Congenital Complete Atrioventricular Block Research Articles

Left Ventricular Function After Left Ventriculotomy for Surgical Treatment of Multiple Muscular Ventricular Septal Defects

Optimal management of muscular ventricular septal defects (MVSD) is still not determined in the current era. Moreover, long-term left ventricular function after closure of MVSD is not well known. Thus, we investigated surgical outcomes including long-term left ventricular function after closure of MVSD through left ventriculotomy. We conducted a retrospective review of medical records of 20 children who underwent MVSD closure between March 1993 and August 2010. There were 10 boys (50%) and 10 girls (50%). Patient age ranged from 1.6 to 103.4 months (median, 26.4 months), and body weight from 2.8 to 31.5 kg (median, 11.9 kg). Electrocardiogram results were normal sinus rhythm in all except 1 patient with congenital complete atrioventricular block. There were 16 patients who previously had palliative pulmonary artery banding procedures before closure of MVSD. There were 13 patients (65%) with Swiss-cheese type VSD. There was 1 hospital death of a patient with congenital complete atrioventricular block with pacemaker malfunction (5%). There was 1 late death of a patient with del 22q with adenoviral pneumonia. There was no reoperation. Median follow-up duration was 85.9 months (range, 4.7 to 166.7). The location of MVSD was apical portion in 10 patients (50%) and midtrabecular portion in 9 patients (45%). There were 6 Dacron patch closures and 13 direct closures of MVSD through left ventriculotomy. There was no complete atrioventricular block. Last follow-up echocardiographic data showed normal ejection fraction with 65.2% ± 8.2% after closure of MVSDs. There was no leakage in 8 patients; 11 patients had insignificant leakage, which disappeared spontaneously in 4 patients 17.9 months (median value) after operation. Our acceptable long-term results of left ventricular function after left ventriculotomy proved that this technique might be a viable option in the management of MVSD.

Relation of Maternal Anti-Ro/La Antibodies to Aortic Dilation in Patients With Congenital Complete Heart Block

An association between congenital complete atrioventricular block (cCAVB) and aortic dilation during childhood has recently been reported. We sought to further explore this relation with particular emphasis on the natural history of aortic abnormalities over time. The relation of maternal anti-Ro/La antibody status to the aortic size of children affected with cCAVB was also assessed. The patients were evaluated longitudinally with serial echocardiography. During a 15-year period, 62 patients at our institution were diagnosed with cCAVB, of whom 40% were exposed to maternal autoimmune antibodies and 35% were not. The antibody status in the remaining patients was unknown. The patients underwent 9.3 ± 6.5 echocardiograms during the follow-up period. Dilation of the ascending aorta, defined as a z score >2.0, was present on the initial echocardiogram in all patients exposed to maternal antibodies and persisted during long-term follow-up in 96% of these patients. In contrast, 5% and 10% of patients without exposure to maternal autoimmune antibodies had aortic dilation on the initial and follow-up studies, respectively (p <0.001 and p <0.001, respectively). In conclusion, patients with autoimmune-mediated cCAVB merit periodic echocardiographic monitoring into adulthood to assess persistent or progressive aortic dilation and its attendant complications.

Prolongation of the Atrioventricular Conduction in Fetuses Exposed to Maternal Anti-Ro/SSA and Anti-La/SSB Antibodies Did Not Predict Progressive Heart Block: A Prospective Observational Study on the Effects of Maternal Antibodies on 165 Fetuses

We prospectively examined the prevalence and outcome of untreated fetal atrioventricular (AV) prolongation in the presence of maternal anti-Ro antibodies. It has been suggested that antibody-mediated congenital complete atrioventricular block (CAVB) may be preventable if detected and treated early when low-grade block is present. With this rationale in mind, dexamethasone has been advocated by others to treat prolonged fetal AV conduction >2 z-scores, consistent with first-degree heart block. Between July 2003 and June 2009, 165 fetuses of 142 anti-Ro/La antibody-positive women were referred to our center for serial echocardiography. Our protocol included weekly evaluation of the fetal AV conduction between 19 (range 17 to 23) and 24 (range 23 to 35) gestational weeks. AV times were compared with institutional reference data and with post-natal electrocardiograms. Of 150 fetuses with persistently normal AV conduction throughout the observation period, a diagnosis of CAVB was subsequently made in 1 at 28 weeks, after the serial evaluation had ended. Of 15 untreated fetuses either with AV prolongation between 2 and 6 z-scores or with type 1 second-degree block, progressive heart block developed in none of them. Three of these 15 fetuses (20%) had a neonatal diagnosis of first-degree block that spontaneously resolved (n = 2) or has not progressed (n = 1) on follow-up examinations. No other cardiac complications were detected. Fetal AV prolongation did not predict progressive heart block to birth. Our findings question the rationale of a management strategy that relies on the early identification and treatment of fetal AV prolongation to prevent CAVB.

