Mitral valve operations at a high-volume pediatric heart center: Evolving techniques and improved survival with mitral valve repair versus replacement

The Fate of Mitral Valve Surgery in the Pediatric Age: A 25-Year Single-Center Experience

Background: The aim of this study was to evaluate the natural history of patients after mitral valve intervention in the pediatric age. Methods: This is a retrospective study including all patients who underwent mitral valve surgery from 1998 to 2022. The patients' surgical reports, postoperative records, and ambulatory visits were reviewed. The endpoints of the study were survival and freedom from mitral valve reoperation. Results: Of the 70 patients included in the cohort, 61 patients (86.7%) had congenital mitral valve disease, of whom 46 patients (75.4%) had a predominantly mitral regurgitation lesion, and 15 patients (24.6%) had a predominantly mitral stenosis. In the mitral regurgitation group, all of the patients underwent valve repair with an operative mortality of one patient (2.1%), and with median follow-up of 4 years (range, 0.5-13 years), there was 4.3% mortality (n = 2) and 71.2% freedom from reoperation. In the mitral stenosis group, 11 patients underwent mitral valve repair, and 4 patients underwent valve replacement. There was an operative mortality of two patients (13.3%). With a 2-year median follow-up (range: 0.1-23 years), there were no additional mortality cases in the mitral stenosis group. All three patients who survived primary mitral valve replacement (100%) and four patients who survived a primary repair (40.0%) underwent reoperation. Conclusions: This study demonstrates encouraging outcomes for mitral valve repair. The mortality of patients with congenital mitral valve disease may also be related to a difficult postoperative course, rather than the MV lesion itself.

Surgical Melody Mitral Valve: A Paradigm Shift for Infants With Unrepairable Mitral Valve Disease

BACKGROUND

The Melody valve (Medtronic, Minneapolis, MN) for mitral valve replacement (MVR) (MelodyMVR) has been an effective strategy to treat unrepairable mitral valve disease in small children. This study analyzed survival, durability, and complications of the MelodyMVR strategy.

METHODS

Patients who underwent MelodyMVR between 2014 and 2023 were included. Transplant-free survival was analyzed with Kaplan-Meier analysis. The Fine and Gray subdistribution method was applied to quantify the cumulative incidence.

RESULTS

Twenty-five patients underwent MelodyMVR. Median age and weight were 6.3 months (interquartile range, 4.4-15.2 months) and 6.36 kg (interquartile range, 4.41-7.57 kg). Fifteen patients (60%) had congenital mitral valve disease and 13 (52%) had dominant mitral regurgitation. The median diameter of the implanted Melody was 16 mm (interquartile range, 14-18 mm). Mortality at 6 months, 1 year, and 5 years was 8.3% (95% CI, 2.2%-29.4%), 12.5% (95% CI, 4.2%-33.9%), and 17.6% (95% CI, 7.0%-40.7%), respectively. Two hospital survivors (8%) required early Melody replacement. Competing risk analysis showed that ∼50% of patients underwent mechanical MVR by 3.5 years after MelodyMVR. Freedom from bleeding and thrombosis at 4 years was 87.5% (95% CI, 74.2%-100%). Eleven patients underwent subsequent mechanical MVR with no deaths. One (9%) required pacemaker implantation after mechanical MVR.

CONCLUSIONS

MelodyMVR provides reasonable early and medium-term survival in small children and a high rate of successful bridge to mechanical MVR. MelodyMVR is associated with minimal pacemaker requirement, bleeding, and thrombosis. Early Melody functional deterioration necessitates early repeat MVR, which can be achieved with minimal morbidity and mortality.

Fiberscope-Based Measurement of Coaptation Height for Intraoperative Assessment of Mitral Valve Repair

BACKGROUND

Restoring adequate coaptation height is a key principle of mitral valve (MV) repair. This study aimed to evaluate the utility of fiberscope (FS) technology to assess MV coaptation height for intraoperative use.

METHODS

Ex-vivo testing was performed on five adult porcine hearts. The left atrium (LA) was resected, and the left ventricle (LV) was pressurized retrograde to 27 ± 1mm Hg. An endoscope was inserted into the LV apex, centered under the MV orifice. An FS system (Milliscope II camera, LED light source, and 0.7 mm diameter × 15 cm long) 90° semirigid scope with 1.2 mm focal length) was mounted above the MV annulus in a custom alignment and measuring fixture. Three blinded measurements were taken at two locations on each MV, A2 and P2 segment, from the top of coaptation to the leaflet edge identified by the FS. Accurate positioning was verified using the LV endoscope. A control (metal rod of similar thickness) was used for comparison, with coaptation height recorded when the control was seen via the endoscope.

