[Plasma electrolytes in patients with paroxysmal supraventricular arrhythmia]

In 50 patients treated for paroxysmal supraventricular tachycardia or paroxysmal atrial fibrillation, plasma concentrations of potassium, magnesium and calcium were determined during arrhythmia and after 20, 60, and 180 minutes from the return of sinus rhythm. For achieving normal rhythm digitalis, quinidine and isoptin were used or electrical cardioversion was performed. No patient received potassium of magnesium preparations during observation. It was found that: 1. In patients with paroxysmal supraventricular arrhythmia a significant increase of plasma potassium concentration was observed after regression of arrhythmia. The highest potassium concentration was found after 60 minutes from the return of sinus rhythm. 2. The increase of potassium concentration was higher in patients after episode of supraventricular tachycardia than atrial fibrillation. 3. In patients with short-lasting arrhythmia (up to 3 hours) the increase of potassium concentration after achieving normal rhythm was higher than in patients with longer-lasting arrhythmia. 4. In patients with supraventricular tachycardia and atrial fibrillation a significant decrease of plasma magnesium and calcium concentrations was found after restoration of sinus rhythm.