What Is Cardiomyopathy?
The word cardiomyopathy means heart muscle disease. In medicine, it is the collection of diseases of heart muscle (myocardium) in which the abnormal myocardium is associated with mechanical and/or electrical dysfunction, usually with ventricular hypertrophy It is currently classified according to dysfunction:
- Dilated cardiomyopathy: Dilation and contraction impairment in one or both ventricles.
- Hypertrophic cardiomyopathy: Enlarged right ventricle (occasionally the left), usually from a genetic cause.
- Restrictive cardiomyopathy: Non-dilated ventricles that still have abnormal ventricular filling.
- Arrhythmogenic right ventricular cardiomyopathy/dysplasia: A genetic disease of the right ventricle that causes arrhythmias.
- Cirrhotic cardiomyopathy: Associated with alcoholism.
- Cardiomyopathy-unclassified: Include left ventricular noncompaction (congenital tissue structure abnormality); and stress-induced cardiomyopathy (e.g., “broken heart syndrome”).
There are cardiomyopathies due to specific cardiac disorders, such as hypertension or aortic stenosis. There are also normal variations, such as “athlete’s heart,” which is structural change from intense training.
Cardiac Dysfunction from Cardiomyopathy
Systolic dysfunction: When systole, the contractile portion of the heart rhythm which propels blood from the heart, is weakened in cardiomyopathy, there is a reduction in cardiac output (specifically, the left ventricular ejection fraction, one of the measurable parameters in determining the severity of the dysfunction). This reduction in systolic function evokes compensation with left ventricular enlargement in attempt to create a larger pump; and a more sensitive response to stretch, which is part of the normal reflex dynamics of the heart.
Diastolic dysfunction: In cardiomyopathy that affects diastole, the relaxation (refilling) portion of the heart rhythm, there is abnormal filling and an elevated filling pressure. Diastolic dysfunction occurs with or without systolic dysfunction.
Signs and Symptoms:
- Clinical presentations of cardiomyopathy include
- dyspnea on exertion
- nocturnal dyspnea and orthopnea (dyspnea when lying flat)
- elevated jugular venous pressure
- abnormal lung sounds (rales)
- edema in the legs
Complications of Cardiomyopathy
The heart is a singular organ and the quintessential vital organ: dysfunction of it has morbidity and mortality implications. Heart failure can cause prolonged, debilitating illness when symptomatic and can result in death after crossing a crucial threshold of dysfunction. Heart failure, when asymptomatic, can result in sudden cardiac death.
How Is Cardiomyopathy Diagnosed?
Cardiomyopathy is heart failure, the failure of the heart as an efficient pump due to structural abnormalities that create functional abnormalities. The structural abnormalities involve enlargement of the left or both ventricles which affects systolic pumping and diastolic filling sequences. In patients who present clinically with signs of heart failure, the structural changes can be diagnosed with echocardiography (B mode ultrasound) and the functional changes with Doppler (flow) echocardiography.
Two types of heart failure are:
- Heart failure with preserved ejection fraction
- Heart failure with reduced ejection fraction
Clinical Presentations Suspicious for a Diagnosis
The clinical presentations (signs and symptoms of heart failure) for both of these are similar and warrant investigation:
- Dyspnea (dyspnea on exertion, paroxysmal nocturnal dyspnea, orthopnea)
- Higher than normal pressure in the jugular veins of the neck
- Pulmonary rales heard on auscultation of the chest
- Edema in the dependent portions of the body (legs)
Atrial fibrillation, associated with right-sided (preserved ejection fraction) heart failure, will subsequently reduce left ventricular filling and cardiac output. This results in hypotension and pulmonary congestion (pulmonary edema). Increased stress on the left ventricular wall, from hypertension, can delay relaxation of the myocardium.
Diastolic dysfunction raises the pulmonary venous pressure due to increased left atrial pressure. This can present clinically with wheezing and shortness of breath.
The degree of hemodynamic compromise can be severe enough to become life-threatening.
The approach to diagnosis includes ruling out other causes of heart failure: valvular heart disease, pulmonary hypertension, ventricular infarction, pericarditis, cardiac tamponade, amyloidosis, metastatic cancer, and drug toxicity.
- Chest X-ray: demonstrates cardiac enlargement or pulmonary edema (fluid back-up from dysfunctional systole and/or diastole).
- Electrocardiogram: ECG findings are usually nonspecific, but if there has been a prior infarction or current ischemia, this can be detected.
- Echocardiography: identifies let ventricular hypertrophy, left atrial enlargement, and elevations in pulmonary artery systolic pressure. A cardiac echogram is especially useful in proving that the ejection fraction is preserved, and the left ventricle remains normal. Alternately, it can determine left ventricular hypertrophy, left atrial enlargement, and reduced ejection fraction; alternately, it can steer the diagnosis away from cardiomyopathy by documenting valve disease.
