Heart Muscle Disease

Hypertrophic Cardiomyopathy

• Relatively common.
• Affects 1:500 in the general population.
• Is the commonest cause of sudden cardiac death in the young in the USA.
• Autosomal dominant genetic heart disease.
• It is characterized by hypertrophied non-dilating LV in the absence of cardiac diseases capable of producing that magnitude of wall thickness.
• Caused by mutations affecting β-myosin heavy chain gene and myosinbinding protein C.
• Clinically, the patient has a history of fainting attacks on activity, a jerky pulse, asymmetrical septal hypertrophy (ASH), and systolic anterior mitral motion (SAM).
• Offspring of affected individuals need screening.
• Treatment options include:
• Alcohol infusion
• Surgery
• β-blockers are the main therapy.

Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)

• An uncommon inherited heart disease.
• Prevalence 1:5000.
• Premature loss of cardiac cells in the right ventricle by increased apoptosis.
• Affects young individuals.
• A cause of Sudden Unexpected Death (SUD) in the young.
• High-grade ventricular arrhythmia.
• Treatment options include:
• β-blockers
• Implantable cardioverter defibrillator (ICD)

Left Ventricular Non-Compaction

• Recently recognized cardiomyopathy characterized by sponginess in the morphological appearance of the LV. Non-compaction involves the apical portion of the LV with deep intertrabecular recesses communicating with the cavity of the LV.
• Diagnosis made from 2-dimensional echocardiograph.
• Complications include heart failure, thromboembolism, arrhythmias, and Sudden Unexpected Death (SUD).

Conduction Defects

• Lenegre disease: progressive cardiac conduction defect in the His-Purkinje system leading to widening of the QRS complexes.
• Sick sinus syndrome: brady-tachy syndrome.

Ion Channelopathies

• Only recognized in the 2006 classification.
• Long QT syndromes:
• Romano-Ward - autosomal dominant.
• Jervell and Lange-Nielsen - autosomal recessive associated with deafness.
• Brugada - described in 1992, distinctive ECG feature- RBBB with ST elevation in V1-V3.
• Prolonged QTc is associated with a high risk of torsades de pointes, which is a risk for Sudden Unexpected Death (SUD).

Dilated Cardiomyopathy

• Is a common cardiomyopathy.
• Virtually all heart diseases end up as DCM.
• Patient has dilated heart chambers with progressive systolic heart failure.
• 20-35% have been reported to be familial.
• Common causes include viral myocarditis, HIV, Chagas disease, and drugs e.g., doxorubicin.
• Treatment is as in the treatment of heart failure.
• Complications include arrhythmias and thromboembolism.

Restrictive Cardiomyopathy

• Acute form seen in temperate environments.
• Chronic form seen in the tropics: EMF (Endomyocardial Fibrosis).
• Fibrosis of the endocardium with impairment of ventricular relaxation.
• EMF is a cause of "egg on stick" appearance.

Myocarditis

• Called inflammatory cardiomyopathy.
• Can be acute or chronic inflammatory process affecting the heart. E.g., coxsackievirus, adenovirus, parvovirus, HIV, rocky mountain spotted fever.
• More often than not, it produces DCM (Dilated Cardiomyopathy).
• Diagnosis is confirmed through myocardial biopsy.

Tako-Tsubo (Broken Heart Syndrome)

• First reported in 1990 in Japan.
• Stress-induced cardiomyopathy.
• Characterized by acute but rapidly reversible left ventricular systolic dysfunction triggered by profound psychological stress.
• Acute apical ballooning.
• Affects older women aged 50-75 years.
• Recovery within a month.
• Stressors include unexpected loss, domestic violence, injury to a close person, illness, financial loss, fierce argument, intense fear, surprise party, public speaking, etc. (Am Heart J (2008), 155 (3): 408-417).

Peripartum Cardiomyopathy

• Heart failure associated with pregnancy usually in the 3rd trimester or up to 6 months after delivery.
• Cultural factors play a major role in its pathophysiology.
• Common among Hausa women in the Zaria Area.
• Women who have recently delivered are bathed with very hot water and sleep in heated rooms with consumption of pap to which a lot of potash has been added.
• About 50% have complete recovery within 6 months but may progress.