Atrial tachycardia facilitating initiation of ventricular tachycardia.

A 17-year-old male was studied because of clinically documented tachycardias showing narrow and wide QRS complexes. He was found to suffer from an atrial and a ventricular tachycardia. It was demonstrated that initiation of ventricular tachycardia occurred on reaching a critical ventricular rate during atrial tachycardia. Our study illustrates the value of electrophysiological studies in patients suspected of suffering from double or multiple tachycardias. It also shows that the occurrence of one type of tachycardia may be critically related to another type of tachycardia.