Atrial Septal Defect

Definition

Atrial septal defect (ASD) is a direct communication between the left and right atria, resulting in a left-to-right shunt whose magnitude depends on defect size and relative ventricular compliance. (sources/asd-ehj-2022 — high; sources/asd-lancet-2014 — high)

Key Concepts

Epidemiology

• Incidence ~56–100/100,000 livebirths; third most common type of CHD overall (sources/asd-ehj-2022 — high; sources/asd-lancet-2014 — high)
• Most common CHD diagnosed in adulthood (25–30% of new adult CHD diagnoses), owing to slow clinical progression and frequent asymptomatic presentation in early life (sources/asd-ehj-2022 — high)
• Sex distribution by subtype: ~65–70% of secundum, ~50% of primum, ~40–50% of sinus venosus defects are female (sources/asd-lancet-2014 — high)

Anatomy and Classification

• Secundum ASD (80%): Fossa ovalis; most amenable to percutaneous device closure (sources/asd-ehj-2022 — high)
• Primum ASD / Partial AVSD (15%): Adjacent to AV valves; near-always abnormal AV valve morphology; surgical repair required; more prone to AV block and AV valve regurgitation (sources/asd-ehj-2022 — high)
• Sinus venosus ASD: Superior type (~5%) at SVC–right atrium junction with frequent partial anomalous pulmonary venous drainage (PAPVD); inferior type (<1%) at IVC junction; predominantly surgical but covered stent catheter technique emerging for superior type (sources/asd-ehj-2022 — high)
• Coronary sinus defect (rarest): Unroofing between coronary sinus and left atrium; strongly associated with persistent left SVC (Raghib syndrome) (sources/asd-ehj-2022 — high)
• Common atrium (very rare): Absent septum primum + septum secundum + AV canal septum; often associated with heterotaxy syndrome (sources/asd-lancet-2014 — high)
• Distinguished from PFO: PFO is not a true deficiency of atrial septal tissue (tunnel communication); complete anatomical closure occurs in 70–75% of adults; does not require closure for ASD indications (sources/asd-ehj-2022 — high; sources/asd-lancet-2014 — high)
• The distinction is not academic — the two lesions have different closure indications and different evidence. An ASD is closed for shunt-related right-heart volume loading; a PFO is closed for secondary prevention of paradoxical stroke after a cryptogenic event, and only in a selected population. A PFO that is small and not shunting needs no closure at all; an ASD of any size that produces right ventricular enlargement does. (sources/pfo-eso-2024, rating: very high) See concepts/Patent-Foramen-Ovale.
• Atrial septal aneurysm is a PFO-associated finding, not an ASD feature — defined as ≥10 mm excursion of the septum primum from the plane of the atrial septum, and one of the two anatomical criteria that identify PFO patients with the largest treatment effect from closure. (sources/pfo-jama-2025, rating: high)

Genetics and Aetiology

• Most sporadic; genetic syndromes: Down (~80%), Holt-Oram (66% have ASD), Ellis van Creveld (~60%), Noonan (~20%) (sources/asd-ehj-2022 — high; sources/asd-lancet-2014 — high)
• Implicated genes: NKX2-5 (also linked to AV block), GATA4, TBX5, MYH6 (chromosome 14q12) (sources/asd-ehj-2022 — high; sources/asd-lancet-2014 — high)
• Maternal exposures: alcohol, smoking, SSRIs/antidepressants, diabetes, high dietary glycaemic index, advanced maternal age ≥35 years (sources/asd-ehj-2022 — high; sources/asd-lancet-2014 — high)

Pathophysiology

• Left-to-right shunt → right atrial and RV volume overload → RV dilatation, myocardial stretch, increased pulmonary blood flow
• Shear stress on pulmonary endothelium → activation of growth factors, vasoconstrictors, smooth muscle hypertrophy → PAH (pulmonary vascular disease relatively rare, but risk increases with age and large defects)
• LV volume unloading and adverse ventricular–ventricular interaction also occur (not purely a right-heart lesion) (sources/asd-ehj-2022 — high)
• As LV stiffens with age (hypertension/CAD), degree of L→R shunting increases further (sources/asd-ehj-2022 — high)

