Multifocal ventricular parasystolic tachycardia.

Two cases of spontaneous multifocal ventricular parasystolic rhythm are described. One case showed double and the other fivefold parasystole. All seven foci had an enhanced rate of discharge, ranging from 57 to 102/min and at least three of them showed exit block. Though beats from three foci displayed very short coupling intervals, occasionally interrupting the terminal part of the preceding T wave, in none of the cases was repetitive firing or ventricular fibrillation seen. Both patients had organic heart disease and both are still alive six months after the arrhythmia was first recorded. Problems in the diagnosis of multiple parasystole and some mechanisms which may be responsible for irregular interectopic intervals are discussed. It is concluded that multiple parasystole is probably not a very rare arrhythmia if long strips of simultaneously recorded multiple leads are available.