Similiacare.com, A Complete Homeopathy Portal

HEART ATTACK (MYOCARDIAL INFARCTION)

A heart attack (also known as a myocardial infarction) is the death of heart muscle from the sudden blockage of a coronary artery by a blood clot. Coronary arteries are blood vessels that supply the heart muscle with blood and oxygen. Blockage of a coronary artery deprives the heart muscle of blood and oxygen, causing injury to the heart muscle. Injury to the heart muscle causes chest pain and pressure. If blood flow is not restored within 20 to 40 minutes, irreversible death of the heart muscle will begin to occur. Muscle continues to die for six to eight hours at which time the heart attack usually is “complete.” The dead heart muscle is replaced by scar tissue.

CAUSES OF HEART ATTACK

With advancing age, cholesterol and calcium are deposited gradually in the walls of the coronary arteries. These deposits are called plaques. The process is known as atherosclerosis, or “hardening of the arteries.”

• A diet high in cholesterol combined with smoking and lack of exercise can accelerate this process.
• As these plaques grow, they begin to impede the flow of blood.
• The growing plaque is like a firm shell with a soft inner core containing cholesterol.
• As blood hits a plaque during each heartbeat, the plaque may crack open and expose the inner cholesterol.
• The cholesterol may cause a blood clot to begin to form.
• The plaque and the blood clot block the artery partially or completely. The more the artery is blocked, the greater the resulting damage to the heart.

Atherosclerotic coronary artery disease

This most common type of heart disease is associated with several risk factors. The greater the number of risk factors you have, the more likely you are to have atherosclerosis. The most common risk factors are as follows:

• Hereditary (runs in the family)
• High cholesterol in blood, especially high levels of “bad cholesterol” (LDL, low-density lipoprotein) and low levels of “good cholesterol” (HDL, high-density lipoprotein)
• Cigarette smoking or other tobacco use, including cigars and chewing tobacco
• Obesity or excess weight
• High blood pressure (hypertension)
• Diabetes
• Physical inactivity, lack of regular exercise (sedentary lifestyle)
• High-fat diet
• Emotional stress
• Type-A personality (hard-driving, perfectionist)

Nonatherosclerotic coronary artery disease

Coronary arteries can be blocked by conditions other than atherosclerosis. These include inflammatory diseases of the arteries, trauma such as a cut or stab wound to the heart, and diseases that cause thickening of the coronary arteries.

Coronary embolization may cause a heart attack. Coronary embolization refers to a clot from elsewhere in the body breaking off and traveling to the heart.

Other causes of heart attack are blood or oxygen supply problems or outside influences such as cocaine abuse and complications from bypass or catheterization.

Certain heart problems leading to heart attack may be present from birth.

SYMPTOMS

Although chest pain or pressure is the most common symptom of a heart attack, heart attack victims may experience a diversity of symptoms that include:

• Pain, fullness, and/or squeezing sensation of the chest

• Jaw pain, toothache, headache

• Shortness of breath

• Nausea, vomiting, and/or general epigastric (upper middle abdomen) discomfort

• Sweating

• Heartburn and/or indigestion

• Arm pain (more commonly the left arm, but may be either arm)

• Upper back pain

• General malaise (vague feeling of illness)

• No symptoms (Approximately one quarter of all heart attacks are silent, without chest pain or new symptoms. Silent heart attacks are especially common among patients with diabetes mellitus.)

Even though the symptoms of a heart attack at times can be vague and mild, it is important to remember that heart attacks producing no symptoms or only mild symptoms can be just as serious and life–threatening as heart attacks that cause severe chest pain. Too often patients attribute heart attack symptoms to “indigestion,” “fatigue,” or “stress,” and consequently delay seeking prompt medical attention. One cannot overemphasize the importance of seeking prompt medical attention in the presence of symptoms that suggest a heart attack. Early diagnosis and treatment saves lives, and delays in reaching medical assistance can be fatal. A delay in treatment can lead to permanently reduced function of the heart due to more extensive damage to the heart muscle. Death also may occur as a result of the sudden onset of arrhythmias such as ventricular fibrillation.

Chest pressure, discomfort, or a bandlike sensation around the chest with squeezing or heaviness is a common symptom of heart attack.

• About one fourth of people having a heart attack have no pain (”silent” heart attack).
• Silent heart attacks are more frequent in people with diabetes.

