CLINICAL ECG OBSERVATIONS ON INTRA-ATRIAL PACEMAKERS AND THEIR CONDUCTION

Four cases of multiple atrial parasystole with 2-3 atrial ecitopic pacemakers are presented with the ECGs. Three are ischemic heart disease with complete AV block, recognized as supranodal in nature according to James’ criteria. The remaining case is acute inferior wall myocardial infarction with paroxysmal auricular fibrillation. Careful observation of the ECGs show 3 varieties of A waves, A1 wave of right atrial type, A2 wave of left atrial type as well as retrograde A3 wave of coronary sinus type. Double parasystoles, atrial fusion beats and exit block are also shown. Detailed measurements show the rate of each ectopic pacemaker and mutual interference of the sinus pacemaker and ectoipic pacemaker forming reversed coupling. These findings further support James’ hypothesis on the intra-atrial conduction system.