Atrioventricular septal defects: What's in a name?

Postinfarction atrioventricular septal rupture

Postinfarction communication between a left ventricular aneurysm and the right atrium is a rare acquired disease. We report a case of a 72-year-old man who recently had dyspnea on minimal exertion and was found to have left ventricle-to-right atrial shunt by two-dimensional transthoracic echocardiography. This diagnosis was confirmed with transesophageal echocardiography, cardiac catheterization, and angiography. The patient underwent successful repair but died of multisystem failure. This case shows the importance of transthoracic echocardiography for the adequate diagnosis and management of such cases.

Echocardiographic Evaluation of Common Atrioventricular Canal Defects: A Study of 206 Consecutive Patients

An accurate echocardiographic evaluation of common atrioventricular canal (CAVC) requires in-depth knowledge of the wide spectrum of morphological and physiological variations in this group of anomalies. In order to evaluate the incidence and morphological distribution of AV canal defects in a large series of patients and to define a systematic approach to the echocardiographic examination, we reviewed the echocardiograms of 206 consecutive patients with CAVC studied at Texas Children's Hospital over a 32-month period. The complete form of CAVC was most common (68.4%) and presented at an earlier age (mean +/- SD: 1.6 +/- 2.4 months). A partial AV canal (ostium primum atrial septal defect [ASD]) was found in 42 patients (20.4%) and their age at presentation was higher (9.2 +/- 10 months). Twenty-three patients (11.2%) had a transitional AV canal. Down syndrome was diagnosed in 34% of patients, the majority of whom (79%) had a complete CAVC. Associated malformations were found in 46% of patients: anomalies of the conotruncus were most frequent (18%), followed by secundum ASD (14.1%), anomalous pulmonary venous connection (11.2%), and heterotaxy syndrome (11.2%). Subaortic obstruction and mitral stenosis were less common. The AV canal was unbalanced in 14.1% of patients, with the right ventricular dominant form being more common than the left ventricular dominant form (10.7% and 3.4%, respectively). Based on our experience, we developed a systematic, segment-by-segment approach to the echocardiographic examination in infants with CAVC. Together with detailed anatomical information, Doppler evaluation provides crucial hemodynamic information that allows planning of surgical repair. (ECHOCARDIOGRAPHY, Volume 13, July 1996)

Ten-year experience with surgical treatment of partial atrioventricular septal defect: risk factors in the early postoperative period

Partial atrioventricular septal defects are electively repaired with good results. However, recent reports suggest that such repair is potentially a high-risk surgical procedure. Our aim was to determine the risk factors of adverse outcome early after surgical treatment of atrioventricular septal defects in our hospital. A retrospective study was done in 100 consecutive patients from 2 months to 50.6 years old (median 3.6 years) who underwent surgical correction between January 1984 and December 1993. An intermediate form of the lesion was noted in 31% of cases. Congestive heart failure occurred in 50% of cases. Preoperative left atrioventricular valve incompetence (moderate to severe) was present in 63% of patients. Severe abnormalities of left subvalvular apparatus were noted in 28% of patients. The cleft of the left atrioventricular valve was closed in 76% of cases. The study was done to determine risk factors associated with hospital mortality (13%), postoperative residual left atrioventricular valve incompetence (23%), and early reoperation (14%) within the first 30 postoperative days. Univariate analysis showed that age at the date of operation and cleft closure were not related to an early adverse outcome. A stepwise logistic regression with variables selected by univariate analysis identified infections and severe abnormalities of left subvalvular apparatus as predictive factors of early death (odds ratio, 28.07 and 6.18, respectively), preoperative left atrioventricular valve regurgitation as a predictive factor of residual postoperative left atrioventricular valve regurgitation (odds ratio, 5.34), and severe abnormalities of left subvalvular apparatus as a predictive factor of early reoperation (odds ratio, 5.27). These results emphasize the importance of the severity of the morphologic features of the left subvalvular apparatus, the occurrence of early postoperative infections, and the presence of residual left atrioventricular valve regurgitation as risk factors in the early period after surgical correction of partial atrioventricular septal defects.

Is a cleft in the anterior leaflet of an otherwise normal mitral valve an atrioventricular canal malformation?

OBJECTIVES

This study sought to ascertain the surgical anatomy of a cleft in the left atrioventricular (AV) valve.

