Treating Inoperable Heart Disease: TMR (Transmyocardial Laser Revascularization)
TMR is a new procedure used to treat inoperable heart disease in people with persistent angina that isn't relieved by any other method.
Most people with coronary artery disease are treated with angioplasty and stenting or, coronary bypass surgery and medications to improve blood flow to the heart muscle. If these procedures do not eliminate the symptoms of chest pain (also called angina), other treatment options are available.
TMR, or transmyocardial laser revascularization, is a new treatment aimed at improving blood flow to areas of the heart that were not treated by angioplasty or surgery. A special carbon dioxide (CO2) laser is used to create small channels in the heart muscle, improving blood flow to the heart muscle.
How Does TMR Work?
TMR is a surgical procedure. It is performed through a small incision in either the left side or the middle of the chest. Frequently, it is performed along with coronary bypass surgery, occasionally alone.
Once the incision is made, the surgeon exposes the heart muscle. A laser hand piece is then positioned on the area of the heart to be treated. A special high-energy, computerized CO2 laser is used to create between 20 to 40 one-millimeter-wide channels (about the width of the head of a pin) in the left ventricle (left lower pumping chamber) of the heart. The doctor determines how many channels to create during the procedure. The outer areas of the channels close, but the inside of the channels remain open inside the heart to improve blood flow.
The CO2 Heart Laser uses a computer to direct laser beams to the appropriate area of the heart in between heartbeats, when the ventricle is filled with blood and the heart is relatively still. This helps to prevent electrical disturbances (arrhythmias) in the heart.
Doctors aren't sure how TMR improves blood flow to the heart. Clinical evidence suggests blood flow is improved in two ways:
- The channels act as bloodlines. When the ventricle pumps or squeezes oxygen-rich blood out of the heart, it sends blood through the channels, restoring blood flow to the heart muscle.
- The procedure may promote angiogenesis, or the growth of new capillaries (small blood vessels) that help supply blood to the heart muscle.
TMR usually takes one to two hours. The procedure may last longer if it is combined with other heart procedures.
Who Is a Candidate For TMR?
TMR is a treatment option for individuals who:
- Have severe angina, which limits their daily activities or causes them to wake from pain at night, despite medications.
- Have pre-operative tests that show ischemia (decreased blood supply to the heart muscle).
- Have a history of previous bypass surgery or angioplasty, and no further intervention is available.
- Have been told by their doctor that there is nothing that can be further done to help their symptoms.
TMR has shown positive clinical benefits for patients who may require one or two bypass grafts, yet also have other areas of the heart that are not able to be bypassed with direct bypass-surgery. This is often seen in patients with diabetes. The surgeon will bypass the targeted blockages and use the CO2 Heart Laser on the heart muscle with diffuse disease to achieve more complete blood flow to the heart.
TMR is not suitable for patients whose:
- Heart muscle is severely damaged due to heart attacks; the heart muscle is dead or scarred rather than affected by inadequate blood supply (ischemic).
- Heart muscle has no areas of ischemia (inadequate blood supply).