Abstract
The ESPDR determined by pharmacologic changes in afterload has been used to assess left ventricular (LV) function in the intact animal. In order to avoid alteration of autonomic cardiac tone and thus, myocardial contractility induced by pharmacologic alterations of LV afterload, we used balloon occlusion of the inferior vena cava (IVC) to decrease LV preload and measure the ESPDR. Eight puppies 6-8 weeks old weighing 2.9±0.8 kg, were instrumented with a catheter in the descending aorta and a 1.5 cm balloon occlusion catheter in the IVC. LV end systolic diameter was measured with M-mode echo. Five-second occlusion of the IVC resulted in a fall of the end-systolic pressure from 93.9±8.0 mmHg to 63.7±10.7 mmHg, with no significant change in the heart rate (191±32, 193±35 BPM). The ESPDR was linear (r=0.96±0.01), with a slope (Ees) of 98.5±34.1 mmHg/cm and a diameter intercept -0.02±0.31 cm. Administration of propranolol (0.1 mg/kg) significantly decreased Ees (64.8±12.6, p < 0.05). In puppies, preload alteration by balloon occlusion yields ESPDR eliminating reflex changes in cardiac tone induced by pharmacologic manipulations of afterload. It demonstrates propranolol induced changes in contractility, and thus, beta-blockade should not be used routinely in assessing the ESPDR.
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Zahka, K., Phoon, C., Casale, A. et al. EFFECT OF PROPRANOLOL ON THE END-SYSTOLIC PRESSURE DIAMETER RELATIONSHIP (ESPDR) IN PUPPIES. Pediatr Res 18 (Suppl 4), 133 (1984). https://doi.org/10.1203/00006450-198404001-00242
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DOI: https://doi.org/10.1203/00006450-198404001-00242