The following symptoms suggest a heart attack:

• Chest pain or pressure (heaviness)
• Jaw pain, or extension of pain into the arms or shoulder, especially the left arm
• Unexplained shortness of breath
• Unexplained sweating
• Heartburn or feeling of indigestion
• Nausea or vomiting
• Back pain or upper abdominal pain
• General lethargy or listlessness (malaise)

COMPLICATIONS

Heart failure

If a large amount of heart muscle dies, the ability of the heart to pump blood to the rest of the body is diminished, and this can result in heart failure. The body retains fluid, and organs, for example, the kidneys, begin to fail

Ventricular fibrillation

Injury to heart muscle also can lead to ventricular fibrillation. Ventricular fibrillation occurs when the normal, regular, electrical activation of heart muscle contraction is replaced by chaotic electrical activity that causes the heart to stop beating and pumping blood to the brain and other parts of the body. Permanent brain damage and death can occur unless the flow of blood to the brain is restored within five minutes.

Most of the deaths from heart attacks are caused by ventricular fibrillation of the heart that occurs before the victim of the heart attack can reach an emergency room. Those who reach the emergency room have an excellent prognosis; survival from a heart attack with modern treatment should exceed 90%. The 1% to 10% of heart attack victims who die later include those victims who suffer major damage to the heart muscle initially or who suffer additional damage at a later time.

Deaths from ventricular fibrillation can be avoided by cardiopulmonary resuscitation (CPR) started within five minutes of the onset of ventricular fibrillation. CPR requires breathing for the victim and applying external compression to the chest to squeeze the heart and force it to pump blood. When paramedics arrive, medications and/or an electrical shock (cardioversion) can be administered to convert ventricular fibrillation back to a normal heart rhythm and allow the heart to pump blood normally. Therefore, prompt CPR and a rapid response by paramedics can improve the chances of survival from a heart attack. In addition, many public venues now have defibrillators that provide the electrical shock needed to restore a normal heart rhythm even before the paramedics arrive. This greatly improves the chances of survival.

DIAGNOSIS

A heart attack is not a quick event that lasts a few minutes and is over.

• A heart attack is a process that continues over several hours.
• Every minute that passes before treatment is begun, your heart sustains more damage.
• You must seek medical attention as soon as you suspect you are having a heart attack.

If you arrive at the hospital in an ambulance, the staff will be ready for you.

• They will evaluate your condition rapidly by examining you and, if you can answer, asking you questions about your symptoms.
• They will obtain an electrocardiogram (ECG) right away to look for signs of heart attack.
• A quick diagnosis is essential for starting treatment as soon as possible.

If you are thought to be having a heart attack, you may undergo the following tests upon arrival and/or during the next few days of your hospital stay.

Blood tests: Routine blood tests include blood cell counts, chemistry and electrolytes, and coagulation (clotting) function.

• Cardiac enzymes: When heart muscle is damaged, certain muscle proteins are released into the bloodstream and can be measured. Elevations of the levels of certain of these proteins, known as cardiac enzymes, strongly suggest that a heart attack is in progress or has occurred recently. Repeated testing of blood samples for cardiac enzymes is helpful in making the diagnosis of a heart attack, especially when the ECG is not diagnostic.
• Other enzymes: Some other enzymes tested include AST (SGOT, aspartate transferase) and LDH (lactate dehydrogenase).
• The 2 most measured enzymes are creatine kinase (CK) and troponin.
  • Creatine kinase is released from the cardiac muscle cells as they die and as their membranes dissolve. The level of this enzyme takes a number of hours after the beginning of the heart attack to peak. It returns to normal by 24 hours after the beginning of the heart attack. A form of this enzyme called MB subform is quite specific in showing cardiac damage.
  • Troponin-I and troponin-T are very useful enzyme tests. The levels of these enzymes rise by 6-8 hours after the heart attack begins and remain elevated above normal for as long as a week. To some extent, the level of troponin can predict the likelihood of complications for a person with a heart attack. The levels may also helpful in deciding what treatments should be used.

Electrocardiogram: This test detects the electrical activity of the heart and records graphlike tracings of each heartbeat (waves).

• It is safe and painless, and it takes only a few minutes.
• An ECG is performed by taping electrodes on your arms, legs, and chest. The electrodes pick up the electrical impulses of your heart from different points of view in your chest.
• ECG abnormalities diagnostic of heart attack are sometimes seen early in a heart attack, but the ECG may be normal at first and need to be repeated.
• Sometimes existing ECG abnormalities may make the diagnosis difficult.

Chest x-ray: This is not always done, but it can show abnormalities in the size or shape of the heart and indicate if fluid is collecting in the lungs, a sign or poor circulation.