Natural History

• Life expectancy without closure (Campbell, untreated large secundum): annualised mortality 0.6–0.7%/yr in first two decades; rising to 4.5%/yr in 4th decade; 7.5%/yr in 6th decade (sources/asd-lancet-2014 — high)
• Sinus venosus and primum defects do not decrease in size; almost always require surgical closure (sources/asd-lancet-2014 — high)
• Secundum spontaneous closure rates (Hanslik 2006, n=200, median age 5 months):
  • 4–5 mm: 56% spontaneous closure
  • 6–7 mm: 30% spontaneous closure
  • 8–10 mm: 12% spontaneous closure

  • 10 mm: 0% spontaneous closure

• Change in defect size over time: initially ≤4 mm → 70% decrease; initially >8–12 mm → 76% increase (sources/asd-lancet-2014 — high)
• Cardiac remodelling after closure: Begins immediately but continues ≥1 year; extent of RV reverse remodelling inversely related to age at closure (sources/asd-ehj-2022 — high)
• RVESVI >75 mL/m² at closure → persistent RV dilatation, residual TR, elevated BNP, RV dysfunction (sources/asd-ehj-2022 — high)
• Long-term survival after surgery vs general population (Murphy, 27–32 year follow-up):
  • Operated <12 yr: 98% vs 99% (near-normal)
  • Operated 12–24 yr: 93% vs 97%
  • Operated 25–41 yr: 84% vs 91%
  • Operated >41 yr: 40% vs 59% (sources/asd-lancet-2014 — high)

Diagnosis

• First-line: TTE (2D + colour Doppler); RV enlargement with normal/hyperdynamic function = haemodynamically significant ASD
• TOE: Near-universally performed after TTE; essential for sinus venosus defects, suboptimal TTE windows, intraprocedural guidance
• 3D echocardiography: Defect characterisation, rim assessment, device sizing
• CMR: Gold standard for ventricular volumes and Qp/Qs measurement; indispensable for inferior sinus venosus defects and when echocardiography leaves unanswered questions; non-invasive gold standard for absolute Qp and Qs measurement — see concepts/Intracardiac-Shunts
• Transpulmonary ultrasound dilution (COstatus): In critically ill or surgical paediatric patients who cannot undergo MRI, this minimally invasive bedside method estimates Qp/Qs via dilution curve asymmetry using existing arterial + central venous catheters; sensitivity 95.7%, specificity 97.6% for L→R shunt detection, but underestimates Qp/Qs magnitude in moderate/small shunts (sources/shunt-nature-sr-2020 — medium); see concepts/Intracardiac-Shunts
• Cardiac CT: High-resolution anatomy at <1 mSv; when echocardiography or CMR insufficient
• Cardiac catheterisation: NOT routine; mandatory when PH suspected (sPAP estimate >40 mmHg), LV dysfunction, or CAD evaluation needed (sources/asd-ehj-2022 — high)
• Qp:Qs — limitations of a relative metric:
  • Qp:Qs ≥1.5:1 is the standard criterion for haemodynamically significant ASD; influenced by defect size and ventricular compliance (sources/asd-ehj-2022 — high)
  • Critical limitation: Qp:Qs is a relative index — does not capture absolute pulmonary blood volume, which may be the more pathophysiologically relevant metric (sources/asd-japc-2025 — medium)
  • Illustrative example: Two patients both with Qp:Qs 1.8:1 but resting cardiac outputs of 4 L/min and 6 L/min have pulmonary flows of 7.2 L/min vs 10.8 L/min — a 50% difference in volume overload burden (sources/asd-japc-2025 — medium)
  • A tall, athletic individual with hyperdynamic circulation may carry a substantially higher right heart burden at the same Qp:Qs as a sedentary patient
  • Qp:Qs assumes stable vascular resistances; does not account for physiological fluctuations during exercise or neurohumoral modulation (sources/asd-japc-2025 — medium)

