Conduction disturbances after surgical correction of ventricular septal defect by the atrial approach.

Conduction disturbances have been documented after correction of ventricular septal defects by the ventricular route. Recently, repair of the ventricular septal defect has been through the right atrium to overcome damage to the conduction system and a right ventriculotomy. Thirty-nine children with ventricular septal defects under the age of 5 years were operated upon by the atrial route (group 1). The incidence of conduction disturbances in this group was compared with that occurring in 19 children of comparable age with a ventricular septal defect repaired via a right ventriculotomy (group 2). Complete right bundle-branch block developed in 13 of 39 children (33.3%) in group 1, compared with 15 of 19 children (78.9%) in group 2. This was a statistically significant reduction in complete right bundle-branch block in group 1. The incidence of left axis deviation occurring with complete right bundle-branch block was similarly statistically reduced. Transient complete heart block and arrhythmias were not statistically different in the two groups. The atrial approach to the repair of the ventricular septal defect significantly reduced the incidence of complete right bundle-branch block alone and occurring with left axis deviation.     

Right bundle-branch block and left axis deviation in acute myocardial infarction

Of 114 patients with acute myocardial infarction admitted consecutively to a coronary care unit, 10 had recent antero-septal myocardial infarction associated with right bundle-branch block and obvious left axis deviation, and I had recent antero-septal myocardial infarction with right bundle-branch block and right axis deviation. Attention is drawn to the high mortality (7 out of 11 patients), due mainly to cardiogenic shock. Frequent complications were sudden complete heart block (5 patients) and ventricular asystole (4 patients) without previous lengthening of the atrioventricular conduction time. An external on-demand pacemaker was inserted in 10 patients, and no patient died of complete heart block or ventricular asystole.     

Conduction disturbances after surgical correction of ventricular septal defect by the atrial approach.

Conduction disturbances have been documented after correction of ventricular septal defects by the ventricular route. Recently, repair of the ventricular septal defect has been through the right atrium to overcome damage to the conduction system and a right ventriculotomy. Thirty-nine children with ventricular septal defects under the age of 5 years were operated upon by the atrial route (group 1). The incidence of conduction disturbances in this group was compared with that occurring in 19 children of comparable age with a ventricular septal defect repaired via a right ventriculotomy (group 2). Complete right bundle-branch block developed in 13 of 39 children (33.3%) in group 1, compared with 15 of 19 children (78.9%) in group 2. This was a statistically significant reduction in complete right bundle-branch block in group 1. The incidence of left axis deviation occurring with complete right bundle-branch block was similarly statistically reduced. Transient complete heart block and arrhythmias were not statistically different in the two groups. The atrial approach to the repair of the ventricular septal defect significantly reduced the incidence of complete right bundle-branch block alone and occurring with left axis deviation.     

Right bundle-branch block and left axis deviation in acute myocardial infarction.

Of 114 patients with acute myocardial infarction admitted consecutively to a coronary care unit, 10 had recent antero-septal myocardial infarction associated with right bundle-branch block and obvious left axis deviation, and I had recent antero-septal myocardial infarction with right bundle-branch block and right axis deviation. Attention is drawn to the high mortality (7 out of 11 patients), due mainly to cardiogenic shock. Frequent complications were sudden complete heart block (5 patients) and ventricular asystole (4 patients) without previous lengthening of the atrioventricular conduction time. An external on-demand pacemaker was inserted in 10 patients, and no patient died of complete heart block or ventricular asystole.     

Natural history of left bundle-branch block.

The purpose of this study was to examine factors associated with the development of complete left bundle-branch block and the prognosis in a group of people not in hospital, who had no clinical evidence of ischaemic or valvular heart disease. Twenty-nine cases of left bundle-branch block without clinical evidence of ischaemic heart disease were noted in the Manitoba cohort of 3983 men under observation since 1948. The most frequent electrocardiographic finding before development of left bundle-branch block was a normal electrocardiogram; left ventricular hypertrophy though infrequent, was the only abnormality significantly more common than in the rest of the group. The development of left bundle-branch block was associated with distinct leftward shift of the frontal plane mean QRS axis. The most frequent clinical cardiovascular event observed after development of the block was sudden death without previous clinical evidence of ischaemic heart disease. The five-year incidence of sudden death as the first manifestation of heart disease was 10 times greater in men with left bundle-branch block than in those without it.     

