The echocardiographic study of the rabbit heart left ventricle morpho-functional parameters

Morphometric and functional parameters of the heart left ventricle in rabbits during systole and diastole were investigated by the method of echocardiography. Morphometric parameters were studied on three levels: the mitral valve, the papillary muscles and the apical level. The internal dimension of the left ventricle uniformly decreases in three parallel planes during systole, its maximal reduction being observed on the apical level. During the contraction phase, the posterior wall thickness of the left ventricular and the interventricular septum thickness increases on the basal level to a greater extent than on the apical one. During systole, the interventricular septum movement is greater than the left ventricular posterior wall motion. During the heart cycle, the form of the left ventricular cavity changes from an ellipsoid in diastole to elliptic paraboloid in systole.     

超声心动图结合血清miR-122对原发性高血压所致左心室功能改变的评估价值

摘要 目的：探讨超声心动图结合血清微小RNA-122（miR-122）对原发性高血压（EH）所致左心室功能改变的评估价值。方法：选择2020年01月-2022年06月本院收治的58例EH患者作为研究组,另选择同期62例体检健康者作为对照组。所有研究对象均行超声心动图检查、血清miR-122检测,比较两组间超声心动图定量参数、血清miR-122水平差异,分析血清miR-122与左心室功能指标的相关性。通过绘制受试者工作特征曲线（ROC）并计算曲线下面积（AUC）分析超声心动图定量参数、血清miR-122单独诊断EH所致左心室功能改变的最佳诊断阈值以及相应敏感度、特异度;联合诊断采用多因素Logistic回归分析并绘制ROC曲线评估其诊断效能。结果：研究组患者左心室舒张末期内径（LVEDD）、左心室收缩末期内径（LVESD）、室间隔舒张末期厚度（IVSD）、左心室后壁舒张末期厚度（LVPWD）、E与室间隔和侧壁处二尖瓣环舒张早期运动速度e''室间隔和e''侧壁均值的比值（E/e''）、左心室舒张末期容积（EDV）和左心室收缩末期容积（ESV）、血清miR-122水平显著高于对照组（P<0.05）,二尖瓣口舒张早期血流速度E与舒张晚期血流速度A比值（E/A）显著低于对照组（P<0.05）,而两组间左心室射血分数（EF）差异不具有统计学意义（P＞0.05）。血清miR-122水平与LVEDD、LVESD、EDV、ESV呈正相关(P<0.05）,与其他超声心动图定量参数IVSD、LVPWD、EF、E/A、E/e''无显著相关性（P＜0.05）。与单独诊断相比较,超声心动图定量参数结合血清miR-122诊断EH所致左心室功能改变的AUC、约登指数、敏感度、特异度最高。结论：超声心动图结合血清miR-122能够准确评估EH所致左心室功能改变情况,有助于指导临床治疗方案的选择。     

血清胱抑素C 水平与糖尿病心室重构关系的临床研究

目的:研究血清胱抑素C水平与糖尿病心室重构的关系。方法:选择2013年10月~2015年10月在我院进行诊治的糖尿病患者90例,检测血清胱抑素C水平,按照糖尿病患者血清胱抑素C水平的中位数,分为正常组(胱抑素C水平1.65mg/L)和升高组(胱抑素C水平1.65mg/L)。行超声心动图检测左室舒张末内径、左房内径、左室舒张末容积、室间隔厚度和左室后壁厚度,并计算出左室质量指数。对两组的这些指标进行比较,并分析血清胱抑素C与糖尿病心室重构的相关性。结果:与正常组相比,升高组的胱抑素C、左室舒张末内径、左房内径、室间隔厚度、左室后壁厚度、左室质量指数和脑钠肽水平均明显增高(P0.05);经过相关性分析,血清胱抑素C水平与左室舒张末内径、左房内径、室间隔厚度、左室后壁厚度、左室质量指数和脑钠肽均呈正相关(P0.05);Logistic回归分析显示左室舒张末内径、左房内径、室间隔厚度、左室后壁厚度、左室质量指数和脑钠肽等是胱抑素C水平升高的危险因素。结论:血清胱抑素C水平与糖尿病患者的心功能和心室重构具有明显相关性,可作为衡量糖尿病患者心室重构程度的一项参考指标。     

