Pathomorphology of myocardial circulation: comparative study in increased left or right ventricle afterload.

Comparative study of pathomorphology of myocardial circulation under conditions of increased afterload of the left or right ventricles showed similar changes. All compartments of the coronary bed were plethoric, capillary blood stasis and perivascular edema, more pronounced in arterial vessels, were detected in both cases. These changes equally involved both ventricles and the ventricular septum. Significant differences consisted in local increase in the density of functioning capillaries. The increase was the maximum in hemodynamically overloaded ventricle and ventricular septum, presumably due to increase of their contractile activity. The density of functioning capillaries in the intact (vs. pressure overloaded) ventricle also increased, but to a lesser degree, which could be due to systemic neurohumoral effects. If increased afterload was complicated by the development of heart failure, circulatory disorders in the myocardium progressed. Significant increase in the density of functioning capillaries in all cardiac compartments indicated decreased vascular tone and exhaustion of coronary reserve. This was paralleled by a sharp arterial plethora in case of increased afterload of the left ventricle and sharp blood stasis in the microcirculatory bed in case of increased right ventricle afterload. Reduction of effective perfusion pressure in the presence of coronary dystonia can cause coronary insufficiency and myocardial ischemia in case of increased right ventricle afterload.

[Histochemical characteristics of adrenergic myocardial and adrenal fibers in experimental narrowing of the aorta and pulmonary artery].

Ligation of the aorta or the pulmonary trunk was the method of experimental overloading of heart ventricles. Histochemical studies indicated activation of mediator chain of the sympatho-adrenal system. Catecholamines content in the nervous plexus of the overloaded ventricle did not change but there was an increase of their content in the medullary layer of the adrenals. Thus, chromaffin cells activity increases and desympathization of the heart muscle may be an important step in pathogenesis of heart failure in acute arterial hypertension.

Role of sympathetic and parasympathetic nervous systems in heart rate regulation in cats.

The effects of atropine and beta-adrenoceptor blockers on mean HR, wave structure of the cardiac rhythm, and chronotropic reaction to noise stress were examined in cats. Atropine (0.5 mg/kg) increased the mean HR and significantly decreased the spectrum power of HF, LF, and VLF oscillations. The decrease in HF power was most pronounced, which enhanced LF/HF ratio. Propranolol (0.5 mg/kg) decreased the mean HR and slightly increased the power of HF, LF, and VLF oscillations. Atenolol (2 mg/kg) exerted similar but more pronounced effects. beta-Adrenoceptor blockers increased HF power to a greater extent than LF and VLF power, which led to a decrease in LF/HF ratio. Atropine markedly decreased the chronotropic reaction to stress. beta-Adrenoceptor blockers produced no effect on the amplitude of this reaction, but accelerated restoration of initial HR. It is established that the changes in power spectrum of HR and the phase reflex reactions in cats are mediated by parasympathetic influences; the sympathetic system is involved only in the control of mean HR, probably in response to the level of animal activity. The changes in LF/HF ratio during blockade of sympathetic and parasympathetic systems are caused by opposite influences of these systems on HF oscillations, but not by hypothetic "sympathetic" and "parasympathetic" nature of LF and HF oscillations of the heart rhythm.

Sympathoadrenal system under conditions of increased left and right ventricular afterload.

Adrenergic plexuses in the myocardium and adrenal medulla were studied histochemically under conditions of increased left or right ventricular afterload. Under conditions of high afterload not accompanied by heart failure the density of sympathetic myocardial innervation remained unchanged in the loaded ventricle, but increased in the intact ventricle. Comparison of the state of the sympathoadrenal system under conditions of increased afterload complicated or uncomplicated by heart failure revealed common prognostically unfavorable changes: sharp decrease in the density of adrenergic nerve plexuses in the ventricular myocardium and activation of adrenal chromaffin cells.

Comparative pathomorphological study of contractile myocardium under conditions of increased left and right ventricular afterload.

Structural changes in the myocardium under conditions of increased left and right ventricular afterload were studied using polarization microscopy and histological, histochemical, and stereological methods. Increased afterload not complicated by heart failure was characterized by low number of damaged cardiomyocytes (3.3-6.5%) and moderate structural changes in the ventricular myocardium (contractures of different severity). Increased afterload complicated by heart failure was characterized by high ratio of damaged cardiomyocytes (5.6-19.2%) and severe reversible (grade I and II contractures) and irreversible (grade III contractures and lump degradation of myofibrils) structural changes. Irreversible damage to most cardiomyocytes included plasmatic impregnation, which was most pronounced in the subendocardial layer of ventricles operating under conditions of increased afterload. Comparative study showed that increased left and right ventricular afterload induces similar pathomorphological changes in the contractile myocardium. Our results indicate that increased afterload to the right or left ventricle is accompanied by the development of stereotypical structural changes in the myocardium. Profound and severe disturbances can cause heart failure.

Heart rhythm disturbances during the acute period of massive pulmonary embolism.

We studied the type, incidence, and dynamics of arrhythmia during the acute phase of massive pulmonary embolism complicated or uncomplicated by cardiac insufficiency. Complicated and uncomplicated massive pulmonary embolisms were accompanied by the appearance of individual and allorhythmic ventricular extrasystoles, respectively. The rise of right ventricular pressure to 70 mm Hg was critical for the development of allorhythmia. Allorhythmia started 3-268 sec after attaining critical ventricular pressure. Heart rhythm spontaneously recovered in 100 and 78% animals with uncomplicated and complicated massive pulmonary embolism, respectively. The duration of paroxysmal allorhythmia varied from 15 sec to 15 min. Electrophysiological processes in the myocardium were normalized with progression of uncomplicated massive pulmonary embolism: the incidence of single and, in particular, allorhythmic extrasystoles decreased, and electrocardiographic parameters returned to normal.

[Leukocytic shifts following pancreatic resection with a plasma scalpel and cryodestruction]. / Leikotsitarnye sdvigi posle rezektsii podzheludochnoi zhelezy plazmennym skal'pelem i kriodestruktsii.

Two series of experiments were carried out on dogs. In the first series, blood leukocytes count was studied after resection of the pancreas using plasma scalpel. The resection caused two-phase leukocyte reaction: neutrocytosis (phase I) and leukocytosis involving mainly lymphocytes and monocytes (phase II). During the first 24 hours after the resection, a sharp increase of the leukocyte intoxication index (LII) was observed. The second series of experiments was performed using the combination of plasma scalpel and cryodestruction. The graphic curves denoted a sharp fall both in total leukocytic counts and in the different types of leukocytes which were plotted separately (neutrophils, eosinophils, etc.) This can be explained by the absence of the second (lympho-monocyte) reaction. Only a slight increase in LII occurred. These results reflect lower degree of the protection and adaptation reactions of leukocytes, this being in favor of a combination of plasma scalpel and cryodestruction during the operation.