Transcatheter Sinus Venosus ASD Closure in Severe Pulmonary Hypertension

Abstract

Background

Data on sinus venosus atrial septal defect (SVASD) closure in patients with coexistent pulmonary arterial hypertension (PAH) are scarce because current guidelines restrict closure to a pulmonary vascular resistance (PVR) of <5 WU.

Case Summary

A 20-year-old woman with severe PAH and a PVR of 12.6 WU underwent successful transcatheter SVASD and partial anomalous pulmonary venous return correction. A small atrial communication was intentionally created as a temporary safety “pop-off,” enabling aggressive postprocedural escalation of PAH therapy.

Why Beyond the Guidelines?

Patients with severe PAH may still benefit from transcatheter SVASD closure despite guidelines. These patients require highly individualized, nonguideline-directed interventions.

Discussion

Current guidelines restrict ASD closure to PVR <5 WU, and prior data on closure at higher resistances are largely limited to secundum defects. This successful fenestrated SVASD closure at a baseline PVR of 12.6 WU challenges the utility of relying on a single hemodynamic threshold. Creating a temporary, controlled fenestration provides an essential safety margin, expanding interventional options for high-risk patients who would otherwise be precluded from care.

Take-Home Message

Transcatheter closure of SVASD in patients with severe PAH can effectively reduce the left-to-right shunt and facilitate escalation of PAH-targeted therapies.

Visual Summary

Closing an atrial septal defect (ASD) in the presence of coexisting pulmonary arterial hypertension (PAH) poses a therapeutic dilemma. Pulmonary vasodilator therapy can worsen left-to-right shunting across the defect, accelerating pulmonary vascular disease. Conversely, complete closure risks eliminating a decompressing right-to-left “pop-off,” potentially precipitating acute right ventricular (RV) failure.

A sinus venosus atrial septal defect (SVASD) is typically associated with partial anomalous pulmonary venous return (PAPVR), creating an obligatory left-to-right shunt that traditionally mandates surgical redirection. Recently, transcatheter covered-stent techniques have emerged as a viable alternative for anatomically suitable candidates.1, 2, 3 We report a case of successful transcatheter correction of an SVASD with PAPVR in a young adult with severe PAH, achieved by deliberately creating a small atrial communication.

Case Summary

History of presentation

A 20-year-old woman (38.6 kg) with SVASD, PAPVR, and severe PAH presented for interventional evaluation. She was highly symptomatic, with severely limited exercise capacity despite triple oral combination therapy (selexipag, macitentan, and tadalafil) and nighttime supplemental oxygen (Table 1).

Table 1.

Comparison of NYHA Functional Class, PH Therapy, 6-Minute Walk Test and Cardiac MRI Indices Before and After Transcatheter Correction of Sinus Venosus ASD

	Before SVASD Closure	6-Month Post-SVASD Closure
NYHA functional class	II/III	I
PH therapy	Selexipag, macitentan, and tadalafil nighttime oxygen (+)	Selexipag, macitentan, tadalafil, and sotatercept nighttime oxygen (−)
6-minute walk test	Walked for a total of 445 m, with symptoms of shortness of breath during the test and a lowest oxygen saturation of 84%	Total of 490.6 m without symptoms and lowest oxygen saturation of 94%
Cardiac MRI indices	RVEF 47% RVEDVi 136 mL/m2 RVESVi 72 mL/m2 RVEDV: LVEDV ratio 1.9 Qp/Qs 1.32:1	RVEF 45% RVEDVi 85 mL/m2 RVESVi 47 mL/m2 RVEDV: LVEDV ratio 1.2 Qp/Qs 0.82

ASD = atrial septal defect; LVEDV = left ventricular end-diastolic volume; MRI = magnetic resonance imaging; PH = pulmonary hypertension; RVEDVi = right ventricular end-diastolic volume index; RVEF = right ventricular ejection fraction; RVESVi = right ventricular end-systolic volume index; SVASD = sinus venosus atrial septal defect.

Past medical history

She was diagnosed at age 17 years after a syncopal episode during cheer practice. Initial echocardiogram and cardiac catheterization demonstrated SVASD, PAPVR (right upper and middle pulmonary veins draining to the superior vena cava [SVC]), a severely dilated RV, suprasystemic RV systolic pressures, and a baseline PVR of 20 WU without response to vasoreactivity testing. Her baseline pulmonary-to-systemic blood flow ratio (Qp/Qs) was 0.8:1. After diagnosis, she was placed on the pulmonary vasodilators noted above. Despite therapy, she remained symptomatic with limited exercise capacity (Table 1). She was referred to our institution for possible intervention.