The electrocardiogram in apparently healthy men and the risk of sudden death.

The purpose of this study was to determine whether electrocardiographic abnormalities detected on a routine examination in men without clinical evidence of heart disease predicted sudden death in the absence of pre-existing clinical manifestations of heart disease. The Manitoba study consists of a cohort of 3983 men with a mean age at entry of 30.8 years who have been followed with regular examinations including electrocardiograms since 1948. During the 30 year observation period, 70 cases of sudden death have occurred in men without previous clinical manifestations of heart disease. The prevalence of electrocardiographic abnormalities before sudden death was 71.4% (50/70). The frequency of abnormalities was 31.4% (22) major ST segment and T wave abnormalities, 15.7/ (11) ventricular extrasystoles, 12.9% (nine) left ventricular hypertrophy (voltage criteria), 7.1% (five) complete left bundle-branch block, and 5.7% (four) pronounced left axis deviation. When these electrocardiographic findings in men without clinical manifestations of heart disease were related prospectively to incidence of sudden death each one except pronounced left axis deviation was a significant predictor of sudden death. Two of the variables were examined in more detail. Increased severity of primary T wave abnormalities and the association of ST segment and T wave abnormalities with increased QRS voltage further increased sudden death risk. The combination of ventricular extrasystoles with either ST-T abnormalities or left ventricular hypertrophy much increased the risk of sudden death. Thus these data indicate that electrocardiographic abnormalities detected on routine examination in men without clinical evidence of heart disease are significantly related to the occurrence of sudden death.     

Ventricular tachycardia due to sustained bundle branch reentry: Diagnostic and therapeutic considerations

We have identified bundle-branch reentry (BBR) as the mechanism of ventricular tachycardia (VT) during electrophysiologic studies in 48 patients at our institution. All but three patients had significant structural heart disease, that is, dilated ischemic or idiopathic cardiomyopathy, the most common of anatomic substrates. Syncope and sudden death were the modes of presentation in up to 70% of these patients. The critical prerequisite for the development of this arrhythmia is conduction delay in the His-Purkinje system, which was present in all patients and manifests as a nonspecific conduction delay or a left bundle-branch block (LBBB) in the surface electrocardiogram (ECG) and a prolonged HV interval in the intracardiac recordings. VT with an LBBB morphology is the most common form of BBR, present in 98% of patients. Transcatheter ablation of the right bundle branch (RBB) with the use of radiofrequency current is the treatment of choice, as it effectively eliminates BBR. During long-term follow-up, recurrent tachycardia due to BBR was not documented in any patient; however, congestive heart failure was a common cause of death in this population.     

心脏再同步化治疗心力衰竭伴传导阻滞患者的近期随访

目的 观察心脏再同步化治疗（CRT）心力衰竭伴传导阻滞患者心功能改善情况.方法 连续入选在我科住院的终末期心力衰竭患者45例,按照QRS时限、形态分为完全性左束支传导阻滞组、完全性右束支传导阻滞组和非特异性室内传导阻滞组,分别评估、测量三组患者术前及术后6个月的NYHA分级、左室舒张末内径（LVED）、左室射血分数（LVEF）及血浆B型利钠肽（BNP）浓度.结果 完全性左束支传导阻滞组和非特异性室内传导阻滞组患者术后NYHA分级改善[（2.8±0.3）级比（3.6±0.2）级,（2.9±0.3）级比（3.5±0.4）级,P＜0.05],LVED缩小[（67.2±7.5）mm比（74.2±6.5）mm,（66.4±9.9）mm比（75.8±9.1）mm,P＜0.05],LVEF增大[（33.6±7.7）％比（26.6±7.2）％,（44.4±5.1）％比（28.6±5.7）％,P＜0.05],血浆BNP浓度下降[（3988.4±628.3）pg/ml比（8542.6±1384.9）pg/ml,（3573.2±749.5）pg/ml比（6666.2±1110.5）pg/ml,P＜0.05];完全性右束支传导阻滞组NYHA分级没有改善[（3.3±0.2）级比（3.4±0.3）级,P＞0.05],LVED无变化[（61.2±5.0）mm比（62.4±4.3）mm,P＞0.05],LVEF没有增大[（35.2±12.3）％比（33.4±11.8）％,P＞0.05],血浆BNP浓度无明显变化[（6844.7±774.8）pg/ml比（7558.6±1327.4）pg/ml,P＞0.05].结论 心脏再同步化治疗能够改善完全性左束支传导阻滞及非特异性室内传导阻滞患者的心脏功能,不能改善完全性右束支传导阻滞患者的心脏功能.     

