Abstracts of Posters Presented at the International Anesthesia Research Society; 72nd Clinical and Scientific Congress; Orlando, FL; March 7-11, 1998: Cardiovascular Anesthesia
Introduction: Etomidate (E) maintains arterial blood pressure in patients with compromised cardiac performance, however, the effects of E on specific indices of left ventricular (LV) systolic and diastolic function in vivo have not been described. We examined the actions of E on LV function in dogs with dilated cardiomyopathy produced by rapid LV pacing.
Methods: After Animal Care Committee approval, dogs (n=6) were chronically instrumented for measurement of aortic and LV pressure, +dP/dt, cardiac output (CO), and subendocardial segment length. Myocardial contractility and LV isovolumic relaxation were evaluated with preload recruitable stroke work slope (MW) and a time constant (T), respectively. Dogs were paced at 240 beats/min for 21 days after recovery from surgery. Pacing was discontinued and the experiment was performed during sinus rhythm. Hemodynamics were recorded in the conscious state (C). Anesthesia was induced with E (5 mg/kg, i.v.) and measurements were repeated after 20 min equilibration at 5, 10, and 20 mg/kg/h infusions of E. Changes between interventions were compared by ANOVA followed by Student's t-test (*P<0.05 compared to control).
Results: Heart rate, mean arterial pressure (MAP), and LV systolic and end-diastolic pressures were unchanged by E in cardiomyopathic dogs. E markedly decreased CO and increased systemic vascular resistance. E decreased +dP/dt and MW, indicating a reduction in myocardial contractility (Figure 1). E also increased T, consistent with prolonged LV isovolumic relaxation.
Discussion: The results indicate that maintenance of arterial pressure during E anesthesia occurs as a consequence of increases in SVR and is accompanied by simultaneous negative inotropic and lusitropic effects and reduced cardiac performance in dogs with LV failure.