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Myocardial infarction

Dr Sudhir Bhatnagar
Internal Medicine

verified

Myocardial infarction (MI), commonly called a heart attack, causes the necrosis of the heart muscle to the part of the heart muscle due to severe reduction or stoppage of blood supply to the heart muscle. If a blood clot blocks the artery, the heart muscle becomes ‘hungry’ for oxygen. Within a short time, heart muscle cells die, causing permanent damage. Although heart attacks are common above 45 years of age in males and 55 years of age in females, the symptoms of a heart attack in females are slightly different from those in males. Heart attacks can be fatal if medical care isn’t received quickly. Also, first-aid for a heart attack can be a life-saver for a person suffering from chest pain, a key symptom of a heart attack. The chest pain is due to the release of chemicals from the oxygen-deficient muscles. Necrosis or muscle damage is reversible if blood supply to the heart is restored within 8-12 hours, so TIME is the key in the treatment of heart attack. Chest pain is due to the release of chemicals from oxygen-deficient muscle cells.

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Symptoms

The symptoms of myocardial infarction include:


 1. Chest pain also known as angina or discomfort occurring right in the centre of the chest. It also feels like a heavy, tight pressure, aching, burning, numbness, squeezing or fullness present for more than a few minutes. It is sometimes mistaken to be indigestion or gas.


 2. A feeling of discomfort in the body's upper areas, including the arms, shoulders, back, joints or stomach


 3. Shortness of breath (difficulty in breathing)


 4. Cold sweating (sweating without the sensation of feeling hot)


 5. Heartburn (feeling of indigestion or fullness)


 6. Feeling nauseated


 7. Vomiting


 8. Feeling dizziness, light-headedness, weakness or anxiety


 9. Irregular heartbeats, usually noticeable 


If you feel any of the symptoms mentioned above for more than 5 minutes, report to a hospital’s emergency section immediately.

Causes And Risk Factors

Causes

The primary reason for a heart attack is the blockage of arteries due to plaque formation. In rare cases, it can result from other medical conditions like congenital abnormalities, rheumatoid arthritis, systemic lupus erythematosus, etc. It can also happen due to cocaine or other drug abuse.

A heart attack is caused when there is blockage of a coronary artery by a blood clot. This blood clot inside the coronary artery occurs due to plaque inside the blood vessels, which causes slow blood flow. If the oxygen demand is greater than the supply, a heart attack may occur even without a blood clot formation.

Symptoms experienced with each heart attack and survival chances depend on the extent of the coronary artery blockage.

Risk Factors

The risk factors of a heart attack include:

Smoking and Uncontrolled Diabetes Mellitus are the leading risk factors for a heart attack in India.

Other factors include:

1. High cholesterol level

2. High blood pressure

3. Family history of coronary artery disease at an early age

4. Obesity

5. Inactive lifestyle

Men have a greater risk of heart disease than women. Menopausal women are at an increased risk of a heart attack.

Prevention

A heart attack can be prevented by just knowing what the risk factors for it are. Check yourself for risk factors like coronary artery disease. Avoid smoking, control your weight, monitor your cholesterol, exercise, keep a strict watch on salt intake, and be compliant with your medicines. Women who are nearing menopause should consider oestrogen replacement therapies.

Diagnosis

Once you visit the emergency department, you will be screened for symptoms, and your evaluation will begin. If the doctors diagnose you with a heart attack, they might order many tests, such as:

1. 12-lead ECG: This is the first test that doctors or paramedics will do; paramedics will be responsible for doing it on-site or on the way to the hospital. The ECG can help you to know what type of heart attack has occurred and where it has occurred. During this time, the heart rate and heart rhythm are monitored continuously with wires connecting your heart to a monitor.

2. Blood tests: Different biochemical markers are noted to check for heart function. These markers are present in your body’s cells. When a part of your heart undergoes an injury, these biochemical markers are released into the bloodstream. Measuring their levels can indicate the size of the heart attack and the timing of it. Doctors can also recommend other blood tests to rule out any other possibilities.

3. Echocardiogram: An echocardiogram can be used during and after the heart attack to learn about the heart's functioning and where the abnormality lies. It also helps to determine if any structures have been damaged during a heart attack.

4. Cardiac catheterisation: Cardiac catheterisation is done during the first hours of a heart attack if the medicines are not doing their job. The catheterisation can identify the blocked artery and help decide which procedure will suit the patients' needs.

