EKG Only PowerPoint 1 Cardio

Cardiology Exam 1

Basic (3‐Lead) Electrocardiogram (ECG)

Four electrodes are placed on both of the patient’s arms and on the left leg.

.

The potential difference recorded between the electrodes on the person’s left arm (LA) and right arm (RA) is called lead I of the ECG.

.

The other limb leads are recorded between the right arm and left leg (lead II) and left arm and left leg (lead III).

Basic (3‐Lead) Electrocardiogram (ECG) (Photo)

Basic Electrocardiogram (ECG) Parts (8)

1. P wave

2. QRS complex

3. T wave

4. PQ segment

5. PR interval

6. ST segment

7. ST interval

8. QT interval

P wave

Depolarization of the atria

QRS complex

Depolarization of the ventricles

T wave

Repolarization of the ventricles

PQ segment

Time when the impulse is traveling through the AV node, bundle of His, and bundle branches

PR interval

Onset of P wave to middle of QRS complex

ST segment

End of QRS complex to onset of T wave

ST interval

End of QRS complex to end of T wave

QT interval

Onset of QRS complex to end of T wave

Overdrive Suppression

- The AV node and the Purkinje fibers are LATENT PACEMAKERS that may exhibit automaticity and override the SA node if it is suppressed.

.

• The intrinsic rate of phase 4 depolarization (and heart rate) is FASTEST in the SA node and SLOWEST in the Purkinje fibers.