Noninvasive Measurement of Atrial Contribution to the Cardiac Output in Children and Adolescents With Congenital Complete Atrioventricular Block Treated With Dual-Chamber Pacemakers

The contribution of atrial contraction to cardiac output (CO) has been the subject of extensive research but has yet to be quantified adequately in children and adolescents. Patients with third-degree atrioventricular (AV) block treated with pacemakers (PMs) are ideal candidates to assess the atrial contribution to CO by repeated measurements in single-chamber pacing mode (VVIR) and dual-chamber pacing mode (DDD/VDD). Hemodynamic measurements in children are often complicated by technical restrictions, but more recently a noninvasive method involving inert gas rebreathing has become available, which is an excellent tool for this age group. We examined 10 patients (6 female patients, mean age 14.5 ± 2.5 years, range 11 to 18) with congenital complete AV block treated with dual-chamber PM. Using an inert gas rebreathing device (Innocor) we measured CO in DDD/VDD with optimized AV delays. Devices were subsequently set to VVIR with matched heart rates and after 20 minutes the CO measurement was repeated. Mean CO of 6.4 ± 1.8 L/min was significantly higher in DDD/VDD than in VVIR, where it averaged 5.2 ± 1.4 L/min (p <0.001). Fractional increase of CO gained through sequential ventricular contraction was 18% (p <0.001). In VVIR, 8 patients reported PM-related symptoms. In conclusion, our data strongly suggest that pediatric patients with congenital complete AV block may benefit from AV synchrony with respect to hemodynamics and tolerability. Therefore, preferred use of DDD/VDD with optimized AV conduction delays should be considered.

Ventricular Resynchronization by Implementation of Direct His Bundle Pacing in a Patient with Congenital Complete AV Block and Newly Diagnosed Cardiomyopathy

Congenital complete atrioventricular block (CCAVB) is usually due to failure of AV nodal conduction with preservation of the His Purkinje system, typically present at birth. While most patients with CCAVB ultimately require pacemaker therapy to restore physiologic heart rates, recent studies have suggested that chronic right ventricular (RV) pacing in patients with CCAVB can have detrimental effects on cardiac structure and function, and may account for a 7-10% incidence of congestive heart failure in these patients. Since the His Purkinje system is preserved in CCAVB, this patient population could be uniquely well served by direct His bundle pacing (DHBP) which would be expected to restore physiologic activation of both ventricles. We present a case of a young woman who presented with RV pacing-induced cardiomyopathy who responded dramatically to DHBP.

Emergent Caesarean section in parturient with congenital complete atrioventricular block

Maternal complete atrioventricular block undergoing emergent operative procedure under general anaesthesia should always be managed with intraoperative temporary pacing.

Noninvasive Cardiac Output Determination for Children by the Inert Gas-Rebreathing Method

Standard methods for determination of cardiac output (CO) are either invasive or technically demanding. Measurement of CO by the inert gas-rebreathing (IGR) method, applied successfully in adults, uses a low-concentration mixture of an inert and a blood-soluble gas, respectively. This study tested the feasibility of this method for determining CO during exercise for pediatric patients with complete congenital atrioventricular block (CCAVB) stimulated with a VVI pacemaker. In this study, 5 CCAVB patients (age 9.2-17.4 years) were compared with 10 healthy age-matched boys and girls. Testing was performed with the Innocor system. The patients were instructed to breathe the test gas from a closed system. Pulmonary blood flow was calculated according to the washout of the soluble gas component. During standardized treadmill testing, CO was determined at three defined levels. The CO measurements were successful for all the study participants. The patients reached a lower peak CO than the control subjects (5.9 l/min/m(2) vs 7.3 [boys] and 7.2 [girls]). The stroke volume increase under exercise also was reduced in the patients compared with the control subjects. The feasibility of the IGR method for exercise CO testing in children was documented. Application of the IGR method for children requires careful instruction of the patients and appears restricted to subjects older than 8 years. The method offers new insights into mechanisms of cardiovascular adaptation in children with congenital heart disease.