Conduction defects, ventricular arrhythmias, and late death after surgical closure of ventricular septal defect.

One hundred and eighty-seven patients who had surgical closure of a ventricular septal defect between 1958 and 1975 were followed for up to 21 years. there were 17 late sudden deaths of which eight occurred in completely fit patients while nine were already under medical care. In an attempt to elucidate possible risk factors and reoperative and serial postoperative electrocardiograms of all patients were studied. Fifty-one unselected healthy follow-up patients agreed to 24 hour ambulatory monitoring. Progressive exercise testing (Bruce protocol) was carried out on 31 of them and an additional seven patients. There was a significant correlation between recorded ventricular arrhythmias and conduction defects, particularly progressive conduction defects. Transient complete heart block carried a bad prognosis and grade 3-4b ventricular arrhythmias were a major risk factor and recorded in 10 of the 17 patients who died. Long-term postoperative electrocardiographic follow-up is recommended and 24 hour ambulatory monitoring and exercise testing complement the findings of the resting electrocardiogram. The long-term treatment of survivors found to have ventricular arrhythmias must be considered.     

Two cases of bi-ventricular dysplasia associated with ventricular tachycardia and familial occurrence of sudden death.

Two strikingly similar patients with arrhythmogenic right ventricular dysplasia which severely impaired not only the right ventricle but also the left ventricle are described in association with familial occurrence of sudden death. A 49-year-old man experienced syncope which was due to ventricular tachycardia. Electrocardiography revealed a first degree atrioventricular block, incomplete right bundle-branch block, T wave inversions in leads II, III, a VF and V1 to V5, and multiformal ventricular extrasystoles. Echocardiography and ventricular cineangiography showed not only the right ventricular dilatation with an aneurysm in the right ventricular apex, inflow and outflow tracts, but also mild dilatation of the left ventricle with left ventricular apical and posterior aneurysms. Radionuclide angiography also disclosed dysfunction of both ventricles, especially during exercise. His family history revealed that 3 members of his family died of sudden deaths. A 56-year-old woman experienced syncope secondary to ventricular tachycardia, with left bundle-branch block. Electrocardiography showed complete right bundle-branch block, left axis deviation, and T wave inversions in leads V1 to V4. Echocardiography and ventricular cineangiography revealed not only marked right ventricular dilatation with the "triangle of dysplasia", but also a left ventricular aneurysm in the apex and posterior portion. Her elder brother died of a sudden death, and electrocardiograms of 2 members of her family showed ventricular extrasystoles and T wave inversions. These 2 cases may well be termed "familial bi-ventricular dysplasia".     

Prognostic significance of arrhythmia in tetralogy of fallot after intracardiac repair

The significance of arrhythmia and conduction defects was studied in 395 patients who underwent intracardiac repair of tetralogy of Fallot between 1958 and 1976. In 91 of these patients (group I), the median date of repair was 1964 and all underwent stress testing. In 107 patients (group II), the median date of repair was significantly later (1971), but all subjects were too young for stress testing. The remaining 197 patients (group III, median date of repair 1963) included all those who did not participate in stress testing or who had died; 42 of these patients were later excluded from analysis because of insufficient electrocardiographic records. The overall incidence of any form of arrhythmia (19 percent) was the same for each group. However, in group II (patients who underwent intracardiac repair more recently), no tachyarrhythmia was observed and there were fewer patients with 1° atrioventricular (A-V) block (p <0.001) and more patients with complete right bundle branch block (p <0.001) than in groups I and III. In two patients (both in group I), unexpected, late sudden death unrelated to strenuous physical activity occurred. Arrhythmia was least common in patients with primary intracardiac repair and more common in those with either palliation before intracardiac repair or multiple intracardiac repairs. In group I, 41 of 91 patients with arrhythmia of even minor degree at rest (n = 13) or exercise (n = 28) had a significantly larger heart, greater right ventricular pressure and lesser exercise performance than did those without arrhythmia, thus suggesting the presence of residual abnormality or dysfunction. No tachyarrhythmia was induced by exercise in this study. Patients with either arrhythmia or bifascicular block have generally had a benign course without strong evidence of progression of arrhythmia.     

