Prolonged asystole provoked by head-up tilt testing.

Area of Science:

• Cardiology
• Neurology
• Autonomic Nervous System

Background:

• Neurocardiogenic syncope (NCS) is a common cause of syncope.
• Diagnostic challenges exist, especially when initial tests are inconclusive.

Observation:

• A patient with a history of syncope presented with a positive head-up tilt test, inducing a 34-second asystole.
• Orthostatic symptoms were observed at a 75-degree tilt.
• High-frequency heart rate variability preceded asystole, suggesting vagal stimulation.

Findings:

• The head-up tilt test proved crucial for diagnosing NCS, revealing asystole despite a normal Schellong test.
• Heart rate variability analysis provided insights into the pathophysiology of NCS.

Implications:

• This case highlights the indispensable role of the head-up tilt test in diagnosing NCS, even with normal results from other tests like the Schellong test.
• Propranolol demonstrated efficacy in managing this patient's NCS.