Hello, welcome to healthcaremagic. Feeling of increased heart rate
could be due to cardiac disroders in old age, but as you said your doctor has ruled them out they could be due to panic disorder too. But to confirm that more information is needed which you haven't mentioned. A panic attack
is a sudden surge of overwhelming anxiety
and fear. Your heart pounds and you can’t breathe. You feel dizzy and sick to your stomach. You may even feel like you’re dying or going crazy. You should consult your doctor to ascertain the real cause. Wish your father a good health.