Atrioventricular Canal Type Research Articles

Diagnosis of Ductal Aneurysm Using Three-Dimensional CT Reconstruction

The prevalence of ductal aneurysms is approximately 8.8% [2]. Ductal aneurysms are associated with serious complications, which makes accurate diagnosis prudent. Diagnosis is traditionally made by echocardiography, however, additional imaging modalities are sometimes required for a definitive diagnosis. Our patient, D.C., is a full-term newborn male who was transferred from an outside hospital to our Neonatal Intensive Care Unit secondary to respiratory failure and dysmorphism. His physical examination was significant for hypertelorism and low-set ears. He had increased precordial activity and a 3/6 holosystolic murmur heard throughout the precordium. An echocardiogram was performed on day of life 5, which showed a primum atrial septal defect (ASD) with left-to-right shunt, a secundum ASD with left-to-right shunt, and atrioventricular canaltype ventricular septal defect with no physiologic shunt secondary to atrioventricular valve tissue filling the defect. At that time echocardiography demonstrated significant left pulmonary artery stenosis. A follow-up echocardiogram was performed to further evaluate the caliber of the left pulmonary artery. A 1.6 9 1.8-cm cystic mass was noted anterior to and to the left of the main pulmonary artery/left pulmonary artery junction. There appeared to be a connection via a small communication to the main pulmonary artery (Fig. 1). A CT angiogram was performed, which showed a well-circumscribed contrast-filled structure measuring 1.7 9 1.4 9 1.2 cm arising from the anterior aspect of the proximal portion of the descending thoracic aorta, located anterolateral to the left main pulmonary artery branch, most consistent with a pseudoaneurysm. However, the exact anatomy was still difficult to precisely delineate. Therefore, we used three-dimensional reconstruction of the CT angiogram to show the aneurysm in connection with the ductus arteriosus and to demonstrate compression of the left pulmonary artery by the aneurysm (Fig. 2). Ductal aneurysms are rare and are more frequently associated with patients who have had surgical ligation of the ductus arteriosus or in association with connective tissue disorders [1]. One study demonstrated a prevalence of 8.8% in all newborn infants [2]. Ductal aneurysms usually are asymptomatic and incidentally discovered on routine echocardiographic evaluation or diagnosed by fetal echocardiogram. Although rare, ductal aneurysms are associated with serious complications, which include thromboembolism, infection, rupture, and death [3]. The conventional method to identify ductal aneurysm anatomy is by two-dimensional echocardiogram with color Doppler. However, some patients require additional imaging with CT angiography or MRI to further define the anatomy [1]. In our patient, the connection between the aneurysm and the artery was difficult to isolate on two-dimensional echocardiogram and CT angiogram. Therefore, three-dimensional reconstruction of the CT angiogram was necessary to make the exact diagnosis. Additionally, the three-dimensional reconstruction replicated the exact area of aneurysmal connection to the pulmonary artery. Three-dimensional CT has been described more often in the adult literature for diagnosis of aneurysms. The most common use is as a diagnostic tool for circle of Willis aneurysms. However, three-dimensional CT angiography has been used to diagnose aortic aneurysms in the adult population. In pediatrics, three-dimensional CT angiography Deneen Heath and Russell Cross contributed equally to this work.

Complete Atrioventricular Canal Repair Under 1 Year: Rastelli One-Patch Procedure Yields Excellent Long-Term Results

Considering more recently proposed techniques, we have evaluated our midterm and long-term results of Rastelli one-patch repair in complete atrioventricular canal. Between 1984 and 2005, 107 patients with a complete atrioventricular canal underwent a Rastelli one-patch procedure. Two groups were identified: 1984 to 1995 and 1995 to 2005 (respectively, 56 and 51 patients). Mean age at surgery was 5.3 +/- 3.4 months; mean weight was 5.5 +/- 3 kg; trisomy 21 was present in 81 patients; complete atrioventricular canal type A was found in 67 patients, type C in 40 patients. There were 12 cases of potentially parachute mitral valve and 14 associated anomalies treated simultaneously (pulmonary obstruction 11, coarctation 3). The coronary sinus was always left on the right side. After functional and anatomic evaluation, the cleft was closed completely in 8 and partially in 29, and was left intact in 70 cases. Early survival was 86% +/- 3%. Five patients underwent early reoperation for residual ventricular septal defect (n = 2) and mitral valve repair (n = 3). Nine patients underwent late reoperations with successful repair: subaortic stenosis (n = 4) and mitral valve repair (n = 5). Late survival at 10 and 15 years was 84% +/- 3%. Freedom from reoperation for mitral regurgitation was 94% +/- 3% at 10 years, and 91% +/- 3% at 15 and 20 years. At last follow-up 30 patients had mild and 3 had moderate mitral regurgitation. Rastelli single-patch repair in complete atrioventricular canal is a safe and reproducible technique. Among survivors, freedom from late reoperation for mitral regurgitation is very satisfactory. A properly taught, learned, and transmitted Rastelli one-patch technique compares very well with any other proposed technique.

