What is Transmyocardial Laser Extravascular Angiogenesis?
Coronary artery disease (CAD) is a condition which affects a large number of people globally. This disease can lead to heart failure or reduced heart function because of poor blood flow or blockages in the heart’s blood vessels due to build up of fatty deposits or plaques known as atherosclerosis. Over the years, we’ve seen substantial improvements in both drug treatments and techniques to improve blood flow to the heart. Consequently, more people are now surviving heart attacks compared to the past. However, this also means that there are more people living with chronic or persistent chest pain (angina) and CAD.
Chronic refractory angina is a type of chest pain that doesn’t get better with the maximum care possible, whether that’s medical treatment or procedures to improve blood flow to the heart like coronary artery bypass surgery or a non-surgical procedure known as percutaneous coronary angioplasty (which uses a balloon to open blocked or narrow arteries).
For some patients with CAD and chronic angina, the standard treatments don’t bring relief. For these patients, more advanced treatments are being tested clinically. These include using a laser to improve blood flow through the heart muscle, electrical nerve stimulation, or inducing the development of new blood vessels through gene or cell therapy.
One such treatment, called transmyocardial laser extravascular angiogenesis (TMLR), has been shown to help improve symptoms, exercise capacity, quality of life, and decrease hospital readmissions for heart-related issues in patients with chronic refractory angina. TMLR, approved by the US Food and Drug Administration (FDA) in 1998, is used to treat moderate to severe angina in CAD that doesn’t respond to standard treatments. In this procedure, a laser is used directly on the surface of the heart to improve its blood supply. This technique has been in use in clinical settings since 1983, often in combination with coronary artery bypass surgery.
However, it’s important to note that all the clinical trials examining the effectiveness of TMLR have been closely studied. It was observed that many studies assessing improvements from TMLR didn’t follow a strict study design, where those surveying the participants are unaware of the treatment given. Additionally, many of these trials did not measure important outcomes like heart attack, abnormal heart rhythms, or heart failure, which are usually included in influential trials in cardiology. Current guidelines for managing refractory angina from cardiac organisations such as ACC/AHA do not recommend TMLR, either on its own or in combination with bypass surgery.
What Causes Transmyocardial Laser Extravascular Angiogenesis?
Transmyocardial laser extravascular angiogenesis (TMLR) is a treatment used for people suffering from severe and stubborn chest pain, known scientifically as refractory angina. This form of chest pain is a result of ischemic heart disease, which happens when blood supply to the heart is reduced. TMLR is especially employed for patients whose chest pain is caused by coronary artery disease (CAD), a condition where the vessels supplying blood to the heart get narrowed or blocked.
According to guidelines set by the American College of Cardiology and the American Heart Association in 2012, TMLR is recommended as a standalone treatment for patients with debilitating refractory angina that isn’t responding to medication and have no other available options. These guidelines also note that combining TMLR with another treatment known as Coronary Artery Bypass Grafting (CABG) doesn’t necessarily improve the survival rate in patients with refractory angina. However, this combination might help alleviate the chest pain for some selected patients.
Currently, TMLR is primarily used in clinical trials as a last resort treatment, especially since the development of newer non-invasive treatments like ranolazine, a medication used to treat chronic angina.
Risk Factors and Frequency for Transmyocardial Laser Extravascular Angiogenesis
In the United States, there are over 15.4 million cases of symptomatic CAD (coronary artery disease), with 400,000 new cases diagnosed each year. It’s also estimated that between 300,000 and 900,000 patients have refractory angina pectoris, a type of chest pain, with 25,000 to 100,000 new cases diagnosed annually.
According to a study, more than 20,000 procedures of a treatment called transmyocardial laser extravascular angiogenesis (TMLR) have been carried out in the United States, and over 50,000 procedures of TMLR have been performed worldwide as of 2014.
Signs and Symptoms of Transmyocardial Laser Extravascular Angiogenesis
Transmyocardial laser extravascular angiogenesis (TMLR) is a possible treatment for patients with refractory angina. These are patients who struggle with everyday activities like climbing stairs, walking, or house cleaning due to chest pain. Their quality of life is often poor, and they have a reduced life expectancy. Despite multiple attempts to quit smoking and trying various therapies and standard revascularizations, their chest pain persists. TMLR can be considered when other options have failed.
It’s noteworthy that there are no specific symptoms that show a patient with refractory angina needs TMLR. Typically, a general cardiac examination is performed. Patients usually display signs of stable angina, including periodic chest pain triggered by stress or physical exertion. Other symptoms might include:
- Fast heart rate
- High blood pressure
- Sweating
- Anxiety
In the course of an exam, abnormal heart sounds (S3 or S4) may be detected. Additionally, it’s important to obtain an EKG for any patient experiencing chest pain. The EKG may show temporary ST-segment depression, which suggests insufficient oxygen to the heart, but sometimes it might not show anything off.
Testing for Transmyocardial Laser Extravascular Angiogenesis
If you have stubborn chest pain, known as refractory angina, and all other treatment options have failed, your doctor might consider a procedure called transmyocardial laser extravascular angiogenesis (TMLR). However, it’s very important to weigh the risks and benefits of this procedure as it isn’t usually the go-to treatment for refractory angina.
Before having the procedure, you may have to undergo a basic heart assessment. This could include simple blood tests such as a complete blood count and a comprehensive metabolic panel. An ECG, which is a test that measures the electrical activity of your heart, may also be done.
