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Abstract
Stable compensated left ventricular lypertrophy (LVH) was produced in dogs, often
leading to sudden death following bursts of physical activity. To investigate the
mechanism of death, we measured in 10 dogs with LVH and 12 normal dogs the effects
of stress by six-minute infusions of isoproterenol and norepinephrine. Contractility
indices of the intact left ventricle (output, minute work, external mechanical efficiency,
Vmax, and ratio of ![Math Eq]()
to isovolumic pressure) were comparable in both groups in the unstressed state and
increased similarly with stress. Mean QLV was significantly lower in LVH at rest, and increased in both groups with isoproterenol
and norepinephrine. In the unstressed dogs, LV oxygen consumption was similar in LVH
and normal, but oxygen extraction was 46 ± 3 percent in normal and 66 ± 5 percent
in LVH. With stress, O2 Consumption increased to the same level in both groups, and oxygen extraction increased
to 63 ± 5 percent in normal but did not change in LVH. Thus, the intact stable hypertrophied
myocardium shows no functional impairment during catecholamine-induced stress, but
the increased oxygen requirements of stress can be met only by an increase in coronary
flow since oxygen extraction in hypertrophy is already maximal.
to isovolumic pressure) were comparable in both groups in the unstressed state and
increased similarly with stress. Mean QLV was significantly lower in LVH at rest, and increased in both groups with isoproterenol
and norepinephrine. In the unstressed dogs, LV oxygen consumption was similar in LVH
and normal, but oxygen extraction was 46 ± 3 percent in normal and 66 ± 5 percent
in LVH. With stress, O2 Consumption increased to the same level in both groups, and oxygen extraction increased
to 63 ± 5 percent in normal but did not change in LVH. Thus, the intact stable hypertrophied
myocardium shows no functional impairment during catecholamine-induced stress, but
the increased oxygen requirements of stress can be met only by an increase in coronary
flow since oxygen extraction in hypertrophy is already maximal.To read this article in full you will need to make a payment
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Article info
Footnotes
☆Supported by research grant HL 13088-03 from the National Heart and Lung Institute, the National Institutes of Health, Department of Health, Education and Welfare.
☆☆Presented at the Thirty-fourth Annual Meeting of the Society of University Surgeons, New Orleans, La., Feb. 8–10, 1973.
Identification
Copyright
© 1973 Published by Elsevier Inc.