RESULTS

Coaptation heights were similar for the control and FS methods across all hearts at A2 (11.6 ± 2.6 mm control vs 11.8 ± 2.2 mm FS) and P2 (13.3 ± 2.6 mm control vs 13.4 ± 2.9 mm FS) segments, with similar measurement variability (control SD 0.1-1.0 mm; FS SD 0.1-0.9 mm). One outlier was excluded from analysis (n = 19/20). The maximum absolute difference and percent error between measurement methods were less than 1.1 mm (median [IQR], 0.6 [0.3-0.9] mm) and less than 14% (4.1 [2.2-7.6]%).

CONCLUSIONS

Utilization of a miniaturized FS enabled precise and accurate quantification of MV coaptation. This technique is promising for evaluating post-repair valve competence and coaptation height.

Posterior Annulus Elevation Technique in Reducing Residual Regurgitation During Mitral Valve Repair in Children: A Randomized Controlled Trial

Background: The current technique used in severe mitral regurgitation in children can occasionally lead to residual regurgitation. To address this issue, the posterior annulus elevation technique was developed to enhance coaptation and reduce residual lesions. This study aims to evaluate the effectiveness of this technique in reducing residual regurgitation during mitral valve repair in children. Methods: A total of 64 patients aged <18 years old undergoing mitral valve repair were randomized into two groups: the intervention (with posterior annulus elevation) group and the control group, which underwent conventional repair techniques. Various parameters, including coaptation area, residual mitral regurgitation, clinical outcomes, metabolic, and hemolytic markers, were measured on days 0, 5, 2 weeks, and 3 months after surgery. Results: The intervention group (n = 32) showed a significant reduction in residual mitral regurgitation compared with the control group (n = 32) on each evaluation. At three months after surgery, we found that the posterior annulus elevation technique could be a protective factor that reduces the chance of residual regurgitation compared with the control group (RR = 0.31; confidence interval: 0.18-0.54; P ≤ .001). Coaptation length and index were also found to be significantly higher in the intervention group (P ≤ .001). Clinical outcomes, metabolic markers, and hemolysis marker did not show any significant differences between the two groups. Conclusions: The posterior annulus elevation technique demonstrated effectiveness in reducing residual mitral regurgitation and improving coaptation area in pediatric mitral valve repair. This technique showed better short-term surgical outcomes in children with mitral regurgitation compared with the conventional technique.

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.

National In-Hospital Outcomes of Mechanical Mitral Valve Replacement in the Pediatric Population

Background: National data about the outcomes of children undergoing mechanical mitral valve replacement (m-MVR) are scarce. Methods: A retrospective review of hospitalizations from the Kids' Inpatient Database was performed for patients ≤18 years of age in the United States. A total of 500 patients underwent m-MVR in 2009, 2012, 2016, and 2019. Patients with single ventricle physiology were excluded (n  =  13). These patients were categorized into three groups according to age: neonates (<1 month, n  =  20), infants (1-12 months, n  =  76 patients), and children (1-18 years, n  =  404). Outcomes were compared between the three groups. Results: The proportion of m-MVR involving children undergoing MV procedures (repair and replacement) has increased from 17.3% in 2009 to 30.8% in 2019 (Ptrend < .01). History of cardiac surgery was present in 256 patients (51.2%). Concomitant procedures were performed in 119 patients (23.8%). Intra- or postoperative extracorporeal membrane oxygenation was required in 19 patients (3.8%). The overall in-hospital mortality was 4.8% and was significantly higher in neonates and infants compared with older children (10% vs 11.8% vs 3.2%, P = .003). The length of hospital stay was longer in the neonatal group (median, 57 days, interquartile range, [24.8-90] vs 29.5 days [15.5-61] vs 10 days [7-18], P < .01). Nonhome discharges were more common in neonates and infants (40% vs 36.8% vs 13.1%, P < .01). Conclusion: Mechanical mitral valve replacement is increasingly performed over time with acceptable in-hospital morbidity and mortality, especially in older children and adolescents. Neonates and infants are associated with worse hospital survival, prolonged hospitalization, and significant rates of nonhome discharges.

Risk factors for mitral valve dysfunction, reoperation and death following repair of the primary mitral valve disease in children

Background

After primary mitral valve (MV) repair, residual mitral valve regurgitation (MR) and recurred mitral valve stenosis (MS) are the principal occurrences. This study's purpose is to identify the risk factors of MV dysfunction, reoperation and death following repair of primary MV diseases.

Methods

We retrospectively reviewed 98 patients (47 males and 51 females) with primary MV diseases between January 2013 and December 2021. The median age was 34 months [interquartile range (IQR), 11.4-59] for male and 24 months (IQR, 7.35-72) for female. The left ventricular ejection fraction (LVEF), the left ventricular end-diastolic volume index (LVEDVI) and left ventricular end-systolic volume index (LVESVI) were assessed to evaluate patient's left ventricular function. Risk factors that increased the likelihood of MV dysfunction, reoperation and death after surgery were investigated.

