Doubly Committed Juxtaarterial VSD #2: Surgical Repair

A doubly committed juxtaarterial ventricular septal defect (DCJA VSD), also termed a doubly committed subarterial or supracristal VSD, is an outlet-type defect located immediately beneath both the aortic and pulmonary valves. Its defining anatomical feature is the absence or marked deficiency of the outlet/infundibular septum, resulting in fibrous continuity between the aortic and pulmonary valves. This anatomy makes the lesion fundamentally different from a perimembranous VSD: the main surgical issue is not only septal closure, but also preservation of semilunar valve geometry [1, 2].

1. Anatomical Concept

In DCJA VSD, the defect opens directly beneath the arterial valves. The superior rim is frequently deficient because the muscular infundibular septum is absent. As a result, the upper border of the defect may be formed by fibrous tissue adjacent to the pulmonary valve hinge and aortic cusp support rather than by a robust muscular septal rim.

This anatomy has three practical implications:

1. The aortic valve is vulnerable.

The right coronary cusp, and occasionally adjacent cusp tissue, may prolapse into the defect, producing progressive aortic regurgitation [3, 4].

2. The pulmonary valve must be protected.

Because the repair is commonly performed through the pulmonary artery, the pulmonary valve leaflets and their hinge points are directly involved in the operative field [5].

3. The conduction axis is usually remote from the main outlet defect.

Unlike a typical perimembranous VSD, the atrioventricular node and His bundle are generally away from the superior outlet margin. However, caution remains necessary if the defect extends posteroinferiorly or has a perimembranous component.

2. Indication for Repair

The indication for repair is based not only on shunt volume but also on the risk of progressive aortic cusp prolapse and aortic regurgitation.

Even a restrictive DCJA VSD may require closure if there is:

• Aortic cusp prolapse
• New or progressive aortic regurgitation
• Evidence of semilunar valve distortion
• Significant left-to-right shunt
• Progressive LV volume loading
• Concern for long-term aortic valve damage

The natural history is important: once aortic cusp prolapse begins, aortic regurgitation may progress during observation. Surgical series have shown that delay after the onset of AR is associated with a higher likelihood of persistent postoperative AR [3, 4]. Therefore, early closure is generally favored once cusp prolapse or AR is identified.

3. Operative Exposure: Why the Transpulmonary Approach?

The transpulmonary approach provides direct exposure of the outlet VSD through an incision in the main pulmonary artery. This is the preferred strategy in many centers because the defect lies immediately beneath the pulmonary valve and can be visualized directly from the arterial side [5].

Advantages of the transpulmonary approach

• Direct view of the superior and anterior margin of the VSD
• Excellent visualization of the pulmonary valve hinge
• Reduced need for extensive tricuspid valve manipulation
• Ability to assess the relationship between the VSD, pulmonary valve, and aortic valve
• Precise placement of sutures along the deficient superior rim

In a large contemporary series, the transpulmonary approach was used in most patients, with excellent survival, no residual shunt, and no reported complete heart block [5].

4. Patch Closure: Technical Principles

Patch closure remains the standard surgical strategy for DCJA VSD repair [6]. The objective is to close the interventricular communication while restoring support to the outlet septal region and avoiding distortion of the semilunar valves.

Key technical steps

1. Expose the defect through the main pulmonary artery.

The pulmonary valve leaflets are gently retracted to identify the VSD margins.

2. Define the inferior, posterior, and superior borders.

The inferior and posterior margins usually provide more reliable tissue for suture placement.

3. Recognize the deficient superior rim.

The superior margin often lacks muscular tissue. Sutures may need to be placed near the pulmonary valve base or hinge, either from the pulmonary arterial side or ventricular side.

4. Avoid semilunar valve distortion.

Sutures should not tether the pulmonary valve leaflet or deform the aortic cusp support.

5. Tailor the patch carefully.

The patch should be large enough to close the defect without tension, but not so redundant that it bulges into the RVOT or impairs pulmonary valve motion.

5. The Superior Rim: The Critical Surgical Zone

The superior rim is the most delicate part of the repair. Because the infundibular septum is absent, there may be no true muscular shelf for secure anchoring. The surgeon must therefore use adjacent fibrous tissue and the pulmonary valve hinge region carefully.

The technical balance is precise:

• Too superficial: risk of residual shunt
• Too deep or too close to the leaflet: risk of pulmonary valve distortion
• Too much traction: risk of altered semilunar valve geometry
• Poor patch orientation: risk of RVOT turbulence or valve dysfunction

Modern surgical series suggest that carefully placed sutures through or near the pulmonary valve base can be performed without clinically significant late pulmonary insufficiency in most patients [5].

6. Aortic Valve Considerations

Aortic valve preservation is a central goal of DCJA VSD repair. The mechanism of aortic regurgitation is usually related to loss of cusp support and prolapse of the right coronary cusp into the defect. The shunt jet and Venturi effect may further exaggerate cusp deformation over time.

Surgical decision-making

• No or trivial AR: VSD patch closure alone is often sufficient.
• Mild AR with cusp prolapse: early VSD closure may stabilize or improve AR by restoring support and eliminating the shunt.
• Moderate or severe AR: additional aortic valve repair may be required, depending on cusp morphology and coaptation.

Several studies have shown that preoperative severity and duration of AR are important predictors of postoperative valve outcome [3, 4, 7]. Once cusp deformation becomes established, VSD closure alone may not fully reverse the valve lesion.