曲美他嗪联合麝香保心丸治疗急性心肌梗死的效果研究

目的:研究曲美他嗪(TMZ)联合麝香保心丸(HMP)治疗急性心肌梗死的效果。方法:采用40只雄性C57BL/6J小鼠构建急性心肌梗死模型,随机分成4组,每组10只:(1)假手术组;(2)心肌梗死组;(3)心肌梗死+TMZ组(TMZ 20 mg/Kg灌胃,3次/天);(4)心肌梗死+TMZ+HMP组(HMP 14 mg/Kg灌胃,3次/天)。2周后行心脏超声检查采集心功能参数左室舒张末内径、左室收缩末内径、室间隔厚度、舒张末期左室后壁厚度及射血分数。同时,对心脏标本行形态学分析。结果:TMZ+HMP组左室舒张末内径、左室收缩末内径、舒张末期左室后壁厚度及射血分数均优于于TMZ组(均为P0.05)。心肌组织HE及PSR染色显示TMZ+HMP组心肌细胞坏死及纤维化程度较其余组低。结论:曲美他嗪联合麝香保心丸治疗急性心肌梗死的效果较单用曲美他嗪更加显著。     

Echocardiographic parameters and indices in the normal beagle dog.

M-mode and two-dimensional echocardiographic measurements were made from the right sternal border of 50 healthy Beagles (25 males and 25 females) approximately 7 months old. The dogs were conscious and standing during the investigation. The following parameters, in systole and diastole, were measured on the echocardiographic images: left ventricular posterior wall thickness (LVWT); intraventricular septum thickness (IST); left ventricular internal dimension (LVID); and circumference (LVC). Fractional shortening (FS) and ejection fraction (EF) were also calculated. Mean, standard deviation, range and coefficient of variation are reported for each echocardiographic parameter and for body weight. Males and females were considered separately and together. Each parameter was analysed statistically to check for differences between the sexes and for correlations with body weight. A statistically significant difference between the sexes was only observed for LVWT in systole and diastole. A linear regression with body weight was obtained only for LVID in systole and in diastole. The results show that morphofunctional cardiac homogeneity is independent of size in dogs of this breed and age.     

α-酮酸片对维持性血液透析患者心脏功能和结构的影响

目的：探讨α-酮酸片（α-KA）对维持性血液透析（MHD）患者心脏功能和结构的影响。方法：观察30例α-酮酸片（商品名：开同）治疗组维持性血液透析患者与30例对照组患者,分别在治疗前及治疗6个月后超声心动图测定心脏结构指标：左房收缩末期内径（LADs）、左室舒张末期内径（LVEDd）、室间隔舒张末期厚度（IVSTd）、左室后壁舒张末期厚度（LVPWTd）,左房内径指数（LAI）、左心室心肌重量指数（LVMI）、相对室壁厚度（RWT）,心脏功能指标：左室射血分数（LVEF）,左室短轴缩短率（FS）,二尖瓣口舒张早期和晚期最大血流速度比（E/A）各项指标等检测,比较治疗前后各指标变化。结果：治疗组MHD患者心脏结构指标：左房收缩末期内径（LADs）、左室舒张末期内径（LVEDd）、室间隔舒张末期厚度（IVSTd）、左室后壁舒张末期厚度（LVPWTd）,左房内径指数（LAI）、左心室心肌重量指数（LVMI）值均明显低于对照组,二者差异有显著性（P〈0.05）,两组相对室壁厚度（RWT）相比没有明显的差异（P〉0.05）。心脏功能指标：左室射血分数（LVEF）,左室短轴缩短率（FS）,二尖瓣口舒张早期和晚期最大血流速度比（E/A）值较对照组明显增高（P〈0.05）,有统计学意义。结论：α-酮酸片可以改善MHD患者的心脏结构和功能,其对MHD患者心血管并发症的预防和治疗有一定临床指导意义。     

The dynamics of contraction and walls motion of the calf heart left ventricle

The echocardiographic research of the left ventricular has revealed heterogeneity of thickness of the posterior wall and interventricular septum in three parallel planes in the transverse direction of the left ventricle in calves. The amplitude of systolic motion of the left ventricle posterior wall is larger than that of the interventricular septum at the level of the mitral valve, at the level of the papillary muscles, and at the apical level. The excursion of left ventricular walls in the basal level is twice as large as the mobility of ventricular walls in the apical level. During the contraction of the myocardium, the shortness of the left ventricular transversal diameter is to great extent determined by the degree of contraction of the left ventricular wall rather than of the interventricular septum. The high contractility is revealed in calves.     

