Andersons pediatric cardiology 284

Abstract Examination of the frequency of congenital cardiac disease has very important implications for clinical diagnosis and management and for studying the etiology and burden of congenital heart disease In this chapter we explore some important definitions and etiologic considerations and we review the available literature on the reported prevalence of congenital heart disease The question “how much congenital heart disease” continues to evolve in the face of improving prenatal diagnosis, options for early pregnancy termination and better survival outcomes Most studies report a prevalence of congenital heart disease of 0.2–2% among newborns and the variability is due to the methods used to screen for and to ascertain the diagnosis The burden of congenital heart disease is now expanding to adult medicine as many patients with repaired congenital heart disease are surviving to adulthood As an example, a recent study estimated that in year 2010, there were 2.4 million people in the United States with congenital heart disease; of them, 1.4 million are adults and 300,000 had severe disease With the greater potential need for reoperation and care during follow-up, an economic and logistical burden can be expected in the future in adults with congenital heart disease Keywords Prevalence; incidence; rates; prenatal diagnosis; adults with congenital heart disease Introduction Examination of the frequency of congenital cardiac disease, either as a rate or as a proportion, has important implications for the study of congenital cardiac malformations, as well as their clinical management However, there is much confusion and misuse regarding terminology and methodology, with important implications for the accuracy, validity, and comparability of findings reported in the published literature Knowledge of how critically to appraise these reports is important in defining their value when applied to issues of diagnostic likelihood, surveillance and trends, etiologic associations, burden of disease, and requirements for resources These issues have more recently been impacted by fetal diagnosis and termination, with individual decisions influenced by contemporary estimates of prognosis related to the natural and modified natural history As more patients survive into adulthood, estimates of the burden of disease, and the requirements for resources, have also achieved greater importance Therefore the question of “how much congenital cardiac disease?” continues to evolve Providing the correct answer has important relevance for both the providers of health care and the health care system itself Definitions In considering and discussing the prevalence of congenital heart disease, key terms to be defined include congenital cardiac disease itself, frequency, ratio, proportion, rate, incidence, and prevalence Congenital Cardiac Disease In examining reports of congenitally malformed hearts, it is important to know how the lesions were defined and what conditions were included or excluded However, the definitions in Table 13.1 do not address all controversy There is no current consensus as to whether several groups of lesions should be considered to represent congenital cardiac malformations because they do not manifest clinically until later in life These conditions include genetic conditions, arrhythmic conditions, primary cardiomyopathies, and structural defects that do not have functional importance in many, but not all, circumstances Considerations regarding the inclusion or exclusion of these lesions are important because these lesions are common and their inclusion might inflate a prevalence estimate Comparability of previous reports has somewhat suffered from a lack of common nomenclature regarding the description and classification of congenital heart defects To some extent, there has been important work in consolidating nomenclature toward an internationally accepted standard, which may facilitate future work.1–3 Table 13.1 Clinical Definitions Used in Identifying the Frequency of Congenital Cardiac Disease Term Definition and Examples Congenital cardiac A gross structural abnormality of the heart or intrathoracic great vessels that is actually or disease potentially of functional significance.26 Excludes normal variants without functional consequence (e.g., persistent patency of the left superior caval vein, or abnormal patterns of branching of the systemic arteries) Genetic conditions Present from conception and may not have manifest cardiovascular consequences until much later in life (e.g., Marfan syndrome, Williams syndrome, and hypertrophic cardiomyopathy) Arrhythmic Abnormalities at the physiologic or ultrastructural level that result in arrhythmias (e.g., long conditions QT syndrome and ventricular preexcitation) Primary Myocardial structural abnormalities with a genetic or metabolic etiology (e.g., hypertrophic cardiomyopathies cardiomyopathy and ventricular noncompaction) Structural defects Defects that do not have functional significance in many, but not all, circumstances or