Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (57 page)

   
Amyloid cardiomyopathy
: Typically presents as right-sided failure with frank pulmonary edema rare. Anginal may occur from small vessel involvement. Cardiac involvement varies with type of amyloidosis, with 50% in AL (primary) amyloidosis and 5% in secondary (AA) amyloidosis. HF with heavy proteinuria, periorbital purpura, and significant hepatomegaly should raise suspicion. TTR mutation (autosomal dominant) amyloid is present in patients of African descent (3.5%) and presents as late-onset heart failure. LV wall thickening is usually out of proportion to degree of hypertension (>15 mm) and should not be attributed to hypertensive heart disease. Syncope is common, particularly exertional, but high-grade AV block is unusual in AL amyloid (common in TTR). Echo findings of increased wall thickness and reduced ECG voltage are unique to amyloidosis and carry a 72% and 91% sensitivity/specificity. CMR has similar excellent diagnostic yield. BNP may be significantly elevated prior to the onset of heart failure due to amyloid infiltration. Definitive diagnosis requires tissue biopsy—may be from endomyocardial biopsy or fat pad aspirate in other cardiac diagnostic criteria are present.

   
Right ventricular dysfunction
: Most common etiologies of preserved left ventricular function with isolated RV dysfunction include RV myocardial infarction, tricuspid regurgitation, and pulmonary disorders (embolus, pulmonary hypertension—see Chapter
13
, Respiratory Disease).
Arrhythmogenic right ventricular cardiomyopathy
(ARVC) is a rare (1:5,000) autosomal dominant disorder with incomplete penetrance characterized by electrical instability and heightened risk of sudden cardiac death. There is no definitive diagnostic test, but rather, diagnosis requires an integrated assessment of electrical, functional, and anatomic abnormalities. Most commonly, monomorphic VT with a LBBB pattern is seen with focal wall motion abnormalities of the right ventricle in the absence of coronary artery disease. Differential diagnoses may include Brugada syndrome, and endomyocardial biopsy may be required to differentiate between focal infiltrative disorders such as sarcoid and amyloid.

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PERICARDIAL CONSTRICTION

   Definition

   Effusion and tamponade (see above) remain the most common cause of dyspnea due to pericardial disease; however, constriction of the pericardial space due to fibrosis of the inelastic pericardium is an important contribution to dyspnea as surgical pericardiectomy is potentially curative.

   Pericardial constriction is typically chronic but may present acutely.

   Effusive–constrictive pericarditis is a variant that presents often as tamponade but exhibits hemodynamic constriction after pericardiocentesis (ventricular interdependence).

   Who Should Be Suspected?

   Patients with fatigue and dyspnea in the context of clinical evidence of right-sided failure and congestion. Anorexia and abdominal distention are frequent. It is not uncommon for patients to have undergone hepatobiliary evaluation prior to diagnosis.

   Exam may be notable for a pericardial knock (diastole) and prominent X and Y descent of the jugular venous pulsation especially during inspiration (Kussmaul sign).