Age-related characteristics of the distribution and attachment of chordae tendineae to the valves of the human heart

In 50 cardiac preparations of persons of various age (children, teenagers, adolescents, persons of mature and elderly age) distribution of various branches of the tendinous chordae (basic, marginal, commissural, rough zone) and level of their fixation to the ventricular surface of the right and left cusps of the atrioventricular valves have been studied. The tendinous chordae in direction from the apex of the papillary muscles towards the cusps of the atrioventricular valves are divided into the branches of the 2d--9th orders. Total quantity increase of the tendinous chordae is noted in the mature age, especially those of the 1st order in the left ventricle, and their decrease in the elderly age with an increase of the chordae of the 4th, 5th and 6th orders. Single chordae of the 8th and 9th orders can be found in elderly persons. Certain age specificities are revealed in fixation of various tendinous chordae to the cusps of the atrioventricular valves; they are surely connected with functional peculiarities of their different zones, that ensure air-tightness of the atrioventricular openings. There are quantitative differences of the tendinous chordae, fixed to certain cusps of the left (anterior) and right (anterior, posterior) atrioventricular valves; this is evidently connected with the role of the cusps mentioned in the mechanism of the valves closing.     

Sources of vascularization of the interventricular septum and septal papillary muscles in various types of blood supply in humans]

Using the preparation method, roentgenoangiography by means of contrast lead mass and polychromic injection of the coronary vessels, vascularization of the interventricular septum (IVS) and the septal papillary muscles (SPM) has been studied on 49 preparations of human hearts (age 19-89) The data are presented on distribution pattern of the IVS and SPM of the coronary arteries branches at various types of the cardiac blood supply. Angioarchitectonics of the IVS is described along its whole length. Topographic peculiarities of the SPM blood supply on dependence of their position on the IVS are noted.     

Study of the anatomy of the living human heart using echocardiography

For studying anatomy of the alive human heart, a new method of ultrasonic echography has been used. With its assistance it is possible to see all the cardiac chambers, interventricular and interatrial septa, tricuspidal and mitral valves, their chordae, papillary muscles, myocardium and pericardium. Not only their statics, but also their dynamics are investigated, when the heart contracts and its valves make movements. Owing to this, possibilities for studying cardiac anatomy in the alive people.     

Structure and protein composition of sites of papillary muscle attachment to chordae tendineae in avian hearts

Summary Most cardiac myocytes transmit force across fasciae adherentes, specialized sites of cell-cell adhesion. However, some cardiac myocytes in papillary muscle terminate on collagenous connective tissue in the chordae tendineae. These papillary myotendinous junctions (MTJs) are specialized for force transmission from myocytes to extracellular matrix. In the present study, we compared structural molecules at papillary MTJs to those at fasciae adherentes and skeletal MTJs. By using indirect immunofluorescence, we found that papillary MTJs more closely resemble skeletal MTJs in their molecular composition in that they are enriched in talin, vinculin, integrin, and fibronectin. Zeugmatin and -actinin, both components of fasciae adherentes, are absent from papillary MTJs. Although papillary MTJs and skeletal MTJs display strong similarities in structural protein composition, ultrastructural organization of the two junctions is different. Papillary MTJs display little folding of the junctional membrane and, according to morphological criteria, more closely resemble sites of thin filament-membrane association in smooth muscle than skeletal MTJs. Thus, papillary MTJs display a combination of structural characteristics described previously in skeletal and smooth muscles but exhibit few structural features observed previously in cardiac fasciae adherentes.     

Angioarchitectonics of the auricular and atrial walls of the human heart

Preparations of 103 human hearts at various ages have been investigated. The coronary veins are injected with contrast lead mass and a successive roentgenoangiography of the preparations is performed. The sources of blood supply of the atrial and auricular walls are determined taking into account branching variants of the atrial vessels. Vascularization peculiarities of the atrii and auriculae are described at the sinistrocoronary, dextrocoronary and even variants of the atrial branches. With age the diameter, length of the main atrial and auxillary auricular branches increase, as does their convolutivness. In the atrial and auricular walls there are areas comparatively poor in blood vessels. The branching variants do not always coinside with the types of the cardiac blood supply.     

