VSD Patch Closure for Perimembranous VSD

Perimembranous ventricular septal defects (pmVSDs) are the most common VSD subtype and lie adjacent to the membranous septum and atrioventricular (AV) conduction axis. Surgical closure aims to abolish left-to-right shunting while preserving aortic and tricuspid valve function and—critically—the conduction system. Success hinges on recognizing anatomic variants (inlet vs outlet extension), selecting an exposure that reveals the posteroinferior rim, and executing a suture line that protects the conduction tissue [1,2].

Key anatomic relationships

Aortic valve proximity. In pmVSDs, the aortic cusp may abut the superior margin. If the border is uncertain, cardioplegic arrest and careful inspection of leaflet–VSD relationships prevent cusp distortion during patching [1].
AV conduction axis. The conduction system reliably courses along the inferior (posteroinferior) rim of pmVSDs, but its exact depth and “surfacing” depend on the defect’s extension and septal topography; the trabecula septomarginalis can bring the bundle more superficially into harm’s way—especially in outlet-related extensions [1,3].
Right bundle branch (RBB) landmark. On the RV side, the RBB emerges near the base of the medial papillary muscle (MPM) and moderator band complex; stitches placed into this footprint risk RBB injury [1].

Variant anatomy: outlet vs inlet extension

Outlet extension. Extension toward the conal/infundibular septum alters septal relief; depending on the trabecular anatomy, the conduction axis may lie more superficially and closer to the suture line than anticipated. Maintain conduction-aware bites along the inferior rim, biased off-rim [1,3].
Inlet extension. The conduction bundle hugs the inferior border and can be subendocardial on the septal crest; rim-hugging stitches here are hazardous. Accessory papillary muscle support to the septal leaflet may further constrain exposure [1,4].
Operative mapping. Before placing the first stitch, orient the outlet vs inlet margins from both LV and RV perspectives to anticipate where the conduction axis will run [1].

Exposure strategy

Right-atrial approach with selective tricuspid valve detachment (TVD). A transatrial approach is standard; when the tricuspid apparatus obscures the inferior rim, temporary TVD (anterior or septal leaflet) provides orthogonal visualization and safer, shallow bites along the risky rim. Multiple series—including contemporary pediatric cohorts—support TVD’s safety when reattachment is meticulous [2,5–7].
Managing accessory papillary support. Identify and gently mobilize accessory papillary muscles before suturing to avoid leaflet tethering or inadvertent inclusion—especially in inlet-extension defects [1,4].

Patch materials and suture technique (practical approach)

Patch choice. Treated autologous pericardium or thin PTFE/Dacron are appropriate; the contour should re-establish the septal plane without bulging into the LVOT or subtricuspid space [1,2].
Suture line plan. Begin where conduction risk is lowest and keep the inferior limb 1–2 mm off the true rim with short, evenly spaced, partial-thickness bites that respect endocardium. Avoid stitches at the MPM base (RBB landmark) [1,2].
Valve preservation. When an aortic cusp approximates the defect, re-confirm leaflet edges and commissures after arrest; ensure the patch does not protrude into cusp excursion [1].
TVD reattachment. Reattach on the atrial side of the annulus with fine interrupted sutures to preserve coaptation and avoid septal conduction injury; published series show no excess TR or heart block with careful technique [5–7].

Intraoperative checks

Water/saline test (after deairing and reperfusion readiness) to confirm patch competence and leaflet coaptation.
Rhythm surveillance while tying inferior and septal stitches; new junctional rhythm, new RBBB, or PR prolongation should prompt reassessment of bite depth/trajectory [1–3].

Modality selection: surgery vs device closure

Surgery remains the reference standard for pmVSDs, with low mortality in contemporary series and durable results when conduction-aware technique is used [2].
Transcatheter closure can be effective in selected pmVSDs but carries a non-trivial risk of complete AV block (cAVB) due to device pressure/edema at the posteroinferior rim. Early JACC experience highlighted cAVB as the major concern; meta-analyses and large cohorts confirm that although the absolute risk is low, it is clinically meaningful—especially in smaller children—demanding careful case selection, device choice, and long-term rhythm follow-up [8–11].

