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$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.