Common Adult Congenital Lesions

Patent Ductus Arteriosus (PDA)

The ductus arteriosus is a fetal vessel connecting the proximal descending aorta to the main pulmonary artery (near the origin of the left branch), which normally closes functionally within the first day or two of life and anatomically within weeks. A persistent PDA in an adult continues to shunt because aortic pressure exceeds pulmonary artery pressure throughout essentially the entire cardiac cycle -- systole and diastole -- producing the defect's signature continuous flow pattern on spectral Doppler in the main pulmonary artery, correlating with the classic continuous "machinery" murmur on auscultation. Color Doppler shows a high-velocity, turbulent jet entering the main PA near the bifurcation. A large, long-standing PDA volume-loads the left atrium and left ventricle (not the right heart), since the shunted blood recirculates through the pulmonary veins into the LA.

Bicuspid Aortic Valve (BAV)

Bicuspid aortic valve is the most common congenital heart defect, present in roughly 1-2% of the general population. It results from failure of separation between two of the three normal aortic cusps during valvulogenesis, producing a fibrous fusion ridge called a raphe; fusion of the right and left coronary cusps is the most frequent pattern. On parasternal short-axis imaging at the valve level, the normal tri-leaflet "Mercedes-Benz" sign is replaced by an eccentric, two-commissure, "fish-mouth" orifice.

BAV carries two distinct long-term risks that must both be screened for:

• Valve dysfunction: accelerated leaflet degeneration leads to earlier-onset aortic stenosis and/or regurgitation than in a normal trileaflet valve, and elevated endocarditis risk.
• Aortopathy: an intrinsic connective-tissue abnormality of the aortic wall causes ascending aortic (and root) dilation/aneurysm that is independent of the valve's hemodynamic severity -- a well-functioning bicuspid valve can still sit atop a significantly dilated ascending aorta, so the ascending aorta must be measured on every study regardless of valve gradient.

BAV is also strongly associated with coarctation of the aorta, and the two lesions should be actively sought together.

Coarctation of the Aorta

Coarctation is a discrete narrowing of the aorta, classically located at the aortic isthmus just distal to the origin of the left subclavian artery, at the site of the ligamentum arteriosum. It is best interrogated from the suprasternal notch view, where the arch and proximal descending aorta can be aligned with the Doppler beam. The hallmark spectral Doppler finding is a "sawtooth" pattern of persistent antegrade diastolic flow (diastolic runoff) in the descending aorta -- because the pressure gradient across the coarctation persists throughout diastole, unlike normal aortic flow, which returns to baseline. Coarctation is frequently associated with bicuspid aortic valve and with Turner syndrome, and clinically presents with upper-extremity hypertension and diminished or delayed femoral pulses (an arm-to-leg blood pressure gradient).

Ebstein Anomaly

Ebstein anomaly is a malformation of the tricuspid valve in which the septal and (often) posterior leaflets fail to delaminate normally from the underlying myocardium, resulting in apical (downward) displacement of their attachment into the right ventricle. This displacement "atrializes" the inlet portion of the RV, leaving a functionally small, distal true RV. The anterior leaflet is typically elongated, redundant, and described as "sail-like."

Because roughly half of patients have an associated interatrial communication, right-to-left shunting and cyanosis can occur, especially with elevated RA pressure from a severely regurgitant, atrialized right heart.

Patent Foramen Ovale (PFO)

A PFO is a flap-valve remnant of incomplete fusion between the septum primum and septum secundum, present as a normal anatomic variant in roughly one-quarter of the general population. Because resting LA pressure normally exceeds RA pressure, the flap stays functionally closed and no shunt is seen at rest. A PFO is detected using the agitated-saline bubble study with a release-phase Valsalva maneuver described in the previous section; the clinical concern is paradoxical embolism as a mechanism of cryptogenic stroke.

Repaired Tetralogy of Fallot: Residual Pulmonary Regurgitation

Classic tetralogy of Fallot combines a VSD, an overriding aorta, right ventricular outflow tract (RVOT) obstruction, and RV hypertrophy. Surgical repair closes the VSD and relieves the RVOT obstruction, frequently using a transannular patch that widens the pulmonic annulus -- but this repair sacrifices pulmonic valve competence. As a result, chronic, often severe, pulmonary regurgitation (PR) is the dominant long-term residual lesion in repaired TOF patients, not a residual VSD or residual obstruction. Chronic PR volume-overloads the RV, driving progressive RV dilation and eventual dysfunction over years to decades. Serial echocardiographic (or cardiac MRI) assessment of RV size and function is used to time pulmonary valve replacement before irreversible RV dysfunction develops. Other residua to actively screen for on follow-up studies include branch pulmonary artery stenosis, a residual VSD patch leak, RVOT aneurysm, and arrhythmia substrate. Because PR jets are often low-velocity and hard to grade by color jet width alone in a large, dilated RVOT, adjunct signs -- diastolic flow reversal in the branch pulmonary arteries, a short pulmonary regurgitant jet deceleration time (pressure equilibration), and serial RV volumes -- are used together to judge severity and timing for reintervention.