Treatment of supraventricular tachyarrhythmias

MAST conversion of paroxysmal supraventricular tachycardia in Wolff-Parkinson-White syndrome

A 48-year-old man with Wolff-Parkinson-White syndrome presented with paroxysmal supraventricular tachycardia. Prior episodes had required inpatient drug therapy or cardioversion. Attempts at conversion to normal sinus rhythm with vagal maneuvers were unsuccessful. Inflation of military antishock trousers resulted in rapid termination of the arrhythmia and avoidance of hospitalization.

The effect of patient position and MAST inflation on carotid sinus diameter

A comparison of several maneuvers that are believed to increase vagal tone was made by measuring the carotid sinus with an ultrasound device. For 20 healthy volunteers the mean carotid sinus diameter was 5.7 mm supine, 6.1 mm in the Trendelenberg position, 6.5 mm after supine medical antishock trousers (MAST) inflation, 7.0 mm after MAST inflation in the Trendelenberg position, and 7.3 mm during a headstand. Each mean value was significantly different (P less than .01) from each of the others. These results have important implications for the treatment of dysrhythmias such as paroxysmal supraventricular tachycardia.

Procainamide infusion and acute atrial fibrillation

We report the use of intravenous procainamide infusion in the treatment of fifteen patients with acute atrial fibrillation. Procainamide was infused at 50 mg/min to a maximum of 20 mg/kg, with blood pressure and electrocardiographic monitoring. Ten patients responded, with a mean dose of 8.7 (standard deviation 4.3) mg/kg, four of these reverting to sinus rhythm after a low dose of less than 5.0 mg/kg. Hypotension was a common concomitant and was seen in four cases, but required termination of the infusion only in a patient with cardiomyopathy. An increase in ventricular rate or conversion to atrial flutter was not seen. Intravenous infusion of procainamide is a safe and moderately effective method of cardioversion in acute atrial fibrillation.