Atrioventricular septal defects: What's in a name?

Personalized Diagnoses for Those Born with Congenitally Malformed Hearts

Background/Objectives: It is increasingly realized that the advances in diagnosis and treatment for those born with congenitally malformed hearts have now resulted in avoidance of morbidity being equally as important as avoiding postoperative mortality. Detailed personalized diagnoses will now be key to achieve such improvements. Methods: We have reviewed our own experience in diagnosing major phenotypic variations on selected congenital cardiac malformations, showing that the ability to personalize the findings is at hand, although not always to date universally employed. Results: We have chosen four categories to illustrate how the definitions now provided by the International Nomenclature Society, and incorporated in the 11th iteration of the International Classification of Disease, make it possible to provide personalized diagnoses. The lesions chosen for review are the arrangement of the atrial appendages, the lesions permitting interatrial shunting, the options in the setting of deficient ventricular septation, and the abnormal morphology of the aortic root. We show that not all centers, as yet, are taking advances of these opportunities at hand to tailor the chosen treatments. Conclusions: Detailed phenotypic definitions have now been provided for all the major congenital cardiac malformations. Use of these definitions should now provide personalized medicine for all those born with malformed hearts. As yet, the definitions are not used to their full effect.

Role of ECG in the Accidental Finding of an Atrioventricular Septal Defect in an Asymptomatic Patient Undergoing Cosmetic Surgery

Electrocardiogram (ECG) is an important diagnostic tool in identifying congenital heart disease (CHD), as demonstrated by this case of a 48-year-old female who presented for a preoperative evaluation for cosmetic surgery. ECG showed a right bundle branch block (RBBB) and first-degree atrioventricular (AV) block, and further testing revealed a primum atrial septal defect (ASD) with mitral valve anterior leaflet cleft and a membranous ventricular septal defect (VSD). She underwent successful surgical repair and was discharged home without complications. This case highlights the importance of performing additional tests like echocardiography or other imaging modalities in cases of abnormal ECG findings to accurately diagnose the underlying heart condition and ensure proper treatment.

Reconstruction of the Left Atrioventricular Valve with Pericardial Patch Closure of the Ostium Primum Atrial Septal Defect in a Patient with Partial Atrioventricular Septal Defect under Mild Hypothermic Extracorporeal Circulation and Cardioplegic Arrest (UKC’s Modification): A Video Presentation

A 26-year-old male patient diagnosed with partial type of atrioventricular septal defect in sinus rhythm, cleft left atrioventricular valve with mild pulmonary arterial hypertension, and severe left atrioventricular valvular regurgitation successfully underwent reconstruction of the left atrioventricular valve and pericardial patch closure of the atrial septal defect using UKC’s modification. The technical details of the surgical procedure have been elaborated in detail.

Atrioventricular septal defect with an absent or tiny ostium primum defect: a case series of three surgical cases

Although atrioventricular septal defects are categorized according to the anatomical atrioventricular orifice, the location of the intracardiac shunt in atrioventricular septal defects is important from a surgical perspective. Herein, we report three cases of atrioventricular septal defects with a small or no ostium primum defect. Case 1 (3-month-old girl) was diagnosed preoperatively with a ventricular septal defect, secundum atrial septal defect, and mitral valve cleft. After the operation, the diagnosis was corrected to an atrioventricular septal defect and was repaired completely. Case 2 (9-year-old girl) underwent pulmonary artery banding for a ventricular septal defect with a straddling mitral valve. After the experience with Case 1, we realized similarities between Cases 1 and 2. Therefore, we corrected the diagnosis to atrioventricular septal defect and achieved definitive repair. Based on these experiences, we accurately diagnosed Case 3 (3-month-old boy) with an atrioventricular septal defect. This variant is poorly known; however, proper morphological understanding is necessary to facilitate anatomical repair and prevent postoperative atrioventricular blocks. Some cases of this variant may be diagnosed as a ventricular septal defect with straddling mitral valve and are unable to receive definitive repair. The direction of the cleft, absence of atrioventricular valve offsetting, and trileaflet of the left atrioventricular valve all seem useful for making a diagnosis, and these can be easily confirmed by echocardiography.

Reoperations After Repair for Atrioventricular Septal Defects: >25 Years Experience at a Single Center

Our aim was to evaluate the total burden of reoperations after previous repair for atrioventricular septal defects, including long-term survival and identify risk factors for reoperation. All patients with surgical correction for atrioventricular septal defect (AVSD) 1993- 2020 underwent a follow-up in October 2020. Clinical data were obtained by retrospective review and evaluated with Kaplan-Meier and competing risk analysis. Of 477 patients who underwent initial repair, 53 patients (11.1%) underwent a total of 82 reoperations. The perioperative mortality at reoperation was 3.8% (2/53). There were no late deaths (0/51) during follow-up. In patients requiring reoperation for left atrioventricular valve regurgitation, a re-repair was performed in 90% (26/29) at first attempt. Estimated overall survival was 96.2 ± 2.6% (95% CI 91.2-100) in the Any reoperation group and 96.7 ± 0.9% (95% CI 94.9-98.5) in the No reoperation group at 20 years (P = 0.80). The cumulative incidence function of Any reoperation (with death as competing risk) was 13.0% (95% CI 9.4-16.5) at 20 years. Independent risk factors for Any reoperation included severe mitral regurgitation after primary repair (HR 40.7; 95% CI 14.9-111; P < 0.001). The risk of perioperative mortality in AVSD patients undergoing reoperation was low in the present study. Long-term survival was very good and not significantly different when compared to patients who did not need reoperation. Re-repair for left atrioventricular valve regurgitation was possible in most cases and showed long-term durability. Our data suggest that reoperations after primary repair of AVSD have very good long-term outcomes when performed at a high-volume pediatric cardiac surgery center.

