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

Correlation of ventricular septal defect height and outcomes after complete atrioventricular septal defect repair

 

OBJECTIVES

There are limited data available on the height of the ventricular component of the septal deficiency (VSD) in patients undergoing complete atrioventricular septal defect (CAVSD) repair. VSD height may influence optimal choice of repair strategy with potential consequences for long-term outcomes. We aimed to measure VSD height using 2-dimensional echocardiography and review its association with postoperative outcomes.

METHODS

We retrospectively reviewed the preoperative echocardiograms of 45 consecutive patients who underwent CAVSD repair between May 2010 and December 2015 at a single centre. VSD height and left ventricular length on the four-chamber view were measured. Demographic details and early and late outcomes including reoperation and long-term survival were studied.

RESULTS

Twenty patients underwent modified single-patch repair and 25 patients underwent double-patch repair of CAVSD. VSD height in the modified single-patch group ranged from 4.2 to 11.7 mm and in the double-patch group ranged from 5.1 to 14.9 mm. Nine patients had a deep ‘scoop’ with a VSD height of >10 mm, (7 double patch, 2 modified single patch). VSD height did not correlate with a specific Rastelli classification. There was no significant difference in the VSD height (P = 0.51) or the VSD height-to-left ventricular length ratio (P = 0.43) between the 2 repair groups. There was no 30-day mortality. Eight patients required reoperation; however, VSD height was not a significant predictor of reoperation (hazard ratio 0.95, 95% confidence interval 0.69–1.33; P = 0.08).

CONCLUSIONS

There was no correlation between VSD height and risk of reoperation after CAVSD repair. A deep ventricular scoop is uncommon in CAVSD patients.

The role of abnormal subaortic morphometry as a substrate for left ventricular outflow tract obstruction following atrioventricular septal defect repair

OBJECTIVES

Although left ventricular outflow tract (LVOT) obstruction is a recognized risk after atrioventricular (AV) septal defect (AVSD) repair, quantitative assessments to define the substrate of the obstruction are lacking.

METHODS

Morphometric analyses were based on measurements from early 2-dimensional echocardiographic scans (within 3 months postoperatively) for 117 patients (82 CAVVO = common AV valve; 35 SAVVO = separate AV valve orifices), which were compared to 50 age/weight matched controls (atrial septal defect/ventricular septal defect). Late echocardiographic analyses were performed in 57 patients with AVSD (follow-up range, 1.2-10.7 years).

RESULTS

Adequate z scores (above -2.5) were observed in 109 (93%) patients with AVSD at the aortic annulus and in 89 (76%) with AVSD in the subaortic area. Compared to the control group, patients with AVSD had lower median z scores at the aortic annulus (-0.64 vs 0.60; P < 0.001) and the subaortic areas (-1.48 vs 0.59; P < 0.001), disproportionate subaortic/aortic annulus ratio <1.00 (67% vs 22%; P < 0.001), narrower annuloaortic-septal angle (94.0 vs 104.0; P < 0.001) and annuloaortic left AV valve angle (78.0 vs 90.0; P < 0.001). Compared to patients with CAVVO, those with SAVVO had narrower annuloaortic-septal angles (P = 0.022) that persisted at late analysis, with lower subaortic/aortic annular ratios (P = 0.039). In patients with CAVVO, lower early postoperative subaortic z scores were found following modified single-patch repairs (median -2.12 vs -1.02 in two-patch repairs; P = 0.004). A total of 6/117 (5%) patients (4 CAVVO, 5% and 2 SAVVO, 6%) required reoperations for LVOT obstruction (mean 6.9 years postoperatively), with no difference in morphology or types of operations.

CONCLUSIONS

Despite having adequate z scores, patients with AVSD demonstrated abnormal LVOT morphometrics early postoperatively. Besides intrinsic morphology, repair techniques may have an impact on postoperative LVOT morphometrics and requires further evaluation.

