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The incidence of congenital heart disease is approximately 1 in 100 newborn births. Although most patients in the past were diagnosed in late childhood or adolescence, widespread use of prenatal diagnosis has improved prenatal detection and significantly impacted detection and early intervention. Development of novel surgical and catheter-based interventions beginning in the 1950s has led to meaningful long-term survival in many patients. In the developing embryo, the cardiac structures are fully formed around 16 weeks of gestation. The early embryologic development of the heart can lead to malformations that are survivable in utero but cause symptoms postnatally. Development of specific cardiac malformations can be traced back to missteps during embryonic development of the heart and vascular structures.
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CLASSIFICATION & NOMENCLATURE
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Lesions can be classified according to their morphology and physiologic presentation. Broadly speaking, congenital heart disease can be divided into the following categories. Details of specific lesions are provided later in the chapter.
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Cyanotic heart defects: Malformations in which blue blood returning from the body passes into the systemic circulation without passing through the pulmonary circulation through a defect in the atrial septum or the ventricular septum of the heart. Some lesions may demonstrate predominant right to left shunting due to obstruction of blood flow to the pulmonary arteries (termed right heart obstructive lesions). Other lesions may manifest with bidirectional mixing of oxygenated and deoxygenated blood flow at the level of the atrium or ventricle without reduction in the amount pulmonary blood flow (termed mixing lesions).
Acyanotic congenital heart defects: Certain forms of congenital heart disease present with pure inflow or outflow tract obstruction without communication between systemic and pulmonary circulations. Other forms of acyanotic congenital heart defects include communication between the systemic and pulmonary circulation with predominant left to right shunt (ie, from systemic to pulmonary circulation). Since the direction of blood flow is from systemic to pulmonary circulation, oxygen saturations are normal. However, the degree of pulmonary blood flow can be elevated in these lesions, resulting in excess pulmonary blood flow and congestive heart failure.
Abnormalities of the great vessels: The extracardiac vessels including aorta and pulmonary artery may demonstrate abnormalities. These include patent ductus arteriosus, coarctation of the aorta, and vascular compression syndromes (vascular rings and slings).
Coronary artery anomalies: A variety of congenital coronary artery abnormalities may be present in isolation or coexist with other forms of congenital heart disease.
Congenital valve disease and abnormalities of ventricular inflow or outflow.
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CYANOTIC CONGENITAL HEART DEFECTS
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Approximately 25% of all congenital heart defects can be classified as cyanotic congenital heart defects. Cyanosis in these conditions results from movement of deoxygenated systemic venous return into the systemic circulation. Lesions are characterized by predominant right to left shunting through defects in the atrial or ventricular septum with downstream obstruction (ie, tetralogy of Fallot and tricuspid atresia). Also included in this category are ...