Results

During the 23.5 months (IQR, 9-44.5) of follow-up, 5 (5.1%) patients died, including one early death and two late deaths (n=3; 3.9%) in the MR group and one early death and one late death (n=2; 9.1%) in the MS group. Seven (9.2%) patients in the primary MR disease group and 2 (9.1%) patients in the primary MS disease group required a second MV operation for a total reoperation rate of 9.2% (9/98). As of the most recent follow-up, 34 patients experienced MV dysfunction. No significant difference was recorded between primary MR and MS disease groups in Kaplan-Meier freedom from MV dysfunction and reoperation. Mixed MV pathology (P=0.014) acted as an independent risk factor for MV dysfunction, and ≥ moderate MR at 24 h after first surgery (P=0.014) an independent risk factor for MV reoperation. Double-orifice MV technique (P=0.002), MV reoperation (P=0.023) and severe MR at 24 h after first surgery (P=0.028) were independent risk factors for death.

Conclusions

The Kaplan-Meier freedom from MV dysfunction and reoperation were comparable between primary MR and MS disease groups. A high probability of MV dysfunction was predicted due to the mixed MV pathology. Patients with ≥ moderate MR at 24 h after first surgery had a higher risk of MV reoperation. Double-orifice MV technique, MV reoperation and severe MR at 24 h after first surgery had a higher risk for death.

Considerations of valvular heart disease in children with ventricular assist devices

Ventricular assist devices have become a valuable tool in the treatment of heart failure in children. The use of ventricular assist devices has decreased mortality in children with end-stage heart failure awaiting transplant. It is not uncommon for children with end-stage heart failure associated with cardiomyopathy or congenital heart disease to have significant systemic semilunar and atrioventricular valve regurgitation, which can impact the efficiency and efficacy of hemodynamic support provided by a ventricular assist device. Therefore, implanting clinicians should carefully assess for valve abnormalities that may need repair and impact device selection and cannulation strategy to effectively support this diverse population. The purpose of this review is to provide an overview of this important and relevant topic and to discuss strategies for managing these patients.

Predictors of survival in paediatric mitral valve replacement

OBJECTIVES

The aim of this study was to identify the predictors of death and of reintervention after mitral valve replacement (MVR) in children.

METHODS

A single-centre retrospective study was performed including 115 patients under the age of 18 undergoing MVR between 1982 and 2019. For all patients, the ratio of prosthetic valve size (diameter in mm) to weight (kg) at surgery was calculated and long-term result was assessed. The primary outcome was freedom from mitral valve (MV) re-replacement. The composite secondary outcome was freedom from death or transplant.

RESULTS

Fifty-four patients had a previous surgical attempt to MV repair. The median age at surgery was 5.5 years (interquartile range 1.21-9.87). Death/transplant-free survival was 77 ± 4% at 5 years and 72 ± 5% at 10 years. Univariate analysis showed a size/weight ratio higher than 2 and age <2 years as significant risk factors for death or transplant. Freedom from MV re-replacement at 5 and 10 years was 90 ± 3% and 72 ± 6%, respectively. Biological prosthesis implanted at first replacement (P = 0.007) and size/weight ratio higher than 2 (P = 0.048) were predictors of reoperation. Significant upsizing (P < 0.0001) of mitral prosthesis was observed at re-replacement.

CONCLUSIONS

MVR is a viable strategy in children with unrepairable MV disease. Mortality can be predicted based on size/weight ratio and age <2 years. MV re-replacement can be performed with low morbidity and mortality and a larger-size prosthesis can often be placed at the time of redo.

Mitral valve replacement in infants and younger children

Data on mitral valve replacement (MVR) in young children is still limited. Our objective was to evaluate MVR in children below 5 years and identify factors affecting the outcomes. This retrospective study included 29 patients who had MVR from 2002 to 2020. We grouped the patients into two groups according to their age: age ≤ 24 months (n = 18) and > 24 months (n = 11). Primary cardiac diagnoses were Shone complex (n = 7; 24%), isolated congenital mitral valve abnormality (n = 11; 38%), and complete atrioventricular septal defect (n = 3; 10%). The median age was 19 month (25th–75th percentile: 11–32) and 59% were females (n = 17). The hemodynamic lesions were mitral regurgitation in 66%, mitral stenosis in 10%, and combined mitral stenosis and regurgitation in 24% of the patients. St. Jude mitral valve was the most common valve implanted (n = 19, 66%), followed by CarboMedics in 21% of the patients (n = 6). The mitral valve was implanted in the supra-annular position in 6 cases (21%). Preoperative and operative data were comparable between both groups. There was no association between valve size and position with postoperative heart block (P > 0.99, for both). The median follow-up duration was 19.4 months (8.6–102.5). Nine patients had mitral valve reoperation, six had MVR, and three had clot removal from the mitral valve. There was no effect for age group on reoperation (SHR 0.89 (95% CI 0.27–2.87), P = 0.84). Valve size significantly affected reoperation (SHR 0.39 (95% CI 0.18–0.87), P = 0.02). The supra-annular position was associated with an increased risk of reoperation (SHR 3.1 (95% CI 1.003–9.4), P = 0.049). There was no difference in survival according to the age (Log-rank P = 0.57) or valve size (Log-rank P = 0.66). Mitral valve replacement in children is associated with low morbidity and mortality. The risk of reoperation could be affected by the valve size and position rather than the age.

