Cardiomyopathies

Learning objectives

Cardiomyopathy is myocardial disorder in which the heart muscle is structurally and functionally abnormal
Can be inherited or acquired
Can affect all age groups
Affects the shape, function, and electrical system of the heart.
Signs and symptoms can usually be managed successfully and patients can have a good life expectancy

Dilatation of the left and right ventricles, impaired systolic function
Major cause of heart failure and arrhythmia in young adults
Two-thirds of cases are idiopathic
Possible causes:
- Familial association
- Post-viral infection
- Part of a disease process (ischemic heart disease, hypertension, diabetes, malformation syndrome, alcohol excess, neuromuscular disorder, inborn errors of metabolism, exposure to cardiotoxic agents)
Asymptomatic in early stages
Symptoms of heart failure (dyspnea, fatigue, ascites, peripheral edema, arrhythmias)
Embolic events and sudden death may occur at a later stage
Diagnosis: Echocardiography, chest radiograph, electrocardiography, blood tests, detailed medical and family history, physical examination

SVR, systemic vascular resistance; BIS, bispectral index; ICU, intensive care unit

Hypertrophy of the left ventricle in the absence of other structural or functional abnormalities
Inherited disease of the myocardium
Hypertrophy can be asymmetrical, concentric, midventricular, apical, and can also involve the right ventricle
Diastolic impairment of the left ventricle
End-stage: Biventricular systolic dysfunction due to myocardial fibrosis
70% of cases have obstructive hypertrophy
Majority of patients is asymptomatic
Symptoms of angina and heart failure (dyspnea, chest pain, syncope, arrhythmia)
Severe complications: Angina pectoris, heart failure, sudden death

SVR, systemic vascular resistance; LVOTO, left ventricular outflow tract obstruction

Impairment of ventricular diastolic function due to fibrotic or infiltrative changes in the myocardium and/or subendocardium
Primary or secondary (amyloidosis, sarcoidosis, hemochromatosis, ischemic heart disease, hypertension, valvular disease)
Symptoms of biventricular failure (dyspnoea, orthopnea, fatigue, palpitation, edema, chest pain)
On physical examination, patients may have an audible third heart sound, systolic murmur, raised jugular venous pressure, ascites, and peripheral edema
Diagnosis: Echocardiography, endomyocardial biopsy, computed tomography, cardiac MRI

General anesthesia causes vasodilation, suppresses the myocardium, and reduces venous return. The latter can be exacerbated by intermittent positive ventilation resulting in cardiac arrest.
Invasive arterial blood pressure monitoring and transesophageal echocardiography are useful in identifying the causes of cardiovascular instability.
Hemodynamic goals:
- Maintain adequate preload, SVR, and sinus rhythm
- Use an anesthetic agent with minimal cardiovascular effect (ketamine or etomidate)

Structural abnormalities and cardiac dysfunction of the right ventricle, can also involve left ventricle
Complex genetic condition
Other causes: Degenerative disease, infection, inflammation
Usually starts as a localized disease with regional wall abnormalities
Development of right bundle branch block followed by right ventricular failure between the fourth and fifth decades of life
Young patients often present with arrhythmia, syncope, cardiac arrest, or sudden death
3 clinical phases:
- Phase 1 (concealed disease): Some structural abnormality in the myocardium, patients can present with sudden cardiac death
- Phase 2 (overt disease): Established structural abnormality of the myocardium, patients present with arrhythmias and syncope
- Phase 3 (End-stage disease): Severe structural changes