The problem of thromboembolic disease

Cardiopulmonary thromboembolism detected by Tc-99m MH-1 antifibrin antibody

A patient with shortness of breath had a high probability lung scan for pulmonary embolism, but no obvious embolic source. Whole-body scintigraphy using Tc-99m labeled Fab' antifibrin monoclonal antibody showed large central pulmonary emboli as well as tracer uptake in the right atrium and aortic arch. No lower extremity clot was detected. This case shows significant differences in the appearance of pulmonary embolism as assessed by direct clot and ventilation-perfusion scintigraphy. It shows the importance of the heart as the origin of pulmonary emboli and the utility of direct thrombus visualization.

Prospective study of safety of lower extremity phlebography with nonionic contrast medium

BACKGROUND

Lower extremity deep venous thrombosis (DVT) following hig h osmolar ionic contrast phlebography has been reported to vary between 9% to 31%. The purpose of this study was to determine the incidence of minor and major adverse reactions and postphlebographic DVT when using nonionic contrast (iopamidol).

PATIENTS AND METHODS

One hundred fifty-seven patients with clinically suspected DVT were studied prospectively. One hundred eleven patients had prephlebography duplex ultrasound, and 102 patients were examined in the vascular laboratory for delayed side effects 1 week after phlebography. The presence of phlebography induced DVT was assessed using color duplex ultrasound. The mean amount of contrast used 102 ml.

RESULTS

Minor adverse reasons, including nausea, local pain, and dizziness, occurred in 11 (7%) of 157 patients; however, no major complications or postphlebographic DVT was found in the 102 patients who underwent postphlebography duplex ultrasound. Phlebography and pre- and postphlebography duplex ultrasound showed no acute DVT in 70 patients. The maximum hypothetical true rate of major complications (ie, postphlebography DVT) that would result in no detectable events in a population of 102 patients with follow-up (for a probability of P <0.05) is 2.9.

CONCLUSION

lower extremity phlebography using nonionic contrast material is safe, with no incidence of postphlebography DVT in our series. Its utilization should be encouraged if duplex ultrasound is not available.

Specific uptake of radioiodinated fragment E1 by venous thrombi in pigs

Fragment E1, a product of plasmic digestion of cross-linked fibrin, binds specifically in vitro to polymerized fibrin but not to fibrinogen. Purified human Fragment E1 was radiolabeled with 125I or 131I by the Iodogen technique. The uptake of radioiodinated Fragment E1 in vitro into forming or preformed clots was demonstrated. Animal biodistribution studies of radioiodinated Fragment E1 showed its rapid removal from the circulation; radioactive catabolites did not reside long in any organ and were excreted in the urine. The uptake in vivo was evaluated in pigs with preexisting venous thrombi of various ages from 1 h up to 5 d at the time of intravenous systemic injection of the tracer. Radioiodinated fibrinogen was also injected into the same animals to compare the uptake of the two tracers. Thrombus-to-blood ratios for Fragment E1 averaged 43:1 (range 10-108) and 29:1 (range 8-107) in thrombi 1-6 h and 1-5 d old, respectively. In contrast, mean thrombus-to-blood ratios for fibrinogen were, in the same time intervals, 26:1 (range 17-41) and 2:1 (range 0.5-3.9), respectively. It is concluded that radioiodinated Fragment E1 is a specific marker of thrombi in vivo: its uptake by fresh thrombi is better than that of labeled fibrinogen and, in contrast to radioiodinated fibrinogen, this fragment is incorporated into old thrombi as well.