Dynamics of left ventricular wall and mitral valve mechanics--a model study

The relation between global left ventricular pumping characteristics and local cardiac muscle fiber mechanics is represented by a mathematical model of left ventricular mechanics in which the mitral valve papillary muscle system is incorporated. The wall of the left ventricle is simulated by a thick-walled cylinder. Transmural differences in fiber orientation are incorporated by changing the direction of material anisotropy across the wall. The cylinder is free to twist. The upper end of the cylinder is covered by a thin, flexible sheet, representing the base of the left ventricle. The mitral valve is incorporated in this sheet. The tips of the mitral leaflets are connected by chordae tendineae to the papillary muscles which are attached to the bottom of the cylinder. Canine cardiac cycles were simulated for various end-diastolic values of left ventricular volume (25-120 ml, control 60 ml), left atrial pressure (0-2.7 kPa, control 0.22 kPa) and aortic pressure (5-11 kPa, control 11 kPa). In this wide range of preload and afterload mechanical loading of the muscle fibers appeared to be distributed quite evenly (SD: +/- 5% of control value) over all muscular structures of the left ventricle, including the papillary muscles.     

Myoglobin content and distribution in muscle tissues of Black Sea dolphins]

Myoglobin content is found to be higher in skeletal than in cardiac muscle of Tursiops truncatus and Phocaena phocaena and much higher than that in skeletal muscles of terrestrial mammals. According to the myoglobin content muscle fibres are devided into five types: red, white and three intermediate types. Deep muscles contain more red fibres and less intermediate fibres than superficial ones. White fibres compose almost one half of all fibres of the superficial skeletal muscles of the dolphins. The role of myoglobin distribution and higher content in oxygen supply of muscular tissue is discussed in relation to the peculiarities of dolphin breathing and blood circulation.     

兔心脏左室乳头肌的形态和动脉分布

乳头肌可因缺血、纤维化或梗塞而影响其收缩功能,并产生二尖瓣关闭不全(朱清于等,1980)。致成乳头肌功能不全最常见的原因是心肌供血不足,因此研究乳头肌的动脉,具有实用意义。一些作者(Estes,1966;Farrer-Brown,1968;Ranganathan,1969等)对人心脏乳头肌动脉来源、分支分布作过研究,但关于实验动物家兔乳头肌的动脉的研究文献尚少报道。本文为了开展实验性乳头肌梗塞的研究,对兔心脏左室乳头肌的形态、动脉来源、分布类型以及口径、血管密度等进行了研究。     

Exuberant accessory mitral valve tissue with possible true parachute mitral valve: a case report

ABSTRACT: INTRODUCTION: A parachute mitral valve is defined as a unifocal attachment of mitral valve chordae tendineae independent of the number of papillary muscles. Data from the literature suggests that the valve can be distinguished on the basis of morphological features as either a parachute-like asymmetrical mitral valve or a true parachute mitral valve. A parachute-like asymmetrical mitral valve has two papillary muscles; one is elongated and located higher in the left ventricle. A true parachute mitral valve has a single papillary muscle that receives all chordae, as was present in our patient. Patients with parachute mitral valves during childhood have multilevel left-side heart obstructions, with poor outcomes without operative treatment. The finding of a parachute mitral valve in an adult patient is extremely rare, especially as an isolated lesion. In adults, the unifocal attachment of the chordae results in a slightly restricted valve opening and, more frequently, valvular regurgitation. CASE PRESENTATION: A 40-year-old Caucasian female patient was admitted to a primary care physician due to her recent symptoms of heart palpitation and chest discomfort on effort. Transthoracic echocardiography showed chordae tendineae which were elongated and formed an unusual net shape penetrating into left ventricle cavity. The parasternal short axis view of her left ventricle showed a single papillary muscle positioned on one side in the posteromedial commissure receiving all chordae. Her mitral valve orifice was slightly eccentric and the chordae were converting into a single papillary muscle. Mitral regurgitation was present and it was graded as moderate to severe. Her left atrium was enlarged. There were no signs of mitral stenosis or a subvalvular ring. She did not have a bicuspid aortic valve or coarctation of the ascending aorta. The dimensions and systolic function of her left ventricle were normal. Our patient had a normal body habitus, without signs of heart failure. Her functional status was graded as class I according to the New York Heart Association grading. CONCLUSIONS: A recently published review found that, in the last several decades, there have been only nine adult patients with parachute mitral valve disease reported, of which five had the same morphological characteristics as our patient. This case presentation should encourage doctors, especially those involved in echocardiography, to contribute their own experience, knowledge and research in parachute mitral valve disease to enrich statistical and epidemiologic databases and aid clinicians in getting acquainted with this rare disease.     