Histological substrate of ventricular tachycardias of the right bundle-branch block type (sensitive to verapamil)

In order to clarify the anatomic substrate of idiopathic ventricular tachycardia of right bundle-branch block morphology, responsive to verapamil, two patients with this type of arrhythmia were evaluated using hemodynamic studies, right ventricular endomyocardial biopsy as well as electrophysiological and pharmacological studies. Pressures, right and left ventriculography and coronary angiography were normal in both patients. Case 1 showed a prolonged sinus node recovery time and a histological pattern which was compatible with healed myocarditis. Case 2 presented a complete right bundle-branch block, intra-His conduction defects and histological features of aspecific cardiomyopathy. Our results underline the presence of diffuse ventricular histologic changes in patients with idiopathic ventricular tachycardia of right bundle-branch block morphology. These histologic changes seem unable to interfere with cardiac pump function but are sufficient to create significant abnormalities of impulse formation and conduction.     

The electrocardiogram in coronary disease

From an analysis of the electrocardiographic findings in sixty cases of coronary selerosis, T-wave inversion was found to be the most common abnormality, occurring in 88 per cent of the cases. Widened notched QRS was present in 13.3 per cent.Attention is called to certain less definite changes such as minor notching of the QRS without widening and also low voltage. An attempt is made to evaluate the significance of these changes.Increase in auriculoventricular conduction time was comparatively rare and found only associated with curves of bundle-branch block.The most frequent arrhythmia was the extrasystolic type, which was present in 18 per cent. Auricular fibrillation was present in only 6.6 per cent and only in those cases showing evidence of congestive heart failure.Preponderance curves of left ventricular type of definite or slight degree were noted in 60 per cent and slight right preponderance in only 3.3 per cent.The presence or absence of cardiac enlargement or congestive heart failure seems to have little effect on the type of electrocardiogram.A conception as to the practical application of electrocardiography in the diagnosis of coronary disease is suggested.     

Electrophysiological factors of left bundle-branch block.

Left bundle-branch block is rarely an isolated disorder of conduction, additional disorders being found in 29 of 30 patients studied by intracardiac stimulation techniques. These included disorders of sinus node function (prolonged maximum sinus node recovery time (corrected) in 23%, prolonged sinuatrial conduction time in three of eight patients), atrioventricular node function (prolonged AH interval in 33%, prolonged effective and functional refractory periods in 37% and 74%, respectively), "His bundle to right bundle branch" conduction (prolonged HV interval in 53%), and ventriculoatrial conduction (absent in 62%). It is postulated that at least half of the cases of left bundle-branch block were incomplete, even though the duration of the QRS complex exceeded 120 ms, because of (further) leftward deviation of the mean frontal QRS axis with sufficiently premature atrial extrastimuli. Block may be complete or incomplete in left bundle-branch block with left axis deviation of -30 degrees or more on the standard electrocardiogram.     

Prognosis of right bundle branch block and left anterior hemiblock after intracardiac repair of tetralogy of Fallot.

One hundred and forty-one survivors of intracardiac repair of tetralogy of Fallot (TOF), operated on between 1958 and 1972, were studied in order to document the incidence of right bundle branch block and left anterior hemiblock (RBBB and LAH) and to definite the late prognosis. RBBB and LAH occurred in 31 patients (22 per cent), all of whom have had complete follow-up. Transient complete heart block (CHB) occurred postoperatively in 2 patients; there were no other significant arrhythmias. Two late deaths have occurred, neither from arrhythmia (one from progressive congestive heart failure, and the other from attempted reclosure of a ventricular septal defect). The remainder of the patients are well an average of 76 months postoperatively (range, 144 to 12 months). The absence of late-onset CHB or sudden death in this series contrasts with the relatively high incidence of these events in some studies of RBBB and LAH after intracardiac repair of TOF. However, in those reports a history of transient postoperative CHB (indicative of trifascicular disease in this setting) can be found in 75 per cent of those who developed late-onset CHB or died suddenly. We conclude that the occurrence of RBBB and LAH after intracardiac repair of TOF does not of itself carry a bad late prognosis. The critical factor in a bad late prognosis in patients with ECG evidence of RBBB and LAH may be with ECG evidence of RBBB and LAH may be the history of transient postoperative CHB.     