缬沙坦对维持性血液透析患者心脏功能和结构的影响

目的:探讨缬沙坦对维持性血液透析(maintenance hemodialysis,MHD)患者心脏功能和结构的影响。方法:100例MHD患者,随机分为治疗组(50例)与对照组(50例),对照组仅予基础治疗,治疗组加予口服缬沙坦治疗,总疗程为6个月。观察治疗前后超声心动图指标变化。结果:与治疗前及对照组同期比较,治疗组心脏结构指标左房收缩末期内径(LAD)、左室舒张末期内径(LVDD)、室间隔厚度(IVST)、左室后壁厚度(LVPWT)、左房内径指数(LAI)、左室重量指数(LVMI)及相对室壁厚度(RWT)有所降低,心脏功能指标:左室射血分数(LVEF),左室短轴缩短率(FS),二尖瓣口舒张早期和晚期最大血流速度比(E/A)值有所提高,差异均有统计学意义(P<0.05)。对照组超声心动图各项指标与治疗前相比变化不明显(P>0.05)。结论:缬沙坦能延缓或逆转左心室肥厚,明显改善左室舒张功能,有助于改善MHD患者心脏重构,改善心脏功能,从而延缓慢性肾功能衰竭尿毒症期患者的左心室重塑,降低心血管疾病的发生率和死亡率。缬沙坦对MHD患者心血管疾病并发症的预防和治疗及提高MHD患者生存率有一定临床指导意义。     

THE EFFECT OF AEROBIC CONTINUOUS AND INTERVAL TRAINING ON LEFT VENTRICULAR STRUCTURE AND FUNCTION IN MALE NON-ATHLETES

Exercise plays an important role to improve cardiovascular performance. The aim of this study was to compare the effect of aerobic continuous and interval training on the left ventricular structure and function. Twenty untrained healthy male students (aged 18-22 years) were randomly divided into two groups: continuous (C; n = 10) and interval (I; n = 10). The training programme consisted of countryside jogging for 45 min during 8 weeks three times a week at 70% of maximum heart rate (MHR). In each session group C was jogging for 45 min and in group I jogging was performed in 5 nine-minute stages with a four-minute inactive rest between them. M-mode, 2-dimensional, colour and Doppler transthoracic echocardiography were performed, during resting conditions, before and after the training period. After 8-week training the end diastolic diameter, systolic blood pressure and diastolic blood pressure in groups C and I, and the posterior wall thickness and the end systolic diameter in group I showed no significant difference (P > 0.05). On the other hand, the percentage of ejection fraction and shortening fraction in groups C and I, the end systolic diameter and the posterior wall thickness in group C and the interventricular septum thickness in group I demonstrated a significant difference (P ≤ 0.05). Comparing the two groups, only the value of the interventricular septum thickness was significant (P ≤ 0.05). In general, eight-week aerobic continuous and interval training can affect left ventricular structure and function.     

Prevention of concentric hypertrophy and diastolic impairment in aortic-banded rats treated with resveratrol

This study was designed to examine the effects of the antioxidant resveratrol on cardiac structure and function in pressure overload (PO)-induced cardiac hypertrophy. Male Sprague-Dawley rats were subjected to sham operation and the aortic banding procedure. A subgroup of sham control and aortic-banded rats were treated with resveratrol for 2 wk after surgery. Echocardiographic analysis of cardiac structure and function along with Western blot analysis of endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS), and redox factor-1 (ref-1) were performed in all groups after 4 wk of surgery. Banded rats showed significantly increased left ventricle-to-body weight ratio. Echocardiographic analysis showed that the interventricular septal wall thickness and left ventricular posterior wall thickness at systole and diastole were significantly increased in banded rats. Also, a significant increase in isovolumic relaxation time was observed in banded rats. Measured eNOS, iNOS, and ref-1 protein levels were significantly reduced in banded rats. Resveratrol treatment prevented the above changes in cardiac structure, function, and protein expression in banded rats. Aortic banding after 4 wk resulted in concentric remodeling and impaired contractile function due to PO on the heart. The 2-wk treatment with resveratrol was found to abolish PO-induced cardiac hypertrophy. Resveratrol may therefore be beneficial against PO-induced cardiac hypertrophy found in clinical settings of hypertension and aortic valve stenosis.     

