Page 755 - Cardiac Nursing

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C HAPTER 30 / Pericardial, Myocardial, and Endocardial Disease 731
Restrictive Cardiomyopathy Assessment Findings
Presentation of ARVC with arrhythmias and sudden death is
RCM is characterized by restrictive filling and reduced diastolic common, particularly in the young, and may be precipitated by
volume of either or both ventricles with normal or near-normal exertion. 41,46 ARVC accounts for up to 20% of cases of sudden
systolic function and wall thickness. 41 It is an uncommon type of cardiac death, and, importantly, among young athletes dying sud-
cardiomyopathy in countries like the United States. 73 54
denly, the prevalence of this condition is high.
The most common ECG abnormalities found in a U.S. cohort
Etiology of ARVC patients were delayed S-wave upstroke and T-wave inver-
RCM may be idiopathic, or associated with other diseases, such as sion. Thirty-one of 100 patients in this cohort experienced sudden
amyloidosis, and endomyocardial fibrosis. 41,73,74
cardiac death. Arrhythmic events are thought to be the most im-
portant events in ARVC, substantiated by the results in this cohort
Pathophysiology in which the prognosis was excellent once an ICD was instituted. 77
The pathophysiological feature that defines RCM is an increase in Another study showed that due to effective treatment of arrhyth-
stiffness of the ventricular walls, which causes impaired diastolic mias leading to sudden cardiac death, heart failure has emerged as
filling of the ventricle and heart failure. In RCM, interstitial fi- an another major cause of death in patients with this disorder. 78
brosis may be present. 41 In early stages of RCM, systolic function
may be normal, although deterioration in systolic function is usu- Medical Management
ally observed as the disease progresses. 52
The diagnostic criteria for ARVC involve features obtained from
imaging, ECG, signal-averaged ECG and histological criteria, as
Assessment Findings well as a positive family history and a history of arrhythmias. En-
Clinically, RCM mimics constrictive pericarditis. Symptoms include domyocardial biopsy may offer valuable diagnostic information,
weakness, dyspnea, edema, and exertional chest pain. Patients with but cardiac MRI is emerging as a more definitive diagnostic
RCM frequently present with exercise intolerance because of an im- tool. The main limitations of endomyocardial biopsy are a high
76
paired ability to augment cardiac output during increasing heart rate false-negative rate because of sampling error, and absence from the
because of the restriction of diastolic filling. With advanced disease, right ventricular of the characteristic histological changes. Re-
profound edema occurs that includes peripheral edema, he- searchers have reported that characterization of the ventricular
52
patomegaly, ascites, and anasarca. Physical examination reveals an wall morphology with delayed enhancement gadolinium MRI
elevated jugular venous pulse, often with the Kussmaul’s sign, and an correlated with histological findings and with inducibility of ven-
increasing jugular pressure during inspiration due to the restriction tricular tachycardia during electrophysiological testing. 76
to filling. Both S 3 and S 4 heart sounds are common and the apical Patients diagnosed with ARVC generally require an ICD. An-
pulse is palpable (in contrast to constrictive pericarditis). Patients tiarrhythmic therapy is appropriate prior to ICD insertion. Neu-
with RCM often develop atrial fibrillation. CT and MRI are valu- rohormonal blockade with ACE inhibitors and -adrenoreceptor
able for differentiating constrictive and restrictive disease.
antagonists is also recommended therapy. In individuals progress-
ing to overt heart failure, management involves the same princi-
Medical Management ples for the treatment of other forms of cardiomyopathy. 79 Con-
There is no known treatment for RCM, so therapy is supportive. sideration of heart transplantation is indicated for patients overt
It includes diuretics, corticosteroids, or anticoagulants, depending cardiac failure. 54
on the etiology and manifestations. Cardiac pacing may improve
symptoms 75
Myocarditis
Arrhythmogenic Right Ventricular Myocarditis is an inflammatory disease of the myocardium. My-
Cardiomyopathy ocarditis can be categorized as acute or chronic, and can lead to the
8
development of DCM. Myocarditis may be idiopathic, infectious,
Arrhythmogenic right ventricular cardiomyopathy (ARVC) is also or autoimmune. 44 Primary or postviral myocarditis can be catego-
known as arrhythmic right ventricular dysplasia. ARVC is charac- rized by its clinical pathological manifestations. This includes ful-
terized by progressive fibrofatty replacement of right ventricular minant, chronic active, eosinophilic, and giant cell myocarditis. 80
myocardium, initially with typical regional and later global right Fulminant myocarditis has a 2-week course, resulting either in full
and some left ventricular involvement, with relative sparing of the recovery, or death. Patients with chronic active myocarditis have on-
septum. 41 going inflammation and fibrosis, leading to RCM. Patients treated
for the eosinophilic disorder respond to treatment. Giant cell my-
Etiology ocarditis has a very poor prognosis despite aggressive treatment. 80
Familial disease is common in ARVC, typically with autosomal
dominant inheritance and incomplete penetrance. A recessive Etiology
form has also been identified. 41,54 Several genes and gene loci are There are many etiologies of myocarditis. The cause may be viral,
associated with ARVC. bacterial, fungal, protozoal, and parasitic. Toxins, hypersensitivity
to medications, and immunological syndromes can also cause
Pathophysiology myocarditis. 81 Viruses are considered the predominant cause.
The fibrofatty mechanism of this disease leads to the progressive Age-related and regional differences may be important when look-
81
loss of myocytes. 46 ARVC may also involve the left ventricle. 46 ing at the viral etiology of myocarditis. HIV-related myocarditis
Structural and functional abnormalities of the right ventricle lead is a significant problem for that patient population. Smallpox vac-
to arrhythmias and progressive right ventricular failure. 76 cination has also been associated with myocarditis. 82