Rastelli Classification of Complete AVSD #3: Rastelli Type C

1. Definition

Rastelli type C is the form of complete atrioventricular septal defect (complete AVSD) in which the superior bridging leaflet (SBL) has no chordal attachment to the crest of the ventricular septum. The central portion of the leaflet therefore bridges freely across the ventricular septal defect (VSD), producing the characteristic “free-floating” superior bridging leaflet. This configuration represents the greatest degree of superior leaflet bridging in the classic Rastelli spectrum. The original classification was based primarily on the morphology and ventricular attachments of what was historically termed the common anterior leaflet. [1] (PubMed)

The Rastelli classification remains useful as a concise description of common atrioventricular valve morphology, but it should not be interpreted as a complete description of the valve. Modern surgical assessment must additionally define the inferior bridging leaflet, mural leaflets, papillary muscles and chordal architecture, ventricular balance, VSD geometry, and both ventricular outflow tracts. [2–5]

2. Core Morphology of Rastelli Type C

All complete AVSDs are characterized by a common atrioventricular junction guarded by a common atrioventricular valve, together with deficiencies of atrial and ventricular septation. The valve typically consists of superior and inferior bridging components and mural components extending toward each ventricular free wall. [2,3]

In Rastelli type C, the defining feature is the relationship between the SBL and ventricular septum:

• No supporting chordae insert into the ventricular septal crest.
• The SBL extends broadly across the plane of the ventricular septum and is free floating over the ventricular component of the defect.
• The ventricular communication beneath the leaflet is consequently generally unobstructed by septal chordal attachments.
• With increasing rightward bridging of the SBL, the separate right anterosuperior valvar component becomes progressively smaller. [2–4]

Morphologic studies support the concept that Rastelli types A, B, and C represent a spectrum of increasing bridging rather than three completely discrete valve designs. Piccoli and colleagues demonstrated that increasing extension of the anterior/superior bridging leaflet into the right ventricle was accompanied by progressive reduction in the size of the separate right anterior leaflet. [2]

The supplied schematic emphasizes the free-floating SBL, small right anterosuperior component, common AV junction, and displaced AV node.

Figure 1. Rastelli type C complete AVSD. The superior bridging leaflet extends across the ventricular septum without attachment to the septal crest. The absence of central tethering creates the characteristic free-floating appearance.

3. Subvalvar Apparatus: An Important Distinction From Type B

The subvalvar anatomy is particularly important when differentiating types B and C.

In Rastelli type B, the SBL extends farther into the right ventricle than in type A, but it remains supported by chordae that attach to an anomalous right ventricular papillary muscle, often located relatively apically or medially. In contrast, an anomalous apical papillary muscle is not the defining feature of Rastelli type C. In classic type C, the central SBL lacks septal or anomalous papillary-muscle attachment and is supported laterally from the papillary apparatus of the respective ventricles. [1–3]

Thus, the essential distinction is:

Type B = bridging leaflet tethered within the right ventricle by an anomalous papillary-muscle/chordal attachment.

Type C = bridging leaflet not tethered to the ventricular septum and truly free floating centrally.

Individual hearts may show intermediate or atypical chordal patterns, and the anatomy does not always fit perfectly into one category. Accordingly, the operative description should document the actual chordal insertions rather than relying exclusively on the Rastelli label.

The inferior bridging leaflet (IBL) also deserves independent assessment. Akiba and colleagues demonstrated considerable variability in its relationship to the septum, including direct, membranous, multiple-chordal, and nearly free-floating configurations, without a predictable relationship to the Rastelli classification of the superior leaflet. [5] Consequently, identification of a type C SBL does not imply that the inferior portion of the valve is similarly free floating.

4. Frequency and Association With Trisomy 21

Type C is generally the second major morphologic pattern after type A, whereas type B is consistently uncommon. The exact proportions vary substantially according to the population studied and the inclusion of unbalanced AVSD, heterotaxy, conotruncal abnormalities, and other complex anatomy.

