Variants of development of complete atrioventricular block. Prognosis in disorders of intraventricular conduction

In a group of patients with complete atrioventricular block admitted for implantation of a cardiac stimulant, 15 out of 74 patients (20.3%) had normal intraventricular conduction before the block, while 59 (79.7%) had disorders of intraventricular conduction. A combination of right bundle-branch block with block of the anterior limb of the left branch was the most frequent occurrence (37.8%). Comparison of the QRS complexes in maintained atrioventricular conduction with those in complete antrioventricular block showed that among patients with disorders of intraventricular conduction complete atrioventricular block was of a proximal character in 45.5% and of a distal character in 54.5% of cases. There was a high risk of development of complete atrioventricular block in patients with right bundle-branch block combined with block of the anterior limb of the left branch; it was found to be 41.2% at an average follow-up period of 23 months.     

Restoration of sinus rhythm during two consecutive pregnancies in a woman with congenital complete heart block

In a woman with congenital complete heart block atrioventricular conduction was normal during two successive pregnancies. Pregnancy, labour, and delivery were uncomplicated on both occasions and complete heart block returned post partum.     

Restoration of sinus rhythm during two consecutive pregnancies in a woman with congenital complete heart block.

In a woman with congenital complete heart block atrioventricular conduction was normal during two successive pregnancies. Pregnancy, labour, and delivery were uncomplicated on both occasions and complete heart block returned post partum.     

Ventricular function and long-term pacing in children with congenital complete atrioventricular block

Objective: To determine the sequela of right ventricular pacing in children with congenital complete atrioventricular block.
Background: Pacing is a well-accepted therapy for patients with congenital complete atrioventricular block. The long-term sequela of right ventricular pacing in this population has not been well described.
Methods: We performed a cohort study on all patients with congenital complete atrioventricular block who underwent pacemaker implantation at our institution from 1972 to 2004. Patients with associated congenital heart disease or ventricular dysfunction prior to pacemaker implantation were excluded.
Results: A total of 63 patients were included in the study. The median age at pacemaker implantation was 6.5 years, with an average follow-up of 9.9 years. The cumulative dysfunction free survival at 20 years was 92%. In total, four patients (6%) were noted to develop LV dysfunction an average of 15.1 years after pacemaker implantation. Of 30 patients who were paced for >10 years, only three (10%) developed echocardiographic evidence of LV dysfunction. Right ventricular apex pacing and prolonged QRS duration were found to be predictive of decreased long-term LV systolic function (P < 0.05).
Conclusions: Left ventricular dysfunction in patients with congenital complete atrioventricular block is a rare finding, even in those who have been paced for more than 10 years. Right ventricular apex pacing and prolonged QRS duration may be associated with decreased ventricular function over time. At this time, with such a low incidence of cardiac dysfunction, right ventricular pacing should be considered an acceptable first-line therapy in this population.     

Cardiac pacemakers in children. 15 years' experience

Between 1971 and 1986, 85 pacemakers were implanted at the St Justine Hospital, Montreal, in 57 young patients (25 girls, 32 boys) then aged from one day to 23 years (mean 10.3 years). The patients were followed up for periods ranging from 15 days to 13.5 years (mean 4.5 years); 119 epicardial electrodes were positioned by thoracotomy in 52 patients and by sternotomy in 5 patients; the 85 pacemaker cases were placed in the left retroperitoneal cavity. The pacemakers were programmed in modes VVI (28), AAI (1) and DDD (28). The indications for pacemaker implantation were: complete atrioventricular block in 39 cases (postoperative 16, congenital 22, acquired 1), sinus node disease in 17 cases (postoperative 13, cardiomyopathy 3, normal heart 1) and Romano-Ward syndrome in 1 case. Operated heart diseases which required pacemaker implantation were: D-transposition of the great arteries in 17 cases (complete atrioventricular block 7, sinus node disease 10), tricuspid valve atresia in 3 cases (sinus node disease 3) and tetralogy of Fallot in 3 cases (complete atrioventricular block 3). Twenty-four patients underwent a total of 33 reoperations: 21 changes of battery, 12 changes of electrodes (6 for fibrosis, 6 for breakage). Only one patient developed infection of the pacemaker case. Altogether, the incidence of complications (infection and/or breakage) was low in this series, regardless of the pacing mode. Pacing in children is now an acceptable treatment with low risk provided the indications are well selected.     