Cleft closure and undersizing annuloplasty improve mitral repair in atrioventricular canal defects

Reoperation rates to correct left atrioventricular valve regurgitation after primary repair of atrioventricular canal defects remain relatively high. The causes of valvular regurgitation are likely multifactorial, and simple cleft closure is often insufficient to prevent recurrence. To elucidate the mechanisms leading to regurgitation, we conducted hemodynamic studies using isolated native mitral valves. Anatomy of these valves was altered to mimic atrioventricular canal type valves and studied under pediatric hemodynamic conditions. The impact of subvalvular geometry, cleft closure, annular dilatation, and annular undersizing on regurgitation were investigated. Papillary muscle position did not have a significant effect on regurgitation. Cleft closure had a significant impact on valvular competence, with reduction in regurgitation volume with increased cleft closure. Regurgitation volume decreased from 12.5 +/- 2.4 mL/beat for an open cleft to 4.9 +/- 1.9 mL/beat for a partially closed cleft and to 1.4 +/- 1.6 mL/beat when the cleft was completely closed. Annular dilatation had a significant impact on regurgitation even after cleft closure. A 40% increase in annular size increased regurgitation by 59% for a partially closed cleft and by 84% for a fully closed cleft. Reducing the annular size by 20% from the physiologic level decreased the regurgitation volume by 12% for a fully open cleft and by 58% for the partially closed cleft case. Annular dilatation after primary repair has a potentially significant role in the recurrence of atrioventricular valve regurgitation. Reducing the annular size and restricting dilatation as an adjunct to cleft closure is a promising surgical approach in such valve anatomies.

Primary surgical repair of ventricular septal defect.

Between January 1983 and December 2000, 78 patients underwent primary repair of a ventricular septal defect. There were 42 males (54%) and 36 females (46%) of whom 13 (17%) were under 1 year old, 50 (64%) were aged 1-10 years, 11 (14%) were aged 10-20 years, and 4 (5%) were over 20 years old. The ventricular septal defect was a perimembranous type in 60 patients (77%), subarterial (outlet) type in 10 (13%), and atrioventricular canal (inlet) type in 4 (5%). Operative repair was performed with a patch in all except 2 patients. Early postoperative complications included insignificant aortic regurgitation in 4 patients, persistent complete heart block in 1, and residual shunt in 4. There were 5 early deaths (6.4%) and 1 late death (1.8%) in 56 patients followed up. Early primary closure of ventricular septal defects, usually via a right atriotomy, can be performed with acceptable mortality and morbidity rates.

Straddling tricuspid valve as a sign of ventriculoatrial malalignment: A morphometric study of 19 postmortem cases

Background Straddling tricuspid valve, despite extensive investigation, remains an incompletely understood form of complex congenital heart disease. Methods A morphometric study of 19 postmortem cases of straddling tricuspid valve was performed, and the results were compared with 32 normal control heart specimens. Results In straddling tricuspid valve, marked malalignment of the ventricles was always found relative to the atria. The angle between the ventricular septum and the atrial septum in the short-axis projection averaged 61° ± 24°, the normal ventriculoatrial septal angle averaging 5° ± 2° ( P < .001). The right ventricular sinus (inflow tract) was significantly smaller than the left ( P < .01). A ventricular septal defect was present in 79%: atrioventricular canal type in 42%, atrioventricular canal type confluent with a conoventricular defect in 26%, and a conoventricular defect in 11%. When the straddling tricuspid valve adhered to the crest of the muscular ventricular septum (n = 4 cases, 21%), the 2 salient findings were (1) an intact ventricular septum and (2) double-outlet right atrium. The nonstraddling part of the tricuspid valve opened into the small right ventricle. The straddling part of the tricuspid valve opened into the larger left ventricle. The mitral valve also opened into the left ventricle. Hence hearts with double-outlet right atrium had 3 atrioventricular valves. Congenital mitral stenosis was present in 26% of this series. Conclusion Straddling tricuspid valve was always characterized by marked ventriculoatrial malalignment, indicated by an abnormally large ventriculoatrial septal angle, best seen in the short-axis projection. (Am Heart J 1999;138:1184-95.)