Treatment

The treatment for a heart attack begins immediately as the goal is to avoid any more damage to the heart muscle. It includes:

1. Medications: Medications help dissolve the blood clots and avoid the platelets from gathering at the plaque formation site. They also stabilise the platelets and prevent further damage. These medicines are given within 30 minutes of the heart attack to ensure little damage to the heart muscle. These medicines include:


  • Aspirin

  • Statin

  • Heparin

  • Antiplatelet drugs

  • Thrombolytics ( sometimes angioplasty is considered as the choice of treatment. over thrombolytics)


Any other drugs prescribed after your heart attack relieve your heart's pressure, dilate the blood vessels, decrease the pain, and prevent another episode.

2. Interventional procedures: After the heart attack, you may have a cardiac catheterisation to evaluate the condition of your heart, arteries and amount of damage. Sometimes blocked arteries are opened with angioplasty and the use of stents. These procedures are often combined with thrombolytic therapy to open up any blocked arteries or dissolve the clots.

3. Coronary artery bypass surgery: The surgery may be performed when the heart's damage has reached such an extent that there is a need for restoration.

Lifestyle/management

It is normal to feel scared, confused and overwhelmed after a heart attack. To prevent a future episode:

1.Take your medication as prescribed and on time as it is responsible for lowering the risk of another cardiac event. You can use alerts to remember the time of when and which medicines to take.

2. Attend your follow-ups on time and keep track of your symptoms, side effects, etc. so that reporting becomes more efficient.

3. Participate in cardiac rehabilitation, a program curated to help your recovery after a heart attack.

4. It’s okay to feel scared, overwhelmed and confused after a heart attack; try to open up to your near and dear ones as that can help you ease your stress.

5. Try to keep your blood pressure, cholesterol and diabetes in control by exercising, eating healthy food, quitting smoking, having a DASH diet, keeping up the fluid intake and increasing the intake of green leafy veggies and fibrous foods.

Prognosis And Complications

Prognosis

Over the last two decades, there is a lot of improvement seen in people surviving heart attacks. Despite continuous efforts and improving healthcare, many deaths occur as soon as people reach the hospital or get to the hospital. If immediately brought in, the prognosis is excellent. A maximum amount of people feel very good while leaving the hospital in their recovered state.

Complications

You may face complications after a heart attack; they may resolve themselves or may linger around for a long duration of time. These complications may include:

1. Arrhythmia: The natural heart rhythm can be disturbed after a heart attack, for which the doctors can install a temporary pacemaker. A pacemaker is the type of electrode that helps the heart to beat regularly. This electrode is in a small box to be carried around with you. Sometimes it is inserted under the skin.

2. Chest pain: Also known as angina, it usually occurs due to insufficient blood supply to the heart muscle and can occur before or after a heart attack.

3. Heart failure: If your heart has been damaged severely, it affects the pumping action, which results in an inability to meet your body’s demand for oxygen in the blood supply. You may have persistent symptoms like breathlessness, tiredness and bloating. Constant therapy is used to treat these symptoms.

References

1. Heart attack (myocardial infarction) [Updated July 18, 2019]. Cleveland Clinic. Available at: https://my.clevelandclinic.org/health/diseases/16818-heart-attack-myocardial-infarction. Accessed on: March 11, 2021.


2. Heart attack (Myocardial infarction) [Updated Feb 01, 2019]. Harvard Health Publishing. Available at: https://www.health.harvard.edu/a_to_z/heart-attack-myocardial-infarction-a-to-z. Accessed on: March 11, 2021.


3. Heart Attack. Johns Hopkins Medicine. Available at: https://www.hopkinsmedicine.org/health/conditions-and-diseases/heart-attack. Accessed on: March 11, 2021.


4. Life after a heart attack. Heart.org. Available at: https://www.heart.org/en/health-topics/heart-attack/life-after-a-heart-attack#:~:text=After%20a%20heart%20attack%2C%20it's,about%20managing%20your%20risk%20factors. Accessed on: March 11, 2021.


5. Possible complications after a heart attack. CHSS.org. Available at: https://www.chss.org.uk/heart-information-and-support/about-your-heart-condition/common-heart-conditions/heart-attack/possible-complications/. Accessed on: March 11, 2021.

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