July 12, 2012

Minimally invasive therapy eases some pulmonary embolism

A pulmonary embolism (PE) is a blood clot that travels to the lungs and is one of those sneaky, and dangerous, conditions that can appear in perfectly healthy people, perhaps after a long flight or, as in the case of veteran NBC News reporter David Bloom, after sitting in a cramped military tank for several hours.

Bloom died in 2003 when a deep vein thrombosis in his leg traveled to his lungs.
Cancer patients, trauma patients and even women on birth control pills who are genetically predisposed to hyper coagulation are all at risk. About 600,000 people a year develop PE, marked by symptoms such as shortness of breath, chest pain, rapid heart rate and fainting, all of which can mimic a heart attack. Nearly half of those diagnosed with PE die because the blood clot obstructs the major blood vessels leading from the heart to the lungs.

Vanderbilt Heart and Vascular Institute now offers a minimally invasive, catheter-based approach to dissolving less critical obstructions called sub-massive pulmonary emboli. Using the EKOS catheter, interventional cardiologists are able to infuse a clot-dissolving drug known as tPA directly into the pulmonary embolus.

The EKOS catheter uses ultrasound during the drug infusion, which pulls apart the fibrin particles to allow the medicine to get into the center of the clot, accelerating dissolution.
For large PEs, two EKOS catheters can be placed into both the left and right pulmonary arteries via the femoral vein for ultrasound-assisted tPA infusion.

This approach is reserved for patients who are hemodynamically stable but have a dysfunctional and enlarged right ventricle. These patients have a higher risk for becoming acutely unstable, developing chronic pulmonary hypertension in the intermediate-to-long term, and mortality, said Pete Fong, M.D., assistant professor of Medicine.

Pete Fong, M.D.

“Typically, cardio-thoracic surgeons will be consulted to evaluate patients with large pulmonary emboli to determine if they are appropriate candidates for surgery,” Fong said. “If they are not, then interventional cardiologists will see if a catheter-based approach should be offered. We are able to care for these patients through a team approach unique to Vanderbilt Heart.”

In the past, patients with sub-massive PE were given heparin and Coumadin, which kept the clot from growing and new clots from forming, but did not remove them.

“The catheter-based approach improves the patient’s condition within minutes to hours of initiation and utilizes one-third of the thrombolytic therapy used in systemic administration, making it less likely to cause major bleeding. It is much less invasive than surgical thromboembolectomy, which requires a sternotomy,” Fong said.

Last year, Vanderbilt implemented a Level 1 Cardiac Emergency System, designed to deliver coordinated, expedited care for heart patients with complex and life-threatening problems, including ST elevation myocardial infarction, cardiogenic shock, acute pulmonary embolism and aortic dissection. VHVI has now treated three PE patients utilizing this protocol.