A Newborn with Congenital Complete Atrioventricular Block, Lissencephaly, and Skeletal Abnormalities: A Case of Suspected Cytomegalovirus Infection

We present a case of congenital complete atrioventricular block in a preterm microcephalic male with multiple additional congenital anomalies, including spinal and rib abnormalities. The heart was structurally normal, and maternal tests for autoimmune disorders were negative. The brain had an immature lissencephalic appearance, suggestive of an insult early in gestation. Genetic testing was normal, virtually excluding chromosomal disorders that are known to cause lissencephaly. Viral studies were suggestive of cytomegalovirus infection during early gestation, and we believe that the patient's clinical presentation was most likely the result of an early cytomegalovirus infection. The finding of complete atrioventricular block in a patient with presumed cytomegalovirus infection would represent a very rare complication. "Isolated" complete atrioventricular block in a fetus should be considered an incentive for an extensive work-up in search for a possible etiology, rather than accepted as a final diagnosis.

Determinants of early dilated cardiomyopathy in neonates with congenital complete atrioventricular block

Dilated cardiomyopathy (DCM) can occur in infants with congenital complete atrioventricular block (CCAVB) treated by permanent pacemaker (PM), even without other congenital heart defects. The objective is to find the risk factors of this complication. Retrospective analysis of a single-centre experience. Since 1992, 25 patients, aged 25 (1-355) days [median (range)], with normal ejection fraction (EF), underwent PM implantation (13 DDD, 12 VVIR) with an RV-pacing site. Follow-up was 4 (0.3-16) years. DCM occurred after 4 (3-23) months in eight patients (32%). Univariate analysis identified the following risk factors: younger age at implantation [5 (1-85) days vs. 90 (1-355) P = 0.007], a broad QRS (50 vs. 18% P = 0.03), prolonged QTc at implantation (63 vs. 0%, P = 0.001), and greater duration of heart rate >160 bpm during the first month after implantation (18 vs. 2%, P = 0.03). By multivariate analysis prolonged QTc was the only significant risk factor for DCM (hazard ratio: 23, P < 0.001, 95% confidence interval: 4-128). One patient died of heart failure, one was lost to follow up, and two were compensated on anticongestive therapy. EF normalized in four patients after resynchronization therapy (two patients), normalization of AV conduction or changing pacing mode to allow predominant narrow QRS junctional rhythm (one patient each). Neonates with CCAVB without other congenital heart defects and prolonged QTc are at high risk for DCM possibly due to electromechanical dyssynchrony induced by high-rate RV pacing. In patients in whom RV pacing was discontinued, EF became normal.

The Benefits of Transplacental Treatment of Isolated Congenital Complete Heart Block Associated with Maternal Anti-Ro / SSA Antibodies: A Review

Isolated congenital complete atrio-ventricular block (CAVB) is associated with the transplacental passage of maternal autoantibodies directed to foetal Ro/SSA ribonucleoproteins. Their interactions most likely trigger the inflammation of the atrio-ventricular node and the myocardium in susceptible foetuses. The inflamed tissues may then heal with fibrosis that may cause heart block, endocardial fibroelastosis, and dilated cardiomyopathy. CAVB, the most common cardiac complication, typically develops between 18 and 24 gestational weeks. Untreated, the condition carries a significant mortality risk as the foetus needs to overcome the sudden drop in ventricular rate, the loss of normal atrial systolic contribution to ventricular filling, and perhaps concomitant myocardial inflammation and fibrosis. The rationale to treat a foetus at the stage of CAVB is primarily to mitigate myocardial inflammation and to augment foetal cardiac output. Maternal dexamethasone administration has been shown to improve incomplete foetal AV block, myocardial dysfunction, and cavity effusions. Beta-sympathomimetics may be useful to increase the foetal heart rate and myocardial contractility. Published data from our institution suggest an improved survival >90% if maternal high-dose dexamethasone was initiated at the time of CAVB detection and maintained during the pregnancy and if a beta-adrenergic drug was added at foetal heart rates below 55 beats/min. Despite the improvement in outcome, there is an ongoing debate about treatment-related risks. In this review, we will appraise the natural history of untreated CAVB, discuss currently available management options, and examine the results and risks of in-utero treatment of antibody-mediated CAVB.

Congenital Complete Atrioventricular Block Associated with QT Prolongation: Description of a Patient with an Unusual Outcome

The association of a complete atrioventricular block with long QT syndrome is relatively common and carries a high risk of torsades de pointes (TdP) and sudden death. It is probably due to a downregulation of potassium channel currents (I (Ks) and I (Kr)) that impairs ventricular repolarization, prolongs the QT interval and increases susceptibility to TdP, so it must be considered a channelopathy. This report describes a 6 year-old boy, with a complete atrioventricular block diagnosed at 5 months of age, who at the age of 1 year started having episodes of TdP associated with a prolonged QT interval. He was treated successfully with propranolol and with a pacemaker implant. At age 3 the complete atrioventricular block reversed spontaneously to a first degree atrioventricular block.

