CARDIOMYOPATHY

CARDIOMYOPATHY

Cardiomyopathy is a heart muscle disease associated with cardiac dysfunction. It is classified according to the structural and functional abnormalities of the heart muscle:

v Dilated cardiomyopathy(DCM),

v Hypertrophic cardiomyopathy (HCM),

v Restrictive or constrictive cardiomyopathy,

v Arrhythmogenic right ventricular cardiomyopathy (ARVC), and

v Unclassified cardiomyopathy (Richardson et al., 2006).

Ischemic cardiomyopathy is a term frequently used to describe an enlarged heart caused by coronary artery disease, which is usually accompanied by heart failure.

Regardless of the category and the cause, cardiomyopathymay lead to severe heart failure, lethal dysrhythmias,and death.

Epidemiology

Cardiomyopathy causes more than 27,000 deaths each year in the United States, The mortality rate is highest for African Americans and the elderly(American Heart Association, 2001).

TYPES

PRIMARY : aetiology usually unknown

SECONDARY : Aetiology known. Usually secondary to a disease process or condition.

  

Dilated Cardiomyopathy

DCM is the most common form of cardiomyopathy. DCM is distinguished by significant dilation of the ventricles without significant concomitant hypertrophy (i.e. increased muscle wall thickness) and systolic dysfunction. DCM was formerly named congestive cardiomyopathy, but DCM may exist without signs and symptoms of congestion.

Microscopic examination of the muscle tissue shows diminished contractile elements of the muscle fibers and diffused necrosis of myocardial cells which result is poor systolic function. These structural changes decrease the amount of blood ejected from the ventricle with systole, increasing the amount of blood remaining in the ventricle after contraction. Less blood is then able to enter the ventricle during diastole, increasing end-diastolic pressure and eventually increasing pulmonary pressures. Altered valve function can result from the enlarged stretched ventricle, usually resulting in regurgitation. Embolic events caused by ventricular and atrial thrombi as a result of the poor blood flow through the ventricle may also occur.

Causes

v Pregnancy

v Heavy alcohol intake

v Viral infection(e.g. influenza)

v Idiopathic (when the causative factor is unknown).

Early diagnosis and treatment can prevent or delay significant symptoms and sudden death from DCM.

Hypertrophic Cardiomyopathy

In HCM, the heart muscle increases in size and mass, especially along the septum, the increased thickness of the heart muscle reduces the size of the ventricular cavities and causes the ventricles to take a longer time to relax, making it more difficult for the ventricles to fill with blood during diastole and more dependent on atrial contraction for filling. The increased septal size may misalign the papillary muscles so that the septum and mitral valve obstruct the flow of blood from the left ventricle into the aorta during ventricular contraction.

Hence, HCM may be obstructive or non-obstructive. Because of the structural changes, HCM had also been called idiopathic hypertrophic sub aortic stenosis (IHSS) or asymmetric septal hypertrophy (ASH). Structural changes may also result in a smaller than normal ventricular cavity and a higher velocity flow of blood out of the left ventricle into the aorta, which may be detected by echocardiography. HCM may cause significant diastolic dysfunction, but systolic function can be normal or high, resulting in a higher than normal ejection fraction.

Because HCM is a genetic disease, family members are observed closely for signs and symptoms indicating development of the disease. HCM is rare, occurring in men, women, and children (often detected after puberty).

CAUSES

It may also be idiopathic (i.e., no cause can be found).

RESTRICTIVE CARDIOMYOPATHY

Restrictive cardiomyopathy (RCM) is characterized by diastolic dysfunction caused by rigid ventricular walls that impair ventricular stretch and diastolic filling. Systolic functions usually normal. Because RCM is the least common cardiomyopathy, representing approximately 5% of pediatric cardiomyopathies, its pathogenesis is the least understood. Restrictive cardiomyopathy can be associated with amyloidosis (In which amyloid, a protein substance, is deposited within the cells) and other such infiltrative diseases.

