Psychosomatic digitalis-toxic arrhythmias in guinea pigs

Adult male guinea pigs were subjected daily to six 1 min tone/light signals, each 5 min apart. For half of the animals, the signal was followed by rump shock 40% of the time (signal, shock group); for the remaining animals, shock was never delivered (signal, no-shock group). Animals in both groups were subjected to weekly injections of ouabain, a fast-acting digitalis glycoside. For the signal, shock group, significantly more potentially lethal arrhythmias began during the signal than the min preceding it. Also, a significantly higher percentage of arrhythmias began during the signal periods for the signal, shock group when compared to the signal, no-shock group. These findings indicate that psychogenic factors may contribute to the development of digitalis-toxic arrhythmias.