What is the primary action of vagal maneuvers in SVT management?

Vagal maneuvers primarily serve to stimulate the vagus nerve, which plays a crucial role in controlling heart rate through the parasympathetic nervous system. When these maneuvers are performed, they can increase parasympathetic tone and decrease the conduction velocity through the atrioventricular (AV) node, effectively interrupting the reentrant circuits that often cause supraventricular tachycardia (SVT).

This stimulation helps to slow down the heart rate by promoting a transient heart rate reduction, allowing the heart to revert to its normal rhythm. Such methods include activities that prompt a vagal response, such as the Valsalva maneuver or carotid sinus massage. The success of these maneuvers in managing SVT underscores the importance of the vagus nerve in cardiac function regulation, making this the correct choice for the primary action of vagal maneuvers in SVT management.