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Weight-based rt-PA thrombolysis protocol for acute native arterial and bypass graft occlusions
Aravind Arepally1, Lawrence V Hofmann, Hyun S Kim
1Russell H. Morgan Department of Radiology and Radiological Science, Division of Cardiovascular and Interventional Radiology, Johns Hopkins Medical Institutes, Baltimore, Maryland, USA. aarepall@rad.jhu.edu
Purpose:
To determine technical success and complications with weight-adjusted dosing of recombinant tissue plasminogen activator (rt-PA) for arterial and bypass graft occlusions.
Materials And Methods:
During an 8-month period, prospective data were collected on patients undergoing catheter-directed thrombolysis. Retrospective review of all medical charts and blood bank data were performed for confirmation. All patients underwent a standard weight-adjusted protocol for catheter-directed thrombolysis. Thrombolytic therapy with rt-PA (0.2 mg/mL) was defined as low-dose when 0.02 mg/kg/h rt-PA was used and high-dose when 0.04 mg/kg/h of rt-PA was used. Low-dose heparin therapy was used. Total infusion time, total dose, and hourly rate of dose were calculated. Technical success, defined as complete removal of all clot without surgical intervention, complications, and frequency of transfusions were tabulated.
Results:
A total of 35 patients underwent catheter-directed thrombolysis with rt-PA, including a total of 21 bypass grafts (60%) and 14 native arteries (40%). Mean age was 57 years (+/- 22.5; range, 3 mo to 83 y). Average rate of heparin infusion was 472.8 U/h (+/- 227). Success rates for graft thrombolysis were 90% (18 of 21). Success rates for native vessels were 79% (11 of 14). In patients who underwent only a low-dose protocol, the transfusion rate was 15% and major complications were 10%. In patients with a combined low-dose/high-dose administration, the transfusion rate was 46% and major complications were 13%. Overall success rate and major complication rates were 86% (30 of 35) and 11% (four of 35), respectively. Frequency of transfusions was 37% (13 of 35; mean, 2.8 U).
Conclusion:
Although weight-adjusted dosing for rt-PA provides a high efficacy of relieving ischemia, the rate of complications, especially bleeding, seems excessive in comparison to historical experience with urokinase. Administration of short-term high doses of rt-PA did not appear to have any beneficial effect. Further investigation with lower dosing and concentration should be considered.