27th July 2020

A fit 25-year-old endurance runner undergoes an electrocardiogram (ECG) as part of a routine check-up

A fit 25-year-old endurance runner undergoes an electrocardiogram (ECG) as part of a routine check-up. He is told that he has something called ‘sinus arrhythmia’. 

Which of the following ECG findings is most consistent with this diagnosis?

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