Exaggerated Valsalva maneuver may explain stretch syncope in an adolescent.

We describe cardiovascular responses during the Valsalva maneuver and syncope in the youngest reported patient with stretch syncope, which was induced by neck stretching and back hyperextension. The pattern of cardiovascular responses during stretch syncope was similar to that during a pathologic Valsalva maneuver, indicating adrenergic dysfunction in this patient. These findings indicate that the underlying mechanisms of these two processes are not fundamentally different, and that adrenergic dysfunction observed during the Valsalva maneuver may have resulted in stretch syncope in this patient. However, a simple Valsalva maneuver should not have sufficed to precipitate these episodes, because no syncope or significant hypotension occurred during the Valsalva maneuver. Thus, we suggest that additional factors, such as mechanical compression of vessels or physiologic responses to orthostasis, were aggravated during pathologic Valsalva maneuver responses, which were responsible for the stretch syncope observed.