25th May 2025

A 34-year-old female presents for a routine health check with an ECG showing a PR interval of 250ms.

A 34-year-old female presents for a routine health check with an ECG showing a PR interval of 250ms. She has narrow and regular QRS complexes with all QRS complexes following a p-wave. 

Which cardiac structure is responsible for this condition?

Select the SINGLE most appropriate option from the list below. Select ONE option only.