Abstract
BACKGROUND: Pacemakers attempt to accurately mirror normal physiology; however, even normal pacemaker functionality can have undesirable effects. CASE SUMMARY: A 59-year-old male with a background including heart failure, presented with symptoms of 'hitting a brick wall' during exertion, years following the implantation of a biventricular pacemaker for third-degree atrioventricular block. He was extensively evaluated, with cardiopulmonary exercise testing and simultaneous device interrogation. After reaching a heart rate of 140 beats/minute, continued exercise resulted in Wenckebach phenomenon and progression to sustained 2:1 atrioventricular block with immediate reductions in oxygen consumption. Ultimately, the aetiology was attributed to upper rate behaviour, rather than the progression of heart failure, and resolved with simple device reprogramming. DISCUSSION: Cardiopulmonary exercise testing is an invaluable tool when evaluating patients who present with cardiovascular symptoms. Device reprogramming is often required, including the use of rate-response algorithms where appropriate. Personalisation is key, with programming tailored to the individual's physiology.