What causes a dip below the baseline in an ekg after the t wave in the opposite direction? it dips down then comes back to baseline until the p wave.

T wave inversion?: Without seeing a picture of the EKG, it's hard to interpret what you're trying to describe. Use HealthTap Prime to upload a picture of the EKG or talk to whoever ordered the EKG for better advice. It seems like the T wave itself (not whatever comes afterwards) would be inverted - T wave inversion. That can be caused by ischemia, although I suppose electrolyte problems can lead to it as well.