What Is the Best Technique for Repair of Complete Atrioventricular Canal?

Anatomic considerations in the management of complete atrioventricular canal

OBJECTIVE

Patients with complete atrioventricular canal have a variable clinical course prior to repair. Many patients balance their circulations well prior to elective repair. Others manifest clinically significant pulmonary over circulation early in life and require either palliative pulmonary artery banding or complete repair. The objective of this study was to assess anatomic features that impact the clinical course of patients.

METHODS

In total, 222 patients underwent complete atrioventricular canal repair between 2012 and 2022 at a single institution. Twenty-seven (12%) patients underwent either pulmonary artery banding (n = 15) or complete repair (n = 12) at less than 3 months of age (Group 1). The remaining 195 (88%) underwent repair after 3 months of age (Group 2). Patient records and imaging were reviewed.

RESULTS

The median post-operative length of stay following complete repair was 25 [7,46] days for those patients in Group 1 and 7 [5,12] days for those in Group 2 (p < 0.0001). There was relative hypoplasia of left-sided structures in Group 1 versus Group 2. Mean z-score for the ascending aorta was -1.2 (±0.8) versus -0.3 (±0.9) (p < 0.0001), the aortic isthmus was -2.1 (±0.8) versus -1.4 (±0.8) (p = 0.005). The pulmonary valve to aortic valve diameter ratio was median 1.47 [1.38,1.71] versus 1.38 [1.17,1.53] (p 0.008).

CONCLUSIONS

Echocardiographic evaluation of the systemic and pulmonary outflow of patients with complete atrioventricular canal may assist in predicting the clinical course and need for early repair vs pulmonary artery banding.

Teaching the Modified Single-Patch Technique for Complete Atrioventricular Septal Defect

Understanding the morphology of atrioventricular septal defects and learning the operative strategies for their repair is one of the more difficult tasks for congenital cardiac surgery residents to master. The modified single-patch technique for several reasons lends itself to being a strategy that is relatively easy to teach residents. It has shorter cross-clamp and bypass times than the standard two-patch technique, which allows more time for the instructor to safely take the resident through the case. The steps of the operation are quite standard and broadly applicable to the wide variety of cardiac morphologies found in children with atrioventricular septal defects. The purpose of this review is to carefully point out the technical details of each step of the modified single-patch technique focusing on teaching the resident surgeon. The ease of teaching this excellent technique is just another reason to use the modified single-patch technique.

Reassessment of the Location of the Conduction System in Atrioventricular Septal Defect Using Phase-Contrast Computed Tomography

The location of the atrioventricular conduction axis in the setting of atrioventricular septal defect has previously been shown by histology and intraoperative recordings. We have now reassessed the arrangement using phase-contrast computed tomography, aiming to provide precise measurements so as to optimize future surgical repairs. We used the system based on an X-ray Talbot grating interferometer using the beamline BL20B2 in a SPring-8 synchrotron radiation facility available in Japan. We analyzed 18 specimens. The atrioventricular node was found within a nodal triangle 1.7 mm from the coronary sinus, with 95% confidence intervals from 1.45 to 2.0 millimeters. The depth of the node from the right atrial endocardium was 1.0 mm, with 95% confidence intervals from 0.73 to 1.34 mm. The overall length of the scooped-out ventricular septum was 30.8 mm, with 95% confidence intervals from 27.5 to 34.1 millimeters. The length from the inferior atrioventricular junction to the take-off of the right bundle branch was 12.8 mm, with 95% confidence intervals from 11.12 to 14.38 mm, giving a ratio of 0.43 for the extent of the axis along the inferior septum, with 95% confidence intervals of 0.38-0.48. The length of the non-branching bundle was 6.6 mm, with 95% confidence intervals from 5.57 to 7.7 mm. The proportion of septum occupied by the non-branching bundle was 0.22, with 95% confidence intervals from 0.18 to 0.26. Our findings confirm previous histological studies, extending them by providing precise measurements to guide placement of sutures during surgical repair.

Left Valvar Morphology Is Associated With Late Regurgitation in Atrioventricular Canal Defect

BACKGROUND

Left atrioventricular valve regurgitation (LAVVR) after atrioventricular canal (AVC) repair remains a significant cause of morbidity. Papillary muscle arrangement may be important. To investigate the implications of left mural leaflet morphology, we examined anatomic characteristics of the LAVV to determine possible associations with postoperative LAVVR.

METHODS

All patients with biventricular AVC repair at our institution between January 1, 2011, and December 31, 2016, with necessary imaging were retrospectively reviewed. We assessed papillary muscle structure and novel measures of the left mural leaflet from preoperative echocardiograms and the degree of LAVVR from the first and last available follow-up echocardiograms. Associations with degree of early and late postoperative LAVVR were assessed with t tests, analysis of variance, or χ² or Fisher exact tests, and multivariable logistic regression.