Relationship between heart rate and rhythm, and cardiac performance assessed in the human fetus in utero

To evaluate the relationship between heart rate and rhythm, and cardiac performance, in the human fetus in utero, observed over a long-term period in gestation, we made a total of 138 studies in 114 fetuses from 18 to 41 weeks of gestation; 104 having heart rate changes without rhythm disturbances ("control group"), 6 with complete atrioventricular block and 4 with supraventricular tachycardia. Using M-mode echocardiogram, we measured end-diastolic dimension and fractional shortening in the right and left ventricles. The corresponding heart rate for each cardiac cycle was measured using the interval between two consecutive end-systolic points. In fetuses in the group of controls, the values for fractional shortening in both ventricles were almost constant with advancing gestational age, unrelated to an increase in end-diastolic dimensions of either ventricle. There was no correlation between changes in heart rate and changes in the value of ventricular fractional shortening at any period of gestation studied. In the fetuses with atrioventricular block, dimensions and fractional shortenings in both ventricles were significantly larger than those in the group of control fetuses at the same stage of gestation. This indicates that the fetal heart is capable of acclimatizing itself, beginning as early as 18-25 weeks of gestation, to long-lasting bradycardia in which an increased stroke volume would be required. In fetuses with supraventricular tachycardia, end-diastolic dimensions were larger and fractional shortening was significantly smaller in both ventricles than in fetuses from the control group from 26-30 weeks of gestation onwards. This suggests tachycardia-induced cardiomyopathy occurring during intrauterine life.     

Congenital Complete Atrioventricular Block and Preexcitation Syndrome: A Well-Matched Partner

A patient who had been previously diagnosed with congenital complete atrioventricular block (CCAVB) twenty years ago developed atrioventricular (AV) conduction through an accessory pathway (AP). With enhanced sympathetic tone (exercise, isoproterenol), 1:1 conduction down the AP occurred. An electrophysiologic study confirmed a suprahissian AV block and the presence of an AP. The AP was located on the left side and posterior. The absence of retrograde conduction through the AP and also a long conduction time were demonstrated.     

1:1 atrioventricular conduction in congenital complete heart block

A female neonate with congenital complete heart block developed atrioventricular conduction through an accessory pathway. Despite sinus rhythm and an adequate heart rate she developed severe dilated cardiomyopathy and died at age 14 months. This case illustrates that underlying heart block can be present in individuals with asymptomatic Wolff-Parkinson-White syndrome and that the dilated cardiomyopathy that occasionally accompanies autoimmune congenital heart block is not primarily caused by bradycardia.

Keywords: congenital heart disease; complete heart block; atrioventricular conduction; Wolff-Parkinson-White syndrome     

Permanent pacemaker implantation in infants, children, and adolescents. Long-term follow-up.

Twenty-four patients in the pediatric age range who underwent implantation of a cardiac pacemaker for treatment of complete atrioventricular (A-V) block were followed for an average of five years (range 1-12 years). The etiology of the A-V block was surgical in 13 cases, congenital in nine, and acquired in two. Twenty patients had symptoms of cerebrovascular insufficiency and four had congestive heart failure. To date, 18 of the 24 patients studied are alive and well. Death occurred in six patients, five of whom had complex congenital heart defects, and one of whom had Refsum's disease. Death probably was caused by complete heart block despite pacemaker treatment in four patients, and congestive heart failure in two. In 18 of the 24 children with disabling complete A-V block, pacemaker therapy provided relief of symptoms and prolonged life.     

Complete heart block as a consequence of atriondal discontinuity.