Double-outlet right atrium with restrictive ostium primum and incomplete supravalvular ring presenting as congenital mitral valve stenosis

We have recently encountered a rare case of partial atrioventricular (AV) canal. The malformation included a persistent left superior vena cava draining into a dilated coronary sinus. The left and right auriculoventricular valves were abnormal, as usually seen in partial AV canal. The restrictive ostium primum and surrounding atrial septum were malaligned and displaced in a left posterior position. An incomplete supravalvular ring was found above the lateral component of the left AV valve. This anomaly, which is identified as double-outlet right atrium, was misdiagnosed before the operation and was responsibie for a clinical presentation similar to congenital mitral valve stenosis resulting from supravalvular ring. We present a case to draw attention to this rare diagnosis (double-outlet right atrium) as an unusual cause of impediment to left AV valve inflow and to include it in the differential diagnosis of mitral valve stenosis with basically normal subvalvular apparatus. The patient was a 14-year-old girl, known since childhood to have a cardiac murmur. Although she had reduced physical activity, she developed satisfactorily, without cyanosis. When she was 8 years old, a diagnosis of congenital mitral stenosis resulting from a supravalvular ring was made, and it was confirmed 2 years later by a different pediatric cardiologist. In June 1993, surgical repair was advised owing to cardiac enlargement. The New York Heart Association functional class was II. On physical examination, the patient was a thin prepubertal noncyanotic girl with mild psychomotor impairment. The sternum was of pectus excavatum type. The jugular venous pressure was within normal limits. No peripheral edema was apparent. Cardiac auscultation revealed a holosystolic grade 3/6 murmur, best heard at the apex and the axillar area. There was also a grade 2/6 diastolic murmur. The second heart sound was normal. The lungs were clear to auscultation, and the liver and spleen were not enlarged. The electrocardiogram showed normal sinus rhythm with electrical signs of right ventricular hypertrophy. The cardiothoracic ratio was 0.55, and the aspect of the left ventricle was suggestive of mitral stenosis. The preoperative echocardiogram showed a partial AV canal type

Evaluation of ventricular septal defect by transesophageal echocardiography: Intraoperative assessment

The miniaturization of transesophageal echocardiography (TEE) probes, together with the development of the capability for biplane imaging from the esophagus, have increased the use of TEE in pediatric cardiology. The aim of this study was to evaluate the TEE findings in patients with ventricular septal defect (VSD) before and after closure primarily by means of pediatric biplane probes. This study group included 69 patients who underwent VSD closure as an isolated repair or as a part of a definitive repair of a more complicated lesion. Ages ranged from 6 days to 15.6 years (median 1 year, 4 months), with operative weights ranging from 2.9 kg to 68 kg (median 10 kg). Preoperative and follow-up transthoracic echocardiograms (TTE) were also performed. Intraoperative TEE was performed without complication in all 69 patients. Preoperative results: (1) anatomic findings: Two muscular VSDs were detected by matrix TEE but could not be observed by TTE. A patient with preoperative TTE diagnosis of an ostium primum ASD was found to have atrioventricular (AV) canal by TEE. In three of six AV canal type VSDs, both TTE and TEE demonstrated left ventricular-right atrial shunting (2) aortic regurgitation associated with VSD: Aortic regurgitation as a result of right coronary cusp prolapse was detected in one of five supracristal VSDs in which the biplane or matrix TEE was used. In another two patients with perimembranous VSD, coronary cusp prolapse was detectable only by TEE, but no regurgitation was found; (3) tricuspid valve pouch/aneurysm/straddling and chordal attachment: In 19 of 30 cases with perimembranous VSD and two of 6 cases with AV canal VSDs, the presence of a TV pouch was detected by TEE. Six of these 21 pouches were not seen on the TTe examination. In a patient with AV canal VSD, TV straddling was observed only by TEE; (4) diameter measurements (comparison between TTE and TEE): A moderate correlation was found when the largest VSD diameter measured in any plane by TTE was compared to the largest diameter measured by TEE ( r = 0.76, p < 0.01) in 26 perimembranous VSDs. There was good agreement between diameter measurements obtained by TTE and TEE except with AV canal VSDs, where TEE diameter (especially transverse plane) was consistently larger than the TTE diameter, although the number of patients was too small for statistical analysis. Postoperative results: Residual leaks and additional VSDs: In 25 patients residual leaks were diagnosed by TEE (23 of these were considered to be hemodynamically insignificant). The remaining two were recognized to be clinically important and reoperated before the chest was closed. Intraoperative TEE with biplane capability is of significant value in defining anatomic features and physiologic characteristics of flow through VSDs.