7. Pulmonary Valve Considerations

Because the operative field is accessed through the pulmonary artery, pulmonary valve preservation must be deliberate. The pulmonary leaflets should be handled gently, and the patch should not restrict leaflet excursion.

Important points include:

• Avoid excessive traction on the pulmonary leaflets.
• Place superior sutures symmetrically and precisely.
• Confirm that the patch does not narrow the RVOT.
• Reassess pulmonary valve motion after closure.
• Avoid creating pulmonary regurgitation by tethering the leaflet hinge.

Long-term data suggest that pulmonary valve outcomes are generally favorable when the transpulmonary approach and patch fixation are performed carefully [5].

8. Conduction System

The conduction axis is less central to the operative risk than in perimembranous VSD closure. In DCJA VSD, the defect is located in the outlet septum, and the atrioventricular conduction tissue usually lies posterior and inferior to the main defect.

However, the surgeon should remain cautious in the posteroinferior margin, especially when:

• The defect extends toward the membranous septum
• There is associated perimembranous extension
• The anatomy is distorted by cusp prolapse
• Exposure is limited
• Patch sutures are placed deeply along the inferior margin

Contemporary outcome series report very low rates of complete heart block after DCJA VSD repair, supporting the concept that the conduction axis is usually remote from the principal outlet defect [5].

9. Intraoperative Assessment

After patch closure, the repair should be evaluated systematically with direct inspection and intraoperative echocardiography.

Essential checkpoints

• No residual VSD shunt
• No new or worsened aortic regurgitation
• No pulmonary valve distortion
• No pulmonary stenosis or significant pulmonary insufficiency
• No RVOT obstruction
• Preserved ventricular function
• Stable rhythm without conduction abnormality

The operation should be considered successful only when both goals are achieved: complete shunt closure and preservation of semilunar valve competence.

10. Long-Term Outcomes

Surgical outcomes after DCJA VSD repair are generally excellent when repair is performed before irreversible aortic cusp deformation occurs. Large surgical series have reported excellent operative survival, low residual shunt rates, and favorable aortic and pulmonary valve outcomes [5, 8, 9].

However, the long-term concern remains aortic regurgitation. Patients with preoperative aortic cusp prolapse or established AR require careful follow-up, because AR may persist or progress even after technically successful VSD closure [4, 7, 10].

Surgical Take-Home Message

DCJA VSD repair should be understood as a semilunar valve-preserving outlet septal reconstruction, not simply as VSD closure.

The transpulmonary approach provides direct exposure of the defect and allows precise patch placement along the deficient superior rim. The central technical challenge is to anchor the patch securely while avoiding distortion of the pulmonary valve and maintaining aortic cusp competence. Early repair is particularly important when aortic cusp prolapse or AR is present, because delayed intervention may reduce the likelihood of complete postoperative aortic valve recovery.

Summary

Doubly committed juxtaarterial VSD is characterized by absence of the infundibular septum and direct proximity of the defect to both semilunar valves. The transpulmonary approach offers excellent exposure and is widely used for patch closure. The deficient superior rim requires careful suture placement near the pulmonary valve hinge, while the aortic valve must be protected from progressive cusp prolapse and regurgitation. Although the conduction axis is usually away from the outlet defect, careful attention remains necessary along the posteroinferior margin. The optimal repair eliminates the shunt, preserves RVOT geometry, and maintains long-term aortic and pulmonary valve competence.

References

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[2] Schmidt KG, Cassidy SC, Silverman NH, Stanger P. Doubly committed subarterial ventricular septal defects: echocardiographic features and surgical implications. J Am Coll Cardiol. 1988;12(6):1538-1546.

[3] Komai H, Naito Y, Fujiwara K, Noguchi Y, Nishimura Y, Uemura S. Surgical strategy for doubly committed subarterial ventricular septal defect with aortic cusp prolapse. Ann Thorac Surg. 1997;64(4):1146-1149.

[4] Tomita H, Arakaki Y, Ono Y, Yamada O, Tsukano S, Yagihara T, Echigo S. Evolution of aortic regurgitation following simple patch closure of doubly committed subarterial ventricular septal defect. Am J Cardiol. 2000;86(5):540-542.

[5] Devlin PJ, Russell HM, Mongé MC, Patel A, Costello JM, Spicer DE, Anderson RH, Backer CL. Doubly committed and juxtaarterial ventricular septal defect: outcomes of the aortic and pulmonary valves. Ann Thorac Surg. 2014;97(6):2134-2141.

[6] Shamsuddin AM, Chen YC, Wong AR, Le TP, Anderson RH, Corno AF. Surgery for doubly committed ventricular septal defects. Interact Cardiovasc Thorac Surg. 2016;23(2):231-234.

[7] Brauner R, Birk E, Sahar G, Blieden L, Vidne BA. Surgical management of ventricular septal defect with aortic valve prolapse: clinical considerations and results. Eur J Cardiothorac Surg. 1995;9(6):315-319.

[8] Sim EK, Grignani RT, Wong ML, Quek SC, Wong JC, Yip WC, Lee CN. Outcome of surgical closure of doubly committed subarterial ventricular septal defect. Ann Thorac Surg. 1999;67(3):736-738.

[9] Hisatomi K, Taira A, Moriyama Y. Is direct closure dangerous for treatment of doubly committed subarterial ventricular septal defect? Ann Thorac Surg. 1999;67(3):756-758.

[10] Waqar T, Rizvi MFA, Baig AR. Doubly committed subarterial ventricular septal defect repair: an experience of 51 cases. Pak J Med Sci. 2017;33(5):1112-1116.