BACKGROUND

Important morphologic differences exist between hearts with a cleft in the anterior leaflet of an otherwise normal mitral valve and those with a so-called cleft in the left AV valve when there is an AV septal defect, but it has been customary to link the lesions together on developmental grounds.

METHODS

Eight autopsied specimens with a cleft in the aortic (or anterior) leaflet of the mitral valve were studied in detail, and echocardiograms from 21 patients with such a cleft were compared with the specimens and with findings typical of the so-called partial AV canal and other forms of AV septal defect.

RESULTS

The structure and direction of the cleft, location of the papillary muscles within the left ventricle and AV junctional morphology of hearts with an otherwise normally structured mitral valve were significantly different from typical findings in hearts with AV septal defects.

CONCLUSIONS

It is necessary to distinguish morphologically a cleft in an otherwise normally structured mitral valve in hearts with separate right and left AV junctions from the trifoliate left component of a common AV valve in hearts with an AV septal defect and a common AV junction because the disposition of the AV conduction tissues varies markedly between the lesions.

Clinical anatomy of the atrioventricular junctions

OBJECTIVES

This study reevaluated the anatomy of the areas anterior and posterior to the atrioventricular (AV) septal structures, previously said to represent anterior and posterior septal areas.

BACKGROUND

In descriptions of the locations of accessory AV pathways within the AV junctions, four regions have been recognized: the left and right free walls and the anterior and posterior septums. On the basis of known facts concerning cardiac structure, it is questionable whether these so-called septums are truly septal.

METHODS

Ten human hearts were dissected to elucidate the clinical anatomy of these purportedly septal regions, together with the overall arrangement of the AV junctions.

RESULTS

The true septal components of the AV junctions are the muscular and membranous AV septal areas. These separate the cavity of the right atrium from that of the left ventricle. The region previously designated as the anterior septum is part of the right parietal junction. It is contiguous with the membranous part of the septum but extends anteriorly and laterally from the septum as part of the supraventricular crest of the right ventricle ("crista supraventricularis"). In the region posterior to and beneath the mouth of the coronary sinus, only the most anterior extent, in continuity with the central fibrous body, is part of the muscular AV septum. The posterior extent of this area roofs over the diverging right and left ventricular walls and is filled in with fibroareolar tissue of the AV groove.

CONCLUSIONS

The larger part of the regions anterior and posterior to the true AV septal areas are not septal but are parts of the parietal AV junctions. An understanding of these anatomic relations is essential for those wishing to modify conduction across the AV junctions.

Valve morphology in complete atrioventricular septal defect: variability relevant to operation

The remodeling of the atrioventricular valves in patients with complete atrioventricular septal defects is the crucial part of surgical repair. Variability in valve morphology is an important factor. This study evaluates the variability in morphology of the anterior and posterior leaflets in 30 heart specimens. All hearts had an anterior bridging leaflet: Rastelli type A in 12, type B in 2, and type C in 16. The posterior leaflet revealed four morphologic patterns: a right- and left-sided posterior leaflet, both inserting directly onto the crest of the ventricular septum (5 hearts); a common posterior leaflet attached to the septal crest by a membrane (2 hearts); a common posterior leaflet attached to the septal crest by multiple chordae (13 hearts); and a virtually free-floating posterior leaflet (11 hearts). The categorization is surgically relevant in making a distinction between hearts with and without an interventricular communication underneath the posterior leaflet. Surgically relevant variations occurred also in arrangement and positioning of chordae originating from the right septal side. There was no relationship between the Rastelli classification of the anterior leaflet and that of the posterior leaflet. The variability in morphology of the posterior leaflet and its attachments to the ventricular septum appear equally crucial for successful repair as that of the anterior leaflet.

Morphology of the posterior junctional area in atrioventricular septal defects

The location and size of the coronary sinus in hearts with atrioventricular septal defect were investigated in relation to the known disposition of the atrioventricular conduction axis. We examined the morphology in 40 hearts and supplemented this series with two other hearts that had been serially sectioned previously. The coronary sinus received drainage from a persistent left superior caval vein in 5 hearts. Six cases of 40 had malalignment of the septal structures relative to the crux of the heart. In these, the conduction axis was anticipated to course in the position where the inlet ventricular septum met the atrioventricular junction. The coronary sinus terminated in the left atrium in 4 hearts: 2 in the morphological series and 2 that were sectioned for histological studies. The sectioned hearts showed the atrioventricular conduction axis in the usual position for the defect, unrelated to the coronary sinus. The principle that the node and penetrating bundle are located at the intersection of the ventricular septum with the atrioventricular junction holds good despite the variability of the coronary sinus.