In a morphometric study of 133 hearts with a common AV valve orifice, Suzuki and colleagues identified type A morphology in 56%, type C in 40%, and type B in only 4%. [4] (JACC) These figures illustrate why a single prevalence such as “35%” should be regarded as an approximate teaching value rather than a universal frequency.

Type C is also enriched among patients with trisomy 21, although reported proportions vary. A 2025 morphologic analysis of 129 unrepaired AV canal specimens found substantially more type C morphology in hearts from patients with Down syndrome: among classifiable complete defects, type C was identified in 40.5% of the Down syndrome group versus 13.5% of the non–Down syndrome group. [6] (DOI) Therefore, the association between trisomy 21 and type C is well supported, but a fixed figure such as “60% of patients with trisomy 21 have type C” is cohort dependent and should not be treated as a universal prevalence estimate.

5. Association With Conotruncal Anatomy

Rastelli type C is particularly important in complete AVSD associated with tetralogy of Fallot (TOF) and other abnormalities involving ventriculoarterial alignment. Morphometric studies have demonstrated an association between extensive rightward bridging of the SBL and anterior/rightward displacement of the aortic root. [4]

In complete AVSD–TOF, the free-floating SBL may extend substantially into the right ventricle, while the VSD includes both inlet and outlet components. The surgeon must therefore understand not only the AVSD component but also the relationship among the SBL, malaligned outlet septum, aortic root, and prospective left ventricular outflow pathway. Classification as type C alone does not define this geometry.

6. Echocardiographic Assessment

Two-dimensional echocardiography generally permits accurate recognition of Rastelli morphology, particularly when several imaging planes are integrated. [7]

Subcostal and apical en-face imaging is particularly useful for determining the extent to which the SBL bridges the ventricular septum and for identifying chordal attachments. In type C, the central portion of the leaflet can be seen passing over the ventricular septum without tethering to its crest.

The examination should extend well beyond assigning a Rastelli type. Preoperative imaging should define:

• ventricular balance and common AV valve commitment;
• depth and anterior extension of the ventricular component;
• SBL and IBL chordal attachments;
• left and right mural leaflet dimensions;
• papillary-muscle position and spacing;
• preoperative left and right AV valve regurgitation;
• potential accessory valvar orifices;
• LVOT dimensions and the relationship of the SBL to the aortic root; and
• associated conotruncal, arch, or venous abnormalities. [7,8]

Three-dimensional echocardiography can be particularly informative when leaflet relationships or the mechanism of AV valve regurgitation cannot be adequately understood from conventional planes.

7. Surgical Implications

The absence of septal chordal attachment gives type C an important technical characteristic: there is no central chordal apparatus tethering the SBL directly to the VSD crest. This can provide considerable mobility during reconstruction. However, mobility should not be mistaken for simplicity.

During repair, the objective is to partition the common AV valve into competent left and right components while closing the ventricular and atrial communications without producing AV valve stenosis, residual regurgitation, or ventricular outflow obstruction.

The Rastelli classification does not mandate a particular repair. Two-patch, modified single-patch, and traditional single-patch approaches have all been used successfully in appropriately selected anatomy. The choice depends more directly on VSD depth, leaflet tissue, chordal relationships, ventricular balance, surgeon experience, and associated lesions than on the type C label itself.

With a two-patch repair, the ventricular patch is positioned beneath the common AV valve and the bridging leaflets are subsequently secured to its superior margin. In type C, the absence of central septal chordae generally permits relatively unrestricted placement of this patch-leaflet interface. Nevertheless, the partitioning line must preserve sufficient tissue and appropriate leaflet height on both sides.

In traditional single-patch techniques, the free-floating SBL may be divided to facilitate attachment to the patch. Leaflet division is not intrinsically required for type C anatomy, however, and contemporary techniques frequently preserve leaflet continuity. Studies evaluating bridging-leaflet division have emphasized that postoperative valve function depends on the entire valvar and subvalvar geometry rather than the Rastelli subtype alone. [11]

Particular attention is required to avoid:

1. Excessive rightward or leftward partitioning, producing an inadequate effective orifice on one side.
2. Distortion of the SBL, resulting in inadequate left AV valve coaptation.
3. Residual VSD, particularly beneath the bridging leaflets.
4. LVOT narrowing, especially when the patch or reconstructed leaflet is displaced toward the outflow tract.
5. Failure to recognize abnormal IBL chordae or accessory orifices, which are not predicted by the type C designation.

