Diagnosis of constrictive pericarditis by two-dimensional echocardiography: studies in a new experimental model and in patients.

The purpose of this study was to determine the value of two-dimensional echocardiography in detecting constrictive pericarditis. Serial two-dimensional echocardiography was performed in eight closed chest conscious dogs with experimental constrictive pericarditis, using a new model that creates constrictive pericarditis by the introduction of a pericardial irritant mixture. Constrictive pericarditis was confirmed in these dogs by cardiac catheterization and pathologic examination. Four patients with constrictive pericarditis and three patients with restrictive cardiomyopathy (amyloidosis) were also studied. Analysis of short-axis two-dimensional echocardiograms was performed to determine the frame by frame change in left ventricular cavity areas throughout diastole. Curves of diastolic left ventricular cavity area change versus percent duration of diastole were constructed for each animal and human subject. Pericardial thickness was measured at various gain settings on two-dimensional and M-mode echocardiograms and at post-mortem examination. In dogs with constrictive pericarditis, the echocardiograms seriously overestimated and correlated poorly with pathologic measurements of pericardial thickness. In dogs after constrictive pericarditis developed, 69 +/- 11% (mean +/- SD) (range 50 to 84) of cavity area change occurred in the initial 30% of diastole compared with 35 +/- 7% (range 20 to 45) in control two-dimensional echocardiograms (p less than 0.001). Four patients with constrictive pericarditis showed similar accelerated cavity expansion in early diastole, but three patients with cardiac amyloidosis showed more variable left ventricular diastolic expansion rates. It is concluded that two-dimensional echocardiograms can demonstrate characteristic diastolic filling abnormalities in constrictive pericarditis, but cannot accurately measure pericardial thickness.