CAUSES

The cause is unknown in most cases (i.e. idiopathic).

ARRHYTHMOGENIC RIGHT VENTRICULAR CARDIOMYOPATHY

ARVC occurs when the myocardium of the right ventricle is progressively infiltrated and replaced by fibrous scar and adipose tissue. Initially, only localized areas of the right ventricle are affected, but as the disease progresses, the entire heart is affected. Eventually, the right ventricle dilates and develops poor contractility, right ventricular wall abnormalities, and dysrhythmias. ARVC should be suspected in patients with ventricular tachycardia originating in the right ventricle or in sudden death, especially among previously symptom-free athletes (Spirito et al., 2000).

CAUSES

The disease may be genetic (i.e. autosomal dominant)

UNCLASSIFIED CARDIOMYOPATHIES

                                                                                                

Unclassified cardiomyopathies are different from or have characteristics of more than one of the previously described cardiomyopathies. Examples of unclassified cardiomyopathies include fibroelastosis, non-compacted myocardium, systolic dysfunction with minimal dilation, and mitochondrial involvement.

PATHOPHYSIOLOGY

The pathophysiology of all cardiomyopathies is a series of progressive events that culminate in impaired cardiac output. Decreased stroke volume stimulates the sympathetic nervous system and the renin-angiotensin- aldosterone response, resulting in increased systemic vascular resistance and increased sodium and fluid retention, which places an increased workload on the heart.

CLINICAL MANIFESTATIONS

v Paroxysmal nocturnal dyspnea

v Dyspnoea (with exertion)

v Orthopnea

v Chest pain

v Palpitations

v Fatigue

v Dizziness

v Nausea

v Syncope with exertion

v Fluid retention

v Peripheral edema

v Cardiac arrest

POTENTIAL COMPLICATIONS

Based on the assessment data, potential complications include:

v  Congestive heart failure

v  Ventricular dysrhythmias

v  Atrial dysrhythmias

v  Cardiac conduction defects

v  Pulmonary or cerebral embolism

v  Valvular dysfunction

ASSESSMENT AND DIAGNOSIS

Physical examination in the early stage may reveal:

v Tachycardia

v Crackles on pulmonary auscultation,

v Jugular vein distention,

v Pitting edema of dependent body parts,

v Enlarged liver

DIAGNOSIS

v Echocardiogram: it reveals the structure and function of the ventricles.

v ECG: demonstrates dysrhythmias and changes consistent with left ventricular hypertrophy.

v Chest x-ray film: reveals heart enlargement and possibly pulmonary congestion.

v Cardiac catheterization: is use to rule out coronary artery disease.

v Endomyocardialbiopsy: is performed to analyze myocardial tissue cells.

MEDICAL MANAGEMENT

Medical management is directed toward determining and managing possible underlying or precipitating causes; correcting the heart failure with medications, a low-sodium diet, and an exercise rest regimen and controlling dysrhythmias with antiarrhythmic medications and possibly with an implanted electronic device, such as an implantable cardioverter-defibrillator

SURGICAL MANAGEMENT

When heart failure progresses and medical treatment is no longer effective, surgical intervention is considered.

v Left Ventricular Outflow Tract Surgery.

v Heart Transplantation.

v Mechanical Assist Devices and

v Total Artificial Hearts: are designed to replace both ventricles. Some require the removal of the patient’s heart to implant the total artificial heart; others do not.

