A heart attack is an injury to the heart muscle caused by ...



Heart diseases

Heart attack is an injury to the heart muscle caused by a loss of blood supply. It usually occurs when a blood clot blocks the flow of blood through a coronary artery — a blood vessel that feeds blood / oxygen to a part of the heart muscle. Interrupted blood flow to your heart can damage or destroy a part of the heart muscle. It can also be fatal.

Warning signs and symptoms

■ Pressure, fullness or a squeezing pain in the center of your chest that lasts for more than a few minutes

Pain extending beyond your chest to your shoulder, arm, back, or even to your teeth and jaw

■ Increasing episodes of chest pain

■ Prolonged pain in the upper abdomen

■ Shortness of breath

■ Sweating

■ Fainting

■ Nausea and vomiting

A heart attack usually strikes suddenly. It can occur anytime — at work or play, while you're resting, or while you're in motion. Many people who experience a heart attack have warning signs and symptoms hours, days or weeks in advance. The earliest predictor of an attack may be recurrent chest pain (angina) that's triggered by exertion and relieved by rest. Angina is caused by temporary, insufficient blood flow to the heart. The medical term for insufficient blood flow to the heart is cardiac ischemia.

Causes

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|Reference: What is angina? |

|Angina is a pain that comes from the heart. It is common in people over the age of 50. A common type of angina is caused by narrowing in the |

|arteries of the heart, this causes a reduced blood supply to a part(s) of the heart muscle. The blood supply may be not be enough when he is |

|resting. However, the heart muscle needs more blood and oxygen when it works harder. For example, when the person walk fast or climb stairs, the |

|heart rate increases to deliver the extra blood. If the extra blood that your heart needs during exertion cannot get past the narrowed arteries, the|

|heart 'complains' with pain. |

|[pic] [pic] |

|The common symptom of angina is a pain, ache or discomfort which you feel across the front of the chest when you exert yourself. (For example, when |

|you walk up a hill.) You may also, or just, feel the pain in your arms, jaw, neck or stomach. An angina pain does not usually last long. It will |

|usually ease within 10 minutes when you rest, and often within 1-2 minutes if you take some GTN (Glyceryl Trinitrate) |

| |

|The pain may also be triggered by other causes of a faster heart rate. For example, when you have a vivid dream or an argument. Some people have |

|non-typical pains, for example, when bending or eating. If the symptoms are not typical then it is sometimes difficult to tell the difference |

|between angina and other causes of chest pain such as a pulled muscle in the chest, or heartburn. |

| |

|Animated tutorial on angina : |

Heart attack

One who has angina also has a higher risk of having a heart attack (myocardial infarction Myo refers to "muscle;" cardio refers to "heart;" infarct refers to "death of tissue from lack of oxygen.). Briefly, a heart attack usually occurs when there is a sudden total blockage of a coronary artery. This is caused by a blood clot which forms over a patch of atheroma, and blocks the blood supply to a segment of heart muscle.

If chest pain which lasts longer than 15 minutes, or is different or more severe than usual. It may be a heart attack and immediate hospital care is needed.

Like any muscle, the heart needs a steady supply of blood, or the tissue will be damaged and begin to die. Without blood, heart cells are injured, causing pain or pressure. If blood flow isn't restored, heart cells can die and scar tissue can form, replacing working heart tissue. If too large an area of the heart muscle is damaged, a heart attack can be fatal.

A heart attack occurs when one or more of the tiny arteries supplying your heart with oxygen-rich blood (coronary arteries) become blocked. Blockages are usually due to a blood clot that forms suddenly where a coronary artery has narrowed over the years from a buildup of cholesterol and other deposits. This buildup of cholesterol and other deposits — collectively known as plaques — in arteries throughout the body is called atherosclerosis. When the coronary arteries narrow due to atherosclerosis, the condition is known as coronary artery disease.

Coronary artery disease is a major underlying cause of heart attacks. Factors that increase the risk of narrowed coronary arteries — and, thus, a heart attack — include family history of heart disease, a high level of low-density lipoprotein (LDL) cholesterol (the "bad" cholesterol), high blood pressure, smoking, obesity and physical inactivity.

(Rarely, a heart attack can occur when a blood clot from inside a diseased heart breaks loose and lodges in a healthy or narrowed coronary artery. Another uncommon cause of a heart attack is a spasm of a coronary artery that shuts down blood flow to part of the heart muscle. Drugs such as cocaine can cause such a life-threatening spasm.)

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Risk factors

Certain factors, called coronary risk factors, increase the risk of a heart attack. These factors contribute to the unwanted buildup of deposits (atherosclerosis) that narrows arteries throughout your body, including arteries to your heart. Coronary risk factors include:

High blood pressure. Blood pressure is determined by the amount of blood your heart pumps and the amount of resistance to blood flow in your arteries. Over time, blood pressure greater than 115/75 millimeters of mercury (mm Hg) can damage arteries that feed your heart by accelerating atherosclerosis. High blood pressure can be an inherited problem. The risk of high blood pressure increases as you age. But the main culprits for most people are eating a diet too high in salt and being overweight.