Atrioventricular Septal Defect: What Is in a Name?

Robert Anderson has made a huge contribution to almost all aspects of morphology and understanding of congenital cardiac malformations, none more so than the group of anomalies that many of those in the practice of paediatric cardiology and adult congenital heart disease now call 'Atrioventricular Septal Defect' (AVSD). In 1982, with Anton Becker working in Amsterdam, their hallmark 'What's in a name?' editorial was published in the Journal of Thoracic and Cardiovascular Surgery. At that time most described the group of lesions as 'atrioventricular canal malformation' or 'endocardial cushion defect'. Perhaps more significantly, the so-called ostium primum defect was thought to represent a partial variant. It was also universally thought, at that time, that the left atrioventricular valve was no more than a mitral valve with a cleft in the aortic leaflet. In addition to this, lesions such as isolated cleft of the mitral valve, large ventricular septal defects opening to the inlet of the right and hearts with straddling or overriding tricuspid valve were variations of the atrioventricular canal malformation. Anderson and Becker emphasised the differences between the atrioventricular junction in the normal heart and those with a common junction for which they recommended the generic name, 'atrioventricular septal defect'. As I will discuss, over many years, they continued to work with clinical cardiologists and cardiac surgeons to refine diagnostic criteria and transform the classification and understanding of this complex group of anomalies. Their emphasis was always on accurate diagnosis and communication, which is conveyed in this review.

Insights from examination of hearts from adults dying suddenly to the understanding of congenital cardiac malformations

Congenital heart disease is a rare but important finding in adults who experience sudden death. Examination of the congenitally malformed heart has historically been considered esoteric and best left to those with expertise. The Cardiac Risk in the Young cardiovascular pathology laboratory based at St George's University of London has now received over 6,000 cases. Of these, 21 congenitally malformed hearts were retained for research and educational purposes. Hearts were assessed using sequential segmental analysis, and causes of death were adjudicated based on thorough macroscopic examination and histology. Congenital malformations that were encountered included atrial septal defects, ventricular septal defects, tetralogy of Fallot, and transposition of the great arteries in both its regular and congenitally corrected variants. Findings also included hearts with mirror-imaged and isomeric atrial appendages. Direct causes of death included myocardial fibrosis, pulmonary hypertension, and hemorrhage. A small but notable proportion did not reveal a substrate for arrhythmia, raising the question of whether the terminal event was due to the congenital heart disease itself, or an underlying channelopathy. Here, we demonstrate the value of simple sequential segmental analysis in describing and categorizing the cases, with the concept of the "morphological method" serving to identify the distinguishing features of the cardiac components. Clin. Anat. 33:394-404, 2020. © 2019 Wiley Periodicals, Inc.

Revisiting Anatomy of the Interatrial Septum and its Adjoining Atrioventricular Junction Using Noninvasive Imaging Techniques

Interest in the anatomy of the interatrial septum (IAS) and its adjoining atrioventricular (AV) junction has risen enormously in the past two decades with the simultaneous evolution of left-sided percutaneous structural heart disease and complex electrophysiologic procedures. These procedures require, in fact, a direct route to the left atrium through the IAS. Thus, a thorough understanding of the complex anatomy of the IAS and AV junction is essential for performing a safe and effective transseptal puncture. There is a large amount of literature carefully describing the anatomy of the IAS and AV junction. These studies are based almost exclusively on anatomic specimens. Conversely, in this review the authors emphasize the role of noninvasive imaging techniques, in particular cardiac magnetic resonance, two- and three-dimensional transesophageal echocardiography, and computed tomography in visualizing specific aspects of the normal IAS and AV junction. Where appropriate, the authors present images side by side, with corresponding anatomic specimens.

What is the real cardiac anatomy?

The heart is a remarkably complex organ. Teaching its details to medical students and clinical trainees can be very difficult. Despite the complexity, accurate recognition of these details is a pre‐requisite for the subsequent understanding of clinical cardiologists and cardiac surgeons. A recent publication promoted the benefits of virtual reconstructions in facilitating the initial understanding achieved by medical students. If such teaching is to achieve its greatest value, the datasets used to provide the virtual images should themselves be anatomically accurate. They should also take note of a basic rule of human anatomy, namely that components of all organs should be described as they are normally situated within the body. It is almost universal at present for textbooks of anatomy to illustrate the heart as if removed from the body and positioned on its apex, the so‐called Valentine situation. In the years prior to the emergence of interventional techniques to treat cardiac diseases, this approach was of limited significance. Nowadays, therapeutic interventions are commonplace worldwide. Advances in three‐dimensional imaging technology, furthermore, now mean that the separate components of the heart can readily be segmented, and then shown in attitudinally appropriate fashion. In this review, we demonstrate how such virtual dissection of computed tomographic datasets in attitudinally appropriate fashion reveals the true details of cardiac anatomy. The virtual approach to teaching the arrangement of the cardiac components has much to commend it. If it is to be used, nonetheless, the anatomical details on which the reconstructions are based must be accurate. Clin. Anat. 32:288–309, 2019. © 2019 The Authors. Clinical Anatomy published by Wiley Periodicals, Inc. on behalf of American Association of Clinical Anatomists.

