This tracing is from the same patient, recorded one day after discontinuing digitalis. The ectopic atrial tachycardia and AV block indicative of digitalis toxicity are no longer present. The atrial rate is now 60/min and every P wave is conducted to the ventricles with a PR interval that is only slightly prolonged (0.22 seconds). The P wave morphology is now normal and the P wave axis is +30 degrees, indicating that the P waves are originating in (or very close to) the sinus node.