Congenital complete heart block. A classification and experience with 18 patients

Natural history of congenital complete atrioventricular block

An update of studies on the natural history of congenital complete AV block is presented. A risk for heart failure, syncope, and sudden death is present at any age including fetal life. Unfavorable prognostic signs in utero are low and decreasing ventricular rate (VR), hydrops, AV valve regurgitation, and low aortic flow velocity. Indications for pacing in infancy are congestive heart failure, ventricular rate < 55 beats/min in isolated block and < 65 beats/min with associated disease, prolonged OTc, syncope attacks, frequent ventricular ectopic beats, and alternating ventricular pacemakers. Indications for immediate pacing in childhood and adult life are syncope, presyncope, VR rates lower than median for age, periods of junctional exit block, prolongation of QTc and mitral regurgitation, and change of ventricular pacemaker. Pacing is recommended to all patients older than 15 years.

Isolated congenital complete atrioventricular block in adult life. A prospective study

BACKGROUND

The prognosis of congenital complete atrioventricular block (CCHB) is usually considered favorable in adults. This belief is based on studies comprising a limited number of patients and with rather short observation times. In the present study, the natural history of the disease was investigated by a prospective follow-up through decades of adult life of patients with a large group having well-defined CCHB without structural heart disease.

METHODS AND RESULTS

The diagnostic criteria of CCHB proposed by Yater were applied. Patients registered as having CCHB in 1964, supplemented by younger patients all without symptoms during their first 15 years of life, were selected. The study was limited to patients with isolated, complete, permanent block. An interview was conducted with all patients and clinical follow-up data obtained. There were finally 102 patients, 61 women and 41 men. In November 1994, the time of observation, after the age of 15 years in survivors, was between 7 and 30 years. The mean age at follow-up or at death was 38 years, median age 37 years, and range 16 to 66 years. Stokes-Adams (SA) attacks occurred in 27 patients, in 8 with a fatal outcome. The first attack was fatal in 6 of these 8 patients. Nineteen survived and a pacemaker (PM) was implanted thereafter. Another 8 patients received a PM because of repeated fainting spells, and 27 others have had a PM implanted for other reasons such as fatigue, effort dyspnea, dizziness, ectopies during exercise tests, mitral regurgitation, and a low ventricular rate (VR). VR decreased with age, with a mean rate at 15 years of 46 beats per minute (bpm), at 16 to 20 years of 43 bpm, at 21 to 30 years of 41 bpm, at 31 to 40 years of 40 bpm, and after 40 years of age of 39 bpm. SA attacks occurred in all 7 patients with prolonged QTc time. Low VR at rest or at work, presence of bundle-branch block pattern, low working capacity, and ectopies at rest and/or during effort were not statistically significant risk factors. SA attacks occurred in 6 patients without any of these signs. Mitral regurgitation developed in 16 patients and 4 died. A PM reduced the risk of death. A change to a lower degree of block occurred in 6 patients.

CONCLUSIONS

Prophylactic PM treatment is recommended even for symptom-free adults with CCHB because of the high incidence of unpredictable SA attacks with considerable mortality from first attacks, a gradually decreasing VR, significant morbidity, and a high incidence of "acquired" mitral insufficiency.

Congenital complete heart block in patients without anatomic cardiac defects

Forty-three patients with congenital complete heart block and an otherwise structurally normal heart were reviewed in an effort to better define the profile of an anatomically homogenous group and to identify factors that may predict the need for pacing. Fourteen patients (32%) developed "symptoms" during follow-up, including two with out-of-hospital cardiac arrest. Heart rate on electrocardiogram or Holter monitor did not clearly distinguish this subgroup. The presence of alternate "risk factors," such as atrial enlargement seen on electrocardiogram, cardiomegaly seen on x-ray film, or prolonged QT interval were independent predictors of symptoms and poor outcome (p less than 0.05). Ventricular ectopy determined on Holter monitoring was also common among the symptomatic group, although this finding was inconsistent. Prophylactic pacing is indicated in select patients with congenital complete heart block and otherwise normal anatomy. Surveillance for rick factors beyond rate criteria alone may refine this selection process.

Pacemakers in children: an update

This report reviews recent pacemaker technological advances as they apply to infants, children, and adolescents. Indications for pacemaker implantation in children have evolved since the 1984 Joint Task Force Guidelines. Recent data show that pacemaker implantation should be strongly considered in patients who have (1) asymptomatic congenital complete AV block with a mean heart rate less than 50 beats/min or other evidence of junctional instability; (2) congenital AV block with long QT interval; or (3) congenital long QT syndrome with bradyarrhythmias, or when conventional beta-blocker therapy is unsuccessful. Permanent pacemaker implantation is not necessarily an effective prophylactic measure against sudden death in patients following their operation who are receiving drug therapy for atrial tachyarrhythmias, and so is not absolutely indicated. New developments in lead technology have made transvenous lead systems more feasible for pediatric use. Because epicardial leads are required for small infants and for cosmetic reasons in some older children, design improvements are needed to enhance epicardial lead performance. Rate-responsive pacing is an acceptable alternative to dual-chamber pacing for augmenting exercise tolerance, and for children with sinus node dysfunction it is the preferred pacing mode. Pacemakers with automatic antitachycardia capabilities and with noninvasive electrophysiology features are valuable in children with atrial tachyarrhythmias. New data suggest that chronic atrial pacing also may be effective in controlling atrial tachyarrhythmias. New developments in pacemaker systems for the young parallel those for the older population, but differences between adult and pediatric patients demand ongoing increased participation by pediatric cardiologists.

