Fatal Pulmonary Embolism

Pulmonary Embolism (PE) is defined as a blood clot in the pulmonary arteries. This is a complication of another disorder known as “deep venous thrombosis” (DVT). DVT is defined as the formation of a blood clot in the venous system – generally in the legs or in the pelvis.

Deaths from pulmonary embolism each year exceed the total numbers of deaths from AIDS, motor vehicle accidents, and breast cancer. Approximately 10% of patients with pulmonary embolism die within the first hour of presentation. Since treatment in this first hour is difficult, if not impossible, guidelines have been established to treat patients at high risk prophylactically ( i.e., before the clots actually develop in the venous system).

Risk factors for DVT/PE include obesity, advancing age, cancer, and restricted mobility, as well as immobilization, surgery, and trauma. Approximately 60% of major trauma patients will develop DVT. Between 40% and 70% of orthopedic patients undergoing total hip or knee replacements will develop deep venous thrombosis. In these groups of patients, the use of anticoagulants (blood thinners) or intermittent compression devices have been shown to significantly reduce the incidence of PE.

In patients who develop pulmonary embolism, prognosis is directly related to the size of the clot and the impact on the heart. These clots break loose from their location in the veins of the pelvis, travel to the right side of the heart, and lodge in the pulmonary artery. Since the right ventricle of the heart is normally a low pressure system, the increased workload caused by the clot may cause congestive heart failure. In patients with a large clot, significant increase in the workload of the heart may result in a fatal cardiac arrhythmia.

Patients presenting with DVT or PE are treated with anticoagulants such as heparin. An immediate initiation of these types of drugs halts the formation of new blood clot and stabilizes the position of existing clot. Treatment with heparin reduces the risk of death from 30% to less than 8%. Thus, the strategies for reducing morbidity and mortality rates from pulmonary embolism are: prevention, early recognition, and timely treatment.

© May 2006. James F. Lineback, MD, FCCP.  All Rights Reserved. Excerpt from monthly Newsletter.