Pulmonary embolus after coronary artery bypass surgery: a review of the literature

Abstract

Pulmonary embolus (PE) after cardiac bypass surgery is an uncommon complication but carries with it high morbidity and mortality. The incidence of deep vein thrombosis (DVT) and PE after cardiac bypass varies depending on postoperative thromboprophylaxis, the presence of indwelling central venous catheters in the lower extremities, and early ambulation. The clinical diagnosis of DVT remains difficult and challenging. Pulmonary embolus is often the first occurring clinical event. The safety and effectiveness of preventative pharmacologic agents, such as subcutaneous unfractionated or fractionated heparin or oral coumadin, remain largely unknown. Heparin-induced thrombocytopenia, generally associated with a high incidence of DVT and PE, occurs in approximately 3.8% of patients who have undergone cardiac surgery and are placed postoperatively on high-dose intravenous unfractionated heparin. Sequential compression devices (SCD) have not been effective in reducing the incidence of DVT in an ambulating cardiac bypass patient when added to routine elastic graded compression stockings (GCS). Very large clinical trials are necessary to prove the effectiveness of pharmacologic or mechanical preventative measures in reducing the incidence of PE after cardiac surgery above the commonly used GCS, early ambulation, and aspirin. In a nonambulating, higher-risk cardiac bypass patient with slow recovery, a more aggressive prophylaxis regimen might be necessary for optimal prevention, although further data are needed to support this hypothesis.