Surgery for partial atrioventricular septal defect with pulmonary hypertension in an adult dog

A 4-year-old, 5.9-kg female Japanese Spitz presented with syncope and exercise intolerance. Echocardiography revealed an ostium primum atrial septal defect (ASD), a cleft mitral valve, mitral valve regurgitation (MR), and tricuspid regurgitation (TR) (velocity: 3.6 m/sec, pressure gradient: 52 mmHg), leading to a diagnosis of partial atrioventricular septal defect (AVSD) with moderate pulmonary hypertension (PH). Open-heart surgery using cardiopulmonary bypass was performed through right atriotomy. The cleft of the mitral valve was sutured with polypropylene and the AVSD was closed using an autologous pericardial patch fixed with glutaraldehyde. No postoperative pulmonary hypertensive crisis occurred. Shunting flow through the ASD, TR and PH had completely disappeared 2 months postoperatively; however, moderate MR persisted. The dog is still alive 5 years postoperatively without clinical signs.

Surgical Repair of Complete Atrioventricular Septal Defect

Between January 1988 and March 1996, 40 patients underwent repair of complete atrioventricular septal defect with a two-patch technique and routine atrioventricular valve cleft closure. The mean age of the patients was 10.8 ± 6.9 months and the mean weight was 6.6 ± 2.6 kg. Twenty-three had Down's syndrome and 13 had coexisting cardiac anomalies. Preoperative angiography and echocardiography revealed mild atrioventricular valve regurgitation in 22 patients, moderate regurgitation in 16, and severe regurgitation in the other 2. The mortality was 12.5% (4 early and 1 late deaths). The major cause of death was pulmonary hypertensive crisis. Reoperation was necessary in 3 patients; 2 had atrioventricular valve annuloplasty and one had prosthetic valve replacement. All 3 survived reoperation. Echocardiography at a mean of 32 ± 20 months postoperatively showed mild left atrioventricular valve regurgitation in 32 patients and moderate regurgitation in 3. Management of postoperative pulmonary hypertensive crisis and repair of complete atrioventricular septal defect before the development of high pulmonary vascular resistance may reduce the mortality of this surgical procedure.

Clarifying the morphology of the ostium primum defect

The 'ostium primum' defect is still frequently considered to be the consequence of deficient atrial septation, although the key feature is a common atrioventricular junction. The bridging leaflets of the common atrioventricular valve, which are joined to each other, are depressed distal to the atrioventricular junction, and fused to the crest of the muscular ventricular septum, which is bowed in the concave direction towards the ventricular apex. As a result, shunting across the defect occurs between the atrial chambers. These observations suggest that the basic deficiency in the 'ostium primum' defect is best understood as a product of defective atrioventricular septation, rather than an atrial septal defect. We have now encountered four examples of 'ostium primum' defects in mouse embryos that support this view. These were identified from a large number of mouse embryo hearts collected from a normal, outbred mouse colony and analysed by episcopic microscopy as part of an ongoing study of normal mouse cardiac development. The abnormal hearts were identified from embryos collected at embryonic days 15.5, 16.5 and 18.5 (two cases). We have analysed the features of the abnormal hearts, and compared the findings with those obtained in the large number of normally developed embryos. Our data show that the key feature of normal atrioventricular septation is the ventral growth through the right pulmonary ridge of a protrusion from the dorsal pharyngeal mesenchyme, confirming previous findings. This protrusion, known as the vestibular spine, or the dorsal mesenchymal protrusion, reinforces the closure of the primary atrial foramen, and muscularises along with the mesenchymal cap of the primary atrial septum to form the ventro-caudal buttress of the oval foramen, identified by some as the 'canal septum'. Detailed analysis of the four abnormal hearts suggests that in each case there has been failure of growth of the vestibular spine, with the result that the common atrioventricular junction found earlier during normal development now persists during cardiac development. Failure of separation of the common junction also accounts for the trifoliate arrangement of the left atrioventricular valve in the abnormal hearts. Analysis of the episcopic datasets also permits recognition of the location of the atrioventricular conduction axis. Comparison of the location of this tract in the normal and abnormal hearts shows that there is no separate formation of a ventricular component of the 'canal septum' as part of normal development. We conclude that it is abnormal formation of the primary atrial septum that is the cause of so-called 'secundum' atrial septal defects, whereas it is the failure to produce a second contribution to atrial septation (via growth of the vestibular spine) that results in the 'ostium primum' defect.

