11 Selected Disorders of the Cardiovascular SystemDavid E. AnismanPericarditisPericarditis may be divided into two typesacute and constrictive. Acute pericarditis (AP), which is an inflammatory condition of the membranes lining the heart, affects men more frequently than women, and is seen with increasing frequency with advancing age. While AP is diagnosed in less than 1% of hospital admissions, it has an estimated prevalence of 2% to 6% in the general population, un- derscoring the frequency with which it is either clinically not ap- parent or not considered in the differential diagnosis.1The most com- mon etiologies are idiopathic, viral (which may actually account for most idiopathic cases), and in association with cardiac ischemia (Table 11.1). Indeed, the chest pain associated with AP may make it difficult to distinguish from acute myocardial ischemia. Constric- tive pericarditis (CP), formerly known as Picks disease, is charac- terized by a thickened, adherent, and fibrous pericardium that im- pairs diastolic filling, leading to the gradual onset of symptoms consistent with systemic venous congestion, such as congestive heart failure (CHF). It is a postinflammatory sequela of many of the same etiologies as AP, but the clinician should always maintain a high suspicion for tuberculosis, which is still the leading cause of CP in developing countries.2Presentation and Diagnosis Acute pericarditis may be heralded by a viral prodrome, and classi- cally presents with a triad of chest pain, pericardial friction rub, and characteristic electrocardiographic (ECG) changes. The chest pain is usually rather abrupt in onset, retrosternal in location, and made worse with recumbency, deep inspiration, and swallowing. It is often eased by sitting up and leaning forward. The pain may radiate to the trapez- ius ridge, or may mimic the pain of acute myocardial ischemia with radiation into the left arm. Respiratory symptoms are generally the result of secondary pleural irritation rather than a primary effect of AP on cardiac function. The pathognomonic pericardial friction rub is classically described as triphasic (atrial systole, ventricular systole, and diastole), with the ventricular systolic component most readily and most often heard. The rub is scratchy or “Velcro-like” and best heard with the patient sitting upright and leaning forward, with res- pirations interrupted, and by placing the diaphragm over the left lower sternal border and cardiac apex. Confusion with murmurs can be avoided by recognizing that the rub does not radiate or vary in either loudness or timing with maneuvers that typically are used for mur- mur identification. The four classic stages of ECG changes in AP are summarized in Table 11.2; not all phases need be present to confirm the diagnosis.11. Selected Disorders of the Cardiovascular System257Table 11.1. Etiologies of PericarditisInfectious Bacterial: pneumococcus, staphylococcus, Neisseria meningitidis, streptococcus, mycoplasma, tuberculosis, Haemophilus influenzae, rickettsia Viral: coxsackie, echovirus, adenovirus, influenza, varicella-zoster, HIV Fungal: histoplasmosis, aspergillosis, blastomycosis, coccidioidomycosis Trauma: blunt chest trauma, post-thoracic surgery Medications: procainamide, phenytoin, isoniazid, penicillin, heparin, warfarin, cromolyn sodium, methysergide Cardiac: AMI, Dresslers syndrome, endocarditis, aortic dissection Radiation therapy Neoplastic: breast, bronchogenic lung, lymphoma, leukemia Uremia: poorly controlled or while on hemodialysis Autoimmune: systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel, acute rheumatic fever, scleroderma, polyarteritis nodosa, dermatomyositis Other: sarcoidosis, amyloidosisAMI ? acute myocardial infarction.Because PR segment depression may coexist with ST segment ele- vation, it is crucial to use the TP segment as a baseline.3Acute peri- carditis may be differentiated from acute myocardial infarction (AMI) by the diffuseness of ST changes, the absence of Q waves, and the characteristically concave up-sloping morphology of the ST segment. Benign early repolarization (BER) also may present with diffusely elevated ST segments, but use of the ST/T ratio (Fig. 11.1) is help- ful in making the distinction. Because of the wide variety of presenting signs and symptoms, CP is difficult to diagnose solely on history and physical examination.2 Symptoms of right-sided CHF, such as abdominal distention, pe- ripheral edema, and anorexia reflect impaired diastolic filling and chronically depressed cardiac output. Left-sided CHF symptoms such as dyspnea and orthopnea also occur, but are less frequent.4Com- mon ex-amination findings include Kussmauls sign (jugular venous pressure increasing with inspiration), ascites, cachexia, hepato- megaly, and a pericardial knock (an early diastolic sound heard best with the diaphragm and increased with squatting). Though rarely nor- mal, the ECG findings are nonspecific, revealing