CARDIOMYOPATHIES

The cardiomyopathies are a group of diseases that primarily affect myocardial muscle structure and function in the absence of a secondary cause such as coronary artery disease, hypertension, or valvular dysfunction.

 

"Cardiomyopathies are a heterogeneous group of diseases of the myocardium associated with mechanical and/or electrical dysfunction that usually (but not invariably) exhibit inappropriate ventricular hypertrophy or dilatation and are due to a variety of causes that frequently are genetic. Cardiomyopathies either are confined to the heart or are part of generalized systemic disorders, which may lead to cardiovascular death or progressive heart failure-related disability."

(American Heart Association in 2006)

Classification

According to the structural and functional abnormalities of the heart muscle
Dilated cardiomyopathy	Dilated left or both ventricle(s), with impaired contraction Ischemic, idiopathic, familial-genetic, immune, alcoholic, toxic, valvular
Hypertrophic cardiomyopathy	Left or right ventricular hypertrophy, or both Familial, with autosomal dominant inheritance
Restrictive cardiomyopathy	Restrictive filling and reduced diastolic filling of one or both ventricles; normal or near-normal systolic function Idiopathic, amyloidosis, endomyocardial fibrosis
Other Types -
Arrhythmogenic right ventricular cardiomyopathy (ARVC)	Fibrofatty replacement of right ventricular myocardium, Uhl's anomaly (parchment heart) Unknown; familial, usually autosomal dominant inheritance, with incomplete penetrance; possible autosomal recessive inheritance; rare forms associated with typical phenotype (eg, Naxos disease)
Unclassified cardiomyopathy	Not typical for previous four groups Fibroelastosis, noncompacted myocardium, systolic dysfunction with minimal dilation, mitochondrial disease

 

Pathophysiology

 

Dilated cardiomyopathy (DCM)

Dilated cardiomyopathy or DCM is a condition in which the heart becomes weakened and enlarged and cannot pump blood efficiently due to significant dilation of the ventricles without simultaneous hypertrophy and exhibit systolic dysfunction.

INCIDENCE

• DCM is the most common form of cardiomyopathy
• 5 to 8 cases per 100,000 people per year
• 3x more frequently in men than in women
• most common between the ages of 20-60 years
• 1in 3 cases of congestive heart failure (CHF) is due to dilated cardiomyopathy

ETIOLOGY

• Causative factor unknown - called idiopathic DCM (25% of all HF cases)
• Some conditions and diseases may cause DCM including
  • Pregnancy - Peripartum cardiomyopathy generally occurs in the last month of pregnancy or early after delivery
  • Heavy alcohol intake - Alcoholic cardiomyopathy usually results from heavy alcohol consumption over years
  • Viral infection (eg, influenza, Coxsacki virus, cytomegalo virus, HIV),
  • Chemotherapeutic medications – anthracyclin antitumour group (eg, daunorubicin, doxorubicin)
  • Chagas disease – topical protozon "Typonosoma Cruzi" disease found in South and central America
• Genetic-Familial cardiomyopathy is seen in 20% to 40% of patients with DCM

CLINICAL MANIFESTATIONS

• Symptoms may be gradual in onset, over months or years
• Initially May be asymptomatic, or may have mild symptoms, such as feeling very tired or weak.
• Over the year heart gets weaker, develop Congestive heart failure like symptoms
  • Pulmonary congestion (left HF) - Shortness of breath or dyspnea (rest, exertional, nocturnal), orthopnea
  • Systemic congestion (right HF) – edema in legs, nausea, abdominal pain, nocturia
  • Chest pain.
• Symptoms suggestive of a low cardiac output - decreased exercise tolerance and palpitations
• Other are Hypotension, tachycardia, tachypnea, Increase JVP
• Symptoms may get them suddenly, such as after pregnancy or an illness caused by a virus.

DIAGNOSTIC EXAMINATION

• Chest x-ray
• Electrocardiogram
• 24-hour ambulatory ECG (Holter monitoring)
  • lightheadedness, palpitation, syncope
• Two-dimensional echocardiogram
• Radionuclide ventriculography
• Cardiac catheterization
  • age >40, ischemic history, high risk profile, abnormal ECG
• Myocardial biopsy, to make a definite diagnosis

MANAGEMENT

• Goal - relieving symptoms, and the management of heart failure to improving heart function
• Non-pharmacologic therapies include
  • Salt restriction,
  • Exercise,
  • Alcohol cessation,
  • Smoking cessation,
  • Weight reduction
• Drug therapy for heart failure
  • ACE inhibitors – reduced systemic congestion by reducing BP and increase kidneys diuresis
  • β-adrenergic blocker – reduced cardiac workload by redesign HR
  • loop diuretics - relieve volume overload such as edema
  • Anticoagulation – if atrial fibrillation or prior history of thromboembolism
• Patients with left bundle branch block and LV systolic dysfunction –
  • Cardiac resynchronization therapy (pacemaker) or
  • Implantable cardioverter-defibrillator (icd), or
  • Both.
• Surgery - heart transplant may be an option.