The development of septation in the four-chambered heart

The past decades have seen immense progress in the understanding of cardiac development. Appreciation of precise details of cardiac anatomy, however, has yet to be fully translated into the more general understanding of the changing structure of the developing heart, particularly with regard to formation of the septal structures. In this review, using images obtained with episcopic microscopy together with scanning electron microscopy, we show that the newly acquired information concerning the anatomic changes occurring during separation of the cardiac chambers in the mouse is able to provide a basis for understanding the morphogenesis of septal defects in the human heart. It is now established that as part of the changes seen when the heart tube changes from a short linear structure to the looped arrangement presaging formation of the ventricles, new material is added at both its venous and arterial poles. The details of these early changes, however, are beyond the scope of our current review. It is during E10.5 in the mouse that the first anatomic features of septation are seen, with formation of the primary atrial septum. This muscular structure grows toward the cushions formed within the atrioventricular canal, carrying on its leading edge a mesenchymal cap. Its cranial attachment breaks down to form the secondary foramen by the time the mesenchymal cap has used with the atrioventricular endocardial cushions, the latter fusion obliterating the primary foramen. Then the cap, along with a mesenchymal protrusion that grows from the mediastinal mesenchyme, muscularizes to form the base of the definitive atrial septum, the primary septum itself forming the floor of the oval foramen. The cranial margin of the foramen is a fold between the attachments of the pulmonary veins to the left atrium and the roof of the right atrium. The apical muscular ventricular septum develops concomitant with the ballooning of the apical components from the inlet and outlet of the ventricular loop. Its apical part is initially trabeculated. The membranous part of the septum is derived from the rightward margins of the atrioventricular cushions, with the muscularizing proximal outflow cushions fusing with the muscular septum and becoming the subpulmonary infundibulum as the aorta is committed to the left ventricle. Perturbations of these processes explain well the phenotypic variants of deficient atrial and ventricular septation.

Anatomy of common atrioventricular junction with complex associated lesions

The essence of the lesion increasingly described as atrioventricular septal defect is the presence of a common atrioventricular junction. In most instances, the common junction is itself shared in more or less equal fashion between the cardiac chambers, producing the so-called balanced arrangement, which can be considered the default option. Complexity can be produced at various levels within this standard lesion. The most complex malformations are seen in the setting of visceral heterotaxy. Greatest complexity is seen with right isomerism. This always includes totally anomalous pulmonary venous connection, even when the pulmonary veins return to the heart. Still further complexity is often added by the presence of pulmonary stenosis or atresia. Imbalance can involve either the atrial or ventricular chambers. Imbalance at atrial level produces one form of double outlet atrium, but typically with balanced ventricles. Ventricular imbalance represents spectrums extending either to double inlet left or right ventricle through a common atrioventricular valve. Complexity at the level of the ventriculoarterial junctions is seen in the form of abnormal ventriculoarterial connections, notably tetralogy of Fallot or double outlet right ventricle. In these settings, the superior bridging leaflet is free-floating. Hypoplasia of the left atrioventricular valve is part of right ventricular dominance and is often associated with the so-called parachute malformation. Dual orifice is also a problem. In both these lesions, the zone of apposition between the bridging leaflets is the effective inlet to the left ventricle.

Morphology and Morphogenesis of Atrioventricular Septal Defect With Common Atrioventricular Junction

For many years, the lesions now often described as atrioventricular septal defects were considered to represent atrioventricular canal malformations or endocardial cushion defects. It was also long recognized that patients with the so-called ostium primum defect should be included in this category. The phenotypic feature of these hearts is the presence of a common atrioventricular junction, as opposed to separate right and left atrioventricular junctions. The presence of the common atrioventricular junction underscores the associated phenotypic features, such as the presence of a trifoliate left atrioventricular valve, which has no resemblance to a cleft mitral valve; unwedging of the subaortic outflow tract; and disproportion between the inlet and outlet dimensions of the left ventricle. These features are comparable in patients having the so-called partial, intermediate, and complete variants of the malformation. Anatomical differentiation depends on the morphology of the leaflets of the common atrioventricular valve that bridge the ventricular septum. If these bridging leaflets are fused one to the other, then there are dual orifices, rather than a common orifice, within the common atrioventricular junction. The relationships of the bridging leaflets to the septal structures determine the potential for shunting across the atrioventricular septal defect, which can occur at atrial and ventricular levels or exclusively at either atrial or ventricular level. Rarely, the atrioventricular septal defect may close spontaneously. Recent evidence from studies of cardiac development shows that rather than being an endocardial cushion defect, the malformation results from failure of ingrowth into the developing heart from the dorsal mesenchymal tissues.

Surgical Anatomy of Atrioventricular Septal Defect

This review aims to describe the anatomic spectrum of hearts classified with the collective term atrioventricular septal defect. Despite their anatomical variety, hearts with the stigmata of atrioventricular septal defect share the characteristic feature of a common atrioventricular junction guarded by a 5-leaflet valve. The lack of normal atrioventricular septation makes the aorta un-wedged, resulting in an elongated outlet length on the left ventricular surface (known as inlet-outlet disproportion). The major determinant of anatomic variations is the relationship of the bridging leaflets to the septal structures. This important relationship determines not only the level of intracardiac shunting (interatrial only, interventricular only, or both) but also the propensity for left ventricular outflow tract obstruction. Furthermore, the location of the atrioventricular node, which is posteroinferiorly displaced from the tip of the triangle of Koch, is also affected by this relationship. Understanding the cardiac anatomy in this malformation is an absolute prerequisite for successful surgery, and should be facilitated by recognizing the fundamental nature of the morphology.

Understanding atrioventricular septal defect: anatomoechocardiographic correlation

OBJECTIVE

Correlate the anatomic features of atrioventricular septal defect with echocardiographic images.

MATERIALS AND METHODS

Sixty specimen hearts were studied by sequential segmental analysis. Echocardiograms were performed on 34 patients. Specimen hearts with findings equivalent to those of echocardiographic images were selected in order to establish an anatomo-echocardiographic correlation.