We have recently studied a case of complete heart block in which there was considerable difficulty in deciding whether it was of congenital or acquired origin. This was because the heart block was first discovered at the age of 2 years in the course of acute diphtheria. Though diphtheritic infections are known to affect the cardiac conduction system, authenticated cases of post-diphtheritic block persisting after the infection are rare, and, furthermore, histopathological study in this case revealed discontinuity between the atrial tissues and the more peripheral parts of the atrioventricular conduction tissues. This has been more commonly observed in congenital cases of complete heart block and it has been postulated on theoretical grounds that this could be thebasis for congenital heart block; on the other hand, it has been noted in a single casethought to be of acquired origin. Review of the evidence available failed to allow accurate classification of the case into either congenital or acquired categories. Thenormal, segmental development of the atrioventricular node, each segment being of different embryological origin, is discussed and the case presented is understandable in thelight of this.     

Complete heart block in HLA B27 associated disease. Electrophysiological and clinical characteristics.

A genetic predisposition associated with HLA B27 for developing complete heart block with or without clinical or radiological signs of associated rheumatic disease has recently been found. In this electrophysiological study of 12 patients with spontaneous complete heart block and HLA B27 associated disease, of whom eight had ankylosing spondylitis, 10 had suprahisian second or third degree atrioventricular block (eight spontaneously and two during atrial pacing at rates below 90 impulses per minute) and one infrahisian block. One patient with narrow QRS complexes during complete heart block three months earlier had normal findings. Three patients also had sinus node malfunction and six had fascicular or bundle branch block. In HLA B27 associated disease the atrioventricular block seems to be preferentially located in the atrioventricular node, although the conduction system may be widely affected. The findings in this study indicate a further cause of high degree atrioventricular block with a predominantly suprahisian location in addition to acute inferior myocardial infarction, digitalis intoxication, and "congenital" heart block.     

Signs of first-degree heart block occur in one-third of fetuses of pregnant women with anti-SSA/Ro 52-kd antibodies

OBJECTIVE: To prospectively investigate the development of fetal heart block in anti-SSA/Ro 52-kd-positive women, and to evaluate the usefulness of serial Doppler echocardiography in detecting early signs of congenital heart block. METHODS: Twenty-four women with anti-SSA/Ro 52-kd antibodies and consequently increased risk for fetal heart block were followed up weekly, between 18 and 24 weeks of gestation, with two Doppler echocardiographic methods designed to estimate the time delay between hemodynamic events caused by atrial and ventricular depolarizations. Two hundred eighty-four women with normal pregnancies served as controls. Anti-Ro 52-kd, anti-Ro 60-kd, and anti-La antibodies were investigated by immunoblotting and enzyme-linked immunosorbent assay using recombinant proteins. RESULTS: In anti-Ro 52-kd-positive women, fetal atrioventricular (AV) time intervals were longer and heart rates were slightly lower compared with those in controls. Eight of 24 fetuses had signs of first-degree block. One of these fetuses had progression to complete block, and another showed recovery from second-degree block to first-degree block with betamethasone treatment. In the remaining 6 fetuses, spontaneous normalization occurred before or shortly after birth. Fetuses with normal AV time intervals at 18-24 weeks had normal electrocardiographic results at birth. CONCLUSION: Anti-Ro 52-kd-positive pregnant women frequently carry fetuses with Doppler echocardiographic signs of first-degree AV block. These blocks revert spontaneously in the majority of fetuses, but progression to a more severe degree of block may occur in some. Serial Doppler echocardiographic measurement of AV time intervals is suggested as a useful method for surveillance of these high-risk pregnancies.     

Congenital atrioventricular block and Wolff-Parkinson-White Syndrome

We report the case of a patient followed since childhood for congenital complete atrioventricular block. At 28 years of age, atrioventricular conduction through an accessory pathway with long conduction times was detected. Periods of atrioventricular conduction alternated with periods of atrioventricular block. Sinus tachycardia and 1:1 exclusive conduction through the accessory pathway developed with increased sympathic activity (exercise, isoproterenol infusion). We discuss the special features of this case.     

