Page 753 - Cardiac Nursing

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C HAPTER 30 / Pericardial, Myocardial, and Endocardial Disease 729
multiple infections, may play a role in the pathogenesis of DCM DCM. 54 Medications identified through clinical trials as provid-
far more frequently than suspected so far. 49 Another study found ing beneficial effects for patients with DCM include diuretics, an-
that adenovirus was the most common virus in the myocardium giotensin-converting enzyme (ACE) inhibitors or angiotensin re-
of children and adults with myocarditis and DCM. 50 Secondary ceptor blockers if ACE intolerant, and -blockers. 54 A recent
causes of DCM include CAD, myocarditis, nutritional defi- study showed that -blocker therapy (carvedilol) induced signifi-
ciency, systemic disease, cardiotoxins, puerperium, alcohol, and cant reductions in intraventricular dyssynchrony and improved
skeletal muscle wasting diseases. 46 contractility in DCM patients with heart failure and normal
QRS. 55 Another study of the -blocker carvedilol showed an im-
Pathophysiology provement in coronary flow reserve and a reduction in stress-in-
DCM is characterized by an increase in myocardial mass and a re- duced perfusion defects. These results suggest a favorable effect of
duction in ventricular wall thickness. The heart assumes a globu- the drug on coronary microvascular function in patients with id-
lar shape and there is pronounced ventricular chamber dilatation, iopathic DCM. 56
diffuse endocardial thickening, and atrial enlargement often with Successful treatment of the patient with alcoholic cardiomy-
thrombi in the appendages. 46 The histological changes seen in opathy must include cessation of alcohol consumption, which can
41
DCM are nonspecific. Familial DCM is caused by mutations in have significant benefits in improving symptoms of heart failure.
structural proteins comprising the myocyte cytoskeleton or sar- Ongoing alcohol consumption significantly worsens the patient’s
colemma. 46 Intraventricular conduction delay and LBBB com- prognosis. Additional therapy includes a regimen of neurohor-
monly occur in patients with idiopathic DCM. When cardiomy- monal blockers. Administration of thiamine is also indicated in
opathy causes left ventricular failure, conduction abnormalities the possibility that malnutrition may play a role in the presenta-
add further to LV dysfunction by compounding dyssynchrony in tion. Anticoagulation should only be considered in the presence
the contractile motion of the LV wall. 51 of a clear-cut and pressing indication because of the increased risk
of trauma, catastrophic bleeding, and increased anticoagulation
Assessment Findings caused by hepatic dysfunction related to alcohol abuse. 52
Presentation of DCM is usually with heart failure, which is often In research on patients with severe, nonischemic DCM who
progressive. The most typical symptoms include dyspnea, fatigue, were treated with ACE inhibitors and -blockers, the implanta-
and volume gain. A minority of patients report chest pain, which tion of a cardioverter defibrillator significantly reduced the risk of
can signify epicardial coronary disease, subendocardial disease, or sudden death from arrhythmia. 57 This intervention has become
pulmonary embolism. Arrhythmias, thromboembolism, and sud- an important mainstay of treatment. Cardiac resynchronization
den death are common, and may occur at any stage during the therapy (CRT) with biventricular pacing has emerged as a prom-
disease. 41 Complaints of abdominal discomfort or anorexia are ising treatment for medically refractory heart failure. 55 CRT cor-
frequent in late stages of the disease and suggest hepatomegaly or rects dyssynchrony by synchronous pacing from transvenous pac-
bowel edema, respectively. Other common late complications in- ing catheters implanted in the right atrium and right ventricle.
clude thromboembolic events, which may be systemic, originating The CRT device usually includes an implantable defibrillator. 51
from the left atria and ventricle, or pulmonary thrombi from the Patients with valvular heart disease, CHD, pericardial disease,
lower extremities. 52 Mitral regurgitation is common in DCM, as or congenital heart defects should be considered for surgical cor-
are ventricular arrhythmias, particularly ventricular tachycardia, rection. There are also other surgical approaches to DCM de-
torsades de pointes, and ventricular fibrillation. 42 A recent study signed to restore chamber geometry or provide mechanical sup-
found strong evidence that glucose intolerance is a common char- port. Procedures aimed at surgically remodeling of the heart
acteristic of patients with idiopathic DCM. 53 include left ventricular reconstruction or implantation of external
Echocardiography is a cornerstone in the evaluation and man- restraint devices. The CorCap Cardiac Support Device (Acorn
agement of patients with DCM. Two-dimensional echocardiogra- Cardiovascular, Inc., St Paul, MN), one implanted device de-
phy is a valuable noninvasive technique to assess ventricular size signed to provide support for the heart, was recently tested in a
and performance, and to evaluate associated valvular or pericardial study funded by the developers to see if it improved heart failure
abnormalities. Doppler echocardiography allows the evaluation of in patients with DCM by preventing LV remodeling. This initial
valvular regurgitation or stenosis, and the quantification of cardiac safety and efficacy trial of this device showed promising results. 58
52
output. This important information regarding the patient’s con- Left ventricular assist devices provide aggressive mechanical sup-
dition helps guide therapy. port to patients with advanced decompensated heart failure. 54
Cardiac catheterization usually reveals increased left ventricu- DCM is a leading reason for cardiac transplantation. 59 Al-
lar end-diastolic pressures and pulmonary artery wedge pressures. though the incidence of ischemic cardiomyopathy is higher than
Pulmonary hypertension may range from mild to severe. The DCM, these two diagnoses account for an equal number of per-
right ventricle is frequently involved and enlarged, manifested formed cardiac transplantations. Cardiac transplantation becomes
with increased right ventricular end-diastolic pressures, right atrial a possible treatment option when all medical therapies have been
pressures, and central venous pressures. 52 maximized, and no other surgical procedures will correct the un-
derlying disease process. 60
Medical Management Recently new guidelines for management of heart failure were
The initial evaluation of patients presenting with DCM should published in Europe and in the United States detailing medica-
focus on identifying reversible and secondary causes. 52 Medical tion management guidelines and clinical testing. The recommen-
management focuses on optimizing cardiac function. Treatment dations also include patient and family counseling, weight man-
with neurohormonal antagonists to prevent disease progression agement and monitoring, dietary measures including sodium
and the use of diuretics to maintain the volume balance are the restriction, fluid management, exercise as tolerated, smoking ces-
therapeutic cornerstones for the management of patients with sation, and immunization for influenza. 54,61