Acute and Short-Term Outcomes of Percutaneous Transcatheter Mitral Valve Replacement in Children

[Figure: see text].

Debate - Replacement of the Mitral Valve Under One Year of Age: Mechanical Valves Should Be Used

This article reviews the literature, focusing on publications from the third millennium and the results of mitral valve replacement in children younger than 1 year of age. Special consideration has been given to neonatal and infant valve replacement to provide insights into valve choice and technique. Mitral valve replacement is an important topic because it carries the highest mortality and poorer long-term prognosis than any other valve replacement in children.

Cylinder mitral and tricuspid valve replacement in neonates and small children

OBJECTIVES

Atrioventricular valve replacement in small children is associated with high morbidity and mortality. There are no prostheses available with a diameter ˂15 mm. This study reports our initial experience with a cylinder valve for mitral and tricuspid valve replacement in infants and small children.

METHODS

Our cylinder valve was hand-made for patients requiring atrioventricuclar valve replacement with an annulus of <15 mm. A 12-mm Contegra valve was prepared and placed inside a 14-mm Gore-Tex tube graft and sutured on both extremities.

RESULTS

Eight patients were included, with a median age of 6.9 months (range 1 day to 38 months). Four had mitral and 4 had tricuspid valve replacement. All implants were technically successful, with no significant regurgitation, no stenosis and no left ventricular outflow tract obstruction. There were 3 early deaths from low cardiac output, in patients with significant associated lesions (severe neonatal Ebstein's, pulmonary artery-intact ventricular septum, biventricular conversion from Norwood stage 1). Two patients required early reintervention: 1 for balloon dilatation for stenosis and 1 for reoperation for paravalvular leak. During follow-up, 2 patients had mitral valve replacement with a 16-mm mechanical valve at 9 and 20 months from the cylinder valve implantation. The remaining 2 patients are alive and well 2 years and 2 months after the procedure.

CONCLUSIONS

Cylinder valve replacement of atrioventricular valves was feasible without any technical issues. It was successful in getting out of a difficult situation and allows for somatic growth and implantation of a reasonably-sized mechanical prosthesis on the annulus.

Pediatric Mitral Regurgitation: Standardized Repair-Oriented Strategy With Leaflet Plication

To introduce a standardized strategy and reproducible procedures of mitral repair for mitral regurgitation in the pediatric population with leaflet plication as a principal technique. Consecutive patients who had undergone mitral repair by our standardized repair-oriented strategy in our institution from January 2016 to December 2019 were included retrospectively. The standardized repair strategy included 3-step inspections and repair from the subvalvular to leaflet, and then to the annular level. The main surgical techniques included chordae detachment, papillary muscle splitting, leaflet plication, and posterior annuloplasty. The indication for leaflet plication was that the distance between 2 adjacent chordae tendineae was greater than 4 mm. A total of 113 patients were enrolled. During 22.6-month (range, 2-50 months) follow-up period, primary endpoint was documented in 15 (13.3%) patients, including 1 (0.9%) death, 0 transplantation, and 14 (12.4%) functional mitral failure. Freedom form primary endpoints at 6 months, 1 year, and 3 years was 94.7%, 94.7%, and 82.3%, respectively. Significant independent predictors of functional mitral valve failure were younger age (hazard ratio [HR], 0.28; 95% confidence interval [CI], 0.04-0.72; P = 0.037) and ischemic mitral regurgitation (MR) (HR, 24.34; 95% CI, 4.52-47.33; P < 0.001). Leaflet plication was significantly associated with well-functioned mitral valve (HR, 7.42; 95% CI, 2.35-30.54; P = 0.004). Compared with nonischemic MR group, ischemic MR group was noted with higher occurrence of primary endpoint events (11/28 vs 4/85, P < 0.001). The short- to mid-term outcomes of standardized mitral repair technique with leaflet plication were favorable, among which, however, repair for mitral regurgitation with ischemic lesions is comparatively challenging.

Double-Orifice Left Atrioventricular Valve: The Case for Preoperative Three-Dimensional Echocardiography

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Double-orifice left AV valve complicates successful repair of common AV canal.

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Two-dimensional imaging may not recognize or define double-orifice left AV valve.