NURSING MANAGEMENT

Assessment

v Detailed history of the presenting signs and symptoms.

v Vital signs

v Calculation of pulse pressure and identification of pulsusparadoxus

v Current weight; determination of weight gain or loss

v Cardiac auscultation for a systolic murmur and third and fourth heart sounds

v Pulmonary auscultation for crackles

v Identification of presence and severity of edema

Nursing Diagnoses

Based on the assessment data, major nursing diagnoses for the patient may include:

v Decreased cardiac output related to structural disorders caused by cardiomyopathy or to dysrhythmia from the disease process and medical treatments

v Ineffective cardiopulmonary, cerebral, peripheral, and renal tissue perfusion related to decreased peripheral blood flow(resulting from decreased cardiac output)

v Impaired gas exchange related to pulmonary congestion caused by myocardial failure (decreased cardiac output)

v Activity intolerance related to decreased cardiac output or excessive fluid volume, or both

v Anxiety related to the change in health status and in role functioning

v Powerlessness related to disease process

v Noncompliance with medication and diet therapies

Planning and Goals

The major goals for the patient include:

v Improved or maintained cardiac output,

v Increased activity tolerance,

v Reduction of anxiety,

v Adherence to the self-care program,

v Increased sense of power with decision making, and

v Absence of complications.

Nursing Interventions

Improving Cardiac Output

v Place patient in a comfortable position.

v Encourage rest.

v Administer O₂ if indicated

v Serve low salt diet

v Encourage change in position to aid circulation.

Increasing Activity Tolerance

v Plan patient’s activities

v Encourage sitting

v Avoid strenuous exercise

v Ensure patient recognizes the symptoms that indicate the need for rest.

Reducing Anxiety

v Spiritual, psychological, and emotional support may be indicated for the patient and significant others.

v Alleviate perceived stressors.

v Provide the patient with appropriate information about cardiomyopathy and self-management activities.

v Provide an atmosphere in which the patient feels free to verbalize concerns.

Promoting Home and Community-Based Care

v Teaching Patients Self-Care.

v Continuing Care: encourage patient to acknowledge changes in lifestyle, effects of medications, and the possibility

Evaluation

Expected Patient Outcomes

Expected patient outcomes may include:

1.     Maintains or improves cardiac function

v Exhibits heart and respiratory rates within normal limits

v Reports decreased dyspnea and increased comfort; maintains or improves gas exchange

v Reports no weight gain

v Maintains or improves peripheral blood flow

2.     Maintains or increases activity tolerance

v Carries out activities of daily living (e.g. brushes teeth, feeds self)

v Reports increased tolerance to activity

3.     Less anxious

v Discusses prognosis freely

v Verbalizes fears and concerns

v Participates in support groups if appropriate

4.     Decreases sense of powerlessness

v Identifies emotional response to diagnosis

v Discusses the control he or she has in life

5.     Adheres to the self-care program

v Takes medications according to prescribed schedule

v Modifies diet to accommodate sodium and fluid restrictions

v Modifies lifestyle to accommodate recommended activity and rest behaviors

v Identifies signs and symptoms to be reported to the health care professional

REFERENCES

American Heart Association.(2001). Heart and stroke statistical update. Dallas, TX: American Heart Association.

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Dajani, A. S., Taubert, K. A., Wilson, W., Bolger, A. F., Bayer, A.,Ferrieri, P., et al. (1997). Prevention of bacterial endocarditis.Circulation, 96(1), 358–366.

McRae, A. I., Chung, M. K., & Asher, C. R. (2001).Arrhythmogenic right ventricular cardiomyopathy: A cause of sudden death in young people. Cleveland Clinic Journal of Medicine, 68(5), 459–467.

Morse, C. J. (2001). Advance practice nursing in heart transplantation.  Progress in Cardiovascular Nursing, 16(1), 21–24, 38.

Nagel, B. M., & O’Keefe, L. M. (1999).Closing in on mitral valve disease.Nursing, 99 (Critical Care 4), 32cc1–2, 4–7

Oakley, C. (1997). Aetiology, diagnosis, investigation, and management of the cardiomyopathies.British Medical Journal, 315(7121), 1520–1524.

Reynan, K. (1996). Frequency of primary tumor of the heart.AmericanJournal Cardiology, 77(1), 107.

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