Mechanical interactions between four heart chambers with and without the pericardium in canine hearts.

Abstract

By using excised postmortem hearts obtained from 15 mongrel dogs with the pericardium intact, we investigated mechanical interactions between the four heart chambers from the standpoint of ventricular pressure-volume relationships. The interactions investigated were those between (1) the atrium and the ventricle, (2) the right ventricle and left ventricles, (3) the atrium and one ventricle vs. the other ventricle, and finally (4) the left and right atrium and the right ventricle vs. the left ventricle. For these purposes, we inserted compliant balloons into the four heart chambers without injuring the pericardium, i.e., we incised the base of the atria which was not covered with the pericardium. We obtained the right and/or left ventricular pressure-volume relationships under a constant pressure in three other heart chambers by changing the height of the reservoir connected to each balloon. As a result, both ventricular pressure-volume relationships were hardly affected by an increase in the atrial pressure ranging from 5 to 30 cm H2O with the pericardium removed, although the ventricle became less compliant due to an increase of the same magnitude of the opposite ventricular pressure. On the other hand, the effect of an increase in atrial pressure was distinct with the pericardium intact. Also, all mechanical interactions were enhanced dramatically with the intact pericardium. Thus, the pericardium plays an important role in these mechanical interactions, especially when the filling pressures of all heart chambers increase simultaneously. Clinically, these findings may be important to understanding ventricular functions as related to various heart disease-especially acute heart failure.

Right heart pressure does not equal pericardial pressure in the potassium chloride-arrested canine heart in situ.

“…First, we compared the pre-and post-pericardiectomy pressure-time curves graphically. Second, we analyzed the relative contribution of the pericardium to chamber pressures in both sides of the heart by selecting prepericardiectomy chamber pressures of interest: 1, 3, 5, 8, 11, and 15 mmHgintherightheartand2, 5,8,11,15,20, and 25 mm Hg in the left heart. We then computed the pressure drop caused by pericardiectomy at the volumes obtained at these prepericardiectomy pressures.…”

Effect of Pericardium on Regional Myocardial Systolic Function in Acute Ischemia.

“…In addition, when both ventricles eject blood during systole, both atria become larger due to the concomitant increase in venous return. In an in vitro study, Maruyama et al (1982) showed that atrial distention elevated left ventricular pressure at any given volume with the pericardium intact. Thus, there is a possibility that the pericardial restraint on the heart becomes welldefined at end systole in acute ischemia because of the increase in blood containing structures in the pericardial sac caused by the systolic dysfunction of the left ventricle.…”

Effects of coronary artery stenosis on left ventricular end-ejection pressure-ejected volume relationships in isolated perfused canine hearts.

“…The mechanical interactions between the left ventricle and other cardiac structures, which may be supposed to occur in vivo, are small, if any, in the present study because we removed the pericardium, the right ventricle, and a part of the right atrium (Maruyama et al 1982a). Thus, left ventricular diastolic compliance might not have been changed through the intervention study, indicating that left ventricular end-diastolic volume is constant under constant left ventricular end-diastolic pressure.…”