Late left AV valve regurgitation remains closely related to leaflet morphology, tissue quality, coaptation, and subvalvar geometry. [12]

8. Conduction System

As in other forms of AVSD, the atrioventricular node is displaced posteriorly and inferiorly relative to its normal position because the usual atrioventricular septal architecture and triangle of Koch are altered. The penetrating conduction axis subsequently courses along the posteroinferior region of the ventricular septal deficiency. [8–10]

This relationship is independent of whether the SBL is Rastelli type A, B, or C and remains a critical determinant of the VSD patch suture line. Histologic and morphologic studies indicate that the relationship of the inferior bridging leaflet to the ventricular septum is a particularly useful operative landmark for anticipating the site at which the conduction axis penetrates. [9,10]

Sutures along the posteroinferior ventricular margin therefore require deliberate placement away from the anticipated conduction axis.

9. Clinical Significance of the Classification

The practical value of recognizing Rastelli type C is not simply assigning a letter. It provides an immediate three-dimensional concept of the superior bridging leaflet–ventricular septum relationship: the leaflet bridges extensively into the right ventricle and lacks septal tethering.

At the same time, the limitations of the classification are important. Rastelli type does not describe ventricular balance, the IBL, mural leaflets, left-sided papillary muscles, degree of AV valve regurgitation, VSD depth, LVOT geometry, or associated lesions. These features frequently have greater direct impact on the repair than the classification itself.

Key Surgical Principles

• Recognize the defining anatomy: type C means a free-floating SBL without chordal attachment to the ventricular septal crest.
• Do not confuse type C with type B: anomalous RV papillary-muscle attachment is characteristic of type B, not the defining feature of type C.
• Inspect the entire common AV valve: IBL and chordal morphology are not predicted by the Rastelli subtype.
• Use the Rastelli label as a spatial roadmap, not an operative prescription.
• Preserve leaflet geometry and coaptation when partitioning the common AV valve.
• Assess both ventricular outflow tracts, particularly when conotruncal abnormalities coexist.
• Protect the posteroinferior conduction axis during VSD closure.
• Before leaving bypass, exclude significant AV valve regurgitation or stenosis, residual VSD, and LVOT/RVOT obstruction.

