Effects of hemodynamic alterations on wall motion in the canine right ventricle.

Regional right ventricular (RV) wall motion was analyzed in six closed-chest, anesthetized, paced dogs by measuring distances between chronically implanted radiopaque markers on RV free wall and septum. Normally, contraction started in the sinus region 25 ms before conus region. Highest velocities of shortening occurred in the conus region (2.

Effect of endurance training on myocardial myosin adenosine triphosphatase activity of the dog.

Endurance exercise training has been found to enhance the functional capacity of the myocardium in several animal models. The sub-cellular phenomena accompanying the augmented function are yet to be explained. The present study sought to determine if the myosin ATPase activity of cardiac muscle increased as a result of endurance conditioning.

Computer analysis of left ventricular dynamic geometry in man.

Analysis of left ventricular performance in 20 normal patients was undertaken using biplane cineangiography and a semiautomatic computer image processing system. The analysis included evaluation of volumes, ejection fraction, regional shortening, patterns of ejection and filling and, when simultaneous left ventricular pressure was recorded stroke work, stroke power, wall stress and internal myocardial work. All of these data were calculated from digitized images stored permanently on digital magnetic tape, and can be reproduced without reanalysis of the cine film.

Normal cardiac myosin ATPase and mechanics in pressure overload with digitalis treatment.

Cardiac muscle myosin ATPase activity is depressed and contractile function impaired when the heart is subjected to a chronic pressure overload. Administering digitalis in the presence of chronic pressure overload significantly attenuates the decline in mechanical function. The current study sought to determine if the cardiac muscle myosin ATPase activity of cats treated with digitalis in the presence of pressure overload remains normal in parallel with the mechanical function.

Effect of force environment on regional pulmonary displacements and volumes in dogs.

Regional displacements of lung parenchyma due to respiratory movements at 1 G and 7 Gy were studied in anesthetized dogs in the left decubitus position in a water-filled respirator that provided control of respiratory volumes and rate and minimized inertial shifts in position and shape of the thorax and abdominal contents and related effects on the lungs. Inspiratory movements at 1 G were relatively uniform, although regional volume increased more in the nondependent (right) lung than in the dependent (left) lung. Regional functional residual capacity (FRC) increased in the nondependent lung and decreased in the dependent lung during exposures to 7 Gy.

A heart model for understanding three-deminsional cardiac anatomy.

A simple procedure for making cardiac casts has been described. These casts aid in the understainging of the special relationships of the ventricles, valves and coronary arteries as they appear at the time of cardiac angiography.

Recuperative potential of cardiac muscle following relief of pressure overload hypertrophy and right ventricular failure in the cat.

This study examined the recuperative potential of cat hearts subjected to experimental right ventricular pressure overload (for a 10- to 14-day period) which provoked hypertrophy with and without congestive heart failure. Five groups of cats were studied: normal controls; one group with 70% pulmonary artery constriction which produced right ventricular hypertrophy (RVH); one group with an 87% constriction which also produced right ventricular hypertrophy but with congestive heart failure (CHF); and two groups which had been similarly subjected to pressure overload but which had been allowed a recovery period of 30 days after relief of the pressure overload. Both the 70% and 87% pulmonic constrictions were associated with extensive right ventricular hypertrophy, depression of myocardial contractile function, and severe redlction of cardiac norepinephrine stores (normal, 1.

Left ventricular effects on right ventricular developed pressure.

The possibility that left ventricular (LV) performance might affect right ventricular (RV) function through the myocardium was examined by using isolated, flow-perfused, paced rabbit hearts beating isovolumically. Reducing LV volume from its optimal volume to zero caused a 5.7% decrease (N = 10, P less than 0.

Mechanism of production of cardiac conduction abnormalities due to coronary arteriography in dogs.

Left coronary arteriography and left coronary artery injections of Tyrode's solution and glucose solutions were performed in 12 anesthetized dogs. The contrast medium was found to prolong the conduction time through the AV junctional tissue and through the most distal part of the conduction network as verified by His-bundle electrogram and by surface ECG (lead II). The results indicate that for evaluation of the effects on conductivity of various media, it is most reliable to measure the altered conduction velocity in the AV nodal region.

Myocardial interaction between the ventricles.

The myocardial interaction between the ventricles was studied using isolated, flow-perfused, paced rabbit hearts beating isovolumically. In general, increasing left ventricular (LV) volume increased right ventricular (RV) diastolic and developed pressures. In particular, with a peak RV volume (RVV), increasing LV volume (LVV) from zero to two-thirds of its peak volume increase RV diastolic pressure by 1.

Cardiac volume measurement errors.

Measurements of cardiac volumes based on biplane radiographic data exhibit a cyclical variation as the heart is rotated with respect to the radiologic instrumentation. This study develops a theoretical basis for evaluating the measurement errors due to orientation, that explains the cyclical variation. Since this type of measurement error is always one of overestimation, better accuracy will be obtained if several views are performed at varying orientations and the smallest of the resulting values is used as the measurement.

Mechanisms underlying spinal cord damage in decompression sickness.

Decompression sickness, which damaged the spinal cord, was produced in anesthetized dogs using a compression chamber. Cerebrospinal fluid pressure and several intravascular and intracardiac pressures were monitored during the course of the simulated dives. Manometric responses to forcible lung inflation and abdominal compression were measured both predive and postdive after signs of spinal cord damage were evident.

The evaluation of left ventricular function in man. A comparison of methods.

Comparisons of the sensitivities of parameters for assessing left ventricular performance in man were made in 38 patients. The parameters compared were the ejection fraction, ventriculographic contraction patterns, the left ventricular end-diastolic pressure, and the contractile indices including the contractile element velocity at 10 mm Hg (Vce 10) and maximal contractile element velocity (Vmax). The contractile indices were obtained by catheter tip manometry, utilizing developed pressure (DP) to calculate the velocity of contractile element shortening (Vce) from the formula: dp/dt divided by 32 DP.