Endocardial cushion defect: further studies of "isolated" versus "syndromic" occurrence

The isolated occurrence of endocardial cushion defect (ECD) has been suggested to differ from its occurrence within the context of a syndrome, with regard to the nature (complete or partial) of the defect and the associated cardiovascular malformations. Analysis of data derived from the Baltimore-Washington Infant Study of congenital cardiovascular malformations supports the observation that "syndromic" ECD tends to be of the complete atrioventricular canal type and is less frequently associated with left cardiac anomalies than the isolated form. However, each syndrome has a unique impact on the overall cardiovascular "phenotype", including the ECD. This is especially true for Down and Ivemark syndromes, which are most frequently associated with ECD, but also for other syndromes as well. It is also suggested that isolated ECD is specifically associated with gastrointestinal and urinary tract anomalies. However, in Down syndrome ECD appears to be a specific cardiovascular expression of the trisomic state that is unrelated to other noncardiac malformations. Additional information on the association of ECD with other less common genetic syndromes is needed in order to further investigate the possible genetic basis of this cardiac defect.

The surgical anatomy of ventricular septal defect

There is still no consensus as to how best to categorize and describe interventricular communications. In a series of three reviews, a system will be described showing how the anatomical criteria chosen for categorization will also serve as a guide for surgeons as to the location of the axis responsible for atrioventricular conduction tissue. In this first review, the defects described are not complicated by overriding of arterial or atrioventricular valves and are present in hearts that have basically normal segmental connections, or have some discordant connections (complete transposition or congenitally corrected transposition). The rims of the defect categorize the boundaries to which a surgeon may place a patch. Variations in these rims produce three classes of defect: perimembranous; muscular; and doubly committed and juxtaarterial (subarterial). The second part of the classification recognizes the further variation existing with respect to the component of the morphologically right ventricle into which the defect predominantly empties. Deficient atrioventricular septation can also lead to interventricular shunting in isolation, but the morphology is then quite different from hearts with simple deficiencies of the ventricular septum. We emphasize the abnormal location of the atrioventricular node in hearts with atrioventricular, as opposed to ventricular, septal defects.

Echocardiographic evaluation of atrioventricular orifice anatomy in children with atrioventricular septal defect

In atrioventricular (AV) septal defect, the common AV valve can have a common orifice or can be divided by bridging leaflet tissue into two separate orifices. To determine the accuracy of a two-dimensional echocardiographic technique devised specifically for evaluation of the number of AV valve orifices, all 69 children undergoing surgical repair of AV septal defect from April 1987 to August 1990 were examined prospectively. The presence of bridging leaflet tissue and the number of AV valve orifices were determined with use of a subcostal imaging plane. From a standard subcostal four-chamber view, the plane of sound was rotated 30 degrees to 45 degrees clockwise until the AV valve was seen en face. The plane of sound was then tilted from a superior to an inferior direction so that cross-sectional views of the AV valve were examined from the inferior margin of the atrial septum to the superior margin of the ventricular septum. Of the 69 patients, 6 (9%) were excluded because the appropriate subcostal images were not obtained (in 3 because of obesity and in 3 as a result of operator failure). The remaining 63 children, ranging in age from 1 day to 13.5 years and in weight from 1 to 55 kg, constituted the study group. Echocardiographic results were compared with surgical observations in 62 patients and with autopsy findings in 1 patient. With the two-dimensional echocardiographic technique, 32 of 33 patients with a common orifice and 28 of 30 patients with two separate AV valve orifices were correctly identified.(ABSTRACT TRUNCATED AT 250 WORDS)

Spectrum of heart malformations in mice with situs solitus, situs inversus, and associated visceral heterotaxy

BACKGROUND

We present a study of the heart malformations found in a collection of mouse fetuses of the iv/iv strain between days 16.5 and 18.5 of gestation.

