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At least 19 recordsLinked to original sources
PubMed1975

[Compensatory-adaptive changes in the endocardium in functional overload of the heart].

In experiments on 46 dogs a structural rearrangement of the endocardium of the left atrium in the process of development of the chronic compensated cardial insufficiency was studied. Dynamics of changes, caused by hypertrophy of the subendothelial layer of the endocardium and its subsequent differentiation, which led to hyperelastosis of the endocardium, as well as hypertrophy and hyperplasia of the smooth-muscle elements of the endocardium were revealed. Analysis of the data obtained, from the functional point of view, enabled the authors to consider the described rearrangement of the endocardium as one of the mechanisms of cardiac compensation.

Acute Disease↗
PubMed1978

Starch granulomata of the endocardium.

Two cases of granuloma of the endocardium following cardic catherterisation are described. In each case the granuloma consisted essentially of macrophages associated with intracellular and extracellular starch granules, derived presumably from the glove powder used at operation. No previous cases of this condition have been found in the literature.

Adult↗
PubMed1978

Permanent cardiac pacing with electrodes of a new type of fixation in the endocardium.

To improve electrode construction the following main problems have been considered: (1) reliable initial fixing in the endocardium, and (2) reducing the area of contact surface and improving threshold values. In this article we have described three original electrodes: 1) an endocardial electrode with a multi-edged tip (contact area 28 mm2), which gives high electric field strength and low thresholds; 2) a spreading tip electrode, which was created on the basis of morphological data. The tissues grow into the spread spaces of this tip and ensure better stability (contact area 17.8 mm2); and 3) a double-screw-in electrode which differs from the other corkscrew types. The contact end (surface area--10.4 mm2) consists of two sickle-shaped hooks. The sickle handle is 0.7 mm in length which prevents further hook penetration in the wall of the heart. It was found that a multi-edged electrode and electrodes supplied with a fixation device are, in terms of energy consumption, more effective compared to electrodes with spherical or cylindrical tips of the same area of contact surface. The double-screw-in endocardial electrode has useful features: reliable fixation and a small contact surface area and, therefore, a low threshold value. Thirty-five double-screw-in electrodes were inserted into an atrial position and 28 into a ventricular position. We have not observed any displacement of such electrodes during the past two years.

Cardiac Pacing, Artificial↗
PubMed1975

The ultrastructure of the sensory end-organs (baroreceptors) in the atrial endocardium of young mini-pigs.

Light and electron microscopical studies on pig hearts have confirmed the presence in the right and the left atrial endocardium of distinct circumscribed, unencapsulated end-organs (baroreceptors) associated with 4-9 mum thick nerve fibres. The myelin sheath terminates before the entrance of the nerve into the end-organ. The regular presence of thin axon profiles containing clusters of small agranular vesicles, both around the thick nerve fibre and in the periphery of the end-organs, suggests a double innervation. The thick fibre arborizes inside an aggregate of Schwann-like cells to form a large number of terminals which are considered to be the mechano-sensitive receptors of the organ. In addition to the nervous structures and the Schwann-like cells the organs contain a varying number of connective tissue fibrils. The terminals are covered by a basement membrane but are partly or completely devoid of Schwann cell covering. Most of the space inside the terminals is occupied by tightly packed mitochondria. Glycogen granules are regularly present, sometimes abundant. SER occurs widely, frequently forming complexes with glycogen granules. These complexes may be highly organized as parallel or concentric structures, suggesting a close connection between SER and glycogen metabolism in the terminals. The terminals are regularly furnished with small protrusions containing numerous 30-100 nm clear vesicles which resemble pinocytotic vesicles. In addition, a few 80 nm dense-cored vesicles are found. The occurrence of numerous cyto-segresomes and lipofuscin-like bodies suggests a lively turnover of organelles in the terminals.

Animals↗
PubMed1978

Metastatic tumors of the endocardium: report of three cases.

Because of their apparent rarity and the tendency of clinicians to lump indicative signs and symptoms under the heading of metastatic disease, metastatic tumors of the endocardium are seldom mentioned in the literature, in the three cases presented herein, endocardial metastases were evident at autopsy. In one case of malignant melanoma, clinical evidence for endocardial involvement was present in life. This article also presents a case of endocardial involvement by Wilms' tumor and a case of endocardial involvement by hypernephroma with pulmonry tumor emboli.

Adenocarcinoma↗
PubMed1979

Time course of infarct growth toward the endocardium after coronary occlusion.

Transmembrane potentials and ultrastructure of subendocardial Purkinje and ventricular muscle fibers, isolated 1, 3, 5, 6, 14, and 24 h after coronary occlusion were investigated. Action potentials were recorded from progressively fewer layers of muscle cells as the age of the infarct increased. At 14 h little viable muscle remained. The decrease in the number of electrophysiologically viable muscle fibers correlated with structural evidence that the infarct moved with time toward the endocardial surface until only viable Purkinje fibers remained. Purkinje and surviving ventricular muscle fibers demonstrated a progressive decrease in resting potential, action potential amplitude, and Vmax and a progressive increase in action potential duration. Spontaneous diastolic depolarizations were found in Purkinje fibers only in 24-h infarcts and occasionally in cells deep to the endocardial surface, which may have been muscle cells. We hypothesize that during the first 24 h after coronary occlusion arrhythmias originate near the interface of infarcted and ischemic myocardium. As this interface moves toward the endocardium, this site of origin of arrhythmias moves with it until the Purkinje network is reached.

Animals↗
PubMed1977

Responses of canine endocardium to stimulation of the upper thoracic roots.