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Three-dimensional echocardiography is useful for visualizing these complex valves.

Mitral Valve Surgery in Neonates, Infants, and Children: Surgical Approach, Outcomes, and Predictors

The surgical treatment of mitral disease in pediatrics is challenging. Managing diversity in patient anatomy, growth, and the need for long-term anticoagulation requires trade-offs between imperfect solutions. We sought to assess our approach to pediatric mitral valve surgery and identify predictors associated with mortality and recurrent mitral disease. The medical records, echocardiograms, and operative reports of all patients who underwent surgical intervention on the mitral valve from January 2000 to April 2016 were reviewed. A total of 143 patients underwent mitral valve surgery, 64 of which were neonates or infants (ages 10-355 days) and 79 of which were children (ages 1-17.8 years). Neonates and infants had a higher preoperative New York Heart Association heart failure classification in comparison to children (P < 0.001) with a less severe degree of mitral valve insufficiency (P = 0.007). Postoperative outcomes for primary repair patients (n = 133) demonstrated significant differences in recurrence of mitral valve disease, with 38% of neonates/infants and 21% of children affected (P = 0.028). Five-year rates of mortality or transplant were 22% (8%, 33%) in neonates and infants compared to 4% (0%, 10%) in children, P = 0.013. Mitral valve surgery in neonates and infants is particularly high risk and is associated with higher rate of recurrence and reintervention early. However, if successful early, mitral valve repair in neonates and infants can result in a durable freedom from reintervention that parallels freedom from reintervention in older children undergoing repair. Further understanding of mechanisms of failure and better matching of anatomic substrate to strategy is needed.

Outcome for Conservative Surgery for the Correction of Severe Mitral Valve Regurgitation in Children: A Single-Center Experience

Evolving reconstructive techniques have progressively become the preferred approach for treatment of pediatric mitral valve regurgitation. We present our experience in a cohort of patients undergoing surgical correction for severe mitral regurgitation. Fifty-five patients (age 1 month-18 years; median 5 years) were included in the present analysis. Different surgical techniques were used (posterior leaflet augmentation in 25, isolated cleft closure in 12, Alfieri-type procedure in 10, annuloplasty in 5, with artificial chordae in 2, and quadrangular resection with chordal transposition in 1). Follow-up time ranged from 1 to 192 months (median 38[IQR 12-54] months). Operative and follow-up mortality was 0%. Reintervention in the whole population occurred in 31% of patients. However, when first surgery was performed under 2 years of age (no = 17), reintervention reached nearly 50%. The degree of residual mitral regurgitation at follow-up remained stable after surgery, while a significant increase in mean transmitral gradient was observed over time (paired t test = 0.03). In multivariable Cox-regression analysis, post-surgical transmitral gradient was the only independent predictor for reintervention (p = 0.017; HR 2.4; 95%CI 1.2-5.1), after correcting for differences in age at surgery, type of reintervention, mitral annulus dimension, and BSA at the first surgery. ROC curve demonstrated that a post-surgical transmitral mean gradient value > 5 mmHg, was predictive for reintervention (AUC = 0.89; Youden index = 0.44). Our study suggests that the use of conservative technique strategy achieves satisfactory functional results in infants and children with severe MR, although the rate of reoperation in younger patients remains substantial. Post-operative moderate mitral stenosis was the strongest predictor for reoperation.

Travel distance and regional access to cardiac valve surgery

OBJECTIVE

Evidence in other surgical subspecialties suggests patients traveling farther to undergo surgery have worse outcomes. We sought to determine the impact of travel distance and travel beyond closest center on outcomes after valve surgery.

METHODS

Patients who underwent valve surgery ±CABG with a Society of Thoracic Surgeons (STS) predicted risk and zip code were extracted from a statewide STS database (2011-016). Patients were stratified by those receiving care greater than or equal to 20 miles from the closest surgical center (Traveler) or at the closest center (Non-Traveler). Multivariate logistic regression assessed the effects of travel distance and traveler status on mortality and major morbidity adjusted for STS predicted risk, median income by zip code, and payer status.

RESULTS

Median travel distance for all patients (n = 4765) was 19 miles and after risk-adjustment increasing distance was associated with reduced operative mortality (odds ratio [OR], 0.94 [0.89-1.00], P = .049) with no impact on major morbidity. Travelers (445 patients, 9.3%) had lower median income, higher self-pay and reoperative status, but similar urgent/emergent status and STS risk as Non-Travelers. Travelers had lower operative mortality (1.6% vs 4.3%, P = .005) which remained statistically lower after risk-adjustment (OR, 0.32 [0.14-0.75], P = .009). This mortality difference was particularly pronounced in patients with postoperative complications (3.1% vs 7.9%, P = .005).

