Clinical and experimental observations in which bundle branch block patterns (BBBP) in ECG leads were normalized by distal His bundle (H) pacing are reported. The clinical material includes four patients with acute right BBBP secondary to anterior wall myocardial infarction and three patients with chronic left BBBP. Six of the seven patients had a prolonged H-V interval (60-85 msec) including three who showed evidence of an intra-H conduction delay (IHCD) with split H (H and H'). Distal H pacing from a right-sided electrode catheter normalized the BBBP with a stimulus-to-QRS (PI-V) interval 20-35 msec shorter than the H-V interval and almost identical to the H'-V interval in the three patients with documented IHCD. In 18 dogs ligation of the anterior septal artery resulted in IHCF with split H associated with right or left BBBP. Distal H pacing from catheter and/or plunge wire electrodes normalized the BBBP in 12 experiments (67%) with a PI-V interval identical to the H'-V interval. H pacing was selective and direct stimulation of myocardium was excluded by monitoring the high ventricular septal electrogram. The clinical and experimental observations are discussed as evidence that functional longitudinal dissociation is probably only operative in the pathologic H due to selectively greater depression of conduction in the transverse interconnections.
SUMMARY To describe the epicardial ventricular activation sequence in the intact human heart, we obtained epicardial maps from 11 patients with normal QRS undergoing open heart surgery. Epicardial breakthrough (EBT), defined as the emergence of a radially propagating epicardial wavefront, occurred in three to five sites in each patient, and was earliest in the anterior right ventricle, 7-25 msec (mean 17 msec) after the onset of the QRS in all patients. Subsequent EBT occurred in the inferior right ventricle (10 sites in 10 patients), in the anterolateral left ventricle (13 sites in 10 patients), and the inferior left ventricle (eight sites in seven patients). Latest epicardial activation (LEA), defined as the latest site of recordable epicardial activity, occurred in the basal segments in all patients, anteriorly in the right ventricle in five patients, and inferiorly in six patients, four on the right and two on the left. LEA occurred 63-96 msec (mean 77 msec) after the onset of the QRS, and was recorded within 20 msec of the end of the QRS in all patients. Sequence of epicardial activation reflected a fusion process among the wavefronts. This descriptive and quantitative data should provide a suitable basis for comparison of abnormal ventricular activation sequences in patients undergoing surgery for preexcitation or ventricular tachycardia.MOST DESCRIPTIONS of ventricular activation in the mammalian heart are derived from canine experimentation using epicardial and multiple intramyocardial electrodes.'" Sporadic observations have been made in the human heart under a variety of surgical conditions in the last 50 years, relating mostly to unipolar QRS morphology.8-13 In 1970, Durrer et al. described the epicardial and intramural activation sequence in seven extirpated, reperfused human hearts.'4 The activation of the human heart was found to be different in several ways from the dog heart.Extensive epicardial mapping of the intact human heart has become feasible, as a result of the experience gained with mapping of patients with cardiac arrhythmias. In this study, we systematically report observations of epicardial activation in the intact human heart, describing and quantitating the range of normality in epicardial activation sequence in 11 patients undergoing open heart surgery. Material and Methods Patient SelectionWe reviewed ECGs of patients scheduled for open heart surgery at
SUMMARY In January 1975, we reported results of a prospective follow-up study (mean 538 ± 42 days) of 119 patients with chronic bifascicular block (BFB), and concluded that BFB patients with normal and prolonged HV (NHV and PHV) had a similar incidence of atrioventricular (AV) block and mortality. In this report, we update these findings in 517 patients with a follow-up of 21 days to 9.8 years (mean 3.4 ± 0.2 years). Three hundred nineteen patients (61%) had NHV and 198 (39%) had PHV (> 55 msec). The NHV and PHV groups were similar in regard to age (NHV vs PHV, 61 ± 1 vs 62 i 1 years) and sex (80% male, 20% female vs 82% male and 18% female). The following were more common (p < 0.05) in patients with PHV (percent of patients with finding in NHV vs PHV groups): angina (18% vs 27%), congestive failure (27% vs 42%), cardiomegaly (48% vs 66%), New York Heart Association functional class II-IV (34% vs 56%), premature ventricular complexes (20% vs 29%), and organic heart disease (OHD) (75% vs 85%). Spontaneous trifascicular block (TFB) developed in two patients (0.6%) with NHV and nine patients (4.5%) with PHV (p < 0.05). Cumulative 7-year incidence of TFB was 3% with NHV and 12% with PHV (p < 0.01). Seven-year cumulative cardiovascular mortality was 32% in NHV patients and 57% in PHV patients (p < 0.005).In conclusion, PHV in patients with chronic BFB was associated with a greater incidence and severity of OHD, and higher total and sudden death mortalities. The risk of spontaneous TFB was small in patients with either NHV or PHV, although it was significantly higher in the latter.THE CLINICAL SIGNIFICANCE of a prolonged HV interval in patients with chronic bifascicular block has been controversial. Scheinman et al.1' 2 and Narula et al.3 reported a higher incidence of atrioventricular (AV) block and a higher mortality in patients with bifascicular block and prolonged HV interval than in those with a normal HV interval. On the other hand, in an early analysis of our data, we reported no significant differences in the short-term follow-up regarding risk of AV block and mortality in 119 patients with bifascicular block, comparing patients with normal and prolonged HV intervals.4 McAnulty and co-workers confirmed our findings.'To resolve this controversy, we analyzed our experience in our series of patients with chronic bifascicular block. In this study, we examine and compare clinical, electrocardiographic and electrophysiologic variables in bifascicular block patients with normal and prolonged HV intervals. We also report prospective observations concerning life history of these patients to determine the prognostic significance of the HV interval.Our Circulation 64, No. 6, 1981No. 6, . 1265 believe that our data can be reconciled with previous data concerning the significance of the HV interval in patients with chronic bifascicular block. Materials and MethodsDefinitions are based on the recommendations of the Criteria Committee of the New York Heart Association.6 The criteria for electrocardiographic diagnosis of r...
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