How to Mend a Broken Heart

By: Cam Leveille

Congenital heart defects (CHD) are defined as the presence of structural abnormalities of the heart present from birth. It can be estimated that the incidence of these defects occur within 1-2% of all live births and also account for 28% of all birth defects [1, 2]. CHDs are difficult to diagnose until symptoms become present. However, suspected CHDs can be identified in utero with obstetric screening through the use of an ultrasound and are able to be corrected for almost all individuals at a young age [3]. In addition, the use of surgical interventions for CHDs have greatly improved the survival rate of children born with these defects [4].

The severity of various CHDs are dependent on specific structural impairments and therefore can either be simple or complex [5]. Simple defects can range from a hole in the septum, allowing oxygenated and deoxygenated blood to mix, or a narrowed valve that prevents normal blood flow. This can have implications on the child’s life such as fatigue, shortness of breath and poor growth and development [6]. In contrast, complex heart defects are more severe and stem from multiple problems associated with the locations of major cardiac structures. This has more serious implications such as discoloration of the skin due to lack of oxygenated blood, clubbing of hands and feet and potentially death [6]. Each defect, whether simple or complex, has its own unique prognosis and treatment options [5].

Simple heart (non-cyanotic) defects include holes in the wall of the heart or narrowed vessels. Atrial and ventricular septal defects (VSD) are examples of heart defects of the heart or vessel wall structure allowing for oxygenated blood to mix with deoxygenated blood before it can travel to the lungs or systemic circulation [5]. Typically these defects are closed and repaired using surgical procedures [7]. Other simple heart defects involve the heart valves that control the flow of blood between different chambers. Weakening or stiffening of these valves prevents normal blood flow through the heart and are associated with heart murmurs, enlargement of the ventricles (hypertrophy) and hypertension [5]. Calcified and weak valves that do not allow for blood flow must be repaired through valve replacement surgeries [8].

More complex (cyanotic) heart defects typically present as two types: tetralogy of fallot (TOF) or transposition of the great vessels (TGV). Children born with TOF present with a combination of four defects: pulmonary valve stenosis, a large VSD, a defect within the aortic wall that allows deoxygenated blood to flow directly into the aorta instead of the pulmonary artery, and right ventricular hypertrophy [5]. TGV is an abnormal arrangement of the great vessels, typically presented as an inversion of the pulmonary artery and the aorta. Therefore, TGV prevents oxygenated blood from entering systemic circulation [5]. Each of these conditions are life threatening and must be repaired through open-heart surgery at the time of birth [9].

CHD remains a relevant issue today even though the majority of these conditions are corrected by birth [10]. Procedures remain complex and invasive to the individual. Furthermore, CHDs are a broad category of defects and each one comes with its own symptoms and risks [10]. Hopefully future research can find less invasive and easier ways to treat this burdensome disease.


References:

[1] Hoffman, J. I., & Kaplan, S. (2002). The incidence of congenital heart disease. Journal of the American college of cardiology39(12), 1890-1900.

[2] Dolk H, Loane M, Game E, for the European Surveillance of Congenital Anomalies (EUROCAT) Working Group. Congenital heart defects in Europe prevalence and perinatal mortality, 2000 to 2005. Circulation 2011;123:841-9

[3] Landis, B. J., Levey, A., Levasseur, S. M., Glickstein, J. S., Kleinman, C. S., Simpson, L. L., & Williams, I. A. (2013). Prenatal diagnosis of congenital heart disease and birth outcomes. Pediatric cardiology34(3), 597-605.

[4] Warnes, C. A., Liberthson, R., Danielson, G. K., Dore, A., Harris, L., Hoffman, J. I., … & Webb, G. D. (2001). Task force 1: the changing profile of congenital heart disease in adult life. Journal of the American College of Cardiology37(5), 1170-1175.

[5] Lilly, L. S. (2012). Pathophysiology of heart disease: a collaborative project of medical students and faculty. Lippincott Williams & Wilkins.

[6]Mann, D. L., Zipes, D. P., Libby, P., & Bonow, R. O. (2014). Braunwald’s heart disease: a textbook of cardiovascular medicine. Elsevier Health Sciences.

[7] Horvath, K. A., Burke, R. P., Collins, J. J., & Cohn, L. H. (1992). Surgical treatment of adult atrial septal defect: early and long-term results. Journal of the American College of Cardiology20(5), 1156-1159.

[8] Luciani, G. B., De Rita, F., Lucchese, G., Hila, D., Rungatscher, A., Faggian, G., & Mazzucco, A. (2012). Repair of congenitally dysplastic aortic valve by bicuspidization: midterm results. The Annals of thoracic surgery94(4), 1173-1179.

[9] Nollert, G., Fischlein, T., Bouterwek, S., Böhmer, C., Klinner, W., & Reichart, B. (1997). Long-term survival in patients with repair of tetralogy of Fallot: 36-year follow-up of 490 survivors of the first year after surgical repair. Journal of the American College of Cardiology30(5), 1374-1383.

[10] van der Bom, T., Bouma, B. J., Meijboom, F. J., Zwinderman, A. H., & Mulder, B. J. (2012). The prevalence of adult congenital heart disease, results from a systematic review and evidence based calculation. American heart journal164(4), 568-575.

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