Cardiac Resynchronization Therapy for Left Ventricular Dysfunction Induced by Chronic Right Ventricular Pacing in a Child

Cardiac resynchronization therapy (CRT) has been proven its value in adult patients with congestive heart failure of low ejection fraction and wide QRS duration. Contrast to adult patients, CRT has been rarely applied for young patients. We report on a 9-yr-old boy with progressive left ventricular (LV) dilatation and dysfunction following chronic VVI pacemaker therapy for congenital complete atrioventricular block associated with maternal anti-SSA/Ro and SSB/La antibody. His LV dysfunction was improved after epicardially established CRT.

Muerte fetal anteparto y síndrome de Sjögren oculto

Sjögren's syndrome is an immunological disorder characterized by progressive lymphocyte destruction of exocrine glands and is often associated with autoimmune diseases. Anti-Ro/SSA and anti-La SSB antibodies have a high prevalence in Sjögren's syndrome and are closely associated with fetal loss, recurrent abortions, neonatal lupus, and congenital complete atrioventricular block and less frequently with fetal valvulopathy. We report a case of antepartum fetal death in a patient with occult Sjögren′s syndrome. This disease should be included in the study of antepartum fetal death, even in asymptomatic cases.

Pacemaker Upgrade Causing New-Onset Heart Failure in a Patient with Complete Congenital Atrioventricular Block

For infants with congenital complete atrioventricular block (CCAVB), the choice of pacing modalities is limited. Due to their size and surgical limitations, neonates typically start with an epicardial right ventricular pacing system, then upgrade to right-sided dual-chamber pacing once appropriate size is achieved. These modes are generally well tolerated. However, the reported case involved a patient with CCAVB who paradoxically experienced congestive heart failure after upgrading to a dual-chamber system, a theoretically superior pacing modality. With conversion to biventricular pacing, a relatively new modality for adults with very little pediatric experience to date, the patient's symptoms dramatically improved.

Permanent Endovenous Pediatric Pacing: Absence of Lead Failure—20 Years Follow‐Up Study

The aim of the study was to analyze endovenous pacing lead survival in pediatric population implanted by cephalic cut down, or by axillary vein puncture. All implantations were performed in total endotracheal anesthesia, by the same surgeon. Implantations of ventricular leads were performed by cephalic vein cut down or by external jugular vein preparation. In dual-chamber pacing, atrial leads were implanted via cephalic vein (along with ventricular lead), by axillary vein puncture or via external jugular vein. All implanted leads were secured by resorbable suture. Over the 20-year follow-up period, 105 children of 5.7 years average age (range 1 day-15 years) were implanted with a permanent endovenous pacing system for congenital or postsurgical complete atrioventricular block or sinus node disease. Within the group, 27 patients (25.7%) weighed less than 10 kg on implantation. A total of 121 endovenous leads were implanted. All ventricular leads were with a passive fixation mechanism, and most of them unipolar (87.6%) and steroid eluting (94.2%). Leads implanted in atrial position were 82% bipolar, predominantly with active fixation (94%), and all steroid eluting. The most frequently used mode of stimulation was VVIR (66.6%). No acute or chronic lead displacement, exit block, sensing problem, lead conductor fracture, insulation defect or infections were observed during the total follow-up of 709 pacing years (average 6.9, range 0-20 years). Implantation of the endovenous leads by preparation of the cephalic or puncture of the axillary vein, with lead fixation by resorbable suture represents a method of choice.

Outcome of Prenatally Diagnosed Isolated Congenital Complete Atrioventricular Block Treated with Transplacental Betamethasone or Ritodrine Therapy

The effectiveness of transplacental drug therapy for prenatally diagnosed isolated congenital complete atrioventricular block (CCAVB) is controversial. Nine cases of prenatal isolated CCAVB were treated from 2002 to 2007. Ritodrine was administered transplacentally to all fetuses and betamethasone to those whose mothers tested positive for maternal anti-SSA/Ro antibodies. Six of the nine patients had an anti-SSA/Ro-positive mother and received transplacental betamethasone 4 mg/day at a median gestational age of 28 weeks (range, 24-31 weeks). No patients exhibited an improvement in the degrees of complete heart block, and one patient died in utero. No serious adverse events occurred. After the mean follow-up period of 1.7 +/- 1.3 years, all five patients treated with transplacental betamethasone experienced a good cardiac function, whereas one of the three patients not treated with transplacental betamethasone experienced cardiomyopathy and died at the age of 4 months. Pacemaker implantation was required for seven of the eight live-born infants. Transplacental betamethasone therapy for the patients with isolated CCAVB neither improved the degree of atrioventricular block nor decreased the rate of patients requiring pacemaker implantation, but it probably reduced the risk for the development of myocardial disease.

