Deleterious Clinical and haemodynamic Effects of V-A Retroconduction in Symptomatic Sinus Bradyarrhythmias (S.S.B.) Treated with V. V. I. Pacing: their Regression with A. A. I. Pacing

Summary

Fifty-six pts. with “isolated” Symptomatic Sinus Brady-arrhythmias (S.S.B.) treated by V.V.I. p., showed 1:1 V-A retroconduction. They were followed for a mean period of 51 monts (12-122 m.). Twentynine pts. (52%) showed a progressive deterioration of cardiac function and c. heart failure. A high incidence of a. fibrillation (46%), thromboembolic complications (12.5%) and of syncopal episodes was also observed. Total survival was 80%, and 50% of deaths occurred within 2 years from PM implantation. Of the whole group 18 pts., who were not in A. F. were studied by L. and R. heart catheterization before and after 5 m’ of temporary A.A. I. pacing was instituted to a p. rate sufficient to inhibit the V. V.I. apparatus. Mean aortic pressure showed an increase(m.) of 20%, C. Index increased from a mean 2.6 (range 2.2-3.1) to 3.5 (3.2-4.0), mean P. wedge p. decreased from a mean of 17.8 mmHg (12-24) to 12 mmHg (9-14), R.A.P. from 13.7 (8-18) to 5.5 mmHg (3 - 7). These changes were all statistically significant. No statistically significant variations were seen for P.A.P., RVEDP and LVEDP. Permanent A.A.I. pacing was therefore instituted in all 18 pts.After a mean follow-up period of 2 yrs. survival is 100%, all pts. are still asymptomatic and no complications have occurred. The c1inical-haemodynamic deleterious effects due to V-A retroconduction (in pts. with S.S.B. and V.V.I. pms) are reversible using the A.A.I. mode of pacing which should be regarded as the treatment of choice for these conditions.