Positional Classification

Until 1994, JAA was classified positionally:

• 1.
  

  left JAA , meaning that both atrial appendages lie to the left of the vascular pedicle (aorta and pulmonary artery) (see Fig. 10.2 ) ; and

  
  
• 2.
  

  right JAA, indicating that both atrial appendages lie to the right of the vascular pedicle (see Fig. 10.1 ).

Morphologic and positional classification ^, asks three questions of the diagnostician:

• 1.
  

  Morphologically, which appendage is malpositioned relative to the great arteries? Is it the morphologically right atrial appendage that is on the wrong side of the vascular pedicle, as in Fig. 10.2 ? Or is it the morphologically left atrial appendage that is on the wrong side of the vascular pedicle, as in Fig. 10.1 ?

  
  
• 2.
  

  Positionally what is the sidedness of the abnormally located atrial appendage that results in JAA? Is it malpositioned to the left of the great arteries? Or is it malpositioned to the right of the great arteries?

  
  
• 3.
  

  What is the atrial situs of the patient? Is it situs solitus (usual or normal pattern of atrial organization)? Or is it situs inversus (the mirror-image pattern of atrial organization)? As will be seen, the type of atrial situs helps to make the JAA understandable.

Anatomic Types of Juxtaposition of the Atrial Appendages

There are four morphologic and positional anatomic types of JAA ( Fig. 10.3 ):

• 1.
  

  Malposition of the morphologically right atrial appendage (RAA) to the left of the vascular pedicle in atrial situs solitus (see Fig. 10.2 ). This is the classic type of malposition of the RAA to the left of the vascular pedicle, resulting in typical left-sided JAA, that occurred in 34 of our 35 cases with malposition of the RAA (97%).

  
  
• 2.
  

  Malposition of the RAA to the right of the vascular pedicle in atrial situs inversus ( Fig. 10.4 ). This is the rare form of malposition of the RAA, resulting in right-sided JAA, that we observed in only 1 of these 35 patients (3%).

  
  

  
  

  
  

  

  
  

  
  

  (A) Right-sided juxtaposition of the atrial appendages (JAA) with malposition of the right atrial appendage (RAA) in atrial situs inversus, anterior view. The RAA is juxtaposed and superior to the nonmalposed left atrial appendage (LAA). This 7-month-old girl had double-outlet right ventricle (DORV) {I,D,D} with dextrocardia, visceral heterotaxy, and asplenia. This was the first photographically documented case of JAA with malposition of the RAA in atrial situs inversus. The ascending aorta (Ao) lies to the right of the dilated main pulmonary artery (MPA). IVC, Left-sided inferior vena cava that returned to the left-sided right atrium (RA); 1, left common carotid artery; 2, right common carotid artery; 3, aberrant right subclavian artery, anastomosed to the right pulmonary artery; 4, left subclavian artery. Anastomosis of the ascending Ao to the MPA resulted in marked dilatation of the MPA. (B). Interior of the left-sided morphologically RA showing that the IVC returns to this atrium, as do the left superior vena cava (LSVC) and the coronary sinus (CoS). The ostium of the CoS is enlarged because it receives a persistent right SVC. A large ostium secundum type of atrial septal defect (solid white triangle) is seen above a deficient septum primum (AS). The morphologically RV is hypoplastic and superior to the morphologically left ventricle (LV). The ascending Ao is anterior to the dilated MPA.(C) Interior of the underdeveloped and right-handed RV, showing the widely patent outflow tract to the anterior and right-sided Ao, and the stenotic outflow tract leading to the pulmonary artery (PA Out). This patient had a bilateral conus (subaortic and subpulmonary). The pulmonary infundibular stenosis was produced both by the hypertrophied infundibular septum and by the hypertrophied subpulmonary infundibular free wall. The broad triangular RAA is seen sitting on top of the finger-like LAA. The tricuspid valve (TV) lies to the right of both great arterial outflow tracts, typical of a right-handed D-loop RV. There were concordant atrioventricular alignments (RA opening into RV, and LA opening into LV), despite the discordant atrial and ventricular situs: DORV { I,D, D}. Incongruence of alignment and situs concordance or discordance is one of the features of right-sided JAA. Note that the JRAA syndrome is present: small right-sided RV, and complex conotruncal anomaly (DORV {I,D,D} with bilateral conus and severe pulmonary outflow tract stenosis). There is left shift of the ventricles and great arteries relative to the inverted atria (as in Fig. 10.3 , diagram 2), which explains why there is JAA, why the JAA is right-sided, and why it is the RAA that is malpositioned relative to the great arteries.Despite the fact that this patient had visceral heterotaxy with asplenia, the visceral situs was not undiagnosable or isomeric, as is indicated by the left-sided IVC. The atria and the atrial appendages were clearly inverted (“right isomerism” not being present). In the classification of the anatomic types of JAA (see Fig. 10.3 ), situs ambiguus (heterotaxy, or “isomerism”) was not included for several reasons: (1) Situs ambiguus is not a specific anatomic type of situs; instead, it is undiagnosed (or undiagnosable, or scrambled) situs solitus or situs inversus. (2) The concept of atrial, or atrial appendage, isomerism is an error (see Chapter 29 ). (3) The anatomic classification of JAA (and of all other anomalies) should be as simple as possible, consistent with accuracy (Occam’s razor, or the principle of economy or parsimony).