References

1. Rastelli GC, Kirklin JW, Titus JL. Anatomic observations on complete form of persistent common atrioventricular canal with special reference to atrioventricular valves. Mayo Clin Proc. 1966;41:296–308. PMID: 5932615.
2. Piccoli GP, Wilkinson JL, Macartney FJ, Gerlis LM, Anderson RH. Morphology and classification of complete atrioventricular defects. Br Heart J. 1979;42:633–639. doi:10.1136/hrt.42.6.633. PMID: 534580.
3. Anderson RH, Baker EJ, Ho SY, Rigby ML, Ebels T. The morphology and diagnosis of atrioventricular septal defects. Cardiol Young. 1991. doi:10.1017/S1047951100010362.
4. Suzuki K, Ho SY, Anderson RH, Becker AE, Neches WH, Devine WA, Tatsuno K, Mimori S. Morphometric analysis of atrioventricular septal defect with common valve orifice. J Am Coll Cardiol. 1998;31:217–223. doi:10.1016/S0735-1097(97)00456-7. PMID: 9426043.
5. Akiba T, Becker AE, Neirotti R, Tatsuno K. Valve morphology in complete atrioventricular septal defect: variability relevant to operation. Ann Thorac Surg. 1993;56:295–299. doi:10.1016/0003-4975(93)91163-H. PMID: 8347012.
6. Yamasaki T, Sanders SP, Toba S, Umezu K, Mayer JE Jr, Carreon CK. Systematic analysis of the atrioventricular canal in 129 heart specimens identified anatomic and microarchitectural advantages in Down syndrome. J Thorac Cardiovasc Surg. 2025;170:1206–1213.e4. doi:10.1016/j.jtcvs.2025.05.024. PMID: 40490215.
7. Nayak S, Kanakriyeh M, Varadarajan P. Echocardiographic assessment of atrioventricular canal defects. Echocardiography. 2020;37:2199–2210. doi:10.1111/echo.14961. PMID: 33368544.
8. Adachi I, Uemura H, McCarthy KP, Ho SY. Surgical anatomy of atrioventricular septal defect. Asian Cardiovasc Thorac Ann. 2008;16:497–502. doi:10.1177/021849230801600616. PMID: 18984764.
9. Feldt RH, DuShane JW, Titus JL. The atrioventricular conduction system in persistent common atrioventricular canal defect: correlations with electrocardiogram. Circulation. 1970. doi:10.1161/01.CIR.42.3.437. PMID: 5451229.
10. Seo JW, Zuberbuhler JR, Ho SY, Anderson RH. Surgical significance of morphological variations in the atrial septum in atrioventricular septal defect for determination of the site of penetration of the atrioventricular conduction axis. J Card Surg. 1992. doi:10.1111/j.1540-8191.1992.tb01022.x. PMID: 1482825.
11. Fortuna RS, Ashburn DA, Carias De Oliveira N, et al. Atrioventricular septal defects: effect of bridging leaflet division on early valve function. Ann Thorac Surg. 2004. doi:10.1016/S0003-4975(03)01066-X. PMID: 14992894.
12. Kanani M, Elliott M, Cook A, Juraszek AL, Devine W, Anderson RH. Late incompetence of the left atrioventricular valve after repair of atrioventricular septal defects: the morphologic perspective. J Thorac Cardiovasc Surg. 2006. doi:10.1016/j.jtcvs.2006.01.063. PMID: 16935121.

1. Definition

Rastelli type C is the form of complete atrioventricular septal defect (complete AVSD) in which the superior bridging leaflet (SBL) has no chordal attachment to the crest of the ventricular septum. The central portion of the leaflet therefore bridges freely across the ventricular septal defect (VSD), producing the characteristic “free-floating” superior bridging leaflet. This configuration represents the greatest degree of superior leaflet bridging in the classic Rastelli spectrum. The original classification was based primarily on the morphology and ventricular attachments of what was historically termed the common anterior leaflet. [1] (PubMed)

The Rastelli classification remains useful as a concise description of common atrioventricular valve morphology, but it should not be interpreted as a complete description of the valve. Modern surgical assessment must additionally define the inferior bridging leaflet, mural leaflets, papillary muscles and chordal architecture, ventricular balance, VSD geometry, and both ventricular outflow tracts. [2–5]

2. Core Morphology of Rastelli Type C

All complete AVSDs are characterized by a common atrioventricular junction guarded by a common atrioventricular valve, together with deficiencies of atrial and ventricular septation. The valve typically consists of superior and inferior bridging components and mural components extending toward each ventricular free wall. [2,3]

In Rastelli type C, the defining feature is the relationship between the SBL and ventricular septum:

• No supporting chordae insert into the ventricular septal crest.
• The SBL extends broadly across the plane of the ventricular septum and is free floating over the ventricular component of the defect.
• The ventricular communication beneath the leaflet is consequently generally unobstructed by septal chordal attachments.
• With increasing rightward bridging of the SBL, the separate right anterosuperior valvar component becomes progressively smaller. [2–4]

Morphologic studies support the concept that Rastelli types A, B, and C represent a spectrum of increasing bridging rather than three completely discrete valve designs. Piccoli and colleagues demonstrated that increasing extension of the anterior/superior bridging leaflet into the right ventricle was accompanied by progressive reduction in the size of the separate right anterior leaflet. [2]

The supplied schematic emphasizes the free-floating SBL, small right anterosuperior component, common AV junction, and displaced AV node.

