Pulmonary Embolism Pioneer Recognized
Lazar J. Greenfield, MD, FACS of Ann Arbor, MI, was the recipient of the 16th Jacobson Innovation Award of the American College of Surgeons. The Jacobson Award, which honors living surgeons who have been innovators of a new development or technique in any field of surgery, was presented to Dr. Greenfield during a dinner that was held in conjunction with the ACS Board of Regents meeting.
An internationally recognized expert in vascular surgery, Dr. Greenfield was honored with the Jacobson Award in recognition of his seminal contributions in the technical development of the Greenfield filter, a device which changed the technology associated with the pulmonary embolic complications of deep venous thrombosis. The Greenfield vena cava filter is an implantable device inserted via a peripheral vein and was designed to prevent blood clots from reaching the lungs, a condition otherwise known as pulmonary embolism.
Since its introduction, the Greenfield filter has been implanted in more than 600,000 patients. The filter is invaluable to immobile patients since they are at highest risk of a blood clot due to the lack of movement. Before the invention of the Greenfield filter, surgeons would try to prevent pulmonary embolism by surgically closing, partitioning, or clipping the inferior vena cava, thereby stopping blood flow in the vein and forcing the blood to return to the heart through other veins.
The introduction of the Greenfield filter in 1973 provided the first effective method of trapping clots within blood vessels while simultaneously preserving blood flow within the IVC. Although blood-thinners have proved effective at preventing blood clots, many people, especially trauma patients, cannot take these agents because they pose an increased risk of internal bleeding and death.
The impetus for developing the filter came from a surgical emergency Dr. Greenfield encountered in 1968 when he treated a 23-year-old patient who sustained multiple fractures to both legs and the pelvis following a motorcycle accident, and developed a massive pulmonary embolism. Despite putting the patient on a heart-lung machine and applying the most aggressive surgical treatment of the time to remove numerous blood clots from the patient’s lungs, the patient did not survive.
Two years later he worked with Garman Kimmel, an oil-industry engineer and prolific inventor, to create an implantable filter for trapping blood clots before they can reach the lungs. The cone-shaped device consisted of six legs converging in the center that spanned roughly an inch across the vena cava. It had tiny hooks that secured it in place in the blood-vessel wall and corrugations in the legs that kept clots from slipping through. Clots that collected in the filter’s conical nose almost always dissolved as a result of the continuous flow of blood, which has natural clot-dissolving properties.
Currently, there are eight filter designs, including the Greenfield filter, approved for use by the FDA. For many years, the Greenfield filter has served as the benchmark by which newer filters were measured because it has the best long-term record. It has a recurrent pulmonary embolism rate of three percent, and studies have shown it to be more than 95 percent safe and effective.
Dr. Greenfield received his medical degree from Baylor University College of Medicine, in 1958 and completed his surgical training in general and thoracic surgery at the Johns Hopkins Hospital in Baltimore. During his training, Dr. Greenfield spent two years conducting research at the National Heart, Lung, and Blood Institute of the National Institutes of Health. In 1974 Dr. Greenfield was appointed the Stuart McGuire Professor and Chair at the Virginia Commonwealth University, a post he held for 13 years.
Following his work at VCU, Dr. Greenfield became the F.A. Coller Distinguished Professor of Surgery and chairman of the department of surgery at the University of Michigan, and is currently professor emeritus of surgery there. He has been a Fellow of the American College of Surgeons since 1968.