Ventricular Parasystolic Tachycardia.

Atrial parasystole and tachycardia. Modulation and automodulation of a parasystolic focus.

This report deals with a patient reflecting atrial parasystole and episodes of atrial tachycardia. The P' waves during tachycardia were identical to the parasystolic P' waves. Atrial parasystole was at times regular, as revealed by a precise mathematical relationship between the interectopic intervals, and on other occasions irregular. Irregularity was due to modulation, namely electrotonic inf...

Parasystolic ventricular tachycardia. Observations on differential stimulus threshold as possible mechanism for exit block.

Ventricular ectopic rhythms due to rapid runaway pacemaker.

A patient initially had syncope due to a runaway pacemaker firing at an unusually rapid rate (30 impulses per second). The ventricular arrhythmia was characterized by numerous ectopic beats, with coupling intervals related to the length of the preceding cycle and runs of ventricular tachycardia with slight variations in the intervals between beats. This case demonstrates the clinical characteri...

Multiform Ventricular Ectopic Rhythm

Six patients whose standard electrocardiograms showed multiform ventricular ectopic rhythm were studied. All patients had advanced organic heart disease and a significant intraventricular conduction defect (left bundle branch block in five and right bundle branch block plus left anterior hemiblock in one). The ventricular arrhythmia was generally resistant to antiarrhythmic therapy. Five of the...

Parasystole, reentry, and tachycardia: a canine preparation of cardiac arrhythmias occurring across inexcitable segments of tissue.

A protected ectopic focus created in tissue excised from one heart was allowed to interact with the activity of the intact heart of another animal. The protected focus consisted of a Purkinje fiber in which a narrow central zone was rendered inexcitable. The model permitted us to study parasystole, modulated parasystole, reentry, and tachycardia in the same preparation. At moderate levels of el...