Fetal and neonatal congenital complete heart block

Fifteen cases of congenital complete heart block were diagnosed in utero or at birth, over a nine-year period. Six cases were confirmed by fetal echocardiography between 22 and 36 weeks of gestation. Two cases were treated in utero for cardiac failure, and serial ultrasonography was used to monitor the progress. Structural heart disease was present in seven (47%) infants; in four of these infants the defect was a corrected transposition of the great arteries. Ventricular pacing was required in seven patients--four infants with anatomically-normal hearts and three infants with associated structural heart disease. Eight children did not require permanent pacing, and remained well after a mean follow-up period of 23 months (range, one to 72 months). The mortality was highest in those patients with structural heart disease, three of whom died as neonates. Only one baby died with an anatomically-normal heart. Antinuclear antibodies were present in the mothers of seven of the eight infants who were born with a structurally-normal heart. Four mothers either had pre-existing connective-tissue disease or had developed manifestations of such disease subsequent to pregnancy. Of this group, all the women were antibody-seropositive to the nuclear antigen SS-A during pregnancy. Mothers of three infants had antinuclear antibodies in low titres, were seronegative for antibody to SS-A and remained free of the manifestations of connective-tissue disease. Six of the seven most-recent cases have been diagnosed in utero, which confirms a trend towards the more-frequent prenatal diagnosis of congenital heart disease as a result of the increased use of fetal monitoring and ultrasonography.

Congenital complete atrioventricular block: clinical and electrophysiologic predictors of need for pacemaker insertion

Because of initial Adams-Stokes attack in the patient with congenital complete atrioventricular (A-V) block may sometimes prove fatal, there is a need to be able to identify the patient at great risk of having such attacks. Twenty-four children with congenital complete A-V block were followed up for 1 to 19 years to determine the efficacy of current methods of predicting risk for Adams-Stokes syncope and the usefulness of pacemaker therapy in relieving symptoms. The heart rate at rest, configuration of surface electrocardiographic complexes, data obtained during intracardiac electrophysiologic study and response to graded treadmill exercise testing were compared in children with and without syncope. One or more Adams-Stokes episodes were experienced by eight children, one of whom died. Only a persistent heart rate at rest of 50 beats/min or less demonstrated any significant (probability [p] less than 0.01) correlation with the incidence of syncope. Intracardiac electrophysiologic study was of little benefit because of site of block did not correlate with syncope. Although the increase in heart rate during treadmill exercise testing showed no correlation with prevalence of syncope or location of block, exercise-induced ventricular ectopic beats may have predictive value in older children and young adults. Ventricular pacemakers were implanted in 10 children. Each child was asymptomatic over a 1 to 10 year follow-up period. Because extreme bradycardia may contribute to the prevalence of Adams- Stokes attacks in children with congenital complete A-V block, careful evaluation of heart rate at rest may be an effective means of differentiating patients at risk of syncope. Pacemaker therapy is a feasible and effective method of treatment in young children and relieves symptoms

Lack of connection between the atria and the peripheral conduction system in a case of corrected transposition with congenital atrioventricular block

This is the first documented histologic study of the heart of a patient with corrected transposition of the great vessels and congenital atrioventricular (A-V) block with no connection between the atria and an anterior type of peripheral conduction system. Musculature in the superior (anterior) walls of both atria was absent, as was the anterior A-V node. The peripheral conduction system began with the bundle of His. In place of the absent atrial musculature, fibrosis and calcification were present. The relation of laboratory evidence of connective tissue dyscrasia in the mother to the congenital A-V block in the child is discussed.

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.

Long-term follow-up of two infants with an implanted cardiac pacemaker

The clinical course of two patients with congenital heart block who had pacemaker implantation at age 7 and 8 months, respectively, is reviewed. One patient at age 10 years has had nine pulse generators inserted; the other has had six implantations, the most recent a lithium iodine pacemaker, during 8 1/2 years of observation. Both patients have shown normal physical development and emotional maturation despite multiple hospitalizations and pacemaker replacements, thus demonstrating that electrical pacing, initiated in infancy, can be maintained through childhood without adverse effects.

Bundle of His electrograms in congenital corrected transposition of the great arteries. A study of two adult cases

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