Results after mitral valve replacement with mechanical prostheses in young children

Mitral valve repair using leaflet expansion and subpartial annuloplasty in children

Objective

Mitral valve reconstruction in the pediatric population is a challenge due to the frequent combination of annular dilatation and leaflet restriction and the need for growth. We present a novel strategy using leaflet expansion and subpartial annuloplasty with polytetrafluoroethylene reinforcement.

Methods

From January 2014 through May 2021, 11 children aged 5 months to 14 years (median, 24 months) underwent elective mitral valve repair due to severe mitral valve regurgitation. The mitral valve abnormalities included congenital malformations (n = 7), postoperative leakage following commissurotomy (n = 1), and functional mitral valve regurgitation due to dilated cardiomyopathy (n = 3). Surgery consisted of leaflet expansions with autologous, untreated pericardium and subpartial annuloplasty with polytetrafluoroethylene reinforcement.

Results

All children survived their surgeries with uneventful postoperative courses, except for 1 patient who needed an early reoperation to resolve a functional stenosis due to a spinnaker phenomenon. At discharge, mean gradient was 3.5 ± 3.9 mm Hg, with trivial mitral regurgitation in 9 patients (82%). All patients were alive and asymptomatic during the median follow-up of 3 years (range, 1-7 years). Their echocardiographic data showed a mean transmitral gradient of 4.4 ± 1.7 mm Hg and remained unchanged. Residual mitral valve regurgitation was trivial or mild in 9 patients (82%) and moderate in 2 patients (18%).

Conclusions

Leaflet expansion with autologous pericardium and subpartial annuloplasty with polytetrafluoroethylene reinforcement for mitral regurgitation in the pediatric population gives stable and satisfactory results both early and at intermediate follow-up, permitting growth of the mitral valve.

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.

Predictors of permanent pacemaker insertion after mitral valve replacement: a systematic review

OBJECTIVE

As the established surgical mitral valve replacement (MVR) expands towards various contemporary techniques and access routes, the predictors and burden of procedure-related complications including the need for permanent pacemaker (PPM) implantation need to be identified.

METHODS

Digital databases were searched systematically to identify studies reporting the incidence of PPM implantation after MVR. Detailed study and patient-level baseline characteristics including the type of study, sample size, follow-up, number of post-MVR PPM implantations, age, gender, and baseline ECG abnormalities were abstracted.

RESULTS

A total of 12 studies, recruiting 37,124 patients were included in the final analysis. Overall, 2,820 (7.6%) patients required a PPM with the net rate ranging from 1.7% to 10.96%. Post-MVR atrioventricular (AV) block was the most commonly observed indication for PPM, followed by sinoatrial (SA) node dysfunction, and bradycardia. Age, male gender, pre-existing comorbid conditions, prior CABG, history of arrhythmias or using anti-arrhythmic drugs, AF ablation, and double valve replacement were predictors of PPM implantation post-MVR.

CONCLUSION

Age, male gender, comorbid conditions like diabetes and renal impairment, prior CABG, double valve replacement, and anti-arrhythmic drugs served as positive predictors of PPM implantation in patients undergoing MVR. This article is protected by copyright. All rights reserved.

Transcatheter Mitral Valve-in-Valve Implantation in Pediatric Patients

Background

Methods

Results

Conclusions

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.

Echocardiographic changes in patients with a cylinder mitral valve replacement: Preliminary analysis

AIMS

Cylinder mitral valve construct (cMVC) is new technique for replacing the mitral valve compared to more traditional mitral valve replacement (MVR) procedures. Goal of this study was to describe echocardiographic changes over time in patients undergoing a cMVC. Secondary goal was to compare echocardiographic changes in patients that underwent a cMVC to a group of patients that underwent a MVR.

METHODS

Retrospective analysis of patients undergoing a cMVC was performed. Demographics, discharge echocardiogram, and recent echocardiogram vales were evaluated. Age matched patients undergoing a MVR were assessed. Discharge and recent echocardiographic parameters were compared within the cMVC group. cMVC and MVR values were compared between groups.