METHODS AND RESULTS

One hundred hearts were serially sectioned and studied by segmental analysis with a light microscope. Forty additional hearts were analyzed with a scanning microscope. Forty percent of the hearts were found to be malformed. The most frequently occurring heart malformations were persistence of the sinus venosus (9%), common atrium (17%), common atrioventricular canal (24%), double-outlet right ventricle (12%), Fallot's tetralogy (8%), and transposition of the great arteries (5%). These malformations do not usually occur in isolation but rather appear in the formation of complex cardiopathies. The most severe and frequent is the combination of persistence of sinus venosus, common atrium, common atrioventricular canal, and double-outlet right ventricle; this is the "bulboventricular heart." The morphology of each lesion, as well as the degree of association, is similar to that found in human hearts with complex cardiopathies. Some of these cardiopathies appear to be directly related to formation of the cardiac loop. The iv/iv mouse appears to constitute an excellent model with which to study the etiology and pathogenesis of complex heart defects in humans. These hearts show a high phenotypic variability in the presentation of heart lesions. From a genetic viewpoint, there is a basic defect--the bulboventricular heart--which can be considered congenital. The other malformations can be considered formes frustes of the defect type.

CONCLUSIONS

The iv gene is a developmental gene that affects basic developmental mechanisms. In this regard, heart lesions may not be the primary result of the abnormal gene activity but rather are secondary to defective interactions during cardiac development.

Diagnostic echocardiographic features of the sinus venosus defect

To establish the diagnostic criteria for a sinus venosus atrial septal defect cross sectional echocardiograms, cineangiograms, and surgical notes of all patients with this diagnosis seen at the Children's Hospital of Pittsburgh between 1986 and 1988 were reviewed. Seven patients were identified. In each the extent of the atrial septum and the nature of the junction of the superior vena cava with the atria were evaluated echocardiographically from the subcostal position. All had overriding of the superior vena cava and abnormally connected right pulmonary veins. Six patients had undergone cardiac catheterisation and cineangiography. Five patients underwent surgical repair. The operative findings were consistent with the expected morphology in all five, and these features were additionally confirmed in a specimen from the cardiopathological museum. Therefore, the basic anatomical feature of a superior sinus venosus interatrial communication is a biatrial connection of the superior vena cava. This, together with anomalous drainage of the right sided pulmonary veins, results in an interatrial communication outside the confines of the true atrial septum. Overriding of the superior vena cava across the upper rim of the oval fossa is suggested as the pathognomonic diagnostic feature that can clearly be demonstrated echocardiographically from the subcostal position. In essence the lesion is an interatrial communication rather than an atrial septal defect.

Cross-sectional echocardiography in the diagnosis of atrioventricular septal defect

Between 1983-1988 cross-sectional echocardiography was performed in 63 patients having an atrioventricular septal defect with common atrioventricular orifice. We excluded from this study all those patients with separate right and left orifices ("ostium primum" defects), those with isomerism of the right and left atrial appendages, those with univentricular atrioventricular connexions and those with discordant atrioventricular and ventriculo-arterial connexions. Parasternal long- and short-axis views, apical 4-chamber views and subcostal long-axis views were employed in all patients. In the last 26 cases, we also obtained the subcostal short-axis view. Nineteen patients showed ventricular dominance, with the right ventricle being dominant in 15. Ten patients had an associated defect in the oval fossa, while the atrial septum was partially or completely absent in the other 53. A ventricular septal defect was observed in all, but it was small in 10 and multiple in 2. Attachments of the superior and inferior bridging leaflets to the crest or the right side of the ventricular septum were seen in 32 cases. The inferior leaflet was hypoplastic in 19 patients. There was narrowing of the left ventricular outflow tract in 8 patients, and obstruction of the right ventricular outflow tract in 3. Abnormal attachment of the right portion of the common valvar orifice was present in 2 cases. A solitary papillary muscle supporting the left ventricular component of the common valve was seen in 6 cases producing a parachute-like arrangement. Our study shows that cross-sectional echocardiography is an excellent technique for the analysis of this anomaly.

Late left atrioventricular valve insufficiency after repair of partial atrioventricular septal defects: anatomical and surgical determinants

Risk factors for late left atrioventricular (AV) valve insufficiency, which occurred in 16 (18%) of 90 patients evaluated after repair of partial AV septal defect, were examined. The operative findings in 9 patients undergoing reoperation were also examined. Preoperative left AV valve insufficiency was significantly more common in the group with late left AV valve incompetence, as were associated valvular malformations as a whole and fenestrations of valve leaflets in particular. Conversely, the higher incidence of malformed or malpositioned papillary muscles, accessory clefts, and double-orifice left AV valves in the group with late left AV valve insufficiency did not reach significance. The method of surgical treatment of the septal commissure was not a significant factor. In the group having reoperation, additional valvular malformations were found in association with inappropriate treatment of the septal commissure in 7 patients. The 2 remaining patients had either a directly sutured ostium primum or dilatation of the annulus. Three re-repairs were successful. Five patients required prosthetic valve replacement. Preoperative left AV valve insufficiency and associated valvular malformations are major determinants of late left AV valve insufficiency in partial AV septal defect.