  
  

  Reproduced with permission from Van Praagh S, O’Sullivan J, Brili S, Van Praagh R. Juxtaposition of the morphologically right atrial appendage in solitus and inversus atria: A study of 35 postmortem cases. Am Heart J. 1996;132;382.

  
  
  
  
• 3.
  

  Malposition of the left atrial appendage (LAA) to the right of the vascular pedicle in atrial situs solitus ( Fig. 10.5 ). This was the more frequent form of malposition of the LAA, which resulted in right-sided JAA, and was found in 16 of these 18 cases (89%).

  
  

  
  

  
  

  

  
  

  
  

  (A) Right-sided juxtaposition of the atrial appendages (JAA), in visceroatrial situs solitus, with malposition of the left atrial appendage (LAA ) relative to the great arteries, similar to Fig. 10.3 , diagram 3. Anteroposterior view showing that the LAA is beside and superior to the right atrial appendage (RAA). The morphologically right ventricle (RV) is relatively small and superior to the morphologically left ventricle (LV). The aortic orifice of a large patent ductus arteriosus (PDA) is also seen. (B) Posterior view of opened atria, mitral valve (MV), and LV. The septum primum is absent. The common atrium is present. It is possible to see into the RAA and the LAA. The inferior vena cava (IVC) and the superior vena cava (SVC) connect normally with the right atrium (RA). The RA is aligned with an opens into the large LV via a large MV. The left atrium (LA) is aligned with an opens into a small RV (not seen in this view) via a stenotic tricuspid valve (solid white arrowhead). Thus, there is atrioventricular (AV) alignment discordance. (C) Interior of hypoplastic right-handed RV is seen. The inlet of the RV and the stenotic tricuspid valve (TV) lie to the right of the RV outflow tract, the RV being right-handed. Both the aortic valve (AoV) and the pulmonary valve (PV) arise above the RV; that is, double-outlet right ventricle (DORV) is present. The conal septum (CS) is extremely hypoplastic; pulmonary outflow tract stenosis is present; and there is AoV-TV direct fibrous continuity. The AoV lies to the right of the PV, and a stenotic muscular subpulmonary conus (with no subaortic conal free wall conus) is present. In summary, this 4-day-old boy with mesocardia had DORV {S,D,D} with AV alignment discordance. There was incongruence of AV alignment and situs concordance or discordance: discordant AV alignments with concordant AV situs. This patient also had visceral heterotaxy with hyposplenia (spleen smaller than normal, i.e., hypoplastic, as is often found with polysplenia which also has multiple small splenuli). The ventricles and great arteries are left shifted relative to the solitus atria and the atrioventricular valves (see Fig. 10.3 , diagram 3). S2° septum secundum.

  
  

  Reproduced with permission from Van Praagh S, O’Sullivan J, Brili S, Van Praagh R. Juxtaposition of the morphologically left atrial appendage in solitus and inversus atria: A study of 18 postmortem cases. Am Heart J. 1996;132:391.

  
  
  
  
• 4.
  

  Malposition of the LAA to the left of the vascular pedicle in atrial situs inversus ( Fig. 10.6 ). This was the rare form of malposition of the LAA, found in only 2 of these 18 cases (11%).