Figure 1. Rastelli type C complete AVSD. The superior bridging leaflet extends across the ventricular septum without attachment to the septal crest. The absence of central tethering creates the characteristic free-floating appearance.

3. Subvalvar Apparatus: An Important Distinction From Type B

The subvalvar anatomy is particularly important when differentiating types B and C.

In Rastelli type B, the SBL extends farther into the right ventricle than in type A, but it remains supported by chordae that attach to an anomalous right ventricular papillary muscle, often located relatively apically or medially. In contrast, an anomalous apical papillary muscle is not the defining feature of Rastelli type C. In classic type C, the central SBL lacks septal or anomalous papillary-muscle attachment and is supported laterally from the papillary apparatus of the respective ventricles. [1–3]

Thus, the essential distinction is:

Type B = bridging leaflet tethered within the right ventricle by an anomalous papillary-muscle/chordal attachment.

Type C = bridging leaflet not tethered to the ventricular septum and truly free floating centrally.

Individual hearts may show intermediate or atypical chordal patterns, and the anatomy does not always fit perfectly into one category. Accordingly, the operative description should document the actual chordal insertions rather than relying exclusively on the Rastelli label.

The inferior bridging leaflet (IBL) also deserves independent assessment. Akiba and colleagues demonstrated considerable variability in its relationship to the septum, including direct, membranous, multiple-chordal, and nearly free-floating configurations, without a predictable relationship to the Rastelli classification of the superior leaflet. [5] Consequently, identification of a type C SBL does not imply that the inferior portion of the valve is similarly free floating.

4. Frequency and Association With Trisomy 21

Type C is generally the second major morphologic pattern after type A, whereas type B is consistently uncommon. The exact proportions vary substantially according to the population studied and the inclusion of unbalanced AVSD, heterotaxy, conotruncal abnormalities, and other complex anatomy.

In a morphometric study of 133 hearts with a common AV valve orifice, Suzuki and colleagues identified type A morphology in 56%, type C in 40%, and type B in only 4%. [4] (JACC) These figures illustrate why a single prevalence such as “35%” should be regarded as an approximate teaching value rather than a universal frequency.

Type C is also enriched among patients with trisomy 21, although reported proportions vary. A 2025 morphologic analysis of 129 unrepaired AV canal specimens found substantially more type C morphology in hearts from patients with Down syndrome: among classifiable complete defects, type C was identified in 40.5% of the Down syndrome group versus 13.5% of the non–Down syndrome group. [6] (DOI) Therefore, the association between trisomy 21 and type C is well supported, but a fixed figure such as “60% of patients with trisomy 21 have type C” is cohort dependent and should not be treated as a universal prevalence estimate.

5. Association With Conotruncal Anatomy

Rastelli type C is particularly important in complete AVSD associated with tetralogy of Fallot (TOF) and other abnormalities involving ventriculoarterial alignment. Morphometric studies have demonstrated an association between extensive rightward bridging of the SBL and anterior/rightward displacement of the aortic root. [4]

In complete AVSD–TOF, the free-floating SBL may extend substantially into the right ventricle, while the VSD includes both inlet and outlet components. The surgeon must therefore understand not only the AVSD component but also the relationship among the SBL, malaligned outlet septum, aortic root, and prospective left ventricular outflow pathway. Classification as type C alone does not define this geometry.

6. Echocardiographic Assessment

Two-dimensional echocardiography generally permits accurate recognition of Rastelli morphology, particularly when several imaging planes are integrated. [7]

Subcostal and apical en-face imaging is particularly useful for determining the extent to which the SBL bridges the ventricular septum and for identifying chordal attachments. In type C, the central portion of the leaflet can be seen passing over the ventricular septum without tethering to its crest.

