HEALTHWATCH
To treat a heart attack
DR. SANJIV AGRAWAL
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What actually happens in the treatment of heart disease?
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Photo: The Hindu Photo Library
Increasing stress: The main cause for increase in heart atttacks.
THE incidence of coronary artery disease (CAD) is rising in India and other developing countries. Moreover the disease is attacking people at a younger age. This is primarily due to increased stress, which causes the release of adrenaline. Constant release of this hormone is harmful for the heart's blood vessels. Other factors like increased incidence of smoking, poor food habits, lack of exercise, high blood pressure and diabetes contribute to the deposition of fat, cholesterol and other blood products in the blood vessels of the heart. This is called atherosclerosis.
It results in the obstruction of blood flow to the heart resulting in chest pain or angina. Angina may occur initially on exertion and is relieved by rest. As the obstruction increases, pain occurs with even minimal exertion or even at rest (unstable angina). In some patients, the atheromatous plaque can rupture with thrombus formations. This results in total occlusion of the blood vessel and can lead to heart attack.
Treatment for CAD
There are three modes of treatment for a patient with CAD. First is medical management with drugs to reduce the heart's oxygen demand (beta blockers) or increase blood supply to the heart by dilating the blood vessels (nitrates), antiplatelets and statins. Second is balloon angioplasty and third is bypass surgery. These are complementary and judicial use of one or more may be required through the lifespan of a patient. Change in lifestyle and risk factor modification is necessary for all patients.
Balloon angioplasty is a natural extension of the coronary angiogram. It is performed under local anaesthesia in a cardiac catheterisation laboratory. A specially designed catheter is used to cannulate the coronary artery. Through this catheter, a fine guide wire is passed and negotiated across the block. This guide wire acts as a railroad.
On this guide wire, a balloon catheter of an appropriate size is positioned across the lesion. The balloon is then inflated and this will crack open the block and improve the blood supply to the heart.
Drawbacks
But plain balloon angioplasty had two major drawbacks. During the procedure, five per cent of the patients face a tear in the artery (dissection) or a total occlusion necessitating an emergency bypass surgery. With the use of stents, this problem is taken care of to a large extent. Less than 0.4 per cent of patients who undergo angioplasty and stent face complications during the procedure.
The second problem was that of recurrence or restenosis. But with the use of stents this has come down significantly. The stent is like a scaffold that keeps the blood vessel open. It is made of stainless steel and other alloys like cobalt chromium and is inert with no reaction or rejection in the body. Once deployed properly, the stent will not move inside the body and in six to eight weeks, is covered with the natural lining of the blood vessel. In an effort to further reduce the chance of recurrence, stents are being coated with medication that can reduce restenosis.
Novel method
Angiogenesis is a novel mode of treatment. The growth of new blood vessels is promoted by directly injecting a stimulating factor (vascular endothelial growth factor) into the coronary artery. This is still in an experimental stage.
CAD can be present as silent ischaemia, stable angina and unstable angina. However the worst is acute myocardial infarction (heart attack). Atherosclerosis is a chronic process where cholesterol, fat and other elements from blood gradually block the coronary arteries. However during a heart attack, the plaque will rupture leading to formation of a clot resulting in sudden total occlusion of the blood vessel.
Three major problems
Patients with heart attack face three major problems: death before hospitalisation; death during hospitalisation and long-term survival.
Public awareness will help in early diagnosis. Well-equipped ambulance and trained personnel will also help in starting treatment early. This will reduce pre-hospital deaths.
In the hospital, patients died due to irregular heart rhythm (arrhythmia) or heart failure (muscle damage). Defibrillators reduce the mortality due to ventricular tachycardia and fibrillation. With the availability of pace makers, deaths due to slow heart rate (complete heart block) were reduced.
The next major aim is to reduce the extent of muscle damage, and death due to heart failure and cardiogenic shock. A thrombolytic agent is given as soon as the heart attack is confirmed. This will help dissolve the clot and establish blood flow, thus reducing the damage. But, for maximum benefit, thrombolitic therapy should be given in the first six hours and is potent in only 60-70 per cent of the patients. In others, the effects of a heart attack may be more severe.
The next development was primary angioplasty. With technological advancement, improved expertise and newer and more effective medication, angioplasty is safe and effective during a heart attack. With the primary angioplasty, death during the heart attack has come down significantly.
Patients with a massive heart attack (extensive anterior myocardial infarction, inferior infarction with right ventricular infarction), patients with huge congestion and low blood pressure (haemodynamic instability), patients with failed thrombolysis with ongoing ischaemia and patients in whom thrombolytic therapy cannot be given benefit most from primary angioplasty.
Patients who survive a heart attack should undergo investigation to assess muscle damage and extent of blockage of blood vessels so that appropriate treatment can be given.
The writer is a Senior Consultant Interventional Cardiologist based in Chennai.
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