Management

Indications for Closure

• General principle: Timely closure in presence of RV volume overload irrespective of age (excluding advanced pulmonary vascular disease or significant LV impairment); multidisciplinary CHD team decision (sources/asd-ehj-2022 — high)
• Optimal age: Before 25 yr → normal survival; benefits observed at all ages
• PVR thresholds (invasive haemodynamic assessment mandatory when PH present):
  • PVR <5 WU: closure safe and beneficial
  • PVR ≥5 WU: closure likely harmful → initiate PAH pharmacotherapy first; reassess
  • PVR ≥5 WU + Qp/Qs >1.5 on PAH therapy: fenestrated closure may be considered (long-term evidence lacking)
  • PVR ≥5 WU despite PAH treatment: closure contraindicated
• Vasoreactivity testing with inhaled NO: NOT recommended in ASD-PAH decision-making (sources/asd-ehj-2022 — high)
• LV impairment: balloon test occlusion pre-device deployment; pre-conditioning with HF medical therapy (sources/asd-ehj-2022 — high)

Percutaneous (Catheter) Closure

• Treatment of choice for eligible secundum ASDs (>80% of all ASDs); low complication rate vs surgery; no sternotomy; shorter stay (sources/asd-ehj-2022 — high)
• Anatomic contraindications: insufficient/absent rims (except isolated absent aortic rim which can often be accommodated), very large defect (>36–40 mm), excessively floppy aneurysm; interference with AV valves or venous drainage (sources/asd-lancet-2014 — high)
• Devices: self-centring Amplatzer-type shape memory alloy occluders; ASO (St. Jude Medical) can close defects up to 38 mm; biodegradable devices in development (sources/asd-closure-jc-2015 — high)
• Device complication rates (meta-analysis, 28,142 patients, 203 studies):
  • Major periprocedural: 1.6% (95% CI 1.4–1.8); device embolisation 0.7%; pericardial tamponade 0.1%
  • Late complications: arrhythmias 1.5%, stroke 0.4%, device thrombosis 0.2%, cardiac erosion 0.1%, embolisation 0.1%, death 0.1% (sources/asd-lancet-2014 — high)
• Nickel allergy: new-onset/worsening migraine reported; clopidogrel may help (sources/asd-lancet-2014 — high)
• Antiplatelet drugs routinely prescribed post-device but supporting data lacking (sources/asd-lancet-2014 — high)
• Emerging: covered stent for superior sinus venosus ASD (catheter); still requires surgical backup (sources/asd-ehj-2022 — high)

Cardiac Erosion — Mechanism and Risk Factors

• Rare (<0.1%) but serious complication; complete mechanism not established (sources/asd-lancet-2014 — high; sources/asd-closure-jc-2015 — high)
• Established risk factors: aortic (superoanterior) rim deficiency + oversized device selection (sources/asd-closure-jc-2015 — high)
• Atrial septal malalignment (novel risk factor): Surfaces of septum primum and secundum are vertically offset, causing tight impingement of the right atrial disk toward the aortic root; changes the device axis angle after cable release → increased erosion risk. Many patients with aortic rim deficiency do NOT erode — malalignment likely the additional required factor (sources/asd-closure-jc-2015 — high)
• Updated ASO Instructions for Use (IFU): IVC rim <5 mm added as contraindication (in addition to existing aortic rim deficiency criterion), because this anatomy tends to cause oversized device selection (sources/asd-closure-jc-2015 — high)
• Pre-deployment assessment of malalignment is difficult; both disk surfaces must be observed pre- and post-cable release
• Longitudinal follow-up is essential — late erosion has been documented