RESULTS

Thirty-three specimen hearts were in situs solitus, 19 showed dextroisomerism, 6 were in situs inversus and 2 levoisomerism. Fifty-eight had a common atrioventricular valve and 2 had two atrioventricular valves. Rastelli types were determined in 21 hearts. Nine were type A, 2 intermediate between A and B, 1 mixed between A and B, 4 type B and 5 type C. Associated anomalies included pulmonary stenosis, pulmonary atresia atrial septal defect, patent ductus arteriosus and anomalous connection of pulmonary veins. Echocardiograms revealed dextroisomerism in 12 patients, situs solitus in 11, levoisomerism in 7 and situs inversus in 4. Thirty-one patients had common atrioventricular valves and three two atrioventricular valves. Rastelli types were established in all cases with common atrioventricular valves; 17 had type A canal defects, 10 type B, 3 intermediate between A and B, 1 mixed between A and B and 3 type C. Associated anomalies included regurgitation of the atrioventricular valve, pulmonary stenosis, anomalous connection of pulmonary veins, pulmonary hypertension and pulmonary atresia.

CONCLUSION

Anatomo-echocardiographic correlation demonstrated a high degree of diagnostic precision with echocardiography.

Surgical correction of a partial atrioventricular septal defect with a ventricular septal defect in a dog

Echocardiography of a dog with a cardiac murmur revealed an ostium primum septal defect, a ventricular septal defect, and mitral valve malformation with regurgitation. The mitral valve and tricuspid valve were separated and displaced at the same level as the ventricular septum. The mitral valve had a cleft in the septal cusp. Cardiac catheterization and angiocardiography showed a left-to-right shunt and a "goose-neck sign," which indicated an elongated left ventricular outflow tract. The diagnosis of a partial atrioventricular septal defect with ventricular septal defect was made. Surgical correction was successfully performed under extracorpo-real circulation using a cardiopulmonary bypass system.

Overview: history, anatomy, timing, and results of complete atrioventricular canal

The past 50 years have been marked by major advances in the care of children with complete atrioventricular canal defects. There have been important contributions from surgeons, cardiologists, and pathologists to provide us with our current understanding of the anatomy of atrioventricular canal defects and excellent surgical outcomes. In this monograph we will discuss the surgical contributions of Lillehei, Kirklin, McGoon, Maloney, Trusler, Wilcox, and Nunn. The improvements in outcomes achieved by these surgeons were made possible by the pathology and anatomy clarifications provided by Lev, Rastelli, and Anderson.

Early Repair of Complete Atrioventricular Septal Defect is Safe and Effective

BACKGROUND

Surgical repair of complete atrioventricular septal defect (CAVSD) is a well-established procedure performed on young children. Our hypothesis is that with modern techniques, the current risks of CAVSD repair in children aged younger than 3 months and in children older than 3 months are equal.

METHODS

This was a retrospective review of 65 infants and children with a mean age of 10.9 months (range, 1 month to 15.5 years) who underwent CAVSD repair from 1990 to 2004. Twenty-six repairs (40%) were done on or before 3 months of age (group A) and 39 repairs (60%) were done after 3 months of age (group B). In all patients, the ventricular septal defect was repaired with an individualized approach according to each patient's specific anatomy: direct suturing without a patch, interposition of a small pericardial patch with a running suture, or both. The atrioventricular commissure was closed with interrupted sutures, and all atrial defects were closed with a pericardial patch. Data were analyzed using the chi2 analysis and the Fisher exact test.

RESULTS

Three hospital deaths occurred (<30 days), 2 in group A and 1 in group B (7.7% vs 2.6%, respectively, p = 0.33). One death in group A occurred during another noncardiac surgery. Early reoperation (<1 year of initial surgery) for residual ventricular septal defect or significant mitral regurgitation, or both, occurred in 3 group A patients and in 4 group B patients (11.5% versus 10.3% respectively, p = 0.68).

CONCLUSIONS

These results suggest that repair of CAVSD defects in children 3 months of age or younger had similar outcomes compared with those who underwent surgical repair after 3 months of age.

Echo-morphological correlates in patients with atrioventricular septal defect and common atrioventricular junction

It is now well recognized that patients fulfilling the diagnostic criterions for the group of hearts usually described as atrioventricular canal malformations, or atrioventricular septal defects, can present with shunting at atrial level, at both atrial and ventricular levels, and on occasion, with shunting only at ventricular level.1,2It is also well recognized that, in most instances, the patients with shunting exclusively at atrial level have separate atrioventricular valvar orifices for the right and left ventricles, this arrangement often described as the “ostium primum” variant of atrial septal defect.3Morphological and echocardiographic studies, however, have shown that, in this variant presumed to represent deficient atrial septation, it is the atrioventricular septal structures, rather than the atrial septum, which are deficient, the phenotypic feature being the presence of a common atrioventricular junction.4,5In this review, we will show how, using modern day echocardiographic techniques, particularly the newly developed potential for three-dimensional display, it is an easy matter to identify the presence or absence of the common atrioventricular junction, and then to demonstrate the various relationships between the valvar leaflets, the septal structures, and the common junction itself which determine the options for clinical presentation within the group.

Surgical validation of real-time transthoracic 3D echocardiographic assessment of atrioventricular septal defects

BACKGROUND

The purpose of this study was to evaluate the accuracy of AV valve morphology assessed by real-time transthoracic 3D echocardiography (RT-3DE) compared to surgical findings and to assess whether RT-3DE is applicable in clinical practice.

