Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (58 page)

BOOK: Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis
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   May be confused with restrictive/infiltrative CM or HF. Presence of pericardial thickening and calcification on imaging make the diagnosis more likely, but 18% of patients have normal findings.
   May occur after any pericardial inflammatory process, but rare after pericarditis. Post–cardiac surgery or radiation therapy (Hodgkin lymphoma or breast cancer) accounts for a large percentage of patients (up to 30%). Direct pericardial infections (tuberculous or purulent pericarditis), connective tissue disease, and pericardial involvement of neoplasms are far more likely to cause constriction than pericarditis from viral etiologies.
   In cases where cirrhosis is initially suspected, but no etiology is found via serologic testing. JVP is rarely elevated in cirrhotic patients, and if present, will not persist after pericardiocentesis as it will in constrictive pericarditis.
   Diagnostic and Laboratory Findings
   BNP/NT-proBNP are less elevated than with HF or restrictive cardiomyopathy.
   Echocardiography may establish the diagnosis with respiratory variation in mitral inflow and hepatic vein reversal and pericardial thickening. Biatrial enlargement is more common in myocardial disease than in constriction.
   While often not required for diagnosis, catheterization remains the gold standard of diagnosis demonstrating ventricular interdependence with respiratory maneuvers, which is >90% sensitive and specific for constriction.
SYNCOPE AND SUDDEN CARDIAC ARREST

SYNCOPE

Syncope is a common chief complaint, accounting for up to 6% of all hospital admissions from the emergency department, with one third of people experiencing syncope at some point during their lifetime. While most often self-limited and not associated with poor prognosis, the cardiovascular assessment of patients with syncope must distinguish potentially life-threatening etiologies from benign causes that require no further evaluation or treatment.

   Definition
   Syncope is the paroxysmal and transient loss of consciousness associated with an absence of postural tone with rapid and complete recovery.
   Causes of syncope can be divided into several categories that include arrhythmias, cardiovascular structural abnormalities, orthostatic and neurally mediated responses, cerebrovascular events, and metabolic derangements.
   Syncope must be distinguished from cardiac arrest requiring cardiopulmonary resuscitation and/or cardioversion. The latter warrants extensive evaluation for coronary artery disease, structural heart disease, and possible arrhythmogenic triggers. The two entities are not unrelated, however, with up to one quarter of patients with cardiac syncope with high-risk features having subsequent cardiac arrest at 1 year.

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