Unexpected cardiac arrest in patients after surgical correction of tetralogy of Fallot.

Four of 220 patients without bifasicular block (complete right bundle branch block and left anterior hemiblock) or transient complete heart block immediately after surgery had an unexpected cardiac arrest one to 15 years after satisfactory surgical repair of tetralogy of Fallot. The postoperative electrocardiograms (ECG) revealed complete right bundle branch block in two patients and no intraventricle conduction abnormality in two patients. Each of the four patients had premature ventricular contractions on previous postoperative ECG. The cardiac arrest occurred during normal activity in three patients and mild exercise in one. Following the cardiac arrest, three patients died and one patient survived. Eighteen months before the cardiac arrest, the survivor had a stress test which revealed multifocal premature ventricular contractions with short bursts of ventricular tachycardia after exercise. This ventricular arrhythmia was suppressed with quinidine therapy. Although complete heart block cannot be excluded in these four patients, we reasoned that the cardiac arrests were probably preceded by ventricular tachyarrhythmia. Because of this experience, we believe that any patient who has had intraventricular surgery should be evaluated for ventricular arrhythmia. If frequent premature ventricular contractions or serious ventricular arrhythmias are documented, we seriously consider antiarrhythmic therapy in an attempt to prevent ventricular tachyarrhythmias and sudden death.     

Conduction defects in aortic valve disease

Serial electrocardiograms of 426 patients undergoing homograft replacement of the aortic valve were analyzed with respect to the presence or absence of conduction defects (CD) in an attempt to define more precisely their etiology and relationship to prognosis. The dominant lesion was aortic stenosis in 249 patients and aortic regurgitation in 177 patients. Preoperative CD were present in 69 patients (28 per cent) with aortic stenosis and in 43 patients (24 per cent) with aortic regurgitation. In those with aortic stenosis, calcification in the ventricular septum or impaired left ventricular function were common and could have been important etiological factors. In those with aortic regurgitation, impaired left ventricular function was the dominant feature. Coronary artery disease was present in a minority of patients in both groups. In patients with aortic stenosis, there were three early deaths (4.4 per cent) and 11 late deaths (15.9 per cent). In those with aortic regurgitation, there were four early deaths (9.3 per cent) and four late deaths (9.3 per cent). Of 275 patients with normal conduction throughout the pre- and postoperative period, there were 15 early deaths (5.4 per cent) and 13 late deaths (4.7 per cent). (Follow-up 3 to 84 months. Mean, 36 months). Reversal of CD following operation occurred in more than half of those patients with first-degree A.V. block regardless of the initial hemodynamic lesion and was associated with improvement in left ventricular function. Reversal of left anterior hemiblock (LAH) occurred in approximately 30 per cent of cases. Progression of LAH and the combination of left axis deviation with left bundle block (LBBB) were associated with a poor prognosis. Fresh CD following operation occurred in 19 patients within 1 month of surgery and in 20 patients beyond this period of time. In this group there were two early deaths (5.1 per cent) and four late deaths (10.3 per cent). Of 20 patients developing late conduction defects, six were associated with valve failure and the development of poor left ventricular function. In the remainder no apparent cause could be determined and this group may represent fibrosis occurring in the region of the conducting pathways.     