Hypertrophic cardiomyopathy (HCM)

Hypertrophic cardiomyopathy ("HCM") is a disease of the myocardium characterized by asymmetrically increases in size and mass (hypertrophied) of myocardium, especially along the septum and non-dilated left ventricle without any obvious cause and exhibit diastolic dysfunction.

INCIDENCE

• DCM is the most rare form of cardiomyopathy
• Prevalence of occurrence of 0.02 to 0.2%
• Occurring in men, women, and children (often detected after puberty)
• Most well known as a leading cause of sudden cardiac death in young athletes
• Younger people are likely to have a more severe form of hypertrophic cardiomyopathy

ETIOLOGY

• Causative factor unknown - called idiopathic DCM
• Hypertrophic cardiomyopathy is a genetic disorder
  • autosomal dominant pattern of inheritance
  • The most common genetic heart disease

CLINICAL MANIFESTATIONS

• Mostly asymptomatic
• When symptoms occur they can be -
  • Exertional dyspnea,
  • Fatigue,
  • Chest pain,
  • Palpitations,
  • Dizziness,
  • Exertional syncope, and
  • Sudden cardiac death

ASSESSMENT AND DIAGNOSTIC FINDINGS

Physical examination -

• Fast rising arterial pulse,
• Pulsus bisferiens (a pulse with double peaks)
• Double apical precordial impulse - The double impulse represents the initial normal outflow, obstruction as systole progresses, and then a second rise in flow as the ventricle relaxes.
• fourth heart sound present
• Murmur - harsh, diamond-shaped systolic murmur best heard at the base

Diagnostic test –

• ECG - shows LV hypertrophy and prominent septal Q waves
• Echocardiography - the definitive diagnostic test, showing
• LV hypertrophy and Asymmetric septal hypertrophy (septal thickness >1.5 times that of posterior wall or >15 mm)
• LV outflow tract obstruction
• Cardiac catheterization - shows an elevated left ventricular diastolic pressure
• Genetic testing for diagnosis and screening
• All first-degree relatives should have a screening echocardiogram every 5 years and for adolescents every year until they are 18 years of age

MANAGEMENT

• The goal of therapy is relief of symptoms and prevention of sudden cardiac death.
• Pharmacological therapy cannot cure hypertrophic cardiomyopathy, but they may be used to treat complications, including atrial fibrillation and heart failure. These medicines include:
  • Beta blockers which can decrease the outflow gradient, improve diastolic filling, and reduce myocardial ischemia by slowing the heart rate.
  • Calcium channel blockers and disopyramide have been used but are not recommended as first-line therapy.
  • Vasodilators such as nitroglycerin should be avoided in patients with HOCM. Patients should be advised to avoid dehydration and strenuous exercise.
  • Disopyramide - Antiarrhythmic, to control the heart rhythm.
  • Prophylactic Anticoagulants – if patient have atrial fibrillation.
• Surgical treatment - cardiac myectomy

Restrictive Cardiomyopathy(RCM)

Restrictive cardiomyopathy (RCM) is least common type of cardiomyopathies characterized by increased stiffness of the myocardium resulting impaired filling of the ventricles in the presence of normal wall thickness and systolic function.

Restrictive cardiomyopathy (RCM) also known as "constrictive cardiomyopathy".

ETIOLOGY

• Loeffler endocarditis
• Endomyocardial fibroelastosis
• Infiltrative disorders
  • Cardiac Amyloidosis
  • Haemosiderosis
  • Sarcoidosis
• Post-radiation fibrosis
• Scleroderma
• Idiopathic
• Genetic

CLINICAL MANIFESTATIONS

• Symptoms of heart failure are most common. Usually, Symptoms may be gradual in onset, over months or years. Sometimes very suddenly and are severe.
• Over the year heart gets weaker, develop Congestive heart failure like symptoms
  • Pulmonary congestion (left HF) - shortness of breath or dyspnea (rest, exertional, nocturnal)
  • Systemic congestion (right HF) – edema in legs, nausea, abdominal pain, nocturia
  • Chest pain.
• Symptoms suggestive of a low cardiac output - decreased exercise tolerance and palpitations
• symptoms may include – Cough, Anorexia, Swelling of the abdomen, Decreased alertness or concentration and oligourea.

