Traumatic disruption of the fibrous skeleton of the heart, with injury of the tricuspid and mitral valves, aortic annulus, and ventricular septum

In an automobile accident, a young man sustained blunt trauma to the chest that caused injury to the fibrous skeleton of the heart. The mitral and tricuspid valves and their annuli were lacerated, the aortic annulus was separated from the ventricular septum, and the ventricular septum was disrupted; however, with surgical management, the patient survived.     

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.     

Development of aortic and mitral valve continuity in the human embryonic heart

The anatomic relationship of the aortic and mitral valves is a useful landmark in assessing congenital heart malformations. The atrioventricular and semilunar valve regions originate in widely separated parts of the early embryonic heart tube, and the process by which the normal fibrous continuity between the aortic and mitral valves is acquired has not been clearly defined. The development of the aortic and mitral valve relationship was studied in normal human embryos in the Carnegie Embryological Collection, and specimens of Carnegie stages 13, 15, 17, 19, and 23, prepared as serial histologic sections cut in the sagittal plane, were selected for reconstruction. In stage 13, the atrioventricular valve area is separated from the semilunar valve area by the large bend between the atrioventricular and outflow-tract components of the single lumen heart tube created by the left interventricular sulcus. In stages 15 and 17, the aortic valve rotates into a position near the atrioventricular valves with development of four chambers and a double circulation. In stage 19, there is fusion of aortic and mitral endocardial cushion material along the endocardial surface of the interventricular flange, and this relationship is maintained in subsequent stages. Determination of three-dimensional Cartesian coordinates of the midpoints of valve positions shows that, while there is growth of intervalvular distances up to stage 17, the aortic to mitral distance is essentially unchanged thereafter. During the period studied, the left ventricle increases in length over threefold. The relative lack of growth in the saddle-shaped fold between the atrioventricular and outflow tract components of the heart, contrasting with the rapid growth of the outwardly convex components of most of the atrial and ventricular walls, may be attributed to the different mechanical properties of the two configurations. It is postulated that the pathogenesis of congenital heart malformations, which characteristically have failure of development of aortic and mitral valve continuity, may involve abnormalities of rotation of the aortic region or malpositioning of the fold in the heart tube.     

Tomographic PIV in a model of the left ventricle: 3D flow past biological and mechanical heart valves

Left ventricular flow is intrinsically complex, three-dimensional and unsteady. Its features are susceptible to cardiovascular pathology and treatment, in particular to surgical interventions involving the valves (mitral valve replacement). To improve our understanding of intraventricular fluid mechanics and the impact of various types of prosthetic valves thereon, we have developed a custom-designed versatile left ventricular phantom with anatomically realistic moving left ventricular membrane. A biological, a tilting disc and a bileaflet valve (in two different orientations) were mounted in the mitral position and tested under the same settings. To investigate 3D flow within the phantom, a four-view tomographic particle image velocimetry setup has been implemented. The results compare side-by-side the evolution of the 3D flow topology, vortical structures and kinetic energy in the left ventricle domain during the cardiac cycle. Except for the tilting disc valve, all tested prosthetic valves induced a crossed flow path, where the outflow crosses the inflow path, passing under the mitral valve. The biological valve shows a strong jet with a peak velocity about twice as high compared to all mechanical heart valves, which makes it easier to penetrate deeply into the cavity. Accordingly, the peak kinetic energy in the left ventricle in case of the biological valve is about four times higher than the mechanical heart valves. We conclude that the tomographic particle imaging velocimetry setup provides a useful ground truth measurement of flow features and allows a comparison of the effects of different valve types on left ventricular flow patterns.     