RESULTS

Five cMVC patients were studied. Age at surgery for the cMVC was 4.3 ± 4.2 years (median 2.2, .8-10.3 years). Time interval from hospital discharge echocardiogram to the most recent echocardiogram was 1.2 ± .7 years (median 1.0, .6-2.0 years). Mean mitral valve gradient significantly increased over time (3.6 ± 3.0 mm Hg vs 7.6 ± 2.9 mm Hg). There were significant improvements in left ventricular diameters, systolic sphericity index, shortening fraction, and ejection fraction over time. There were no significant differences in demographics, discharge echocardiogram values, and follow up echocardiogram values between the cMVC and MVR groups.

CONCLUSION

In conclusion, echocardiographic indices of left ventricular function improved over time in patients undergoing cMVC. In addition, there were no significant differences between cMVC and MVR patients in echocardiographic values. Studies with a larger patient sample with longer follow up are needed to determine if cMVC continues to have comparable echocardiographic results to MVR.

What Factors Should Be Considered to Improve Outcome of Mechanical Mitral Valve Replacement in Children?

OBJECTIVE

To identify risk factors for pediatric mechanical mitral valve replacement (mMVR) to improve management in this challenging population.

METHODS

From 1993 to 2019, 93 children underwent 119 mMVR operations (median age, 8.8 years [interquartile range [IQR]: 2.1-13.3], 54.6% females) at our institution. Twenty-six (21.8%) patients underwent mMVR at ≤2 years and 93 (78.2%) patients underwent mMVR at >2 years. Median follow-up duration was 7.6 years [IQR: 3.2-12.4].

RESULTS

Early mortality was 9.7%, but decreased with time and was 0% in the most recent era (13.9% from 1993 to 2000, 7.3% from 2001 to 2010, 0% from 2011 to 2019, P = .04). It was higher in patients ≤2 years compared to patients >2 years (26.9% vs 2.2%, P < .01). On multivariable analysis for mitral valve reoperation, valve size <23 mm was significant with a hazard ratio of 5.38 (4.87-19.47, P = .01);. Perioperative stroke occurred in 1% and permanent pacemaker was necessary in 12%. Freedom from mitral valve reoperation was higher in patients >2 years and those with a prosthesis ≥23 mm. Median time to reoperation was 7 years (IQR: 4.5-9.1) in patients >2 years and 3.5 years (IQR: 0.6-7.1) in patients ≤2 years (P = .0511), but was similar between prosthesis sizes (P = .6). During follow-up period (median 7.6 years [IQR: 3.2-12.4], stroke occurred in 10%, prosthetic valve thrombosis requiring reoperation in 4%, endocarditis in 3%, and bleeding in 1%.

CONCLUSION

Early and late outcomes of mMVR in children are improved when performed at age >2 years and with prosthesis size ≥23 mm. These factors should be considered in the timing of mMVR.

Long-term outcomes of mitral valve replacement in patients weighing less than 10 kg

Background

The outcomes of mitral valve replacement (MVR) in pediatrics especially in the patients weighing less than 10 kg are not always favorable. This study aimed to measure long-term outcomes of MVR in our institution.

Methods

Nine young children weighing less than 10 kg underwent MVR with mechanical prostheses were enrolled in this retrospectively study. Kaplan–Meier survival analysis was used for the prediction of freedom from death and adverse events. Chi-square test was performed to compare outcomes for patients with different ratios of mechanical prosthesis size and body weight. Fourteen related literatures were also reviewed to support our study.

Results

All patients received bileaflet mechanical prostheses replacement. The surgical technique varied among the patients with prostheses implanted in the intra-annular (n = 5), supra-annular (n = 1), or with a Dacron conduit segment in the supra-annular position (n = 3). The valve size/weight ratio ranged from 2.11 to 5.00. There were two early death and one late death post-operation. The mean follow-up period was 80.67 ± 63.37 months, the transvalvular gradient was 10.5 ± 1.76 mmHg (range 8 to 12) and the peak gradient of LVOT was 5.00 ± 0.64 mmHg. One (11.1%) patient underwent an immediate revision MVR after initial MVR due to the periprosthetic leak. No patients required surgical reintervention or permanent pacemaker placement during long-term follow-up.