METHODS

Between June 2004 to May 2005, 19 patients with an atrioventricular septal defect (AVSD) undergoing surgical treatment at our institution were enrolled in the study. RT-3DE was performed with Philips Sonos 7500 echo-system and off-line analysis with TomTec Echoview software. The AVSD was assessed for the morphology of AV valve, with particular interest to the superior and inferior bridging leaflets. 3D data were compared with measurements and descriptions acquired during the surgical procedure.

RESULTS

Acquisition of RT-3DE datasets was feasible in all patients. Of the 19 patients, there were 11 infants (age <1 year). The duration of 3D data acquisition was 12+/-3 min for patients above 1 year and 4+/-2 for infants. Reconstruction time was 22+/-8 min. In all patients the AV valve orifice and RT-3DE observations of the superior and inferior bridging leaflets were all correctly identified by RT-3DE compared with the surgical findings.

CONCLUSION

Real-time transthoracic 3D echocardiography provides accurate assessment of AVSDs and correctly depicts the AV valve morphology. After a short learning curve, RT-3DE is easily applicable during daily clinical practice.

Complete versus partial atrioventricular canal: equal risks of repair in the modern era

OBJECTIVE

To assess the authors' hypothesis that with modern techniques, the current risks of repair for both complete and partial atrioventricular canal (AVC) are equal.

SUMMARY BACKGROUND DATA

Repair of complete AVC in infancy has traditionally carried a substantial mortality. In contrast, partial AVC has been considered low-risk for repair and can be performed later in childhood.

METHODS

This was a retrospective review of 63 infants and children who underwent complete (n = 40) or partial AVC repair (n = 23) from 1990 to 2001. Among complete AVC patients, the ventriculoseptal defect was repaired via an individualized approach according to each patient's specific anatomy: direct suturing without a patch (n = 5) and/or interposition of a small pericardial patch with a running suture (n = 35). In all 63 patients the left AV valve cleft was closed with interrupted sutures, and all atrial defects were closed with a pericardial patch. Data were analyzed with the Student test and Fisher exact test.

RESULTS

Results are expressed as the mean +/- SEM. Age at operation was 6.3 +/- 2.0 months for complete AVC and 47.5 +/- 6.1 months for partial AVC (P <.001). Bypass time was 65.2 +/- 2.3 minutes for complete AVC and 58.3 +/- 3.9 minutes for partial AVC ( P=.1). Reoperation rate was 7.5% (3/40) for complete AVC and 13.0% (3/23) for partial AVC ( P=.6). Early mortality was 2.5% (1/40) for complete AVC and 0% (0/23) for partial AVC ( P=.6).

CONCLUSIONS

Compared to partial AVC, patients presenting for complete AVC repair are significantly younger and manifest more complex anatomy and pathophysiology. However, utilizing modern techniques, including an individualized surgical approach to the ventricular component, repair of complete AVC yields reoperation and early mortality rates similar to those of partial AVC.

Surgical repair of complete atrioventricular septal defect

BACKGROUND

The objective of this study was to assess the outcome of complete atrioventricular septal defect repair from 1981 to 2000.

METHODS

One hundred seventy-two consecutive patients with atrioventricular septal defect were operated on by a single surgeon using a consistent operative technique (single patch; "cleft" closure). The patients' age range was from 5 weeks to 9 years (mean, 10.8 +/- 1.2 months).

RESULTS

Overall operative mortality was 15 of 172 (8.7%) and this decreased significantly from 12 of 73 (16.4%) in the first decade to 3 of 99 (3.0%) in the second decade (p = 0.0021) with no operative deaths in the last 51 patients. Operative mortality was related to decade of operation (p = 0.0021) and to use of crystalloid cardioplegia (p = 0.0047) by univariate analysis, and to decade of operation (p = 0.0016) and postoperative time on ventilator (p = 0.0023) by multivariate analysis. Actuarial long-term survival including operative deaths was 79.0% +/- 3.8% at 15 years. Ten of 157 (6.4%) operative survivors have undergone reoperation for late mitral regurgitation (9 mitral valve repair, 1 mitral valve replacement) with one death. Four of 8 patients surviving late mitral valve replacement have subsequently required mitral valve repair. Freedom from late reoperation for severe mitral regurgitation was 89.9% +/- 3.1% at 15 years. Freedom from late reoperation for mitral regurgitation did not decrease in the second decade (84.2% +/- 6.6% at 10 years) versus the first decade (94.5% +/- 3.1%) (p = 0.0679).

CONCLUSIONS

Although operative mortality for repair of atrioventricular septal defect has decreased dramatically during the past decade, the incidence of late reoperation for mitral regurgitation has not improved, and better techniques to eliminate late mitral regurgitation are needed.

Atrioventricular septal defects: possible etiologic differences between complete and partial defects

BACKGROUND

Recent advances in clinical, pathological, and genetic aspects of atrioventricular septal defects (AVSD) have set the stage for epidemiologic investigations into possible risk factors. Previous analyses of the total case group of AVSD included complete and partial subtypes without analysis of the subsets.

METHODS

To address the question of possible morphogenetic heterogeneity of AVSD, the Baltimore-Washington Infant Study data on live-born cases and controls (1981-1989) was reanalyzed for potential environmental and genetic risk-factor associations in complete AVSD (n = 213), with separate comparisons to the atrial (n = 75) and the ventricular (n = 32) forms of partial AVSD.

