Researchers may have found a method that could offer a safer alternative to open-heart surgery for high-risk patients.
A team at the National Institutes of Health (NIH) and Emory School of Medicine, Atlanta, has successfully performed a coronary artery bypass without cutting the chest wall.
They employed a novel intervention to prevent the blockage of a vital coronary artery, which is a rare but often lethal complication following a heart valve replacement.
The results suggest that a less traumatic alternative to open-heart surgery could become widely available for those at risk of coronary artery obstruction.
First author of the study Christopher Bruce, an interventional cardiologist at WellSpan York Hospital and NIH’s National Heart, Lung and Blood Institute (NHLBI), as well as an adjunct assistant professor of cardiology at Emory School of Medicine, said: ‘Achieving this required some out-of-the-box thinking but I believe we developed a highly practical solution.’
The patient was a 67-year-old man whose aortic valve had previously been replaced with a bioprosthetic valve, but, due to calcium deposition, the valve now required replacement.
However, the patient’s unique anatomy placed the opening, or ostium, of his left coronary artery so close to the valve that its life-sustaining blood flow would likely become blocked during the standard valve replacement procedure.
Adam Greenbaum, a senior author of the study and a physician at Emory School of Medicine, said: ‘Our patient had an extensive history of prior interventions, vascular disease, and other confounders, which meant that open-heart surgery was completely off the table. Having a minimally invasive alternative in a case like this is paramount.’
Due to several anatomical quirks, the patient was also not a good candidate for existing minimally invasive solutions.
Fortunately, Greenbaum and Vasilis Babliaros at Emory had recently begun developing a solution just for this kind of scenario.
Greenbaum said: ‘We thought, ‘why don’t we just move the ostium of the coronary artery out of the danger zone?’
Bruce, and Robert Lederman, who leads the Laboratory of Cardiovascular Intervention at the NHLBI, joined the Emory physicians to help turn their concept into a viable medical procedure, having used it successfully in animal models.
The procedure, ventriculo-coronary transcatheter outward navigation and re-entry, or VECTOR, creates a new route for blood flow that is a safe distance away from the aortic valve. And rather than opening the chest to do it, the researchers use the body’s natural vascular circuitry to reach the heart, slipping catheters through vessels in the legs.
While this mode of access is not new, what the study authors do with their tools once they get there is.
With VECTOR, the researchers pass a wire through the aorta and into the at-risk coronary artery. From there, they steer the wire deep into one of the artery’s branches, breaching the vessel into the right ventricle, one of the heart’s four chambers. There, they operate a separate catheter to ensnare that wire and then pull the wire’s end out through the femoral vein. Now, a continuous line from the aorta to vein, this wire enables loading of more sophisticated tools into the target artery.
The next goal of VECTOR is to produce a new ostium for the coronary bypass. They create one hole in the aorta downstream from the valve, out of range of potential blockage. The researchers make a second opening by piercing through the coronary artery wall using a special catheter, which is braced by an expandable mesh tube, called a stent. They pass two loose ends through each hole and then, as in the previous phase, tie them together to create another bridge, this time tracing a safe path for the bypass.
Using this second wire, the team feeds a coronary bypass graft through the two new openings. Once deployed, the graft provides a new route for blood flow that is out of harm’s way.
Greenbaum and Babaliaros at Emory, joined by Bruce, put these steps into practice in their patient.
Six months after the procedure, the patient showed no signs of coronary artery obstruction, meaning VECTOR’s first outing in a human proved to be a success.
Further deployments in more patients are still necessary before VECTOR is used more widely, but the team is hopeful of continued success following this major step forward.
The authors suggest that the new technique may also have a place treating coronary diseases more broadly, in cases where other approaches, such as stents, fail to keep arteries open.
