There are multiple indications for anticoagulation in the cardiac surgery intensive care unit including cardiac valve replacement, mechanical circulatory pumps (ECMO and ventricular assist devices), deep vein thrombosis prophylaxis, treatment of heparin-induced thrombocytopenia, and treatment of other thrombotic conditions including pulmonary embolism. Anticoagulant medications broadly fall into two categories: antiplatelet drugs and inhibitors of protein clotting factors. In this chapter we will review anticoagulant medications, therapeutic drug monitoring, common indications for anticoagulation, and the risks associated with anticoagulation after cardiac surgery.
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Anticoagulation management is a frequent issue in cardiac surgery critical care. There are a bevy of drugs available to today’s intensive care unit (ICU) practitioner allowing for maximal benefit and minimal risk when an anticoagulant is properly selected, dosed, and monitored. Available drugs work through different pathways, have different pharmacokinetic profiles, and have different routes of administration making them best suited for particular clinical scenarios. They also carry different levels of risk depending on a patient’s hepatic and renal function. For these reasons, ICU practitioners must be facile in managing the various anticoagulant medications that are available.
Anti-platelet drugs are used frequently in the cardiac surgery ICU, particularly in patients who have had coronary artery bypass graft (CABG) surgery, aortic replacement surgery, or bioprosthetic cardiac valve replacement. Almost all of these patients require aspirin and select patients receive dual anti-platelet therapy, typically with a thienopyridine drug.
Drugs that inhibit protein coagulation factors are also used in the cardiac surgery ICU for mechanical valve replacement, mechanical circulatory support devices or ECMO, prolonged atrial fibrillation in high-risk patients, heparin induced thrombocytopenia (HIT), pulmonary embolism, and certain bioprosthetic valves. Recently novel oral anticoagulant drugs have become available which will likely change future anticoagulation practices (eg: apixiban, dabigatran, and rivaroxaban).