Technical Features of Biventricular Repair for Unbalanced Transitional AVSD With LVOTO

Surgical management of left ventricle outflow tract obstruction in infants with right-dominant unbalanced transitional atrioventricular septal defect poses difficulties. A two-month-old infant with transitional atrioventricular septal defect and complex left ventricle outflow tract obstruction presented in cardiogenic shock. The patient underwent successful biventricular repair. The operative procedure included detachment of the anterior bridging leaflet and resection of its chordal attachments. Septal myectomy was performed with creation of an interventricular communication, followed by patch augmentation of the left ventricular outflow tract and anterior bridging leaflet. The zone of apposition between anterior and posterior bridging leaflets was closed. The repair resulted in effective augmentation of the left ventricular inflow and outflow tracts.

Modified single patch: are we still worried about subaortic stenosis?

BACKGROUND

When the modified single-patch technique for atrioventricular septal defect (AVSD) repair was introduced by Dr Benson Wilcox, there was concern that these patients might be at risk for late subaortic stenosis and left ventricular outflow tract obstruction (LVOTO). This review evaluated our modified single-patch population for LVOTO in the postoperative period.

METHODS

Between January 2000 and 2013, 77 infants underwent AVSD repair with a modified single-patch technique. Median age was 4.2 months, and median weight was 5 kg. Eight patients had a prior repair of coarctation of the aorta via left thoracotomy in the newborn period.

RESULTS

The median hospital stay was 10 days. No patient required a pacemaker. The mean and median follow-up times were 4.6 and 3.7 years, respectively. Only 2 patients (2.5%) required reoperation for LVOTO; both had prior repair of coarctation of the aorta (2 of 8 vs 0 of 69, p = 0.01). A discrete fibrous subaortic membrane developed in the first patient that required resection at 3 and 7 years after repair. The other patient had LVOTO from accessory chordae of the left atrioventricular valve and required mitral valve replacement 5 months after repair. One early death occurred at 4 months postoperatively due to liver failure related to hyperalimentation.

CONCLUSIONS

At intermediate term follow-up, LVOTO does not appear to be a significant postoperative issue after modified single-patch repair of AVSD. Coarctation of the aorta was the most significant predictor of late LVOTO after repair of AVSD with the modified single-patch technique.

Reoperation for left ventricular outflow tract obstruction after repair of atrioventricular septal

Left ventricular outflow tract obstruction (LVOTO) is an important source of morbidity and mortality after repair of atrioventricular septal defect (AVSD). The intrinsic anatomy of the left ventricular outflow tract in AVSD is complex and predisposes to the development of LVOTO. LVOTO after repair of AVSD usually involves multiple levels and sources of obstruction, and surgical intervention must address each component of the obstruction. This includes fibromuscular obstruction, septal hypertrophy, and valve related sources of obstruction. Special attention is also directed to the anterolateral muscle bundle of the left ventricle, a well defined but under recognized feature of the left ventricular outflow tract in AVSD. It is present in all patients with AVSD, and resection of a hypertrophic anterolateral muscle bundle of the left ventricle should be incorporated in all operations for LVOTO after repair of AVSD. LVOTO after repair of AVSD has several unique features that must be taken into consideration to maximize outcome after surgical intervention. These include anatomic factors, technical aspects of surgical intervention, and proper selection of the operation used for relief of LVOTO.

Modified Konno procedure: surgical management of tunnel-like left ventricular outflow tract stenosis

Left ventricular outflow tract stenosis represents 1-2 % of all congenital anomalies. In particular, tunnel-like left ventricular stenosis which is one type of fixed left ventricular outflow stenosis requires aggressive surgery to reduce the left ventricular outflow gradient. The purpose of the modified Konno procedure is to release fixed left ventricular outflow tract stenosis while preserving the native aortic valve and its function. Although the clinical results of the modified Konno procedure are acceptable, it is necessary to precisely understand this procedure and the anatomy of the left ventricular outflow tract in order to avoid complications.

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.

The double patch repair for complete atrioventricularis communis

This article is a review of our experience with the two-patch repair of complete atrioventricularis communis. From October 1988 through December 2005, 222 infants and children underwent surgery. There were six early (2.7%) and six late (2.7%) deaths. Reoperation was required in 22 patients (10%) for residual or recurrent mitral regurgitation or stenosis, subaortic stenosis, repair of a ventricular septal defect with or without pulmonary stenosis, placement of a right heart valved conduit, and/or placement of a permanent cardiac pacemaker. All patients survived second operations and no child required early or late mitral valve replacement. The two-patch repair is a reliable surgical technique resulting in low mortality and a low need for reoperation.