Velocity and turbulence measurements past mitral valve prostheses in a model left ventricle

Thrombogenesis and hemolysis have both been linked to the flow dynamics past heart valve prostheses. To learn more about the particular flow dynamics past mitral valve prostheses in the left ventricle under controlled experimental conditions, an in vitro study was performed. The experimental methods included velocity and turbulent shear stress measurements past caged-ball, tilting disc, bileaflet, and polyurethane trileaflet mitral valves in an acrylic rigid model of the left ventricle using laser Doppler anemometry. The results indicate that all four prosthetic heart valves studied create at least mildly disturbed flow fields. The effect of the left ventricular geometry on the flow development is to produce a stabilizing vortex which engulfs the entire left ventricular cavity, depending on the orientation of the valve. The measured turbulent shear stress magnitudes for all four valves did not exceed the reported value for hemolytic damage. However, the measured turbulent shear stresses were near or exceeded the critical shear stress reported in the literature for platelet lysis, a known precursor to thrombus formation.     

Meltrin beta expressed in cardiac neural crest cells is required for ventricular septum formation of the heart

The heart is divided into four chambers by membranous septa and valves. Although evidence suggests that formation of the membranous septa requires migration of neural crest cells into the developing heart, the functional significance of these neural crest cells in the development of the endocardial cushion, an embryonic tissue that gives rise to the membranous appendages, is largely unknown. Mice defective in the protease region of Meltrin beta/ADAM19 show ventricular septal defects and defects in valve formation. In this study, by expressing Meltrin beta in either endothelial or neural crest cell lineages, we showed that Meltrin beta expressed in neural crest cells but not in endothelial cells was required for formation of the ventricular septum and valves. Although Meltrin beta-deficient neural crest cells migrated into the heart normally, they could not properly fuse the right and left ridges of the cushion tissues in the proximal outflow tract (OT), and this led to defects in the assembly of the OT and AV cushions forming the ventricular septum. These results genetically demonstrated a critical role of cardiac neural crest cells expressing Meltrin beta in triggering fusion of the proximal OT cushions and in formation of the ventricular septum.     

Two-dimensional echocardiography in the diagnosis of unusual left atrial myxomas

In two patients with atypical myxomas of the left atrium, two-dimensional echocardiography furnished valuable diagnostic information. In one patient, who had previously developed an embolism at the right brachial artery, M-mode echocardiography revealed an abnormal band of echoes within the left atrium. Two-dimensional echocardiography showed a globular cluster of echoes that remained within the left atrial cavity throughout the cardiac cycle; left ventricular angiography confirmed the ultrasonic findings of an intraatrial mass. At surgery, a calcified, nonprolapsing myxoma was excised from the interatrial septum. The second patient had clinical as well as M-mode echographic features of mitral stenosis. Cardiac catheterization showed a significant gradient across the mitral valve, but the left ventriculogram was normal except for an unusual pattern of mitral regurgitation. Subsequent two-dimensional echocardiography revealed a mass of echoes that prolapsed through the mitral valve during diastole. At surgery, a left atrial myxoma was found attached to the posterior mitral annulus. Our experience indicates that two-dimensional ultrasound is superior to conventional echocardiography for detecting unusual cardiac masses.     

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.     

Use of pattern recognition to classify beef cardiovascular tissues on the basis of their trace metal compositions.

The pattern recognition procedure of discriminant analysis has been used to characterize the trace metal profiles created by the concentrations of 8 trace metals in 15 anatomic sites of beef heart tissue. Metals analyzed were copper, tin, lead, molybdenum, strontium, cesium, barium, and aluminum. Anatomic sites sampled included main pulmonary artery, aorta, mitral and tricuspid valves, left and right coronary arteries, os cordis, right atrium, left atrial appendage, crista supraventricularis, left bundle branch, free wall of the right and left ventricles, interventricular septum, and papillary muscle of the left ventricle. The striking features of the data were: (1) All specimens of the mitral valve, tricuspid valve, and os cordis were ambiguously described by their trace metal profiles; (2) the four blood vessels constituted two groups of two tissues each (aorta, main pulmonary artery; left and right coronary arteries); (3) tissues derived from ordinary and specialized myocardium were quite different from blood vessels, heart valves and os cordis. Using these profiles, 85% of the specimens analyzed were correctly classified by discriminant analysis with respect to their anatomic origin.     