High blood cholesterol levels. Cholesterol is a major part of the deposits that can narrow arteries throughout your body, including those that feed your heart. A high level of the wrong kind of cholesterol in your blood increases your risk of a heart attack. Low-density lipoprotein (LDL) cholesterol (the "bad" cholesterol) is most likely to narrow arteries. A high LDL level is undesirable and is a byproduct of a diet high in saturated fats and cholesterol. A high level of triglycerides, a type of blood fat related to your diet, also is undesirable. However, a high level of high-density lipoprotein (HDL) cholesterol (the "good" cholesterol), which helps the body clean up excess cholesterol, is desirable and lowers your risk of heart attack.

Cigarette smoke. Smoking and long-term exposure to secondhand smoke damage the interior walls of arteries — including arteries to the heart — allowing deposits of cholesterol to collect and hamper blood flow. Cigarette smoke also increases the risk of deadly blood clots forming and causing a heart attack.

Lack of physical activity. An inactive lifestyle contributes to high blood cholesterol levels and obesity. Conversely, people who get regular aerobic exercise have better cardiovascular fitness, which decreases their overall risk of heart attack. Exercise is also beneficial in lowering high blood pressure.

Obesity. Obesity involves having a high proportion of body fat. Obesity raises the risk of heart disease because it's associated with high blood cholesterol levels, high blood pressure and diabetes.

Diabetes. Diabetes is the inability of the body to produce or respond to insulin properly. Diabetes greatly increases the risk of a heart attack by speeding up atherosclerosis and negatively affecting blood cholesterol levels.

Stress. One may respond to stress in ways that can increase your risk of a heart attack. If you're under stress, you may overeat or smoke from nervous tension. Too much stress, as well as anger, can also raise your blood pressure.

Alcohol. Consumed in moderation, alcohol helps raise HDL levels — the "good" cholesterol — and can have a protective effect against heart attack. On the other hand, excessive drinking can raise your blood pressure and triglyceride levels, increasing your risk of heart attack.

Family history of heart attack.. Your family may have a genetic condition that raises unwanted blood cholesterol levels. High blood pressure also can run in families. In addition, families may contribute to coronary artery disease by practicing or promoting poor health habits such as smoking or eating high-fat diets.

|Reference: Screening and diagnosis |

|Electrocardiogram (ECG). This records the electrical activity of the heart. |

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|Blood tests. Certain heart enzymes slowly leak out into your blood if your heart has been damaged by a heart attack. |

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|Chest X-ray. An X-ray image of the chest allows your doctor to check the size and shape of your heart and its blood vessels. |

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|Nuclear scan. This test helps identify blood flow problems to the heart. Trace amounts of radioactive material, such as thallium, are injected into |

|the bloodstream. Special cameras can detect the radioactive material as it flows through your heart and lungs. Areas of blockage in arteries — |

|through which less of the radioactive material flows — appear as dark spots on the scan. |

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|Echocardiogram. This test uses sound waves to produce an image of the heart. An echocardiogram can help identify whether an area of the heart has |

|been damaged by a heart attack and isn’t pumping normally or at peak capacity. |

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|Coronary catheterization (angiogram). This test can show if the coronary arteries are narrowed or blocked. A liquid dye is injected into the |

|arteries of the heart through a long, thin tube (catheter) that’s fed through an artery, usually in the leg, to arteries in the heart. As the dye |

|fills the arteries, the arteries become visible on X-ray and videotape, revealing areas of blockage. Additionally, while the catheter is in |

|position, it can be used to treat the blockage. This procedure is called angioplasty. |

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|A stress test may be required in the days or weeks following a heart attack. Stress tests measure how the heart and blood vessels respond to |

|exertion. E.g. walk on a treadmill or pedal a stationary bike while attached to an ECG machine. |

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|Complications |

|At the very least, a heart attack can occur without recognized pain and discomfort. At the most, a heart attack can cause death. Complications are |

|often related to the damage sustained by your heart during a heart attack. This damage can lead to the following conditions: |

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|Abnormal heart rhythms (arrhythmias). If your heart muscle is damaged from a heart attack, electrical “short circuits” can develop resulting in |

|abnormal heart rhythms, some of which can be serious, even fatal. |

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|Congestive heart failure. The amount of damaged tissue in your heart may be so extensive that the remaining heart muscle can’t do an adequate job of|

|pumping blood out of your heart. This decreases blood flow to tissues and organs throughout your body, producing shortness of breath, fatigue, and |

|swelling in your ankles and feet. Congestive heart failure may be a temporary problem that remedies itself after your heart, which has been stunned |

|by a heart attack, recovers over a few days to weeks. However, it can also be a chronic condition resulting from extensive and permanent damage to |

|your heart following your heart attack. |

|Treatment |

|Automatic external defibrillator |

|In the initial minutes, a heart attack can also trigger ventricular fibrillation. This unstable heart rhythm produces an ineffective heartbeat, and |

