The ekg wave or deflection that records atrial depolarization is the?

The deflection/wave is the P wave.

When the SA node triggers a cardiac impulse, the atrial fibers depolarize, producing an electrical change. The pen moves, and at the end of the electrical changem returns to the base position. The first pen movement produces the P wave.

SA node (sinoatrial node/sinuatrial node): A small elongated mass of specialized cardiac muscle tissue just beneath the epicardium. It is in the right atrium near the opening of the superior vena cava, and its fibers are continuous with those of the atrial syncytium.

P wave: The brief zero voltage period in which the impulse is traveling within the AV node and the Bundle of His.

**ECG/EKG or electrocardiogram, is a recording of the electrical changes in the myocardium during a cardiac cycle.

Source:

Hole's Human Anatomy & Physiology. Twelfth Edition. David Shier, Jackie Butler, and Ricki Lewis. Mc Graw Hill - Higher Education. Pages 568-569