Technical Techniques for Difficult ASD

• Large ASD (>30 mm) and wide rim deficiency require modified techniques; operators should master 1–2 alternatives (sources/asd-closure-jc-2015 — high)
• LUPV/RUPV (pulmonary vein) technique: Left atrial disk deployed inside left or right upper pulmonary vein, then retracted to optimal septal position; enables large devices up to 38 mm; pulmonary vein injury is a concern
• Hausdorf sheath (Cook, Bloomington, IN): Designed to align left atrial disk parallel to atrial septum; improves approach in large defects
• Balloon assist technique: Partially inflated Amplatzer sizing balloon holds left atrial disk inside left atrium, preventing prolapse into right atrium; relatively simple, requires additional venous access; high success rates even for large ASD
• Sheath rotation/remolding: Rotation or remolding outside the body to improve alignment at the interatrial septum
• Straight side-hole delivery sheath (Kutty): Enhanced delivery in difficult anatomy

Hemodynamic Management in Elderly Patients

• ~10% of transcatheter ASD cases may be aged >70 years; majority have ≥1 major comorbidity; most are NYHA class >II (sources/asd-closure-jc-2015 — high)
• LV diastolic dysfunction is masked by the L→R shunt (unloads LV); closure causes abrupt LV preload rise → risk of acute CHF, especially in elderly with impaired diastolic function (sources/asd-closure-jc-2015 — high)
• Pre- and peri-procedural anti-congestive therapy (diuretics, optimised fluid balance): essential to prevent post-closure CHF in elderly; series shows no acute CHF despite impaired diastolic function when pre-treated (sources/asd-closure-jc-2015 — high)
• PCWP monitoring protocol (author's institution): (sources/asd-closure-jc-2015 — high)
  • PCWP continuously monitored during device deployment
  • Abandon procedure if mean PCWP rises >10 mmHg from baseline during test balloon occlusion
  • Abandon procedure if mean PCWP >20 mmHg absolute (pulmonary oedema risk)
• Fenestrated device: May moderate abrupt hemodynamic change post-closure; optimal fenestration size not yet evaluated; limited evidence (sources/asd-closure-jc-2015 — high)
• Balloon test occlusion pre-device deployment is recommended when LV dysfunction is suspected (sources/asd-ehj-2022 — high; sources/asd-closure-jc-2015 — high)

Surgical Closure

• Indicated for sinus venosus, primum, coronary sinus defects, and secundum not amenable to device closure
• Mortality <1%; major complications <7%; most common complication: postoperative arrhythmia
• Minimally invasive approaches (mini-sternotomy, thoracotomy, robotics) comparable outcomes to sternotomy (sources/asd-ehj-2022 — high)

Arrhythmia Management

• Atrial flutter and AF prevalence increases steeply with age: >20% atrial flutter, >50% AF by age 60 (sources/asd-ehj-2022 — high)
• AF prevalence by decade: ~1/3 of patients aged >60 years; ~1/2 of patients aged >70 years have AF (sources/asd-closure-jc-2015 — high)
• Substrate: right atrial fibrosis, reduced voltage, prolonged refractory periods, Bachmann's bundle conduction disturbances (sources/asd-ehj-2022 — high)
• ASD closure does NOT reliably reduce AF burden (meta-analysis of 25 studies: percutaneous closure not associated with arrhythmia reduction) (sources/asd-ehj-2022 — high)
• Closure before age 40 may offer some AF protection; persistent AF unlikely to benefit; paroxysmal AF may improve at lower ages (sources/asd-ehj-2022 — high)
• Key management principle — PVI before ASD closure when symptomatic AF present (freedom from post-closure AF 79% vs 37%); closing ASD first increases complexity of trans-septal access (sources/asd-ehj-2022 — high)
• PVI-first criteria (Okayama University protocol): age <75 years + symptomatic paroxysmal or persistent AF + LA dimension <50 mm; ASD closure scheduled when sinus rhythm persists >3 months after ablation (sources/asd-closure-jc-2015 — high)
• Ablation after percutaneous closure is feasible when the sequence is reversed. Pooled analysis of three single-arm series (64 patients, follow-up 6–22 months): transseptal puncture succeeded in 100%, with 18.75% puncturing through the device and the remainder through native septum, all but one under fluoroscopic plus intracardiac echocardiographic guidance. Freedom from AF was 77.7% (95% CI 65.7–86.3), with no device dislodgement, no residual shunt and no device deformation. Puncture through the device lengthened total procedure time (237.3 versus 180 min, P=0.004) without changing recurrence (23.07% versus 16.66%; RR 1.18, 0.35–4.00), and was associated with a 4.7% inadvertent epicardial puncture rate even in high-volume centres. Pooled observation supports safety at least 6 months after implantation, but this is 64 patients across three uncontrolled series and does not overturn the case for ablating before closure where ablation is already planned. (sources/af-ablation-asd-device-jce-2020 — medium)
• Permanent AF: NOT a contraindication to ASD closure; closure resolves L→R shunt and improves symptoms; strict anticoagulation required indefinitely post-closure (sources/asd-closure-jc-2015 — high)
• Sinus node dysfunction: more prevalent in superior sinus venosus defects (sources/asd-ehj-2022 — high)
• AV block: more frequent in primum ASDs (inferiorly displaced AV conduction system) (sources/asd-ehj-2022 — high)

