eMedicine Specialties > Pediatrics: Cardiac Disease and Critical Care Medicine > Cardiology

Atrioventricular Block, Third Degree, Congenital: Treatment & Medication

Author: Monesha Gupta, MD, MBBS, FAAP, FACC, Assistant Professor, Division of Pediatric Cardiology, University of Texas Medical School, Children's Memorial Hermann Hospital
Coauthor(s): Robert Murray Hamilton, MD, MSc, FRCPC, Section Head, Electrophysiology, Director, High-Risk Hereditary Heart Conditions Clinic, Labatt Family Heart Centre; Professor, Department of Pediatrics, Associate Scientist, Physiology and Experimental Medicine, The Hospital for Sick Children and Research Institute, University of Toronto, Canada
Contributor Information and Disclosures

Updated: Feb 2, 2009

Treatment

Medical Care

The medical care of congenital atrioventricular block (CAVB) is currently focused on identifying the optimal timing of pacemaker therapy to ensure a positive outcome. Additional care is aimed at identifying and treating the associated conditions that arise.

Little evidence suggests that the administration of steroids, immunoglobulins or the performance of plasmapheresis in the mother can reverse third-degree AV block. However, these therapies may be helpful in early first-degree and second-degree heart block and reducing associated myocardial dysfunction. Hopefully, with further understanding of the pathophysiology of CAVB, a preventive therapy will be identified.

Regular and close monitoring for heart block and transplacental therapy with fluorinated steroids (dexamethasone) and beta-sympthomimetics have been used by some centers with satisfactory results at the first evidence of heart block and bradycardia with hydrops, respectively. Prophylactic therapy is not indicated because these medications can have maternal and fetal side effects.

Therapy of hydrops fetalis can be challenging in utero and after birth. A staged approach with stabilizing the patient, draining the effusions, the use of intravenous inotropes (dopamine) and chronotropes (isoproterenol), and placing a pacemaker has shown some success.

Surgical Care

Symptoms referable to bradycardia are an indication for pacing in complete CAVB. Because severe symptoms (eg, syncope) occasionally arise suddenly or sudden cardiac death can occur, additional risk factors identified from monitoring have been recommended as indications for pacing.

Temporary pacing can be achieved transcutaneously, transesopheally, or transvenously.

Permanent pacemaker placement is eventually needed in most children with CAVB. Major criteria for pacing based on ECG or Holter monitoring include an average heart rate less than 50 bpm, a nighttime or sleeping average heart rate less than 45 bpm, or pauses secondary to atrioventricular block that are longer than 3 seconds. In the setting of borderline major criteria, other criteria that may influence the decision for timing of pacemaker implantation include cardiomegaly, a high atrial rate, junctional instability (eg, junctional exit block), a broad complex escape rhythm, diminished ventricular response to exercise, QT prolongation, and complex ventricular ectopy.

When criteria are met, surgical implantation of an epicardial pacemaker should be performed, with knowledge of the implications of pacing in children and recognition of the lifelong need for pacing and pacemaker lead access. Multiple backup pacing systems at the time of surgery (eg, temporary transvenous pacing, transthoracic pacing units) are helpful to avoid the extremes of bradycardia that may be associated with anesthesia and pacemaker surgery.

Venous obstruction, small patient size, and actual or potential right-left shunting are relative contraindications for transvenous pacing. Fortunately, epicardial pacing leads have greatly improved and allow for successful pacing system insertion under these conditions. Some centers are using neonatal endocardial pacing systems.

In children older than the neonatal period, an endocardial pacing with transvenous approach is possible. The risk of venous occlusion appears to correlate with the ratio of available transvenous lead body sizes and the patient's body surface area.1 Exceeding this ratio may lead to a high incidence of venous obstruction. In addition, imaging of the subclavian-innominate venous channels before pacemaker lead placement is helpful for transvenous lead placement. The course of the lead should be evaluated in 2 planes to avoid inadvertent lead placement into the foramen ovale, an unroofed left superior vena cava to coronary sinus, or left-sided circulation via the subclavian artery. Either a subcutaneous or subpectoral pocket may be formed inferior to the clavicle (see Pacemaker Therapy).

Consultations

The mother should consult with a rheumatologist to begin monitoring for possible autoimmune disease. Consultation with a rheumatologist is also advised for the infant, particularly if other manifestations of neonatal lupus erythematosus are present.

Genetic consultation is recommended for children with first-degree relatives with structural heart disease or those with storage disorder or cardiomyopathy.

