ASD, VSD, and PDA Device Closure: Devices, Deployment, and Defect Sizing

Overview

1. Atrial Septal Defect (ASD) Closure

What is an ASD?

• Secundum ASD — most common, located in the fossa ovalis region ✅ ideal for transcatheter
• Patent Foramen Ovale (PFO) — transcatheter closure FDA-approved for cryptogenic stroke ✅
• Superior sinus venosus ASD — now treated with covered stent in SVC-RA junction
• Primum ASD / Inlet ASD — not amenable; require surgical repair

ASD Closure Devices

Step-by-step echocardiographic/diagrammatic view of ASD device deployment including balloon-assisted technique

ASD Sizing — Critical Steps

• TEE or TTE measures the ASD diameter in multiple planes (bicaval view, short-axis view, 4-chamber view)
• 3D echocardiography provides the best spatial assessment of defect shape and rim adequacy
• Rim assessment is essential: a rim <5 mm ("deficient rim") — especially the retro-aortic rim — complicates device placement and increases erosion risk with the ASO

• A compliant sizing balloon (e.g., NuMed Sizing Balloon) is advanced across the ASD via the delivery sheath
• The balloon is inflated with dilute contrast under TEE/fluoroscopic guidance
• Inflation continues until the left-to-right shunt stops completely (stop-flow endpoint) — verified by color Doppler
• The stretched diameter of the balloon at this exact point is measured fluoroscopically
• ⚠️ Do NOT overinflate beyond cessation of shunt — overinflation overstates the true defect size and risks erosion

Panel (a): balloon sized at 18.5 mm. Panel (b): device crossing the septum. Panel (c): 20 mm Amplatzer fully deployed.

• ASO: Choose device = same size as stop-flow diameter, or at most 1 size larger
• Maximum: Device ≤ 1.5× the echocardiographic (static) ASD diameter — never exceed this to avoid erosion
• Deficient retro-aortic rim (<5 mm): Higher erosion risk with ASO. Consider GORE Cardioform (no erosion reported) or specialized techniques

ASD Deployment Steps (Amplatzer ASO Technique)

1. Venous access via right femoral vein
2. Transseptal puncture (if not crossing through defect directly)
3. Position TorqVue long sheath in left upper pulmonary vein (stable position)
4. Size the defect (balloon stop-flow technique as above)
5. Load the device into loader, connect to delivery cable (screwthread mechanism)
6. Advance device through sheath into left atrium
7. Open LA disc in left atrium, pull back to engage the septum
8. Retract sheath to open RA disc in right atrium
9. Perform "wiggle test" — push-pull maneuver under TEE/fluoroscopy to confirm stability
10. Assess position: device must not impinge on SVC, pulmonary veins, mitral valve, or aorta
11. If position stable → release device by counterclockwise rotation of delivery cable
12. Confirm closure with color Doppler TEE

Left: balloon sizing measuring 11.88 mm. Right: GORE Cardioform fully deployed across the septum.

2. Ventricular Septal Defect (VSD) Closure

What is a VSD?

VSD Closure Devices

VSD Sizing and Deployment

• 2D/3D TEE in multiple views: RV inflow-outflow, parasternal short axis, apical 4-chamber
• Measure the defect diameter directly — balloon sizing not routinely needed for most VSDs (unlike ASD)
• Device size selected to be 1–2 mm larger than the measured defect
• Confirm adequate rim from aortic valve, TV, and MV

1. Femoral venous + arterial access
2. Cross the VSD from the LV side (arterial, retrograde) with a wire
3. Establish arteriovenous wire loop (snared from RV and exteriorized via femoral vein)
4. Advance long delivery sheath from femoral vein, crossing VSD into LV
5. Open LV disc in left ventricle
6. Pull back to appose the septum
7. Open RV disc in right ventricle
8. Wiggle test, TEE confirmation of position
9. Ensure no AV valve impingement, no aortic regurgitation
10. Release device

• Complete AV block (most feared — perimembranous VSDs)
• Aortic regurgitation (from device impinging on aortic valve)
• Tricuspid regurgitation
• Device embolization

3. Patent Ductus Arteriosus (PDA) Closure

What is a PDA?

PDA Closure Devices

Left to right: ADO-I (funnel-shaped plug), ADO-II (symmetric skirts), Amplatzer Vascular Plug II, Nit-Occlud coil, deployment fluoroscopy

PDA Sizing and Deployment

• Angiography (aortogram in lateral projection) is the gold standard: measures minimum PDA diameter, length, and shape (Type A–E Krichenko classification)
• TTE/TEE supplementary: measures minimum diameter, LPA/aortic end diameter
• Device size selected: ≥1–2 mm larger than the narrowest (minimum) PDA diameter
• For ADO-I: device diameter at pulmonary end should match the PDA minimum diameter +1–2 mm; the retention disc sits in the aortic ampulla

1. Right femoral venous access; advance catheter across PDA from PA to descending aorta
2. Establish guidewire in descending aorta
3. Advance long delivery sheath into descending aorta
4. Screw device onto delivery cable clockwise; load into sheath
5. Advance device into descending aorta → retract sheath to open retention disc in aortic ampulla
6. Pull sheath + cable back as one unit until retention disc is snug at aortic end of ampulla
7. Retract sheath further into PA → tubular body and PA disc open within the duct
8. Confirm position angiographically (no LPA or aortic obstruction) and by echocardiography
9. Check for residual shunting with color Doppler
10. Release device (counterclockwise rotation)

Summary: Sizing Rules at a Glance

Imaging Guidance During All Procedures