Hello,
Thanks for writing to Health Care magic, I am Dr , Muhammad Ahmad , I have read your question closely, I understand your concern and will be helping you with your health related problem.
Permanent pacemaker is a device which is essential for life and has to stay there for decades so it needs to be placed at a stable place in body and as you said your father is thin so it was placed under his muscle. When a device is placed under skin it does cause local pressure effects and inflammation.
As
drainage of arm is passing through pectoral region so local pressure effects and inflammation may press on drainage system and causes swelling, local inflammation itself causes swelling, this is quite common in the earlier days after placement of the device.
But this usually settles in 15 days , if this doesn't get better in 15 days , I would advise you to contact your doctor to look for the reason of swelling and proceed further for its workup and treatment. If it starts regressing then well and good let it take natural course.
I hope this answered your question, If you have more queries I am happy to answer you.
Regards.
Dr.Muhammad Ahmad