Intravascular ultrasound in patients with acute pulmonary embolism after treatment with intravenous urokinase and high-dose heparin.

OBJECTIVE

To compare the diagnostic value of intravascular ultrasound (IVUS) with angiography in patients with pulmonary embolism.

DESIGN

Open, prospective clinical study.

SETTING

Two university hospitals.

PATIENTS

Angiography and IVUS were used in 11 patients (5 men) (mean (SD) age 50 (18) years) with acute pulmonary embolism.

INTERVENTIONS

At a mean (SD) of 6 (4) hours after thrombolytic therapy with urokinase and full-dose heparin, all patients underwent pulmonary artery angiography. Then 3.5 F mechanical, 20 or 30 MHz IVUS catheters were advanced into the pulmonary circulation.

MAIN OUTCOME MEASURES

The pulmonary circulation was studied by both methods to detect the presence of thrombus, and a modified Miller score (assessing perfusion defects only and not velocity of flow) was used to quantify the angiographic images.

RESULTS

The modified Miller score was mean (SD) 7.4 (2.3) points. 168 pulmonary artery segments (diameter range 2-14 mm) were studied by angiography and IVUS. On angiography, seven segments showed complete obstruction and 49 partial obstruction; 112 were normal. Two distinct types of thrombus formation were found by IVUS. Type A thrombus only partly adhered to the wall but otherwise was mobile and type B predominantly adhered to the wall. IVUS confirmed all seven angiographically complete obstructions but missed three (6%) of the 49 partial occlusions. Forty (87%) of the remaining 46 segments had type A thrombus and six (13%) type B. IVUS indicated a thrombus in 38 (34%) of the 112 angiographically normal segments; 20 (53%) showed a type A pattern and 18 (47%) a type B pattern (P < 0.001).

CONCLUSION

IVUS was more sensitive than angiography in detecting thrombus but the clinical impact of this finding is not clear as yet.