This study evaluates the effect of Vitamin D supplementation on ICU and hospital LOS in patients undergoing valve replacement surgery. Half of the patients will receive Alfacalcidol, while the other half-the control group- will be exposed to the same environment without receiving alfacalcidol.

Vitamin D insufficiency has been reported in more than 80% of critically ill patients, hospitalized in intensive care unit (ICU), including cardiac surgical patients. Moreover, 25(OH)D levels continue to decrease from baseline throughout the hospital stay and resolves by 6 months. Vitamin D levels < 20 ng/ml is associated with higher mortality, infection rates and prolonged length of ICU saty.

The discovery of vitamin D receptors (VDR) expressed on cardiac muscle and vasculature, released a strong hypothesis suggesting that vitamin D regulates RAAS activity and cardiac remodeling.

The beneficial effects of vitamin D on cardiovascular system, immune function and wound healing could be of particular interest in critical care, and patients undergoing valve replacement surgery will benefit the most.

Inclusion Criteria:

• patients undergoing mechanical valve replacement surgery

Exclusion Criteria:

• combined valvular replacement surgery and Coronary Artery Bypass Graft (CABG) surgery
• valvular replacement redo
• valvular replacement surgery secondary to infective endocarditis
• on dialysis
• ALT levels 2-3 times higher than normal range
• CHD,
• impaired gastrointestinal function
• indication for vitamin D supplementation within the prior month
• hypercalcemia defined as total calcium >10.4 mg/dl
• hyperphosphatemia defined as serum phosphate > 4.5 mg/dl
• pregnancy and lactation.