Hyperventilation facilitates induction of supraventricular tachycardia: A novel method and the possible mechanism

Hyperventilation and Supraventricular Tachycardia. Introduction: Hyperventi lation has been demonstrated to alter autonomic function. Sympathomimetic d rugs (isoproterenol) and parasympatholytic drugs (atropine) may be needed t o facilitate induction of supraventricular tachycardia (SVT). The aim of th is study was to test the clinical utility and mechanisms of hyperventilatio n to facilitate SVT initiation. Methods and Results: Fourteen patients with clinically documented SVT (9 AV nodal reentrant tachycardia and 5 AV reciprocating tachycardia) but nonind ucible during baseline electrophysiologic study were included. Immediately after hyperventilation test (at least 30 respirations/min) for 2 minutes, s ystolic blood pressure, sinus cycle length, anterograde and retrograde 1:1 conduction, and induced SVT were measured. Arterial blood gas, pH, and hear t rate variability before and after hyperventilation were measured. Seven o f nine patients with AV nodal reentrant tachycardia and 3 of 5 patients wit h AV reciprocating tachycardia, could be induced immediately after the hype rventilation test. After hyperventilation, anterograde AV and retrograde VA 1:1 conduction were improved, sinus cycle length was decreased, and heart rate variability were decreased in both groups. Conclusion: Hyperventilation can facilitate induction of SVT. Improvement o f conduction properties and changes of autonomic function are the possible mechanisms.