a) he only has 35% cardiac output b) he only has 35 beats per minute if its the cardiac output ( which is far more likely) what it means that some condition in the heart is causing it to pump blood not quite as effeciently. Basically if you and i had 100%,,, then imagine our entire bodys only getting 35% of that oxygen. Yes, its a pretty serious matter that can have complications from syncope (passing out), or other respiratory disorders, to affect everything up to and including urinary output. * try not to worry too much about his health Likely if he is seeing a cardiologist there are many things that can help with this. Including medications, life-style changes, proper diet, etc etc. There are even surgeries that can now substantially improve mortality rates. There is even a thing thats call ECP Electronic Counter-pulsation therapy.... Its a new intervention that just got implemented at our rural hospital. it has a 66% success rate. Further more, it can reduce medication dependency, and enhance quality of life. Hope I went above and beyond your question: Sincerely, Male cardiac nurse