Left ventricular outflow tract obstruction in atrioventricular septal defects: a pathologic and morphometric evaluation

Mitral valve orifice area predicts outcome after biventricular repair in patients with hypoplastic left ventricles

BACKGROUND

Identification of risk factors for biventricular (BiV) repair in children with hypoplastic left ventricles (HLV) has been challenging. We sought to identify preoperative cardiovascular magnetic resonance (CMR) predictors of outcome in patients with HLVs who underwent BiV repair, with a focus on the mitral valve (MV).

METHODS

Single-center retrospective analysis of preoperative CMRs on patients with HLV (≤50 mL/m2) and no endocardial fibroelastosis who underwent BiV repair from 2005-2022. CMR measurements included MV orifice area in diastole. The primary composite outcome included time to death, transplant, BiV takedown, heart failure admission, left atrial decompression, or unexpected reoperation; and the secondary outcome included more than or equal to moderate mitral stenosis and/or regurgitation.

RESULTS

Median follow-up was 0.7 (interquartile range 0.1, 2.2) years. Of 122 patients [59 atrioventricular canal (AVC) and 63 non-AVC] age 3 ± 2.8 years at the time of BiV repair, freedom from the primary outcome at 2 years was 53% for AVC and 69% for non-AVC (log rank p = 0.12), and freedom from the secondary outcome at 2 years was 49% for AVC and 79% for non-AVC (log rank p < 0.01). Independent predictors of primary outcome for AVC patients included MV orifice area z-score <-2 and transitional AVC; for non-AVC patients, predictors included MV orifice area z-score <-2, abnormal MV anatomy, and conal-septal ventricular septal defect. Independent predictors of secondary outcome for AVC patients included older age at surgery, transitional AVC, and transposition of the great arteries.

CONCLUSION

In children with HLV, low MV orifice area and pre-existing MV pathology are risk factors for adverse outcome after BiV repair.

The impact of surgical repair on left ventricular outflow tract in atrioventricular septal defect with common atrioventricular valve orifice

Objective

Although a narrow left ventricular outflow tract in atrioventricular septal defect is related to its intrinsic morphology, the contribution from the repair technique remains to be quantified.

Methods

A total of 108 patients with an atrioventricular septal defect with a common atrioventricular valve orifice were divided into 2 groups: 2-patch (N = 67) and modified 1-patch (N = 41) repair. The left ventricular outflow tract morphometric was analyzed by quantifying the degree of disproportion between subaortic and aortic annular dimensions (disproportionate morphometrics ratio was defined as ≤ 0.9). Z-scores (median, interquartile range) were further analyzed in a subset of 80 patients with immediate preoperative and postoperative echocardiography. A total of 44 subjects with ventricular septal defects served as controls.

Results

Before repair, 13 patients (12%) with an atrioventricular septal defect had disproportionate morphometrics (vs 6 [14%] ventricular septal defect P = .79), but the subaortic Z-score (-0.53, -1.07 to 0.06) was lower than the ventricular septal defect (0.07, -0.57 to 1.17; P < .001). After repair, both 2-patch (8 [12%] preoperatively vs 25 [37%] postoperatively; P = .001) and modified 1-patch (5 [12%] vs 21 [51%], P < .001) procedures showed a greater degree of disproportionate morphometrics. Both 2-patch (postoperatively -0.73, -1.56 to 0.08 vs preoperatively -0.43, -0.98 to 0.28; P = .011) and modified 1-patch (-1.42, -2.63 to -0.78 vs -0.70, -1.18 to -0.25; P = .001) procedures also demonstrated lower subaortic Z-scores postrepair. The postrepair subaortic Z-scores were lower in the modified 1-patch group (-1.42 [-2.63 to -0.78]) compared with the 2-patch group (-0.73 [-1.56 to 0.08]; P = .004). Low postrepair subaortic Z-scores (<-2) were observed in 12 patients (41%) in the modified 1-patch group and 6 patients (12%) in the 2-patch group (P = .004).

Conclusions

Surgical correction resulted in greater disproportionate morphometrics seen immediately postrepair. The impact on the left ventricular outflow tract was observed in all repair techniques, with a greater burden seen after modified 1-patch repair.

Video Abstract

This morphometric study in AVSD with common atrio-ventricular valve orifice confirmed further derangements of LV outflow tract morphometrics immediately after surgical repair.

Case Report: Using Medtronic AP360 mechanical prosthesis in mitral valve replacement for patients with mitral insufficiency after primum atrial septal defect repair to reduce left ventricular outflow tract obstruction risk

Background

Atrial septal defect is one of the most common congenital heart diseases in adults. Primum atrial septal defect (PASD) accounts for 4%-5% of congenital heart defects. Patients with PASD frequently suffer mitral insufficiency (MI), and thus, mitral valvuloplasty (MVP) or mitral valve replacement (MVR) is often required at the time of PASD repair. Unfortunately, recurrent unrepairable severe mitral regurgitation can develop in many patients undergoing PASD repair plus MVP in either short- or long-term after the repair surgery, requiring a re-do MVR. In those patients, the risk of left ventricular outflow tract obstruction (LVOTO) has increased.

