Cardiomyopathy

Cardiomyopathy
Classification and external resources
File:Idiopathic cardiomyopathy, gross pathology 20G0018 lores.jpg Opened left ventricle of heart shows a thickened, dilated left ventricle with subendocardial fibrosis manifested as increased whiteness of endocardium.
ICD-10	I42.0
ICD-9	425.4
DiseasesDB	2137
MedlinePlus	001105
MeSH	D009202

Cardiomyopathy, which literally means "heart muscle disease," is the deterioration of the function of the myocardium (i.e., the actual heart muscle) for any reason. People with cardiomyopathy are often at risk of arrhythmia or sudden cardiac death or both.

Cardiomyopathies can be categorized as extrinsic or intrinsic.

Extrinsic cardiomyopathies

These are cardiomyopathies where the primary pathology is outside the myocardium itself. Most cardiomyopathies are extrinsic, because by far the most common cause of a cardiomyopathy is ischemia. The World Health Organization calls these specific cardiomyopathies:

• Congenital heart disease
• Nutritional diseases
• Ischemic (or non-ischaemic) cardiomyopathy
• Hypertensive cardiomyopathy
• Valvular cardiomyopathy
• Inflammatory cardiomyopathy (including Chagas disease, which is an important cause of cardiomyopathy in Central and South America.)
• Cardiomyopathy secondary to a systemic metabolic disease
• Alcoholic cardiomyopathy
• Diabetic cardiomyopathy
• Restrictive cardiomyopathy

Ischemic cardiomyopathy

Commonly used term "ischemic cardiomyopathy," referring to myocardial ischemia and infarction, is not supported by current cardiomyopathies classification schemes.

Ischemic cardiomyopathy is a weakness in the muscle of the heart due to inadequate oxygen delivery to the myocardium with coronary artery disease being the most common cause. Anemia and sleep apnea are relatively common conditions that can contribute to ischemic myocardium and hyperthyroidism can cause a 'relative' ischemia secondary to high output heart failure. Individuals with ischemic cardiomyopathy typically have a history of myocardial infarction (heart attack), although longstanding ischemia can cause enough damage to the myocardium to precipitate a clinically significant cardiomyopathy even in the absence of myocardial infarction. In a typical presentation, the area of the heart affected by a myocardial infarction will initially become necrotic as it dies, and will then be replaced by myocardial scarring (fibrosis). This fibrotic tissue is akinetic; it is no longer muscle and cannot contribute to the heart's function as a pump. If the akinetic region of the heart is substantial enough, the affected side of the heart (i.e. the left or right side) will go into failure, and this failure is the functional result of an ischemic cardiomyopathy.

In some individuals, severe emotional stress may lead to "takotsubo cardiomyopathy", a specific cardiomyopathy which has a particular aetiology.

Cardiomyopathy due to systemic diseases

Many diseases can result in cardiomyopathy. These include diseases like hemochromatosis, (an abnormal accumulation of iron in the liver and other organs), amyloidosis (an abnormal accumulation of the amyloid protein), diabetes, hyperthyroidism, lysosomal storage diseases and the muscular dystrophies.

Some current chemotheraphy drugs can also be the cause. However, this is only likely in 2-3% of patients.

Intrinsic cardiomyopathies

See also: Myocarditis

An intrinsic cardiomyopathy is defined as weakness in the muscle of the heart that is not due to an identifiable external cause. This definition was used to categorize previously idiopathic cardiomyopathies although specific external causes have since been identified for many. For example, alcoholism has been identified as a cause for some forms of dilated cardiomyopathy.

To make a diagnosis of an intrinsic cardiomyopathy, significant coronary artery disease should be ruled out (amongst other things). The term intrinsic cardiomyopathy does not describe the specific etiology of weakened heart muscle. The intrinsic cardiomyopathies consist of a variety of disease states, each with their own causes.

Many intrinsic cardiomyopathies now have identifiable external causes including drug and alcohol toxicity, certain infections (including Hepatitis C), and various genetic and idiopathic (i.e., unknown) causes.