  
  

  
  

  
  

  

  
  

  
  

  (A) Left-sided juxtaposition of the atrial appendages (JAA) in visceroatrial situs inversus with malposition of the morphologically left atrial appendage (LAA) to the left of both great arteries, anterior view, similar to Fig. 10.3 , diagram 4. The LAA is beside and superior to the morphologically right atrial appendage (RAA). The morphologically right ventricle (RV) is right-sided and superior relative to the morphologically left ventricle (LV). This 2 9/12-year-old boy had dextrocardia. (B) Opened morphologically left atrium, right-sided, that is, LA (R), and opened RV, right-sided. The septum primum (Sept I) lies to the right of the superior limbic band of septum secundum (unlabeled), as is characteristic of atrial situs inversus. Sept I is deficient, resulting in an abnormally large ostium secundum above the septum primum and below the superior limbic band of septum secundum. The septum primum also displays multiple (at least 7) fenestrations. Hence, this patient has multiple ostium secundum type atrial septal defects (a valve incompetent patent foramen ovale with an excessively large ostium secundum, plus multiple fenestrations in the deficient septum primum). This patient also has a completely common atrioventricular canal, type C, that is, CCAVC (C). Both great arteries arise from a bilateral conus (subaortic and subpulmonary) above the RV. The aortic valve (AoV) is well seen because the aortic outflow tract is widely patent, whereas the pulmonary valve is not well visualized because the pulmonary outflow tract (PA Out) is tightly stenotic . To summarize, this patient has left-sided JAA in visceroatrial situs inversus with malposition of the LAA relative to the great arteries (as in Fig. 10.3 , diagram 4), and double-outlet right ventricle (DORV) {I,D,D} with multiple secundum ASDs, CCAVC type C, small right-sided RV, bilateral conus, and severe pulmonary outflow tract stenosis. The D-loop ventricles and great arteries are right shifted relative to the inversus atria (see Fig. 10.3 , diagram 4).

  
  

  Reproduced with permission from Van Praagh S, O’Sullivan J, Brili S, Van Praagh R. Juxtaposition of the morphologically left atrial appendage in solitus and inversus atria: A study of 18 postmortem cases. Am Heart J. 1996;132:391.

  
  

Diagrams of the Four Anatomic Types of Juxtaposition of the Atrial Appendages (JAA).

JAA with malposition of the morphologically right atrial appendage (JRAA) almost always had situs solitus of the viscera and atria with the right atrial appendage (RAA) lying to the right of the left atrial appendage (LAA), with both atrial appendages lying to the left of both great arteries (97%). However, in a few cases with JRAA, there was situs inversus of the viscera and atria, and in all of these patients both atrial appendages lay to the right of both great arteries (3%). The arrows indicate the direction of malposition of the ventricular and infundibuloarterial segments relative to the atrial and the atrioventricular (AV) canal segments. In diagram 1, there is right shift of the bulboventricular loop relative to the atria and the AV canal. In diagram 2 , there is left shift of the ventricles and great arteries relative to the atria and the AV valves. JRAA often had the JRAA syndrome (see Table 10.2 ). JAA with malposition of the morphologically left atrial appendage (JLAA) also usually had situs solitus of the viscera and atria (89%, in diagram 3 ), but a minority had situs inversus of the viscera and atria (11%, in diagram 4 ). The directions of malposition of the bulboventricular loop relative to the atria and the AV canal (right shift or left shift) are indicated by arrows. Patients with JLAA often had the JLAA syndrome (see Table 10.2 ). Analysis of JAA in terms of which atrial appendage is malpositioned relative to the vascular pedicle is helpful because such morphologic analysis correlates with the previously mentioned JRAA (diagrams 1 and 2) and JLAA (diagrams 3 and 4 ) syndromes (see Table 10.2 ). ^, Positional analysis of JAA is also illuminating. Right shift of the ventricles and great arteries relative to the atria and AV valves (diagrams 1 and 4 ) results in (or is associated with) left-sided JAA both in visceroatrial situs solitus (diagram 1 ) and in visceroatrial situs inversus (diagram 4 ). But in situs solitus, malposition of the RAA occurs, whereas in situs inversus, malposition of the LAA occurs (compare diagrams 1 and 4 ). So the JRAA syndrome applies in situs solitus, and the JLAA syndrome applies in situs inversus. Conversely, left shift of the ventricles and great arteries relative to the atria and the AV valves leads to right-sided JAA both in situs solitus (diagram 3 ) and in situs inversus (diagram 2 ), but the JLAA syndrome applies in situs solitus, and the JRAA syndrome is relevant in situs inversus. Thus, JAA should be understood both positionally and morphologically. ^, Ao, Aorta; LA, morphologically left atrium; LAA, morphologically left atrial appendage; PA, pulmonary artery; RA, morphologically right atrium.

