Vitamin D deficiency in surgical congenital heart disease: prevalence and relevance

Abstract

Vitamin D is a pleiotropic hormone important for the proper functioning of multiple organ systems. An emerging body of adult and pediatric critical care literature strongly suggests that vitamin D deficiency contributes to secondary organ pathophysiology, prolongs ICU stay, and worsens outcome in critically ill populations. Recent clinical studies suggest that a significant number of children with congenital heart disease (CHD) have post-operative vitamin D deficiency which appears to be associated with greater cardiovascular dysfunction. Altogether the cumulative body of literature suggests that peri-operative optimization of vitamin D status has the potential to speed recovery and/or improve outcome. This review describes the epidemiological and basic science research linking vitamin D deficiency to post-operative organ dysfunction. Furthermore, the available supplementation approaches are reviewed in the context of prevention of post-operative vitamin D deficiency and avoidance of toxicity in the majority of CHD patients. Finally, knowledge gaps regarding vitamin D supplementation are identified and the next stages for research are outlined.

Keywords: 25 hydroxyvitamin D; Vitamin D deficiency; cardiopulmonary bypass; congenital heart disease(CHD); surgery; toxicity; vitamin D supplementation.

Figure 1

Overview of vitamin D parathyroid renal axis—Functioning of the axis is demonstrated in the context of calcium homeostasis. In response to low calcium, the parathyroid glands increase parathyroid hormone (PTH) secretion. Increased PTH leads to activation of vitamin-D through an inducible renal enzyme, converting 25 hydroxyvitamin D (25OHD) to the active hormone or 1,25 dihydroxyvitamin D (1,25OH₂D).

Figure 2

Factors contributing to a vitamin D deficient state. Demonstrates some of the congenital and acquired factors that could impair vitamin D axis functioning following cardiac surgery for congenital heart disease.

Figure 3

Vitamin D deficiency mediated pathophysiology relevant to post-operative congenital heart disease patients. Demonstrates some of the mechanisms through which the vitamin D axis could contribute to the pathophysiologies commonly observed following cardiac surgery.