A communication from the left ventricle to the right atrium: a defect in the central fibrous body

An isolated defect in the membranous atrioventricular septum was found in a five-year-old girl who presented with a cystic lesion in the right atrium. This type of left ventricular-right atrial communication could result from a structural abnormality of the central fibrous body in combination with arrested maturation of the membranous ventricular septum.

Thoughts on concepts of development of the heart in relation to the morphology of congenital malformations

In the past, it has often been the case that congenital malformations have been categorized in terms of their presumed embryologic development. The knowledge of development, however, has itself often been derived from studies of the normal heart during its development coupled with inferences drawn from the morphology of the abnormal hearts. This can lead to circular thinking which, often, has little basis in fact. It is our belief that cardiac embryology is an important science which should stand in its own right, but that knowledge of abnormal development should be derived from observation rather than inference. The potential dangers of concepts derived by extrapolation are illustrated with reference to hearts having deficiencies of atrioventricular septation ('endocardial cushion defects') and those with double inlet left ventricle ('single ventricle'). It is shown that description of these hearts is greatly facilitated by eschewing those concepts derived from 'armchair embryology'. Once a clear description is established, the scene is set to understand the real mechanisms underscoring the maldevelopment of these lesions.

Doppler mapping of postoperative left atrioventricular valve regurgitation

Left atrioventricular valve regurgitation often occurs as a postoperative hemodynamic complication from repair of an atrioventricular septal defect. In this study, cross-sectional two-dimensional Doppler flow mapping of the left atrium was used to quantify postoperative regurgitant flow in 29 patients. Its severity and location was related to the shape of the three leaflets of the left component of the atrioventricular valve, especially to the size of the mural leaflet. To identify which leaflet configuration was likely to cause regurgitation, the position of the leaflets was obtained from the parasternal short-axis view and the angular size of the mural leaflet expressed in degrees of an arc. Doppler mapping was performed in the apical four-chamber and the parasternal long-axis views, dividing the left atrium in nine squares in each. Regurgitation was defined as a jetlike systolic downstroke of the Doppler frequency shift in early systole. The angular size of the mural leaflet varied from 38 to 144 degrees (mean 86 +/- 36 SD). Massive regurgitation (six to nine sites) was encountered in seven patients, five with a mural leaflet size of over 110 degrees, one with mural leaflet size between 70 and 110 degrees, and one with a mural leaflet size of under 70 degrees. No or minimal regurgitation was encountered in 10 patients, three having a mural leaflet size of 70 to 110 degrees and seven with a mural leaflet size of less than 70 degrees. These data suggest that massive regurgitation is encountered in patients with large mural leaflets, whereas patients with smaller mural leaflets tend to have no or mild regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Developmental aspects of atrioventricular septal defects

Three human embryos with an atrioventricular septal defect were studied. Their morphology was compared with that of 67 autopsy specimens, in which particular attention was paid to the septal attachments of the bridging leaflets. The malformed embryos showed deficiency of the inlet component of the ventricular septum. They had distinct superior and inferior bridging leaflets, which were nearly completely muscular. Myocardial undermining had taken place at two independent sites but had not been able to lead to the formation of a valve of mitral morphology. Normal delamination of myocardium to form the leaflets could not continue directly below the aortic root because the rim of the inlet septum had a more apical position. From this, we conclude that the deficiency of the inlet septum is the cause of the typical morphology of the left valve in these hearts. The role of endocardial cushion tissue is probably restricted to glueing together myocardial structures, thus determining the variable septal attachment of the bridging leaflets in atrioventricular septal defect.

Complete atrioventricular canal. Anatomic study and presentation of a new technique for total correction

A new surgical technique for total correction of complete common atrioventricular canal was evolved from study of 34 specimens from affected infants who had died in the first year of life. An interventricular patch was fashioned to reconstruct the interventricular septum and the atrioventricular valves. The patch had two distinct components, one superior or atrial and the other inferior or ventricular. The division was made by inserting a lateral support at different levels on either face of the patch, to which the anterior and posterior atrioventricular cusps were sutured. The interatrial defect was closed with a patch that, together with the atrial component of the interventricular patch, produced a foramen ovale type closure mechanism. The authors present the pathologic observations which served as a basis for development of the surgical technique.