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.

Complete atrioventricular canal

Complete atrioventricular canal (CAVC), also referred to as complete atrioventricular septal defect, is characterised by an ostium primum atrial septal defect, a common atrioventricular valve and a variable deficiency of the ventricular septum inflow. CAVC is an uncommon congenital heart disease, accounting for about 3% of cardiac malformations. Atrioventricular canal occurs in two out of every 10,000 live births. Both sexes are equally affected and a striking association with Down syndrome was found. Depending on the morphology of the superior leaflet of the common atrioventricular valve, 3 types of CAVC have been delineated (type A, B and C, according to Rastelli's classification). CAVC results in a significant interatrial and interventricular systemic-to-pulmonary shunt, thus inducing right ventricular pressure and volume overload and pulmonary hypertension. It becomes symptomatic in infancy due to congestive heart failure and failure to thrive. Diagnosis of CAVC might be suspected from electrocardiographic and chest X-ray findings. Echocardiography confirms it and gives anatomical details. Over time, pulmonary hypertension becomes irreversible, thus precluding the surgical therapy. This is the reason why cardiac catheterisation is not mandatory in infants (less than 6 months) but is indicated in older patients if irreversible pulmonary hypertension is suspected. Medical treatment (digitalis, diuretics, vasodilators) plays a role only as a bridge toward surgery, usually performed between the 3rd and 6th month of life.

Repair of Complete Atrioventricular Septal Defect with Tetralogy of Fallot:

OBJECTIVES

The aim of this report is to describe the rationale of our surgical approach, to explore the best management for complete atrioventricular septal defect associated with the tetralogy of Fallot (CAVSD-TOF), and to present our outcome in relation to the previously reported series.

MATERIALS AND METHODS

Between January 1990 and January 2002, 17 consecutive children with CAVSD-TOF underwent complete correction. Nine patients (53%) underwent previous palliation. Mean age at repair was 2.9 +/- 1.9 years. Mean gradient across the right ventricular outflow tract was 63 +/- 16 mmHg. All children underwent closure of septal defect with a one-patch technique, employing autologous pericardial patch. Maximal tissue was preserved for LAVV reconstruction by making these incisions along the RV aspect of the ventricular septal crest. LAVV annuloplasty was performed in 10 (59%) patients. Six patients (35%) required a transannular patch.

RESULTS

Three (17.6%) hospital deaths occurred in this series. Causes of death included progressive heart failure in two patients and multiple organ failure in the other patient. Two patients required mediastinal exploration due to significant bleeding. Dysrhythmias were identified in 4 of 11 patients undergoing a right ventriculotomy versus none of the patients undergoing a transatrial transpulmonary approach (p = ns). The mean intensive care unit stay was 3.2 +/- 2.4 days. Two patients required late reoperation due to severe LAVV regurgitation at 8.5 and 21 months, respectively, after the intracardiac complete repair. The mean follow-up time was 36 +/- 34 months. All patients survived and are in NYHA functional class I or II. The LAVV regurgitation grade at follow-up was significantly lower than soon after operation, 1.1 +/- 0.4 versus 1.7 +/- 0.5 (p = 0.002). At follow-up, the mean gradient across the right ventricular outflow tract was 17 +/- 6 mmHg, significantly lower than preoperatively (p < 0.001).

CONCLUSIONS

Complete repair in patients with CAVSD-TOF seems to offer acceptable early and mid-term outcome in terms of mortality, morbidity, and reoperation rate. Palliation prior to complete repair may be reserved in specific cases presenting small pulmonary arteries or severely cyanotic neonates. The RVOT should be managed in the same fashion as for isolated TOF; however, a transatrial transpulmonary approach is our approach of choice.

Atrioventricular septal defect with tetralogy of Fallot: results of surgical correction

BACKGROUND

The outcome of surgical correction of complete atrioventricular septal defect with tetralogy of Fallot has improved in recent years. Controversy exists about the optimal approach to this complex lesion. Our experience over the past 8 years with a single technique is reviewed. The important anatomic features of this lesion are discussed in relation to our method of repair.