PAH Management

• Oral ERA ± PDE5 inhibitor when PVR ≥5 WU (sources/asd-ehj-2022 — high)
• Eisenmenger syndrome: proactive PAH therapy with prostacyclins; subcutaneous/inhaled preferred over parenteral (sources/asd-ehj-2022 — high)
• Closure contraindicated in established Eisenmenger syndrome (sources/asd-ehj-2022 — high)

Exercise Physiology and Shunt Dynamics

• Left atrial pressure rises more than right atrial pressure during exercise; the left atrium is described as stiffer in ASD patients (sources/asd-japc-2025 — medium)
• Exercise-induced changes in right and left atrial compliance, PVR-compliance, and systemic arterial pressure could dynamically alter trans-atrial pressure gradients and shunt volume
• The assumption that Qp:Qs remains stable at rest and during exercise is largely unvalidated (sources/asd-japc-2025 — medium)
• Three published studies with contradictory findings on exercise shunt response:
  • Bay et al. 1971 (stress testing): increased absolute shunt volume
  • Nielsen & Fabricius 1968 (exercise): decreased shunt volume
  • Stephensen et al. 2017 (dobutamine + atropine stress, CMR): no change in shunt volume
  • Caveats: very small sample sizes; some used pharmacological rather than true exercise stressors; individual responses within each study contradicted average trends (sources/asd-japc-2025 — medium)
• Key conceptual point: A declining Qp:Qs during exercise does NOT necessarily indicate reduced absolute pulmonary flow — if systemic cardiac output rises faster than the ratio falls, net pulmonary flow may still increase
• Endurance exercise in unrepaired ASD may exacerbate right heart dilation and trigger maladaptive pulmonary vascular remodeling in susceptible individuals; current guidelines provide no clear directive on exercise restriction (sources/asd-japc-2025 — medium)
• Advanced characterisation tools: real-time 4D flow MRI; invasive exercise hemodynamics — not in routine clinical use

Post-Closure Outcomes

Stroke

• Open ASD: ~4% stroke prevalence (paradoxical embolism primary mechanism) (sources/asd-ehj-2022 — high)
• Closed ASD: 1.4% stroke prevalence (residual risk from AF and pulmonary venous remodelling) (sources/asd-ehj-2022 — high)
• Consider anticoagulation 6–12 months post-closure in older patients irrespective of pre-procedural AF (sources/asd-ehj-2022 — high)

