Biomedical subjects

M A McDonnell

Publications and source records attributed to M A McDonnell.

3 recordsLinked to original sources

PubMed1979

Comparative effect of counterpulsation and bypass on left ventricular myocardial oxygen consumption and dynamics before and after coronary occlusion.

In this preparation counterpulsation effect was found equivalent to 42 +/- 7% of complete left ventricular bypass before, and 46 +/- 9% post-coronary occlusion. We conclude that counterpulsation is effective mainly by reducing a major determinant of myocardial oxygen consumption, i.e., afterload, whereas left ventricular bypass by reducing primarily preload results in secondary afterload reduction when peripheral resistance is unchanged. At the higher left ventricular bypass levels, reduction of myocardial oxygen consumption is far greater than during balloon counterpulsation. Acute functional loss of myocardium does not alter the effect of these assist methods regarding the reduction of myocardial oxygen consumption. Whether selection of either method for clinical application should be made only on the basis of its capability for reduction of myocardial oxygen consumption remains to be justified by conclusive demonstration of beneficial effect of reduction of myocardial oxygen consumption in the specific circulatory disorders.

Animals↗

PubMed1978

Intermittent severe mitral regurgitation.

The findings in two patients with hemodynamic evidence of intermittent severe mitral regurgitation with cyclic variation in right and left ventricular pressures are presented. Both patients had aortic and mitral valvular regurgitation of unknown etiology without definite evidence of papillary muscle dysfunction. The basis for the variation in the degree of mitral regurgitation is unclear.

Aortic Valve Insufficiency↗

PubMed1975

Comparison of clinical and hemodynamic assessment of cardiac disability.

Clinical versus hemodynamic assessment of cardiac disability was compared in 187 patients with either coronary artery or valvular disease classified using the New York Heart Association classification (excluding class IV). The following variables were analyzed during rest and exercise: arteriovenous oxygen content difference (CavO2), cardiac index (CI), pulmonary artery pressure (PAP), pulmonary artery wedge pressure (PAWP), pulmonary arteriolar resistance index (PARI) and heart rate (HR). 180 comparisons of variables were made. Hemodynamic evaluation paralleled clinical evaluation only 19 times during rest and 12 during exercise. There were 5 instances of clinical and hemodynamic distinction between class I and II, 14 between class I and III and 12 between class II and III. Correlation was best in mitral stenosis. The most useful variable was CI followed by PAP and CavO2. HR was not helpful. This study emphasizes that subjective clinical disability may not correlate with physiologic derangement in certain patients.

Adolescent↗