METHODS

Between 1988 and 1996, 11 consecutive patients underwent correction of complete atrioventricular septal defect with tetralogy of Fallot. Nine patients had undergone prior palliative shunts. The two-patch technique for atrioventricular septal defect was used. The ventricular septal defect was closed through a right ventriculotomy in each case. The commissure between the superior and inferior bridging leaflets of the left portion of the common atrioventricular valve was closed in each patient. Management of the right ventricular outflow tract was individualized.

RESULTS

There was one mortality in the early postoperative period. One patient required reoperation for closure of a dehiscent left atrioventricular valve cleft. All survivors are currently in New York Heart Association functional class I or II at follow-up ranging from 2 to 101 months.

CONCLUSIONS

Atrioventricular septal defect with tetralogy of Fallot can be corrected with low mortality using the two-patch technique and closure of the ventricular septal defect through a combined approach using a right ventriculotomy and right atriotomy. Routine closure of the commissure of the left portion of the atrioventricular valve results in a low incidence of regurgitation. A good functional result can be achieved in most patients at intermediate-term follow-up.

Cephalad resuspension of aortic leaflet of the mitral valve in hypertrophic obstructive cardiomyopathy

A young child with hypertrophic obstructive cardiomyopathy, who was reoperated on for recurrent left ventricular outflow tract obstruction, underwent myectomy with patch augmentation of the ventricular septum. Cephalad resuspension of the aortic leaflet of the mitral valve resulted in abolishment of residual obstruction occurring secondary to its systolic anterior motion.

Modified Konno-Rastan procedure for subaortic stenosis: indications, operative techniques, and results

BACKGROUND

Diffuse or unresectable subaortic stenosis (SAS) necessitates an aggressive surgical approach for the elimination of left ventricular outflow tract obstruction. In this article we report our experience with the modified Konno-Rastan procedure, with inherent preservation of the native aortic valve and annulus, in the treatment of diffuse or unresectable SAS.

METHODS

Sixteen children (age range, 21 months to 18 years) underwent the modified Konno-Rastan procedure through either a transventricular (n = 12) or a transatrial approach (n = 4) to the conal septum. Indications for operation were recurrent SAS (n = 3), hypertrophic obstructive cardiomyopathy (n = 3), tunnel stenosis (n = 2), SAS related to a canal (n = 3), and SAS after ventricular septal defect closure (n = 5). Eleven patients had undergone previous procedures and 5 underwent the modified Konno-Rastan procedure as their primary operation.

RESULTS

The mean preoperative left ventricular outflow tract gradient of 50 +/- 17 mm Hg was reduced to 3 +/- 7 mm Hg (p < 0.001) after surgical repair. Postoperative complications included sternal infection (n = 1), heart block (n = 2), mediastinal bleeding (n = 1), and renal and cerebral ischemia (n = 1). There was 1 late postoperative death caused by pneumonia 2 years after operation (6.2% mortality rate). The mean follow-up period was 62 +/- 39 months and all patients had complete relief of preoperative symptoms and were in New York Heart Association class I. One patient underwent a successful redo modified Konno-Rastan procedure 7 years after the first operation for residual left ventricular outflow tract obstruction immediately below the aortic valve. One patient is awaiting reoperation for aortic incompetence unrelated to conal enlargement 1.5 years after the first procedure.

CONCLUSIONS

The modified Konno-Rastan procedure represents an excellent therapy for diffuse or unresectable SAS in patients with a normal aortic valve. In addition, it produces excellent results in a limited number of patients with hypertrophic obstructive cardiomyopathy, in whom the Morrow procedure traditionally has been performed. Although it usually is performed through a transventricular approach, the modified Konno-Rastan procedure also can be performed through a transatrial approach; this is particularly useful in patients who have had previous ventricular septal defect closure associated with SAS occurring proximal to the prosthetic patch.

Morphometric analysis of atrioventricular septal defect with common valve orifice

OBJECTIVES

We sought to analyze morphometric features of atrioventricular septal defect (AVSD) in autopsy specimens and to consider the developmental implications of obstruction in either ventricular outflow tract.