Histochemical investigations of the accumulation of lipids in heart papillary muscle

Synopsis The lipid composition and fatty change of the papillary muscle, arterioles and chordae tendineae of the left cardiac ventricle of sixty-two patients who had died of various diseases in hospital were analysed qualitatively by histochemical techniques and thin-layer chromatography.The histochemical techniques revealed considerable differences in the fatty change of the myocardium, arterioles and chordae tendineae. The myocardial change seems to be due solely to accumulation of triglycerides. The fatty change in the chordae tendineae appears to be the result mainly of accumulation of cholesterol esters and, to some extent, of free fatty acids. The arteriolar fatty change arises mainly from accumulation of cholesterol esters and some triglycerides. The myocardial and arteriolar fatty change is greatest at the tip of the papillary muscle.The results of thin-layer chromatography showed that the lipid composition of the papillary muscle was qualitatively highly constant. The triglycerides and free fatty acid content varied.The osmium tetroxide--naphthylamine technique, which indicates phospholipids, stained the cardiac and arteriolar muscle fibres uniformly. No focal staining, suggestive of fatty change, was noted.All three tissue sites studied reacted with Baker's acid Haematein test. Staining was focal and clearly associated with fatty change. The results observed suggested that Baker's acid Haematein test is not specific for phospholipids, but it may stain neutral fats and cholesterol esters whenever large amounts of these are present in a tissue.     

Simple experiments to understand the ionic origins and characteristics of the ventricular cardiac action potential

Electrophysiological experiments are helpful for students to understand the role of electrical activity in heart function. Papillary muscle, which belongs to the ventricle, offers the advantage of being easily studied using glass microelectrodes. In addition, there is commercially available software that simulates ventricular electrical activity and can help overcome some difficulties, such as voltage clamp experiments, which need expensive apparatus when used for studies on living preparations. Here, we present a class practical session that is taken by undergraduate students at our University. In the first part of this class, students record action potentials from papillary muscles with the use of glass microelectrodes, and they change extracellular conditions to study the ionic basis of the action potential. In the second part of the class, students simulate action potentials using the Oxsoft Heart model (v. 4.0) and model their previous experiments on papillary muscle to quantify the effects. In particular, the model is very helpful in promoting understanding of the effect that extracellular potassium has on cardiac action potential by simulating voltage clamp experiments. This twin approach of papillary muscle experiments and computer modeling leads to a good understanding of the functioning of the action potential and can help introduce discussion of some abnormal cardiac functioning.     

Finite element analysis of the mitral apparatus: annulus shape effect and chordal force distribution

This study presents a three-dimensional finite element model of the mitral apparatus using a hyperelastic transversely isotropic material model for the leaflets. The objectives of this study are to illustrate the effects of the annulus shape on the chordal force distribution and on the mitral valve response during systole, to investigate the role of the anterior secondary (strut) chordae and to study the influence of thickness of the leaflets on the leaflets stresses. Hence, analyses are conducted with a moving and fixed saddle shaped annulus and with and without anterior secondary chordae. We found that the tension in the secondary chordae represents 31% of the load carried by the papillary muscles. When removing the anterior secondary chordae, the tension in the primary anterior chordae is almost doubled, the displacement of the anterior leaflet toward the left atrium is also increased. The moving annulus configuration with an increasing annulus saddle height does not give significant changes in the chordal force distribution and in the leaflet stress compared to the fixed annulus. The results also show that the maximum principle stresses in the anterior leaflet are carried by the collagen fibers. The stresses calculated in the leaflets are very sensitive to the thickness employed.     

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.     

Fibrous framework of human skeletal muscles, fasciae and tendons

By means of scanning and transmissive electron microscopy, the construction of the fibrous framework of the human skeletal muscles, fasciae and tendons has been investigated and its morphofunctional analysis has been performed. The fibrous framework of the endomysium is presented as a complexly organized system of anastomosing fibers of the connective tissue, forming a net-like construction. The fibrous structures of the framework are united into a whole construction by connecting fibers and fibrils. Different types of structural interconnection of collagenous fibers with sarcolemma are revealed. The structure of the fibrous framework both in different muscles and within one muscle has certain peculiarities. The main constructive element of the fascial fibrous framework make large anastomosing collagenous fibers, their architectonics is stabilized by connective fibers and fibrils. The construction of the tendinous fibrous framework is characterized by a pronounced anisotropia of the largest collagenous fibers and a developed network of connective structures both on the surface and inside the collagenous fibers. Structural mechanisms, interconnecting muscles and tendons, are demonstrated. Presence of anastomoses between the fibrils in the composition of the collagenous fibers in the fascia and Achilles tendon are stated. Together with the peculiarities existing, the general principle of the structural organization of the fibrous framework of the muscle system is the net-like constructure dependent on presence of anastomoses and elements of the connective system between the fibrous structures. Depending on the organ's function, the construction of the network acquires certain specific morphological forms.     

