Dilated Cardiomyopathy

Question 1

What is the pathophysiology of dilated cardiomyopathy?

Answer 1

Dilated cardiomyopathy (DCM) is the structural abnormality most commonly seen. DCM involves extensive damage to the myofibrils and interference with myocardial metabolism. Ventricular wall thickness is normal, but both ventricles are dilated (left ventricle is usually worse) and systolic function is impaired.

Question 2

What are some causes of dilated cardiomyopathy?

Answer 2

Causes may include alcohol abuse, chemotherapy, infection, inflammation, and poor nutrition. Decreased CO from inadequate pumping of the heart causes the patient to experience dyspnea on exertion (DOE), decreased exercise capacity, fatigue, and palpitations.

Question 3

What are the signs and symptoms associated with dilated cardiomyopathy?

Answer 3

• Fatigue and weakness
• Heart failure (left side)
• Dysrhythmias or heart block
• Systemic or pulmonary emboli
• S3 and S4 gallops
• Moderate to severe cardiomegaly
• Symptoms of left ventricular failure, such as progressive dyspnea on exertion, orthopnea, palpitations, and activity intolerance.

Question 4

What treatment is associated with dilated cardiomyopathy?

Answer 4

• Symptomatic treatment of heart failure
• Vasodilators
• Control of dysrhythmias
• Surgery: heart transplant

Question 5

What diagnostics are done?

Answer 5

Echocardiography, radionuclide imaging, and angiocardiography during cardiac catheterization are performed to diagnose and differentiate cardiomyopathies

Question 6

What are nonsurgical management interventions?

Answer 6

Drug therapy includes the use of diuretics, vasodilating agents, and cardiac glycosides to increase CO. Because patients are at risk for sudden death, teach them to report any palpitations, dizziness, or fainting, which might indicate a dysrhythmia. Antidysrhythmic drugs or implantable cardiac defibrillators may be used to control life-threatening dysrhythmias. To block inappropriate sympathetic stimulation and tachycardia, beta blockers (e.g., metoprolol) are used. If cardiomyopathy has developed in response to a toxin (such as alcohol), further exposure to that toxin must be avoided.

Question 7

What are surgical management interventions?

Answer 7

Heart transplantation

Question 8

What preoperative care is included prior to surgical intervention?

Answer 8

Criteria for candidate selection for heart transplantation include:
* Life expectancy less than 1 year
* Age generally younger than 65 years
* New York Heart Association (NYHA) Class III or IV
* Normal or only slightly increased pulmonary vascular resistance
* Absence of active infection
* Stable psychosocial status
* No evidence of current drug or alcohol misuse

Question 9

What is involved in the heart transplantation surgery?

Answer 9

The surgeon transplants a heart from a donor with a comparable body weight and ABO compatibility into a recipient less than 6 hours after procurement. In the most common procedure (bicaval technique), the intact right atrium of the donor heart is preserved by anastomoses at the patient’s (recipient’s) superior and inferior venae cavae. In the more traditional orthotopic technique, cuffs of the patient’s right and left atria are attached to the donor’s atria. Anastomoses are made between the recipient and donor atria, aorta, and pulmonary arteries (Fig. 32.7). Because the remaining remnant of the recipient’s atria contains the sinoatrial (SA) node, two unrelated P waves are visible on the ECG.

Question 10

What postoperative care is included after the surgical procedure?

Answer 10

• The postoperative care of the heart transplant recipient is similar to that for conventional cardiac surgery. However, the nurse must be especially observant to identify occult bleeding into the pericardial sac with the potential for tamponade. The patient’s pericardium has usually stretched considerably to accommodate the diseased, hypertrophied heart, predisposing the patient to concealed postoperative bleeding.
• The transplanted heart is denervated (disconnected from the body’s autonomic nervous system) and unresponsive to vagal stimulation. In the early postoperative phase, isoproterenol may be titrated to support the heart rate and maintain cardiac output. Atropine, digoxin, and carotid sinus pressure are not used because they do not have their usual effects on the new heart. Denervation of the heart may cause pronounced orthostatic hypotension in the immediate postoperative phase. Caution the patient to change position slowly to help prevent this complication. Some patients also require a permanent pacemaker that is rate responsive to his or her activity level. The purpose is to increase CO and improve activity tolerance.
• To suppress natural defense mechanisms and prevent transplant rejection, patients require a combination of immunosuppressants for the rest of their lives. Chapter 16 describes transplant rejection and prevention in detail.
• Be very careful about handwashing and aseptic technique because patients are immunosuppressed from drug therapy. Infection is the major cause of death and usually develops in the immediate post-transplant period or during treatment for acute rejection.
• The median survival rate for adults following cardiac transplantation is 11 years and rising. Over time, many of these surviving patients are developing a form of coronary artery disease (CAD) called cardiac allograft vasculopathy (CAV), which presents as diffuse plaque in the arteries of the donor heart. The cause is thought to involve a combination of immunologic and nonimmunologic processes that result in vascular endothelial injury and an inflammatory response. Because the heart is denervated, patients do not usually experience angina. Regularly scheduled exercise tolerance tests and angiography are required to identify CAV. Only a small percentage of patients with CAV benefit from revascularization procedures such as balloon angioplasty or coronary artery bypass surgery. Stents are beginning to show some promise in managing these patients. Retransplantation may be done in select patients.
• To delay the development of CAD encourage patients to follow lifestyle changes similar to those with primary CAD. The provider may prescribe a calcium channel blocker such as diltiazem to prevent coronary spasm and closure. Stress the importance of strict adherence to nutritional modifications and drug regimens. Teach the patient the importance of participating in a regular exercise program. Collaborate with the physical therapist and the cardiac rehabilitation specialist to plan the most appropriate exercise plan for the patient.
• Discharge planning involves a collaborative, interdisciplinary approach. Patients require extensive health teaching for self-management and community resources for support. Counseling and support groups can help patients cope with their fear of organ rejection. Drug therapy adherence is crucial to prevent this problem. Continuing community-based care for patients with a heart transplant is similar to that for heart failure discussed earlier in this chapter.

Question 11

What are some signs and symptoms of heart transplant rejection?

Answer 11

• Shortness of breath
• Fatigue
• Fluid gain (edema, increased weight)
• Abdominal bloating
• New bradycardia
• Hypotension
• Atrial fibrillation or flutter
• Decreased activity tolerance
• Decreased ejection fraction (late sign