ASSESSMENT AND DIAGNOSTIC FINDINGS

Physical examination may show -

• Distended neck veins
• Enlarged liver
• Lung crackles and abnormal or distant heart sounds

Diagnostic test may show -

• ECG - shows sinus tachycardia, nonspecific ST-T changes, and a left bundle branch block.
• Chest X-Ray - shows cardiomegaly and pulmonary venous congestion.
• Echocardiography – may shows LV is thickened and is not dilated
• Cardiac catheterization - shows elevated right and left ventricular end diastolic pressures.
• Endomyocardial biopsy - useful for the diagnosis of amyloidosis, hemochromatosis, and endomyocardial fibrosis.
• Other - Chest CT scan, MRI of the heart, Serum iron studies and Serum or urine protein tests

MANAGEMENT

• Treatment is aimed toward the underlying clinical condition causing RCM and the relief of heart failure symptoms.
• For hemochromatosis, specific treatments include deferoxamine and phlebotomy.
• For amyloidosis - autologous stem cell transplantation, and cardiac transplantation improve survival in certain cases but the overall prognosis remains poor.
• For endomyocardial fibrosis, surgical excision of fibrotic endocardium is an option.
• For cardiac sarcoidosis, corticosteroids may slow the progression but the incidence of ventricular tachycardia is unaffected. An implantable cardioverter defibrillator should be placed in sarcoidosis patients with nonsustained ventricular tachycardia or syncope.
• Diuretics, ACE-inhibitors, Beta-blockers and vasodilators should be used to manage the symptoms of heart failure so that LV preload is not compromised.

NURSING MANAGEMENT

NURSING ASSESSMENT

• History of the presenting signs and symptoms
• The physical assessment focuses on signs and symptoms of heart failure. The baseline assessment includes key components as:
  • Vital signs
  • Calculation of pulse pressure
  • Current weight and any weight gain or loss
  • Detection by palpation of the point of maximal impulse, often shifted to the left
  • Cardiac auscultation for a systolic murmur and S3 and S4 heart sounds
  • Pulmonary auscultation for crackles
  • Measurement of jugular vein distention
  • Assessment of edema and its severity

NURSING DIAGNOSES

• Based on the assessment data, major nursing diagnoses may include:
  • Decreased cardiac output related to structural disorders caused by cardiomyopathy or to dysrhythmia from the disease process and medical treatments
  • Anxiety related to the change in health status and in role functioning
  • Powerlessness related to disease process

NURSING INTERVENTIONS

Improving Cardiac Output

• Monitor heart rate, rhythm, temperature, and respiratory rate at least every 4 hours.
• Evaluate CVP, pulmonary artery wedge pressure, and PCWP by pulmonary artery catheter to assess progress and effect of drug therapy.
• Observe for changes in CO, such as decreased BP, change in mental status, decreased urine output.
• Administer pharmacologic support as directed, and observe for changes in hemodynamic and clinical status.
• Administer medications to control or eradicate dysrhythmias as directed.
• Administer anticoagulants as directed, especially for patients in atrial fibrillation.
  • Monitor coagulation studies.
  • Observe for evidence of bleeding.

Relieving Anxiety

• Always evaluate increasing and/or new onset anxiety for a physiologic cause, and report to the health care provider before administration of anxiolytics.
• Explain all procedures and treatments.
• Inform patient and visitors of visiting hours and policy and whom to contact for information.
• Orient patient to unit, purpose of equipment, and care plan.
• Encourage questions and voicing of fears and concerns.

Reducing Fatigue

• Make sure that patient and visitors understand the importance of rest.
• Assist patient in identifying stressors and reducing their effect (important for patients with hypertrophic cardiomyopathy because stress worsens the outflow obstruction).
• Provide uninterrupted periods, and assist with ambulation as ordered.
• Teach the use of diversional activities and relaxation techniques to relieve tension.

HEALTH EDUCATION

• Teach about medications
• Follow up for periodic blood levels.
• Advise about low-sodium diet.
• Advice reporting signs of heart failure—weight gain, edema, shortness of breath, increased fatigue
• Make sure that family members know cardiopulmonary resuscitation (CPR) because sudden cardiac arrest is possible