Question

Discuss a situation that would cause P waves to be negative in Lead II.

Show an example of a negative P wave in lead II and give an interpretation with your example.

How could you differentiate between atrial fibrillation and sinus rhythm with baseline artifact making the P waves difficult to see?

Answer 1

If the P wave is inverted, it is most likely an ectopic atrial rhythm not originating from the sinus node. Altered P wave morphology is seen in left or right atrial enlargement. The PTa segment can be used to diagnose pericarditis or atrial infarction.

Electrocardiogram showing ST segment elevation in the inferior leads (II, III and aVF), PR segment elevation in aVR and V1 (double-headed arrows), PR segment depression in leads II, III and aVF (single-headed arrows), and P wave axis deviation (67°)

Hearts job is to pump blood to your body.When it's working the way it should, it pumps to a regular, steady beat. This is called a normal sinus rhythm. Each heartbeat starts with a signal from the sinoatrial (SA) node, in your right atrium.

The signal spreads across the right and left atria. That makes them contract and forces blood into your ventricles. Then, the signal moves to the atrioventricular node (AV) node, which is near the middle of your heart.

From there, the signal travels through the ventricle walls. That makes them contract and squeeze blood out of the heart. The right ventricle sends blood to your lungs, while the left pumps it to the rest of your body. The walls then relax and wait for the next signal.

When everything is working smoothly, you have a normal sinus rhythm and your heart beats between 60 and 100 times per minute

Atrial Fibrillation

Sometimes the heart's electrical system doesn't work the way it should. Atrial fibrillation, also called AF or AFib, is the most common type of irregular heartbeat.

In this case, the signals get jumbled. As a result, instead of beating strongly and regularly, the atria quiver. So blood doesn't move into the ventricles very well.