Dear student.
Heart attack occurs when the flow of oxygen rich blood is blocked from reaching to a part of heart.
The cause of heart attack is the blood clot that blocks one of the coronary arteries which bring blood and oxygen to the muscles of the heart.When there is lack of oxygen supply to the heart then it leads to heart attack. We can prevent heart diseases by adopting a healthy life style such as exercise, no smoking, healthy diet, and maintain constant weight.
a. Hand is used to press the heart in a pumping motion to restore a pulse or chest compressions without artificial ventilation. This might bring the heart beat back and the person can get time for medical treatment.
b. This might be due to the sudden pain a person experience in heart, before or during the heart attack.
Regards.