INTRODUCTION

Introduction

Anomalies of the cardiovascular system—either in structure or function—present at the time of birth represent a group of conditions known as congenital heart defects (CHD). These defects represent an arrest in embryogenesis sometime around the 5th to 10th weeks of gestation. During this time, the cardiac tube structure develops, rotates on itself, and refines the 4 individual chambers as well as the 2 separate circulations of the heart.

Traditionally, the majority of CHD have been believed to be multi-factorial in origin. However, recent advances in molecular biology are now suggesting “point mutations” may be a causative factor for a higher percentage of defects than previously thought. In truth, the origin may never be definitively known. However, factors that have been associated with an increased incidence of CHD include:

	Exposure to toxins during pregnancy E.g., alcohol, lithium, amphetamines, anticonvulsants
	Exposure to infectious agents E.g., rubella
	Maternal age greater than or equal to 40
	Maternal health (e.g., insulin-dependent diabetes, lupus)
	Genetic aberrations E.g., Down Syndrome, Turner’s Syndrome
	Sibling and/or parent with CHD Increases risk by 1-3%
	Association with other congenital anomalies E.g., TE Fistula, renal agenesis, diaphragmatic hernia, fetal alcohol syndrome

Other than prematurity, CHD are the major cause of death in the 1st week of life and have an occurrence rate of ~ 0.8-1% of all live births. Estimates of occurrence by specific lesion vary with how the data are obtained; despite this, it is apparent that ventricular septal defect (VSD) is the most common congenital defect occurring in ~ 30% of all patients with CHD. The incidence of CHD in other countries is distinctively similar to that of the United States. CHD are predominately a male disorder—2:1 or 3:1 ratio, depending on your source. The exceptions are the Patent Ductus Arteriosus (PDA) & the Atrial Septal Defect (ASD) which are seen predominately in females.

While many infants born with cardiac anomalies do not have a life threatening defect, ¹/₃ will have critical disease—those requiring cardiac catheterization or cardiac surgery—and will have an increased mortality within the 1st year of life. Alterations in normal cardiovascular development can and does interfere with the transition from intra-uterine to extra-uterine life. However, with early detection, intervention and management, the majority of infant’s born with CHD can be expected to survive infancy and beyond.