Echocardiogram (echo): This is an ultrasound examination of the heart. The ultrasound device uses sound waves to create a detailed “picture” of the heart, which are then transmitted to a video monitor.

• This is a safe, noninvasive, and very helpful test.
• Echo may show problems in the heart structure, such as abnormalities in the movements of the heart wall. A heart attack is a damaged heart wall.
• It can show abnormal enlargement or pouching of the heart wall (aneurysm).
• Echo may also visualize complications of heart attack including valve problems, rupture of the heart muscle, or accumulation of fluid in the cardiac sac (pericardial effusion).
• The most important information obtained from the echo is the ejection fraction. This is a measurement of the strength of heart muscle. This information may be used to help predict outcome and to decide on treatment.

Coronary angiography: This is the best test for identifying blockages in the coronary arteries.

• It often is performed for people with persistent pain and those who have not received “clot-busting” drugs to re-open their blocked artery.
• At some hospitals, people are taken directly into the catheterization, or cath, lab from the emergency department after initial evaluation.
• In the cath lab, a long, thin plastic tube (catheter) is put into the femoral artery (in the groin) or the brachial or radial artery (in the arm) and guided into the openings of the coronary arteries. Dye is injected into the arteries to make them stand out on x-ray. Pictures are recorded for later review.
• Coronary angiography is an invasive test with potentially serious complications, but when performed by an experienced doctor, the risk of complications is relatively small.
• An angiogram is the best test to determine which treatment is most appropriate: medication, angioplasty, stent placement, or bypass surgery.

A stress test may be performed before a person leaves the hospital, after the patient is stable and recovering from the heart attack and/or procedure.

• Exercise stress testing involves recording an ECG while the heart is stressed and again at rest.
  • The “stress” is usually exercise, namely, walking on a treadmill.
  • Speed and elevation are gradually increased while recording the ECG.
  • Certain changes in the ECG indicate possible coronary artery blockage.
  • The exercise stress test is about 60-70% accurate in predicting increased risk of future heart attacks.
  • If the stress test indicates fairly severe blockage, coronary angiography may be needed to confirm the diagnosis and determine the need for further treatment.
• Radionuclide stress testing is another type of stress testing.
  • It uses a special camera that sees blood flow after a tiny dose of a radioactive “dye” (isotope) is injected into the blood.
  • It measures the quantities of blood flow that reach the different parts of the heart muscle through the coronary arteries.
  • Like the exercise stress test, pictures are obtained with exercise on the treadmill and then with rest.
  • People who are unable to walk on the treadmill may be given medication to “stress” the heart muscle.
  • If a particular coronary artery is blocked partially or completely, the part of the heart supplied with blood by that artery would appear as a “cold spot” on the pictures because no radioactive isotope reaches that area.
  • This test is quite accurate in diagnosing coronary artery blockage. The small amount of radioactivity is not considered to be harmful.

TREATMENT

Medical treatment may be started immediately, before a definite diagnosis of a heart problem is made.

General treatment measures include the following:

• Oxygen through a tube in the nose or face mask
• Nitroglycerin under the tongue
• Pain medicines (morphine or meperidine)
• Aspirin: Those with allergy to aspirin may be given clopidogrel (Plavix).

Clot-dissolving medicines: The tissue plasminogen activators (tPAs) can actually dissolve clots.

• The earlier these drugs are given, the better the chance of dissolving the clot and opening the blocked artery, protecting the heart muscle from further injury.
• If more than 12 hours has passed since the onset of chest pain, these drugs are less helpful.
• Potential risks of this therapy include bleeding.
• The most serious risk is a stroke (bleeding into the brain).

Angioplasty: Emergency coronary angiography and coronary balloon angioplasty (percutaneous transluminal coronary angioplasty, or PTCA) are available in hospitals equipped with a full-service cardiac catheterization laboratory. This is the most direct method of removing blockage in a coronary artery.

• Coronary balloon angioplasty is an extension of coronary angiography.
• A long, thin tube (catheter) is inserted in an artery in the groin or arm.
• At the tip of the catheter is a tiny, elongated balloon, which is threaded over a hair-thin guidewire into the narrowed coronary artery.
• Once the balloon is positioned at the blockage in the coronary artery, it is inflated.
• The balloon pushes aside the plaque and clot that are blocking the artery, allowing blood to flow more freely.
• The balloon is then deflated and removed with the catheter.

Stenting: A stent is a small, metal springlike device that may be inserted into a coronary artery after balloon angioplasty. After the catheter and balloon are removed, the stent stays in place, holding the artery open. A stent is better than angioplasty alone at keeping the artery from narrowing again.