Predictors of Late-Onset PAH After Closure

• The belief that ASD closure reduces pulmonary pressures in all patients is overly simplistic (sources/asd-japc-2025 — medium)
• A subset of patients develops PAH before or even after closure; late-onset PAH can occur years to decades post-intervention — an increasingly recognised phenomenon (sources/asd-japc-2025 — medium)
• Risk factors for post-closure PAH:
  • Delayed closure (typically >40 yr) — irreversible pulmonary vascular changes may have occurred before repair
  • Pre-closure elevated PVR even if below Eisenmenger threshold; pre-closure hemodynamic assessment including vasoreactivity testing and PVR quantification is essential in older adults and symptomatic patients
  • BMPR2 genetic variants — limited data in ASD-specific cohorts; data extrapolated from IPAH/HPAH literature (sources/asd-japc-2025 — medium)
  • Unrecognised pulmonary microvascular disease, especially in women or patients with autoimmune conditions
• Some patients develop PAH despite early closure — suggesting nonhemodynamic mechanisms: endothelial dysfunction, inflammation, in situ thrombosis (sources/asd-japc-2025 — medium)
• An abnormal rise in pulmonary arterial pressure in response to augmented blood flow (exercise or medication) — before or after closure — may help identify patients at higher PAH risk (sources/asd-japc-2025 — medium)

Pregnancy

• Well tolerated in uncomplicated ASD; advise closure before conception (sources/asd-ehj-2022 — high)
• ASD discovered during pregnancy: continue, close electively post-partum (sources/asd-ehj-2022 — high)
• Repaired ASD: pregnancy outcomes equivalent to general population (sources/asd-ehj-2022 — high)
• ASD + PAH: pregnancy risks prohibitive; effective contraception essential (sources/asd-ehj-2022 — high)

