National clinical trials being conducted on inflatable tubular stent
Cardiologists at UW Medicine are participating in a national clinical trial to test a device designed to control bleeding if a vessel near the heart is inadvertently perforated during a catheter-based procedure.
Importantly, since patients in this life-threatening circumstance would be under sedation and unable to give informed consent to be involved, the researchers leading the trial have acquired a federal exception that allows them to enroll patients without consent.
The U.S. regulations that govern medical research include this exception so newly developed therapies can be tested for safety and effectiveness in patients who are in dire circumstances but cannot give informed consent to participate in a clinical trial, and time does not allow for a legally authorized patient representative to be reached.
“One example is new treatments for cardiac arrest. The affected person is typically unconscious and can’t communicate with first-responders who are studying whether a new drug or device works better than current standard care,” said Dr. Kathleen Kearney. She is an interventional cardiologist at the UW Medicine Heart Institute in Seattle and an investigator in this clinical trial.
Many heart procedures once conducted solely by surgeons are now performed by cardiologists using flexible tubes (catheters) and guidewires. These are inserted through tiny incisions and slowly pushed through a blood vessel until positioned to make the necessary repair. These procedures are referred to as percutaneous (meaning “through the skin”) coronary interventions (PCI). PCI give doctors a much less invasive way to unblock clogged arteries and insert devices to improve blood flow. They also usually mean much less recovery time for patients than would be the case with open surgery.
In a small fraction of PCI cases, as a guidewire or catheter is advanced into position, it inadvertently protrudes through a vessel wall, causing bleeding that must be controlled immediately to save the patient’s life. Current standard care, in these circumstances, involves inserting a balloon stent that totally seals off the leak, but it also halts coronary blood flow. Depending on the patient’s condition, the original procedure may be aborted or delayed until the leak is repaired, or the patient may be transferred to surgery to repair the leak and address the vessel blockage with a bypass procedure instead.
This clinical trial is testing a new device: an inflatable, ring-shaped stent designed to control bleeding while also permitting blood to flow normally through the vessel. Up to 15 U.S. hospitals will participate in the study and up to 30 patients will be enrolled.
“These perforated vessels are a known complication that we try to prepare for,” Kearney said. “You have to move exceptionally quickly in this moment of crisis. The thought with this test device is to apply pressure to the bleeding and supply blood flow at the same time. It should give us a chance to stop and reevaluate the situation.”
A patient whose vessel is perforated and whose alternative, in that moment, is surgery would be a candidate for trial enrollment, Kearney said, adding that the ring balloon would be advanced into place using the guidewire already in the vessel.
Patients enrolled in the study will be notified after the procedure when they are awake and alert. At that point, they can opt out of the study and decline future follow-ups associated with the clinical trial.