CONCLUSIONS

Contrary to other surgical subspecialties, farther travel distance and bypassing the nearest surgical center were associated with lower rates of operative mortality and failure to rescue. Either referral patterns or financials reasons may result in Travelers ending up at high performing centers that prevent escalation of complications.

Patient-Specific Approach to Mitral Valve Replacement in Infants Weighing 10 kilograms or less

Background:

Mitral valve replacement (MVR) is the only option for infants with severe mitral valve disease that is not reparable; however, previously reported outcomes are not always favorable. Our institution has followed a tailored approach to sizing and positioning of mechanical valve prostheses in infants requiring MVR in order to obtain optimal outcomes.

Methods:

Outcomes for 22 infants ≤10 kg who have undergone MVR in Sydney, Australia, from 1998 to 2016, were analyzed. Patients were at a mean age of 6.8 ± 4.1 months (range: 0.8-13.2 months) and a mean weight of 5.4 ± 1.8 kg at the time of MVR. Most patients (81.8%) had undergone at least one previous cardiac surgical procedure prior to MVR, and 36.4% had undergone two previous procedures. Several surgical techniques were used to implant mechanical bileaflet prostheses.

Results:

All patients received bileaflet mechanical prostheses, with 12 receiving mitral prostheses and 10 receiving inverted aortic prostheses. Surgical technique varied between patients with valves implanted intra-annularly (n = 6), supra-annularly (n = 11), or supra-annularly with a tilt (n = 5). After a mean follow-up period of 6.2 ± 4.4 years, the survival rate was 100%. Six (27.3%) patients underwent redo MVR a mean of 102.2 ± 10.7 months after initial MVR. Four (18.2%) patients required surgical reintervention for development of left ventricular outflow tract obstruction and three (13.6%) patients required permanent pacemaker placement during long-term follow-up.

Conclusions:

The tailored surgical strategy utilized for MVR in infants at our institution has resulted in reliable valve function and excellent survival. Although redo is inevitable due to somatic growth, the bileaflet mechanical prostheses used displayed appropriate durability.

Technical performance scores are predictors of midterm mortality and reinterventions following congenital mitral valve repair

OBJECTIVES

The Technical Performance Score (TPS) has been shown to be predictive of postoperative mortality, morbidities and reinterventions following various cardiac procedures in children. We hypothesized that TPS is also a predictor of mitral valve repair outcomes.

METHODS

A review of patients who underwent mitral valve repair from January 2000 to December 2013 was performed. Primary repair of complete atrioventricular defect was excluded. The scores were determined according to previously published criteria based on the need for reintervention and predischarge echocardiograms: Class 1 (no residua), Class 2 (minor residua) or Class 3 (pacemaker implantation, major residua or reintervention for major residua prior to discharge). Cox proportional hazard models and Kaplan-Meier estimator were used.

RESULTS

A total of 587 patients underwent mitral repair (median age 2.6 years). Median follow-up duration was 3 years. There were 125 (21.3%) post-discharge mitral reinterventions and freedom from reintervention was 85.2%, 78.2% and 69.4% at 1, 2 and 5 years, respectively. Both TPS Class 2 [hazard ratio (HR) 3.6, 95% confidence interval (CI) 1.4-10.0; P  = 0.02] and Class 3 (HR 8.7, 95% CI 3.0-25.1; P  < 0.001) were associated with post-discharge reinterventions. There were 31 late deaths/transplantations, and transplant-free survival at 1, 2 and 5 years was 97.8%, 95.3% and 93.2%. TPS 3 was associated with decreased post-discharge transplant-free survival (HR 5.5, 95% CI 1.2-25.0; P  = 0.03). Post-discharge mitral reintervention was not associated with increased mortality.

CONCLUSIONS

The TPS is a strong predictor of midterm mortality and post-discharge mitral reintervention in congenital patients who underwent mitral repair.

Comparison of 3D Echocardiogram-Derived 3D Printed Valve Models to Molded Models for Simulated Repair of Pediatric Atrioventricular Valves

Mastering the technical skills required to perform pediatric cardiac valve surgery is challenging in part due to limited opportunity for practice. Transformation of 3D echocardiographic (echo) images of congenitally abnormal heart valves to realistic physical models could allow patient-specific simulation of surgical valve repair. We compared materials, processes, and costs for 3D printing and molding of patient-specific models for visualization and surgical simulation of congenitally abnormal heart valves. Pediatric atrioventricular valves (mitral, tricuspid, and common atrioventricular valve) were modeled from transthoracic 3D echo images using semi-automated methods implemented as custom modules in 3D Slicer. Valve models were then both 3D printed in soft materials and molded in silicone using 3D printed "negative" molds. Using pre-defined assessment criteria, valve models were evaluated by congenital cardiac surgeons to determine suitability for simulation. Surgeon assessment indicated that the molded valves had superior material properties for the purposes of simulation compared to directly printed valves (p < 0.01). Patient-specific, 3D echo-derived molded valves are a step toward realistic simulation of complex valve repairs but require more time and labor to create than directly printed models. Patient-specific simulation of valve repair in children using such models may be useful for surgical training and simulation of complex congenital cases.

