By Diana Barnes Brown for Veins1
An experimental bypass procedure known as percutaneous in-situ coronary venous arterialization (PICVA) was used successfully on a 53-year-old German man, says a report released in late May of this year.
PICVA is unique among bypass techniques for two important reasons. First, the procedure is minimally invasive – a groundbreaking innovation for what used to be one of the most dangerous and invasive types of surgery in routine use. Second, the procedure actually makes use of a vein already existing in the area to bypass the blocked artery.
The procedure made headlines when it was reported in the May 29 issue of Circulation: Journal of the American Heart Association. Stephen N. Oesterle, M.D., director of invasive cardiology services at Massachusetts General Hospital and associate professor of medicine at Harvard Medical School in Boston, wrote the report. He noted that the technology used for the procedure "offers a realistic hope for truly minimally invasive bypass procedures in the future."
Bypass surgery is performed to prevent blood flow to the heart from being choked off, causing heart attack, tissue damage and frequently death. The problem for such patients is that often their bodies are already under so much stress from the blockage and contributing underlying conditions – such as obesity, cigarette smoking, and diabetes, for example – that undergoing major surgery represents a huge risk in its own right.
In traditional bypass surgery, the chest is opened, and a blood vessel from the chest (internal mammary artery) or calf (saphenous vein) is connected to the diseased heart artery on either side of the blockage, allowing blood flow to pass around the blockage (hence the name "bypass") and occur at a normal, healthy rate.
Several hundred thousand people undergo bypass surgery each year in the United States, and Dr. Osterle remarked that as many as 100,000 others may not be eligible for such surgery because their arteries are so clogged. Before the advent of PICVA, these patients were caught in a classic catch 22: too sick to have the surgery, but too sick to do without it for long.
When open bypass surgery was the only option, it was a gamble doctors and patients often had to take in order to prevent more severe damage to the body in the event of doing nothing. But with PICVA offering a minimally invasive alternative, the systemic trauma and many risks of traditional bypass surgery may soon be a thing of the past.
In PICVA, doctors use an ultrasound-guided catheter system to perform the procedure in a facility called a cardiac catheterization lab. The catheter is inserted into a large artery in the leg and then fed up through the vasculature to the aorta (one of the heart’s main pumping chambers), and into the affected coronary artery.
With the help of ultrasound guidance, a needle is pushed through the wall of the diseased artery and into an adjacent vein, and used to thread a fine, flexible wire into the place where the needle was, after which the needle is taken out. Doctors can then thread a small angioplasty balloon through the area on the wire, almost as one would sew a button onto a shirt, and use it to widen the passage that was created by the needle. After that, a small tube similar to a stent is inserted to keep blood flow going. Once the tube is in place, the vein can be closed off at the top, and blood can be successfully routed through it, restoring normal blood flow to the area.
Since arteries carry blood away from the heart and veins carry blood towards it, the procedure is much like routing traffic onto the opposite side of a two-way highway so that cars can get around an accident or other "clog" in the roadway. Also, blood that has begun to flow away from the heart is routed back towards it, feeding the muscle and restoring its function: in effect, the existing traffic is also forced to reverse its direction.
Dr. Osterle stated that more trials were needed before the procedure could be used widely. A 20-patient trial is currently underway, with clinical trials scheduled to begin in the United States later this year, and experts and patients alike are very optimistic about this promising new application of minimally invasive technology.
The German patient mentioned in the report underwent the procedure in 1999, and is doing well.
