What Is a Heart Attack?

A  heart   attack  [or Myocardial Infarction (MI)] occurs when the supply of blood and oxygen to an area of  heart  muscle is blocked, usually by a clot in a coronary artery. Often, this blockage leads to arrhythmias (irregular heartbeat or rhythm) that cause a severe decrease in the pumping function of the heart and may bring about sudden death. If the blockage is not treated within a few hours, the affected heart muscle will die and be replaced by scar tissue.

A  heart   attack  is a life-threatening event. Everyone should know the warning signs of a  heart   attack  and how to get emergency help. Many people suffer permanent damage to their hearts or die because they do not get help immediately.

If care is sought soon enough, blood flow in the blocked artery can be restored in time to prevent permanent damage to the heart. Yet, most people do not seek medical care for 2 hours or more after symptoms begin. Many people wait 12 hours or longer.

 Heart   Attack  Warning Signs

Cardiac arrest strikes immediately and without warning. Some  heart   attacks  are sudden and intense — but most  heart   attacks  start slowly, with mild pain or discomfort.

Often people affected aren’t sure what’s wrong and wait too long before getting help.

The following signs should not be ignored – they can mean a  heart   attack  is happening:

oChest discomfort. Most  heart   attacks  involve discomfort in the center of the chest that lasts more than a few minutes, or that goes away and comes back. It can feel like uncomfortable pressure, squeezing, fullness or pain.

oDiscomfort in other areas of the upper body. Symptoms can include pain or discomfort in one or both arms, the back, neck, jaw or stomach.

oShortness of breath. May occur with or without chest discomfort.

oOther signs: These may include breaking out in a cold sweat, nausea or lightheadedness.

As with men, women’s most common  heart   attack  symptom is chest pain or discomfort. But women are somewhat more likely than men to experience some of the other common symptoms, particularly shortness of breath, nausea/vomiting, and back or jaw pain.

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.

What causes a  heart   attack ?

Atherosclerosis

Atherosclerosis is a gradual process in which plaques (collections) of cholesterol are deposited in the walls of arteries. Cholesterol plaques cause hardening of the arterial walls and narrowing of the inner channel (lumen) of the artery. Arteries that are narrowed by atherosclerosis cannot deliver enough blood to maintain normal function of the parts of the body they supply. For example, atherosclerosis of the arteries in the legs causes reduced blood flow to the legs. Reduced blood flow to the legs can lead to pain in the legs while walking or exercising, leg ulcers, or a delay in the healing of wounds to the legs.

In many people, atherosclerosis can remain silent (causing no symptoms or health problems) for years or decades. Atherosclerosis can begin as early as the teenage years, but symptoms or health problems usually do not arise until later in adulthood when the arterial narrowing becomes severe. Coronary artery disease refers to the atherosclerosis that causes hardening and narrowing of the coronary arteries. Diseases caused by the reduced blood supply to the heart muscle from coronary atherosclerosis are called coronary heart diseases (CHD). Coronary  heart  diseases include  heart   attacks , sudden unexpected death, chest pain, abnormal  heart  rhythms, and heart failure due to weakening of the heart muscle.

Atherosclerosis and angina pectoris

Angina pectoris (also referred to as angina) is chest pain or pressure that occurs when the blood and oxygen supply to the heart muscle cannot keep up with the needs of the muscle. When coronary arteries are narrowed by more than 50 to 70 percent, the arteries cannot increase the supply of blood to the heart muscle during exercise or other periods of high demand for oxygen. An insufficient supply of oxygen to the heart muscle causes angina.

Angina that occurs with exercise or exertion is called exertional angina.

Exertional angina usually feels like a pressure, heaviness, squeezing, or aching across the chest. This pain may travel to the neck, jaw, arms, back, or even the teeth, and may be accompanied by shortness of breath, nausea, or a cold sweat. Exertional angina typically lasts from 1 to 15 minutes and is relieved by rest or by placing a nitroglycerin tablet under the tongue. Both resting and nitroglycerin decrease the heart muscle’s demand for oxygen, thus relieving angina. Exertional angina may be the first warning sign of advanced coronary artery disease.

Chest pains that just last a few seconds rarely are due to coronary artery disease.

Angina also can occur at rest. Angina at rest more commonly indicates that a coronary artery has narrowed to such a critical degree that the heart is not receiving enough oxygen even at rest.

While  heart   attacks  can occur at any time, most  heart   attacks  occur between 4:00 A.M. and 10:00 A.M. because of the higher blood levels of adrenaline released from the adrenal glands during the morning hours. Increased adrenaline, as previously discussed, may contribute to rupture of cholesterol plaques.

Approximately 50% of patients who develop  heart   attacks  have warning symptoms such as exertional angina or rest angina prior to their  heart   attacks .

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