Open chest and open pericardium affect the distribution of myocardial blood flow in the right ventricle

Abstract

We have investigated the effects of open chest and open pericardium on the distribution of myocardial blood flow assessed with the radioactive microsphere technique (15 microns). Five dogs with intact thorax served as controls (group I) and six dogs were studied after a right-sided thoracotomy and pericardiotomy (group II). Global myocardial blood flow (mean +/- S.D.) was 0.73 +/- 0.17 ml.min-1.g-1 in group I and 1.22 +/- 0.09 ml.min-1.g-1 in group II (p less than 0.05). Analysis of transmural blood flow distribution revealed that flow was 44% higher in the right and 60% higher in the left ventricular endocardial layers in the open-chest animals, whereas epicardial flow increased by 105% and 90%, respectively. As a result of the preferential blood flow to the epicardial layers of the right ventricle, the endo/epi ratio was reduced from 1.30 +/- 0.26 in group I to 0.86 +/- 0.11 in the open-chest group (p less than 0.05). Left ventricular endo/epi ratio was 1.27 +/- 0.16 and 1.06 +/- 0.11 (n.s.), respectively. External work and diastolic filling pressure of the right ventricle did not differ between the two groups and therefore cannot account for the redistribution of myocardial blood flow. It is concluded that the distribution of myocardial blood flow, particularly in the RV, is severely disturbed by thoracotomy and pericardiotomy. This is an important aspect for the planning and evaluation of studies under open-chest/open-pericardium conditions.

Right ventricular oxygen supply/demand balance in exercising dogs

“…Studies in anesthetized dogs (22,(32)(33)(34) have demonstrated that the RV oxygen extraction reserve can be mobilized to meet increased RV oxygen demand pro-duced by pacing, isoproterenol infusion, or pulmonary artery constriction. However, anesthesia, open-chest surgery, and perfusion systems may have blunted RC vasoconstrictor tone in these experiments (7,9,12,35), and, thus, yielded inappropriately high RC flow and low RV oxygen extraction values. Experiments in conscious dogs were required to ascertain that resting RV oxygen extraction reserve is, indeed, greater than that of the LV, and then to define the extent to which this reserve contributes to RV oxygen supply during exercise.…”

Impact of transcatheter aortic valve implantation or surgical aortic valve replacement on right ventricular function

“…Although reporting only very small patient groups (≤20 patients) and providing limited information on RV function (TAPSE only in one study and largely angle dependent tissue Doppler measurements in the other study), two very recent publications support the finding that TAVI—in contrast to sAVR—does not negatively affect RV function 19 20. Pericardiotomy that has been reported to result in perturbation of myocardial blood flow in the right ventricle and to negatively affect RV end diastolic pressure could be one explanation 21 22. The systemic inflammatory response due to the release of pro-inflammatory cytokines in association with cardiopulmonary bypass could be another reason for the damage of RV myocardium 23.…”

Effect of coronary artery bypass surgery on myocardial function as assessed by tissue Doppler echocardiography

“…Pericardiotomy has been reported to result in perturbation of myocardial blood flow in the right ventricle [18] and pericardiotomy negatively affects right ventricular enddiastolic pressure [19]. On cellular level, systemic inflammatory response due to the release of pro-inflammatory cytokines is a recognised feature of cardiopulmonary bypass [20].…”