From Van Praagh S, O’Sullivan J, Brili S, Van Praagh R. Juxtaposition of the morphologically right atrial appendage in solitus and inversus atria: A study of 35 postmortem cases. Am Heart J. 1996;132:382-390; and Van Praagh S, O’Sullivan J, Brili S, Van Praagh R. Juxtaposition of the morphologically left atrial appendage in solitus and inversus atria: A study of 18 postmortem cases. Am Heart J. 1996;132:391–402; with permission.

Thus, each atrial appendage was malpositioned in only one way in each type of atrial situs (see Fig. 10.3 ):

• 1.
  

  In visceroatrial situs solitus, the RAA can be malpositioned in only one way: to the left of the vascular pedicle (see Fig. 10.2 ).

  
  
• 2.
  

  In visceroatrial situs inversus, the left-sided RAA can be malpositioned in only one way: to the right of the vascular pedicle (see Fig. 10.4 ).

The same is true of the LAA:

• 1.
  

  In visceroatrial situs solitus, the LAA can be malpositioned in only one way: to the right of the vascular pedicle (see Fig. 10.1 and 10.5 ).

  
  
• 2.
  

  In visceroatrial situs inversus, the LAA can be malpositioned in only one way: to the left of the vascular pedicle (see Fig. 10.6 ).

The foregoing is why there are four anatomic types of JAA, based on their morphologic and positional anatomy (see Fig. 10.3 ). The frequencies of these four anatomic types are also included in this diagram (see Fig. 10.3 ), based on our two most recent studies. ^,

One may ask why did we not include atrial situs ambiguus with visceroatrial heterotaxy and asplenia in the morphologic and positional classification of JAA (see Fig. 10.3 ). The answer is that we did not find any such cases in our data. ^, In addition, from a logical standpoint, atrial situs ambiguus is either undiagnosed or undiagnosable atrial situs solitus or atrial situs inversus. Consequently, no type of atrial situs has been omitted from Fig. 10.3 because atrial situs ambiguus is not a specific, third anatomic type of atrial situs, to the best of our present understanding.

How can one understand the frequencies of each anatomic type of JAA (see Fig. 10.3 )?

• Q.
  

  Why is JAA, involving malposition of the RAA, typically left-sided JAA (97%) rather than right-sided JAA (3%)?

  
  
  
  
  • A.
    

    Because atrial situs solitus is so much more common than atrial situs inversus. Atrial situs solitus is estimated to be 5000 to 15,000 times more frequent than atrial situs inversus. (See Chapter 3 for discussion of dextrocardia and other cardiac malpositions.)

  
  
  
  
• Q.
  

  Why is JAA involving malposition of the LAA so much more frequently right-sided (89%) than left-sided (11%)?

  
  
  
  
  • A.
    

    Again, because atrial situs solitus is so much more frequent than atrial situs inversus.

  
  
  
  
• Q.
  

  Is it possible to diagnose the atrial situs when visceral heterotaxy with asplenia coexists?

  
  
  
  
  • A.
    

    Yes. In some cases this can be done with confidence (see Fig. 10.3 ) (see Chapter 29 ).

  
  
  
  
• Q.
  

  Why is it clinically and surgically important to diagnose the morphologic anatomic identity of the malpositioned atrial appendage in JAA?

  
  
  
  
  • A.
    