|the heart quivers uselessly. Without immediate treatment, ventricular fibrillation leads to sudden death. The timely use of an automatic external |

|defibrillator (AED) that shocks the heart back into a normal rhythm can provide emergency treatment before a person suffering a heart attack reaches|

|the hospital. |

|Most ambulance teams carry portable defibrillators. |

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|Medications |

|With each passing minute after a heart attack, more tissue is deprived of oxygen and deteriorates or dies. The main way to prevent progressive |

|damage is to restore blood flow quickly. |

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|Initial treatment of a heart attack in the emergency room may also involve prescription medications, typically given through a vein in your arm |

|(intravenously), such as: |

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|Thrombolytics. These drugs, also called clot-busters, help dissolve a blood clot that's blocking a coronary artery and blood flow to your heart. |

|Asprins and other blood-thinning medications. These drugs, such as heparin or hirudin, like aspirins, make your blood less "sticky" and less likely |

|to form more dangerous clots. |

|Pain relievers. If your chest pain or associated pain is great, you may receive a pain reliever such as morphine to relieve your discomfort. |

|Nitroglycerine. This medication, used to treat chest pain (angina), temporarily opens narrowed blood vessels, improving blood flow to and from your |

|heart. |

|Beta blockers. These medications help relax your heart muscle, slow your heartbeat and decrease blood pressure, making your heart's job easier. |

|Cholesterol-lowering medications. Examples include statins. These drugs help lower levels of unwanted blood cholesterol and may be helpful if given |

|soon after a heart attack to improve survival. |

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|Surgical and other procedures |

|In addition to medications, you may undergo one of the following procedures to treat your heart attack: |

|Coronary angioplasty. Emergency angioplasty, a procedure available at large medical centers, opens blocked coronary arteries, letting blood flow |

|more freely to your heart. |

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|Coronary artery bypass surgery. In rare cases, doctors may perform emergency bypass surgery at the time of a heart attack. |

|Reference: Coronary artery bypass surgery |[pic] |

| | |

|A coronary artery bypass graft operation is a type of open heart surgery. The | |

|surgery is done to reroute, or "bypass", blood around a clogged artery that | |

|supplies blood to the heart. A piece from a long vein in the leg or a piece of | |

|artery from the arm or chest wall is used as a graft. The graft is attached below | |

|the area of obstruction. | |

|Percutaneous Coronary intervention (PCI) |PCI begins by accessing the circulatory system via an artery in the groin or wrist.|

|PCI refers to a procedure to change or widen blood vessels, |A tube or catheter is advanced towards the heart. A guide wire is then advanced |

|usually blood vessels narrowed or constricted by the build-up of|beyond an area of narrowing. A balloon is advanced over the wire and inflated, |

|atherosclerotic plaque. This technique does not require opening |opening the artery. A coronary stent (a cylindrical wire mesh) is then deployed and|

|the chest or the heart, but instead uses a catheter to enter the|embeds itself in the artery wall. The balloon, wire and catheter are removed and |

|heart via the circulatory system. |the puncture site is sealed. |

|[pic] | |

| |Advantages |

| |PCI can be performed under local anaesthesia. Recovery is shorter and less painful |

| |than surgery (and there are no scars). The procedure is quicker and less expensive |

| |than surgery. |

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| |[pic] |

|Implantable cardioverter defibrillator (ICD) |

|Almost everyone has seen a physician on television, paddles in hand, yelling “Clear!”, then applying those paddles to the chest of a patient to |

|shock him “back to life”. As dramatic as the scene may be, defibrillation, or shock, can be the only way to stop certain deadly heart arrhythmias |

|before they kill. |

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|For those who are at high risk of the deadliest forms of arrhythmias – ventricular tachycardia and ventricular fibrillation – an internal |

|“shocking” device may provide the best defense against sudden cardiac arrest. Such a device, known as an implantable cardioverter defibrillator |

|(ICD), is considered effective in fighting cardiac arrest over 90 percent of the time, an astounding success for a condition that few survived as |

|recently as 15 years ago. |

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|If the heart beats too quickly - ventricular tachycardia, the ventricles will not have enough time to fill with blood and will not effectively pump|

|blood to the rest of the body. Left unchecked, the rapid heartbeat could cause death. To intervene, the ICD issues a lifesaving jolt of electricity|

|to restore the heart’s normal rhythm and prevent sudden cardiac death. |

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|ICDs also can act as pacemakers when a heart beat that is too slow (bradycardia) is detected. |

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|Most ICDs keep a record of the heart's activity when an abnormal heart rhythm occurs. With this information, the electrophysiologist, a specialist |

|in arrhythmias, can study the heart's activity and ask about other symptoms that may have occurred. Sometimes the ICD can be programmed to “pace” |

|the heart to restore its natural rhythm and avoid the need for a shock from the ICD. Pacing signals from the ICD are not felt by the patient; shock|

|signals are, and have been described as a kick in the chest. |

The End

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