Morphologic aspects of local blood flow regulation in the myocardium

In 67 preparations of the human hearts at the first and second periods of mature age, spatial interrelations between blood vessels and cardiac muscle fibers in the ventricle myocardium have been studied. All the elements of the myocardial blood bed are oriented under a certain angle in relation to the cardiac muscle fibers. Regular arrangement of the arteries and sinusoid dilated veins under endocardium on the top of the papillary muscles and in the muscular trabecules is demonstrated. As proves the mathematical model, the slope orientation of the blood bed elements towards the cardiac muscle fibers ensures and adequate realization of the external influence of the contractile cardiomyocytes to the successive movement of blood along the intramural myocardial vessels. From morphological positions, a conclusion on the mechanism of the intracavitary pressure effect on blood movement along the intramural veins of the ventricular myocardium is argued. A conclusion is made on the leading role of the extravascular factors (intramyocardial and intercavitary pressure) in the local regulation of the blood stream in the myocardium and in development of working cardiac hyperemia.     

Features of the structure of arteries of the lower extremities in man

A comparative investigation has been performed on structural peculiarities of muscle arteries having various caliber in the lower extremities and in the anterior thoracic wall (section material, 40 observations). An essential predominance of the muscle tunic thickness and deterioration of blood supply has been stated in the arterial wall and in the distal parts of the lower extremities. The structural peculiarities revealed in the arteries of the extremities are connected with functional conditions of blood supply in the zone at the vertical position of the human body (orthostatic arterial hypertension).     

Role of endothelial cells in modulation of contractility induced by hexarelin in rat ventricle.

The synthetic growth hormone (GH) secretagogue hexarelin has important cardiac effects, that include a reduction of dysfunction in ischemic-reperfused hearts from GH-deficient rats after a chronic treatment and an increase of ejection fraction in acutely treated men. To investigate the mechanisms of its cardiac activity, we studied the effects of hexarelin (1-10 microM) on contractility of rat papillary muscles. We observed, in hexarelin treated papillary muscles, an improved recovery of contractility after anoxia. Hexarelin induced time- and frequency-dependent inotropic effects on papillary muscle. These effects were a transient increase in contractile force, abolished by propranolol (0.2 microM), followed by a reduction at low (60-240/min), but not at high (400-600/min) beating frequencies. The typical negative force-frequency relationship present in rat papillary muscles was therefore modified, and a minor increase in diastolic tension occurred after a sudden increase in stimulus frequency. Blockade of NO synthesis with 1 mM L-NAME, partially altered the response to hexarelin. MK-677 (1 microM), a non peptidyl GH secretagogue, reduced contractility, but did not alter the force-frequency relationship. The remaining effects of hexarelin were absent in papillary muscles pre-treated with indomethacin (1 microM), or after removal of endocardial endothelium with 0.5% triton X-100. The release of the prostacyclin metabolite 6-keto-PGF1alpha was increased during reoxygenation after a period of anoxia in hexarelin treated papillary muscles. Hexarelin had no significant effect on calcium transients and on I(Ca) measured in isolated ventricular cells. These findings suggest that the effects of hexarelin are mainly due to endothelium-released PGI2.     

Changes in the contractile material of human skeletal muscle following tendinous injury.

The most marked changes in the human muscle following tendinous injury can be observed in the contractile components. There is a widening of the Z-membrane, dispersion of the sarcomers, a break in their continuity, and detached bundles of myofibrils are found in the sarcoplasm. A change occurs also in the proportion of different fibre types of the muscles, in the muscle with tendinous injury a predominance of type II fibre becoming apparent. Among the proteins of myofibrils a product of disintegration of a molecular weight of 31 000 can be consequently demonstrated, and in some muscles products of disintegration with a molecular weight between 90 000 and 58,000 arise.     

Comparative anatomical characteristics of the histological structure of the arteries at the base of the brain in various mammalian orders and species]

In 30 mammalian species specific peculiarities of the arterial structure has been revealed and their dependence on the type of the brain blood supply has been demonstrated. The architectonics of the blood supply sources is correlated with the structure of the wall in the arteries, immediately participating in dumping the blood stream during its transport to the brain.     

Capillarization of the myocardium of the yak

Organometric and histometric characteristics of various parts of the heart have been performed in the yak, a permanent inhabitant at altitudes of 3,000-5,000 m above the sea level. Forty hearts of mature animals have been studied. Morphometric investigations of capillaries in the muscle fibers have been carried out in the atrial walls, in the right and left auriculae. in the ventricles and in the papillary muscles. The data are presented for each cardiac part: they describe diameters, density and volume of the capillary network and muscle fibers. In order to estimate the degree of capillarization of the cardiac muscle tissue, a new parameter is suggested to be used, when analyzing the morphometric data. It characterizes ratio of capillaries volume. According to the criterion given, a significant difference is stated between the degree of capillarization in the myocardium of the right and left ventricles. We suppose that this adequately reflects an increased loading experienced by the right cardiac parts under a long-lasting effect of altitude factors.