12 lead ECG of an uncommon form of an atrioventricular nodal reentrant tachycardia

The 12 lead ECG shows a regular, narrow complex tachycardia at a rate of 130 beats per minute. The QRS complexes are normal. There is an abnormal "notching" within the ST segment, representing a retrograde P wave (*). The interval from the proceeding R wave (RP interval) is longer than the PR interval; this is a "long RP tachycardia," due to an atypical atrioventricular nodal reentrant tachycardia.

Normal electrocardiogram showing normal sinus rhythm at a rate of 75 beats/minute, a PR interval of 0.14 seconds, a QRS interval of 0.10 seconds, and a QRS axis of approximately 75°.