Precise determination of cardiac arrhythmias during open heart surgery monitoring of myocardial electrograms

Long-term observations of cardiac arrhythmias during and after cardiac surgery. I. Acquired heart disease

Twelve arrhythmias that occurred during and following surgery for acquired heart disease were studied in a group of 52 randomly selected patients. In cases of aortic and mitral valve replacement, Björk-Shiley prosthetic valves were used, and procain-magnesium-aspartate solution was applied for cardiac arrest. Registration and analysis of rhythm disturbances were carried out at 10 different time intervals, spaced narrowly in the intra-and early postoperative phases, then more widely up to the 96th hour of observation. Arrhythmic incidence and occurrence per case and phase are given, thereby allowing an account of transient arrhythmias as well. The peak occurrence of serious rhythm disturbance was found, intraoperatively, at about the time of aortic cross-clamping and release (ischaemic effect) with the exception of the mitral-commissurotomy group. The 1st-6th postbypass hours showed an arrhythmia trough, followed by a 2nd peak (9th-96th postoperative hour) made up of less serious arrhythmias (electrolyte- and acid-base disturbances; digitalis effects). All 12 arrhythmia types, as well as the five separately considered ventricular arrhythmias of the "first arrhythmia peak", did not reveal any significant relation to: patients' age, N.Y.H.A. criteria, pre-operative PAm or the duration of anaesthesia, surgery and bypass time.

Treatment of supraventricular tachycardias by rapid atrial stimulation

In 10 patients, 24 episodes of supraventricular tachycardia were treated by rapid electrical stimulation of the right atrium. One episode of sinus tachycardia, eight episodes of atrial tachycardia, two episodes of atrial flutter, and 13 episodes of A-V junctional tachycardia occurred. In each case the diagnosis of the arrhythmia was documented by obtaining unipolar and bipolar intra-atrial electrograms.

In three cases of supraventricular tachycardia the ventricular rate was slowed as a result of an increased atrial rate. The increased atrial rate caused an increase of the functional refractory period of the A-V junction, and thus, fewer atrial impulses were transmitted to the ventricles.

In seven cases, 21 episodes of supraventricular tachycardia were terminated by rapid atrial stimulation. In six of these cases the tachycardia was converted to normal sinus rhythm either during or shortly after atrial stimulation. In one case, 12 episodes of A-V junctional tachycardia were converted to rhythms varying between normal sinus rhythm and a slow A-V junctional rhythm. In this case, after termination of the last episode of A-V junctional tachycardia, the rhythm was stabilized by atrial pacing.