mechanical revascularization

Abstract 

Mechanical revascularization in the acute myocardial infarction by primary angioplasty has several advantages over thrombolytic therapy. The short-term patency rates of the infarct-related artery range from 95 to 99% and a normal flow is achieved in more than 90% of the cases. This prompt and effective reperfusion is probably responsible for the improved prognosis with primary angioplasty. The better outcome after primary angioplasty is observed both in low- and in high-risk patients, in all ages and in patients presenting late (>6 h) after the chest pain. Pooled analysis of randomized studies, show that primary angioplasty as compared to thrombolysis, has a lower incidence of death, stroke and reinfarction. Additional advantages of primary PTCA include the possibility of reperfusion in patients in whom lysis is contraindicated or less effective (e.g. patients in cardiogenic shock, or with prior coronary artery bypass surgery) and the ability to provide prognostic information helpful in the patient triage. Thus, primary PTCA results in better outcome than thrombolysis when performed in centers with success rates comparable to those achieved in the randomized trials. Further studies are still needed to assess its long-term efficacy. Several randomized trials are underway to assess the role of stents and the use of more potent antiplatelet drugs, as the GPIIb/IIIa receptor blockers, in adjunct to balloon angioplasty in the treatment of acute myocardial infarction.

primary angioplasty

 The term coronary angioplasty is used to describe a technique wherein a balloon is used to crush blockages in the blood vessels (coronary arteries) supplying the heart, thereby restoring good flow of blood. These procedures are invariably followed by insertion of a metal scaffolding called a stent which prevents recoil and reduces re-blockage at the ballooned site, which is called a stenting procedure.

Balloon angioplasties and stenting techniques have become a very routine day to day procedure performed in most tertiary care hospital across the country. PRIMARY angioplasty, however, is a term used to describe an angioplasty done as a life saving emergency procedure in a patient with an on-going heart attack. Heart attacks occur due to sudden total occlusion of a preexisting partial block, thereby completely cutting off the blood supply to a portion of a heart muscle. These 100% blockages need to be removed within 3-6 hours from the onset of heart attack; else the muscle of the heart gets damaged permanently. Doing angioplasty in a critical patient of heart attack is in itself challenging and doing so in the critical window period of this 3-6 hours further adds to the challenge.

The only other option available for the treatment of heart attack other than the primary angioplasty is use of specific intravenous medications called “thrombolytic agents”. These agents are thrombus (clot) busting medications, and when administered in patients, dissolve the clot in 60-65% of cases. The remaining 35-40% of cases either die due to failed thrombolysis (failure of drug to lyse the clot), or even if they survive the attack, go home with a very weak heart due to a large portion of the heart muscle being permanently damaged. These patients who do survive with weak hearts go on to live with either heart failure, valve leaks, ruptures in the portion of the heart or rhythm problems (electrical disturbances) & have a very morbid and unproductive life, with abundant economical, social and psychological burden. We have millions of such patients in our country with this morbidity, which ultimately is a large burden to the state. On the other hand, success rate of primary angioplasty is more than 95% when performed in experienced hands. This requires not only specialized training in interventional cardiology, more importantly a dedicated team of nurses, and cath lab technician who can react quickly to an emergency call. Dr Ganesh Kumar, chief of interventional cardiology, at Dr LH Hiranandani hospital is amongst few operators in the whole country who is geared up for these types of procedures; with his round the clock primary angioplasty team available 24 x 7.

thrombolytic therapy

Definition

Thrombolytic therapy is the use of drugs that dissolve blood clots.

Purpose

When a blood clot forms in a blood vessel, it may cut off or severely reduce blood flow to parts of the body that are served by that blood vessel. This can cause serious damage to those parts of the body. If the clot forms in an artery that supplies blood to the heart, for example, it can cause a heart attack. A clot that cuts off blood to the brain can cause a stroke. Thrombolytic therapy is used to dissolve blood clots that could cause serious, and possibly life-threatening, damage if they are not removed. Research suggests that when used to treat stroke, thrombolytic therapy can prevent or reverse paralysis and other problems that otherwise might result.

Thrombolytic therapy also is used to dissolve blood clots that form in tubes put into people's bodies for medical treatments, such as dialysis or chemotherapy.

Description

Thrombolytic therapy uses drugs called thrombolytic agents, such as alteplase (Activase), anistreplase (Eminase), streptokinase (Streptase, Kabikinase), urokinase (Abbokinase), and tissue plasminogen activator (TPA) to dissolve clots. These drugs are given as injections, only under a physician's supervision.

