Overview

Atherosclerosis is a condition in which plaque starts depositing on the inner walls of arteries thereby restricting blood-flow. It causes a wide range of consequences and complications. Coronary Artery Bypass Grafting (CABG) and Balloon Angioplasty with stenting are the traditional treatment methods for the condition. In the last 3 decades, Laser Angioplasty is slowly emerging as an alternate procedure that is more effective. As the name implies, the procedure uses high-intensity laser beams in a focused manner, to vaporize the plaque deposits, thereby clearing the stenosis or blockage in the blood-vessel. In this article, we will learn more about this procedure.

Introduction to Angioplasty

Given the modern lifestyle, atherosclerosis is a common condition today, and is one of the risk factors for heart failure and heart attacks. Cholesterol and other materials found in blood start depositing over time on the inner walls of arteries. As the buildup increases, it causes stenosis or narrowing of arteries which restricts blood-flow. The deposits even harden with time, into what is called ‘plaque’.

Most heart attacks are caused when a plaque ruptures and discharges its lipid rich core which in turn initiate a process that terminates in the formation of a clot or thrombus. Inflammation is believed to play a role in the rupture of an unstable plaque.

Stable plaques may however cause a physical narrowing in the lumen of the coronary artery

Traditional treatment methods include:

• Coronary Artery Bypass Grafting (CABG): The site of the blockage is bypassed using a clean piece of artery or vein taken from another part of the body.
• Balloon Angioplasty with stenting: A balloon is inserted into the site of the blockage and inflated, so as to widen the lumen. A wire-mesh called stent is then inserted to prevent the re- narrowing of the lumen.

Both procedures have their own advantages and drawbacks, success-rates and risks. The cardiologist would decide, in consultation with the patient and family, which is the suitable procedure, on a case-to-case basis.

Since the late 1980s, experiments have been conducted across the world to use lasers. Lasers, being high-energy or high-intensity beams, can vaporize the plaque material and help break it up completely. Its adoption has been slow as more research was required to determine its success rates and identify risks. In recent years, the adoption has increased. This is helping fine-tune the techniques further and address the possible risks, effectively.

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Also Read: What Is Laser Angioplasty?

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What is Laser Angioplasty?

Laser stands for light amplified stimulated emission of radiation. It involves generating high-energy or high-intensity beams of light that can be used for various purposes. They find application in a wide-range of industry processes. In medicine, laser beams can be used to ablate or destroy abnormal tissue in any part of the body.

There are various ablation techniques used in various treatments today such as thermal (uses heat), RF (radio-frequency waves), electric (shocks given at site) and powerful drugs injected into the tissue.

Laser is also one such ablation technique. It’s widely preferred as it causes less of thermal damage from heat-based ablation techniques and less of trauma to surrounding tissue from the other techniques mentioned above. In fact, depending on the laser technology used, one can have ‘cold lasers’ which do not create any heat. There are various laser technologies and techniques used for angioplasty, the most common being Excimer Laser.

Excimer lasers use high-pressure, pulsed-gas laser techniques. These create intense ultraviolet (UV) light that has a high peak-power at several useful wavelengths, which makes it highly efficient. The source of the laser emission (lasing technique) is a fast electrical discharge and the lasing medium is a high-pressure mixture of a rare gas like Argon and a halogen gas. The procedure is called Excimer Coronary Laser Atherectomy (ECLA).

How is the procedure done?

The procedure will be done under general anaesthesia. A small incision is made in the patient’s groin. With the help of real-time X-ray images and contrast dyes, the interventionist will gently push a guidewire into the femoral artery and all the way to the location of blockage. Then, a catheter (tube) is pushed inside the guidewire and moved to the blockage. Then, the excimer laser module will be inserted into the catheter and moved to the blockage area. The laser is excited and its beams help burn away the plaque on the artery walls. Once all the plaque has been vaporized to the cardiologist’s satisfaction, the laser module, catheter and guidewire are all pulled out of the body through the incision in the groin which will be closed subsequently. The patient will be moved to a ward and hospitalized for 1-2 days. Once all vitals are stable, the patient will be discharged.

Success Rates

Various studies have been conducted since the late 80s when the procedure was first introduced. All these studies were focused on studying the efficacy or success rates of the procedure. The results are encouraging.

In one study, a 1·3 mm diameter laser catheter, comprising 20 numbers of concentric 100 μm quartz fibres stacked around a central lumen, was used to ablate plaque in 30 patients with coronary artery disease (CAD). The laser catheter was based on an excimer laser that delivered energy at a wavelength of 308 nm, and having a pulse-width of 60 ns. The success rate was 90%, that is, 27 out of 30 patients were free of these lesions. The percentage of stenosis (blockage) dropped from 85% to 41% after the laser ablation. In 10 patients, the blood-vessel diameter after laser angioplasty was regarded as good enough, while in the remaining 20 patients, balloon angioplasty was carried out subsequently.

In another study of 200 patients that had ECLA done on them, as many as 119 patients (55.4%) had a residual blockage after ECLA of 50% or less. Clinical success was achieved in 183 patients (91.5%) which means, these patients had a minimum of 20% increase in diameter of the blood-vessel post the procedure, along with no complications from the procedure.

Another study conducted on 440 patients who had a repeat blockage and underwent ECLA. 92% of the patients had a successful procedure (less than 50% blockage post procedure). Balloon angioplasty was done on 99% of the patients following the ECLA. In 91% of the cases, the residual stenosis was less than 30%.

There are various studies with similar and consistent findings which have helped popularize the procedure.

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Also Read: Non-Invasive imaging methods to treat Heart Blockages

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Risks

There are some risks to an ECLA or laser angioplasty. The risk level varies from patient to patient and depends on various parameters. The doctors will watch out for them and address them effectively.

Broadly speaking, the risks or complications are:

• Abrupt closure of the vessel, after the procedure
• Q-wave myocardial infarction: this refers to heart attacks which show a Q-wave on a 12-lead ECG done after the attack
• Non–Q-wave infarction: When there is no Q-wave but there may be other pertinent ECG changes, it is said to be a Non Q wave Infarction
• Cardiac tamponade: In this, the sac around the heart fills up with either blood or other fluids, exerting pressure on the heart
• Stent damage – in case of patients who developed stenosis (restenosis) in spite of having a stent
• Perforations – the blood-vessel develops small holes or perforations
• Need for a CABG or bypass to be done as a permanent solution
• In very rare cases, the procedure has been fatal.

But given the overall positive scenario, ECLA is being used in the below situations.

Applications or ECLA

ECLA has been used or is being used for all of the below heart conditions:

• Acute Coronary Syndromes and Myocardial Infarction
• Non-crossable/Non-dilatable Lesions (where Balloon Angioplasty has been a failure)
• Chronic Total Occlusions (the blockage is 100%)
• Under-expanded Stents
• In-stent Restenosis
• Saphenous Vein Grafts narrowing or occlusion
• Coronary Bifurcation Lesions

Kauvery Hospital is globally known for its multidisciplinary services at all its Centers of Excellence, and for its comprehensive, Avant-Grade technology, especially in diagnostics and remedial care in heart diseases, transplantation, vascular and neurosciences medicine. Located in the heart of Trichy (Tennur, Royal Road and Alexandria Road (Cantonment), Chennai, Hosur, Salem, Tirunelveli and Bengaluru, the hospital also renders adult and pediatric trauma care.

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