The role of pacing for the management of neurally mediated syncope: carotid sinus syndrome and vasovagal syncope.

The role of permanent cardiac pacing for the management of neurocardiogenic syncope is controversial; however, it does have a secondary role in appropriately selected individuals. Neurocardiogenic syncope includes vaso-vagal and enhanced antagonism of sympathetic-parasympathetic mechanisms. Differentiation of the so-called cardiac inhibitory, vasodepressor, and mixed forms of these disorders is frequently misleading when establishment of effective treatment strategies is attempted. Cardiac pacing can artificially restore near-normal heart rate and atrioventricular synchrony during a neurocardiogenic syncopal episode; however, cardiac pacing does not alter the peripheral vasodilatation, nor does it prevent the occurrence of the reflux response. Syncopal patients with carotid sinus hypersensitivity or vasovagal responses that include marked bradycardia and loss of atrioventricular synchrony can be supported by dual-chamber cardiac pacing in combination with other therapeutic interventions that diminish the severity of the reflex response. The conditions of patients with carotid sinus syndrome and carotid sinus hypersensitivity are frequently improved with cardiac pacing, and the conditions of elderly patients with vasovagal syncope are commonly improved with artificial pacing. The classic younger patient with malignant vasovagal syncope derives less benefit from artificial pacing; however, in carefully selected persons dual-chamber pacing combined with drug therapy and education decreases syncopal episodes and permits a return to normal activities.