It is a common thing in practice to see patients, relatives and even very educated people making an error in distinguishing between Heart attack and Cardiac arrest and use these words interchangeably. Though one is related to the other as cause of the other essentially these are two different clinical syndromes.
Heart Attack or Myocardial infarction, the scientific synonym of the common man’s lay term of attack or block is nothing but the formation of blood clot within the arteries (coronary) that supply the muscle of the heart. The heart is a muscular pump that pumps almost 5 litres a minute without a halt 24 hours a day and even more as one exercises. But when a person develops a block (plaque) inside the coronary arteries and due to associated lifestyle diseases like hypertension, diabetes, sedentary habits, addictions like smoking, a person builds up a cholesterol laden block within the arteries. The demand of blood supply through the narrowed arteries cannot be met for the oxygenation of heart muscles. This demand and supply mismatch produces a cardiac ischaemic pain and if stressed further can produce a rupture of the plaque ( block) inside the coronary artery to produce a clot within and acutely obstructing the system. Result is total cut off of blood supply to that portion of the heart muscle supplied by the artery- a HEART ATTACK.. With severe pain in chest, arm, jaw, neck and even abdomen along with sweating, sometimes just a burning sensation patient feels fatigued and can even die suddenly. When Death happens due to a heart attack only we call it a CARDIAC ARREST otherwise, heart attack is a condition which gives you time to get an ecg and other assessments to diagnose, start medicines and allows doctors to decide the reopening strategy (revascularization) of the blocked vessel usually with an emergency Angioplasty (primary) or surgery as decided by the results of investigation like echo and angiogram.
In contradiction, CARDIAC ARREST is a sudden abrupt failure of the heart function, it stops beating and in turn leads to cessation of breathing and results in loss of consciousness unless attended urgently with resuscitation measures CPR massage of chest wall with compressions and assisting breath with a bag and mask or a defibrillator paddle often seen in public spaces like malls and stations the person does not revive. Heart attack is only one major cause of cardiac arrest .It may be due to other conditions like electrolyte disturbance rhythm disturbance of the heart slow or very fast needing an electric shock to revive in most cases. Common situation precipitating cardiac arrest are electrocution blunt injury to chest high grade fever with heart involvement especially viral fever ,drowning chronic kidney disease, fluid or blood around the heart .Intense exercise can cause cardiac arrest in hypertrophic thick hearts Cardiomyopathy cases. Many cases of chronic heart failure with previous heart attacks have a high chance of cardiac arrest and sudden cardiac death when stressed due to rhythm disorders developing all of a sudden causing heart to vibrate and stop abruptly electrical silence Cardiac arrest.
Dr. P V Girish
MD DM AFESC FSCAI
Director Heart Failure Clinic & Transplant
Consultant interventional Cardiologist
Metromed International Cardiac Centre