Atrial Standstill Secondary to Atrial Inexcitability (Atrial Quiescence)

Atrial standstill secondary to atrial inexcitability or atrial quiescence was diagnosed in 11 patients and atrial standstill, in which atrial excitability was still present though depressed, was diagnosed in two patients during the immediate period following open-heart surgery. Atrial quiescence was successfully treated in six patients and atrial standstill with depressed excitability in both patients by the infusion of small doses of isoproterenol. Atrial quiescence was not treated in the other five patients and reverted spontaneously within 24 hours after surgery. It is suggested that atrial quiescence results from relative depolarization of the atrial membrane and that the success of therapy with isoproterenol results from hyperpolarization of the atrial membrane by this drug.