Three-Dimensional Mitral Valve Morphology and Age-Related Trends in Children and Young Adults with Structurally Normal Hearts Using Transthoracic Echocardiography

BACKGROUND

The mitral valve has a complex three-dimensional (3D) morphology that is incompletely described by two-dimensional echocardiography (echo). Three-dimensional echo provides a more robust tool to analyze the mitral valve. The shape of the mitral annulus and leaflets, and differences with age, have not been described by 3D echo in normal children. Our objective was to characterize and quantify the 3D mitral valve morphology in children with normal transthoracic echocardiograms over a broad spectrum of age and to identify differences in valve shape with age.

METHODS

Three-dimensional midsystolic mitral valve models were constructed in 100 children and young adults with normal echocardiograms using 3D transthoracic images. Annular and leaflet metrics were quantified and regression equations were prepared. Interuser and intrauser variability was measured.

RESULTS

Two hundred fifty patients, from neonate to young adult, were retrospectively reviewed to obtain 100 evaluable patients (40% evaluable). The annular height to commissural width ratio of the mitral valve ("saddle shape") was preserved across age (median 24.3, IQR 21.8-28.1). Three-dimensional mitral valve area, length, and volume parameters were linearly related to body surface area (P < .001). The ratio of anterior to posterior leaflet length and posterior leaflet angle increased with body surface area (P = .0004 and .002, respectively) suggesting posterior movement of the coaptation line. Two-dimensional lateral annular diameter underestimated 3D lateral annular metrics (P < .001, mean difference 20-22%) but was highly correlated (R > 0.87, P < .001). Interuser and intrauser variability were acceptable.

CONCLUSIONS

Assessment of 3D mitral valve morphology in children is possible in a modern clinical pediatric echocardiography laboratory using transthoracic images, although further optimization of imaging is needed. The saddle shape of the mitral annulus was preserved across age and size. Most mitral valve parameters increased linearly with patient size. Further investigation is warranted to explore changes in valve morphology in the pediatric population in health and with disease.

Patient-specific pediatric silicone heart valve models based on 3D ultrasound

PURPOSE

Patient-specific heart and valve models have shown promise as training and planning tools for heart surgery, but physically realistic valve models remain elusive. Available proprietary, simulation-focused heart valve models are generic adult mitral valves and do not allow for patient-specific modeling as may be needed for rare diseases such as congenitally abnormal valves. We propose creating silicone valve models from a 3D-printed plastic mold as a solution that can be adapted to any individual patient and heart valve at a fraction of the cost of direct 3D-printing using soft materials.

METHODS

Leaflets of a pediatric mitral valve, a tricuspid valve in a patient with hypoplastic left heart syndrome, and a complete atrioventricular canal valve were segmented from ultrasound images. A custom software was developed to automatically generate molds for each valve based on the segmentation. These molds were 3D-printed and used to make silicone valve models. The models were designed with cylindrical rims of different sizes surrounding the leaflets, to show the outline of the valve and add rigidity. Pediatric cardiac surgeons practiced suturing on the models and evaluated them for use as surgical planning and training tools.

RESULTS

Five out of six surgeons reported that the valve models would be very useful as training tools for cardiac surgery. In this first iteration of valve models, leaflets were felt to be unrealistically thick or stiff compared to real pediatric leaflets. A thin tube rim was preferred for valve flexibility.

CONCLUSION

The valve models were well received and considered to be valuable and accessible tools for heart valve surgery training. Further improvements will be made based on surgeons' feedback.

Neonatal Mitral Valve Repair in Biventricular Repair, Single Ventricle Palliation, and Secondary Left Ventricular Recruitment: Indications, Techniques, and Mid-Term Outcomes

Objectives

Although mitral valve repair is rarely required in neonates, this population is considered to be at high risk for adverse outcomes. The aim of this study was to review the indications for surgery, mechanisms, repair techniques, and mid-term outcomes of neonatal mitral valve repair.

Methods

The demographic, procedural, and outcome data were obtained for all neonates who underwent mitral valve repair from 2005 to 2012. The primary endpoints included mortality, transplantation, and mitral valve reoperation.

Results

Twenty patients were included during the study period. Median age at operation was 11 days (range: 3–25). Eleven patients (55%) presented with mitral stenosis, three had regurgitation (15%), and six had mixed mitral disease (30%). Nineteen of 20 patients had mild or less regurgitation on immediate postoperative imaging. During a median follow-up of 5 months (1 month–4.8 years), six patients died at a median of 33 months (7–41 months) from repair and one patient required orthotopic heart transplantation. Six patients required mitral valve reoperation, five for mitral valve re-repair, and one for mitral valve replacement. Freedom from death, transplantation, or mitral valve replacement was 84.2 ± 8.4% at 1 month, 71.3 ± 11% at 6 months, 64.1 ± 12% at 1 year, and 51.3 ± 15% at 2 years and was worse for patients presenting with mitral regurgitation compared to stenosis or mixed mitral valve disease.

