Electrocardiogram - Working, Components & Clinical Significance

An electrocardiogram (ECG or EKG) is a non-invasive diagnostic test that records the electrical activity of the heart over time.
It is commonly used to detect and analyze heart-related problems, including abnormal rhythms, inadequate blood flow, and structural issues.

How an ECG Works:

The ECG measures the electrical changes on the skin produced by the depolarization and repolarization of the heart muscle during each cardiac cycle.
Electrodes are placed on the chest, arms, and legs to detect these signals, which are then transmitted to an ECG machine.
The machine displays the electrical signals as a series of waves on a screen or on printed paper.

P Wave:
- Represents atrial depolarization, the process when the atria contract and pump blood into the ventricles.
QRS Complex:
- Represents ventricular depolarization, which occurs when the ventricles contract and pump blood out of the heart.
- It consists of:
  1. Q wave: A small downward deflection.
  2. R wave: A tall upward deflection.
  3. S wave: A small downward deflection following the R wave.
T Wave:
- Represents ventricular repolarization, the phase when the ventricles recover from contraction and prepare for the next cardiac cycle

Arrhythmias: Abnormal heart rhythms.
Myocardial infarction: Heart attack.
Ischemia: Reduced blood flow to the heart muscle.
Cardiomyopathy: Disease of the heart muscle.
Heart valve problems: Issues with the function of the heart valves.
Pericarditis: Inflammation of the sac around the heart.
Electrolyte imbalances: Abnormalities in the body’s electrolytes, such as potassium or calcium.

An ECG is a quick, painless, and low-risk
It provides essential information about heart health and is often done as part of a routine physical exam or to investigate symptoms like chest pain, shortness of breath, or palpitations.