Superior QRS axis in ventricular septal defect.

The relation between the superior orientation of the QRS axis and the anatomical site of the defect in the ventricular septum in patients with a ventricular septal defect was studied. Of 1031 patients with a ventricular septal defect, 64 (6.2%) had a superior axis on their electrocardiogram. In 59% of these patients the defect was in the inlet portion of the ventricular septum or affected this area. None of the cases was classified as an isolated ventricular septal defect of the persistent atrioventricular canal type. While there is an association between a superior axis and perimembranous inlet ventricular septal defect, a superior QRS axis does not characterise a ventricular septal defect as being of the atrioventricular canal type.

Partial atrioventricular canal in an adult: Mitral valve repair by reverse implantation of a Carpentier ring

A severely incompetent mitral valve of partial atrioventricular canal type was repaired by reverse implantation of a Carpentier ring. The flat segment of the ring was adapted to the lateral leaflet of the valve and the curved segment to the combined left superior and left inferior leaflets. The so-called cleft was sutured. The procedure resulted in a fully competent mitral valve that continues to be competent 2 years after the operation.

Identification and localization of ventricular septal defect by gated magnetic resonance imaging

Gated magnetic resonance imaging was performed to identify the morphologic characteristics of the ventricular septum in 17 normal volunteers and to localize a ventricular septal defect (VSD) in 22 patients using the multisectional spin-echo technique (0.35 tesla). Location of VSDs was corroborated by 2-dimensional echocardiography or angiography or both. The 4 portions of the ventricular septum could be easily identified, especially on transverse images. The VSD was visualized in 20 of the 22 patients. The smallest VSD identified was 0.3 cm in diameter. The 2 VSDs not identified were a small membranous VSD under conditions of excessive patient motion, causing poor-quality images, and a VSD in a 3-month-old infant in which a 3-mm gap existed between sections. The exact location of the VSD could be identified in the other 20 patients. The VSD was perimembranous in 10 patients, inlet in 4, complete atrioventricular canal type in 3 and outlet in 6. The outlet consisted of 1 subpulmonic and 5 malalignment defects. Transverse images were most effective for identification of VSD. Thus, magnetic resonance imaging is a useful noninvasive technique for identifying the ventricular septum and assessing VSDs. It has the potential to be an alternative to angiography in patients beyond infancy for definitive diagnosis and localization of VSD before surgery.

Anomalous mitral 'cleft' with abnormal ventriculo-arterial connection: anatomical findings and surgical implications.

Seven specimens with a 'cleft' mitral valve associated with anomalous chordal fixation and abnormal ventriculo-arterial connection are presented. Four were associated with a discordant ventriculo-arterial connection, two with double-outlet right ventricle, and one with double-outlet left ventricle. In six the chordae from the cleft were attached to the anterior border of a small ventricular septal defect. In the seventh the chordae were attached to an accessory papillary muscle in the left ventricular outflow tract. These clefts differ from those of atrioventricular defects. The cleft is more anterior, there are no septal defects of the atrioventricular canal type, and no deficiency of the basal ventricular septum. Mitral regurgitation or left ventricular outlet obstruction are possible consequences of the anomaly.

