The role of mechanical-electrical interaction in ventricular arrhythmia: evidence from a novel animal model for repaired tetralogy of Fallot.
ABSTRACT Pulmonary regurgitation and prolonged QRS duration of right bundle branch (RBB) block are common in repaired tetralogy of Fallot (TOF) and increase the risk of sudden death. We sought to establish an animal model to reflect both abnormalities. Twenty-one canines: group I (n = 7) received a surgical right ventricular outflow tract (RVOT) transannular patch plus pulmonary valve destruction; group II (n = 5) received RBB ablation and sham operation; and group III (n = 9) received combined interventions. Serial electrophysiological data were obtained up to 1 y. Procedure mortality was 27.6%. At 1 y, although severe pulmonary regurgitation was documented in most dogs in groups I (71%) and III (100%), progressive RVOT dilatation was noted in group III. RBB block was present in all dogs in groups II and III. However, the increments of QRS duration, QTc, JTc, and QT dispersion progression between 1 mo and 1 y were all greatest in group III. Ventricular arrhythmia events were frequent in group III (median 3.3/mo) but uncommon in groups I and II (median 1/mo). We have created a novel animal model that adequately reflects both the hemodynamic and electrophysiological characteristics of repaired TOF patients and can be applied to examine the risk of ventricular arrhythmias.
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ABSTRACT: The electrocardiographic pattern of right bundle branch block (RBBB) is routinely observed after transatrial repair of tetralogy of Fallot even though no ventriculotomy has been performed. The mechanism of this conduction disturbance was studied in 16 patients with tetralogy of Fallot and one patient with infundibular pulmonic stenosis. Preoperative ECGs and vectorcardiograms showed right ventricular hypertrophy and no RBBB. Epicardial activation maps were obtained before and after total surgical repair in all patients and after infundibular resection but before closure of ventricular septal defect (VSD) in four of these patients. After infundibular resection, RBBB appeared and activation was markedly delayed (greater than 30 msec) over the pulmonary outflow tract, but was unchanged over the body of the right ventricle. No further changes in ventricular activation occurred after closure of the VSD. This study shows that RBBB after transatrial repair of tetralogy of Fallot is usually produced by infundibular resection, but not by VSD closure, and is associated with delayed activation of the pulmonary outflow tract and base of the right ventricle which results from damage to portions of the right ventricular conduction system.Circulation 07/1979; 59(6):1241-52. · 15.20 Impact Factor
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ABSTRACT: Right bundle branch block (RBBB) was produced in five dogs by incising the main right bundle branch. Body surface isopotential maps of each of these dogs were obtained from 85 thoracic electrocardiograms using a mini-computer technique. In addition, the epicardial activaton process was obtained from the same dog, and were correlated with the map pattern. Following the incision, the following characteristic changes in the map pattern occurred: The ventricular activation was prolonged in RBBB as compared with normal. During the early stage of ventricular excitation, the maximum was shifted leftward due to the activation wavefronts in the left ventricle in contrast to the double septal activation in the control. A localized lower potential area (a concavity) which appears in the middle stage of activation within the anterior positivity as an initial representation of breakthrough was also shifted left-and-downward and delayed in appearance. The sudden change in the potential distribution subsequently observed occurred quite differently. The terminal excitation was characterized by the maximum occurring over the right chest in RBBB in contrast to the left chest in control. These changes in the pattern of the potential distribution were compatible with the changes in the ventricular excitation process. This result may be applied to human RBBB map interpretation.Circulation 02/1977; 55(1):49-54. · 15.20 Impact Factor
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ABSTRACT: This study quantitates semilunar valve regurgitation by Doppler measurement of flows. The patients selected had single semilunar valve regurgitation; the other semilunar valve was normal. For the regurgitant valve, forward and reverse flows were measured in the great vessel distal to the abnormal valve, and reverse flow was subtracted from total forward flow to yield net flow. Net flow was compared with forward flow distal to the normal semilunar valve. If all values were computed accurately, net flow should equal forward flow distal to the normal semilunar valve. Twenty patients were studied and 18 had satisfactory recordings. Mean flow in the normal great vessel (3,511 ml/min) was not significantly different from mean net flow in the vessel with the abnormal valve (3,590 ml/min). The correlation coefficient for the paired flow measurements was +0.91 (685 ml [standard error of the estimate]). The slope of the relation was 0.88 and the intercept was 502 ml. Percent regurgitation varied from 29 to 73% and the percentage generally corresponded to clinical estimates. It is concluded that this method, which includes an internal control for each patient, is useful and reasonably accurate for clinical use in patients with pulmonary regurgitation, and appears clinically useful in some patients with aortic regurgitation.The American Journal of Cardiology 08/1985; 56(1):131-5. · 3.21 Impact Factor