Conclusions

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

Supplementary Information

The online version contains supplementary material available at 10.1186/s13019-021-01443-9.

Replacement of the Mitral Valve Under One Year of Age: Size Matters

Surgical management of mitral valve disease in neonates and infants is challenging. When repair is no longer feasible, replacement may become inevitable, but should only be considered as an option of last resort due to the remarkably high rate of associated morbidity and mortality. Mechanical valves are the preferred choice in large annuli, while stented conduits seem promising in smaller ones. In patients with a preoperative mitral valve annulus equal or larger than 15-16 mm, an intra-annular placement of the smallest mechanical valve available should be attempted. In patients with smaller annuli, the placement of a stented valved conduit seems to display a lower mortality risk. Supra-annular implantation of prostheses should be reserved for exceptional cases and to those familiar with this technique because of the high rate of associated complications.

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.

Mitral Valve Replacement in Pediatrics Using an Extracellular Matrix Cylinder Valve: A Case Series

Mitral valve replacement (MVR) in children under 2 years is associated with significant morbidity and mortality. Decellularized porcine intestinal submucosa is a commercially available formulation of an extracellular matrix (ECM) with an indication for cardiac tissue repair. The present study reports our experience using ECM cylinder valves in patients for MVR. A retrospective review of patients under 2 years who underwent ECM custom-made cylinder mitral valve (ECM-MV) replacement was performed. Clinical, demographic, operative and post-operative follow-up data, including serial echocardiographic data are presented. Eight patients (age 5.6 ± 1.6 months; weight: 6.0 ± 1.1 kg) were identified who underwent ECM-MVR. There was one in-hospital death and no major neurological events. Six patients underwent replacement of their cylinder valve with either a Melody valve inside the ECM-MVR (n = 3), a mechanical valve (n = 2), or a decellularized bovine pericardial cylinder valve (n = 1). The mean time to replacement surgery was 8.4 ± 2.6 months after ECM-MV. The indications for replacement of ECM-MV included mitral stenosis/regurgitation (n = 4) or dehiscence (n = 2). One remaining patient is 24 months from ECM-MV, with trivial regurgitation and no stenosis. Mitral valve creation using ECM is an option for MVR in pediatrics, avoiding anticoagulation, and provides a suitable construct for later placement of a Melody valve, extending surgical and non-surgical options. However, the durability of the native ECM-MV in the mitral position is concerning considering the high re-intervention rate in a relatively short time period. Further studies are needed to determine the longer-term outcomes of this valve in this complex patient population.

Mechanical Mitral Valve Replacement: A Multicenter Study of Outcomes With Use of 15- to 17-mm Prostheses

BACKGROUND

The aim of this study was to evaluate early and mid-term outcomes (mortality and prosthetic valve reintervention) after mitral valve replacement with 15- to 17-mm mechanical prostheses.

METHODS

A multicenter, retrospective cohort study was performed among patients who underwent mitral valve replacement with a 15- to 17-mm mechanical prosthesis at 6 congenital cardiac centers: 5 in The Netherlands and 1 in the United States. Baseline, operative, and follow-up data were evaluated.