The Doppler component can examine the flow dynamics that can determine diastolic filling pressures and left atrial volume. The remodeling of the left ventricle and diastolic dysfunction, when identified, portend morbidity and possible mortality.
- Blood tests: plasma natriuretic peptide levels are elevated in heart failure.
- Exercise testing: this can help separate heart failure from lung disease.
- Cardiac catheterization: generally used only when other diagnostic tests are inconclusive.
How Can Cardiomyopathy Be Managed?
Cardiomyopathy as heart failure requires treatment that attempts to restore function or compensate for dysfunction. The two distinct types of heart failure are:
- Heart failure with preserved ejection fraction
- Heart failure with reduced ejection fraction
Heart Failure with Preserved Ejection Fraction
These patients have symptoms and signs of heart failure but with a >50% left ventricular ejection (pump efficiency). Actual pharmacological or invasive management have not produced any promising therapies, so management is limited to addressing the associated signs and symptoms:
- Hypertension management via diet: Exercise, weight management, and treating lipid elevations with statins; antihypertensive medication
- Edema management via diuretics: To reduce volume overload that results in edema as well as ambulation, limb elevation, and compression stockings
- Atrial fibrillation treatment: To restore sinus rhythm if possible if not beta blockers and calcium channel blockers to control the rate
- Anticoagulation: To prevent thrombotic emboli and reduce the risk of stroke and cardiac or peripheral ischemia/infarction
- Cardiac rehabilitation: that uses exercise training to improve exercise potential
- Implantable pulmonary artery pressure monitor
Heart Failure with Reduced Ejection Fraction
Goals of management of heart failure with reduced ejection fraction are reduction of symptoms, increased function, lowering the rate of hospitalizations, and reducing the morbidity and mortality risks.
- Manage contributing factors such as hypertension (beta blockers, ACE inhibitors, angiotensin II receptor blockers or inhibitors, and diuretics); renovascular disease (antihypertensive medication, revascularization); ischemic heart disease (angina relief, smoking cessation, lipid management, and for repeat episodes, myocardial revascularization); valvular disease (surgical correction); bradycardia (pacemaker); antithrombotic therapy; obstructive sleep apnea (PEEP mask)
- Symptom control with beta blockers, ACE inhibitors, vasodilators (hydralazine), and aldosterone antagonists
- Implantables, such as implantable cardioverter-defibrillator, cardiac resynchronization via biventricular pacemaker, or both
- Cardiac rehabilitation that uses exercise training to improve exercise potential
- A protocol of repeat evaluations and when indicated, repeat echocardiogram
- Prolonged hospitalization for refractory cases
How Can I Prevent Cardiomyopathy from Happening?
Management of cardiomyopathy is tantamount to preventing aspects of it which can result in sudden cardiac death. All of the preventative measures for associated factors and unrelated comorbidities should be implemented to avoid mortality:
- Control of hypertension with antihypertensive medication
- Strict glycemic control and maintenance of target glycated hemoglobin A1c <7% for diabetics
- Weight management via diet/nutritional consultation, caloric restriction strategies, and lifestyle changes
- Smoking cessation and alcohol limitations
- Correction of dyslipidemia (elevated LDL-cholesterol, lower-than-normal HDL-cholesterol, elevated triglycerides) with statin drugs and follow-up for efficacy with serial blood work
- Diuretics for edema and to reduce volume overload which may contribute to pulmonary congestion/edema
- Cardioversion for atrial fibrillation
- Anticoagulation therapy for the prevention of thrombotic emboli that increase the risk of cardiac and peripheral (e.g., mesenteric) ischemia, infarction, and cerebrovascular accidents (stroke)
Direct involvement in recognizing the functional distortion of heart failure itself will impact morbidity and mortality, preventing disease progression that can negatively impact both:
- Early recognition and treatment of predisposing conditions (ischemic cardiac disease, hypertension, obesity and metabolic syndrome, unhealthy lifestyles, and sedentary habits)
- Early detection of left ventricular dysfunction (<40% ejection fraction) via echocardiography
- Treating both preserved ejection heart failure and reduced ejection heart failure will contribute to overall reduction in morbidity and mortality (antihypertensives, diuretics, vasodilators, sodium and fluid restriction, and anticoagulation prophylaxis)
- Treatment of left ventricular systolic dysfunction to prevent low output and decreased peripheral perfusion of end-organs (inotropic agents) and mechanical cardiac support (for those with severe disease–<25% ejection fraction: intra aortic balloon pump counter propulsion and extracorporeal membrane oxygenation devices)
Prevention of heart failure and heart failure-related complications runs the gamut from primary care to the use of specialists to implement aggressive strategies as the risks for morbidity and mortality rise.