Atherectomy: Sometimes the plaques are too rigid, bulky, or calcified to be treated by balloon angioplasty. In these cases, the plaque often can be removed by cutting it out with a drill-like rotary blade or a laser or other tool.

Medications

If you are having a heart attack, you will almost certainly be given some or all of these medications while you are in the hospital. Some you will continue taking at home.

• Intravenous (IV) nitroglycerin has been shown to improve blood flow to the heart muscle by relaxing (dilating) the coronary arteries and increasing blood flow. It is usually given for 24-48 hours continuously.
• Heparin is a “blood thinner,” or anticoagulant, which may be given after a heart attack. Heparin does not remove an existing clot, but it reduces the tendency of blood to clot in the coronary arteries. Some newer forms of heparin have recently been introduced that can be given as a shot instead of through an IV line.
• Beta-blockers are medications that decrease the heart rate and blood pressure. This reduces the heart’s workload and thus the amount of oxygen it needs. Beta-blockers may help prevent heart irregularities/life threatening rhythm disorders and future heart attacks.
• Angiotensin-converting enzyme (ACE) inhibitors may prevent repeat heart attacks and other problems when started early during a heart attack. They are especially useful in people with diabetes and those with a weakened heart muscle congestive heart failure).

Surgery

• Sometimes cardiac catheterization reveals extensive coronary artery disease. In such cases, you will need to undergo coronary bypass surgery.
• Standard coronary artery bypass grafting (CABG) is performed if many coronary arteries are narrowed or blocked. This is especially recommended when the left main coronary artery shows significant blockage. This is “open heart surgery,” meaning that the chest wall is opened. When performing a bypass, heart surgeons use sections of the mammary artery from the chest, radial arteries from the arms, or veins from the legs to create detours around the blocked arteries. For this surgery, you will be connected to a bypass pump, which does the work of the heart during the operation. Although this sounds dangerous, this surgery is considered very safe and has a very low rate of complications.
• Off-pump bypass surgery: Sometimes the surgeon can perform open heart surgery without using a bypass pump. The heart continues to beat during surgery. This type of surgery has even fewer complications than the standard procedure but is not always feasible.
• Minimally invasive coronary bypass: If just the front or the right coronary artery needs bypass, the bypass may be performed via a small keyhole-type incision without a large incision in the chest. The internal mammary artery is used for the bypass.

Follow-up

If you have a heart attack, you will receive detailed instructions for your care after leaving the hospital. You should follow these instructions carefully. The following general guidelines apply to recovery from an uncomplicated heart attack.

You may return to work or prior activity levels after about 2 weeks, resume sexual activity in 7-10 days, drive a week after leaving the hospital, and continue commercial air travel after 2 weeks, if you are feeling fine and totally asymptomatic. Those with complicated heart attacks or who still have symptoms should wait at least 2-3 weeks after symptoms go away before driving.

After a heart attack, you will need close follow-up with your health care provider.

• Coronary heart disease is a chronic (ongoing, long-term), progressive condition.
• Changing your risk factors only slows its pace.
• Angioplasty or bypass surgery only alleviates the symptoms and is not a cure. The disease may recur and progress.

Your health care provider will watch you carefully for the following developments:

• Any new symptoms or signs of disease progression through clinical evaluation, physical examination, and periodic ECGs or stress tests
• Silent ischemia by periodic treadmill or radionuclide stress tests or stress echocardiography

He or she will also manage the following aspects of your treatment and recovery:

• Risk factor management by checking blood pressure and cholesterol levels periodically
• Adjustment of medicines and management of their side effects
• Prescription for an exercise program (cardiac rehabilitation)

What is new in heart attack?

Greater public awareness about heart attacks and changes in lifestyle have contributed to a dramatic reduction in the incidence of heart attacks during the last four decades. Improved anticoagulant drugs such as hirudin and hirulog, are being tested and may complement current therapies. The role of the “super aspirins” (Reopro and Integrilin) is currently being investigated as well. More effective versions of TPA are being developed. Increasingly, paramedics can do ECGs in the field, diagnose a heart attack, and take patients directly to hospitals that have the ability to do PTCA and stenting. This can save time and reduce damage to the heart. Recent data has shown that lowering blood LDL levels even further than previously suggested may further decrease the risk of heart attacks. Research also has shown that inflammation may play a role in the development of atherosclerosis, and this is an active area of current investigation. There also is early evidence that with genetic engineering it may be possible to develop a drug that can be administered to clear plaques from arteries (a “scavenger molecule”).