Activity

Patients with permanent pacing systems should be restricted from activities that result in repeated intentional direct trauma to the pacemaker area (eg, martial arts). Patients with permanent pacing systems should be restricted from exposure to high magnetic fields, such as direct MRI exposure.

Medication

Intrauterine treatments used for congenital atrioventricular block (CAVB) include chronotropic agents, inotropic agents, steroids, and plasmapheresis.

In general, medications are not necessary in children with complete CAVB. Emergency use of chronotropic medications, with or without inotropic agents, may be helpful in fetuses and newborns with hydrops fetalis, congestive heart failure, or low cardiac output. Some investigators have suggested the use of immunosuppressive agents in fetuses and newborns to potentially slow or halt progressive CAVB in utero. This is currently being evaluated as a prospective study.

More on Atrioventricular Block, Third Degree, Congenital

Overview: Atrioventricular Block, Third Degree, Congenital
Differential Diagnoses & Workup: Atrioventricular Block, Third Degree, Congenital
Treatment & Medication: Atrioventricular Block, Third Degree, Congenital
Follow-up: Atrioventricular Block, Third Degree, Congenital
References
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References

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Further Reading

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Keywords

third degree congenital atrioventricular block, third-degree congenital atrioventricular block, CAVB, congenital heart block, congenital complete heart block, congenital complete atrioventricular block, atrioventricular, AV, congential complete AV block, congential complete A-V block, autoimmune complete heart block, 3° atrioventricular block, 3° AV block, 3° A-V block, collagen vascular disease, systemic lupus erythematosus, Sjogren syndrome, Hunter syndrome, Hurler syndrome, myocarditis, hydrops fetalis, endocardial fibroelastosis, L-transposition of the great arteries, ventricular septal defect

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Contributor Information and Disclosures

Author

Monesha Gupta, MD, MBBS, FAAP, FACC, Assistant Professor, Division of Pediatric Cardiology, University of Texas Medical School, Children's Memorial Hermann Hospital
Monesha Gupta, MD, MBBS, FAAP, FACC is a member of the following medical societies: American Academy of Pediatrics, American College of Cardiology, American Society of Echocardiography, Medical Council of India, and Society of Pediatric Echocardiography
Disclosure: Nothing to disclose.

Coauthor(s)

Robert Murray Hamilton, MD, MSc, FRCPC, Section Head, Electrophysiology, Director, High-Risk Hereditary Heart Conditions Clinic, Labatt Family Heart Centre; Professor, Department of Pediatrics, Associate Scientist, Physiology and Experimental Medicine, The Hospital for Sick Children and Research Institute, University of Toronto, Canada
Robert Murray Hamilton, MD, MSc, FRCPC is a member of the following medical societies: American Heart Association, Canadian Cardiovascular Society, Canadian Medical Association, Canadian Medical Protective Association, Cardiac Electrophysiology Society, Heart Rhythm Society, Ontario Medical Association, Pediatric Electrophysiology Society, Royal College of Physicians and Surgeons of Canada, and Society for Pediatric Research
Disclosure: Nothing to disclose.

Medical Editor

Charles I Berul, MD, Associate Professor of Pediatrics, Harvard Medical School; Senior Associate, Department of Cardiology, Children's Hospital of Boston
Charles I Berul, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Cardiology, American Heart Association, Heart Rhythm Society, and Society for Pediatric Research
Disclosure: Nothing to disclose.

Pharmacy Editor

Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine
Disclosure: Pfizer Inc Stock Investment from financial planner; Avanir Pharma Stock Investment from financial planner ; WebMD Salary and stock Employment and investment from financial planner

Managing Editor

Alvin J Chin, MD, Professor of Pediatrics, Division of Cardiology, The Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine
Alvin J Chin, MD is a member of the following medical societies: American Association for the Advancement of Science and American Heart Association
Disclosure: Nothing to disclose.

CME Editor

Gilbert Herzberg, MD, Assistant Professor, Department of Pediatrics, Section of Pediatric Cardiology, New York Medical College
Gilbert Herzberg, MD is a member of the following medical societies: American Academy of Pediatrics
Disclosure: Nothing to disclose.

Chief Editor

Steven R Neish, MD, SM, Director of Pediatric Cardiology Fellowship Program, Associate Professor, Department of Pediatrics, Baylor College of Medicine
Steven R Neish, MD, SM is a member of the following medical societies: American Academy of Pediatrics, American College of Cardiology, and American Heart Association
Disclosure: Nothing to disclose.

 
 
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