Early anticoagulation after mechanical valve implantation, and related complications.

BACKGROUND AND AIM OF THE STUDY: Anticoagulation is started soon after mechanical valve replacement as the risk of thromboembolic complications is especially high during the first six months after surgery. At present there is no consensus on the optimal protocol to prevent early thrombogenic complications, without increasing the risk of postoperative hemorrhagic events. Herein is presented a comparative analysis of the various anticoagulation protocols utilized at the authors' institution. METHODS: Between July 2001 and October 2006, a total of 503 patients underwent mechanical valve implantation at the authors' institution. The patients were allocated to three comparable groups, depending on the anticoagulation regime administered. Group A patients (n = 221) received only oral anticoagulation from the first postoperative day; group B patients (n = 159) received oral anticoagulation plus low-molecular weight heparin; and group C patients (n = 123) received unfractionated heparin within 12 h of surgery in addition to oral anticoagulation. RESULTS: At 48 h after surgery the mean postoperative drainage was 514.1 +/- 202 ml, 783.4 +/- 369.7 ml, and 718.4 +/- 305.5 ml in groups A, B and C, respectively. Two patients in group A, 12 in group B and nine in group C required the reinsertion of additional intercostal/pericardial drains for collections (p = 0.002). Twelve patients had tamponade (seven in group B, five in group C; p = 0.002), and nine (five in group B, four in group C) required re-exploration for excessive drainage at >48 h after surgery (p = 0.01). There were three incidents of valve thrombosis within the first postoperative six months (one in each group). Two of these patients had a suboptimal International Normalized Ratio (INR), while the third patient had an INR >5 with congestive heart failure with hepatic failure. All three were successfully thrombolyzed and recovered after initial ventilatory and inotropic support. The incidence of thromboembolic stroke was low in all groups. CONCLUSION: Early oral anticoagulation alone provides optimum anticoagulation and is associated with minimum complications. Early supplementation with heparin increases the risk of hemorrhagic complications but without reducing the thromboembolic risk.

Reduced left internal mammary artery blood flow on normal sternal retraction.

The left internal mammary artery is the conduit of choice for bypassing the left anterior descending artery. A 72-year-old man underwent off-pump triple-vessel coronary artery bypass. The left internal mammary artery was harvested with brisk blood flow from the distal artery on completion of harvesting, but normal sternal retraction with a Medtronic OctoBase retractor led to cessation of flow. A vein graft was utilized for the left anterior descending artery, and the internal mammary artery was grafted to the first diagonal branch. Computed tomography-angiography on postoperative day 5 demonstrated no possible cause of the reduced flow on sternal retraction.