Case presentation

We present five such cases, ranging in age from 24 to 47 years, who had a PASD repair plus MVP or MVR for 14-40 years while suffering moderate to severe mitral regurgitation. Using Medtronic AP360 mechanical mitral prostheses, only one patient experienced mild LVOTO.

Conclusions

The use of Medtronic AP360 mechanical mitral prostheses to perform MVR in patients with MI who had a history of PASD repair can potentially reduce the risk of LVOTO. Long-term follow-up is required to further confirm this clinical benefit associated with AP360 implantation in patients with PASD.

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.

Perioperative and Anesthetic Considerations in Atrioventricular Septal Defect

Atrioventricular septal defect results from a failure of normal endocardial cushion fusion during embryologic cardiac development. This developmental aberration results in defects in the atrial and/or ventricular septum and malformation of the atrioventricular valves. The pathophysiology of atrioventricular septal defect is variable, and ranges from mild left to right shunting similar to a simple atrial septal defect to complex single-ventricle heart disease. This review focuses on the spectrum of atrioventricular septal defect from partial to complete, without associated cardiac defects.

Subaortic Area at Risk for Development of Obstruction After Surgical Repair of Atrioventricular Septal Defect: Myth or Reality?

BACKGROUND

Morphology of the left ventricular outflow tract (LVOT) in atrioventricular septal defects (AVSDs) has been reported to be at risk for development of obstruction. The purpose of the present study was to identify the incidence, the risk factors, and the surgical outcomes of subaortic stenosis in repaired AVSDs.

METHODS

Records of 427 consecutive patients who underwent anatomical repair for all types of AVSDs from January 2000 to December 2012 were reviewed. Outcomes, independent risk factors, reoperation, and death were analyzed.

RESULTS

In a median follow-up of five years (range: 17 months-11.8 years), eight patients required nine reoperations for subaortic stenosis. Study group (n = 11) included three additional patients for whom repair was performed in a different institution. Median delay for reoperation was 11.9 years (range: 1.3-19.4 years). Surgical relief of subaortic stenosis was obtained by means of the enlargement of the LVOT: resection of fibrous structures in all reoperated patients and associated with septal myectomy in four. Two patients required a modified Konno procedure. Five reoperations were associated with left atrioventricular valve repair or replacement. Statistical analysis didn't reveal any morphologic or demographic risk factors. No early or late death occurred.

CONCLUSION

The development of subaortic stenosis after repair of AVSD remains a rare complication in midterm follow-up (incidence: 1.9%). The performance of preventive gesture during repair seemed to be unjustified. The surgical management of this reoperation consists of a simple and safe procedure.

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.

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.

Reoperations After Repair of Partial and Complete Atrioventricular Septal Defect

The most common cause of reoperation following repair of atrioventricular septal defect (AVSD) is left atrioventricular valve regurgitation. However, reoperation for subaortic obstruction is required in some, especially after initial repair of partial AVSD. Etiology of reoperation and late outcome were evaluated. Between 1962 and 2007, 146 patients (59 male) underwent reoperation at the authors' institution after prior repair of partial (n = 96) and complete (n = 50) AVSD. Median age at reoperation after repair of partial AVSD was 26 years (range, 10 months to 71 years) and 4.5 years (range, 53 days to 38 years) after repair of complete AVSD. The 3 most common indications for reoperation included left atrioventricular (AV) valve regurgitation in 105 patients, subaortic stenosis in 29, and right AV valve regurgitation in 21. The most common procedures performed included left AV valve repair in 59 (40%) patients, left AV valve replacement in 56 (38%), subaortic fibrous resection/myectomy in 24 (16%), and right AV valve surgery in 19 (13%). Freedom from subsequent reoperation at 10 years was 48% after initial repair of complete AVSD and 84% after initial repair of partial AVSD. During late follow-up, 10-year actuarial survival was 91% and 77% after initial repair of complete and partial AVSD, respectively. The most common indication for reoperation after initial repair of partial or complete AVSD is left AV valve pathology; left ventricular outflow tract obstruction was more common in partial AVSD. Although freedom from subsequent reoperations is higher after initial repair of partial AVSD, these patients have reduced long-term survival when compared with complete AVSD.

Electrophysiologic and anatomical relationships studied in primum atrioventricular septal defect

Anatomy and pattern of electrical activation predict the function and contraction pattern of the heart. Patients with primum atrioventricular septal defect (primum AVSD) present with abnormality of both anatomical arrangements and electric activation and serve therefore as an interesting population for studying electro-anatomic relationships in the heart. Understanding the relationships between anatomic and electrophysiologic abnormality is appropriate not only for diagnosis, therapy, and prognosis in patients with primum AVSD but also for understanding the developmental relationship between the conduction system and heart structures, in general. This article presents a review of the anatomical and electrophysiologic characteristics of patients with primum AVSD and provides recent knowledge of electroanatomical relationships of the heart.

