Abstract
Although a variety of factors, both exogeneous and endogeneous, has been known to alter the toxic action of digitalis, literatures dealing with the hemodynamic studies on the sensitivity to digitalis are scanty. Present study on the sensitivity of dogs to digitalis from hemodynamic aspects revealed the significant relationship between sensitivity to digitalis and hemodynamics. Furthermore, a close correlation was found between cardiac output and appearance time of dye dilution curve. Materials and Methods Healthy adult dogs were anesthetized by intraperitoneal administration of sodium pentobarbital (35-50 mg/kg). After intubation with endotracheal tube, room air mixed with 100 per cent oxygen was given by respirator. Dye dilution curve was recorded at time intervals after injection of indocyanine green (2-3 mg) into the vena cava near the right atrium and by sampling from the femoral artery. Aortic pressure was measured by the catheter placed in abdominal aorta. Electrocardiogram was monitored and recorded. (1) The determination of cardiac output by the triangle method. In order to determine the cardiac output, Cambridge dye dilution curve recorder was used. The author's modified triangle method was per-formed for the determination of the area of dye dilution curve by the following equation: fcdt = ΔXYZ + 1/10 ΔXYZ since Cambridge dye dilution curve recorder did not show lineality between dye concentration and absorbance in this experiment. (2) Hernodynamic studies on the sensitivity of dogs to digitalis. Nineteen healthy adult dogs weighing 8-16 kg were used. Before administration of strospeside, electrocardiogram, aortic pressure and dye dilution curve were recorded. Thirty minutes after intravenous administration of 0.3 mg/kg of strospeside, the dogs were divided into two groups electrocardiographically; The first group included dogs in which ventricular tachycardia continued more than thirty minutes or ventricular arrest occurred, the second group included dogs in which ventricular tachycardia did not occur or appeared transiently. Then the differences of hemodynamic and electrocardiographic findings before administration of strospeside between two groups were surveyed.