Investigation

Preprocedural evaluation at our center, including echocardiography, computed tomography, and cardiac magnetic resonance imaging (CMR), confirmed the anatomy and severe PAH. CMR-derived Qp/Qs indicated a net left-to-right shunt of 1.3. Diagnostic cardiac catheterization demonstrated a suprasystemic RV pressure of 112 mm Hg, a mean pulmonary artery pressure of 75 mm Hg, and a pulmonary capillary wedge pressure of 13 mm Hg. Saturation studies measured a net right-to-left shunt with a Qp/Qs of 0.8. The indexed PVR was 16.9 indexed WU (absolute PVR of 12.6 WU). Acute vasoreactivity testing was deferred. Systemic hypotension under general anesthesia was thought to underestimate the degree of left-to-right shunting. Therefore, given the significant clinical symptoms and despite the high PVR, we elected to proceed with transcatheter SVASD closure combined with deliberate creation of a small secondary ASD to serve as a hemodynamic “pop-off.” Through the newly created atrial communication, the wire was positioned in the right upper pulmonary vein. Transesophageal echocardiography was used to ensure no right pulmonary venous obstruction. A custom-made 8.4-cm-long covered stent (10-zig G-Armor; NuMed Inc) was delivered from the SVC to the mid-right atrium using a 22 mm × 8-cm balloon-in-balloon catheter, while a 12 mm × 4-cm ATLAS Gold balloon (BD) was simultaneously inflated in the right upper pulmonary vein to preserve venous drainage. To prevent inferior migration of the stent, an anchoring stent (36 mm-long IntraStent Max LD; Medtronic) was deployed in the SVC just inferior to the innominate vein entry, telescoping the superior aspect of the covered stent. To further seal the SVASD, the inferior margin of the covered stent was flared using a 26 mm × 2-cm Atlas Gold balloon. Angiography and transesophageal echocardiography confirmed complete exclusion of the SVASD without right pulmonary venous obstruction (Figure 1). Finally, a controlled fenestration was created via a separate transseptal puncture and dilated with a 12 mm × 4-cm Atlas Gold balloon.

Figure 1.

Angiography Prior to and Following Placement of Covered Stent to Close the SVASD

(A) A fluoroscopic image from a straight frontal projection demonstrating a large sinus venosus atrial septal defect (ASD) with contrast filling the left atrium. (B)Another fluoroscopic image postcovered stent and superior anchoring stent placement demonstrating right upper pulmonary vein (RUPV) patency and no residual shunt across the sinus venous ASD. LA = left atrium; RA = right atrium; SVC = superior vena cava; TEE = transesophageal echocardiography.

Why beyond the guidelines?

The 2025 adult congenital heart disease guidelines recommend ASD closure only if PVR is <5 WU and Qp/Qs ≥1.5. For patients with severe PAH and elevated resistance, the guidelines suggest a conservative “treat-and-repair” strategy, delaying closure until PVR falls below 5 WU. Our patient presented with an absolute PVR of 12.6 WU, far exceeding standard thresholds.

The literature describing transcatheter closure of ASDs in patients with advanced PAH is largely limited to secundum ASDs. Furthermore, published reports of transcatheter SVASD closure have generally been limited to patients with more favorable hemodynamics. In contrast, our patient had severe PAH with markedly elevated PVR, requiring modification of the conventional transcatheter approach by intentionally creating a temporary “pop-off” to provide hemodynamic protection while permitting optimization of pulmonary vasodilator therapy.

Case outcome and follow-up

The patient tolerated the procedure well and was discharged the next day. Her baseline pulse oximetry saturation improved to 96%. The discharge echocardiogram demonstrated satisfactory stent position, no residual SVASD flow, and an exclusively left-to-right shunt across the created small ASD. After recovery, her medical regimen was augmented with sotatercept.

At the 6-month follow-up, she demonstrated significant improvement in functional capacity, with NYHA functional class improving from II/III to I. On the 6-minute walk test, she walked further without symptoms or desaturation, a significant improvement from preprocedure. A repeat CMR demonstrated a reduction in RV end-diastolic volume index from 136 to 85 mL/m² (Figure 2).