Effect of endurance training on cardiac morphology in Alaskan sled dogs

The cardiac morphology of 77 consciousAlaskan sled dogs before and after 5 mo of endurance training (20 km/day team pulling a sled and musher) was studied usingtwo-dimensional and M-mode echocardiography. Subgroups included dogswith at least one season of previous training ("veterans") anddogs undergoing their first season of training ("rookies").Training resulted in a significant (P < 0.05) decrease in resting heart rate (15%) and significant increases in interventricular septal thickness (systole, 15%; diastole, 13%), left ventricular (LV) internal dimension in diastole (LVIDd, 4%), LV free wall thickness in systole (9%) and diastole (LVWd, 9%), and left atrial diameter (5%) in all dogs, but the increase in LVWd was greater in rookies (16%) than in veterans (7%).Training increased end-diastolic volume index (8%), LV mass index(24%), and heart weight index (24%) and decreased the LVIDd-to-LVWd ratio (6%) but did not alter cardiac index. We conclude that increased LV mass attributable to LV dilation and hypertrophy isassociated with endurance training in Alaskan sled dogs.Disproportionate LV wall thickening accompanying LV dilation suggeststhat cardiac morphological changes are due to volume and pressureloading. These training-induced changes are similar to those documented in human athletes undergoing combined isometric and isotonic training and differ from studies of dogs trained on treadmills.

     

Influence of posture on left ventricular long- and short-axis shortening

End-diastolic volume and left ventricular stroke volume are increased in the supine compared with upright position, but the contribution of long-axis (LAS) and short-axis shortening (SAS) to these changes with change in posture has not been established. We examined long- and short-axis motion and dimensions with echocardiography in 10 healthy subjects in the upright and supine position. Long-axis length at end diastole was almost identical, whereas the diastolic short-axis diameter was increased in the supine position. At end systole, there was a decreased long-axis length and increased short-axis length in the supine vs. upright position. Both LAS and SAS were enhanced in supine vs. upright positions [LAS: 9.3 +/- 2.2 vs. 15.1 +/- 3.1 mm (P < 0.001); SAS: 12.7 +/- 3.2 vs. 16.3 +/- 2.8 mm (P < 0.001)], presumably via Starling mechanisms. LAS increased more in the lateral part of the mitral annulus than in the septal part [7.7 +/- 2.6 vs. 4.0 +/- 2.8 mm (P < 0.006)], which implies that the more spherical form, in the supine position, induces more stretch at the lateral free wall than in the ventricular septum. These findings support the notion that Starling mechanisms affect systolic LAS.     

Cineangiographic diagnosis of an aneurysm of the membranous part of the heart septum

Altogether 20 patients with aneurysm of the cardiac membranous septum (AMS) were examined. Biplane cineangiocardiography (CACG) of the left ventricle was performed in the left oblique position permitting the detection of AMS in 17.8% of the patients with the suspected interventricular septal defect (IVSD). Heart diseases were observed in all the patients, in 90% they were accompanied by IVSD in the cardiac wall. AMS regular contours and a wide base were signs of true AMS. A narrow base and irregular shape were indicative of false AMS. Slight aortic transposition was noted in 1/4 of the patients with AMS.     

Direct and series transmission of left atrial pressure perturbations to the pulmonary artery: a study using wave-intensity analysis

Pressure waves are thought to travel from the left atrium (LA) to the pulmonary artery (PA) only retrogradely, via the vasculature. In seven anesthetized open-chest dogs, a balloon was placed in the LA, which was rapidly inflated and deflated during diastole, early systole, and late systole. High-fidelity pressures were measured within and around the heart. Measurements were made at low volume [LoV; left ventricular end-diastolic pressure (LVEDP) = 5-9 mmHg], high volume (HiV; LVEDP = 16-19 mmHg), and HiV with the pericardium removed. Wave-intensity analysis demonstrated that, except during late systole, balloon inflation created forward-going PA compression waves that were transmitted directly through the heart without measurable delay; backward PA compression waves were transmitted in-series through the pulmonary vasculature and arrived after delays of 90 +/- 3 ms (HiV) and 103 +/- 5 ms (LoV; P < 0.05). Direct transmission was greater during diastole, and both direct and series transmission increased with volume loading. Pressure waves from the LA arrive in the PA by two distinct routes: rapidly and directly through the heart and delayed and in-series through the pulmonary vasculature.     

