In the days of door to door vacuum cleaner salesmen, a common sales technique was to astound the prospective customer by cleaning a huge pile of debris from the living room rug. All these decades later, sometimes it's still amazing to see what a well-designed tool can do to clean up a big problem.
"The first time I used the AngioVac venous drainage system, it really was amazing," Russell Ronson, MD, of UAB Cardiovascular and Thoracic Surgery at Brookwood said. "When you see how large some of the throbi and emboli we've removed are, it's remarkable."
Russell Ronson, MD
Venous thromboembolism is the third leading cause of cardiovascular mortality. The AngioVac system from AngioDynamics offers a new approach to treatment that could change that statistic. It is the first nonsurgical method for removing major soft, fresh thromboembolisms obstructing the large central veins and the right atrium. It is also used in serious cases of deep vein thrombosis in the legs.
"In the past, there usually wasn't a lot we could do beyond giving patients blood thinners and hoping the body would dissolve the clot, or give them medicines to dissolve it, but that came with a high risk of bleeding. Now, if there's a life-threatening situation or a large clot in one of the big veins of the body, we can remove it," Ronson said.
The AngioVac cannula's balloon-actuated, expandable funnel-shaped distal tip is designed to enhance venous drainage flow and prevent clogging to facilitate removal of material. The system includes the cannula and the extracorporeal circuit, which can be used in procedures requiring extracorporeal circulatory support for up to six hours.
"Ultrasound and CAT scans show us where the problem is. We perform the procedure in a surgical suite where the AngioVac system is set up at Brookwood Hospital. Patients are under general anesthesia and are given a blood thinner," Ronson said. "Two incisions are required, one for the AngioVac cannula and one for the return cannula. Depending on where the obstruction is, we can get access through any combination of the femoral or internal jugular vein as needed."
The system can be used in both percutaneous and open procedures. Radiopaque markers on the distal end of the cannula allow visualization under fluoroscopic imaging. The cannula is available with either a straight or a twenty-degree tip deflection, which aids in access to a wider variety of anatomical locations. AngioVac devices can be used with other manufacturer's off-the-shelf pump, filter, and reinfusion cannula.
An outflow line, centrifugal pump, filter and inflow line create an extracorporeal bypass circuit. The circuit reinfuses the filtered blood back into the body, which helps to minimize blood loss and to prevent hemodynamic instability. Once the cannulas are in place, the centrifugal pump is activated, creating a one-way flow that provides suction.
"I've been using the system for around eight months now. It's not something I use every day or in every case, but when a patient needs it, it can make quite a difference," Ronson said. "We do a lot of other cardiovascular and thoracic surgery, but it seems that venous thromboembolism cases are becoming more common.
"More people are getting venous filters, which can become clogged. More cancer patients are developing clots, and they are common in people whose mobility is limited by illness or who have to be in bed for extended periods. When clots develop in the lungs, it can impair breathing and in the legs the swelling from obstructions can be very painful."
The AngioVac system has also been used to clear clots in trauma patients that have developed vein obstructions as a secondary complication.
Generally, the device works best on fresh, soft clots rather than old, hard obstructions which have attached to the vein, so when patients present with symptoms that may need intervention, the sooner an evaluation can be scheduled, the better.
Each year in the United States, there are an estimated 900,000 to one million venous thromboembolism events. Almost 60 percent occur in hospitals or nursing homes, with a fatality rate in hospitalized patients of 12 percent which rises to 21 percent in the elderly.
"Now that an increasing number of patients are having this problem, it's great that we don't have to just give them medications and hope for the best. We can clear obstructions and clean out those veins." Ronson said.