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Use of Stents in Angioplasty.

“ What is worrying about today’s scenario is that we are getting very young patients with Coronary Artery Disease (CAD). Previously a “young patient” with CAD meant someone in his forties. Today we see patients in their twenties and thirties.” says Dr K Latchumanadhas MD DM, Consultant, Institute of Cardio Vascular Diseases, Madras Medical Mission, Chennai. A drastic change in lifestyle without adequate exercise is a contributing factor. But it also begs the question whether Indians have a greater susceptibility to Coronary Artery Disease.

Ten years ago, a by pass surgery was an exclusive type of treatment performed only in a few hospitals in the country and the option was limited to only the very rich. Today, even though costs are high, surgery is performed in many super speciality hospitals and patients from middle and poor classes are able to benefit from it.

Interventional Cardiology, involving less invasive procedures, like an angioplasty have become commonplace. One interesting development has been the introduction of “ stents” during an angioplasty, to keep the artery from narrowing. Dr Latchumanadhas discusses the highlights of using such a device.

What is Coronary Artery Disease?

When the blood vessels pumping oxygen rich blood to the heart become occluded (clogged) with deposits called plaques, the flow of blood to the heart is impeded causing Coronary Heart Disease. As plaque gets deposited on the inner walls of the blood vessels the space for flow of blood narrows. Many factors including ageing are responsible for this.

When the occlusion of the lumen (inner space of the blood vessel) is 70%, the patient experiences chest pain on exertion. We call this pain angina.

Sometimes the fibrous layer on the plaque gets ruptures and cholesterol is exposed to the bloodstream. There are many factors that trigger such a rupture. The body’s defence mechanism treats this rupture as a wound and forms a clot in the area and blocks the flow of blood to the heart completely. This deprivation of blood supply to the heart leads to a heart attack.

In the treatment of coronary artery disease, “interventional” techniques are used increasingly, rather than surgery. Could you tell us about this mode of treatment?

Cardiologists in India deal with luminal occlusion ( blocks in the blood vessel) in two ways:

  • Coronary Artery Bypass Graft Surgery (CABG)
  • PTCA- Percutaneous Transluminal Coronary Angioplasty

A Bypass Surgery requires the opening of the chest, routing blood through a lung-heart machine, stopping and then restarting the heart, and grafting new vessels.

A large blood vessel, like the saphenous vein in the leg, is taken and grafted next to the blocked arteries so that the blood flows through the new graft, around the blockage. The patient has to be hospitalised for at least a week He may take upto two months to return to an active normal routine. It is an invasive technique and a fairly serious procedure.

Percutaneous Transluminal Coronary Angioplasty (PTCA), an interventional method, uses a fibre optic camera to guide a catheter with a balloon directly to the blocked vessel. The balloon is inflated at high pressure. This crushes the plaque, plastering it as a thin layer along the wall of the vessel. This clears the lumen permitting an increased flow of blood. This is called Balloon Angioplasty.

In the past few years we have been introducing stents during an angioplasty to widen narrowed arteries.

What exactly are stents?

Stents are tubes made of metal mesh . These are scrimped over the balloons and inserted into the vessel, while performing an angioplasty. When the balloon expands to crush the plaque, the stent is left in the vessel to keep the vessel from narrowing. The radial strength of the stent is high.

The stent remains in the blood vessel. Over time, it gets covered with tissue from the inner lining of the coronary artery. Anti-platelet drugs are given to stop a blood clot from forming in the newly opened artery. These drugs are taken until the stent is covered with lining tissue.

Interventional cardiologists used stents initially as a bail out for complications. Today, cardiologists opt to use stents to keep the arteries from narrowing again after a plasty.

Is it better to go for an angioplasty or bypass surgery?

It all depends on the patient and the type of problem.

If major vessels are involved, as in the case of a triple vessel occlusion or a left main block, we advise surgery. Other considerations like the age of the person and over all health also play a part. In India, surgery is still the preferred option. We do not advise plasty for small vessel blocks or diffusely diseased cases (where you cannot pinpoint a specific place as the site of block).

Looking at both procedures per se, a plasty is less invasive and requires minimal hospitalisation (a couple of days). It also inconveniences the patient less. A plasty is almost like the extension of an angiogram. It is performed under local anaesthesia. A plasty can be performed on high risk patients and also on those who have suffered heart attacks.

A plasty using stents is a procedure that is state of the art and is going to play a part in the treatment of heart disease in the future.

Is a plasty using stents less expensive?

Yes and No.

You will save a lot on hospitalisation costs as a plasty does not require you stay in the hospital for more than a couple of days.

If you need only one stent to be inserted you might still spend less than what you will on a surgery. Multiple stents might may cost more than a surgery. This is because currently most super speciality hospitals import stents. Locally manufactured stents are not used, as their efficiency has not been well documented

What are the complications that may follow the introduction of a stent after a plasty?

A plasty is a fairly safe procedure. There are two possible outcomes that may undermine its effectiveness, though. In some cases, within three to six months, at the place where the plasty was performed, the vessel may close again. This is called restenosis. This is not because of collection of plaque, but is usually because of:

A. Recoil of the vessel wall. Because of its elasticity, after the initial expansion, the vessel may close up again.

B. The catheter might inadvertently injure the blood vessel causing scar tissue to form, which will again block the normal flow of blood.

The use of stents can reduce the possibility of recoil. However, restenosis can result even after the insertion of the stent, due to clotting. But the risk of restenosis is only about 20%. And we must remember, this restenosis can happen even in a by pass surgery. After the surgery the grafted vessel can also close up.

Actually, in most cases, neither procedure can be seen as a cure. They serve as palliative procedures to help the patient resume normal activity. The preventive aspects, with diet and lifestyle changes, must be promoted vigorously.

Stents have been used only recently. Their long term effects have not been studied…

Stents have been used for the past 10 years in advanced countries. Studies of survival/quality of life in the five-year period following stenting are encouraging. Technology is also helping to improve the effectiveness of stents. Trials are on for drug coated stents. The stent is coated with anti coagulant drugs and this will help prevent clots.

Tests are on for genetically coated stents, which will prevent restenosis.

How have stents impacted on the treatment of coronary artery disease?

As I see it, stenting and other interventional procedures will eventually make the Cardio-Thoracic surgeon redundant.

Even now, in some hospitals, stenting is done for major vessel blocks as well as for small vessel occlusion. It is said that stenting is possible for the entire vascular tree.

Digital technology has improved the capacity of instruments required in these procdures, both in obtaining accurate diagnoses and better results in the interventional procedures.

Dr K.Latchumanadhas MD DM: Dr Latchumanadhas took his MD in General Medicine from the University of Kerala. After completing his DM in Cardiology, he has been with the Institute of Cardio Vascular Diseases, Madras Medical Mission. He is interested in both interventional and non interventional cardiology. He has published several papers in international and national magazines. He is also interested in computers and multimedia.

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