Biomedical subjects

B M Minczak

Publications and source records attributed to B M Minczak.

3 recordsLinked to original sources

PubMed1990

Pericardial effects of diastolic ventricular interaction during development.

The effects of the pericardium on myocardial diastolic ventricular interaction during early development were determined in vitro using hearts excised from eight preterm (109 +/- 0.106 SE d gestation; term = 147 d) and eight newborn (2.3 +/- 0.30 SE d postnatal age) lambs. The lamb hearts were excised with the pericardium intact and immersed in a cold cardioplegic solution. Subsequently, very compliant balloon catheters were inserted into the right and left ventricles retrograde through the pulmonary artery and aorta respectively. Before and after the removal of the pericardium, the changes in left ventricular pressure or volume caused by increasing right ventricular pressure or volume were measured. Computerized analysis of the pressure and volume recordings yielded pressure and volume transfer functions that quantified ventricular interaction. The pressure transfer functions (left ventricular pressure/right ventricular pressure) both with and without the pericardium intact were 0.297 +/- 0.010 SE and 0.140 +/- 0.005 SE, respectively, for the preterms and 0.650 +/- 0.033 SE and 0.301 +/- 0.031 SE for the newborns. The volume transfer functions (left ventricular volume/right ventricular volume) with and without the pericardium were 0.320 +/- 0.04 SE and 0.150 +/- 0.024 SE, respectively, for the preterm and 0.514 +/- 0.052 SE and 0.233 +/- 0.027 SE for the newborns. These data demonstrate that 1) the pericardium increases ventricular interaction in both preterm and newborn lambs and 2) the relative percentage increase is similar for both age groups and not age dependent. Furthermore, these findings suggest that the increase in ventricular interaction due to the presence of the pericardium is mediated by the relative compliances of the free walls, septum, and pericardium.

Animals↗

PubMed1988

Developmental changes in diastolic ventricular interaction.

Developmental changes in the myocardial diastolic ventricular interaction of hearts excised from 12 preterm (126 +/- 0.8 SE days gestation; term = 147 days) and eight newborn (2.5 +/- 0.2 SE days postnatal age) lambs were evaluated in vitro. The excised hearts were immersed in a cold cardioplegic solution during which time compliant balloon catheters were inserted into the right and left ventricles through the pulmonary artery and aorta, respectively. The catheters were alternately connected to an infusion pump and appropriate transducers in order to obtain simultaneous biventricular pressure and volume measurements as the volume of each ventricle was varied. Computerized analysis of the pressure and volume recording was used to determine right and left ventricular free wall compliance, ventricular septal compliance, and pressure and volume transfer functions. Ventricular septal compliance was significantly less than the free wall compliances within both groups. Ventricular septal compliance (p less than 0.05) and transfer functions (p less than 0.05) in the preterm were significantly lower than in the newborn. No significant differences in ventricular free wall compliances were found between or within age groups. These findings demonstrate an increase in ventricular coupling and functional interaction with development, potentially attributable to an increase in septal compliance with development.

Animals↗

PubMedDate not supplied

Contribution of each ventricular wall to ventricular interdependence.

The influences of pressure and volume changes in one ventricle on the other ventricle may be determined from the relative compliances of the ventricular free walls and the interventricular septum. If this is correct, then disease states which alter regional compliances should influence the diastolic mechanical coupling between the ventricles. To examine this hypothesis, the hearts of 15 canine dogs were removed and placed in cool cardioplegic solution. Balloons were inserted into each ventricle and the right and left ventricular pressure (delta Pr, delta Pl) and volume (delta Vr, delta Vl) changes caused by changing the pressure and volume of the other ventricle were recorded. Acute changes in right ventricular free wall (N = 5), septal (N = 5), and left ventricular free wall (N = 5) compliances were induced by glutaraldehyde injections. After injecting glutaraldehyde into the right coronary artery, delta Pl/delta Vr, delta Vl/delta Vr, delta Pr/delta Pl, and delta Pr/delta Vl increased significantly (P less than 0.05). After septal artery injection, pressure and volume transfer between the ventricles was significantly depressed. After left coronary artery injection, delta Pl/delta Pr, delta Pl/delta Vr, delta Pr/delta Vl, and delta Vr/delta Vl increased significantly (P less than 0.05). Thus, selective alterations in the mechanical coupling between the ventricles occurred following changes in right ventricular, septal, and left ventricular free wall compliances. Such changes may be important in diseases which primarily affect one side of the heart.

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