My dad is 69, had bypass surgery 12 years ago, Here lately he has had episodes of fatigue, and dizziness including tonight? 44bpm, is that the cause?

Bradycardia. Slow heart rates can be iatrogenic (due to medications) or natural progression of disease of the heart. He would need a Holter monitor, stress test and thyroid function tests. .
See cardiologist. From what you're describing his symptoms could be related to that very low heart rate, with his history is concerning for possible heart block. Please see his heart doctor right away. If symptoms persist and heart doctor not available, please go to local emergency room.