Final The Echo Manual DIGITAL

Chapter 12 Pericardial Diseases

CHAPTER 12 PERICARDIAL DISEASES

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namic abnormalities specific to constriction and include comprehensive echocardiography (6,7,26,31,32) and inva- sive hemodynamic cardiac catheterization, with simultane- ous recording of the respiratory cycle (33,34). The M-mode and 2D echocardiographic features of constrictive pericarditis include a thickened pericardium, respirophasic abnormal ventricular septal motion, flat- tening of the LV posterior wall during diastole, respiratory variation in ventricular size, and a dilated inferior vena cava (Fig. 12-18). However, these findings are not decisive for the diagnosis. Hatle and colleagues (31) described the seminal Doppler features of constriction that are distinct from those of restrictive myocardial disease. They reflect the following pathophysiologies: 1) dissociation between intrathoracic and intracardiac pressures and 2) exagger- ated ventricular interdependence. To establish the diag- nosis of constrictive pericarditis, these two hemodynamic disorders must be demonstrated. A noncompliant, adherent pericardium prevents full transmission of the intrathoracic pressure changes that occur with respiration to the intracardiac cavities. With inspiration, intrathoracic pressure falls (normally 3–5 mm Hg) and the pressure in other intrathoracic struc- tures (pulmonary veins, pulmonary capillaries) decreases to a similar degree. Since the noncompliant pericardium shields the cardiac chambers from this inspiratory pressure decline, the pressure difference between the pulmonary n

many patients undergo noncardiac procedures such as liver biopsy, endoscopy, and even abdominal exploration for suspected liver or other gastrointestinal disease before constrictive pericarditis is diagnosed. Confirmation of constrictive pericarditis had been chal- lenging, but with the application of blood flow and tissue velocity Doppler imaging as well as M-mode and 2-D echo- cardiography, constrictive pericarditis can be diagnosed and distinguished from myocardial disease with high sensitiv- ity and specificity (26). In contrast, pericardial calcification on chest radiography occurs in only 23% of patients (27) (Fig. 12-17). The identification of a thick pericardium by tomographic imaging is typical with constriction, but peri- cardial thickness may be normal in nearly 20% of patients (28). Furthermore, a thickened or calcified pericardium does not by itself indicate hemodynamically significant constriction. Traditional invasive hemodynamic abnor- malities of constriction may overlap with those of restric- tive cardiomyopathy or other intrinsic myocardial diseases (29). B-type natriuretic peptide levels tend to be lower (or even normal) in constrictive pericarditis than in restrictive myocardial disease but cannot reliably distinguish the two disorders, particularly in patients with mixed myocardial and pericardial diseases (30). Thus, the diagnosis of con- striction should be based on its characteristic hemodynam- ics. The diagnostic studies, which most reliably identify constrictive pericarditis, detect the respirophasic hemody-

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FIGURE 12-17 Lateral ( left ) and posteroanterior ( right ) chest radiographs showing pericardial calcification ( arrows ). Calcification is most common in the diaphragmatic portion of the pericardium.

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