Recommended dosage

The physician supervising thrombolytic therapy decides on the proper dose for each patient. He or she will take into account the type of drug, the purpose for which it is being used, and in some cases, the patient's weight.

Precautions

For thrombolytic therapy to be effective in treating stroke or heart attack, prompt medical attention is very important. The drugs must be given within a few hours of the beginning of a stroke or heart attack. However, this treatment is not right for every patient who has a heart attack or a stroke. Only a qualified medical professional can decide whether a thrombolytic agent should be used. To increase the chance of survival and reduce the risk of serious, permanent damage, anyone who has signs of a heart attack or stroke should get immediate medical help.

Thrombolytic therapy may cause bleeding. Usually this is not serious, but severe bleeding does occur in some people. This is especially likely in older people. To lower the risk of serious bleeding, people who are given this drug should move around as little as possible and should not try to get up on their own unless told to do so by a health care professional. Following all the instructions of the health care providers in charge is very important.

Thrombolytic therapy may be more likely to cause serious bleeding in people who have certain medical conditions or have recently had certain medical procedures. Before being given a thrombolytic agent, anyone with any of these problems or conditions should tell the physician in charge about it:

• blood disease or current or past bleeding problems in any part of the body
• heart or blood vessel disease
• stroke (recent or in the past)
• high blood pressure
• brain tumor or other brain disease
• stomach ulcer or colitis
• severe liver disease
• active tuberculosis
• recent falls, injuries, or blows to the body or head
• recent injections into a blood vessel
• recent surgery, including dental surgery
• tubes recently placed in the body for any reason
• recent delivery of a baby

In addition, anyone who has had a recent streptococcal (strep) infection should tell the physician in charge. Some thrombolytic agents may not work properly in people who have just had a strep infection, so the physician may want to use a different drug.

People who take certain medicines may be at greater risk for severe bleeding when they are given a thrombolytic agent.

Women who are pregnant should tell the physician in charge before being given a thrombolytic agent. There is a slight chance that a woman who is given thrombolytic therapy during the first five months of pregnancy will have a miscarriage. However, streptokinase and urokinase have both been used without problems in pregnant women.

After being treated with thrombolytic therapy, women who are breastfeeding should check with their physicians before starting to breastfeed again.

Side effects

Anyone who has fever or who notices bleeding or oozing from their gums, from cuts, or from the site where the thrombolytic agent was injected should immediately tell their health care provider.

People who are given thrombolytic therapy should also be alert to the signs of bleeding inside the body and should check with a physician immediately if any of the following symptoms occur:

• blood in the urine
• blood or black, tarry stools
• constipation
• coughing up blood
• vomiting blood or material that looks like coffee grounds
• nosebleeds
• unexpected or unusually heavy vaginal bleeding
• dizziness
• sudden, severe, or constant headaches
• Pain or swelling in the abdomen or stomach
• back pain or backache
• severe or constant muscle pain or stiffness
• stiff, swollen, or painful joints

Other side effects of thrombolytic agents are possible. Anyone who has unusual symptoms during or after thrombolytic therapy should tell a health care professional.

Interactions

People who take certain medicines may be at greater risk for severe bleeding when they receive a thrombolytic agent. Anyone who is given a thrombolytic agent should tell the physician in charge about all other prescription or nonprescription (over-the-counter) medicines he or she is taking. Among the medicines that may increase the chance of bleeding are:

• aspirin and other medicines for pain and inflammation
• blood thinners (anticoagulants)
• antiseizure medicines, such as Depakote (divalproex) and Depakene (valproic acid)
• cephalosporins, such as cefamandole (Mandol), cefoperazone (Cefobid), and Cefotetan (Cefotan)

Also, anyone who has been treated with anistreplase or streptokinase within the past year should tell the physician in charge. These drugs may not work properly if they are given again, so the physician may want to use a different thrombolytic agent.

Key Terms

Arteries

Blood vessels that carry blood away from the heart to the cells, tissues, and organs of the body.

Blood clot

A hard mass that forms when blood gels.

Chemotherapy

Treatment of an illness with chemical agents. The term is usually used to describe the treatment of cancer with drugs.

Dialysis

A process used in people whose kidneys are not working well. By way of a filtering machine, dialysis separates waste and other useless materials from the blood -- a job the kidneys usually do.

Paralysis

Loss of the ability to move one or more parts of the body.

Stroke

A serious medical event in which blood flow to the brain is stopped. This may be because of a blood clot in an artery or because an artery has burst. Strokes may cause paralysis and changes in speech, memory, and behavior.