Does rapid volume loading during transesophageal echocardiography differentiate constrictive pericarditis from restrictive cardiomyopathy?

Background: Respiratory variation of the pulmonary venous (PV) peak flow velocities can be used to distinguish constrictive pericarditis (constriction) from restrictive cardiomyopathy (restriction). Rapid volume expansion has been used successfully to enhance diastolic pressure equalization in occult constriction. The effect of volume on the respiratory variation in constriction has not been studied previously. This study assessed the utility of volume in enhancing the PV respiratory variation of constriction to further separate it from restriction. Methods: The study population consisted of 15 patients referred to the echocardiography laboratory for further evaluation of clinically suspected diastolic dysfunction. Pulsed-Doppler transesophageal echocardiography (TEE) of the left or right upper pulmonary vein and mitral inflow was performed with respiratory monitoring before and after infusion of 1 liter of normal saline over 5 to 10 minutes. The classification of patients as constriction (n = 8) or restriction (n = 7) was confirmed independently by cardiac catheterization or surgery. Peak velocities of the PV systolic and diastolic waves and the mitral inflow E were measured during inspiration and expiration. A mean of 3-6 respiratory cycles was obtained for each value before and after volume loading. The percent change from expiration to inspiration (FOE) was calculated using the formula %E = expiration - inspiration/expiration. Results: At baseline, patients with constrictive pericarditis can be separated reliably from those with restrictive cardiomyopathy based on a higher systolic/diastolic ratio and greater respiratory variation of their PV diastolic flow velocity. There were no complications in any patient due to volume expansion. Although the change from baseline to volume expansion was not statistically significant in either constriction or restriction, the %E of the PV diastolic wave became significantly higher in constriction than in restriction (P < 0.05). Conclusions: Rapid volume expansion is relatively safe during TEE and can be used for further separation of constrictive pericarditis from restrictive cardiomyopathy by significantly enhancing the respiratory variation of the PV diastolic flow velocity in constrictive pericarditis.