A 54-year-old male presents to the emergency department with complaints of episodic palpitations and lightheadedness. On examination, his heart rate is 150 bpm, consistent with narrow-complex tachycardia on ECG. Vagal maneuvers such as bearing down fail to terminate the rhythm. After ensuring no carotid bruits or contraindications such as recent stroke or carotid artery disease, a carotid sinus massage is performed on the right side while monitoring the ECG. Which of the following mechanisms underlie the effectiveness of carotid sinus massage?