Pitfalls and how to avoid them

Heart block: inferior-rim stitches too rim-hugging/deep → stay off the posteroinferior edge; use shallow, frequent bites [1].
RBB injury: sutures at the MPM base → identify the MPM and skip this footprint [1].
Residual shunt (inlet-extension): under-visualization → deploy TVD early for orthogonal exposure [2,5–7].
Aortic cusp distortion: patch too proud or bites too close to the cusp edge → reassess borders under cardioplegia and flatten the patch contour [1].
Leaflet tethering (inlet-extension): inadvertent capture of accessory papillary support → identify and free accessory papillary muscles prior to closure [4].

Summary (pearls)

Treat the inferior margin as “conduction territory” and keep the suture line respectfully off-rim [1].
Remember the RBB–MPM relationship; never anchor to the MPM base [1].
Use TVD liberally when exposure is marginal; restore leaflet geometry carefully [2,5–7].
In inlet extension, assume the conduction axis hugs the inferior border; bias the patch away from it [4].
Consider transcatheter closure only in carefully selected pmVSDs and ensure structured rhythm follow-up given the cAVB signal [8–11].

References

[1] Anderson RH. The surgical anatomy of ventricular septal defect. J Thorac Cardiovasc Surg. 1992;104(6):1681–1690.

[2] Mullen JC, Heim C, Cochrane A, West K, Butchart E, Duncan K, et al. Perimembranous ventricular septal defect repair: keeping it simple. Ann Thorac Surg. 1996;62(5):1233–1237.

[3] Kurosawa H, Becker AE. Modification of the precise relationship of the atrioventricular conduction bundle to the margins of the ventricular septal defects by the trabecula septomarginalis. J Thorac Cardiovasc Surg. 1984;87(4):605–615.

[4] Yamashiro T, Hatanaka M, Kimura S, Saito S, Hasegawa T, Takahashi Y. Surgical landmarks of course of atrioventricular conduction bundle in ventricular septal defect. J Thorac Cardiovasc Surg. 1989;98(5 Pt 2):888–893.

[5] Zhao J, Zhou Q, Zhang B, Song Y, Hou J. Tricuspid Valve Detachment in Closure of Congenital Ventricular Septal Defect. Tex Heart Inst J. 2003;30(4):287–290.

[6] Bang JH, Bae EJ, Kim WH, Lim HG, Lee JR, Kim YJ. Detachment of the tricuspid valve for ventricular septal defect repair in infants younger than 3 months. J Thorac Cardiovasc Surg. 2016;152(2):491–497.

[7] Ashry A, Kothapalli S, Watanabe K, Shi Y, Ichihara T, Dearani JA. Ventricular Septal Defect Exposure by Tricuspid Valve Chordal Detachment. Ann Thorac Surg. 2023;115(6):e445–e447.

[8] Butera G, Carminati M, Chessa M, Piazza L, Micheletti A, Negura DG, et al. Transcatheter closure of perimembranous ventricular septal defects: early and long-term results. J Am Coll Cardiol. 2007;50(12):1189–1195.

[9] Santhanam H, Yang L, Chen Z, Tai BC, Rajgor DD, Quek SC, et al. A meta-analysis of transcatheter device closure of perimembranous ventricular septal defects. Int J Cardiol. 2018;254:75–83.

[10] Carminati M, Butera G, Chessa M, De Giovanni J, Fisher G, Gewillig M, et al. Transcatheter closure of congenital ventricular septal defects: results of an international registry. Circulation. 2007;115(4):549–555.

[11] Bai Y, Xu XD, Li CY, Li YM, Wang BP, Wang C, et al. Complete atrioventricular block after percutaneous device closure of perimembranous ventricular septal defect using the modified double-disk occluder: a 1046-case experience. Circ Arrhythm Electrophysiol. 2015;8(5):1184–1191.

[12] Shahanavaz S, Moore JW, Justino H. What Is Blocking Transcatheter Ventricular Septal Defect Closure? J Am Heart Assoc. 2022;11(7):e024963.