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Understand Heart Attack (Myocardial Infarction), Causes, Mechanism, Symptoms

Heart attack or Myocardial Infarction (Myocardium = Heart Muscles/wall, Infarction = Death) is a term used to define the death of a part of the heart wall due to blockage of blood flow. When blood flow is partially blocked it results in myocardial ischemia which manifests clinically as Angina. Prolong Myocardial Ischemia may lead to Mayocardial Infarction.

What is Heart Normal function?

this is a human heart.


Heart function is to Pump blood. and make sure that blood reaches to all parts of the body according to their needs. Blood contains oxygen, nutrients which provide energy, and blood also removes waste materials from the site of formation and take these wastes to the site of excretion (kidneys).

Look at the diagram.

Deoxygenated (poor blood /used blood) from all parts of the body reaches to the right atrium of the heart through superior and inferior vena cavae. Then right atrium contracts and blood reaches to right ventricle then right ventricle contracts and blood is pushed into the pulmonary arteries. pulmonary arteries take the blood to the lungs. In the lungs, blood is purified and oxygenated. The purified and reusable blood then reaches to the left atrium through pulmonary veins. Now the left atrium contract and blood reaches to left ventricle and then left ventricle contracts and blood is pushed into the aorta.
Aorta supplies purified oxygenated blood to all parts of the body from head to feet. and the used blood from the head and upper limbs reach again to the heart via superior vena cava and from rest of the body via inferior vena cava and pumped again

arrows show the movement of blood in heart chambers

movement of blood through heart chambers-diagram

So I hope now u have understood the function of the heart.

What is Heart Attack? 

 To pump blood Heart chambers contracts.
It is obvious that the left ventricle needs more force of contraction because it has to push the blood to all parts of the body. right ventricles only supply lungs for purification purposes. Therefore, the left ventricular wall is thicker as compared to the right ventricular wall.
For contraction, the heart also needs energy and heart muscles must be healthy. Heart muscles also need proper blood supply this blood supply to the heart muscles is provided by coronary arteries, which supply heart muscles and provide them with nutrients and oxygen for performing their pumping action effectively.

A heart attack occurs when blood supply to heart impairs. This may occur as a result of blockage of a branch of a coronary artery by an atherosclerotic lesion or embolus or it may also occur as a result of coronary vasospasm. The symptoms include chest pain which may radiate to the left arm, shoulder and lower jaw. sweating, vomiting, breathlessness and syncope. Patient must be taken to the hospital as soon as possible. It is important that the obstruction must be removed as soon as possible to prevent the death of the ischemic cardiac muscle.

(Note: in medical term, the condition in which the heart fails to pump blood adequately is known as heart failure. In heart failure cardiac output decreases and becomes insufficient, heart attack more appropriately is a term used to define myocardial infarction, it is a condition in which blood supply to heart muscle diminishes which results in the death of the ischemic part of the cardiac muscle, which then heals by scaring. Myocardial infarction or heart attack is a cause of heart failure).

what may be probable reasons behind this.

Causes of Heart Attack.
  1. coronary arteries blockage : 

we know that coronary arteries supply blood to heart muscles. if because of any reason coronary arteries block or become narrow heart muscles exhaust and fail to pump blood. the factor that can block heart coronary arteries include:
  •  Blood Clot. normally blood remains in liquid form in the vessels various factors don't allow the blood to clot. but some times blood clot may form and enter the coronary arteries and may cause their obstruction. 
  • Atherosclerotic plaques: Atherosclerotic plaques are formed by deposition of fats in the walls of vessels. when atherosclerotic plaques form in coronary artery it narrows it lumen or may cause obstruction. which result in decreased or diminished blood supply to heart wall musculature.


    2.  Hypertension: Increased blood pressure, whatever the reason behind causes heart to work more
         and heart contract more forcefully to pump blood with high pressure so High BP may cause weakness of heart muscles and cause heart complications.
    3.  Diabetes (sugar).
    4.  Obesity (fat body)
    5.  kidney problems.
                                   These are the common conditions which may lead to heart failure

Heart attack symptoms


Reducing the risk of a heart attack.

In a nutshell, maintaining a proper diet that is a diet which is balanced and with low-fat content and regular exercise greatly reduces the probability of heart attack. remain healthy and adopt healthy habits, avoid smoking, avoid oily food, avoid much alcohol, avoid non prescribed drugs.


  1. Thank you so much for your very informative article on heart attacks.
    I like not only the information, but your pictures as well.
    My dad passed away from a heart attack long time ago, but I never really knew what causes heart attacks, etc.
    Your article really helped me to understand a lot of things about them.
    Thank you so much for sharing! It's a great piece of information!

  2. Thank you so much for your very informative article on heart attacks.
    I like not only the information, but your pictures as well.
    My dad passed away from a heart attack long time ago, but I never really knew what causes heart attacks, etc.

  3. Heart attack is well explained

  4. Thanks for doing the work and sharing your findings. The more we as a whole help one another, the better we will all be. Fitness is empowering and these seem like some really great blogs that want to help everyone. Thank you again! I think you did an awesome job!

  5. Thanks for your explanation

  6. The first picture is wrong, not the labeling but with the coloring; the color differences between the arteries and the veins could pose to be very misleading and confusing. While we know that arteries carry oxygenated blood and are therefore red, the Pulmonary Arteries are an exclusion and are actually blue in color. Just as veins normally carry deoxygenated blood and are blue, the Pulmonary Veins are also an exception to this rule and are red in color.

  7. Thank you so much Jessica.
    But the first picture don't show the movement of the blood. It explains heart anatomy and structure without blood. but you are absolutely right even then, the pulmonary artery should be blue in colored and pulmonary veins should be red in color. Thank you so much for diverting my attention to this issue.


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