Intrinsic cardiomyopathies are generally classified into four types, but additional types are also recognized:

• Dilated cardiomyopathy (DCM), the most common form, and one of the leading indications for heart transplantation. In DCM the heart (especially the left ventricle) is enlarged and the pumping function is diminished. Approximately 40% of cases are familial, but the genetics are poorly understood compared with HCM. In some cases it manifests as peripartum cardiomyopathy, and in other cases it may be associated with alcoholism.
• Hypertrophic cardiomyopathy (HCM or HOCM), a genetic disorder caused by various mutations in genes encoding sarcomeric proteins. Approximately 45% of mutations occur in B-myosin heavy chain gene while 35% occur in cardiac myosin binding protein C gene. In HCM the heart muscle is thickened, which can obstruct blood flow and prevent the heart from functioning properly.
• Arrhythmogenic right ventricular cardiomyopathy (ARVC) arises from an electrical disturbance of the heart in which heart muscle is replaced by fibrous scar tissue. The right ventricle is generally most affected.
• Restrictive cardiomyopathy (RCM) is an uncommon cardiomyopathy. The walls of the ventricles are stiff, but may not be thickened, and resist the normal filling of the heart with blood. A rare form of restrictive cardiomyopathy is the obliterative cardiomyopathy, seen in the hypereosinophilic syndrome. In this type of cardiomyopathy, the myocardium in the apices of the left and right ventricles becomes thickened and fibrotic, causing a decrease in the volumes of the ventricles and a type of restrictive cardiomyopathy.
• Noncompaction cardiomyopathy has been recognized as a separate type since the 1980s. The term refers to a cardiomyopathy where the left ventricle wall has failed to grow properly from birth and has a spongy appearance when viewed during an echocardiogram.

Signs and symptoms

Symptoms and signs may mimic those of almost any form of heart disease. Chest pain is common. Mild myocarditis or cardiomyopathy is frequently asymptomatic; severe cases are associated with heart failure, arrhythmias, and systemic embolization. Manifestations of the underlying disease (e.g., Chagas' disease) may be prominent. Most patients with biopsy-proven myocarditis report a recent viral prodrome preceding cardiovascular symptoms.

ECG abnormalities are often present, although the changes are frequently nonspecific. A pattern characteristic of left ventricular hypertrophy may be present. Flat or inverted T waves are most common, often with low-voltage QRS complexes. Intraventricular conduction defects and bundle branch block, especially left bundle branch block, are also common. An echocardiogram is useful to detect wall motion abnormalities or a pericardial effusion. Chest radiographs can be normal or can show evidence of congestive heart failure with pulmonary edema or cardiomegaly.

Treatment

Treatment depends on the type of cardiomyopathy, but may include medication, implanted pacemakers, defibrillators, or ventricular assist devices (LVADs), or ablation. The goal of treatment is often symptom relief, and some patients may eventually require a heart transplant. Treatment of cardiomyopathy (and other heart diseases) using alternative methods such as stem cell therapy is commercially available but is not supported by convincing evidence.

Famous cases

In 1966, the addition of cobalt compounds to stabilize beer foam in Canada led to cardiomyopathy, which came to be known as beer drinker's cardiomyopathy.

Dave Williams of Drowning Pool died of cardiomyopathy in 2002.

Dr. Robert Atkins, inventor of "The Atkins Diet" suffered from cardiomyopathy in the years before his death from a fall.

Alexei Cherepanov, 19 year old professional ice hockey player, died of cardiomyopathy during an ice hockey game in 2008.

Andy Hallett, a 33 year old actor from the television series Angel, died of congestive heart failure in 2009, brought on by a cardiomyopathy from a tooth infection five years earlier.

Michael James Hegstrand aka Road Warrior Hawk an American professional wrestler.

Slash, guitarist for Guns N Roses, survived cardiomyopathy .

Reggie Lewis, captain and all-star of the Boston Celtics, died from hypertrophic cardiomyopathy at age 27.

