You say your pulse is 40-48 and this sounds terribly like your doctor has put you onto beta-blockers. They have exactly the side-effects you describe,- low pulse rate, plus many more, -tiredness
, general malaise, impotence
, but mainly many more patients die who are on them than other anti-hypertensive drugs.
Your doctor is unconcerned because he's got lots of other patients. Reducing the dosage is immaterial because they're not dosage-sensitive.
IF you're on beta-blockers (they nearly all have names ending in "----OLOL " such as Atenolol, Propranolol
, etc) I'd sincerely urge you to wean yourself off them, beginning now. DON"T suddenly stop taking them, because you'll get a beta-blocker Bounce" effect... Just decrease the dosage, and take them less frequently until you're completely off them.
Beta blockers have been officially withdrawn in UK as first-line treatment for so-called hypertension
( in 2006) due to the horrendously high mortality rate
they caused, in the largest-ever test-trial ever conducted (the ASCOT Trial). In due course they'll be withdrawn in other countries.