Severe postoperative heart blocks appearing late. 16 cases

Sixteen patients, aged 4 to 42 years, operated for congenital heart disease, presented, months or years after surgery, complete atrioventricular (11 cases) or sinoatrial block (5 cases). Six patients had transient complete atrioventricular block in the immediate postoperative period, the maximum duration of which was less than 30 days. The late postoperative period was defined as at least 6 months after surgery. The period between surgery and the implantation of a pacemaker varied from 9 months to 19 years, average 6,3 years. Analysis of long term electrocardiographic studies distinguished three types of progression: --group I: alternation of sinus rhythm and conduction defect until definitive block, sometimes presenting with syncope; --group II: sudden, severe conduction defect after a long period of sinus rhythm; --group III: progressive lengthening of the PR interval. Seven patients developed syncope; 4 had dizziness, 2 were short of breath; only 3 were asymptomatic. All underwent permanent pacing. The incidence of late conduction defects appears to be 1 to 2% of operated patients. The causes include progressive fibrosis, slow sclerosis extending over conduction pathways which are congenitally fragile. Most late blocks are of an advanced degree. Some may be responsible for unexplained sudden death. It is therefore desirable to avoid this complication by the judicious and considered implantation of a cardiac pacemaker. Some authors mention the following factors in deciding on the indications for pacing: --complete, transient atrioventricular block during the operation or the immediate postoperative period; --ECG appearances of right bundle branch block and left anterior hemiblock, or trifascicular block; --His bundle studies.(ABSTRACT TRUNCATED AT 250 WORDS)     

Familial cardiomyopathy underlies syndrome of right bundle branch block,ST segment elevation and sudden death

Objectives. We sought to assess whether structural heart disease underlies the syndrome of right bundle branch block, persistent ST segment elevation and sudden death.Background. Ventricular fibrillation and sudden death may occur in patients with a distinctive electrocardiographic (ECG) pattern of right bundle branch block and persistent ST segment elevation in the right precordial leads.Methods. Sixteen members of a family affected by this syndrome underwent noninvasive cardiac evaluation, including electrocardiography, Holter ambulatory ECG monitoring, stress testing, echocardiography and signal-averaged electrocardiography; two patients had electrophysiologic and angiographic study. Endomyocardial biopsy was performed in one living patient, and postmortem examination, including study of the specialized conduction system, was performed in one victim of sudden death.Results. Five years before a fatal cardiac arrest, the proband had been resuscitated from sudden cardiac arrest due to recorded ventricular fibrillation. Serial ECGs showed a prolonged PR interval, right bundle branch block, left-axis deviation and persistent ST segment elevation in the right precordial leads, in the absence of clinical heart disease. Postmortem investigation disclosed right ventricular dilation and myocardial atrophy with adipose replacement of the right ventricular free wall as well as sclerotic interruption of the right bundle branch. A variable degree of right bundle branch block and upsloping right precordial ST segment was observed in seven family members; four of the seven had structural right ventricular abnormalities on echocardiography and late potentials on signal-averaged electrocardiography. A sib of the proband also had a prolonged HV interval, inducible ventricular tachycardia and fibrofatty replacement on endomyocardial biopsy.Conclusions. An autosomal dominant familial cardiomyopathy, mainly involving the right ventricle and the conduction system, accounted for the ECG changes and the electrical instability of the syndrome.     

Conduction disturbances after correction of tetralogy of Fallot: are electrophysiologic studies of prognostic value?

Late complete heart block may occur after correction of tetralogy of Fallot. Whether postoperative electrophysiologic studies can identify patients at risk of developing this conduction disturbance is unknown. In this study, 57 children who underwent electrophysiologic investigation after correction of tetralogy of Fallot were followed up for 1 to 13 (mean 6.5) years after the investigation. One late death and two cases of late complete heart block occurred. The late death was due to ventricular arrhythmia and not to a conduction disturbance. The cases of late heart block occurred 2 and 5 years, respectively, after electrophysiologic study, and in both cases the patient had a prolonged HV interval; in one patient progressive lengthening of the HV interval could be demonstrated at two subsequent studies 1 year apart. Another five patients with a prolonged HV interval had normally conducted sinus rhythm up to 11 years after study. Atrial pacing at increasing rates (up to the occurrence of second degree atrioventricular block) during electrophysiologic study was the best means of predicting late heart block: of three patients with block below the bundle of His occurring at pacing rates less than 180/min, two developed late complete heart block. Thus, electrophysiologic testing of the conduction system after correction of tetralogy of Fallot is useful in predicting late complete heart block and should be performed in patients with a history of transient heart block after surgery and in those with a prolonged PR interval.