or DCM (also known as ''congestive cardiomyopathy''), is a disease of the
Myocardium (the
Muscle of the
Heart ) in which a portion of the myocardium is dilated, often without any obvious cause. About one in three cases of
Congestive Heart Failure (CHF) is due to dilated cardiomyopathy.
1
A
Cardiomyopathy is any disease that primarily affects the muscle of the heart. In DCM, left and/or right ventricular
Systolic pump function of the heart is impaired, leading to progressive cardiac enlargement and
Hypertrophy , a process called ''remodeling''.
1
Dilated cardiomyopathy is the most common form of cardiomyopathy. It occurs more frequently in men than in women, and is most common between the ages of 20 and 60 years.
2
Although no cause is apparent in many cases, dilated cardiomyopathy is probably the end result of myocardial damage produced by a variety of toxic, metabolic, or infectious agents. It may be the late sequel of acute viral
Myocarditis , possibly mediated through an immunologic mechanism. Alcohol abuse is also strongly associted with the development of dilated cardiomyopthy in some cases. Autoimmune mechanisms are also suggested as a cause for dilated cardiomyopathy.
3
A reversible form of dilated cardiomyopahty may be found with alcohol abuse, pregnancy, thyroid disease, cocaine use, and chronic uncontrolled
Tachycardia .
About 20-40% of patients have familial forms of the disease, with
Mutation s of genes encoding
Cytoskeletal , contractile, or other proteins present in myocardial cells.
4 The disease is genetically heterogenous, but the most common form of its transmission is an
Autosomal Dominant pattern.
Autosomal Recessive ,
X-linked , and
Mitochondrial inheritance of the disease is also found.
5
Although the disease is more common in African-Americans than in whites, it may occur in any patient population.
Symptoms of left- and right-sided congestive heart failure develop gradually in most patients. Left ventricular dilatation may be present for months or even years before the patient becomes symptomatic.
Vague chest pain may be present, but typical
Angina Pectoris is unusual and suggests the presence of concomitant
Ischemic Heart Disease .
Syncope due to
Arrhythmias , and systemic
Embolism may occur.
The patients may present variable degrees of cardiac enlargement, and findings of
Congestive Heart Failure . In advance stages of the disease, the
Pulse Pressure is narrowed and the
Jugular Venous Pressure is elevated. Third and fourth heart sounds are common.
Mitral or
Tricuspid Regurgitation may occur, presented by systolic
Murmur s upon
Auscultation (see
Mitral Regurgitation and
Tricuspid Insufficiency for more details about the findings).
Generalized enlargement of the heart is seen upon normal
Chest X-ray .
Pleural Effusion may also be noticed, which is due to pulmonary venous hypertension.
The
Electrocardiogram often shows
Sinus Tachycardia or
Atrial Fibrillation ,
Ventricular Arrhythmia s, left atrial abnormality, and sometimes intraventricual conduction defects and low voltage.
Echocardiogram shows left ventricular dilatation with normal or thinned walls and reduced
Ejection Fraction . Cardiac
Catheterization and
Coronary Angiography are often performed to exclude ischemic heart disease.
The majority of patients, particularly those over 55 years of age, die within 3 years of the onset of the symptoms. Death is due to either
Congestive Heart Failure or ventricular
Tachy- or
Bradyarrhythmia s.
Patients are given the standard therapy for heart failure, including salt restriction,
Angiotensin-converting Enzyme (ACE) inhibitors,
Diuretic s, and
Digitalis .
Anticoagulants may also be used. Alcohol should be avoided.
Artificial Pacemaker s may be used in patients with intraventricular conduction delay, and
Implantable Cardioverter-defibrillator s in those at risk of arrhythmia. These forms of treatment have been shown to improve symptoms and reduce hospitalization.
In patients with advanced disease who are refractory to medical therapy, cardiac
Transplantation should be considered.
1. Harrison's Principles of Internal Medicine, 16th edition. Kasper, Braunwald, Fauci, Hauser, Longo, Jameson. ISBN 0-07-139140-1
2. Robbins Basic Pathology, 7th edition. Kumar, Cotran, Robbins. ISBN 0-7216-9274-5
3. San Martin MA, Garcia A, Rodriguez FJ, Terol I. Dilated cardiomyopathy and autoimmunity: an overview of current knowledge and perspectives. Rev Esp Cardiol. 2002 May;55(5):514-24. PMID 12015932
4. Ross J Jr. Dilated cardiomyopathy: concepts derived from gene deficient and transgenic animal models. Circ J. 2002 Mar;66(3):219-24. PMID 11922267
5. Schonberger J, Seidman CE. Many roads lead to a broken heart: the genetics of dilated cardiomyopathy. Am J Hum Genet. 2001 Aug;69(2):249-60. Epub 2001 Jul 6. PMID 11443548