Insights from in-vitro flow visualization into the mechanism of systolic anterior motion of the mitral valve in hypertrophic cardiomyopathy under steady flow conditions.

Hypertrophic obstructive cardiomyopathy is a heart disease characterized by a thickened interventricular septum which narrows the left ventricular outflow tract, and by systolic anterior motion (SAM) of the mitral valve which can contact the septum and create dynamic subaortic obstruction. The most common explanation for SAM has been the Venturi mechanism which postulates that septal hypertrophy, by narrowing the outflow tract, produces high velocities and thus low pressure between the mitral valve and the septum, causing the valve leaflets to move anteriorly. This hypothesis, however, fails to explain why SAM often begins early in systole, when outflow tract velocities are low or negligible or why it may occur in the absence of septal hypertrophy. The goal of this study was therefore to investigate an alternative hypothesis in which structural abnormalities of the papillary muscles act as a primary cause of SAM by altering valve restraint and thereby changing the geometry of the closed mitral apparatus and its relationship to the surrounding flow field. In order to test this hypothesis, an in vitro model of the left ventricle which included an explanted human mitral valve with intact chords and papillary muscle apparatus was constructed. Flow visualization was used to observe the ventricular flow field and the mitral valve geometry. Displacing the papillary muscles anteriorly and closer to each other, as observed clinically in patients with cardiomyopathy and obstruction produced SAM in the absence of septal hypertrophy. Flow could be seen impacting on the upstream (posterior) surface of the leaflets; such flow is capable of producing form drag forces which can initiate and maintain SAM.(ABSTRACT TRUNCATED AT 250 WORDS)     

A 2D finite element model of the interventricular septum under normal and abnormal loading

The interventricular septum is the structure that separates the left and right ventricles of the heart. Under normal loading conditions, it is concave to the left ventricle, but under abnormal loading the septum flattens and occasionally inverts. In the past, the septum has frequently been modelled as integral to the left ventricle with the effects of pressure from the right ventricle being ignored. Under abnormal loading, the septum has been described as behaving equivalent to a "flapping sail". There has been no consideration of structural behaviour under these conditions. A 2-D plane stress FE model of the septum was used to investigate the difference in structural behaviour of the septum during diastole between normal and abnormal loading. The biaxial stress patterns that develop are distinctively disparate. Under normal loading, the septum behaves much like a thick-walled cylinder subject to internal and external pressure, with the resulting stresses being circumferential tension and radial compression, both varying with radius. These stresses are very low throughout most of diastole. However, under abnormal loading, the septum behaves in an arch-like fashion, with high compressive stresses almost circumferential in direction, combined with radial compression. We conclude that right ventricular pressures cause bending effects in the wall of the heart, and that under abnormal loading, the compressive stresses that develop in the septum may lead to an understanding of certain, previously unexplained, pathological conditions.     

Mechanical Complications of Myocardial Infarction—Radiologic Aspects

Left ventricular aneurysm, interventricular septal defect and acute mitral valve incompetence due to papillary muscle damage are three mechanical complications which cause intractable heart failure following myocardial infarction. In each case surgical intervention can result in dramatic improvement of congestive heart failure.A hemodynamically significant left ventricular aneurysm enlarges the cardiac silhouette and frequently causes a localized protrusion as seen radiographically. Cardiac fluoroscopy will disclose an abnormal pulsation of the left ventricular border. The left ventricular angiogram establishes the diagnosis, reveals the extent of the aneurysm and may disclose a filling defect in the aneurysmal sac due to the presence of mural thrombus. Coronary arteriography shows occlusion of a major vessel, most commonly the anterior descending branch of the left coronary artery.Ischemic perforation of the interventricular septum and acute mitral incompetence due to severe papillary muscle damage both cause severe heart failure shortly after myocardial infarction. A similar pansystolic murmur accompanies both conditions, and differentiation between the two is rarely possible on the basis of the electrocardiogram or x-ray film of the chest. Ventricular cardiac catheterization and left ventricular angiocardiography are required for a correct diagnosis.     