Transposition of the Great Arteries and Ventricular Septal Defect: Results with the Senning Operation and Closure of the Ventricular Septal Defect in Infants

From May, 1978, to July, 1982, 46 infants ranging in age from 12 days to 12 months and in weight from 2.1 to 8.4 kg underwent repair of dextrotransposition of the great arteries ( d-TGA) and ventricular septal defect (VSD) using a Senning repair and closure of the VSD. Ventricular septal defects were classified as membranous (47.8%), maialigned (28.3%), atrioventricular (AV) canal type (13.0%), subarterial (2.2%), muscular (2.2%), and multiple (6.5%). Hospital mortality was 15.2% and late mortality, 5.1%. Postoperative complications included tricuspid regurgitation (mild in 3 and severe, requiring tricuspid valve replacement, in 3), residual VSD (pulmonary/systemic flow ratio of greater than 2:1) in 3 patients (2, AV canal type and 1, multiple VSDs), pulmonary venous obstruction in 3 patients, and permanent complete heart block in 4 patients (2, AV canal type of VSD also requiring tricuspid valve replacement). Lung biopsy studies showed reversible Heath-Edwards and morphometric changes. No patient was seen with Heath-Edwards III or greater changes. In 10 patients, right ventricular end-diastolic pressures and pulmonary artery pressures at rest were within normal limits one year after operation. As the operative mortality of atrial inversion and arterial switch operations for d-TGA with VSD tends to become comparable, more extensive follow-up data, including cardiac catheterization and coronary arteriography in a large number of patients, will be necessary to establish the superiority of one approach over the other.

Histopathological correlation between the QRS axis and disposition of the atrioventricular conduction system in common atrioventricular orifice and in its related anomalies.

Serial sections of the atrioventricular (AV) conduction system were microscopically studied in 12 autopsied hearts: four with complete type common AV orifice (CAVO), two with atrial septal defect of the ostium primum type (ASD-I), two with ventricular septal defect of the persistent common AV canal type (VSD-C) and four without heart disease. The anatomic findings were semiquantitatively compared with the normal control using Feldt's method and correlated to the mean frontal QRS axis on ECG. The cases of CAVO or VSD-C with left axis devation invariably showed similar patterns regarding the location and course of the AV conduction system: (1) posterior displacement of the AV node, (2) relatively short distance between the AV node and the beginning of the left bundle branch (LBB), and (3) postero-inferior displacement of the bundle of His and the LBB. The postero-inferior displacement of the LBB seemed to be responsible for left axis deviation. The cases of ASD-I showed some additional findings: (1) impaired contiguity between the AV node and the bundle of His might have caused the occasional advanced AV block in one case, and (2) the posterior radiation of the LBB traversed down through the branch-free muscle bundle, which was assumed to be related to the right axis deviation in the other case. These findings suggest that the disposition of the AV conduction system in CAVO and in its related anomalies were basically the same whatever the type of defect, and this was considered to be correlated to the established ECG pattern.

Transatrial correction of origin of both great vessels from right ventricle with pulmonary hypertension

The operative treatment of seven patients with origin of both great vessels from the right ventricle plus pulmonary hypertension is discussed. Except for one patient with an atrioventricular canal type of ventricular septal defect (VSD), all patients had subaortic VSDs. All had transatrial repair, and none died. The clinical and operative findings and the merits of a transatrial approach are discussed.

Tetralogy of Fallot with type C complete atrioventricular canal Surgical repair in three cases

The successful repair of three consecutive cases of tetralogy of Fallot associated with complete atrioventricular canal type C is reported. The correct preoperative diagnosis was established by right and left ventriculography. Operative repair in the first two patients involved division of both hemivalves above the crest of the ventricular septal defect and closure of the septal defects with a single large Dacron patch. In the third patient, the septal defects were closed with two separate patches. The undivided hemivalves were attached to the patches by interrupted sutures placed more to the right side of the midline, so that tricuspid tissue was used to reconstitute the mitral valve. Right ventricular outflow tract obstruction was relieved by infundibulectomy, pulmonary valvulotomy, and placement of a Darcon patch on the infundibulum in Cases 1 and 3. A valved tube was used in Case 2. Six months postoperatively, the condition of the patient is satisfactory. The first patient is receiving digitalis; the second, digitalis and diuretics; and the third patient is well without treatment.

Straddling and displaced atrioventricular orifices and valves.

This is an anatomic study of 96 hearts with straddling or displaced atrioventricular (AV) valves and orifices. In the complete form, both the annulus and the peripheral connections of either AV valve straddle a ventricular septal defect (VSD) and connect to both ventricles. In the annular form, only the annulus, and in the peripheral type only the peripheral connections of the valve are found in both ventricles. In displaced AV valve, the entire annulus and periphery of one AV valve are displaced into the opposite chamber. These anomalies are commonly seen in complete transposition with or without ventricular inversion, and in double outlet right or left ventricle. Straddling mitral valve is frequently seen in the Taussig-Bing heart. Any type of VSD may be associated with straddling tricuspid valve; however, they usually are of the AV canal type. Straddling and displaced AV valves should be differentiated from criss-cross hearts in which both AV valves are completely connected to oppositely placed ventricles.