RESULTS

Mitral valve replacement was performed in 61 infants (15 mm, n = 17 [28%]; 16 mm, n = 18 [29%]; 17 mm, n = 26 [43%]), of whom 27 (47%) were admitted to the intensive care unit before surgery and 22 (39%) required ventilator support. Median age at surgery was 5.9 months (interquartile range [IQR] 3.2-17.4), and median weight was 5.7 kg (IQR, 4.5-8.8). There were 13 in-hospital deaths (21%) and 8 late deaths (17%, among 48 hospital survivors). Major adverse events occurred in 34 (56%). Median follow-up was 4.0 years (IQR, 0.4-12.5) First prosthetic valve replacement (n = 27 [44%]) occurred at a median of 3.7 years (IQR, 1.9-6.8). Prosthetic valve endocarditis was not reported, and there was no mortality related to prosthesis replacement. Other reinterventions included permanent pacemaker implantation (n = 9 [15%]), subaortic stenosis resection (n = 4 [7%]), aortic valve repair (n = 3 [5%], and aortic valve replacement (n = 6 [10%]).

CONCLUSIONS

Mitral valve replacement with 15- to 17-mm mechanical prostheses is an important alternative to save critically ill neonates and infants in whom the mitral valve cannot be repaired. Prosthesis replacement for outgrowth can be carried out with low risk.

Revisiting prosthesis choice in mitral valve replacement in children: Durable alternatives to traditional bioprostheses

OBJECTIVE

To determine risk factors for re-replacement and death or transplant following mitral valve replacement (MVR) in children METHODS: This is a retrospective 26-year review of patients younger than 20 years of age undergoing MVR between 1992 and 2018 at single institution. Outcomes included freedom from re-MVR and transplant-free survival. Cox proportional hazards regression models assessed association between outcomes and potential risk factors.

RESULTS

At median age 4.2 years, 190 children underwent 290 MVR: 180 mechanical, 63 porcine, 13 pericardial, and 34 stented bovine jugular vein valves. Re-MVR occurred in 100 valves. Freedom from re-MVR at 5 and 10 years was 76% and 44%. Times to re-MVR were associated with prosthesis type (P < .001), with porcine and pericardial valves at greatest risk. Other risk factors for prosthetic failure included smaller prosthesis size and left ventricular hypoplasia. There were 9 transplants and 44 deaths. Transplant-free survival at 5 and 10 years was 81% and 76%. Prosthesis type was significantly associated with time to death/transplant in univariate analysis only (P = .021), with porcine at greater risk than mechanical. Independent risk factors for death/transplant included larger indexed geometric orifice area and longer bypass time.

CONCLUSIONS

In pediatric patients undergoing MVR, mechanical and stented bovine jugular vein valves were associated with increased durability compared with fixed-diameter bioprosthetic alternatives.

Three-Dimensional Modeling of Surgically Implanted Stent-Based Valves in the Mitral Position in Children

PURPOSE

In children with a mitral annulus too small to accommodate traditional prostheses, surgical implantation of stent-based valves is a promising option. However no reliable preoperative methods exist to guide patient selection, device sizing, and positioning. We describe a novel methodology to visualize and quantify device fit in 3-dimensional echocardiogram (3DE)-derived heart models.

DESCRIPTION

Heart models were created from existing preoperative 3DEs using custom software. Valve models were virtually implanted into the models, and both device fit and left ventricular outflow tract (LVOT) area were quantified.

EVALUATION

The 3DEs of 3 patients who underwent Melody valve placement in the mitral position were retrospectively modeled: 1 with LVOT obstruction, 1 with perivalvar leak, and 1 without complications. In all cases 2-dimensional measurements underestimated 3D annular dimensions, and the patient with clinical LVOT obstruction had the lowest predicted LVOT area-to-aortic area ratio (0.5).

CONCLUSIONS

3DE-based preoperative modeling of surgical implantation of stent-based valves in the mitral position may improve quantification of mitral valve dimensions and inform risk stratification for potential LVOT obstruction.

Interannular Bridge: A Novel Approach to Address Congenital Mitral Regurgitation

A male infant with Kabuki syndrome had trivial congenital mitral regurgitation diagnosed at birth. At the age of 2 years and 9 months, the regurgitation worsened from mild to severe; thus, expedited surgical treatment was pursued. The primary operative finding was severe dysplastic two-leaflet disease. After completing chordal replacement as a conventional repair procedure, more-than-moderate central regurgitation caused by establishing a shallow coaptation between the anterior and posterior leaflets persisted. We report a successful case of mitral valve repair involving the novel option of interannular bridge for valvuloplasty to address congenital mitral regurgitation.

