ANALYSIS OF RANDOMNESS OF ATRIAL AND VENTRICULAR RHYTHM IN ATRIAL-FIBRILLATION

The aim of the present study was top examine the relationship between randomness of atrial and ventricular rhythm during atrial fibrillation . Atrial fibrillation was induced in 10 open-chest pigs by application of metacholine on the surface of the right atrium followed by increme ntal pacing. Local atrial rhythm (AA intervals) was recorded with a bi polar epicardial electrode, and episodes of atrial fibrillation corres ponding to 500 ventricular (RR) intervals were selected for analysis. Randomness of the distribution of AA and RR intervals was assessed by autocorrelation. Pearson's test was used for statistical analysis. Ran dom AA and RR interval distribution was observed in nine pigs (P great er than or equal to 0.05). In the remaining pig, atrial fibrillation h ad changed to atrial tachycardia. This was associated with immediate t ransition of a random to a non-random ventricular rhythm. These findin gs provide strong circumstantial evidence in support of the contention that randomness of ventricular rhythm during atrial fibrillation is d ue to randomness of atrial rhythm.