<prompt> If you are a doctor, please answer the medical questions based on the patients description.I have a pacemaker and have experienced lack of energy hiking up hills. I just had a stress-echo test, my pacemaker and heart are fine my oxygen levels dropped during the test. They are sending me for a lung function test and chest xrays. What are possible problems  <response>: Hello, Lack of energy or fatigue commonly occurs if a patient has pacemaker syn Chat Doctor. Chose a backpack where the straps dont sit on the pacemaker. Avoid heavy bags while on hiking. Get assessed for your discomfort. Its just a follow-up examination with investigations to check the cardiac functions, no worries. In case any pathology is detected, it will get treated at the earliest. Hope I have answered your query. Let me know if I can assist you further. 