—We appreciate the observations of Primavera and Del Sette about the possibility that the reported1 episodes of unresponsiveness were caused by diffuse brain ischemia secondary to cardiac dysrhythmias. While we considered this possibility, evidence to support it was lacking. During unresponsiveness, the patients' electrocardiograms revealed no dysrhythmias, and at no time during their hospitalizations were dysrhythmias observed (including time of the Holter monitoring in one patient). This does not totally exclude the possibility that each episode was triggered by a transient dysrhythmia that did not persist into the often quite prolonged periods of unresponsiveness. But we believe that these observations weigh strongly against that possibility. Moreover, despite long periods of unresponsiveness (up to 5 hours), none of the patients exhibited new neurologic findings on regaining responsiveness, as we would have expected had they sustained brain ischemia severe enough to cause unresponsivness of this duration.
Haimovic IC, Beresford R. Cardiovascular Investigation in Elderly Patients With Transient Unresponsiveness-Reply. Arch Neurol. 1992;49(11):1112. doi:10.1001/archneur.1992.00530350022013