Do i need a pacemaker, 73 year old male active, walking 3 mile a day. pulse rate in the 40 to 50 beats a minute?

Unlikely! PulseRate≠: heart rate, may be slower, never faster. Slower rates for someone physically active is c/w lower normal heart size & good heart function. Pacemakers make heart weaker (less well coordinated due to where they stimulate heart muscle); only useful for long pauses, e.g. >2 sec, with symptoms due to low output for given activity. Pacemakers=only a backup; remind heart muscle to contract if too slow.

Bradycardia: That is an abnormally slow heart rate and warrants an evaluation by a cardiologist. A 24 hour Holter Monitor would trace your heart rhythm and rate at rest, with activity and while asleep. This would help determine whether you may need a permanent pacemaker. Your intrinsic pacemaker may be too sluggish, you may have intermittent types of heart block or rate,too slow during exercise.