$Unique_ID{BRK03803} $Pretitle{} $Title{Heart Block, Congenital} $Subject{Heart Block, Congenital Atrioventricular Block (AV) Block Congenital Heart Block (First, Second, and Third Degree) Congenital Heart Block Type I Congenital Heart Block Type II Mobitz Block, Types I and II Bundle Branch Block Lupus} $Subject{} $Volume{} $Log{} Copyright (C) 1988, 1989 National Organization for Rare Disorders, Inc. 530: Heart Block, Congenital ** IMPORTANT ** It is possible the main Title of the article (Congenital Heart Block) is not the name you expected. Please check the SYNONYMS listing to find the alternate name. SYNONYMS Atrioventricular Block (AV) Block DISORDER SUBDIVISIONS Congenital Heart Block (First, Second, and Third Degree) Congenital Heart Block Type I Congenital Heart Block Type II Information on the following diseases can be found in the Related Disorders section of this report: Mobitz Block, Types I and II Bundle Branch Block Lupus General Discussion ** REMINDER ** The information contained in the Rare Disease Database is provided for educational purposes only. It should not be used for diagnostic or treatment purposes. If you wish to obtain more information about this disorder, please contact your personal physician and/or the agencies listed in the "Resources" section of this report. Congenital Heart Block is a rare birth defect in which the heart of a fetus does not develop properly. Symptoms Major symptoms in Type I Atrioventricular (Congenital Heart) Block include independent beating of the chambers (atria and ventricles) of the heart which can be detected through an Electrocardiogram (ECG) test. First Degree AV (Atrioventricular) Block is characterized by the slowed conduction of electrical impulses within the atrioventricular node of the heart. It does not produce outwardly apparent symptoms and is only detectable with the ECG test. Second Degree AV Block may produce other more serious symptoms. Third Degree AV Block (complete heart block) is characterized by failure of all atrial impulses to be conducted to the ventricles. Type II AV Block is characterized by organic heart disease and is more likely to be progressive, resulting in complete heart block. Causes Congenital Heart Block is an electrical disorder of the heart. The exact cause is not known. In some cases it may be caused by an infection in the uterus during pregnancy or an autoimmune disorder where the mother's antibodies are capable of crossing the placenta. The types of autoimmune disorders that are often associated with this birth defect are connective tissue disease, such as Lupus Erythematosus. Autoimmune Disorders are caused when the body's natural defenses against invading organisms (antibodies), for unknown reasons, begins to attack healthy tissue. Some cases may be linked to abnormal reactions by blood cells (serum antibodies), to a thyroid protein (thyroglobulin), organ wall (parietal) cells, or adrenal cells. Affected Population Congenital Heart Block is present at birth. The disorder affects males and females equally. Related Disorders Symptoms of the following disorders can be similar to those of Congenital Heart Block. Comparisons may be useful for a differential diagnosis. Mobitz Type I and II. Mobitz Type I, or Wenckebach AV block is characterized by progressive slowing of AV conduction of successive atrial impulses. It is usually a transient condition. Mobitz Type II AV block occurs suddenly and is nearly always a manifestation of organic heart disease. Type II nearly always requires a pacemaker to reestablish normal heart rhythms. Bundle Branch Block is a heart block caused by a lesion in one of the bundle branches in either the left or right sides of the heart. It usually indicates cardiovascular disease. Right Bundle Branch Block may be recorded in persons showing no clinical evidence of cardiovascular disease. In either case it is characterized by a slowing of the conduction in the bundle branches of the heart. Symptoms of the following disorders can be similar to those of Congenital Heart Block but they occur later in life as a result of disease or some other condition: acquired heart block secondary to cardiac surgery, rheumatic heart disease, or infectious disorders. The following disorders may precede the development of Congenital Heart Block in a fetus. They can be useful in identifying an underlying cause of some forms of this disorder: An intrauterine infection during pregnancy may cause Congenital Heart Block in a newborn. Systemic Lupus Erythematosus is an inflammatory connective tissue disease that can affect many parts of the body including the joints, skin and internal organs. Lupus is a disease of the body's immune system, most often striking young women between the ages of 15 and 35 years. The presence of Lupus in a pregnant woman should alert pediatricians to the possibility of Congenital Heart Block in an infant. (For more information on this disorder, choose "Lupus" as your search term in the Rare Disease Database.) Therapies: Standard Treatment of Congenital Heart Block Type I can consist of the administration of atropine, a drug which increases the AV conduction in the heart. In Heart Block Type II implantation of a pacemaker is often the treatment of choice. Therapies: Investigational The drug dexamethasone is being used as an experimental treatment for mothers affected with lupus erythematosus when they are pregnant. Plasmapheresis (3 times a week) is also being investigated as a possible treatment. It is hoped that plasmapheresis may diminish the amount of antibodies that are able to cross the placenta to the affected infant. This procedure is being tried on an experimental basis when conservative measure have proven ineffective. Plasmapheresis may be of benefit in some cases when the pregnant mother is afflicted with connective tissue disease, especially lupus. This procedure is a method for removing unwanted substances (toxins, metabolic substances and plasma parts) from the blood. Blood is removed from the patient and blood cells are separated from plasma. The patient's plasma is then replaced with other human plasma and the blood is retransfused into the patient. This type of therapy is still under investigation and cannot be considered a standard treatment. More research is needed before plasmapheresis can be recommended for use in all but the most high risk cases of Prenatal Congenital Heart Block due to maternal connective tissue disease. This disease entry is based upon medical information available through November 1988. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder. Resources For more information on Congenital heart block, please contact: National Organization for Rare Disorders (NORD) P.O. Box 8923 New Fairfield, CT 06812-1783 (203) 746-6518 American Heart Association National Center 7320 Greenville Ave. Dallas, TX 75231 (214) 750-5300 NIH/National Heart, Lung and Blood Institute (NHLBI) 9000 Rockville Pike Bethesda, MD 20892 (301) 496-4236 International Bundle Branch Block Association 6631 West 83 Street Los Angeles, CA 90045-2899 (213) 670-9132 Coaltion of Heritable Disorders of Connective Tissue c/o National Marfan Foundation 382 Main St. Port Washington, NY 11050 (516) 944-5412 For genetic information and genetic counseling referrals: March of Dimes Birth Defects Foundation 1275 Mamaroneck Avenue White Plains, NY 10605 (914) 428-7100 Alliance of Genetic Support Groups 35 Wisconsin Circle, Suite 440 Chevy Chase, MD 20815 (800) 336-GENE (301) 652-5553 References This Rare Disease Database entry is based upon outlines prepared by medical and dental students (1984-1986) at the Medical College of Virginia for their course in human genetics, and the following articles: INTERNAL MEDICINE, 2nd Ed.: Jay H. Stein, ed.-in-chief; Little, Brown and Co., 1987. Pp.301-570. DELAYED MATERNAL LUPUS AFTER DELIVERY OF OFFSPRING WITH CONGENITAL HEART BLOCK: B. S. Kasinath, et al.; Arch Intern Med (December 1982, issue 142 (13)). Pp. 2317. CONNECTIVE-TISSUE DISEASE, ANTIBODIES TO RIBONUCLEOPROTEIN, AND CONGENITAL HEART BLOCK; J.S. Scott, et al.; (N Engl J Med (July 28, 1983, issue 28 (309)). Pp. 209-212. MATERNAL ANTIBODIES AGAINST FETAL CARDIAC ANTIGENS IN CONGENITAL COMPLETE HEART BLOCK; P. V. Taylor, et al.; N Engl J Med (September 11, 1986, issue 315 (11)). Pp. 667-672.