What are the associated cardiac anomalies with infracristal Ventricular Septal Defect (VSD)?

Associated Anomalies of Infracristal VSD

Infracristal (perimembranous) VSDs are commonly associated with aortic valve abnormalities, particularly aortic regurgitation from valve prolapse, as well as left ventricular outflow tract obstruction, patent ductus arteriosus, coarctation of the aorta, and atrial septal defects. 1

Primary Associated Cardiac Anomalies

Aortic Valve Complications

• Aortic valve prolapse occurs in 3.6% of patients with VSD overall, with the highest risk in supracristal defects, but perimembranous (infracristal) VSDs also develop this complication 2
• Aortic regurgitation develops in 7.6% of adult patients with VSD, with most cases detected before age 30 years, making serial surveillance essential 2
• The mechanism involves progressive prolapse of the aortic valve leaflet (typically the right coronary cusp) into the VSD, leading to valvular incompetence 1, 3

Left Ventricular Outflow Tract Obstruction

• Discrete subaortic stenosis can develop even after spontaneous VSD closure, particularly in patients with small or closed perimembranous defects 4
• Infundibular pulmonary stenosis occurs in 5.8% of VSD patients, representing the most common associated structural abnormality after aortic valve disease 2
• Serial echocardiographic evaluation of the LVOT is mandatory in patients with small or closed VSDs who retain a significant murmur or ECG abnormalities 4

Extracardiac Vascular Anomalies

• Patent ductus arteriosus coexists in 1.9% of VSD patients and requires specific management considerations 2
• Coarctation of the aorta occurs in 1.5% of cases, often as part of left-sided obstructive lesion spectrum 2, 5
• When PDA and coarctation coexist with VSD, closure of the PDA is indicated if there is left ventricular volume overload or pulmonary hypertension 6

Other Intracardiac Defects

• Ostium secundum atrial septal defect is present in 2.2% of VSD patients 2
• Pulmonary valve stenosis occurs in 2.7% of cases 2
• Mitral valve abnormalities, including regurgitation, can complicate infracristal VSDs requiring valve repair or replacement 3

Clinical Implications and Surveillance Strategy

Progressive Lesions Requiring Monitoring

• 22% of patients with congenital VSD have significant associated cardiac abnormalities, many of which develop or progress over time 2
• Aortic prolapse and regurgitation may develop subsequently and should be actively sought during initial assessment and monitored during follow-up 2
• Follow-up to age 30 years allows detection of most cases of aortic regurgitation that will develop 2

Surgical Considerations for Infracristal VSDs

• Large infracristal VSDs in adults carry higher mortality risk compared to supracristal defects, particularly when associated with pulmonary hypertension and irreversible pulmonary vascular changes 3
• Complete heart block is a significant risk after surgical repair of perimembranous VSDs because the His bundle typically passes along the rim of the defect 1
• In addition to VSD closure, concomitant procedures may include aortic valve replacement, mitral valve repair, or repair of sinus of Valsalva fistula 3

Complexity Classification

• VSDs with associated abnormalities are classified as moderate complexity by both AHA/ACC and ESC guidelines, requiring specialized follow-up 1
• Isolated small VSDs are classified as simple (mild complexity), but the presence of associated lesions or moderate/greater shunt elevates the classification 1

Common Pitfalls to Avoid

• Do not assume a closed or small VSD requires no further follow-up—discrete subaortic stenosis can develop years after VSD closure 4
• Avoid missing progressive aortic regurgitation by ensuring serial echocardiographic assessment through at least age 30 years 2
• Do not rely solely on calculated shunt flow to predict outcomes in large infracristal VSDs with pulmonary hypertension, as irreversible pulmonary vascular changes may not be anticipated by hemodynamic measurements alone 3
• Recognize that percutaneous closure of perimembranous VSDs carries significant risk of complete heart block and is not recommended despite technical feasibility 7