Overriding tricuspid valve: Echocardiographic and angiocardiographic features

Eight cases are presented in which the diagnosis of overriding of the tricuspid valve was made during life and the electrocardiographic, echocardiographic and angiographic features of this defect are presented. Four of the patients had dextrotransposition of the great arteries, three had normally related great arteries and one had corrected transposition. In each case there was hypoplasia of the right ventricle and a ventricular septal defect of the atrioventricular (A-V) canal type. The electrocardiogram in the cases with d-transposition was characterized by diminished right ventricular forces, left ventricular hypertrophy and a superior leftward frontal plane axis. The echocardiogram in seven cases demonstrated a septal leaflet of the tricuspid valve opening posterior to the septum into the left ventricle. In four cases the anterior leaflet of the tricuspid valve was shown crossing the plane of the interventricular septum as it opened in diastole. The diagnosis in five cases was made angiographically by a left ventricular injection in the left anterior oblique projection. In this view the septum was viewed tangentially and in diastole the negative silhouette of the tricuspid valve was seen straddling the interventricular septum. The presence of an overriding tricuspid valve can greatly complicate repair of intracardiac defects. The diagnosis of this A-V valve anomaly can be accurately made with the use of echocardiography and selective left ventricular angiography.

Echocardiographic diagnosis of endocardial cushion defects.

Sixteen patients with endocardial cushion defects were studied by echocardiography and ultrasonocardiotomography. Three characteristic findings, common to both complete and partial forms, were observed. They were the ostium primum defect of the interatrial septum, the left ventricular outflow narrowing and the atrioventricular valve abnormalities which are the anatomic bases of endocardial cushion defects. Several additional findings were observed in patients with complete form. Most strikingly, the anterior leaflet echo locating in the left ventricle had the direct connection to that in the right ventricle without the interposition of the interventricular septum by echocardiogram. Ultrasonocardiotomogram, on the other hand, demonstrated beautifully the common anterior leaflet and the high inteventricular septal defect. There were, in addition, the absence of the paradoxical motion of the interventricular septum and the diffuculty in detecting the interatrial septum. The intact interatrial septum continuous with the anterior mitral leaflet was demonstrated in patients with the interventricularseptal defect of atrioventricular canal type, in which there were the typical abnormalities in the atrioventricular valves and the left ventricular outflow narrowing as well. This study indicates that ultrasonic examination may provide a direct, yet noninvasive method in the diagnosis of various types of endocardial cushion defects.

Double-outlet right ventricle with pulmonic stenosis. Surgical considerations and results of operation.

The results of complete repair of double-outlet right ventricle with pulmonic stenosis in 22 Mayo Clinic patients were analyzed. The overall mortality rate was 32%. Since 1960, the mortality rate has been reduced to 16%. Anomalies of the distribution of the right coronary artery, a second ventricular septal defect of the atrioventricular canal type, and significant residual pulmonic stenosis were associated with a higher mortality rate. The difficulties in the diagnosis of this uncommon condition are emphasized. Complete repair is best carried out after the patient is 4 years old. A systemic-to-pulmonary arterial shunt is the procedure of choice for those who are younger than this. In the occasional patient with anomalous distribution of the right coronary artery which precludes adequate relief of the pulmonic stenosis, use of an aortic homograft from the right ventricle to the pulmonary artery should be considered.

Double-outlet right ventricle without pulmonic stenosis. Surgical considerations and results of operation.

The results of complete repair of double-outlet right ventricle without pulmonic stenosis in 18 Mayo Clinic patients are analyzed; the over-all operative mortality rate was 22%. Pulmonary vascular obstructive disease and a second ventricular septal defect of the atrioventricular canal type were associated with a higher mortality rate. The difficulties in the diagnosis of this uncommon condition are emphasized. Patients with double-outlet right ventricle without pulmonic stenosis should have complete repair early in life before the onset of severe pulmonary vascular obstructive disease-the only specific contraindication to operation. Pulmonary artery banding may be preferable as a first-stage palliative procedure in infants less than six months old who do not respond to medical therapy.