H. Nordin et al., THE EFFECTS OF PROPRANOLOL AND VERAPAMIL ON HYPERTHYROID HEART SYMPTOMS AND FUNCTION, ASSESSED BY SYSTOLIC-TIME INTERVALS, Acta endocrinologica, 128(4), 1993, pp. 297-300
The effects of acute and chronic administration of propranolol and ver
apamil on heart rate and systolic time intervals were studied in 10 hy
perthyroid patients and 10 normal subjects, both groups without signs
of cardiovascular or pulmonary disease. In normal subjects iv proprano
lol reduced heart rate significantly, and both drugs increased the tot
al electromechanical systole significantly without difference between
the drugs. This effect was insignificant when the drugs were given ora
lly. In hyperthyroid patients both drugs reduced heart rate significan
tly in acute and chronic administration. and no difference between the
two drugs was found. Neither drug altered cardiac contractility as as
sessed by systolic time intervals. These results indicate that the met
abolic effects of thyroid hormone on contractility were unaltered and
unblocked by the drugs. None of the participants developed signs of he
art failure. Verapamil can thus be used as an alternative to propranol
ol in the treatment of tachycardia in hyperthyroidism.