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R Lolov

Publications and source records attributed to R Lolov.

At least 19 recordsLinked to original sources
PubMed1994

Location of the electrical center of ventricular depolarization in rabbits.

This is a study on the location of the ventricular depolarization center, carried out on fifteen healthy rabbits according to the method of Ritsema van Eck. It is established that the level of equivalent heart dipole coincides with the fourth or fifth intercostal space, but in some laboratory animals this level displays a lower positioning. The inference is reached that to secure correct application of Frank's lead system it is necessary to use a prompt and precision method for determination of the level in question in each individual case. Such a method has not been developed as yet. For the time being, the optimal solution of the problem could be accomplished through a lead system that is less sensitive to electrode positioning errors.

Animals↗
PubMed1994

Disorders of ventricular contractility and electrogenesis in the early stage of endotoxin shocked rabbits.

This is a report on ventricular contractility and electrogenesis disorders in rabbits, following intravenous injection of E. coli endotoxin at a dose of 2 mg.kg-1. At the 30th min, the right ventricular contractility indices (dP/dtmax)/P and [(dP/dt)/P]max had lower values, whereas end diastolic pressure (EDP), right ventricular systolic pressure (RVSP) and P(dP/dtmax) showed higher values compared to the initial ones. Most of the left ventricular contractility indices tested showed significantly lower values at the 30th and 60th min of the registration. In the scalar orthogonal ECG leads, at the 5th min an increased Qz amplitude, and at the 60th min an increased Rz amplitude, a decreased Ry amplitude, and QRS complex widening and bradicardia, were registered. In the spatial magnitude curve an increased amplitude of the main vectors of ventricular depolarization was documented. The changes in electrogenesis are interpreted first and foremost by the presence of hemodynamic disorders. The inference is reached that both left and right ventricular dysfunction have been already formed during the initial stage of endotoxin shock.

Animals↗
PubMed1990

A study of ventricular electrogenesis and contractility in acute pressure overload of the right heart ventricle.

A model of fat embolism induced acute pressure overload of rabbit right ventricle of heart is presented. A decrease in right ventricular contractility is registered as early as the first minutes after loading. Changes in spatial magnitude and polar coordinates of vectors of ventricular depolarization, and myocardial ischemia manifestations are recorded. The changes in electrogenesis described are attributed basically to ensuing development of hemodynamic disorders.

Animals↗
PubMed1989

Decreases in left ventricular contractility during endotoxin shock in rabbits.

The participation of the heart in shock syndrome formation during endotoxin shock is a problem still awaiting solution. The task undertaken is to assess the work of the left ventricle and arterial pressure in rabbits before and after endotoxin injection at a dose of 2 mg.kg-1. Heart rate is the first to reach significantly lower values--at 30 min (p less than 0.05). At 45 min, there are significant reductions in dP/dtmax (p less than 0.01), (dp/dt)/P40 (p less than 0.001), LVP (p less than 0.05), and increase in dP/dtneg (p less than 0.02). Both the systolic and diastolic blood pressures were significantly decreased at 60 min. The data obtained warrant the assumption that impaired myocardial contractility plays a part in the formation of shock syndrome in rabbits exposed to endotoxin.

Animals↗
PubMed1988

Effect of calcium blocking agent verapamil on blood pressure, ventricular contractility, parathyroid hormone, calcium and phosphorus in plasma, catecholamines, corticosterone and plasma renin activity in spontaneously hypertensive rats.

In four-month-old spontaneously hypertensive rats (SHR) the effect of a calcium blocking agent verapamil on blood pressure, ventricular contractility indices, parathyroid hormone (PTH), plasma renin activity (PRA), plasma and adrenal corticosterone content and catecholamines in hypothalamus, myocardium and adrenal gland was evaluated. Calcium and phosphorus in plasma were also determined. Verapamil treatment resulted in a significant decrease in systolic and diastolic blood pressure and a reduction in maximum left ventricular pressure. Verapamil exerted a negative inotropic effect, evaluated by a decrease in dP/dt max and dP/dt neg. PRA was elevated, calcium tended to decrease, and no changes in PTH and phosphorus were found. The hypotensive effect of verapamil in SHR was accompanied by a decrease in plasma and adrenal corticosterone content, and a fall in catecholamine concentration in adrenal glands and myocardium.

