Heparin dose, transfusion rates, and intraoperative graft patency in minimally invasive direct coronary artery bypass

Many investigators have demonstrated the short-term and midterm efficacy of minimally invasive direct coronary artery bypass (MIDCAB). However, the influence of heparin dosing during MIDCAB on postoperative and immediate graft patency is less well defined. This report outlines our experience with MIDCAB employing a variety of heparinization protocols. The traditional MIDCAB approach was used in 152 patients who underwent single-vessel off-pump coronary artery bypass. Before the left internal mammary artery was divided, a 150-U/kg bolus of heparin sodium was given to 76 patients (group 1), and 300 U/kg was given to another 76 patients (group 2). Additional heparin was given during the procedures to maintain an activated clotting times of greater than 300 seconds for group 1 and greater than 400 seconds for group 2. On average, patients in group 1 required more boluses of heparin during treatment than patients in group 2. A larger standard deviation from the mean was observed for the activated clotting time in group 1 at any time during treatment than for patients in group 2. The number of revised grafts was smaller in group 2 (1/76, 1.3%) than in group 1 (4/76, 5.2%). All of these revisions revealed thrombus at the site of anastomosis. In addition, noncoronary thrombotic complications were seen in 5 patients in group 1, and none were seen in group 2. Coronary artery surgery without cardiopulmonary bypass does not trigger the systemic inflammatory response, but surgical tissue trauma remains a constant. The preserved hemostasis theoretically may lead to a procoagulant state. This study demonstrates that insufficient anticoagulation therapy can lead to intracoronary thrombosis following MIDCAB as well as increased noncoronary thrombotic complications.