Cat naps

Sheldon Singh and associates1 conclude that their patient's symptoms of presyncope “may have been due to the weight of her cat on her right carotid sinus.” However, they report that multiple pauses of 3–4 seconds' duration, associated with vomiting and syncope, were observed while the patient was in the emergency department, without the cat.1

Hypersensitive carotid sinus syndrome (as diagnosed in this patient) and severe sick sinus syndrome commonly occur together. The superiority of dual-chamber, atrially based pacing of these patients has been demonstrated in VVI (ventricular demand pacing) to DDD (fully automatic pacing) crossover studies.2 In addition, the British Pacing and Electrophysiology Group has recommended selecting a pacing mode with as many features of normal sinus rhythm as possible,3 and Moller and colleagues4 demonstrated that prescribing relatively contraindicated3 products for older patients represented a false economy.

In the case reported by Singh and associates,1 a single-lead (ventricular) pacemaker was inserted. Thus, the patient would be wise to keep the cat off her neck in future because she has been given an inferior device, activation of which can sometimes be severely vasodepressive in patients with retrograde conduction. The statement by Singh and colleagues1 that “cardiac pacing is … not [helpful] for those [patients] with vasodepressor response” relates primarily to use of ventricular pacing; in contrast, many patients with severe hypotensive syndromes can be rendered more or less asymptomatic if they are given a device with high-rate, dual-chamber pacing response to the associated sudden drops in heart rate.5

G. Frank O. Tyers Department of Surgery University of British Columbia Vancouver, BC