Marc-Vivien Foé, Cameroonian international professional football (soccer) player, collapsed and died of hypertrophic obstructive cardiomyopathy (HOCM) aged 28 during a FIFA Confederations Cup Match on 26 June 2003.

Cuttino Mobley, a retired NBA player who last played for the LA Clippers, was forced to retire after being diagnosed with hypertrophic cardiomyopathy in late 2008.

Hank Gathers, a college basketball star recruit who played for Loyola Marymount University, collapsed during a free throw attempt against UCSB and later again against the University of Portland. The second time he never got up and was pronounced dead on arrival.

Nick Carter of the Backstreet Boys was diagnosed with cardiomyopathy after suffering chest pains.

Katie Gallagher, who placed second on the TV reality show Survivor: Palau, was diagnosed with viral cardiomyopathy several years later.

The Amazing Jonathan was diagnosed with "a serious heart condition" in March 2007. The performer's website identified the condition as cardiomyopathy and went on to assert that, due to a combination of weight loss and blood thinners, he was doing well and did not intend to retire.

Genetic Causes

Genetic causes of cardiomyopathy

Phenotype	Inheritance pattern	Chromosomal locus	Gene	Protein	Skeletal myopathy
Dilated cardiomyopathy	X-linked	Xp21	dystrophin	Dystrophin	Duchenne / Becker muscular dystrophy
	X-linked	Xq28	G4.5	Tafazzin	Barth syndrome
	Autosomal dominant	15q14	actin	Actin	Nemaline myopathy
		2q35	desmin	Desmin	Desmin myopathy
		5q33	δ-sarcoglycan	δ-sarcoglycan	Limb girdle muscular dystrophy 2F
		1q32	Troponin T	Troponin T
		14q11	β-myosin heavy chain	β-myosin heavy chain
		15q2	α-tropomyosin	α-tropomyosin	Nemaline myopathy
		Midna	Mitochondrial respiratory chain	Mitochondrial respiratory chain	Mitochondrial myopathy
Dilated cardiomyopathy with conduction disease	Autosomal dominant	1q21	lamin A/C	Lamin A/C	Emery-Dreifuss muscular dystrophy
Hypertrophic cardiomyopathy	Autosomal dominant	14q11	β-myosin heavy chain	β-myosin heavy chain
		14q11	β-myosin heavy chain	β-myosin heavey chain
		1q32	Troponin T	Troponin T
		12q23	Troponin T	Troponin T
		15q2	α-tropomyosin	α-tropomyosin	Nemaline myopathy
		11q11	myosin-binding protein C	myosin-binding protein C
		3p21	myosin essential light chain	myosin essential light chain
		3p21	myosin regulatory light chain	myosin regulatory light chain
		2p31	titin	Titin
Hypertrophic cardiomyopathy with Wolf-Parkinson-White syndrome		7q3	AMPK	AMPK
		MIDINA	Mitochondrial respiratory chain	Mitochondrial respiratory chain	Mitochondrial myopathy
Left ventricular noncompaction	X-linked	Xq28	G4.5	Tafazzin	Barth syndrome
	Autosomal dominant	18q12	α-dystrobrevin	α-Dystrobrevin	Muscular dystrophy

External links

• The Children's Cardiomyopathy Foundation, a non-profit that provides support to parents of affected children and accelerates research related to diagnosis, treatments and cures for all types of cardiomyopathies in children.
• The Cardiomyopathy Association A site is designed to provide you with information on the main forms of the heart muscle disease known as cardiomyopathy. Great information for adults and young.
• Cardiomyopathy information from Seattle Children's Hospital Heart Center
• Information from the Stanford Hypertrophic Cardiomyopathy Center
• Cardiomyopathy-related antibodies
• Treatment Cardiomyopathy (Alternative Medicine)
• Cardiac Risk in the Young
• Information on Cardiomyopathy from MedlinePlus
• Yahoo! Cardiomyopathy Group, A group site providing information and support to Cardiomyopathy patients by Cardiomyopathy patients.

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