81 year old male with heart palpitations and a history of regular supraventricular tachycardia(SVT).
Question 1: Why do some beats aberrate?
Question 2: Careful inspection of this tracings suggests 2 populations of RR intervals. What is the significance of this finding?
Question 3: What type of regular SVT does this patient likely have?
-Non-specific ST and/or T wave abnormalities
Question 1: These beats occur relatively earlier and fall in the relative refractory period of the His-Purkinje system. This results in phase 3 block, or rate dependent aberration.
Question2: The presence of two distinct populations of RR intervals during atrial fibrillation suggests the presence of dual AV nodal physiology. Some of the atrial impulses conduct down the slow pathway, while others conduct down the fast pathway.
Question 3: The presence of dual AV nodal physiology makes AVNRT the most likely type of regular SVT for this patient.