The role of
digoxin in treatment of cats with
dilated cardiomyopathy and other forms of
myocardial failure is unclear. We evaluated the chronotropic and inotropic effects of
digoxin by comparing baseline, noninvasive indices of cardiac performance with those obtained after 9 +/- 1.3 (mean +/- SEM) days of
digoxin treatment in 6 cats with
heart failure attributable to
dilated cardiomyopathy. Two-dimensionally directed, M-mode echocardiography and electrocardiography were used to determine left ventricular shortening fraction, preejection period (PEP), ejection time (LVET), PEP to LVET ratio, velocity of circumferential fiber shortening, electromechanical systole, heart rate, and PR interval. Treatment consisted of administration of
furosemide (mean dosage, 2.4 mg/kg of
body weight/day),
digoxin in
tablet form (approximately 0.01 mg/kg, q 48 h),
aspirin (80 mg, q 48 h), and a commercial
low-salt diet. In addition, 2 cats were administered short-term, low-dose fluids IV, and 2 were given
taurine supplementation at rates of 500 and 1,000 mg/day. Other off-loading or inotropic agents were not administered. Therapeutic or toxic serum
digoxin concentration was achieved in all cats. Significant (P less than 0.05) improvement was detected in mean values for shortening fraction, PEP, PEP to LVET ratio, and velocity of circumferential fiber shortening. Mean electromechanical systole and LVET did not change significantly. Improvement, as assessed by indices of cardiac function, was documented in 4 of the 6 cats treated with
digoxin, including the 2 cats given
taurine supplementation. In the cats given
taurine, positive inotropic effect was observed prior to the time when
taurine-induced improvement in ventricular function is detectable.(ABSTRACT TRUNCATED AT 250 WORDS)