BACKGROUND

Left ventricular outlet obstruction (LVO) is more prevalent in patients with Rastelli type A morphology. When tetralogy of Fallot (ToF) complicates this malformation, there is usually a free-floating superior bridging leaflet. The reasons for these associations are uncertain.

METHODS

In 133 hearts with AVSD and common atrioventricular (AV) valve orifice, we measured the degrees of horizontal and anterior deviation of the great arteries from the AV valve, the diameters of the ventricular outlets and the great arteries and the degree of deficiency of the ventricular septum.

RESULTS

In Rastelli type A morphology, the great arteries were deviated more leftward than in type C morphology (p < 0.01). Type A hearts also had a relatively small aorta, with a long and narrow subaortic tract. The presence of obstruction in either ventricular outlet was associated with a more oblique arrangement of the great arteries, with the pulmonary trunk being more leftward than in hearts without LVO (p < 0.01). In combination with ToF, the aorta was dextroposed and the pulmonary trunk was located more posteriorly (p < 0.01). No heart with type A morphology showed ToF (p < 0.01).

CONCLUSIONS

The geometric arrangement of the great arteries correlated significantly with obstruction in either ventricular outflow tract and with the Rastelli subtypes. Malrotation of the developing outlet septum may be an embryologic factor producing obstruction, with horizontal deviation of the outlets also influencing the morphology of the superior bridging leaflet.

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.

Subaortic stenosis in the spectrum of atrioventricular septal defects. Solutions may be complex and palliative

From July 1982 through September 1994, 19 children had operative treatment of subaortic stenosis associated with an atrioventricular septal defect. Specific diagnosis were septum primum defects in 7, Rastelli type A defects in 6, transitional defects in 4, inlet ventricular septal defect with malattached chordae in 1, and tetralogy of Fallot with Rastelli type C defect in 1. Twenty-seven operations for subaortic stenosis were performed. Surgical treatment of the outlet lesion was performed at initial atrioventricular septal defect repair in 3 children and in the remaining 16 from 1.2 to 13.1 years (mean 4.9 years, median 3.9 years) after repair. Eighteen of the 19 children had fibrous resection and myectomy for relief of obstruction. Seven children had an associated left atrioventricular valve procedure. One child received an apicoaortic conduit. Seven children (36.8%) required 8 reoperations for previously treated subaortic stenosis. Time to the second procedure was 2.8 to 7.4 years (mean 4.9 years). Follow-up is 0.4 to 14.0 years (median 5.6 years). Six-year actuarial freedom from reoperation is 66% +/- 15%. The angle between the plane of the outlet septum and the plane of the septal crest was measured in 10 normal hearts (86.4 +/- 13.7) and 10 hearts with atrioventricular septal defects (22.2 +/- 26.0; p < 0.01). The outflow tract can be effectively shortened, widened, and the angle increased toward normal by augmenting the left side of the superior bridging leaflet and performing a fibromyectomy.

CONCLUSION

Standard fibromyectomy for subaortic stenosis in children with atrioventricular septal defects leads to a high rate of reoperation. Leaflet augmentation and fibromyectomy may decrease the likelihood of reoperation.

Fixed subaortic stenosis in atrioventricular canal defect: a Doppler echocardiographic study

OBJECTIVES

The objectives of this retrospective study were to describe the Doppler and echocardiographic features of fixed subaortic stenosis in the setting of atrioventricular (AV) canal defect and to document the de novo occurrence of subaortic stenosis and progression of this lesion over time on the basis of sequential echocardiographic studies.

BACKGROUND

The coexistence of fixed subaortic and AV canal defect has been sporadically noted, but no single or multicenter experience with this constellation of abnormalities has been previously described.

METHODS

All patients with a diagnosis of subaortic stenosis and complete or partial AV canal defect who had one or more Doppler echocardiographic examinations were identified from a computer data bank. Retrospective analysis was performed, including review of patients' charts, operative notes, recorded videotapes and hard copy recordings when available.

