ECG Leads and Their Importance

What do bipolar limb leads (I, II, III) record in an ECG?

• Between 2 electrodes

• Across the chest

• One limb electrode vs average of others

• Complete 3D mapping

Which leads are placed across the chest to give a horizontal plane view in an ECG?

• Bipolar limb leads

• Unipolar limb leads

• Chest (precordial) leads

• 12-lead ECG

What is the clinical importance of a 12-lead ECG?

• Records between 2 electrodes

• Provides complete 3D mapping of cardiac activity

• Compares one limb electrode vs average of others

• Gives a horizontal plane view

Which of the following is a characteristic of unipolar limb leads (aVR, aVL, aVF)?

• Record between 2 electrodes

• Compare one limb electrode vs average of others

• Placed across chest

• Provide complete 3D mapping

What does the heart generate during depolarization and repolarization?

• Magnetic fields

• Electrical currents

• Sound waves

• Light pulses

What is the role of electrodes in an ECG?

• To amplify sound

• To detect potential differences

• To measure temperature

• To record heart rate

How does an ECG machine record electrical activity?

• As sound waves

• As light patterns

• As deflections on graph paper/screen

• As temperature changes

What happens when a depolarization wave moves towards a positive electrode?

• Downward deflection

• No deflection

• Upward deflection

• Sideways deflection

What occurs when a depolarization wave moves away from a positive electrode?

• Upward deflection

• Downward deflection

• No deflection

• Circular deflection

What does the P wave represent in an ECG?

• Ventricular depolarization

• Atrial depolarization

• Ventricular repolarization

• Atrial repolarization