Cardiac septation in atrioventricular canal defect

To determine the relative contributions of the atrial and ventricular septa to total cardiac septation in patients with atrioventricular (AV) canal defect, two-dimensional echocardiography was used to measure the length of each portion of the septum in 14 patients with partial AV canal and 13 patients with the complete form of this lesion. Results were compared with similar data from 30 normal children, 10 patients with dilated cardiomyopathy and 11 patients with ostium secundum atrial septal defect. In patients with partial AV canal, the portion of total cardiac length occupied by the atrial septum did not differ from normal (24.8 +/- 9.9% versus 28.7 +/- 7.9%, p greater than 0.05), but there was a deficiency of both AV and ventricular septal tissue, the latter occupying only 48.2 +/- 7.0% of total cardiac length (versus 57.9 +/- 4.1% in normal subjects, p less than 0.05). Similarly, patients with complete AV canal had a normal amount of atrial septal tissue, a deficiency of AV septal tissue and a deficiency of ventricular septal tissue which was even greater than that of patients with a partial defect (39.4 +/- 5.0% versus 48.2 +/- 7.0%, p less than 0.05). Thus, although partial AV canal defect is often called ostium primum atrial septal defect, the amount of atrial tissue is usually normal, the defect being formed by a deficiency of AV and ventricular septal tissue. In the complete form of the lesion, the deficiency of ventricular septal tissue is greater.

Atrioventricular septal defects: cross-sectional echocardiographic and morphologic comparisons

We examined the cross-sectional echocardiographic findings of 171 patients with atrioventricular septal defects. The echocardiographic findings were confirmed by angiography, surgery and/or autopsy. The echocardiographic findings determined whether the common atrioventricular junction was guarded by a common valve or separate right and left valves. In addition, we were able to judge whether the bridging leaflets were related to the septal structures so as to permit both interatrial and interventricular communications [127 cases] or whether the interatrial communication ("ostium primum atrial septal defect") [43 cases] or an interventricular communication [1 case] existed in isolation. Defects existing with a common atrioventricular valve could be further classified as having minimal bridging of the antero-superior leaflet (Rastelli Type A [113 cases]); intermediate bridging (Rastelli Type B [3 cases]); or extreme bridging (Rastelli Type C [11 cases]). Of the patients with Down's syndrome, 9 had separate right and left valves while 66 had a common valve, all the latter existing in the setting of minimal bridging of the antero-superior leaflet. In the overall group, there were 9 cases having an unbalanced ventricular mass, 5 with right ventricular dominance and 4 with left dominance. Other associated defects were common. The echocardiographic findings were supplemented by pulsed Doppler examination. Atrioventricular valve insufficiency, when mild, was frequently demonstrated only in the right atrium just above the leaflets of the atrioventricular valve. When there was more severe valve insufficiency the regurgitant jet could be detected for greater distances behind the atrioventricular valve and in either or both atria, but more frequently in the left atrium. As might be anticipated in view of the complexity of the lesion, a combined imaging approach yielded the most accurate results.

The surgical anatomy of the left ventricular outflow tract in atrioventricular septal defect

The left ventricular (LV) outflow tract (OT) in atrioventricular (AV) septal defect is an important structure that paradoxically is hardly ever seen by a surgeon. The LVOT is prone to develop obstruction following surgical procedures, such as left AV valve replacement, that seemingly do not affect the LVOT itself. We examined 15 hearts with AV septal defects and noted the anatomical boundaries of the LVOT. Additionally, the LVOT was examined microscopically, and it was sectioned to replicate echocardiographic images. A sham operation was performed to show the extent of the proposed resection for AV valve replacement. The mean length of this area was 91.8 +/- 35.5% (range, 28.6 to 167.0%) of the diameter of the ascending aorta in our specimens of the Rastelli A variety. The mean diameter of the LVOT was 68.2 +/- 13.5% (range, 42.9 to 100.0%) of the diameter of the ascending aorta. The posterior wall of the OT can either be resected or widened. Resection seems to be opportune at AV valve replacement, whereas widening could be performed when the OT is intrinsically stenotic. When one fully appreciates the concept of a five-leaflet common valve, it is clear that the length of the OT depends on the extent of adherence between the superior bridging leaflet and the septal crest. In hearts that have two separate AV valve orifices, the OT is fully developed; there is no potential for interventricular shunting ("ostium primum defect"), because the superior bridging leaflet is always tightly adherent to the septal crest. AV valve replacement in these cases is especially hazardous.(ABSTRACT TRUNCATED AT 250 WORDS)

