PULMONARY-ARTERY DIASTOLIC-OCCLUSION PRESSURE-GRADIENT IS INCREASED IN ACUTE PULMONARY-EMBOLISM

Objective: To assess the pulmonary artery (PA) diastolic-occlusion (we dge) pressure gradient in patients with acute pulmonary embolism and t o evaluate this variable's diagnostic utility. Design: Retrospective, clinical review. Setting: Intensive care and cardiac catheterization u nits of a university medical center. Interventions: None. Patients: A series of 19 acute pulmonary embolism patients with concurrent right h eart catheterization. Control groups consisted of 19 age-, sex-, and h eart rate-matched critically ill controls who also underwent right hea rt catheterization, eight patients suspected of having pulmonary embol ism who had negative pulmonary angiography and concurrent right heart catheterization, and 255 patients with a primary diagnosis of coronary artery disease who underwent right heart catheterization at the time of left heart catheterization. Measurements and Main Results: Initial hemodynamics (systolic, diastolic, and mean systemic and pulmonary art erial pressures, occlusion pressure, PA diastolic-occlusion pressure g radient, cardiac output, systemic and pulmonary vascular resistances) were compared between cohorts. Other than differences in the PA diasto lic-occlusion pressure gradients, no significant differences were iden tified between cohorts. Pulmonary embolism patients were found to have increased PA diastolic-occlusion pressure gradients (10 +/- 5 vs. 3 /- 2 mm Hg for the critically ill controls [p < .0002], and 4 +/- 4 mm Hg for the coronary artery disease cohort [p < .0005]). However, no s ignificant difference in PA diastolic-occlusion pressure gradient valu es was identified when patients with proven pulmonary embolism were co mpared with patients in whom pulmonary embolism was clinically suspect ed yet not confirmed by angiograms (10 +/- 9 mm Hg; NS). For three of 19 pulmonary embolism patients, no occlusion pressure could be obtaine d due to an inability to wedge the balloon tip; 13 of 16 patients had PA diastolic-occlusion pressure gradients of greater than or equal to 8 mm Hg. In the pulmonary embolism cohort, PA diastolic-occlusion pres sure gradient correlated well with pulmonary vascular resistance (r(2) = .50; p < .05), but not with cardiac output or heart rate. Conclusio n: In the large number of patients with right heart catheters in whom the question of pulmonary embolism is raised, an increased PA diastoli c-occlusion pressure gradient (especially greater than or equal to 8 m m Hg) may provide a clue to the diagnosis of pulmonary embolism, but i s not specific for this diagnosis.