Home Grown Heart Bypass
In a discovery that may eliminate the need for heart bypass surgery, doctors have successfully inserted extra genes into the heart, enabling patients to grow new blood vessels.
Experts say this is the first time gene therapy has been used to correct an illness. The findings of the research were reported on Monday at a meeting of the American Heart Association in Dallas.
Several competing teams of doctors conducted experiments on people who had clogged vessels but were too sick to undergo ordinary bypass surgery or angioplasty. In conventional bypass surgery, a piece of blood vessel is grafted into place to create a detour around a blockage.
In this trial, the doctors injected a gene that controls production of VEG-F (vascular endothelial growth factor) which instructs the body to grow new blood vessels.
In all cases, the doctors reported clear evidence that the gene prompts the heart to sprout new blood vessels to nourish blood-starved muscle and relieve crippling chest pain.
Among those receiving injections of the VEG-F gene were 16 patients of Dr. Jeffrey Isner of St. Elizabeth's Medical Center in Boston, all of them heart attack victims who suffered excruciating chest pain at even the mildest exertion.
Dr. Isner and his team from Tufts University injected the gene right into the heart through a small incision in the chest. The operation lasted under an hour, and they were out of the hospital in days.
Some of Isner's patients were taking as many as 60 nitroglycerin tablets a week for their pain. Now all have improved substantially, and the average dose is 2 1-2 pills weekly. Of the 11 patients who have been followed up for at least three months, six are entirely free of pain.
A variety of tests, including nuclear scans, show improved blood flow to the patients' heart muscle, even though the blood vessels created by the treatment are too small to be seen.
At Cornell University in New York, Dr. Ronald Crystal and his team did a similar experiment using a cold virus to carry the VEGF gene into their 14 patients.
"We are trying to take damaged adult organs and return them to youth" said Dr. Crystal.
In a third experiment, Dr. Michael Mann of Harvard University tried using gene therapy along with bypass surgery, to see if that would make the bypass last longer.
They treated 16 patients with regular bypass grafts and 17 with genetically engineered grafts. The new arteries clogged up in 10 out of the 16 patients who got regular bypass and just 5 of the 17 who received the genetically engineered bypasses.
The doctors note that the procedure is still highly experimental and is probably several years away from routine use. It is also unclear whether this kind of genetic manipulation will work any better than a more direct medical approach, giving patients doses of the protein made by the gene.