Alternative Strategies For Anticoagulation In Cardiac Surgery With And Without

A variety of approaches to perform anticoagulation in HIT patients who require cardiac surgery with and without CPB has been reported, including the use of danaparoid, the thrombin inhibitors lepirudin and bivalirudin, and the combination of UFH with short-acting antiplatelet agents, such as platelet glycoprotein (GP) IIb/IIIa antagonists or prostaglandins. Experience with a planned reexposure to UFH to permit CPB in patients with a previous history of HIT, but who no longer have detectable HIT antibodies at the time of subsequent UFH reexposure, will also be discussed.

A. Danaparoid Sodium

Danaparoid is a low molecular weight heparinoid, which achieves its anticoagulant effect predominately by inhibition of coagulation factor Xa. The plasma antifactor Xa activity half-life is approximately 20 h and somewhat dependent on renal function. No antidote is available. Monitoring of its anticoagulant effect is performed by measuring plasma anti-factor Xa activity. In the United States, danaparoid is not currently available. However, in several other jurisdictions, danaparoid is available and indeed approved for prophylaxis and treatment of HIT (see Chapter 13).

Danaparoid has been used in various protocols for CPB anticoagulation in HIT patients (Magnani, 1993; Magnani et al., 1997; Magnani and Gallus, 2006). However, due to its long plasma elimination half-life, lack of a reversal agent, and the fact that danaparoid cannot be monitored with current point-of-care tests such as the ACT, its use during cardiovascular surgery with CPB is problematic, including a high major bleeding rate (42%), as well as potential for CPB thrombosis due to inadequate dosing (Magnani and Gallus, 2006).

In contrast, in a controlled prospective trial comparing danaparoid (bolus of 40 U/kg) and UFH in non-HIT patients undergoing coronary artery bypass grafting (CABG) without use of CPB (so called off-pump coronary artery bypass [OPCAB] grafting surgery), danaparoid was effective and associated with bleeding rates comparable to that seen with UFH, with only a minor increase in transfusion requirements (Carrier et al., 2003). Anecdotal experience with danaparoid in the setting of OPCAB for a patient with acute HIT has also been reported (Warkentin et al., 2001).

In peripheral vascular surgery, danaparoid has also been used with a single intravenous (iv) bolus of 2250 U. The reported incidence of major bleeding complications was about 6% (Magnani and Gallus, 2006).

0 0

Post a comment