The effect of vasoactive agents on the left ventricular end-systolic pressure-volume relation in closed-chest dogs.
- 1 November 1986
- journal article
- research article
- Published by Wolters Kluwer Health in Circulation
- Vol. 74 (5) , 1107-1113
- https://doi.org/10.1161/01.cir.74.5.1107
Abstract
The left ventricular end-systolic pressure-volume relation has received intense interest as a relatively load-insensitive measure of cardiac performance. In clinical studies, pharmacologic manipulation of blood pressure has been used to determine this relation. Since previous studies have shown that acute changes in the resistance and impedance of the arterial circulation influence the left ventricular-end-systolic pressure-volume relation, the use of vasoactive drugs in its determination may affect the results achieved. This study was undertaken to determine whether clinically used vasoactive drugs influence the left ventricular end-systolic pressure-volume relation. Sixteen dogs were previously instrumented with micromanometer pressure transducers and three sets of piezoelectric crystals to permit determination of left ventricular pressure and volume. The dogs were studied after autonomic blockade and sedation. End-systolic pressure-volume relations were generated by caval occlusion at control levels of blood pressure, after infusion of a vasopressor (methoxamine, n = 6; angiotensin II, n = 10), and then after infusion of nitroprusside. A composite end-systolic pressure-volume relation was also constructed with the use of control, vasopressor, and vasodilator points in each dog. Angiotensin II resulted in a leftward shift in the relation (V0 decreased from 14.32 .+-. 7.3 to 8.04 .+-. 10.4 ml, p < .05) with no significant effect on slope. Methoxamine shifted the relation to the left (V0 decreased from 13.98 .+-. 8.74 to -0.47 .+-. 12.06 ml, p < .05) and also reduced the slope (5.41 .+-. 3.09 vs 8.28 .+-. 3.94 mm Hg/ml, p < .05). Nitroprusside shifted the relation to the right (V0 increased from 13.98 .+-. 8.74 to 17.35 .+-. 11.04 ml, p < .05), but did not significantly alter the slope. The composite end-systolic pressure-volume relations in the animals given angiotensin II had a steeper slope (11.22 .+-. 4.87 mm Hg/ml, p < .05) and were shifted to the right (17.99 .+-. 8.41 ml, p < .05) compared with those generated by control caval occlusion. The composite relations in the animals given methoxamine, on the other hand, had a flatter slope (7.15 .+-. 3.13 mm Hg/ml, p < .05), with no significant difference in V0 compared with control caval occlusion. We conclude that the technique used to generate the left ventricular end-systolic pressure-volume relation influences the results that are obtained. Results obtained through the use of pharmacologic alteration of load are different than those obtained with use of rapid caval occlusion, and vary depending on the vasoactive agents used. These factors should be considered when interpreting the findings of studies on this index of cardiac performance.This publication has 12 references indexed in Scilit:
- The left ventricular dP/dtmax-end-diastolic volume relation in closed-chest dogs.Circulation Research, 1985
- Effect of regional ischemia on the left ventricular end-systolic pressure-volume relation in chronically instrumented dogsJournal of the American College of Cardiology, 1985
- The end-systolic pressure-volume relation of the ventricle: definition, modifications and clinical use.Circulation, 1981
- Dissociation of end ejection from end systole of ventricle.Japanese Heart Journal, 1981
- Left ventricular end-systolic pressure-dimension and stress-length relations in normal human subjectsThe American Journal of Cardiology, 1979
- Positive inotropic effects of methoxamine: evidence for alpha-adrenergic receptors in ventricular myocardiumAmerican Journal of Physiology-Legacy Content, 1975
- Effects of changes in preload, afterload and inotropic state on ejection and isovolumic phase measures of contractility in the conscious dogThe American Journal of Cardiology, 1975
- Mathematical interrelationship between instantaneous ventricular pressure-volume ratio and myocardial force-velocity relationAnnals of Biomedical Engineering, 1972
- Left Ventricular Time-varying Pressure/Volume Ratio in Systole as an Index of Myocardial InotropismJapanese Heart Journal, 1971
- Influence of coronary perfusion and myocardial edema on pressure-volume diagram of left ventricleAmerican Journal of Physiology-Legacy Content, 1961