The examination should extend well beyond assigning a Rastelli type. Preoperative imaging should define:

• ventricular balance and common AV valve commitment;
• depth and anterior extension of the ventricular component;
• SBL and IBL chordal attachments;
• left and right mural leaflet dimensions;
• papillary-muscle position and spacing;
• preoperative left and right AV valve regurgitation;
• potential accessory valvar orifices;
• LVOT dimensions and the relationship of the SBL to the aortic root; and
• associated conotruncal, arch, or venous abnormalities. [7,8]

Three-dimensional echocardiography can be particularly informative when leaflet relationships or the mechanism of AV valve regurgitation cannot be adequately understood from conventional planes.

7. Surgical Implications

The absence of septal chordal attachment gives type C an important technical characteristic: there is no central chordal apparatus tethering the SBL directly to the VSD crest. This can provide considerable mobility during reconstruction. However, mobility should not be mistaken for simplicity.

During repair, the objective is to partition the common AV valve into competent left and right components while closing the ventricular and atrial communications without producing AV valve stenosis, residual regurgitation, or ventricular outflow obstruction.

The Rastelli classification does not mandate a particular repair. Two-patch, modified single-patch, and traditional single-patch approaches have all been used successfully in appropriately selected anatomy. The choice depends more directly on VSD depth, leaflet tissue, chordal relationships, ventricular balance, surgeon experience, and associated lesions than on the type C label itself.

With a two-patch repair, the ventricular patch is positioned beneath the common AV valve and the bridging leaflets are subsequently secured to its superior margin. In type C, the absence of central septal chordae generally permits relatively unrestricted placement of this patch-leaflet interface. Nevertheless, the partitioning line must preserve sufficient tissue and appropriate leaflet height on both sides.

In traditional single-patch techniques, the free-floating SBL may be divided to facilitate attachment to the patch. Leaflet division is not intrinsically required for type C anatomy, however, and contemporary techniques frequently preserve leaflet continuity. Studies evaluating bridging-leaflet division have emphasized that postoperative valve function depends on the entire valvar and subvalvar geometry rather than the Rastelli subtype alone. [11]

Particular attention is required to avoid:

1. Excessive rightward or leftward partitioning, producing an inadequate effective orifice on one side.
2. Distortion of the SBL, resulting in inadequate left AV valve coaptation.
3. Residual VSD, particularly beneath the bridging leaflets.
4. LVOT narrowing, especially when the patch or reconstructed leaflet is displaced toward the outflow tract.
5. Failure to recognize abnormal IBL chordae or accessory orifices, which are not predicted by the type C designation.

Late left AV valve regurgitation remains closely related to leaflet morphology, tissue quality, coaptation, and subvalvar geometry. [12]

8. Conduction System

As in other forms of AVSD, the atrioventricular node is displaced posteriorly and inferiorly relative to its normal position because the usual atrioventricular septal architecture and triangle of Koch are altered. The penetrating conduction axis subsequently courses along the posteroinferior region of the ventricular septal deficiency. [8–10]

This relationship is independent of whether the SBL is Rastelli type A, B, or C and remains a critical determinant of the VSD patch suture line. Histologic and morphologic studies indicate that the relationship of the inferior bridging leaflet to the ventricular septum is a particularly useful operative landmark for anticipating the site at which the conduction axis penetrates. [9,10]

Sutures along the posteroinferior ventricular margin therefore require deliberate placement away from the anticipated conduction axis.

9. Clinical Significance of the Classification

The practical value of recognizing Rastelli type C is not simply assigning a letter. It provides an immediate three-dimensional concept of the superior bridging leaflet–ventricular septum relationship: the leaflet bridges extensively into the right ventricle and lacks septal tethering.

At the same time, the limitations of the classification are important. Rastelli type does not describe ventricular balance, the IBL, mural leaflets, left-sided papillary muscles, degree of AV valve regurgitation, VSD depth, LVOT geometry, or associated lesions. These features frequently have greater direct impact on the repair than the classification itself.