Outcomes of Supra-annular Mechanical Atrioventricular Valve Replacement with Polytetrafluoroethylene Graft in Infants and Children

Despite improvements in valve repair techniques, conditions in which infants and children need for mechanical valve replacement (MVR) are still present. We analyzed supra-annular MVR outcomes in infants and children with small annulus and compared them with conventional annular MVR outcomes. Data were collected retrospectively from medical records of infants and children (weighing < 20 kg) who underwent atrioventricular valve replacement with mechanical valve in Seoul National University Children's Hospital between December 1984 and January 2019. We identified 8 patients (median age 20 months, median weight 10.2 kg) who underwent supra-annular MVR with polytetrafluoroethylene graft (supra-annular group). The patients were diagnosed with congenital mitral valve malformation (5 patients), complete atrioventricular septal defect (2 patients), and functional single ventricle (1 patient). The implanted mechanical valve size ranged from 16 to 23 mm. Thirty-three patients (median age 40 months, median weight 13 kg) underwent conventional annular MVR (annular group). The survival rate was not significantly different between the supra-annular and annular groups (75.0 vs 78.8%, P = 0.816). In patients with biventricular repair (7 patients with supra-annular MVR and 28 patients with annular MVR), mechanical valve-to-mitral valve annulus size ratio was higher in the supra-annular group than in the annular group (1.24 ± 0.30 vs 0.96 ± 0.22, P = 0.035). No coronary complication or heart block were observed in the supra-annular group. Supra-annular MVR with polytetrafluoroethylene graft may be a feasible surgical option in children with a small annulus when valve repair is unsuccessful.

Outcomes of mitral valve replacement with bileaflet mechanical prosthetic valve in children

OBJECTIVES

We examined the outcomes following mitral valve replacement with bileaflet mechanical prosthetic valve in children and identified the predictors for mortality and reoperation.

METHODS

Medical records from 49 children who underwent mitral valve replacement between 1982 and 2015 were reviewed retrospectively. Median age and body weight at initial mitral valve replacement were 2.4 years and 9.7 kg, respectively. The median follow-up was 13 years. Surgical results and predictors for mortality and reoperation were investigated.

RESULTS

There was no operative mortality; eight late deaths occurred. The actuarial survival rates were 89.5%, 84.2%, and 80.7% at 5, 10, and 15 years, respectively, after initial mitral valve replacement. The actuarial freedom rates from related complications were 89.5%, 78.3%, and 70.7% at 5, 10, and 15 years, respectively. Nineteen patients required 1st re-mitral valve replacement at a median of 5.9 years; six of these 19 required 2nd re-mitral valve replacement at a median of 8.9 years after 1st re-MVR. The actuarial freedom rates from re-mitral valve replacement were 86.0%, 56.8%, and 44.2% at 5, 10, and 15 years, respectively. No predictor for death was determined; however, the predictor for re-mitral valve replacement was initial valve diameter less than 19 mm.

CONCLUSIONS

Survival outcomes among children after mitral valve replacement with bileaflet mechanical prosthetic valve in biventricular heart were satisfactory. However, complications, including re-mitral valve replacement, were frequent and the predictor was of a small prosthesis size.

Surgical Atrioventricular Valve Replacement With Melody Valve in Infants and Children