Long-Term Outcome of Isolated Congenital Complete Atrioventricular Block Pacing Since Neonatal Period Experience at a Single Japanese Institution

Few investigators have examined the outcome of patients with isolated congenital complete atrioventricular block (CCAVB) paced from the neonatal period. The present study follows the clinical course and describes the outcome of patients who have been paced with CCAVB since they were neonates. The medical records of 20 patients with CCAVB paced as neonates between 1981 and 2006 were retrospectively studied and reviewed; 18 were diagnosed in utero and 2 at birth. SS-A antibodies were detected in 9 of 14 (64%) mothers tested. The median age at follow-up was 5.6 years (range, 2 days to 21.9 years). Three (15%) of the early neonates died and 3 (15%) died later: 2 from dilated cardiomyopathy (DCM) and 1 from pneumonia. The total mortality rate was 30%. The cumulative probability of survival at 10 years was 73%. Of the 14 survivors, 4 developed DCM, representing a total morbidity of 30%. The cumulative probability of freedom from DCM at 10 years was 59%. Patients with CCAVB who undergo pacing as neonates have high mortality and high morbidity because of DCM. Left ventricular pacing or resynchronization can benefit patients who develop DCM and left ventricular epicardial pacing is recommended for neonates with CCAVB.

Reversal of Pacing-Induced Heart Failure by Left Ventricular Apical Pacing

To the Editor: Children with congenital complete atrioventricular block often require lifelong pacemaker therapy. Although such therapy restores a normal heart rate, it also results in dyssynchrono...

Restoration of cardiac function by setting the ventricular pacing at a lower range in an infant with congenital complete atrioventricular block and dilated cardiomyopathy

Patients paced for congenital complete atrioventricular block are at risk of dilated cardiomyopathy. We report such an infant in whom the dilated cardiomyopathy resolved after adjusting the ventricular pacing range. The infant received an epicardial pacemaker soon after birth for the congenital complete atrioventricular block. He developed dilated cardiomyopathy 5 months after right ventricular pacing at 140 bpm, which is the mean physiological heart rate of the newborn and young infant. The cardiac function recovered gradually (left ventricular ejection fraction from 20% to 74%) after lowering the ventricular pacing rate to a range from 90 to 120 bpm. We suggest that pacing at heart rates that are within the mean physiological range may still be detrimental in young infants. Adjusting the pacing range may, at least in part, help to restore the ventricular function.

Longitudinal Echocardiographic Follow‐Up in Children with Congenital Complete Atrioventricular Block

Due to a low heart rate (HR) in children with congenital complete atrioventricular block (CCAVB), a larger stroke volume of the left ventricle (LV) may be expected. If so, end-diastolic (LVEDD) and end-systolic (LVESD) diameters may be enlarged and even dilated cardiomyopathy (DCM) may occur. The aim of this study was to answer the question if children with CCAVB develop LV dilatation. Furthermore, we investigated whether LV dilatation would decrease after pacing. We longitudinally evaluated echocardiographic data (LVEDD, LVESD, shortening fraction [SF]) in 36 children with CCAVB. Age at the first visit was 2.5 +/- 3.3 years (mean +/- SD); follow-up 10.6 +/- 7.3 years. Three children had DCM, already at 1st visit. LVEDD and LVESD Z scores in all children with CCAVB were larger than in normal controls (LVEDD Z score 1.38 +/- 1.80; LVESD Z score 0.64 +/- 1.35). Both Z scores were larger when HR was lower. Both Z scores increased over time in children who met criteria for pacing, but did not change in non-paced children. Physiologic pacing decreased both Z scores. SF of all children was normal and remained normal during follow-up (0.39 +/- 0.05 1st visit vs 0.39 +/- 0.06 last visit). We conclude that children with CCAVB have LV dilatation, which is progressive in children who met criteria for pacing. LV dilatation regressed by physiologic pacing. LV dilatation was larger when HR was lower. SF does not deteriorate over time. DCM occurs early in the disease and does not develop during childhood, not even in children with LV dilatation.