Doppler echocardiography has greatly facilitated the assessment of patients with compressive cardiac disease. Patients in whom cardiac tamponade or pericardial constriction are suspected should undergo a complete echocardiographic examination including careful Doppler analysis of transmitral flow and inflow through the hepatic vein or superior vena cava (SVC). Monitoring of both the electrocardiogram and the phase of respiration are an integral part of this examination. Patients with cardiac tamponade exhibit a > 25% reduction in E wave velocity during the first inspiratory cardiac cycle; they exhibit predominant systolic inflow through the hepatic vein or SVC (with a predominant X descent with little or no Y descent). In constrictive pericarditis the pattern of transmitral flow variation is comparable to that observed in cardiac tamponade, however, a prominent Y descent is often observed on hepatic vein or SVC Doppler study. Similar changes with respiration may be observed in mitral inflow in obese patients or in those with chronic obstructive pulmonary disease, however, in these conditions the nadir of E wave velocity is observed 2-3 cardiac cycles after the first inspiratory beat. Restrictive cardiomyopathy may produce a similar systemic venous flow pattern, but increased inspiratory flow reversals and lack of respiratory variation in transmitral flow velocity distinguish it from constrictive pericarditis.
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