Figure 2.

Cardiac Magnetic Resonance Imaging

A 4-chamber cine image before sinus venosus atrial septal defect (SVASD) closure (A) demonstrating a severely dilated right ventricle as well as sinus venosus ASD. (B) A similar image 6 months postprocedure demonstrating significant improvement in the size of the right ventricle. RV = right ventricular.

Discussion

Management of patients with ASDs and severe PAH remains challenging. The 2025 American Heart Association/American College of Cardiology adult congenital heart disease guidelines recommend ASD closure in patients with a left-to-right shunt of ≥1.5:1 and PVR <5 WU. If PVR is above 5 WU, fenestrated ASD closure may be considered after reducing PVR to <5 WU using a “treat-and-repair” approach.⁴

Despite these recommendations, limited case series have reported successful ASD closure in patients with PVR >5 WU.^5,6,7 However, these series involve patients with secundum ASDs. Treatment of SVASD associated with PAH is rare and limited to only a few documented cases in older adults with a PVR <5 WU.^8,9

Our successful fenestrated closure of a SVASD in a patient with a baseline PVR of 12.6 WU highlights this limitation. The successful outcome suggests that relying on a single hemodynamic threshold may be less useful than previously believed. Creating a temporary, controlled fenestration provides a safety margin for patients such as ours whose baseline hemodynamics would otherwise preclude them from interventional consideration.^10,11

Surgical correction of SVASD and PAPVR remains the standard treatment, despite evolving transcatheter techniques. However, our patient was considered a high-risk surgical candidate because of coexistent severe pulmonary vascular disease that persisted despite targeted pulmonary vasodilator therapy. Alternative management strategies include continued escalation of pulmonary vasodilator therapy followed by delayed surgical or transcatheter defect closure if PVR decreases sufficiently (the “treat-and-repair” strategy).^12,13 For patients with irreversible pulmonary vascular disease despite maximal medical therapy, transplantation may also be considered; either isolated lung transplantation or combined heart-lung transplantation may be required.

Conclusions

Successful transcatheter closure of an SVASD is feasible even in the setting of severe PAH and markedly elevated PVR. Eliminating the left-to-right shunt decompresses the right heart and may facilitate aggressive escalation of PAH-directed therapies. Creating a temporary ASD “pop-off” is a valuable safety measure to prevent acute RV failure and pulmonary hypertensive crisis during the immediate postprocedural period.

Take-Home Messages

• •Deliberate creation of an atrial septal defect “pop-off” after transcatheter sinus venosus atrial septal defect closure provides an important safety measure against acute hemodynamic compromise in patients with severe pulmonary hypertension.
• •Eliminating a hemodynamically significant left-to-right shunt in patients with pulmonary vascular resistance well above standard guideline thresholds may facilitate more effective optimization and escalation of advanced, targeted pulmonary arterial hypertension therapies.

Visual Summary.

Transcatheter Sinus Venosus ASD Closure With a Deliberate Atrial “Pop-Off” in Severe Pulmonary Hypertension

(A) Baseline anatomy showing a sinus venosus atrial septal defect (SVASD) with partial anomalous pulmonary venous return (PAPVR) of the right upper and middle pulmonary veins draining into the superior vena cava (SVC)/right atrial junction, with the right lower pulmonary vein draining normally into the left atrium (LA). Baseline pulmonary vascular resistance (PVR) was severely elevated at 12.6 WU, well above the guideline threshold of <5 WU for standard defect closure. (B) A covered stent is deployed across the SVASD to baffle anomalous pulmonary venous return toward the left atrium and exclude the interatrial communication, while a balloon is inflated within the right upper pulmonary vein (RUPV) to protect its ostium during stent deployment. (C) A deliberate, controlled atrial septal “pop-off” is created adjacent to the excluding stent, functioning as a safety valve to allow transient right-to-left decompression and to mitigate the risk of acute right ventricular (RV) failure in the setting of severe, fixed pulmonary hypertension. Following the procedure and escalation of pulmonary arterial hypertension (PAH)-targeted therapy, the patient demonstrated improvement in NYHA functional class (II-III to I) and RV reverse remodeling, with RV end-diastolic volume index decreasing from 136 to 85 mL/m² at 6-month follow-up. LV = left ventricle; RA = right atrium.

Funding Support and Author Disclosures

The authors have reported that they have no relationships relevant to the contents of this paper to disclose.