VSD Classification

Date
February 17, 2026
URL
https://x.com/WithAScalpel/status/2023743704482082827?s=20
Categories
VSD

VSD Classification:

image

VSDs are most reproducibly classified by their anatomic borders as viewed from the right ventricle—i.e., what tissue forms the rim of the defect—and secondarily by their relationship to right-ventricular components (inlet, trabecular/apical, outlet/infundibular). This “border-first” approach remains the most clinically actionable because it anticipates (i) conduction system proximity, (ii) semilunar/AV-valve vulnerability, and (iii) closure strategy and residual-lesion risk. [1, 2, 3]

1) Orientation: Key right-ventricular landmarks (RV en-face surgical view)

Accurate classification begins with consistent RV landmarks:

  • Membranous septum (fibrous): adjacent to the penetrating His bundle → highest iatrogenic AV block risk when part of the rim. [1, 7]
  • Tricuspid valve (TV): anchors the inlet region; septal/anterior leaflets and their chordal insertions matter for exposure and suture placement. [7]
  • Aortic valve (AoV) and pulmonary valve (PV): define the outlet region; proximity or fibrous continuity predicts cusp support and regurgitation risk. [1, 6]
  • Ventriculo-infundibular fold / outlet (infundibular) septum: determines whether there is a muscular separation from semilunar valves. [1, 7]
  • Septomarginal trabeculation (septal band) and moderator band: trabecular RV reference points; useful for localizing muscular/apical defects and maintaining consistent language across echo–OR communication. [1]

2) The three consensus morphologic groups (borders define the category)

A) Perimembranous VSD (PM-VSD)

Definition (border concept): the defect has the membranous septum as a direct border (often with fibrous continuity involving adjacent AV/arterial structures). [1, 2]

Signature risk: proximity to the atrioventricular conduction axis → conduction-protective closure strategy is central. [1, 7]

Subtyping by RV “opening” (useful for operative planning):

  1. Outlet-type PM-VSD: perimembranous defect extending toward the outlet septum and opening into the RV outflow beneath the arterial valve region. [1]
  2. Central (confluent) PM-VSD: larger perimembranous defect extending across trabecular septum, potentially “reaching” multiple RV components; may coexist with TV overriding and becomes a combined septation + AV-valve management problem rather than simple hole closure. [1, 8]
  3. Inlet-type PM-VSD: perimembranous defect opening mainly toward the RV inlet, near septal/anterior TV leaflets. [1, 7]

Practical surgical implication (why this category matters):

  • The patch suture line is constrained by where a surgeon can safely place stitches along the rims; perimembranous borders are the classic setting where “safe rims” and the conduction axis conflict. [7]

B) Muscular VSD

Definition (border concept): the defect is completely rimmed by muscle, without a membranous border and without direct fibrous continuity to valvar leaflets. [1, 3]

Signature risk pattern: generally lower risk of direct valve-tissue distortion; challenges are multiplicity, exposure, and residual shunts, especially in apical/trabecular locations. [1]

Subtyping by RV location (as in your slides):

  1. Outlet muscular VSD: within the infundibular septum, opening into RV outflow but separated from semilunar leaflets by muscle (key distinction from juxtaarterial defects). [1]
  2. Apical trabecular muscular VSD: within the trabecular/apical septum; may be multiple (“Swiss-cheese” phenotype). [1]
  3. Inlet muscular VSD: within inlet septum; fully muscular rim, opening toward RV inlet and influenced by TV chordal geometry. [1]

Imaging note (clinically important limitation):

  • Even with careful scanning, trabecular/apical muscular defects are the most likely to be underestimated or missed compared with perimembranous or outlet-adjacent lesions, reinforcing the need to integrate multiple echocardiographic windows and Doppler interrogation. [2, 3]

C) Doubly committed juxtaarterial VSD (DCJA; “subarterial” / “supracristal” phenotype)

Definition (border concept): the defect is bordered by both arterial valves, with fibrous continuity between the aortic and pulmonary valvar leaflets—reflecting deficiency/absence of the muscular outlet septum. [1, 6]

