Hello and welcome to HCM,
The dizzy spells that your husband is suffering are unlikely to be associated with the valvular surgery.
Your history suggests some disorder of the inner ear
The inner ear is responsible for maintaining balance.
Any abnormality of the inner ear, an infection, degenerative condition, etc. can lead to disease process in the inner ear.
A complete examination of the inner ear, relevant tests are required.
These tests can only determine the cause of dizziness
and disturbances of maintaining posture.
Thanks and take care.
Dr Shailja P Wahal