CARDIOVASCULAR ENGINEERING Journal for Extracorporeal Circulation, Assist Devices,Transplantation and Artificial Organs
	Volume 2, 1997, No 2

Influence of Coronary Perfusion Pressure and Aortic Pressure on Left-Ventricular Geometry

G. Tenderich, K. M. Zhang, J. D. Schipke, M. M. Körner, N. Mirow, K. Minami, R. Körfer, G. Arnold

Abstract:
The influence of coronary perfusion and aortic pressure on hemodynamics was examined in 32 isolated, saline-perfused, isovolumetrically working rabbit hearts, paying particular attention to the wall thickness, measured by ultrasound, and the inner diameter of the left ventricle. An increase in aortic pressure of 34%, maintaining constant coronary perfusion pressure, causes an increase in left-ventricular pressure of 12% and in the maximum rate of pressure rise of 1.2%. Whereas the left-ventricular end-diastolic pressure increases by 25% and the inner diameter by 8% (systolic) and by 3.1% (diastolic), the wall thickness decreases by 4.3% (systolic) and by 2.0% (diastolic). - The heart follows the Frank-Starling mechanism. An increase in the coronary perfusion pressure of 34%, maintaining constant aortic pressure, leads to an increase in the left-ventricular pressure of 12% and in the maximum rate of pressure rise of 22.3%. If the left-ventricular end-diastolic pressure decreases by 17.3% and the inner diameter by 5% (systolic) and by 3% (diastolic), the wall thickness increases by 4% (systolic) and by 3% (diastolic) (garden-hose-effect). An alternating stepwise increase in aortic pressure and coronary perfusion pressure leads to an increase in cardiac performance through the Frank-Starling mechanism. Bringing the coronary perfusion pressure up to the level of the aortic pressure in a second step, with a decrease in left-ventricular end-diastolic pressure and inner diameter, a simultaneous increase in wall thickness initiates a renewed increase in cardiac performance. A decrease in the left-ventricular inner diameter is accompanied by a decrease in the inner volume of the ventricle. This investigation supported the assumption that an increase in coronary perfusion pressure leads to a distension of the intramural coronary vascular tree and to an increased preload of the myocardial fiber. Through the resulting inodecrease in wall thickness, the reduced left-ventricular end-diastolic pressure and the reduced inner diameter, the heart is capable of higher performance levels. The aforementioned hemodynamic effects could be an explanation for the controversially discussed Anrep-effect.

Keywords:
Anrep-effect, garden-hose-effect, hetero-homeometric autoregulation

Address for Correspondence:

Reference:
(CVE. 1997; 2 (2): 97-103)

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