Surgeons here cut holes in heart to ease angina
Laser pierces left ventricle to aid blood flowMarch 13th, 1997
For the past nine months, Spokane cardiac surgeons have been performing an investigational procedure in which they use a laser to pierce the hearts of patients to relieve a serious form of angina, or chest pain.
The surgeons, Samuel Selinger, Roberto Catteneo, and David Sandler, and cardiologist R. Dean Hill are working with the Heart Institute of Spokane on a study coordinated by Eclipse Surgical Technologies Inc., a Palo Alto, Calif., company that makes the laser.
Sacred Heart Medical Center has purchased one of the units, and Spokane is one of several sites nationwide involved in the study, says Selinger. Eclipse hopes to secure U.S. Food and Drug Administration approval to market the device, which costs hundreds of thousands of dollars, Selinger says.
The procedure is targeted at a very specific patient set: those who suffer from Class IV angina, which is chest pain or chest tightness experienced during or after minimal exertion, such as walking across a room, or even while resting. It is caused by a lack of blood supply to the heart muscle.
Though millions of people have heart disease, only a smallbut growing numbersuffer from Class IV angina.
For various reasons, many of these people arent eligible for coronary bypass or angioplasty, says Selinger. Often, they already have had bypass surgery, or their disease has progressed so far that the vessels of the heart either are blocked completely or have become too constricted for angioplasty to be successful.
The current procedure for those patients is to manage their angina by using medications. However, Selinger says that a large percentage of people with Class IV angina have experienced little improvement after using the medications. He says that many are at an extremely high risk of suffering a fatal heart attack.
This is a very unfortunate group, says Selinger.
The investigational procedure with the laser is called transmyocardial revascularization, or TMR. Essentially, the procedure entails using the laser to cut holes in the left ventricle of the heart, through which blood can flow into a network of blood vessels that exist within the layers of the heart muscle.
Since last May, Selinger, Catteneo, and Sandler have performed the TMR procedure on a total of 15 patients. The results are considered preliminary, but Selinger says that every patient in the study has improved from Class IV angina to at least Class II. With Class II angina, they experience chest pain only after moderate exercise, such as walking up a flight of stairs. Also, he adds that after TMR, the patients sometimes are able to get by with significantly smaller amounts of medication for angina than before.
For inclusion in the study, patients must be recommended to the Heart Institute by their cardiologists and must not be candidates for other revascularization procedures, such as a coronary bypass or angioplasty.
Some of the patients admitted to the study are randomly selected to take part in the TMR procedure, while others undergo the currently accepted treatment of managing the angina with medications, Selinger says. However, if a patient tries the conventional treatment and doesnt respond to it, he or she can cross over and undergo the TMR procedure, he says. More than half of the patients who have taken part in the TMR procedure have tried the standard treatment first and found it wanting.
There is no placebo group in this study, says Dr. Katherine Tuttle, director of research at the Heart Institute. Everyone is at a minimum getting the standard level of care.
Selinger says that the TMR procedure requires making a large incision in the lower left chest, just beneath the rib cage. The left lung then is moved out of the way, and the sack that surrounds the heart is cut open.
For the main part of the procedure, surgeons use a fiber-optic cord that has a hollow, plastic tip about a millimeter in diameter. The cord, through which the energy of the laser flows, is attached to the laser device. The plastic tip is held perpendicular to the surface of the heart, and the surgeon fires the laser by stepping on a foot pedal. Within seconds the plastic tip is pushed through the surface of the heart into the left ventricle, then is removed. Selinger says a second device, called an echo machine, confirms that the tip has made it into the ventricular cavity before its withdrawn.
Mark Puhlman, a Heart Institute researcher and clinical coordinator of the study, says the energy of the laser dissipates when it contacts the blood pool within the heart, which prevents the laser from going all the way through the heart.
Selinger says that during a procedure, between 30 and 40 holes are made in the left ventricle, which is the cavity of the heart that forces blood into the aorta and ultimately out to the rest of the body.
Once a hole has been made, the outside surface of the heart heals almost instantly, sealing off the exterior of the new channel so that blood isnt lost into the chest, Selinger says. The remainder of the channel beneath the outside surface of the heart stays open, allowing blood in the left ventricle to escape via the new channel and into a network of vessels, known as sinusoids, that exist within the layers of the heart muscle. It is believed that during the healing process after the procedure the sinusoids are encouraged to open up and feed the ventricular muscle mass, Puhlman says.
Following the procedure, patients are examined every three months to monitor their progress. Selinger says that a patients recovery from this procedure is different than after other coronary surgeries. He says that it can take as long as three months to see initial results following the TMR procedure because it take awhile for the network of vessels to open up.
We have people that had the procedure six to nine months ago that still are improving, Selinger says.
In the past, similar procedures have been tried. For instance, during the mid-1960s myocardial acupuncture was developed to connect the left ventricle to the sinusoids by puncturing the hearts muscle tissue with a needle. The holes made by that procedure resulted in the formation of scar tissue, which eventually sealed off the channels that were made.
In the early 1970s, a carbon dioxide laser was tried. That laser has had favorable results. Its believed that holes made by a laser remain open because less scar tissue is created, and instead a lining develops around the inside of the channel, Tuttle says.
Selinger says that a holmium laser is being used in the test here and is technically more advanced than the carbon dioxide laser and is believed to be safer and more effective. He says that the carbon dioxide laser doesnt go through fat very well, and with it the energy from the laser only can be delivered in a straight line through the air. With the holmium laser, the energy can be sent through a fiber-optic cord that twists and turns.
We believe that this type of laser gives us more flexibility for the future, Selinger says.
He says he believes that as more people undergo bypass surgery and survive heart disease for a longer period of time, there will be more sufferers of Class IV anginaand more use for this laser procedure.
Originally, Eclipse Surgical Technologies was allowed to include a total of 126 people in its nationwide study, half of whom were to receive the TMR procedure, while the other half received the standard treatment, says the Heart Institutes Puhlman. He says that 126 people already have been studied, and preliminary results have been submitted to the Food and Drug Administration, which has allowed the study to continue and has extended the number of patients to 175 while it reviews the data it has received.
It can take a substantial amount of time for the FDA to approve this type of device, Selinger says.