RESULTS

Complete and ventricular forms of AVSD had a similar proportion of isolated cases (12.2% and 15.6%, respectively, without associated extracardiac anomalies) and high rates of Down syndrome, whereas the atrial form of partial AVSD included 55% isolated cases. Trisomy 18 occurred in 22% of infants with the ventricular form, compared with <2% in the other AVSD groups. Analysis of potential risk factors revealed further distinctions. Complete AVSD as an isolated cardiac defect was strongly associated with maternal diabetes (odds ratio [OR] = 20.6; 95% confidence interval [CI] =5.6-76.4) and also with antitussive use (OR = 8.8; CI = 1.2-48.2); there were no strong associations other than maternal age among Down syndrome infants with this type of heart defect. Isolated cases with the atrial type of partial AVSD were associated with a family history of heart defects (OR = 6.2; CI = 1.4-24.4) and with paternal occupational exposures to ionizing radiation (OR = 5.1; CI = 1.4-27.4), but no risk factors were associated with Down syndrome. There were no significant associations of any risk factors in the numerically small subsets of isolated and Down syndrome cases with the ventricular form of partial AVSD.

CONCLUSIONS

These results indicate a similar risk profile of complete AVSD and the ventricular type of partial AVSD, with a possible subset of the latter due to trisomy 18. Maternal diabetes constituted a potentially preventable risk factor for the most severe, complete form of AVSD.

Anatomy of the human atrioventricular junctions revisited

There have been suggestions made recently that our understanding of the atrioventricular junctions of the heart is less than adequate, with claims for several new findings concerning the arrangement of the ordinary working myocardium and the specialised pathways for atrioventricular conduction. In reality, these claims are grossly exaggerated. The structure and architecture of the pathways for conduction between the atrial and ventricular myocardium are exactly as described by Tawara nearly 100 years ago. The recent claims stem from a failure to assess histological findings in the light of criterions established by Monckeberg and Aschoff following a similar controversy in 1910. The atrioventricular junctions are the areas where the atrial myocardium inserts into, and is separated from, the base of the ventricular mass, apart from at the site of penetration of the specialised axis for atrioventricular conduction. There are two such junctions in the normal heart, surrounding the orifices of the mitral and tricuspid valves. The true septal area between the junctions is of very limited extent, being formed by the membranous septum. Posterior and inferior to this septal area, the atrial myocardium overlies the crest of the ventricular septum, with the atrial component being demarcated by the landmarks of the triangle of Koch. The adjacent structures, and in particular the so-called inferior pyramidal space, were accurately described by McAlpine (Heart and Coronary Arteries, 1975). Thus, again there is no need for revision of our understanding. The key to unravelling much of the alleged controversy is the recognition that, as indicated by Tawara, the atrioventricular node becomes the atrioventricular bundle at the point where the overall axis for conduction penetrates into the central fibrous body. There are also marked differences in arrangement, also described by Tawara, between the disposition of the conduction axis in man as compared to the dog.

Congenital Heart Surgery Nomenclature and Database Project: atrioventricular canal defect

The extant nomenclature for atrioventricular (AV) canal/atrioventricular septal defect is reviewed for the purpose of establishing a unified reporting system. The subject was debated and reviewed by members of the STS-Congenital Heart Surgery Database Committee and representatives from the European Association for Cardiothoracic Surgery. All efforts were made to include all relevant nomenclature categories using synonyms where appropriate. The three general categories are: partial AV canal (ostium primum defect), transitional (intermediate) AV canal, and complete AV canal. A comprehensive database set is presented that is based on a hierarchical scheme. Data are entered at various levels of complexity and detail that can be determined by the clinician. These data can lay the foundation for comprehensive risk stratification analyses. A minimum database set is also presented that will allow for data sharing and would lend itself to basic interpretation of trends. Outcome tables relating diagnoses, procedures, and various risk factors are presented.

Three-dimensional echocardiographic analysis of valve anatomy as a determinant of mitral regurgitation after surgery for atrioventricular septal defects

Mitral regurgitation (MR) is a significant complication after atrioventricular septal defect (AVSD) surgery. The relation of the valve leaflet morphology and the MR mechanism remains a conundrum. Two-dimensional echocardiography depicts leaflet edges, whereas volume-rendered 3-dimensional echocardiography provides direct visualization of the surface areas of the mitral valve leaflets. This study examines the relation of mitral valve anatomy as determined by 3-dimensional echocardiography with MR origins in patients after AVSD repair. Twenty-seven patients with AVSD surgery and Doppler color MR were prospectively enrolled (median age was 5 years and 16 patients had Down syndrome). Doppler color flow imaging of the MR jet and 3-dimensional echocardiography of the mitral valve were performed with a probe in the transthoracic or transesophageal position. Enface 3-dimensional views of the mitral valve from the left atrium were reconstructed. Analysis of the 3-dimensional data was possible in 21 of the 27 patients. Mean area ratios of the 3 mitral leaflets were calculated (superior 40 +/- 7%, inferior 35 +/- 5%, mural 25 +/- 6%). Both intra and interobserver variability on the area measurements were <5%. In 12 patients (group 1) the jet appeared to emanate medially from the region of coaptation of the superior and inferior components of the anterior leaflet. In 9 patients (group 2) the jet emanated more laterally from the region toward the mural leaflet. The area ratios of the inferior leaflet were 32 +/- 4% in group 1 and 38 +/- 6% in group 2 (p = 0.02). The area ratios of the mural leaflet were 28 +/- 5% in group 1 and 21 +/- 5% in group 2 (p = 0.007). The superior leaflet area ratio was not different in groups 1 and 2, 40 +/- 9% and 41 +/- 6%, respectively. Three-dimensional echocardiography provides new insight into the anatomic determinants of MR following AVSD surgery.

