What is the clinical evidence from this study?

Study design: Other. Population: Normal cardiac physiology (canine model) (n=8). Intervention: Cardiac arrest and fibrillation vs. Beating state (isovolumic contraction). Primary outcome: Left ventricular diastolic compliance and hysteresis loop area.

January 1, 1982Open Access

A comparison of left ventricular volume-pressure relations of excised perfused canine hearts in isovolumic contraction, arrest and fibrillation.

Key Result

In excised perfused canine hearts, left ventricular compliance in arrested and fibrillating states was significantly decreased compared to the beating state, with all states exhibiting hysteresis.

Structured PICO

Population

8 excised perfused canine hearts from mongrel dogs weighing 14-20.5 kg were studied to compare left ventricular volume-pressure relations across beating, arrested, and fibrillating states.

Exposure

Induction of different ventricular states (beating, potassium arrest, fibrillation) and measurement of left ventricular volume-pressure relations during inflation and deflation with saline.

Comparator

Within-subject comparison of the three ventricular states (beating vs. potassium arrest vs. fibrillation).

Outcome

Left ventricular diastolic compliance (volume-pressure relations, hysteresis, dv/dp).surrogate

Left ventricular diastolic compliance differs significantly between beating, arrested, and fibrillating states, indicating that non-beating hearts are not accurate models for beating heart stiffness.

Limitations

Left ventricular volume at 0 mmHg filling pressure was estimated rather than directly measured.
Thebesian flow into the left ventricular cavity was neglected during measurements.
Potential for myocardial edema during the experiment.
Data from excised, non-beating hearts may not fully represent intact, beating hearts.

Abstract

MARUYAMA, Y., NUNOKAWA, T., KOIWA, V., ISOYAMA, S., IKEDA, K., INO-OKA, E. and TAKISHIMA, T. A Comparison of Left Ventricular Volume-Pressure Relations of Excised Perfused Canine Hearts in Isovolumic Contraction, Arrest and Fibrillation. Tohoku J. exp. Med., 1982, 136 (2), 141-155-The purpose of the present investigation was to study the effects of various conditions such as beating, arrest and fibrillation on left ventricular (LV) diastolic compliance. In coronary-arterially perfused canine isolated hearts, LV volume-pressure (v-p) relations for both inflation and deflation were obtained by infusing and withdrawing a saline. The v-p curves of inflation and deflation were both sigmoidal, but the resultant v-p relations for deflation produced a shift to the left of inflation curves, showing hysteresis between inflation and deflation in three ventricular states. The effect of arrest or fibrillation, especially of fibrillation, on LV distensibility was discernible, and the resultant v-p relations produced a marked shift to the right, showing an apparent decrease in LV volume (LVv) at a given filling pressure. It was concluded that it is very questionable to identify the stiffness of the beating heart with the non-beating heart.

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