Ostium primum atrioventricular septal defect: an anatomical and surgical review

The results of surgical repair of ostium primum atrioventricular septal defect show continued improvement. This improvement reflects the advances in open-heart surgery in general and, in particular, the better understanding of the anatomy of the conduction tissue and the morphology and function of the left atrioventricular valve. We have corrected this defect in 84 patients over a ten-year period. There were 2 early deaths (2.4%) and 2 late deaths (2.4%). Two patients had problems related to conduction. Our surgical approach has been to place the interatrial baffle in such a way as to avoid the displaced atrioventricular node and thereby leave the coronary sinus in the left atrium. Our approach to repair of the so-called cleft in the left atrioventricular valve (in reality the space between the ventricular components of the bridging leaflets), is based on the unequivocal triple-leaflet morphology of this valve.

Results of total correction in complete atrioventricular septal defects with congenital or surgically induced right ventricular outflow tract obstruction

The outcome of total repair in 29 children who had complete atrioventricular septal defect (AVSD) and congenital or surgically induced right ventricular outflow tract obstruction (RVOTO) is reviewed. All 11 patients with congenital RVOTO had normal pulmonary artery (PA) pressure before the complete repair. Of the 18 children who had undergone PA banding, seven had PA pressure above 30 mm Hg (mean, 53.5). Two had elevated pulmonary vascular resistance (greater than 3 units). Early mortality was 18.2% for the patients with congenital RVOTO and 44.4% for those who had undergone PA banding (p not significant). After a mean follow-up of 5 years, the results are good in the survivors of both groups. Analysis of multiple-risk factors indicate that, for the total group of patients, death was significantly more common in children less than 5 years of age (p less than 0.01) or less than 15 kg (p less than 0.02) than in older or larger patients.

Left atrioventricular valve after surgical repair in atrioventricular septal defect with separate valve orifices ("ostium primum atrial septal defect"): an echo-Doppler study

Left atrioventricular (AV) valve dysfunction is the most frequent major postoperative hemodynamic complication in patients with AV septal defect. The anatomy and function of the left AV valve were investigated in 64 patients with separate valve orifices (ostium primum atrial septal defect) who had survived corrective surgery. M-mode and cross-sectional echocardiograms of the left AV valve were obtained. Doppler flow tracings were obtained at the left AV valve orifice to determine if regurgitation was present. The findings were related to the position of the commissures between the leaflets, the size of the 3 leaflets and the position of the papillary muscles. Left AV valve regurgitation was present in 29 of 51 patients (57%). These patients had a significantly different left AV valve leaflet configuration, characterized by a large mural leaflet and a small inferior bridging leaflet. The size of the superior bridging leaflet is not a determinant factor. Thus, the configuration of the left AV valve in AV septal defect is related to the postoperative functional result. Awareness of the echocardiographic anatomy may influence the surgical approach to this defect.

Anatomic and functional "obstruction" of the outflow tract in atrioventricular septal defects with separate valve orifices ("ostium primum atrial septal defect"): an echocardiographic study

Left ventricular (LV) outflow tract (OT) obstruction can be treacherous in any form of atrioventricular (AV) septal defect. The properties of the LVOT were investigated echocardiographically in 64 patients with separate valve orifices ("ostium primum atrial septal defect") who had survived corrective surgery. M-mode and cross-sectional echocardiographic (echo) images were made of the LVOT. The degree of malalignment of the aorta with the ventricular septum, the left atrium-aortic ratio, the fractional LV shortening and the diameter of the LVOT were recorded. Fixed anatomical obstruction was found in 3 patients, consisting of muscular bands or abnormal attachment of tension apparatus. Malalignment of the aorta with the ventricular septum was found in 62% of the patients. The diameter of the LVOT was smaller than that of the aortic root in 71% of the cases. The mean diameter of the LVOT was 92 +/- 27% (range 35 to 143%) of the aortic root diameter. Because its walls are mainly muscular, the LVOT constricts during systole. The mean end-systolic diameter of the LVOT was 77 +/- 22% (range 23 to 129%) of the aortic root diameter. Sequential measurements showed that the LVOT constricted gradually, but the velocity of constriction in patients with the most severe narrowing showed a distinct maximum in the first fifth of systole. In conclusion, a series of elements contribute to a potentially perilous arrangement of the LVOT in patients with AV septal defect. This intrinsically narrow tunnel was constricted during systole by its muscular walls.(ABSTRACT TRUNCATED AT 250 WORDS)

