Basal metabolism adds a significant offset to unloaded myocardial oxygen consumption per minute.

Author:

Harasawa Y1,de Tombe P P1,Sheriff D D1,Hunter W C1

Affiliation:

1. Department of Biomedical Engineering, School of Medicine, Johns Hopkins University, Baltimore, Md.

Abstract

Myocardial oxygen consumption (MVO2) includes components for 1) mechanical energy generation, 2) activation, and 3) basal metabolism. Whereas the first two components are expected to increase in proportion with heart rate, a significant basal level of metabolism would consume oxygen even if the heart rate were zero. Contrary to this expectation, however, a previous study reported that, during unloaded beats, MVO2 per beat (which includes basal metabolism) was independent of heart rate. Accordingly, unloaded MVO2 per minute would extrapolate to zero at zero heart rate; this result is unexpected considering basal metabolism. To resolve this inconsistency, we varied heart rate over a wide range after inducing atrioventricular block in eight isolated cross-circulated canine hearts that contracted isovolumically. We examined whether a term representing rate-independent basal metabolism was needed to describe MVO2 per minute. Mechanical energy generated by the left ventricle was evaluated from the pressure-volume area, which was altered by changing isovolumic ventricular volume over at least five levels at each heart rate. Contractility, evaluated by the slope of the end-systolic pressure-volume relation, did not vary significantly with heart rate in this study. In contrast to the previous report, unloaded MVO2 per beat (i.e., MVO2 extrapolated to a pressure-volume area of zero) was not constant but fell monotonically with increases in heart rate in every heart. We considered that this trend was caused by a significant rate-independent basal level of MVO2 per minute. Multiple linear regression analysis confirmed that this rate-independent basal term differed significantly from zero in seven of the eight hearts studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Publisher

Ovid Technologies (Wolters Kluwer Health)

Subject

Cardiology and Cardiovascular Medicine,Physiology

Reference39 articles.

1. Control of myocardial oxygen consumption

2. Cardiac energetics.

3. Sagawa K Suga H Maughan L Sunagawa K: Energetics of the heart in Cardiac Contraction and the Pressure-Volume Relationship. New York Oxford University Press Inc 1988 pp 171-231

4. Ventricular energetics

5. Loiselle DS: Cardiac basal and activation metabolism in Jacob R Just H Holubarsch C (eds): Cardiac Energetics: Basic Mechanisms and Clinical Implications. Darmstadt FRG Steinkopif Verlag 1987 pp 37-50

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