Animals↗
PubMed1986

Effect of captopril on some ventricular contractility indices in spontaneously hypertensive rats (SHR).

Two groups of SHR were treated with captopril (Squibb): the first group (1 month old)--30 mg/kg i.p. twice daily for 77 days, and the second group (8 months old)--20 mg/kg p.o. twice a day for 23 days. The recording of electrocardiogram (ECG), systolic blood pressure (SBP), diastolic blood pressure (DBP), and some isometric indices of the left-ventricular contractility indicate that in all treated animals the values of most of the parameters are considerably lowered compared to the controls. The ratio between velocity of pressure increase and intraventricular pressure/equal to 50 mmHg--(dP/dt)/ICP50/does not change significantly. It can be concluded that in SHR, captopril practically does not influence the inotropic condition of the myocardium.

Animals↗
PubMed1985

Spatial magnitude of the normal QRS-complex in the electrocardiogram of rabbits. Velocity and acceleration of the spatial magnitude.

The article describes the curves of the spatial magnitude (SM) of the normal QRS-complex in 52 rabbits, as well as of the velocity and acceleration of SM as a function of time. The X-, Y- and Z-recordings after McFee and Parungao are subjected to analogue-to-digital conversion and computer-calculation. The SM-curve consists of two and less frequently of three peaks, the third peak having the greatest amplitude and the first peak--the smallest. The three peaks are discovered at 16, 41 and 64 per cent, respectively, of the duration of the QRS-complex. The results are discussed in relation to data about other mammals and humans. The characteristic points in the curves of the recorded parameters are compared.

Animals↗
PubMed1984

Comparative study of three vectorcardiographic lead systems.

A homogeneous model of rabbit torso and physical dipole are used. A comparison is made between the corrected orthogonal vectorcardiographic lead systems after Frank, McFee-Parungao and Zao. The components X, Y, Z of the lead vectors are measured for 15 points which can be inserted in the cardiac volume under normal conditions. The modules of the lead vectors and the angles between them are calculated. The three vectorcardiographic systems are compared with respect to the ratio between the modules (X:Y:Z) and the deviations of the angles from the real value. Best orthogonality are found with the system after Frank, if the thoracic electrodes are placed precisely at the level of the so-called electrical cardiac centre. No essential differences are found between the systems after Frank and after McFee-Parungao with respect to correctedness and orthogonality.

Animals↗
PubMed1981

[Changes in electrolyte homeostasis in acute loading of the right heart].

The authors carried out experimental studies on electrolyte homeostatis of healty cats and of cats with experimental stenosis of the lung artery after venous infusion of the dextran plasma substitute Reoisodex. There was a statistically significant reduction only of the level of ionized calcium under the influence of the infusion. The authors established an increase of the level of inorganic phosphorus and of the serum bicarbonates in animals with experimental stenosis of the lung artery.

Animals↗
PubMed1979

[Electrocardiographic and histomorphological changes in the myocardium of rats with Selye's experimental hypertension].

The authors described electrocardiographic and histomorphological changes in white rats with coarctation hypertention, induced by the method of Selye. The electrocardiographic changes were manifested as prologation of preauricular-ventricular conduction time, dislocation of the intermediate part ST to the isoelectrical line, low, negative or biphasic T-wave at the initial stages of the experiment, but after the thirthieth day there was a pathologic Q-wave, a reduced voltage of the steap curves and manifested left type of ECG in the majority of the experimental animals. Histomorphological and histochemical study on thmyocardium revealed in the beginning of the experiment mainly lesion changes, but sign of myocardial hypertrophy and manifested difuse and/or focal myocardial fibrosis on the 30th to the 90th day of the experiment.

Animals↗