Torsional motion of the left ventricle does not affect ventricular fluid dynamics of both foetal and adult hearts

Left ventricular torsion is caused by shortening and relaxation of the helical fibres in the myocardium, and is thought to be an optimal configuration for minimizing myocardial tissue strains. Characteristics of torsional motion has also been proposed to be markers for cardiac dysfunction. However, its effects on fluid and energy dynamics in the left ventricle have not been comprehensively investigated. To investigate this, we performed image-based flow simulations on five healthy adult porcine and two healthy human foetal left ventricles (representing two different length scales) at different degrees of torsional motions. In the adult porcine ventricles, cardiac features such as papillary muscles and mitral valves, and cardiac conditions such as myocardial infarctions, were also included to investigate the effect of twist. The results showed that, for all conditions investigated, ventricular torsional motion caused minimal changes to flow patterns, and consistently accounted for less than 2% of the energy losses, wall shear stresses, and ejection momentum energy. In contrast, physiological characteristics such as chamber size, stroke volume and heart rate had a much greater influence on flow patterns and energy dynamics. The results thus suggested that it might not be necessary to model the torsional motion to study the flow and energy dynamics in left ventricles.     

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。     

Compositional changes of human mitral valves with aging

To elucidate compositional changes of the mitral valve with aging, the authors investigated the relationships among element contents in the mitral valves. The subjects consisted of 10 men and 15 women, ranging in age from 65 to 102 yr. After the ordinary dissection, mitral valves, lower parts of the interventricular septa, and terminal crests containing the sinoatrial nodes were resected and the element contents were determined by inductively coupled plasma-atomic emission spectrometry. The interventricular septa and sinoatrial nodes were used to compare with the mitral valves. With regard to the mitral valve, it was found that extremely significant correlations were found among the contents of Ca, P, Mg, and Na, but no significant correlations were found between the contents of S and elements such as Ca, P, or Mg. Regarding the interventricular septum, it was found that an extremely significant correlation was found between P and S contents; very significant correlations were found between Ca and Mg contents and between Mg and S contents; and a significant correlation was found between P and Mg contents. However, no significant correlation was found between Ca and P contents in the interventricular septa. In the terminal crest containing the sinoatrial node, significant correlations were found among the contents of Ca, P, Mg, and S. The present study revealed that with regard to the relationships among element contents, the compositional change of the mitral valve was intermediate between those of the thoracic aorta and the interventricular septum.     

A 2D Finite Element Model of the Interventricular Septum Under Normal and Abnormal Loading

Abstract

The interventricular septum is the structure that separates the left and right ventricles of the heart. Under normal loading conditions, it is concave to the left ventricle, but under abnormal loading the septum flattens and occasionally inverts. In the past, the septum has frequently been modelled as integral to the left ventricle with the effects of pressure from the right ventricle being ignored. Under abnormal loading, the septum has been described as behaving equivalent to a “flapping sail”. There has been no consideration of structural behaviour under these conditions. A 2-D plane stress FE model of the septum was used to investigate the difference in structural behaviour of the septum during diastole between normal and abnormal loading. The biaxial stress patterns that develop are distinctively disparate. Under normal loading, the septum behaves much like a thick-walled cylinder subject to internal and external pressure, with the resulting stresses being circumferential tension and radial compression, both varying with radius. These stresses are very low throughout most of diastole. However, under abnormal loading, the septum behaves in an arch-like fashion, with high compressive stresses almost circumferential in direction, combined with radial compression. We conclude that right ventricular pressures cause bending effects in the wall of the heart, and that under abnormal loading, the compressive stresses that develop in the septum may lead to an understanding of certain, previously unexplained, pathological conditions.     