In each of 10 mongrel dogs anesthetized with alpha chloralose, strain-gauge arches were sutured to five epicardial and three endocardial locations. Comparisons of contractile force responses during stimulation of the left and right roots of the same segmental level revealed several differences dependent upon the particular myocardial area observed. Of the three left ventricular endocardial areas studied, the interventricular septum was the most responsive, particularly during stimulation of the right roots. The basal free wall and posterior papillary muscle were more responsive to left-root than to right-root stimulations. Epicardial responses were consistent with those previously reported. Generally, all areas responded to the greatest degree during stimulation of the second roots with the third and first next in order of effectiveness. Although stimulation of each level of preganglionic outflow activated all epicardial and endocardial segments of the myocardium, the magnitude of the changes in contractile force were highly variable dependent upon the specific level of preganglionic outflow and the location of the strain-gauge arch.

Animals↗
PubMed1977

Atrial receptors in the dog and rabbit.

1. Action potentials were recorded from slips of the cervical vagi in anaesthetized dogs and rabbits. Single functional units with atrial patterns of discharge (Paintal Type A, B and intermediate) were obtained and then attempts were made to alter (i.e. convert) their patterns of discharge. Finally the points of origin of these action potentials were located.2. Thirty unselected units were investigated in thirty dogs. Twenty-seven of these were located in the endocardium of the vein-atrial system and the ratio of the type A, type B and intermediate type receptors was 1:16:10; three units were located elsewhere in the chest. Conversion of the pattern of discharge was achieved in twenty of the twenty-seven units; conversion was achieved in the single type A unit.3. In a second series of experiments in dogs, eight Paintal Type A units were selectively studied in fifteen animals. Four of these were located in the endocardium and all were converted. The remaining four were located outside the endocardium and conversion could not be achieved in two of these. Thus in the entire investigation, the ;type A' units which could not be converted were all located at sites other than the atrial endocardium.4. In the corresponding unselected study in the rabbit, eleven units were studied in eleven animals. Nine of these units were located in the atrial endocardium and the ratio of the type A, type B and intermediate type receptors was 2:1:6. Conversion was achieved in both type A units, the sole type B unit and two of the intermediate units. One of the two units found outside the atrial endocardium was a ;type A' unit and could not be converted.5. The present investigation has shown that the atrial receptors with a Paintal Type A pattern of discharge are relatively rare in both dogs and rabbits. Conversion of the pattern of discharge is a relatively common phenomenon. Evidence for the proposition that there is one basic type of atrial receptor whose pattern of discharge is determined by its precise location in the vein-atrial system is discussed.

Action Potentials↗
PubMed1979

Endocardial alterations in myocardial infarction.

Transmural infarcts of the ventrolateral wall of canine left ventricle were produced by ligation of the ventral interventricular (anterior descending) branch of the left coronary artery. Endocardium from these infarcted hearts was sampled at sites corresponding to the infarct center and periphery, and to uninfarcted (normal) area at 24 and 48 hours after ligation, and examined by correlative scanning and transmission electron microscopy and by light microscopy. Endocardial samples from sham-ligated hearts were included as a further control. Striking alterations were observed in the endocardium that lined infarcted myocardium. There was endothelial desquamation coextensive with leukocytic invasion. Leukocytes appeared to initiate sloughing by separating the endothelial cells from their basal lamina and partially from one another. The latter cells desquamated in sheets, leaving behind a denuded basal lamina. Although altered in form, the individual endothelial cells seemed to remain largely intact. Denuded subendothelial surfaces only rarely contained thrombi. In areas where the cardiac endothelium was altered, the subjacent subendocardium, myocardium, and usually the remainder of the endocardium also showed leukocytic exudate. Samples from uninfarcted regions showed an intact, leukocyte-free endocardium, as did the sham-ligated controls. The appearance of abnormal endocardium was qualitatively similar wherever found, whether in different areas of the same heart or from one heart to another, and regardless of age of infarct. In 48-hour infarcts, almost all of the central and most of the peripheral samples exhibited the changes described. The data suggested a similar pattern for hearts with 24-hour infarcts. By locating biopsy sites in frozen cardiac sections processed for histologic staining and 201-thallium autoradiography, the electron microscopy results were shown to correlate with the intramural histopathologic topography of the infarcts. The alterations described here represent the endocardial manifestation of the inflammatory stage of transmural infarcts, known to be well developed in 1- and 2-day-old lesions.

Animals↗
PubMed1978

The role of canine superficial ventricular muscle fibers in endocardial impulse distribution.

Thin sections of canine right and left ventricular endocardium and myocardium were studied in a tissue bath to compare conduction properties of intraventricular specialized conducting tissue [Purkinje fibers (PF)], the superficial layers of subendocardial ventricular muscle (SVM), and the deeper ventricular muscle (DVM) below this level. The study was carried out because of observations that some areas of the endocardium, which are devoid of either specialized conducting tissue or of PF-VM junctions between specialized conducting tissue and ventricular muscle, conduct relatively rapidly, favoring specific orientations of propagation. Preparations containing PF, SVM, and DVM were studied electrophysiologically and histologically. A technique of stripping limited areas of endocardium was used to expose DVM in order to determine its intrinsic calculated conduction velocity. In 12 preparations, the average calculated conduction velocity in PF was 1.62 m/sec, and the average in DVM was 0.26 m/sec. The SVM conduction velocity was intermediate between the two, averaging 0.98 m/sec when propagation was parallel to SVM fiber orientation. Conduction velocity transverse to SVM fiber orientation was not significantly different from DVM conduction velocity. Histologically, the most superficial layers of VM were oriented uniformly in the direction of rapid subendocardial conduction, in contrast to DVM fibers in which orientation varied. It is concluded that the geometric arrangement of SVM fibers may provide a means for rapid subendocardial conduction and impulse distribution at a conduction velocity intermediate between PF and DVM in areas devoid of specialized conducting tissue.

Animals↗