    Because JAA involving malposition of the RAA (left-sided malposition in situs solitus and right-sided malposition in situs inversus) and JAA involving malposition of the LAA (right-sided in situs solitus and left-sided in situs inversus) constitute distinctive and largely opposite syndromes ( Table 10.2 ). ^,

    
    
    
    

    TABLE 10.2

    
    

    JAA With Malposition of the RAA Compared With JAA With Malposition of the LAA ^,

    
    

    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    

    	MRAA (n = 35)		MLAA (n = 18)
    Associated Malformations	No.	%	No.	%	p Value
    1. Right atrial outlet obstruction (tricuspid atresia, stenosis, hypoplasia)	21	60	0	0	<.001
    2. RV hypoplasia or absence	26	74	5 ∗	28	<.01
    3. Left atrial outlet obstruction (mitral atresia, stenosis, hypoplasia or left-sided tricuspid stenosis)	0	0	12	69	<.001
    4. Common atrioventricular valve	0	0	5	28	<.01
    5. Abnormal conus with TGA, DORV, or ACM	35	100	4	22	<.01
    6. Aortic or subaortic stenosis or atresia	1	3	7	39	<.01
    7. Heterotaxy with asplenia, polysplenia, or hyposplenia	1	3	5	28	<.05

     
    

    ACM , Anatomically right ventricle; JAA , juxtaposition of the atrial appendages; LAA , morphologically left atrial appendage; LV , morphologically left ventricle; MLAA , morphologically left atrial appendage; MRAA , morphologically right atrial appendage; RAA , (morphologically) right atrial appendage; RV , (morphologically) right ventricle; TGA , transposition of the great arteries.

    
    

    ∗ Double-inlet LV was present in 3 of these 5 cases, and in all 5 the hypoplastic or absent RV sinus was associated with stenosis of the left, not the right, atrial outlet. These cases were hemodynamically and anatomically very different from cases with RV hypoplasia or absence and JAA with malposition of the RAA.

    
    

  
  

The Syndrome of JAA With Malposition of the RAA

The syndrome of JAAs with malposition of the RAA (JRAA) to the left or right of the vascular pedicle is characterized by multilevel right heart obstruction (see Table 10.2 ). Specifically there was right atrial outflow obstruction, that is, tricuspid atresia or stenosis, or hypoplasia in 21 of 35 cases (60%); right ventricular hypoplasia or absence in 26 of 35 cases (74%); and an abnormal conus with transposition of the great arteries (TGA), DORV, or anatomically corrected malposition of the great arteries in 35 of 35 cases (100%). All of these features of JAA with malposition of the RAA were statistically significantly different from those associated with JAA and malposition of the LAA (see Table 10.2 ).

In somewhat greater detail, the findings in JAA with malposition of the RAA, for convenient brevity called JRAA, may be summarized as follows:

• 
  

  Sex: Males-to-females = 19 of 15 (1.27/1). The sex was not recorded in 1 case.

  
  
• 
  

  Age at Death: Median, 5.5 months; mean, 41.7 months; range 22-week fetus to 19.5 years.

  
  
• 
  

  Cardiac Malposition: Dextrocardia, 5 of 35 (14.3%); and mesocardia, 7 of 35 (20%). Total cardiac malpositions, 12 of 35 (34%).

  
  
• 
  

  Persistent Left Superior Vena Cava: 11 of 34 with atrial situs solitus (32.35%) and 1 of 1 with atrial situs inversus (100%). Total prevalence, 12 of 35 (34.29%), which was significantly higher than the frequency of persistent LSVC in a control series (10 of 127, 7.9% p < .001).

  
  
• 
  

  Eustachian Valve of the Inferior Vena Cava and Thebesian Valve of the Coronary Sinus: Absent in 24 of 33 cases (73%).

  
  
• 
  

  Atrial Septum: Intact in only 1 of 35 cases (3%). In 34 of 35 patients (97%), a secundum ASD, a widely patent foramen ovale, or a resected atrial septum was found.

  
  
• 
  

  RV Sinus: Hypoplastic or absent in 26 of 35 (74%).

  
  
• 
  

  Tricuspid Valve: Tricuspid atresia, 11 of 35 (31.4%); tricuspid stenosis, 7 of 35 (20%); tricuspid hypoplasia, 3 of 35 (8.6%); myoxomatous tricuspid valve, 1 of 35 (2.9%); abnormal attachments to ventricular septum or abnormal chordae tendinae, 3 of 35 (8.6%). The tricuspid valve was normal in 10 of 35 (28.6%). Hence, the tricuspid valve was abnormally formed in 71%.

  
  
• 
  

  Mitral Valve: By contrast, with JAA and malposition of the RAA, the mitral valve was usually normally formed: 29 of 35 cases (82.9%). However, abnormalities of the mitral valve were found in 6 of 35 patients (17.1%): myxomatous mitral valve, 3 of 35 (8.6%); abnormal chordal attachments, 1 of 35 (2.9%); thick nodular leaflets, 1 of 35 (2.9%); and mitral regurgitation, 1 of 35 (2.9%).

