Wondering If It Is Safe To Have Sexual Relations When

wondering if it is safe to have sexual relations when 83 yr 0ld husband has severe leaking mitral valve(but stable) still walking about 30 min everyday...doing some weights(light) squats ,stretching exercises etc.....He had aortic valve replacement 3yrs ago and doctor says this valve is working 100% ..had bypass surgery 27 yrs ago.He is in good shape except for this valve problem.He looks younger &is active for his age...even doctors say that.