Modified heart-lung preparation for the evaluation of systolic and diastolic coronary flow in rats

Abstract

A modified heart-lung preparation of the rat, which permits measuring systolic and diastolic coronary flow separately and enables coronary compliance to be evaluated, is described. The systemic circulation was substituted by a shunt circuit, and the elastic properties of the arterial tree were mimicked by a rubber balloon. Systolic and diastolic coronary flow was evaluated from the pulmonary and aortic flow signal. Integrated phasic pulmonary flow represented right ventricular stroke volume. Integrated phasic systolic aortic flow represented left ventricular stroke volume minus that volume flowing into the coronary arteries during systole, because the aortic flow probe had to be inserted distal to the origin of the coronary vessels. Because right and left ventricular stroke volume was identical under steady-state conditions, the difference between systolic pulmonary and systolic aortic flow resulted in systolic coronary flow. Diastolic coronary flow was measured by means of the retrograde flow through the aortic flow probe. Coronary compliance was calculated according to Frank's windkessel model from coronary resistance and from central diastolic aortic pressure, which decayed exponentially after switching out the rubber balloon and the shunt circuit. It could be shown that the proportion of systolic to diastolic coronary flow depends on coronary compliance.

In vivo characterization of rodent cyclic myocardial perfusion variation at rest and during adenosine-induced stress using cine-ASL cardiovascular magnetic resonance

“…A likely explanation for this behavior is that the vascular system of the heart has a capacitive property when submitted to pressure variations at its entry. Analogies between electrical circuits and the vascular system, such as the Windkessel model, have been often used for modeling approaches [40]. In a similar way as electric current in a capacitor submitted to voltage variations, the pressure oscillations lead to flow oscillations whose amplitude depend on the frequency of the pressure variations, here given by the heart rate.…”

The Use of Partial Fatty Acid Oxidation Inhibitors for Metabolic Therapy of Angina Pectoris and Heart Failure

“…Under conditions of an increased energy demand, the utilization of glucose can markedly increase. In an isovolumically beating heart preparation [69], the consumption of glucose can be increased up to 50% [68,70]. Although the mechanisms responsible for this shift in fuel metabolism could be related to the high adrenergic drive, it appears that this heart preparation can partially mimic the energetic status of a chronically overloaded heart.…”