  
  
• 
  

  Ventricular Situs: D-loop ventricles in 35 of 35 cases (100%).

  
  
• 
  

  Atrioventricular Alignments and Situs: AV alignment concordance was present in all (35/35 cases, 100%). The right atrium (RA) was aligned with and opened into the RV, and the left atrium (LA) was aligned with and opened into the LV in all patients. However, there was AV situs concordance in only 34 of 35 cases (97%): { S,D, D}.

In one rare patient, there was AV situs discordance with AV alignment concordance. This patient had DORV {I,D,D} with visceral heterotaxy and asplenia (see Fig. 10.4 ). The AV situs was discordant: {I,D,-}. But the AV alignments were concordant: the left-sided RA was aligned with and opened into the right-sided RV, and the right-sided LA was aligned with and opened into the left-sided LV.

As this rare case illustrates, there are two different types of AV concordance and discordance: (1) alignment concordance/discordance (which atrium opens into which ventricle?) and (2) situs concordance/discordance (i.e., is the situs of the ventricles the same as or different from the situs of the atria?). Almost always, alignment concordance or discordance and situs concordance or discordance are the same; that is, alignment and situs concordance or discordance are congruent. But JAA is the exception. ^{, ,} AV alignment and situs concordance/discordance can be opposites (incongruent), as in this rare case (see Fig. 10.4 ) and others ( Fig. 10.7 ).

(A) Right-sided juxtaposition of the atrial appendages (JAA) with situs solitus of the viscera and atria, and right-sided malposition of the morphologically left atrial appendage (LAA) relative to the great arteries, as in Fig. 10.3 , diagram 3, anterior view of heart and lungs. The LAA is beside and superior to the morphologically right atrial appendage (RAA). The morphologically right ventricle (RV) is left-sided and superior relative to the morphologically left ventricle (LV). A rather small ascending aorta (Ao) lies to the right of a larger main pulmonary artery (MPA). The left innominate vein (Lt Innom V) is normally located. (B) Opened morphologically right atrium (RA), right lateral view. The inferior vena cava (IVC) and the superior vena cava (SVC) connect normally with the RA. The RAA points anteriorly. The tricuspid valve (TV) is of good size and notably low. (C) The right-sided RA is aligned with and opens into the left-sided RV via the low lying TV. Note the typically coarse RV trabeculations, the rightward ventricular septum (VS), and the leftward ventricular free wall (FW). This is a left-handed (inverted) RV, typical of L-loop ventricles. The widely patent outflow tract to the leftward MPA and the narrowed outflow tract leading to the rightward aorta (To Ao) are seen. There is a bilateral conus, both subpulmonary (not stenotic) and subaortic (stenotic), with no semilunar-atrioventricular fibrous continuity. The aortic outflow tract stenosis occurs between the conal septum to the left and the subaortic conal free wall to the right. Both great arteries arise above the RV; that is, double-outlet right ventricle (DORV) is present: DORV {S,L,D}. The ventricular septal defect (VSD) is subaortic. (D) The opened morphologically left atrium (LA) is viewed from the front and above. A secundum type of atrial septal defect (ASD II) is seen. The left-sided LA is aligned with and opens into a right-sided LV via the mitral valve (MV). Note the smaller ascending Ao and the larger MPA arising to the left of the LA. (E) The left-sided LA opens into a right-sided LV via quite a high MV. (F) The LV is right-handed, typical of L-loop ventricles (the LV septal surface is leftward and the LV free wall is rightward). The VSD is partially plugged by left-sided TV tissue. The muscular subaortic conus and aortic valve (AoV) have been opened to facilitate photography. The only outlet from the LV was the VSD. To summarize, this was a patient with right-sided JAA in visceroatrial situs solitus with malposition of the LAA relative to the great arteries. In addition, this patient had DORV {S,L,D} with atrioventricular (AV) alignment concordance, crisscross AV relations with inferior TV and superior MV, ASD II, subaortic VSD, bilateral conus, aortic outflow tract stenosis, and mild to moderate hypoplasia of the ascending Ao and aortic arch. Rare features include incongruence of AV alignments (concordant) and AV situs (discordant); and crisscross AV relations with inferior TV and superior MV. The ventricles and great arteries are left-shifted relative to the solitus atria (see Fig. 10.3 , diagram 3). (This anomaly was originally published in 1970 by Wagner, Alday, and Vlad as their Case 6.)

