RCCS key terms

The fetal circulatory pattern in which oxygenated blood from the placenta reaches the heart through the umbilical vein, bypassing the lungs via the foramen ovale and ductus arteriosus. Right ventricular output is high, and pulmonary blood flow is low.

An opening in the atrial septum that allows right-to-left flow in the fetus. After birth, falling pulmonary pressures and rising left atrial pressure normally close it functionally; incomplete closure leaves a patent foramen ovale.

A fetal vessel connecting the pulmonary artery to the descending aorta, shunting blood away from the lungs. After birth it constricts as oxygen rises and prostaglandins fall, becoming the ligamentum arteriosum.

The period after birth when pulmonary vascular resistance falls and systemic resistance rises, reversing ductal and atrial shunt directions. Understanding this helps interpret early neonatal echocardiograms and explains persistent fetal patterns.

Resistance to blood flow through the pulmonary vessels. It is high in the fetus, falls rapidly after birth, and later declines further; persistent elevation can maintain right-to-left shunting or cause right heart failure.

The normal arrangement of thoracic and abdominal organs, with the morphologic right atrium and liver on the right and the stomach and morphologic left atrium on the left. It is a key descriptor in congenital heart disease.

In a normal heart the tricuspid valve inserts closer to the apex than the mitral valve. This offset helps identify ventricular morphology and is lost or altered in defects such as atrioventricular septal defect.

In normal anatomy the pulmonary artery arises anteriorly from the right ventricle and crosses over the aorta, which arises posteriorly from the left ventricle. Loss of this crossing suggests transposition or double outlet right ventricle.

Blood flow from the systemic to the pulmonary circulation through an abnormal connection, increasing pulmonary blood flow. It may cause pulmonary overcirculation, heart failure, and eventually pulmonary vascular disease.

Blood flow from the pulmonary to the systemic circulation, delivering desaturated blood to the body and causing cyanosis. It occurs with elevated pulmonary resistance or obstructive right heart lesions.

Pulmonary vascular disease that develops after long-standing left-to-right shunting, raising pulmonary resistance until shunt flow reverses to right-to-left. It causes cyanosis and makes shunt closure contraindicated.

Congenital heart disease in which survival after birth depends on a patent ductus arteriosus for pulmonary or systemic blood flow. Examples include pulmonary atresia and hypoplastic left heart syndrome.

A conotruncal defect with a ventricular septal defect, overriding aorta, right ventricular outflow obstruction, and right ventricular hypertrophy. The obstruction determines cyanosis and dictates timing of repair.

An opening in the ventricular septum allowing blood to cross between ventricles, usually left to right. Size and location determine shunt volume, pulmonary overcirculation, and the potential for spontaneous closure or heart failure.

A spectrum of underdevelopment of left-sided structures including the mitral valve, left ventricle, aortic valve, and aorta. Systemic perfusion depends on the ductus arteriosus, and staged palliation is required.

A conotruncal defect in which the aorta arises from the right ventricle and the pulmonary artery from the left ventricle, creating parallel circulations. Survival depends on mixing through an atrial septal defect or ductus arteriosus.

A defect involving the atrial and ventricular septa and a common atrioventricular valve, often associated with Down syndrome. It causes left-to-right shunting and atrioventricular valve regurgitation, and surgery is usually needed in infancy.

A heart with one dominant functional ventricle receiving both systemic and pulmonary venous return. Long-term management typically involves staged palliation culminating in the Fontan circulation.

Abnormal arrangement of organs across the body, often with complex congenital heart disease such as atrioventricular septal defect, anomalous pulmonary venous return, or single ventricle. It is classified as right or left atrial isomerism.

A narrowing of the aortic isthmus that obstructs systemic blood flow, causing upper extremity hypertension and lower extremity hypoperfusion. In neonates it may be ductal dependent and present with shock.

A display artifact on color or spectral Doppler when blood velocity exceeds the Nyquist limit, causing the signal to appear on the opposite side of the baseline. Adjusting scale, baseline, or transducer frequency can reduce it.

The maximum Doppler frequency shift that can be unambiguously displayed at a given pulse repetition frequency. Exceeding it causes aliasing; it is higher with continuous-wave Doppler, which does not alias.

A Doppler mode that transmits and receives continuously, measuring high velocities without aliasing but without depth discrimination. It is used to measure stenotic and regurgitant jet velocities.

A real-time display of mean blood velocity and direction overlaid on the two-dimensional image. It helps locate shunts, regurgitation, and stenotic jets, but is qualitative and dependent on settings.

A Doppler mode that samples velocity at a specific depth using range gating, providing depth localization but limited maximum velocity before aliasing. It is useful for low-velocity flow and shunt timing.

As Low As Reasonably Achievable: the principle of minimizing ultrasound exposure by reducing output, exposure time, and unnecessary imaging while obtaining diagnostic information. It is especially important in fetal and pediatric echocardiography.

The ratio of pulmonary to systemic blood flow, calculated from ventricular outflow stroke volumes or Doppler data. A ratio above 1.5 suggests a significant left-to-right shunt; below 1 suggests right-to-left shunting.

The simplified relationship that pressure gradient equals four times the square of peak velocity. Echocardiographers use it to estimate gradients across valves, shunts, and obstructions.

The narrowest cross-section of a regurgitant or stenotic jet just downstream of the orifice. Its width on color Doppler estimates lesion severity, with wider measurements indicating more severe regurgitation or stenosis.

Proximal isovelocity surface area: a color Doppler method that estimates flow through a narrowed orifice by measuring the radius of a hemispheric shell where velocity is known. It helps quantify regurgitant volume and effective orifice area.

A standardized measurement expressing how many standard deviations a structure's size lies from the mean for body surface area or gestational age. It is used to define hypoplasia and track growth.

A Doppler measurement used to estimate right ventricular systolic pressure from the Bernoulli equation, adding right atrial pressure. It helps assess pulmonary hypertension and right heart pressures.

A medication that keeps the ductus arteriosus open in neonates with ductal-dependent congenital heart disease. It is given urgently to preserve pulmonary or systemic blood flow while planning intervention.

A catheter procedure that enlarges the atrial septal defect by pulling an inflated balloon across the septum, improving mixing in transposition or obstructed pulmonary venous return. It is often performed urgently in neonates.

The first-stage palliation for hypoplastic left heart syndrome, creating a neoaorta from the pulmonary artery and a systemic-to-pulmonary shunt or right ventricle-to-pulmonary artery conduit. It is followed by Glenn and Fontan stages.

A cavopulmonary anastomosis connecting the superior vena cava to the pulmonary artery, directing upper body venous blood to the lungs. It is the second-stage palliation for single ventricle physiology.

A staged surgical circulation in which systemic venous blood flows directly to the pulmonary arteries without a ventricular pump, typically via a total cavopulmonary connection. It is the final palliation for single ventricle.

Surgical repair of transposition of the great arteries in which the aorta and pulmonary artery are transected and reconnected to the correct ventricles, with coronary artery transfer. It is usually performed in the first weeks of life.

A surgical connection between a systemic artery and the pulmonary artery that provides pulmonary blood flow in cyanotic lesions with reduced pulmonary flow. It is later taken down during corrective or staged surgery.