Signature complication: aortic cusp prolapse and progressive aortic regurgitation (AR) due to loss of cusp support. [6]

Operative outcome signal (why timing matters):

  • Large clinical series show a high prevalence of preoperative aortic prolapse and AR, and demonstrate that timely repair can stabilize valve function—most patients achieve trivial/no residual AR when managed appropriately. [6]

3) A practical echo → OR workflow (compact and reproducible)

Step 1 — Define borders (category)

  • Membranous septum in the rim → perimembranous. [1]
  • Entire muscular rim → muscular. [1, 3]
  • Arterial–arterial fibrous continuity / outlet septum deficiency → DCJA. [1, 6]

Step 2 — Map RV component (subtype language that improves team alignment)

  • Inlet vs trabecular/apical vs outlet determines exposure, patch geometry, and valve-tissue relationships. [1, 7]

Step 3 — Anticipate the “dominant hazard”

  • PM-VSD: conduction axis / TV tissue handling. [1, 7]
  • Muscular VSD: multiplicity, access, residual shunt risk. [1, 2]
  • DCJA: aortic cusp prolapse and AR trajectory (valve-threatening lesion). [6]

4) Nomenclature harmonization (why consistent terms matter)

International surgical and coding frameworks have converged toward border-based definitions to reduce ambiguity across echocardiography, catheterization, operative reports, and registries—supporting consistent communication and outcomes reporting. [4, 5, 9]

References

[1] Soto B, Becker AE, Moulaert AJ, Lie JT, Anderson RH. Classification of ventricular septal defects. Br Heart J. 1980;43(3):332-343. doi:10.1136/hrt.43.3.332.

[2] Sutherland GR, Godman MJ, Smallhorn JF, Guiterras P, Anderson RH, Hunter S. Ventricular septal defects. Two dimensional echocardiographic and morphological correlations. Br Heart J. 1982;47(4):316-328. doi:10.1136/hrt.47.4.316.

[3] Capelli H, Somerville J, McCartney FJ, Taylor JFN, Anderson RH. Classification of the site of ventricular septal defect by 2-dimensional echocardiography. Am J Cardiol. 1983;51(9):1474-1480. doi:10.1016/0002-9149(83)90660-4.

[4] Jacobs JP, Burke RP, Quintessenza JA, Mavroudis C. Congenital Heart Surgery Nomenclature and Database Project: ventricular septal defect. Ann Thorac Surg. 2000;69(4 Suppl):S25-S35. doi:10.1016/S0003-4975(99)01270-9.

[5] Lopez L, Houyel L, Colan SD, et al. Classification of Ventricular Septal Defects for the Eleventh Iteration of the International Classification of Diseases—Striving for Consensus: A Report From the International Society for Nomenclature of Paediatric and Congenital Heart Disease. Ann Thorac Surg. 2018;106(5):1578-1589. doi:10.1016/j.athoracsur.2018.06.020.

[6] Devlin PJ, McGuirk SP, Yan G, et al. Doubly committed and juxtaarterial ventricular septal defect: outcomes of the aortic and pulmonary valves. Ann Thorac Surg. 2014;97(6):2136-2143. doi:10.1016/j.athoracsur.2014.01.059.

[7] Anderson RH, Wilcox BR. The surgical anatomy of ventricular septal defect. J Card Surg. 1992;7(1):17-35. doi:10.1111/j.1540-8191.1992.tb00773.x.

[8] Anderson RH, Wilcox BR. The surgical anatomy of ventricular septal defects associated with overriding valvar orifices. J Card Surg. 1993;8(2):130-142. doi:10.1111/j.1540-8191.1993.tb00363.x.

[9] Anderson RH, Ho SY, Wilcox BR. The surgical anatomy of ventricular septal defect part IV: double outlet ventricle. J Card Surg. 1996;11(1):2-11. doi:10.1111/j.1540-8191.1996.tb00002.x.