Reproduced with permission from Van Praagh R, David I, Gordon D, Wright GB, Van Praagh S. Ventricular diagnosis and designation. In: Godman MJ, ed. Pediatric Cardiology. Vol. 4. London: World Congress London; 1980; Edinburgh: Churchill Livingstone, 1981;153.

Why is incongruence of AV alignment concordance or discordance and AV situs concordance or discordance a feature of JAA (and of no other form of congenital heart disease, to our knowledge)? Our hypothesis is as follows: In complex congenital heart disease, the atria usually are not malpositioned; they are the “straight men.” Usually only the ventricles are malpositioned; they are the “professional contortionists.” Typically therefore, there is only one variable—the position of the ventricles. But with JAA, there are two variables. The positions of the ventricles and of the atria both are abnormal—making possible rare and surprising AV alignments that one would not expect in view of the atrial and the ventricular situs.

Dr. John Kirklin once asked me whether it is possible for the AV alignments to predict the ventricular situs wrongly. We all now know that the answer is yes. As in this rare case (see Fig. 10.4 ) of DORV {I,D,D} with AV alignment concordance, the fact that the atria were in situs inversus and that there were concordant AV alignments might well suggest that the ventricles were of the L-loop or inverted type. However, D-loop (noninverted) ventricles were found. Incongruity of alignment and situs concordance/discordance has been known and documented since 1970. ^{, ,} This is one reason why it is necessary to diagnose both the type of AV alignment (concordant, discordant, double-inlet LV, double-inlet RV, etc.) and the type of ventricular situs (D-loop/L-loop ventricles) because the AV alignments can predict the wrong type and ventricular loop or the AV alignments may be nonpredictive, as in double-inlet LV/RV and as in atrial situs ambiguus.

Why can the AV alignments be wrongly predictive or nonpredictive concerning the ventricular situs (D-/L-loop)? Because the AV alignments and the ventricular situs are two different variables. The only diagnostic method that always works accurately is to diagnose each variable specifically: What are the AV alignments (concordant, discordant, other)? What is the ventricular situs (D-loop/L-loop)?

Anderson, Smith, and Wilkinson have recognized the incongruity phenomenon, which they have called disharmony between AV connections and segmental combinations. They also pointed out that such cases are unusual variants of “crisscross” hearts. In our case (see Fig. 10.4 ), for example, the left-sided RA opens into the right-sided RV, and the right-sided LA opens into the left-sided LV. The AV inflow tracts seem to cross each other, instead of normally being approximately parallel and uncrossed. The appearance of crisscross AV relations is produced by a major malposition of the ventricles. The AV inflow tracts really do not intersect and physically cross each other. Nonetheless the appearance (or illusion) of crisscross AV relations is useful as a sign of ventricular malposition. (Crisscross AV relations are discussed and illustrated in Chapter 18 .)

This rare patient (see Fig. 10.4 ) was the first reported case of JAA with right-sided malposition of the RAA in atrial situs inversus.

Incongruence of AV alignment concordance or discordance relative to AV situs concordance or LA appendage (LLA) discordance almost always has occurred with JAA associated with malposition of the LAA , ^{, ,} and seldom with JAA and malposition of the RA appendage (RAA). Why this difference? We do not know. It should be added that JAA with incongruence of AV alignments and situs is rare, the numbers are small, and judgment should therefore be deferred, awaiting more data.

Ventricular Septum

In JAA with malposition of the RAA, a ventral septal defect (VSD) was present in 32 of 35 patients (91%). The anatomic types of VSD that were present are summarized in Table 10.3 .

TABLE 10.3

Only gold members can continue reading. Log In or Register to continue

Share this:

• Click to share on Twitter (Opens in new window)
• Click to share on Facebook (Opens in new window)

Related

Related posts:

1. Assessment of Ventricular Function Using the Pressure-Volume Relationship
2. Morphologic Anatomy
3. Absence of the Subpulmonary Infundibulum With Its Sequelae Has Been Misinterpreted as Common Aortopulmonary Trunk
4. Single Ventricle

Stay updated, free articles. Join our Telegram channel

Join