Conclusion

Although mitral valve repair can be performed with acceptable immediate postoperative result, this procedure carries a high burden of late death and mitral valve reoperations.

Valve reconstruction for congenital mitral valve disease

The surgical treatment of mitral valve disease in children is a challenging problem. Mitral stenosis and regurgitation may occur in isolation or together. Mitral valve repair is almost always preferable to replacement. Mitral valve replacement is not an ideal alternative to repair due to limitations of size, growth, structural valve degeneration, anticoagulation and poor survival. Surgical repair of congenital mitral stenosis must address the multiple levels of obstruction, including resection of the supramitral ring, thinning of leaflets and mobilization of the subvalvular apparatus. Sometimes leaflet augmentation is required. Repair of mitral regurgitation in children may involve simple cleft closures, edge-to-edge repairs, triangular resections and annuloplasties. Techniques used in adults, such as annuloplasty bands or artificial chords, may not be appropriate for children. Overall, an imperfect mitral valve repair may be more acceptable than the negative consequences of a replacement in a child.

Biventricular repair for common atrioventricular canal defect with parachute left atrioventricular valve

OBJECTIVES

Parachute left atrioventricular (AV) valve can complicate repair of common atrioventricular canal (CAVC), and single-ventricle palliation is sometimes preferred. The goal of this study is to review our single institutional experience in biventricular repair in this patient group.

METHODS

The demographic, procedural and outcome data were obtained for all children who underwent biventricular repair for complete CAVC with parachute [single left ventricular (LV) papillary muscle] or forme fruste parachute left AV valve (closely spaced LV papillary muscles) from 2001 to 2012. Primary outcomes were survival, freedom from left AV valve stenosis (defined as an inflow gradient ≥7 mmHg and post-capillary pulmonary hypertension) and freedom from left AV valve replacement.

RESULTS

A total of 24 patients were included (21 parachutes, 3 forme frustes). There was 1 early death (4.2%). At discharge, no patient had more-than-mild regurgitation and 1 had stenosis. During a median follow-up of 3.7 years (IQR 4 months to 5 years), there were 2 late deaths (8.3%), 6 patients (25%) presented significant left AV valve stenosis and 2 patients (8.3%) required valve replacement. Freedom from stenosis was 95 ± 4.9% at 1 year, 83.1 ± 8.9% at 3 years, 64.7 ± 13.5% at 5 years and 51.7 ± 15.8% at 10 years. Complete cleft closure was not associated with a significantly different freedom from left AV valve reoperation (log-rank test, P = 0.89) or significant stenosis (P = 0.47).

CONCLUSION

Biventricular repair in parachute left AV valve and CAVC is feasible with acceptable mortality and freedom from stenosis. The burden of reoperation remains significant in this patient group.

Biodegradable materials for surgical management of infective endocarditis: new solution or a dead end street?

Background

One third of patients with infective endocarditis will require operative intervention. Given the superiority of valve repair over valve replacement in many indications other than endocarditis, there has been increasing interest and an increasing number of reports of excellent results of valve repair in acute infective endocarditis. The theoretically ideal material for valve repair in this setting is non-permanent, “vanishing” material, not at risk of seeding or colonization. The goal of this contribution is to review currently available data on biodegradable materials for valve repair in infective endocarditis.

Discussion

Rigorous electronic and manual literature searches were conducted to identify reports of biodegradable materials for valve repair in infective endocarditis. Articles were identified in electronic database searches of Medline, Embase and the Cochrane Library, using a predetermined search strategy. 49 manuscripts were included in the review. Prosthetic materials needed for valve repair can be summarized into annuloplasty rings to remodel the mitral or tricuspid annulus, and patch materials to replace resected valvar tissue. The commercially available biodegradable annuloplasty ring has shown interesting clinical results in a single-center experience; however further data is required for validation and longer follow-up. Unmodified extra-cellular matrix patches, such as small intestinal submucosa, have had promising initial experimental and clinical results in non-infected valve repair, although in valve repair for endocarditis has been reported in only one patient, and concerns have been raised regarding their mechanical stability in an infected field.

Summary

These evolving biodegradable devices offer the potential for valve repair with degradable materials replaced with autologous tissue, which could further improve the results of valve repair for infective endocarditis. This is an evolving field with promising experimental or initial clinical results, however long-term outcomes are lacking and further data is necessary to validate this theoretically interesting approach to infective endocarditis.