Transmyocardial Laser Revascularization (TMLR)

In this operation, a laser, used either through a catheter or directly through a surgical incision, is used to burn tiny holes in the heart muscle itself. It is hoped these channels will, over time, connect with some of the smaller blood vessels and form new circulation.

Is Transmyocardial Laser Revascularization Suitable For Every Patient?

Not every person with coronary artery disease is a candidate for TMLR. In many cases, bypass surgery and balloon angioplasty produce good short term and long term results. However, in an increasing number of persons, coronary artery disease has progressed to such an advanced and severe form that surgery is no longer possible. These patients typically acquire coronary artery disease at a younger age, are more likely to be diabetic with multiple risk factors, and are more likely to have already had numerous bypass and balloon procedures. In addition, candidates for TMLR must suffer from severe symptoms, like angina or chest pain, that interfere with their quality of life. Maximal medical therapy must have already failed, and any additional medications must be contraindicated. Also, TMLR treatment is not beneficial for heart failure.

How can Transmyocardial Laser Revascularization (TMLR) help you?

No one has yet determined how the laser treatment improves symptoms and the blood supply to the heart. It was initially thought that the holes created by the laser infuse the heart muscle with a new blood supply directly from the heart cavity (such a system exists in animals such as crocodiles or snakes). However, these channels do not stay open for long, and their role in long term blood supply is minimal, if any. Other possibilities include damage to the heart muscle and its nerve supply that eliminates the origin of chest pain. Also, a placebo effect has been postulated, meaning that patients mistakenly believe they should get better because a supposedly very useful treatment was performed. These reasons may explain the improvement of symptoms. Nevertheless, because the symptoms take weeks or sometimes months to improve, the above mechanisms are highly unlikely.

However, it is now believed, although not yet proven, that the laser energy stimulates the heart muscle to sprout new blood vessels that supply blood to deprived parts. This is called angiogenesis and can also be stimulated by certain body proteins.

How is TMLR performed?

TMLR is performed through an incision in the left side of the chest just underneath the left breast. The heart-lung machine is not required, and the operation is performed on a beating heart. Because the overwhelming majority of these patients have had previous coronary artery bypass operations, it is unsafe to perform this operation through the sternum, or breastbone. In addition, the back of the heart is more accessible from the left side of the chest without the need to apply too much tension to the heart, which could lower blood pressure during the operation.

Because it takes some time for a new blood supply to the heart muscle to develop after TMLR, the possibility of a reduction in blood supply as a result of

the stress of anesthesia and surgery is increased. Therefore, extra vigilance is needed after the procedure to deal with these problems before they become more serious. Aggressive preventative measures include noninvasive monitoring and mechanical and pharmacological support. In addition, all patients are sent to the intensive care unit after surgery for close monitoring.

The operation lasts between one and a half and two hours on an average. Patients can be disconnected from the respirator and their breathing tube removed either in the operating room or as soon as they wake up in the intensive care unit.

What kind of improvement could I expect after TMLR?

The major impact of TMLR has been in relief of angina, reduced need for hospital admissions, and an improvement in the quality of life. About three out of four patients have experienced these benefits. The need for hospital admission because of unstable angina was also substantially reduced. Even more encouraging, there has been no deterioration in heart function and no damage to the heart muscle resulting in heart failure symptoms.