RESULTS

There were 58 of 156 patients (37%) with significant (moderate or severe) early postoperative LAVVR, and 30 of 93 (32%) had significant LAVVR after 6 or more months. Fewer patients with closely spaced or asymmetric papillary muscles had moderate or severe late LAVVR vs those with widely spaced papillary muscles (17% vs 40%, P = .019). Controlling for weight at operation, genetic syndromes, and bypass time, widely spaced papillary muscles increased the odds ratio for late LAVVR to 3.6 (P = .026). Larger mural leaflet area was also associated with late LAVVR on univariable (P = .019) and multivariable (P = .023) analyses. One-third of patients with significant late LAVVR had no significant early postoperative regurgitation.

CONCLUSIONS

Mural leaflet and papillary muscle anatomy are associated with late LAVVR after AVC repair. Late regurgitation can develop in the absence of early LAVVR, suggesting different mechanisms.

Modified-Single Patch vs Double Patch Repair of Complete Atrioventricular Septal Defects

Biventricular repair of complete atrioventricular septal defect (CAVSD) is largely achieved using the double-patch (DP) or modified single-patch (MSP) techniques in the current era; however, long-term results following MSP repair are not well defined. We aimed to compare long-term outcomes including reoperation and mortality after CAVSD repair using DP and MSP techniques, and identify the risk factors associated with adverse outcomes. A retrospective cohort study was performed including all patients who underwent CAVSD repair using DP and MSP techniques at our institution between 17 May 1990 and 14 December 2015. Demographic details, early (≤30 days) and late (>30 days) outcomes (reoperation, mortality) were studied. Competing risks analysis with cumulative incidence function was used for survival analyses. Overall, 273 consecutive patients underwent CAVSD repair (120 DP and 153 MSP) and 41 patients required reoperation during follow-up. Competing risks analysis showed no association between repair technique and reoperation (P = 1.0) or mortality (P = 0.9). Considering competing risks due to mortality, the cumulative incidence of reoperation at 5, 10, and 15 years was 14%, 17%, and 17% for DP and 12%, 13%, and 16% for MSP, respectively. Non-Down syndrome and moderate or greater left atrioventricular valve regurgitation were predictors for reoperation. Pulmonary artery banding was predictive of mortality, though strongly associated with earlier surgical era. Median follow-up duration was 8.0 years (interquartile range 3.9-20.8) for DP and 11.6 years (interquartile range 5.4-16.1) for MSP (P = 0.4). Event-free survival is similar after DP and MSP repair of CAVSD indicating either repair technique can be safely utilized.

Modified Single-Patch Technique Versus Two-Patch Technique for the Repair of Complete Atrioventricular Septal Defect: A Meta-Analysis

Technical selection for surgical repair of complete atrioventricular septal defect (CAVSD) still remains controversial. This meta-analysis aimed to compare the modified single-patch (MP) technique with the two-patch (TP) technique for patients with CAVSD. Relevant studies comparing the MP technique with the TP technique were identified through a literature search using MEDLINE, EMBASE, Google Scholar, Cochrane Library, and the China National Knowledge Infrastructure databases. The variables were ventricular septal defect (VSD) size, cardiopulmonary bypass (CBP) time, aortic cross-clamp (ACC) time, intensive care unit stay, hospital stay, and other outcomes involving mortality, left ventricular outflow tract obstruction, atrioventricular valve regurgitation, residual septal shunt, atrioventricular block, and reoperation. A random-effect/fixed-effect model was used to summarize the estimates of mean difference/odds ratio with 95% confidence interval. Subgroup analysis stratified by region was performed. Fifteen publications involving 1034 patients were included. This meta-analysis demonstrated that (1) VSD size in the MP group was significantly smaller; (2) CBP time, ACC time, and hospital stay in the MP group experienced improvement; (3) Other postoperative outcomes showed no significant differences between two groups; and (4) The trends in China and other countries were close. The MP and TP techniques had comparable outcomes; however, the MP technique was performed with significantly shorter CBP and ACC times in patients with smaller VSDs. Given this limitation of data, the results of comparison of the two techniques in patients with larger VSDs remain unknown. Further studies are needed.

Complete Atrioventricular Canal Defect: Towards a More Physiological Repair

We describe a more physiological technique of complete atrioventricular septal defect repair which restores normal heart anatomy with the offset between the insertions of the mitral and tricuspid valves. This technique overcomes the drawbacks of the previous approaches, and may improve surgical outcomes, particularly in small infants with high ventricular septal defect component or dextroposed aorta.

Repair of Complete Atrioventricular Septal Defects With Decellularized Extracellular Matrix: Initial and Midterm Outcomes

Objective:

Since April 2010, our institution has repaired complete atrioventricular septal defects (CAVSDs) with a two-patch technique utilizing CorMatrix extracellular material. This material is potentially an attractive patch because of its theorized eventual integration with the host tissue. We sought to analyze initial outcomes of CAVSD repair with CorMatrix.

