Cardiomyopathies: Types and Characteristics

Cardiomyopathies

• These affect the mechanical and electrical functions of the myocardium.
• They are usually associated with ventricular hypertrophy or dilation.
• Cardiomyopathies can be confined to the heart or part of systemic disorders.
• They can lead to cardiovascular death or progressive heart failure.

Primary Cardiomyopathies

• Classified as genetic, mixed, or acquired, based on etiology.

Genetic Cardiomyopathies

• Include hypertrophic cardiomyopathy (HCM), arrhythmogenic right ventricular cardiomyopathy (ARVC), left ventricular noncompaction cardiomyopathy, inherited conduction system disorders, and ion channelopathies.

Acquired Cardiomyopathies

• Those that originate in the inflammatory process such as myocarditis.
• Stress also known as "tako-tsubo" pericarditis.
• Pregnancy also known as peripartum cardiomyopathy.

Hypertrophic Cardiomyopathy (HCM)

• Characterized by unexplained left ventricular hypertrophy and disproportionate thickening of the interventricular septum.
• Can cause abnormal diastolic filling, cardiac arrhythmias, and intermittent left ventricular outflow obstruction.
• Implantable cardioverter defibrillators (ICDs) can be lifesaving.
• Clinical manifestations may include dyspnea, chest pain during exertion, exercise intolerance, syncope, and arrhythmias.

Arrhythmogenic Right Ventricular Cardiomyopathy/ Dysplasia (ARVC)

• The second most common cause of sudden cardiac death in young people after HCM.
• Accounts for up to 10% of sudden cardiac deaths in patients < 65 years.
• Causes ventricular ectopic beats or sustained VT, typically with palpitations, syncope, or cardiac arrest precipitated by exercise.
• The first presenting symptom may be sudden cardiac death.
• Over time, patients may develop right ventricular failure, progressing to biventricular failure and dilated cardiomyopathy.
• Often has a family history of sudden cardiac death.
• Epsilon waves are highly specific in ARVC; myocytes replaced by fat cause delayed excitation during the ST segment on ECG.

Left Ventricular Noncompaction

• Characterized by a distinct "spongy" morphological appearance of the myocardium
• Signs and symptoms are related to arrhythmias, embolic events, and heart failure.
• Treatment focuses on preventing symptoms of heart failure, arrhythmias, systemic embolic events, and sudden cardiac death.

Ion Channelopathies

• In the heart, includes long QT syndrome (LQTS), short QT syndrome (SQTS), Brugada syndrome, and catecholaminergic polymorphic ventricular tachycardia.

Brugada Syndrome

• Diagnosis requires typical ECG abnormalities plus one clinical characteristic.
• Clinical characteristics include a history of VT/VF or sudden cardiac death, a family history of coved-type ECG, agonal respiration during sleep, or inducible VT/VF during EP study.

Mixed (Genetic and Nongenetic) Cardiomyopathies

• Also known as Dilated Cardiomyopathy (DCM).
• DCM is a common cause of heart failure for heart transplantation.
• DCM is characterized by ventricular enlargement, reduced ventricular wall thickness, and impaired systolic function.
• Manifestations include dyspnea, orthopnea, and reduced exercise capacity.
• End stages have ejection fractions less than 25% whereas normal is approximately 50% to 60%.
• Blood stasis in the heart chambers can lead to thrombus formation and systemic emboli.

Acquired Cardiomyopathies, Myocarditis

• Also known as Inflammatory Cardiomyopathy
• Myocarditis involves inflammation of the myocardium.
• Clinical symptoms can vary from fever and myalgias to hemodynamic collapse and sudden death.
• Acute viral myocarditis progresses through acute viral infection, autoimmune activation, and myocardial injury, potentially resulting in DCM.

Myocarditis Signs and Symptoms

• The clinical presentation can vary from asymptomatic to cardiogenic shock and sudden cardiac death
• Symptoms include fever, malaise, fatigue, altered LOC
• Chest pain can be diffuse or severe and central
• Other symptoms: hypotension, palpitations, ventricular arrhythmias, dyspnea, orthopnea, pulmonary rales, peripheral edema, presyncope, and syncope.

Myocarditis ECG Changes

• Common ECG abnormalities including sinus tachycardia and non-specific ST segment and T wave changes.
• Other variable ECG changes can include prolonged QRS, QT prolongation, diffuse T wave inversion, ventricular arrhythmias, and AV conduction defects.
• The inflammation to the adjacent pericardium = myopericarditis and will also display ECG features or pericarditis

Peripartum Cardiomyopathy

• This is a rare disorder that occurs during the last trimester of pregnancy or the first 5-6 months after delivery
• Incidence is greater in African American, multiparous, or older women, and in women with twin fetuses, preeclampsia, or use of tocolytic therapy.
• Presents just as LV systolic dysfunction includes shortness of breath, palpitations, edema, and orthopnea.
• The criteria for the definition include:

1. heart failure during the last month of pregnancy or within 5 months after delivery
2. No identifiable cause
3. No identifiable cause before the last month of pregnancy
4. Evidence of systolic dysfunction.

Stress or "Tako-Tsubo" Cardiomyopathy

• Pathophysiology is a combination of sympathetic nervous system activation, microvascular spasm, and underlying LVOT obstruction.
• Clinical significance shows 90% of cases worldwide occur in post-menopausal women, typically associated with sudden stress.
• Cases in men related to physical stress
• Treatment consists of being largely supportive plus LV function spontaneously return after 21 days
• Anticoagulants initiated for patients with large areas of cardiac, as they are at high risk of cerebrovascular thromboembolic can occur

Secondary Cardiomyopathies

• A heart muscle disease in the presence of the multisystem disorder
• Includes drugs, diabetes mellitus, muscular dystrophy, autoimmune disorders, cancer treatment agents, and cancer drugs.
• Alcoholic cardiomyopathy is the single most identifiable cause of DCM in the Western world.

Endocarditis

• Inflammation of inner lining of hearts chambers due to infections

Endocarditis Pathophysiology

1. Bacteremia- microorganisms present in the blood
2. Adhesion- stick to damaged endothelium
3. Colonization- proliferation of organisms with inflammation leads to mature vegetation

• Growths on the valves produce toxins that cause holes in the valves and spreading, the vegetative emboli, outside the heart and blood vessels.
• Diagnosis consists of reviewing patient history, patient presentation, signs and symptoms, blood cultures, echo/chest x-ray and CT
• Signs and Symptoms include chest pain, dyspnea, cough, fatigue, night sweats, chills, edema, and a heart murmur.
• Vitals include fever, hypotension, tachycardia, tachypnea, and arrhythmias.
• Treatments includes administering oxygen, fluids, 12 lead, then transport to hospital
• Treatment in hospital includes use of antibiotics/surgery. Risk with iv drugs

Pearls of Wisdom

• Consider endocarditis in patients with a history of IV drug use.
• Prepare for complications such as sepsis, PE, MI, stroke, abscesses.
• Manifestations can occur for several months.
• look for key signs for patient.