Myocardial infarction (MI) is a term used by medical fraternity for a condition which is commonly referred as heart attack. Myocardial infarction is a serious and life threatening condition arising from atherosclerotic changes in the coronary vessels. Heart attack occurs when the blood flow from the coronary artery is blocked and the heart muscles do not get enough blood supply. As a result the heart muscles get damaged or die. The whole event is sudden in onset.
In heart attack one or more than one artery is blocked due to buildup of plaque. Plaque is made up of cholesterol, fat, calcium and other waste materials. Moderate to severe chest pain, breathlessness, dizziness, nausea, perspiration at rest and fainting are some of the signs of myocardial infarction. In some cases the pain may radiate to left hand, neck and jaw. However, at least 25 to 30 percent of MI occurs without any warning signs.
Myocardial infarction is diagnosed with changes in electrocardiogram (ECG), blood trophonin and symptoms. It takes almost 6 hours for progression of damage from one layer of heart muscle to another. Hence any intervention within 6 hours of heart attack is critical to reduce damage to the heart muscles. This crucial period is called “time window”.
Signs And Symptoms Of Myocardial Infarction
The presenting symptoms may vary from severe pain in chest to minimum symptoms and the condition remaining unrecognized. Especially in diabetics the symptoms may remain subtle. In most patients pain begins in middle of chest or below the breast bone and spreads to left side of chest. The pain may be varying in intensity. It may also radiate to left arm, neck, back and jaw.
Pain is accompanied with heavy sweating. Pain lasts for more than 20 minutes or more and patient does not get relief even after taking medicine that helps to dilate the coronary artery or with rest. Following are classical symptoms of myocardial infarction:
- Feeling of compression and tightness in chest. Patient feels as if someone is sitting on his chest.
- Severe sweating even if the patient is resting.
- Nausea and vomiting
- Rapid heartbeats
- Pain in left hand, neck, jaw and back.
- Feels like burning sensation in stomach and fullness of stomach.
Causes And Risk Factors Of Myocardial Infarction
Myocardial infarction occurs due to blockage in the coronary artery. This prevents blood perfusion in the heart muscles and ultimately without oxygenated blood the heart muscles die. The heart is made up of special muscles. Heart has individual blood vessels that supply blood to heart muscles. These blood vessels are called coronary arteries. There are two coronary arteries; left and right coronary artery. They originate from the aorta. These two arteries have several smaller branches that take blood throughout heart muscles.
In myocardial infarction, the coronary artery or its branch gets blocked. As a result the particular part of heart muscle remains devoid of blood supply. It can lead to death of the muscle tissue of that particular portion of heart. If one of the main coronary artery is blocked then large part of heart muscle is in danger of getting damaged. Certain factors increase the risk for myocardial infarction. They are:
- Increase in LDL (low density lipoprotein). It is also called bad cholesterol. LDL cholesterol has tendency to stick to walls of arteries and form a plaque. Plaque can narrow the coronary artery and sometime it may completely block the vessel causing complete obstruction leading to heart attack.
- Eating saturated fats can increase LDL. Saturated fat is present in red meat, cheese, butter, processed foods, and palm oil.
- High blood pressure
- High triglyceride level. Triglyceride is also a type of fat.
- The risk of heart attack increases as the person grows older. Men are at greater risk after the age of 45 where as women have increased risk after the age of 55.
- People having family history of heart attack.
- Lack of exercise or living sedentary lifestyle.
- Increased stress
Diagnosis And Treatment Of Myocardial Infarction
To diagnose whether the patient has myocardial infarction, the doctor will examine the patient first. He will measure his blood pressure and heart rate. If he suspects the symptoms of heart attack he will recommend electrocardiogram (ECG). When person has heart attack the ECG shows abnormal findings. Blood test such as blood troponin will reveal abnormal results if the heart muscles are damaged. This all things will be useful in acute case of myocardial infarction. Other diagnostic procedures include angiogram and echo-cardiogram.
Acute myocardial infarction is serious condition which requires immediate treatment. Delay in treatment can be life threatening. Most of the people need emergency treatment. The normal treatment measures in the emergency room include as follows:
- Oxygen is given through mask or nasal prongs.
- Anxiety and pain are relieved with reassurance and medications.
- Thrombolytic therapy is given if the patient is seen within 6 hours after the onset of chest pain. In this therapy medications are given that help to dissolve the clot.
- Anti platelet medicines are administered to prevent formation of new clots in the coronary artery.
- Beta blockers and ACE inhibitors help to lower blood pressure so that heart muscles can relax.
- Straining at stool is avoided. Patient is given mild laxative.
- Patient is given semisolid diet for first 48 hours in the hospital.
- If patient is stable walking is started from 5th or 7th day.
- If there are no complications, patient may be discharged from the hospital on tenth day.