Key Surgical Principles

• Recognize the defining anatomy: type C means a free-floating SBL without chordal attachment to the ventricular septal crest.
• Do not confuse type C with type B: anomalous RV papillary-muscle attachment is characteristic of type B, not the defining feature of type C.
• Inspect the entire common AV valve: IBL and chordal morphology are not predicted by the Rastelli subtype.
• Use the Rastelli label as a spatial roadmap, not an operative prescription.
• Preserve leaflet geometry and coaptation when partitioning the common AV valve.
• Assess both ventricular outflow tracts, particularly when conotruncal abnormalities coexist.
• Protect the posteroinferior conduction axis during VSD closure.
• Before leaving bypass, exclude significant AV valve regurgitation or stenosis, residual VSD, and LVOT/RVOT obstruction.

References

1. Rastelli GC, Kirklin JW, Titus JL. Anatomic observations on complete form of persistent common atrioventricular canal with special reference to atrioventricular valves. Mayo Clin Proc. 1966;41:296–308. PMID: 5932615.
2. Piccoli GP, Wilkinson JL, Macartney FJ, Gerlis LM, Anderson RH. Morphology and classification of complete atrioventricular defects. Br Heart J. 1979;42:633–639. doi:10.1136/hrt.42.6.633. PMID: 534580.
3. Anderson RH, Baker EJ, Ho SY, Rigby ML, Ebels T. The morphology and diagnosis of atrioventricular septal defects. Cardiol Young. 1991. doi:10.1017/S1047951100010362.
4. Suzuki K, Ho SY, Anderson RH, Becker AE, Neches WH, Devine WA, Tatsuno K, Mimori S. Morphometric analysis of atrioventricular septal defect with common valve orifice. J Am Coll Cardiol. 1998;31:217–223. doi:10.1016/S0735-1097(97)00456-7. PMID: 9426043.
5. Akiba T, Becker AE, Neirotti R, Tatsuno K. Valve morphology in complete atrioventricular septal defect: variability relevant to operation. Ann Thorac Surg. 1993;56:295–299. doi:10.1016/0003-4975(93)91163-H. PMID: 8347012.
6. Yamasaki T, Sanders SP, Toba S, Umezu K, Mayer JE Jr, Carreon CK. Systematic analysis of the atrioventricular canal in 129 heart specimens identified anatomic and microarchitectural advantages in Down syndrome. J Thorac Cardiovasc Surg. 2025;170:1206–1213.e4. doi:10.1016/j.jtcvs.2025.05.024. PMID: 40490215.
7. Nayak S, Kanakriyeh M, Varadarajan P. Echocardiographic assessment of atrioventricular canal defects. Echocardiography. 2020;37:2199–2210. doi:10.1111/echo.14961. PMID: 33368544.
8. Adachi I, Uemura H, McCarthy KP, Ho SY. Surgical anatomy of atrioventricular septal defect. Asian Cardiovasc Thorac Ann. 2008;16:497–502. doi:10.1177/021849230801600616. PMID: 18984764.
9. Feldt RH, DuShane JW, Titus JL. The atrioventricular conduction system in persistent common atrioventricular canal defect: correlations with electrocardiogram. Circulation. 1970. doi:10.1161/01.CIR.42.3.437. PMID: 5451229.
10. Seo JW, Zuberbuhler JR, Ho SY, Anderson RH. Surgical significance of morphological variations in the atrial septum in atrioventricular septal defect for determination of the site of penetration of the atrioventricular conduction axis. J Card Surg. 1992. doi:10.1111/j.1540-8191.1992.tb01022.x. PMID: 1482825.
11. Fortuna RS, Ashburn DA, Carias De Oliveira N, et al. Atrioventricular septal defects: effect of bridging leaflet division on early valve function. Ann Thorac Surg. 2004. doi:10.1016/S0003-4975(03)01066-X. PMID: 14992894.
12. Kanani M, Elliott M, Cook A, Juraszek AL, Devine W, Anderson RH. Late incompetence of the left atrioventricular valve after repair of atrioventricular septal defects: the morphologic perspective. J Thorac Cardiovasc Surg. 2006. doi:10.1016/j.jtcvs.2006.01.063. PMID: 16935121.