His Bundle pacing for congenital complete AV block: An attempt to fix a broken heart?

Congenital complete atrioventricular block (CCAVB) is usually due to failure of atrioventricular nodal conduction with preservation of the His‐Purkinje system. Most patients with CCAVB ultimately require pacemaker therapy to restore physiologic heart rates, dealing with the detrimental effects of chronic right ventricular (RV) pacing on cardiac structure and function. The ideal stimulation pattern aims to mimic the normal conduction to restore electromechanical coupling, preventing the harmful effects of lack of atrioventricular and inter‐intraventricular synchrony. This can be done through conduction system pacing. Using His bundle pacing (HBP) for cardiac resynchronization therapy in two complete congenital atrioventricular block patients, we have reported better exercise tolerance and echocardiographic improvements related to reversible left ventricular dysfunction that can be corrected by restoration of the normal activation pathway via the His‐Purkinje network.     

Left isomerism and complete atrioventricular block: A report of six cases

Six children, aged 12 days to 13 years, with left isomerism and complete atrioventricular (A-V) block are presented. In all six patients the diagnosis of left isomerism was suggested by an interrupted inferior vena cava found during cardiac catheterization and angiocardiography;four patients had complex heart disease consisting of endocardial cushion defect, five had a common atrium, three had pulmonary stenosis, three had patent ductus arteriosus and two had dextrocardia. Further anatomic abnormalities included situs inversus of the viscera (four patients) as well as partial malrotation of the bowel. Of the six patients, four had congenital complete A-V block, whereas the remaining two had A-V conduction disturbances documented during early infancy that progressed to complete A-V block later in life. All six patients required pacemaker implantation and five of the six patients died. This report discusses the clinical presentation of complete A-V block and left isomerism and reviews the literature.     

Finding the “PR‐fect” Solution: What Is the Best Tool to Measure Fetal Cardiac PR Intervals for the Detection and Possible Treatment of Early Conduction Disease?

In the absence of structural heart disease, the great majority of cases with complete congenital heart block will be associated with the maternal autoantibodies directed to components of the SSA/Ro—SSB/La ribonucleoprotein complex. Usually presenting in fetal life before 26 weeks' gestation, once third‐degree (complete) heart block develops, it is irreversible. Therefore, investigators over the past several years have attempted to predict which fetuses will be at risk for advanced conduction abnormalities by identifying a biomarker for less severe or incomplete disease, in this case, PR interval prolongation or first‐degree atrioventricular block. In this state‐of‐the‐art review, we critically analyze the various approaches to defining PR interval prolongation in the fetus, and then analyze several clinical trials that have attempted to address the question of whether complete heart block can be predicted and/or prevented. We find that, first and foremost, definitions of first‐degree atrioventricular block vary but that the techniques themselves are all similarly valid and reliable. Nevertheless, the task of predicting those fetuses at risk, and who are therefore candidates for treatment, remains challenging. Of concern, despite anecdotal evidence, there is currently no conclusive proof that a prolonged PR interval predicts complete heart block.     

Double discordance with ventricular septal defect and pulmonary artery hypertension. A study of 21 cases