Results with the two-patch technique for repair of complete atrioventricular septal defect

From May, 1982, to September, 1983, 9 patients underwent repair of complete AV septal defect. They ranged in age from 11 months to 48 months and in weight from 5.3 kg to 16.5 kg. Seven patients were 24 months old or less. Previous operations included pulmonary artery banding in 1 patient and ligation of a patent ductus arteriosus with repair of coarctation in another. All patients had large left-to-right shunts (mean pulmonary to systemic flow ratio, 3.1), and the 7 young infants had marked pulmonary hypertension. Mitral regurgitation was absent in 2 patients, mild in 3, moderate in 2, and severe in 2. One patient had the right ventricular dominant form of complete AV septal defect. In all instances, repair was done using separate ventricular and atrial patches. Leaflet tissue was not divided, and a trileaflet mitral valve was left in each patient. Eight patients survived operation and are well 3 to 17 months after repair. The single operative death occurred in the patient with right ventricular dominance. Only 1 patient has mild residual heart failure 4 months after operation. Clinically, mitral regurgitation is absent in 4 patients and, at most, mild in the other 4. No patient has a conduction disturbance. Repair of complete AV septal defect is facilitated by using separate patches for the ventricular and atrial components of the defect. Less distortion is created, and a more accurate reconstruction of a competent trileaflet mitral valve can be done.

Coarctation of the aorta or subaortic stenosis with atrioventricular septal defect

Thirty patients are reported with atrioventricular (AV) septal defect and either coarctation of the aorta (C of A) or subaortic stenosis (SAS) or both. All patients had normal left ventricles as assessed by angiography (21 of 30 patients) or necropsy (9 of 30). Three groups were recognized. Groups I and II included 19 patients with AV septal defect (12 complete, 7 partial) and C of A with or without SAS, 11 patients with AV septal defect (5 complete, 6 partial) and SAS. In Group I, preductal C of A was diagnosed in 16 of 19 patients. Concomitant angiographic evidence of SAS was present in 2 cases, the mechanism being exaggerated anterior displacement of the left AV valve. In Group III, at the time of diagnosis left ventricular-aortic peak systolic pressure gradients of greater than 20 mm Hg were present in 9 patients, 2 of whom had gradients greater than 50 mm Hg. Angiographic diagnoses were: discrete fibrous diaphragm in 4, fibromuscular obstruction in 5, dynamic tunnel in 1, and chordae from left AV valve to LV outflow tract in 1. Thus, SAS in AV septal defect is most often due to a discrete anatomic lesion. Hemodynamic data show that SAS can be progressive, both before and after the surgical management of the AV septal defect.

Atrioventricular septal defect with intact atrial and ventricular septal structures

A heart with an atrioventricular septal defect is characterized by absence of the atrioventricular muscular and membranous septa, a common atrioventricular junction, an unwedged position of the aortic valve annulus and disproportionate inlet--outlet dimensions of the ventricular septum. The clinical and post-mortem findings are described of a case which had intact atrial and ventricular septa but had all the other anatomical hallmarks of atrioventricular septal defect. The problems in clinical diagnosis may be overcome by cross-sectional echocardiography.

Masked subaortic stenosis in ostium primum atrial septal defect: recognition and treatment

Five patients with ostium primum atrial septal defect (ASD) and a cleft mitral valve had no hemodynamic evidence of left ventricular (LV) outflow tract obstruction on preoperative cardiac catheterization. After surgical closure of the ASD and repair of the mitral cleft, all 5 patients manifested subaortic stenosis with pressure gradients ranging from 10 to 120 mm Hg. Postoperative LV angiograms revealed systolic narrowing of the outflow tract, and the same outflow tract dynamics were recognized on reviewing the preoperative angiograms and echocardiograms. Persistence or exaggeration of the characteristic diastolic "goose-neck" deformity during LV systole in atrioventricular canal defects is diagnostic of a potential or actual subaortic obstruction. This diagnostic sign is also readily recognizable by 2-dimensional echocardiography, and when present, the surgeon should be alerted to explore the LV outflow tract because the outflow tract anatomy is not readily apparent at operation aimed solely at closing the ASD and repairing the cleft mitral valve.