This case illustrates differential vagal effects on dual AV nodal pathways, where left-sided vagal stimulation selectively impaired fast pathway conduction leading to hemodynamic compromise that was successfully treated with AV sequential pacing.
AV sequential pacing may alleviate symptoms from asymmetric vagal AV nodal effects; hypothesis-generating and should not yet change practice.
This 52-year-old male presented with syncope and demonstrated two distinct PR intervals on the electrocardiogram. Electrophysiologic studies showed dual AV nodal pathways. Right-sided carotid sinus massage induced prolonged periods of sinus arrest with no change in AH interval. Left-sided carotid sinus massage produced long AH intervals (slow pathway conduction) with some slowing of sinus rate. Whenever sinus rhythm with slow pathway conduction was observed (long AH) a 20-30 mmHg drop systolic pressure was seen. Following implantation of an AV sequential pacemaker, the patient has been asymptomatic.
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Ezri et al. (1983) studied this question.
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