Contradictions / Open Questions

• ASD and PFO closure share a procedure but not an evidence base. Device closure of a secundum ASD is justified by haemodynamic load and has decades of follow-up; device closure of a PFO is justified by a ~2% absolute reduction in recurrent stroke at two years and has no data beyond five. Both use double-disc occluders, both cause device-related atrial fibrillation, and the two populations are frequently conflated in referral — a patient sent for "ASD/PFO closure" may have either indication, and only one of them is supported by the numbers in their chart. (sources/pfo-eso-2024, rating: very high)
• PVR threshold for ASD closure — 5 WU vs 8 WU: Brida et al. EHJ 2022 cites PVR ≥5 WU as contraindication to closure (per ESC 2020 guidelines); Geva et al. Lancet 2014 cites PVR >8 WU as generally precluding closure (per ACC/AHA 2008 and ESC 2010). The 5 WU threshold represents the more recent and current standard. Clinically significant: a patient with PVR 6–7 WU would be refused closure under ESC 2020 but potentially acceptable under older guidelines. (sources/asd-ehj-2022 — high; sources/asd-lancet-2014 — high)
• ASD closure and AF — short-term benefit but long-term attenuation: Geva 2014 Lancet meta-analysis (26 studies, 1841 surgical + 945 transcatheter) shows OR 0.66 reduction in arrhythmias short-term, but beneficial effect lost at ≥5 years follow-up. Brida 2022 EHJ meta-analysis (25 studies) shows percutaneous closure NOT associated with arrhythmia reduction overall. Both support that ASD closure is not an indication for closure based on AF alone. (sources/asd-ehj-2022 — high; sources/asd-lancet-2014 — high)
• Treat-and-repair strategy in ASD-PAH: Long-term benefit of PAH pharmacotherapy followed by closure (treat-and-repair) is unproven. Evidence for benefit is limited and quality is low. (sources/asd-ehj-2022 — high)
• Prophylactic catheter ablation before ASD closure in patients without documented AF: Whether to ablate prophylactically, and whether targeting Bachmann's bundle improves arrhythmia-free survival, remains unresolved. (sources/asd-ehj-2022 — high)
• Fenestrated closure in borderline PVR (≥5 WU + Qp/Qs >1.5): Long-term impact of fenestrated vs complete closure in this subgroup is unknown. (sources/asd-ehj-2022 — high)
• Sinus venosus defect catheter closure: Covered stent approach is promising but data are very limited (small series); remains investigational with surgical closure as standard of care. (sources/asd-ehj-2022 — high)
• No RCT comparing transcatheter vs surgical closure: As of Lancet 2014 and still relevant — comparative effectiveness relies on observational and registry data only. (sources/asd-lancet-2014 — high)
• PVR threshold units — indexed vs absolute: Akagi 2015 JC cites hemodynamic criterion as PVR <5 WU/m² (indexed to BSA); EHJ 2022 and ESC 2020 guidelines use absolute PVR <5 WU. For an average adult (BSA ~1.7–1.9 m²), indexed PVR <5 WU/m² corresponds to absolute PVR ~3.0–3.5 WU — a meaningfully stricter criterion. A patient with absolute PVR 4 WU would be eligible under ESC guidelines but potentially borderline under the indexed criterion. Clinical practice should clarify which metric is being used. (sources/asd-closure-jc-2015 — high; sources/asd-ehj-2022 — high)
• Cardiac erosion mechanism — incomplete: The definite mechanism is not established. Aortic rim deficiency + oversized device are accepted risk factors, but most cases with these features do NOT erode. Atrial septal malalignment has been proposed as an additional required factor but evidence is mechanistic/case-series level, not prospective. (sources/asd-closure-jc-2015 — high)
• Qp:Qs ratio — relative metric masking absolute flow burden: Qp:Qs does not capture absolute pulmonary blood volume. Two patients with identical Qp:Qs 1.8:1 can differ by >3 L/min in absolute pulmonary flow. Clinical decision thresholds (e.g., Qp:Qs ≥1.5) may underappreciate hemodynamic burden in individuals with high cardiac output (athletes, hyperdynamic states). No validated absolute flow threshold has been proposed. (sources/asd-japc-2025 — medium)
• Exercise-induced shunt dynamics — unresolved and contradictory: Three published studies show opposing directions of change in absolute shunt volume during exercise (Bay 1971: increased; Nielsen 1968: decreased; Stephensen 2017: no change). None used invasive exercise hemodynamics or 4D flow MRI with adequate sample sizes. True impact of exercise on ASD physiology across the age spectrum remains unclear. (sources/asd-japc-2025 — medium)
• Exercise restriction in unrepaired ASD — no guideline guidance: Whether patients with unrepaired ASD — particularly those engaged in endurance sports — should limit physical activity to prevent right heart volume overload and pulmonary vascular remodeling is unanswered. Current guidelines contain no specific directive. (sources/asd-japc-2025 — medium)
• Post-closure PAH risk stratification — no validated model: Late-onset PAH after ASD closure is recognised but not reliably predictable. Candidate risk factors (delayed closure >40 yr, pre-closure elevated PVR, BMPR2 variants, pulmonary microvascular disease) are hypothesis-generating only; no prospective validated risk stratification tool exists. (sources/asd-japc-2025 — medium)
• BMPR2 variants in ASD-associated PAH — limited data: BMPR2 is established in IPAH/HPAH, but evidence for its role in ASD-associated PAH specifically is described as "limited" with no quantification. Genetic testing is not part of current ASD-PAH evaluation protocols. (sources/asd-japc-2025 — medium)

Connections

• Related to concepts/Patent-Foramen-Ovale — PFO is the structural differential, and shares the device but not the evidence
• Related to concepts/ACHD-AP-Classification — secundum ASD classified as Anatomic Class I (Simple)
• Related to concepts/Pulmonary-Hypertension — ASD-PAH is Group 1 pre-capillary PAH; PVR thresholds guide closure decisions
• Related to concepts/PAH-Risk-Stratification — risk stratification determines pharmacotherapy intensity
• Related to entities/Atrial-Fibrillation — AF most common arrhythmia; pre-closure ablation strategy critical
• Related to concepts/Catheter-Ablation-AF — transseptal access through or around the closure device when AF ablation follows implantation
• Related to concepts/SVT-Management — AF management principles apply
• Related to concepts/Intracardiac-Shunts — Qp:Qs measurement methods and limitations

Sources

• sources/asd-ehj-2022
• sources/pfo-jama-2025
• sources/pfo-eso-2024
• sources/asd-lancet-2014
• sources/asd-closure-jc-2015
• sources/shunt-nature-sr-2020
• sources/asd-japc-2025
• sources/af-ablation-asd-device-jce-2020