模拟高原低压低氧环境对大鼠心脏结构和功能影响*

目的: 探讨模拟海拔7 000 m低压低氧环境对大鼠心脏结构和功能的影响。方法: 96只雄性SD大鼠随机分为常压常氧对照组(对照组)和高原低压低氧组(低氧组)。低氧组大鼠放置于大型多因素复合环境模拟实验舱内,模拟海拔7 000 m高原环境饲养。实验舱运行时间23 h/d,控制昼夜比大约12 h∶12 h;对照组置于相同条件的常压常氧环境下饲养。低氧组又根据低氧时间不同分为3 d组、7 d组、14 d组和28 d组,同时设置与各低氧组相对应的对照组,每组均12只大鼠。应用超声心动图、心电图、血常规、血生化综合评价高原低压低氧环境下大鼠心脏结构和功能变化,心肌组织HE染色分析心肌组织病理变化。结果: 与相同时间点对照组比较①随着低压低氧暴露时间延长,大鼠体质量增长明显缓慢,动脉血氧饱和度14 d和28 d显著降低(P＜0.05)。②低氧组大鼠左心室舒张末期前壁厚度(LVAWD)及左心室舒张末期后壁厚度(LVPWD)于28 d时显著升高(P＜0.05)。舒张末期左心室腔直径(LVIDD)及收缩末期左心室腔直径(LVIDS)于28 d时明显降低(P＜0.05,P＜0.01)。左心室射血分数(EF%)、左室短轴缩短率(FS%)、肺静脉血流峰值速度(PV peak velocity)及肺静脉血流峰梯度(PV peak gradient)于低氧7 d 下降明显(P＜0.05,P＜0.01),低氧14 d 及低氧28 d 恢复。③低氧组大鼠心电图QRS间期与QT间期在14 d 及28 d 显著延长(P＜0.05,P＜0.01)。ST段3 d和7 d显著压低(P＜0.05,P＜0.01)。R波振幅于 7 d、14 d 及28 d 显著降低(P＜0.05,P＜0.01)。④低氧各组大鼠红细胞计数(RBC)、血红蛋白(HGB)、红细胞分布宽度(RDW)均明显升高(P＜0.01)。血小板计数(PLT)于14 d 及28 d 明显下降(P＜0.01)。血肌酐(CR)于14 d及28 d显著升高(P＜0.05)。⑤心肌病理提示,低氧3 d 和7 d 可见心肌水肿、肌浆凝聚,横纹不清,灶状变性和坏死伴炎性细胞浸润。低氧14 d 和28 d 心肌组织炎症性病理损伤逐渐减少。心肌细胞逐渐肥大,成纤维细胞逐渐增生。心肌间质胶原纤维逐渐增多等心肌代偿修复性病理变化显著。结论: 暴露于模拟海拔7 000 m低压低氧环境下3 d大鼠心功能明显降低,7 d最为显著。     

Impaired left ventricular filling due to right-to-left ventricular interaction in patients with pulmonary arterial hypertension

The aim of this study was to investigate the contribution of direct right-to-left ventricular interaction to left ventricular filling and stroke volume in 46 patients with pulmonary arterial hypertension (PAH) and 18 control subjects. Stroke volume, right and left ventricular volumes, left ventricular filling rate, and interventricular septum curvature were measured by magnetic resonance imaging and left atrial filling by transesophageal echocardiography. Stroke volume, left ventricular end-diastolic volume, and left ventricular peak filling rate were decreased in PAH patients compared with control subjects: 28 +/- 13 vs. 41 +/- 10 ml/m(2) (P < 0.001), 46 +/- 14 vs. 61 +/- 14 ml/m(2) (P < 0.001), and 216 +/- 90 vs. 541 +/- 248 ml/s (P < 0.001), respectively. Among PAH patients, stroke volume did not correlate to right ventricular end-diastolic volume or mean pulmonary arterial pressure but did correlate to left ventricular end-diastolic volume (r = 0.62, P < 0.001). Leftward interventricular septum curvature was correlated to left ventricular filling rate (r = 0.64, P < 0.001) and left ventricular end-diastolic volume (r = 0.65, P < 0.001). In contrast, left atrial filling was normal and not correlated to left ventricular end-diastolic volume. In PAH patients, ventricular interaction mediated by the interventricular septum impairs left ventricular filling, contributing to decreased stroke volume.     