Transmural heterogeneity of diffusion anisotropy in the sheep myocardium characterized by MR diffusion tensor imaging

The orientation of MRI-measured diffusion tensor in the myocardium has been directly correlated to the tissue fiber direction and widely characterized. However, the scalar anisotropy indexes have mostly been assumed to be uniform throughout the myocardial wall. The present study examines the fractional anisotropy (FA) as a function of transmural depth and circumferential and longitudinal locations in the normal sheep cardiac left ventricle. Results indicate that FA remains relatively constant from the epicardium to the midwall and then decreases (25.7%) steadily toward the endocardium. The decrease of FA corresponds to 7.9% and 12.9% increases in the secondary and tertiary diffusion tensor diffusivities, respectively. The transmural location of the FA transition coincides with the location where myocardial fibers run exactly circumferentially. There is also a significant difference in the midwall-endocardium FA slope between the septum and the posterior or lateral left ventricular free wall. These findings are consistent with the cellular microstructure from histological studies of the myocardium and suggest a role for MR diffusion tensor imaging in characterization of not only fiber orientation but, also, other tissue parameters, such as the extracellular volume fraction.     

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。     

Mitral inertance in humans: critical factor in Doppler estimation of transvalvular pressure gradients

The pressure-velocity relationship across the normal mitral valve is approximated by the Bernoulli equation DeltaP = 1/2 rhoDeltav(2) + M. dv/dt, where DeltaP is the atrioventricular pressure difference, rho is blood density, v is transmitral flow velocity, and M is mitral inertance. Although M is indispensable in assessing transvalvular pressure differences from transmitral flow, this term is poorly understood. We measured intraoperative high-fidelity left atrial and ventricular pressures and simultaneous transmitral flow velocities by using transesophageal echocardiography in 100 beats (8 patients). We computed mean mitral inertance (M) by M = integral((DeltaP)-(1/2 x rho v(2))dt/integral(dv/dt)dt and we assessed the effect of the inertial term on the transmitral pressure-flow relation. ranged from 1.03 to 5.96 g/cm(2) (mean = 3.82 +/- 1.22 g/cm(2)). DeltaP calculated from the simplified Bernoulli equation (DeltaP = 1/2. rhov(2)) lagged behind (44 +/- 11 ms) and underestimated the actual peak pressures (2.3 +/- 1.1 mmHg). correlated with left ventricular systolic pressure (r = -0.68, P < 0.0001) and transmitral pressure gradients (r = 0.65, P < 0.0001). Because mitral inertance causes the velocity to lag significantly behind the actual pressure gradient, it needs to be considered when assessing diastolic filling and the pressure difference across normal mitral valves.     

Ventricle and outflow tract of the African lungfish Protopterus dolloi

We report a morphologic study of the heart ventricle and outflow tract of the African lungfish Protopterus dolloi. The ventricle is saccular and appears attached to the anterior pericardial wall by a thick tendon. An incomplete septum divides the ventricle into two chambers. Both the free ventricular wall and the incomplete ventricular septum are entirely trabeculated. Only a thin rim of myocardium separates the trabecular system from the subepicardial space. The outflow tract consists of proximal, middle, and distal portions, separated by two flexures, proximal and distal. The proximal outflow tract portion is endowed with a layer of compact, well-vascularized myocardium. This portion is homologous to the conus arteriosus observed in the heart of most vertebrates. The middle and distal outflow tract portions are arterial-like, thus being homologous to the bulbus arteriosus. However, the separation between the muscular and arterial portions of the outflow tract is not complete in the lungfish. A thin layer of myocardium covers the arterial tissue, and a thin layer of elastic tissue underlies the conus myocardium. Two unequal ridges composed of loose connective tissue, the spiral and bulbar folds, run the length of the outflow tract. They form an incomplete division of the outflow tract, but fuse at the distal end. The two folds are covered by endocardium and contain collagen, elastin, and fibroblast-like cells. They appear to be homologous to the dextro-dorsal and sinistro-ventral ridges observed during the development of the avian and mammalian heart. Two to three rows of vestigial arterial-like valves appear in the dorsal and ventral aspects of the conus. These valves are unlikely to have a functional role. The possible functional significance of the "gubernaculum cordis," the thick tendon extending between the anterior ventricular surface and the pericardium, is discussed.