Five Different Vendors: A Report from the EACVI-ASE Strain Standardization Task Force

BACKGROUND: Despite standardization efforts, vendors still use information from different myocardial layers to calculate global longitudinal strain (GLS). Little is known about potential advantages or disadvantages of using these different layers in clinical practice. The authors therefore investigated the reproducibility and accuracy of GLS measurements from different myocardial layers. METHODS: Sixty-three subjects were prospectively enrolled, in whom the intervendor bias and test-retest variability of endocardial GLS (E-GLS) and midwall GLS (M-GLS) were calculated, using software packages from five vendors that allow layer-specific GLS calculation (GE, Hitachi, Siemens, Toshiba, and TomTec). The impact of tracking quality and the interdependence of strain values from different layers were assessed by comparing test-retest errors between layers. RESULTS: For both E-GLS and M-GLS, significant bias was found among vendors. Relative test-retest variability of E-GLS values differed significantly among vendors, whereas M-GLS showed no significant difference (range, 5.4%-9.5% [P = .032] and 7.0%-11.2% [P = .200], respectively). Within-vendor test-retest variability was similar between E-GLS and M-GLS for all but one vendor. Absolute test-retest errors were highly correlated between E-GLS and M-GLS for all vendors. CONCLUSIONS: E-GLS and M-GLS measurements showed no relevant differences in robustness among vendors, although intervendor bias was higher for M-GLS compared with E-GLS. These data provide no technical argument in favor of a certain myocardial layer for global left ventricular functional assessment. Currently, the choice of which layer to use should therefore be based on the available clinical evidence in the literature

Layer-Specific Segmental Longitudinal Strain Measurements: Capability of Detecting Myocardial Scar and Differences in Feasibility, Accuracy, and Reproducibility, Among Four Vendors A Report From the EACVI-ASE Strain Standardization Task Force

BACKGROUND: Segmental longitudinal strain (SLS) is reported to be vendor specific. Despite standardization efforts, vendors still use different myocardial layers for strain measurements. It is unclear, however, which layer is the most favorable for clinical purposes. Therefore, in this study we evaluated the reproducibility, accuracy, and scar detection ability of SLS measurements from different myocardial layers. METHODS: In data sets of 58 patients with prior myocardial infarction and five healthy volunteers, we measured the intervendor bias, the relative test-retest variability, and scar discrimination ability of endocardial and midwall SLS, using software packages from four different companies (GE, Siemens, Toshiba, and TomTec). Cardiac magnetic resonance delayed enhancement images were used as the reference standard of scar definition. RESULTS: Variability of SLS measurements was significant among the vendors for both midwall and endocardium. In addition, relative errors of SLS measurements varied considerably among vendors (P < .001 for both layers). Comparisons of test-retest errors from different layers for individual vendors did not show any significant differences. Regardless of the vendor, both endocardial and midwall strain values were decreased in scarred segments. Endocardial to midwall ratio of strain measurements showed no difference between scar-free and scarred segments. Endocardial and midwall strain parameters showed no significant difference in scar detection capability. CONCLUSIONS: Layer-specific SLS measurements vary significantly among vendors. Endocardial and midwall SLS measurements have a high yet comparable test-retest variability. Combining layer-specific SLS measurements does not provide additional information for detection of regional functional abnormalities. Our results do not provide evidence to favor the use of one myocardial layer over another