Near miss sudden cardiac death on a young patient with repaired atrioventricular septal defect

Patients with congenital heart disease often face the prospect of long-term haemodynamic or arrhythmic complications for which lifelong follow-up in specialist adult congenital heart disease (ACHD) centres is required. We describe the case of a 25-year-old man with repaired atrioventricular septal defect who was referred to our centre after a ventricular fibrillation arrest. Serial echocardiograms in previous years had shown progressive severe left ventricular outflow obstruction, but the patient had not been operated on as he was deemed asymptomatic and reluctant to consider surgery. Management and criteria for further intervention in ACHD patients often differ from those of patients with acquired heart disease and reliance on symptoms alone is not good practice and may prove catastrophic.

Partial atrioventricular canal: pitfalls in technique

Partial atrioventricular (AV) canal represents approximately 25% of all AV septal defects. While often grouped with secundum ASD from the perspective of cardiopulmonary physiology, clinical presentation, and timing of surgical correction, their optimal management truly requires an understanding of their anatomic similarities to other forms of common AVC defects. By most measures, outcomes for surgical management of partial AV canal has improved over the last four decades, though some aspects of these defects continue to pose important challenges. Current experience has witnessed the reduction in early mortality and only rare complete heart block. Left AV valve dysfunction remains the most common indication for reoperation (10%) with LVOT stenosis the next most common reason (10% to 15% incidence, 5% to 10% reoperation rate). It is important to understand in this population that postoperative left AV valve problems and LVOT stenosis may be intimately linked, both from an etiologic standpoint, and with respect to their management.

Complex atrioventricular canal

Complex forms of atrioventricular (AV) canal (C) such as; AVC with left ventricular outflow tract obstruction, tetralogy of Fallot with complete AVC, double orifice left AV valve, unbalanced complete AVC, and single ventricle patients with common AVC valve require careful preoperative planning and special techniques. This review will explore these technical modifications and outcomes for repair of complex variants of AVC. Optimal results will be achieved using an individually tailored approach that is guided by careful evaluation of the preoperative studies, precise operative technique, and intraoperative assessment of the reconstructed AV valve, as well as a willingness to re-intervene should the postoperative course not proceed as anticipated.

Real-time transthoracic three-dimensional echocardiography provides additional information of left-sided AV valve morphology after AVSD repair

AIMS

The purpose of this study was to assess the feasibility of real-time 3D echocardiography (RT-3DE) data acquisition in adult patients after atrioventricular septal defect (AVSD) repair and to evaluate whether RT-3DE has additional value over 2D echocardiography, regarding morphology and function of the left-sided AV valve (LAVV).

METHODS

Twenty consecutive patients with surgically corrected partial or complete AVSD were enrolled in this study. The 3DE data sets were acquired with the Hewlett-Packard Sonos 7500 echo system (Philips Medical Systems, Andover, MA, USA). Images were reviewed off-line with assistance of TomTec Echoview 5.2 software (TomTec Inc., Munich, Germany) by experienced observers. En face reconstructions, from, respectively, the ventricular and atrial view, were made to evaluate the LAVV morphology and motion.

RESULTS

3DE reconstruction of the LAVV was feasible in 17 of 20 patients (85%). Mean time of 3DE acquisition was 9+/-6 min. The quality of the 3DE images was optimal in 35%, good in 30%, sufficient in 20% and insufficient in 15%. Identification of the LAVV structures was importantly better facilitated from a ventricular view. Accurate identification of LAVV morphology was possible in all 17 patients (85%). Relationship of the LAVV and the abnormal position of the LVOT was easier to evaluate from the 3DE reconstructions than from 2D echo.

CONCLUSION

This study demonstrate that RT-3DE is feasible in daily practice and provides new insight into the dynamic morphology of the left-sided AV valve and LVOT anatomy after AVSD repair.

Morphometric evaluation of the cardiac ventricular capacity of anencephalic fetuses

Anencephaly occurs in 1:1,000 to 1:20,000 infants who are potential donors in pediatric heart transplantation, so it is important to define any morphologic differences between the anencephalic and normal heart in newborns. The dimensions of the heart in anencephalics, however, may differ. For example, the absence of cerebral tissue in anencephalic fetuses may decrease the heart load resulting in a smaller heart. The position of the heart in the thoracic cavity of an anencephalic fetus may affect the size and shape of the heart. This study compares the ventricular volumes and the inlet and outlet lengths of right and left ventricles in 11 normal and 11 anencephalic fetuses of gestational ages between 27 and 35 weeks. There was no statistically significant difference between the right ventricular volumes of normal and anencephalic fetuses, however, the difference between the left ventricular volumes was found to be almost statistically significant (P = 0.07). No statistically significant difference was found between the right and left ventricular volumes of normal fetuses; in anencephalic fetuses left ventricular volumes were found to be significantly smaller than right ventricular volumes (P = 0.05). The outlet length of the right ventricle and the inlet and outlet lengths of left ventricle in anencephalic fetuses were found to be short in comparison with those of normal fetuses (P = 0.01, P = 0.008, P = 0.01). It is proposed that anencephalics, because of these morphologic differences, should be reconsidered as possible donors for heart transplantation.