Estudo do comportamento autonômico dos ritmos de escape no bloqueio atrioventricular congênito / Study of the Autonomic Behavior of the Escape Rhythms in Complete Congenital Heart Block

PURPOSE--To study the autonomic behavior of the escape rhythm in congenital complete heart block (CCHB), using heart rate variability (HRV). METHODS--A group of 10 asymptomatic patients with CCHB and narrow QRS was studied, 7 females; mean age = 14 +/- 9 years. The following time domain indexes were analyzed from a 24 hour Holter monitoring. The mean of all RR intervals (NN); the standard deviation of the mean (CLV5); the mean of all standard deviations (SDNN); the percent of successive differences longer than 50 ms (pNN50); the shortest cycle (CC) and the longest cycle (CL). The results were compared with a control group, using the Wilcox test for statistical analysis. RESULTS--The results were: NN = 1016 +/- 276 ms in CHB and 725 +/- 121 ms in control (p < 0.01); CLV5 = 184 +/- 97 ms in CHB and 125 +/- 38 ms in control (p = NS); SDNN = 102 +/- 32 ms in CHB and 88 +/- 29 ms in control (p = NS); rMSSD = 113 +/- 69 ms in CHB and 78 +/- 28 ms in control (p = NS); pNN50 = 43 +/- 26 per cent in CHB and 33 +/- 12 per cent in control (p = NS); CC = 582 +/- 129 ms in CHB and 333 +/- 49 ms in control (p = 0.05). CONCLUSION--No statistical difference was noted by comparing HRV indexes in CHB with control subjects, showing that the autonomic behavior of the escape rhythm in CCHB is similar to the sinus node in asymptomatic patients. The differences in NN, CC and CL are probably related to intrinsic properties of each command

Significado por intervalo PR prolongado em pacientes com bloqueio dos ramos do feixe de his do tipo bifascicular / Significance of prolonged PR interval in patients with bundle of his branch block type bifascicular

Purpose­Evaluation of the prolonged PR interval and its predictive value for trifascicular block in individuals with bifascicular His bundle branch block. Patients and Methods­55 patients, 36 male and 19 female aged 57 + 15,8 years with bifascicular bundle branch block type have been studied. 11 cases had complete left bundle branch block and 44 cases had complete right bundle branch block with left anterior ana superior division block. His bundle electrogram and atrial stimulation were performed in all patients. The atrial stimulation rate originating the Wenckebach phenomenon (SP) of the A-V conduction, and the A-H and H-V intervals were compared with the PR interval of the surface electrocardiogram. Patients were divided into three groups according to the PR interval: group 1, Pr < 200 ms, group II, PR between 190-280 ms and group III,PR 280 ms. Results­There was not linear correlation between the PR interval and WP in the three groups. There was a weak linear ascending correlation between the PR and A-H intervals in groups I and II (r + 0.59 and + + 0.43, respectively) and there was a descending correlation in the group III (r. - 0.64, P < 0.05). In relation to the H-V interval there was not linear correlation with the PR interval in groups I and II, but there was a good ascending linear correlation in the group III (r 0.84, P < 0.01). The incidence of prolonged A-H and H-V intervals increased as the PR interval was larger. Conclusion­ The prolonged PR interval with bifascicular bundle branch block means, in the majority of cases, diffuse damage of the conduction system envolving the A-V node and the infranodal region; starting from 280 ms, the delayed PR interval suggests envolvement predominantly below the A-V node: to a higher PR interval corresponds a higher H-V interval and also, to a relatively shortest A-H interval