Ventilation-perfusion scintigraphic evaluation of pulmonary clot burden after percutaneous thrombolysis of clotted hemodialysis access grafts

The objective of this study is to determine, by using rigorous methods, if pulmonary perfusion defects were detectable by ventilation-perfusion scinti graphy after percutaneous thrombolysis of clotted hemodialysis access graft s, Thirteen patients were studied. Four patients underwent pharmacomechanic al thrombolysis with urokinase and the remainder had mechanical thrombolysi s alone. Pre- and postthrombolysis scintigraphic studies were performed on all patients. Perfusion defects were described as vascular (well-defined bo rders confined to segmental boundaries) or nonvascular, Vascular defects we re graded by severity (0 to 3) and area (0 to 3) for each involved segment, Nonvascular defects were graded by severity (0 to 1)and area (0 to 1). Two experienced readers evaluated the scans blinded to each other's results an d all other clinical data, including thrombolysis outcomes. Twelve patients did not have any significant worsening of their perfusion defect scores po stthrombolysis, In only one patient did a study show a new nonvascular perf usion defect with a matching ventilation abnormality. The defect was believ ed to be caused by mucus plugging, The patient had no evidence of pulmonary embolism. Our study suggests emboli that resulted from the pharmacomechani cal or mechanical thrombolysis procedure were either small, underwent lysis before impacting the lung, or were below the limit of detection of ventila tion-perfusion scintigraphy, (C) 1999 by the National Kidney Foundation, In c.