Depending on your overall health and any other existing health conditions, you might also go through other tests such as an echocardiogram (a test that uses sound waves to create images of your heart), magnetic resonance imaging (a type of scan that uses strong magnetic fields and radio waves to produce detailed images of the inside of the body), or coronary angiography (a test that uses dye and special x-rays to show the insides of your coronary arteries). These tests will help your doctor to gauge the risk and benefits of the TMLR procedure for you, both during and after the operation.
Treatment Options for Transmyocardial Laser Extravascular Angiogenesis
Transmyocardial laser extravascular angiogenesis (TMLR) is a procedure where a laser beam is used to make tiny channels, or holes, in the heart. This technique is used for a certain group of heart patients. To get to the heart, doctors perform a type of surgery called an anterior thoracotomy at the patient’s left fifth intercostal space, where the ribs meet. This exposes the outer layer of the heart’s left ventricle and the sac around the heart. After determining the size of the area of the heart affected, the doctor uses a laser to make 20 to 40 tiny channels. These channels measure 1 millimeter in width and are spaced 1 centimeter apart. They are created from the bottom to the top, then to the side, and then on the surface of the outer layer of the heart. After that, a tube is placed in the chest, and the incision is closed. Most of the time, the breathing tube used during surgery is removed in the operating room. There are two FDA-approved laser systems that can be used in TMLR–a carbon dioxide (CO2) and a Holmium: Yttrium-Aluminum-Garnet, or Ho: YAG, laser system.
The CO2 laser works by generating an infrared light that can cut away heart tissue. This laser can only be used when the heart is beating, and the pulses of the laser have to be synchronised with the electrical activity of the heart to avoid triggering an irregular heartbeat. The Ho: YAG laser is different as it is guided manually by a fiber-optic bundle through the heart tissue as the laser is fired.
The common belief is that TMLR helps relieve pain relating to angina in the short and long term. This is because the heart has pain receptors and nerve fibres that transmit sensory information to the brain, located in the outer layer of the heart. So the theory is that TMLR cuts away these pain receptors and nerve fibres, blocking the pain signals from being sent. More than that, the removal of nerve fibres in the heart also reduces the production of a substance known as norepinephrine, which results in less heart muscle activity and lower oxygen demand, leading to relief for angina. Over the long term, TMLR inspires new blood vessel growth due to inflammation and vasculogenic mechanisms, providing a more comprehensive network of blood vessels in the areas where the laser channels were created. This also helps with the relief of angina symptoms. To substantiate this, a study has found that after TMLR, the heart muscle continuously releases VEGF, a substance that triggers the formation of new blood vessels.
Typically, this TMLR operation takes about two hours. The patient is then taken to the cardiac intensive care unit for recovery and usually spends around 4 to 7 days in the hospital following the procedure. Generally, it is recommended that patients continue taking all their heart medications on the same day after the operation.
What else can Transmyocardial Laser Extravascular Angiogenesis be?
Transmyocardial laser extravascular angiogenesis (TMLR) is a procedure carried out on patients suffering from persistent or “refractory” angina. However, there are other conditions that can mimic angina symptoms. So, before carrying out the procedure, doctors must rule out all other possible conditions.
The range of conditions that can look like angina is extensive. But when it comes to persistent angina, one should only consider the conditions which are also chronic and recurring. These include:
- Gastrointestinal issues like gastroesophageal reflux disease or a hiatal hernia
- Musculoskeletal conditions like muscle spasm or costochondritis
- Psychological disorders like anxiety or panic that results in chest pain
These conditions are often recurring and don’t respond to standard treatments for angina.
What to expect with Transmyocardial Laser Extravascular Angiogenesis
The outcome of a procedure known as transmyocardial laser extravascular angiogenesis (TMLR), which is a treatment for heart disease, can vary. Research indicates that, five years after undergoing the TMLR operation, roughly 64% of patients are still alive. Another study showed an even higher survival, with up to 80% of patients still alive ten years after the procedure.
However, it’s important to note that, in patients who live for many years after the procedure, chest pain linked to heart disease, also known as angina, can return within three years. Additionally, heart-related complications are most commonly found in those patients.
Possible Complications When Diagnosed with Transmyocardial Laser Extravascular Angiogenesis
The main complications you might have after a procedure called transmyocardial laser extravascular angiogenesis (TMLR) are heart-related. After having TMLR, you might experience a heart attack, abnormal heart rhythms, atrial fibrillation, poor ability of the left ventricle to pump blood, or heart failure. On rare occasions, other complications could include small clots travelling to the brain, stroke, pneumonia, severe infection in the bloodstream, and even death. These complications are more common among patients who have diabetes, chest pain due to heart disease, or have not been treated for a kind of heart disease called left anterior descending (LAD) coronary artery disease.
Possible Complications:
- Heart attack
- Abnormal heart rhythms
- Atrial fibrillation
- Poor heart-pumping ability
- Heart failure
- Small clots travelling to the brain
- Stroke
- Pneumonia
- Serious bloodstream infection
- Potential death
Preventing Transmyocardial Laser Extravascular Angiogenesis
It’s extremely important for patients to take their medication as instructed, participate in all necessary lab tests and imaging assessments, and attend regular check-ups, particularly with their general doctor, heart surgeon and heart specialist. These steps are crucial to their health and recovery.
Doctors should take the time to explain how the benefits of a particular treatment balance against any potential risks. Patients should be given honest information about the current research supporting the effectiveness of their treatment and why it has been recommended for their particular situation.
Doctors should also give the patient a general understanding of what they can expect in terms of their overall health outcome. This often involves discussing sensitive topics such as the patient’s preferences for life-sustaining treatments (code status) and instructions for their care if they become too ill to make their own decisions (advance directives).
