Effect of baroreflex stimulation using phenylephrine injection on ST segment elevation and ventricular arrhythmia-inducibility in Brugada syndrome patients

Patients affected by Brugada syndrome (BrS) are at risk of sudden cardiac death specifically at rest, when vagal tone is high. The aim of our study was to assess whether a phenylephrine injection, which provokes a baroreflex stimulation, could induce modification of the ST segment elevation and ventricular arrhythmias. Baroreflex test was performed with the administration of phenylephrine (2 mu g/kg) to four highly symptomatic patients in a setting fully equipped for cardiac resuscitation. Phenylephrine injection induced a deep vagal stimulation with a decrease in the mean heart rate from 75 +/- 7 to 50 +/- 8 bpm and an increase in the mean systolic blood pressure from 141 +/- 14 to 204 +/- 46 mmHg. ST segment elevation was not modified and no ventricular arrhythmias were induced during the test. Although phenylephrine injection induced a major alpha-adrenergic vasoconstriction followed by an arterial baroreflex, this test failed to provoke ventricular arrhythmias or modification of the ST segment elevation in BrS patients.