This paper reports a retrospective study of 21 children with atrioventricular and ventriculo-arterial discordance, or double discordance, associated with a large ventricular septal defect responsible for pulmonary hypertension. Other associated congenital defects were: atrioventricular block (5 cases), coarctation of the aorta with neonatal cardiac failure (6 cases), tricuspid valve malformations responsible for significant tricuspid regurgitation (11 cases) and right ventricular hypoplasia (1 case). Two children died before any therapeutic intervention, one from syncope related to atrioventricular block and the other after a decision of therapeutic abstention. Three children underwent total correction with one good result (the only case of situs inversus), one late death and one lost to follow-up. The majority of patients (n = 16) underwent initial palliative surgery consisting in pulmonary artery banding occasionally associated with reconstruction of the aortic arch: there was no early mortality but there were 2 late deaths. Of the 14 survivors, 6 are well after a mean follow-up period of 31 months. Eight underwent open heart surgery with 1 operative death, 6 post-operative complete atrioventricular blocks requiring cardiac pacing and 5 poor results due to aggravation or secondary tricuspid regurgitation leading to 1 cardiac transplantation (death) and 2 reoperations for valvular surgery (1 plasty and 1 tricuspid valve replacement). The overall results of this series are poor: high mortality (33 per cent) and equally high morbidity when direct surgery is undertaken. Two major complications are observed: complete atrioventricular block (55 per cent) and regurgitation of the systemic atrioventricular valve (45 per cent), both of which often necessitate invalidating complementary procedures.(ABSTRACT TRUNCATED AT 250 WORDS)     

Congenital and surgical atrioventricular block within the His bundle

In three patients with congenital heart disease the site of atrioventricular (A-V) block was localized within the His bundle with the aid of His bundle electrograms. In one patient with first degree A-V block and normal QRS configuration, electrophysiologic studies revealed “split” His potentials. The other two patients had complete A-V block, and their His bundle electrograms revealed His spikes both proximal and distal to the site of block. One of the two patients, who had a pattern of left bundle branch block in the electrocardiogram, had surgically induced complete A-V block after repair of an ostium primum atrial septal defect. The other patient with congenital A-V block had a narrow QRS complex and, in addition to complete block within the His bundle, prolonged A-V nodal conduction time but no associated cardiac anomaly. Both patients with complete heart block required pacemaker insertion.

The natural history of intra-His bundle block is not known, and it is difficult to recommend appropriate therapy. More electrophysiologic studies are needed in patients with A-V block to determine the prognostic significance of such block or conduction delay in the His bundle.     

Severe Left Atrioventricular Valve Regurgitation Due to Discontinuity between the Leaflets of the Aortic and Left Atrioventricular Valves in a Patient with Endocardial Cushion Defect: A Rare Case Report

Discontinuities between the leaflets of the aortic and left atrioventricular valves are uncommon congenital malformations. The anomaly may be discovered during surgery without preoperative diagnosis. It represents a spectrum of anomalies that result from interruption of the normal development of the endocardial cushions during the fetal life. We describe a rare case of Down syndrome with transient complete atrioventricular block and discontinuity between the leaflets of the aortic and left atrioventricular valves without intervening fibrous band, leading to separation and detachment between them. It caused severe eccentric jet of regurgitation originated from left ventricular outflow tract and base of anterior leaflet of left atrioventricular valve into the left atrium. He underwent cardiopulmonary bypass, and the defect between left atrioventricular valve and aortic annuli was sewn. Permanent epicardial pacing was inserted during cardiac surgery. To the best of our knowledge, such a case has not been previously reported in the literature.     

Early diastolic clicks after the Fontan procedure for double inlet left ventricle: anatomical and physiological correlates

M mode echocardiograms and simultaneous phonocardiograms were recorded in four patients with early diastolic clicks on auscultation. All had double inlet left ventricle and had undergone the Fontan procedure with closure of the right atrioventricular valve orifice by an artificial patch. The phonocardiogram confirmed a high frequency sound occurring 60-90 ms after aortic valve closure and coinciding with the time of maximal excursion of the atrioventricular valve patch towards the ventricular mass. One patient had coexisting congenital complete heart block. The M mode echocardiogram showed "reversed" motion of the patch towards the right atrium during atrial contraction. Doppler flow studies showed that coincident with this motion there was forward flow in the pulmonary artery with augmentation when atrial contraction coincided with ventricular systole. The early diastolic click in these patients was explained by abrupt cessation of the motion of the atrioventricular valve patch towards the ventricular mass in early diastole. In one patient atrial contraction led to a reversal of this motion and was associated with forward flow in the pulmonary artery.