超声心动图评价左室舒张性心力衰竭患者左心形态及舒张功能的应用价值

目的:研究超声心动图对左室舒张性心力衰竭(LVDHF)患者左心形态及舒张功能的评估价值。方法:选择2014年3月至2016年3月我院收治的LVDHF患者78例记为观察组,另选择同期健康志愿者80例记为对照组,两组受试者均进行血压、心率检查,并利用超声心动图技术检测两组受试者的心脏相关指标。结果:观察组的舒张压(DBP)、收缩压(SBP)、心率(HR)、左房内径(LAD)、室间隔厚度(IVST)、左室后壁厚度(LVPWT)、综合指标(E/Ea)及反向血流速度(Ar)水平均明显高于对照组,而早、晚期的运动速度比(Ea/Aa)、血流传播速度(Vp)及峰速比(S/D)水平明显低于对照组,差异均有统计学意义(P0.05)。结论:超声心动图能准确地反应LVDHF患者的左心形态以及舒张功能,可在临床进行推广。     

Contraction wave in axial direction in free wall of guinea pig left ventricle

Mechanical activation of the normal left ventricle (LV) is not simultaneous; however, the potential consequences of the ejection function of the ventricle are not entirely known. We studied contraction of the LV free wall to determine whether it reveals a contraction wave in the axial direction during ejection. Seven guinea pig hearts in situ were studied via thoracotomy. In each heart, the ventricular and aortic pressures were measured by two microtipped manometers (2-Fr, Millar). Contraction of the LV free wall was assessed with a video system (Dalsa D6-0256 camera and EPIX PIXCI D32 frame grabber; acquisition rate, 500 frames/s), and 15-18 epicardial markers were used to divide the region into 20-25 triangular areas. The area sizes were studied during contraction to locate the position of the contraction wave. For each triangular area, two variables were determined as follows: the time (t(c)) from the end of diastole until the size of the area reached 80% of maximum size reduction (normalized with the duration of systole) and the normalized latitude (L(ax)) of the area (determined at the end of diastole). A relationship between these two variables was determined by regression analysis. We found that the t(c) at which the contraction wave reached a triangular area was in positive correlation with the L(ax) value for that triangular area with a slope of 0.25 +/- 0.09 and a linear correlation coefficient of 0.41 +/- 0.08. Thus contraction in the guinea pig LV free wall occurs progressively from apex to base with successive areas reaching 80% contraction.     

Left ventricular hypertrophy in chronically hypertensive ponies

Systemic arterial hypertension is associated with equine laminitis, a disease precipitated by gross over-ingestion of carbohydrates. We examined the hearts from nine chronically hypertensive (161 +/- 11/99 +/- 6 mmHg) laminitic ponies and nine normotensive (128 +/- 2/76 +/- 3 mmHg) ponies postmortem for signs of left ventricular hypertrophy. The hypertensive ponies had hearts which were significantly larger (7.77 +/- 0.26 g/kg bodyweight (BW) vs. 5.67 +/- 0.22 g/kg BW), as well as increased combined left ventricle and septum weight (4.99 +/- 0.21 g/kg BW vs. 3.67 +/- 0.20 g/kg BW) and left ventricular free wall weight (3.71 +/- 0.23 g/kg BW vs. 2.62 +/- 0.19 g/kg BW) (p less than 0.05). The right ventricular free wall weights were not significantly different. Mean left ventricular free wall thickness was increased significantly in the hypertensive ponies compared to the normotensive group (26.1 +/- 0.4 mm and 22.5 +/- 1 mm, respectively), but neither septal nor right ventricular free wall thickness was different. These findings demonstrate that left ventricular hypertrophy accompanies equine laminitis-induced hypertension.     

Anatomic features of postmortem experimental ruptures of the human heart

Comparison of postmortem performed experimental cardiac ruptures with post-infarction lesions reveals uniformity of their localization. The ruptures are found to occur at places of a sharp change in the relief of the cardiac internal surface. These areas should be considered as concentrators of strain, promoting cardiac ruptures. In the left ventricle six concentrators of strain are revealed. They are: the place where the anterior part of the interventricular septum passes into the anterior wall of the left ventricle, the right edge of the papillary muscle, the left edge of the anterior papillary muscle, the left edge of the posterior papillary muscle, the right edge of the posterior papillary muscle, the place where the posterior part of the interventricular septum passes into the posterior wall of the left ventricle. Frequency of the experimental ruptures of the interventricular septum, under loading of the left ventricle, is demonstrated to depend on pressure in the right cardiac part.