An unusual tethering of the bridging leaflets in atrioventricular septal defect producing a communication from left atrium to right ventricle

We describe a 39-year-old woman who was diagnosed as having an unusual atrioventricular septal defect with a communication from left atrium to right ventricle. A common atrioventricular junction, with partially separated right and left atrioventricular orifices, was found at transoesophageal ultrasonic examination. Both bridging leaflets were attached to the underside of the atrial septum, which was grossly malaligned relative to the ventricular septum. The shunt was exclusively from left atrium to right ventricle because of the overriding of the left atrioventricular valve, with the left component of the inferior bridging leaflet firmly fused to the ventricular septal crest.

Predisposing factors of valve regurgitation in complete atrioventricular septal defect

OBJECTIVES

We sought to determine the intrinsic risk factors of valve regurgitation in complete atrioventricular septal defect.

BACKGROUND

Progression of regurgitation varies in each case, although the structure of the common atrioventricular valve itself is a predisposing factor.

METHODS

In 90 consecutive patients undergoing surgical repair, we evaluated the preoperative and postoperative regurgitation, valve morphology, age at surgery and associated anomalies. A regurgitation jet with a high velocity reaching the deep left atrial wall by echocardiography was estimated as marked regurgitation.

RESULTS

None of the 40 patients with Rastelli type C and an undivided inferior bridging leaflet had preoperative regurgitation in the first year of life, and 12% of them (95% confidence intervals [CI]: 0% to 28%) showed regurgitation at the age of 2. Of the remaining 50 with Rastelli type A and/or a divided inferior leaflet, regurgitation was determined in 21% (95% CI: 6% to 35%) of those 1 year old and in 49% (95% CI: 29%7 to 69%) of those 2 years old (p < 0.01). All patients underwent corrective surgery using the double-patch technique, with the "cleft" being sutured adequately. Irrespective of the valve morphology, regurgitation remained in 52% (12 of 23) of those with preoperative regurgitation, whereas regurgitation developed postoperatively in 28% (16 of 58) of those without regurgitation (p < 0.001).

CONCLUSIONS

Those with Rastelli type C and an undivided inferior leaflet had a lesser degree of progression of preoperative regurgitation. However, regurgitation was likely to exist even after adequate repair once regurgitation had already advanced. Therefore, early primary repair before progression of the regurgitation may be the key to maintaining better competence of the atrioventricular valve.

The left ventricular outflow tract in atrioventricular septal defect revisited: surgical considerations regarding preservation of aortic valve integrity in the perspective of anatomic observations

OBJECTIVE

The anatomy of the left ventricular outflow tract in hearts with atrioventricular septal defect has been widely investigated, but controversies remain regarding detailed aspects of left ventricular outflow tract anatomy in the perspective of operative techniques to either prevent or relieve outflow tract obstruction.

METHODS

We investigated 29 postmortem hearts with an atrioventricular septal defect. Measurements were taken of the circumferences and of the widths of the components that make up the outflow tract, that is, the interventricular septum, the superior bridging leaflet, the left ventricular free wall, and the length of the tendinous cords.

RESULTS

The circumference of the left ventricular outflow tract immediately underneath the aortic valve was not different from that at the middle part of the outflow tract. Hearts with the partial type defect, characterized by separate atrioventricular orifices, had a smaller outflow tract than those with the complete variety. Although the anatomic constituents that contribute to left ventricular outflow tract obstruction are complex, this study showed that a reduced width of the interventricular septum was most intimately related to narrowing immediately underneath the aortic valve. Obstruction at the middle part of the left ventricular outflow tract was largely caused by reduced width of the interventricular septum together with short tendinous cords.

CONCLUSIONS

On the basis of these observations, we recommend detailed investigation of the anatomy of the left ventricular outflow tract immediately underneath the aortic valve, before surgical attempts to relieve outflow tract obstruction, because in some procedures the integrity of the aortic valve will be at stake.

Anatomically sound, simplified approach to repair of "complete" atrioventricular septal defect

BACKGROUND

There are few congenital anomalies of the heart that have benefited more from thorough anatomic analysis than the complex anomaly known as atrioventricular septal defect in the setting of common atrioventricular junction. Recent advances in understanding the anatomy of this lesion have led to alternative methods of repairing these defects.

METHODS

The medical records of 21 consecutive patients undergoing repair of complete atrioventricular septal defect have been reviewed. Nine of these patients had a standard one- or two-patch repair, and 12 had direct closure of the ventricular element of the defect.

RESULTS

Direct closure resulted in significantly shorter pump and cross-clamp times. Follow-up for an average of 34 months suggests that when direct closure can be performed, the results are comparable with those of the more standard technique.

CONCLUSIONS

Our initial success with this approach is encouraging; however, longer follow-up is required to establish whether it will be broadly applicable.