RESULTS

Twenty-one patients with both subaortic stenosis and AV canal defect were identified over a 13-year period. Fifteen were female and the mean age at diagnosis of subaortic stenosis was 16 years. Fifteen patients had partial AV canal defect with prior repair in 10; 6 patients had complete AV canal defect with prior repair in 4. The mean interval from prior repair to recognition of subaortic stenosis was 6.8 years. In six patients, serial examinations demonstrated the de novo occurrence of subaortic obstruction over a period of 10 to 87 months. In five patients, progression of known subaortic stenosis was documented over a 10- to 59-month period. Surgical resection of subaortic stenosis was performed in 16 patients; the echocardiographic diagnosis was confirmed in 15 of the 16.

CONCLUSIONS

In the largest reported echocardiographic series of this lesion complex, it is concluded that subaortic stenosis can occur de novo, is often recognized only after repair of the canal defect and is progressive. Doppler echocardiography is the method of choice for diagnosis and serial follow-up of these patients.

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.

Surgical options in subaortic stenosis associated with endocardial cushion defects

Over a 15-year period, 12 patients with endocardial cushion defects undergoing correction had subaortic stenosis requiring operative intervention. Ages ranged from 4 months to 17 years (mean, 7 +/- 6 years) and subaortic gradients from 15 to 100 mm Hg (mean, 60 +/- 25 mm Hg). Subaortic stenosis was due to discrete fibromuscular tissues in 7 patients, mitral valve malattachment in 3, and tunnel outflow in 2. In 2, the subaortic stenosis was clinically significant at the time of endocardial cushion defects repair, whereas in 10 it was noted 2 to 14 years postoperatively (mean, 6.3 +/- 5 years). Surgical relief of subaortic stenosis was accomplished by resection of muscle tissues in 7, apicoaortic conduit insertion in 2, modified Konno procedure (aortic valve preserved) in 2, and lifting of malattached mitral valve from the outflow in 1. There was no early death and one late death (infected conduit). Severe mitral insufficiency developed in the patient who had the mitral valve lifted and necessitated valve replacement. Postoperative echocardiographic gradient in 9 patients ranged from 0 to 36 mm Hg (mean, 10.5 +/- 14 mm Hg). Clinically significant subaortic stenosis has not developed in any patient in 15 years of follow-up (mean, 5 +/- 4 years). We conclude that in subaortic stenosis associated with endocardial cushion defects, resection is effective for discrete obstruction, whereas a modified Konno procedure is preferable for obstruction due to tunnel outflow or mitral valve malattachment.

Anterolateral muscle bundle of the left ventricle in atrioventricular septal defect: left ventricular outflow tract and subaortic stenosis

The anatomy of the left ventricular outflow tract (LVOT) in 77 hearts with atrioventricular septal defect (AVSD), 36 with a separate A V orifice and 41 with a common A V-orifice, were investigated. In all specimens, an anterolateral muscle bundle of the left ventricle was identified between the superior bridging leaflet and the left coronary aortic cusp. It displaced the attachment of the superior bridging leaflet, resulting in its clockwise rotation. The muscle bundle frequently bulged into the LVOT, but was never prominent enough to have caused significant subaortic stenosis. Measurement of the LVOT aortic ratio was possible in 54 hearts and ranged from 36-100%. In 23 cases (43%), there was mild to moderate subaortic narrowing with a ratio ranging from 53-88%. In six cases (11%), unequivocal subaortic stenosis was present, mainly in AVSD with separate A V orifices (five of six) and iatrogenic in one case with surgically corrected complete defect. A decreased ratio was mainly due to decreased anteroposterior width of the septum in the subaortic area, with anterior displacement of the superior bridging leaflet in cases with dense septal attachment of the superior bridging leaflet (i.e., in AVSD with separate A V orifices, type A complete defect with small ventricular septal defect, or surgically corrected complete defect). Significant subaortic stenosis was caused by hypertrophy of the ventricular septum in the subaortic area with anteroseptal twist in four cases, by anomalous chordal insertion of the superior bridging leaflet in one case, and iatrogenic in one case after surgical correction with left A V valve replacement in type C complete defect.(ABSTRACT TRUNCATED AT 250 WORDS)