Methods:

Data were collected on consecutive pediatric (age <18) patients receiving two-patch CAVSD repairs with CorMatrix at a single institution from April 2010 to July 2014. Baseline and perioperative characteristics were evaluated. Echocardiograms were evaluated in both the immediate postoperative period and the most recent postoperative follow-up. Variables analyzed included left AV valve performance, residual shunting, left ventricular outflow tract (LVOT) gradient, morbidity, and mortality.

Results:

Fifteen patients were identified. The average age at operation was 205 days, with mean follow-up time at 1,364 days. Echocardiograms revealed the following: 12 (80%) patients showed either improved or stable left AV valve performance remaining at “mild” or less insufficiency, while two (13%) declined from “none” to mild and one (7%) from mild to “severe,” which required reoperation. There was no residual shunting or LVOT obstruction at follow-up. The single (7%) reoperation was performed after three years due to left AV valve zone of apposition dehiscence. No permanent pacemakers were needed, and no deaths were reported.

Conclusion:

Our initial experience with CorMatrix in the repair of CAVSD in children has resulted in good initial and midterm outcomes. The CorMatrix patch remained stable through midterm follow-up, thus may be efficacious for use in CAVSD repair.

Surgical repair of complete atrioventricular defect (Nunn technique)

Two procedures have been traditionally used for the surgical repair of complete atrioventricular canal. The single-patch technique includes the division of valve leaflets, and the use of one patch to close the ventricular and the atrial septal defects, whereas the double-patch technique uses two separate patches, without the division of the bridging leaflets. Between 1997 and 2007, another technique emerged, the modified single-patch technique, or the 'Australian' technique, whereby the ventricular septal defect (VSD) is closed by the direct apposition of the bridging leaflets against the crest of the defect. Because of the absence of the ventricular septal patch, concerns have been raised about the possible left ventricular outflow tract obstruction (LVOTO), or atrioventricular valve (AVV) distortion, especially in case of a deep VSD, or if the defect extends superiorly. The results of the modified single-patch technique in terms of mortality, immediate and long-term AVV function and LVOTO have been similar to the standard techniques in most reports. This article will describe in detail the operative technique and review the relevant literature.

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.

A Novel Technique for Repair of Complete Atrioventricular Canal Defect

Background:

Two-patch, single-patch, and modified single-patch repairs are accepted techniques for repair of complete atrioventricular (AV) canal defects. We propose a novel, alternative technique: the central patch technique.

Methods:

For the central patch technique, the superior and inferior bridging leaflets are attached with simple sutures to the right and left of their coaptation point. Both bridging leaflets are incised along a line above the ventricular crest, similar to a traditional single-patch technique. An oval pericardial patch is sewn to the central defect created in the AV valve tissue. Interrupted, horizontal mattress sutures are placed along the ventricular crest, through the midline of the central patch and through the edge of the atrial septal defect (ASD) patch. Tying the sutures simultaneously closes the ventricular septal defect (VSD) and secures the ASD patch to the ventricular crest. Repair of the left AV valve and ASD closure are performed in the routine fashion.

Results:

Five patients underwent the central patch technique repair of complete AV canal defect. Weight was 4.8 to 6.3 kg; age was four to eight months. Cardiopulmonary bypass and myocardial times averaged 137 minutes and 109 minutes, respectively. No patient had more than mild left AV valve regurgitation or trivial residual VSD at completion of repair. No patient developed left ventricular outflow tract obstruction.

Conclusion:

The central patch technique is applicable to all forms of complete AV canal defect. Subjectively, it offers technical advantages compared to standard techniques and may result in a shorter learning curve for junior congenital heart surgeons. Results are preliminary but are consistent with standard techniques.

Management of Complete Atrioventricular Canal Defect With Aortic Arch Obstruction

Patients with complete atrioventricular canal defect and aortic arch obstruction represent a particular challenge for management. The incidence is rare, so surgical experience is limited. A reasonable treatment option for newborns and young infants with competent atrioventricular valves is the staged approach, with the arch obstruction repaired first, followed at an appropriate interval by repair of the complete atrioventricular canal defect. If there is a significant degree of atrioventricular valve regurgitation, the primary single-stage correction of both aortic arch obstruction and the intracardiac malformation should be undertaken, irrespective of age. It remains to be seen whether this surgical strategy can be adopted for the entire spectrum of atrioventricular canal defect associated with arch obstruction.

Complete atrioventricular canal in a dog

This report details a case of complete, type A atrioventricular (AV) canal, also called complete endocardial cushion defect, in a young dog. Complete AV canal is classified as three types: A, B or C depending on the degree of linkage between common AV valve and ventricular chambers. Despite the defect this dog, which did not undergo surgical treatment, remains in ISACHC class Ib 19 months after the initial diagnosis.