Background Pediatric patients with atrioventricular valve disease have limited options for prosthetic valve replacement in sizes <15 mm. Based on successful experience with the stented bovine jugular vein graft (Melody valve) in the right ventricular outflow tract, the prosthesis has been modified for surgical valve replacement in pediatric patients with atrioventricular dysfunction with the intention of subsequent valve expansion in the catheterization laboratory as the child grows. Methods and Results A multicenter, retrospective cohort study was performed among patients who underwent atrioventricular valve replacement with Melody valve at 17 participating sites from North America and Europe, including 68 patients with either mitral (n=59) or tricuspid (n=9) replacement at a median age of 8 months (range, 3 days to 13 years). The median size at implantation was 14 mm (range, 9-24 mm). Immediately postoperatively, the valve was competent with low gradients in all patients. Fifteen patients died; 3 patients underwent transplantation. Nineteen patients required reoperation for adverse outcomes, including valve explantation (n=16), left ventricular outflow tract obstruction (n=1), permanent pacemaker implantation (n=1), and paravalvular leak repair (n=1). Twenty-five patients underwent 41 episodes of catheter-based balloon expansion, exhibiting a significant decrease in median gradient ( P<0.001) with no significant increase in grade of regurgitation. Twelve months after implantation, cumulative incidence analysis indicated that 55% of the patients would be expected to be free from death, heart transplantation, structural valve deterioration, or valve replacement. Conclusions The Melody valve is a feasible option for surgical atrioventricular valve replacement in patients with hypoplastic annuli. The prosthesis shows acceptable short-term function and is amenable to catheter-based enlargement as the child grows. However, patients remain at risk for mortality and structural valve deterioration, despite adequate early valvular function. Device design and implantation techniques must be refined to reduce complications and extend durability. Clinical Trial Registration URL: https://www.clinicaltrials.gov. Unique identifier: NCT02505074.

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.

Outcomes of Mechanical Mitral Valve Replacement in Children

BACKGROUND

Mitral valve anomalies in children are rare but frequently severe, recalcitrant, and not often amenable to primary repair, necessitating mechanical mitral valve replacement (M-MVR). This study examined outcomes of a cohort undergoing a first M-MVR at age younger than 21 years.

METHODS

We queried the Pediatric Cardiac Care Consortium, a multi-institutional United States-based cardiac intervention registry, for patients undergoing first M-MVR for 2-ventricle congenital heart disease. Survival and transplant status through 2014 were obtained from Pediatric Cardiac Care Consortium and linkage with the National Death Index and the Organ Procurement and Transplantation Network.

RESULTS

We identified 441 patients (median age, 4.3 years; interquartile range, 1.3 to 10.1 years) meeting study criteria. The commonest disease necessitating M-MVR was atrioventricular canal (44.3%). Early mortality (death <90 days after M-MVR) was 11.1%; there was increased risk of early death if age at M-MVR was younger than 2 years (odds ratio, 7.8; 95% confidence interval [CI], 1.1 to 56.6) and with concurrent other mechanical valve placement (odds ratio, 8.5; 95% CI, 2.0 to 35.6). In those surviving more than 90 days after M-MVR, transplant-free survival was 76% at 20 years of follow-up (median follow-up, 16.6 years; interquartile range, 11.9 to 21.3 years). Adjusted analysis in those who survived more than 90 days showed elevated risk of death/transplant for boys (hazard ratio, 1.5; 95% CI, 1.0 to 2.3), age at M-MVR younger than 2 years (10-year survival: hazard ratio, 4.3; 95% CI, 1.2 to 15.1), and nonbileaflet prosthesis placement (hazard ratio, 2.4; 95% CI, 1.3 to 4.3).

CONCLUSIONS

M-MVR is a viable strategy in children with unrepairable mitral valve disease. Age younger than 2 years at the first M-MVR is associated with significant early risk of death and poorer long-term survival.

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.

Echocardiographic assessment of prosthetic mitral valves in children

AIMS

We studied how Doppler-derived hemodynamic parameters in children change as the relative prosthetic mitral valve (PMV) size decreases with somatic growth and evaluated the diagnostic utility of the parameters for detecting PMV obstruction in children.

METHODS AND RESULTS

We reviewed 26 echocardiographic examination results of 15 mechanical bileaflet PMVs in 12 children. The median age at echocardiographic examination was 6.6 (0.6-18.1) years. The PMV functioned normally in 24 examinations but was obstructed due to thrombosis in two cases. PMV sizes ranged between 16 and 25 mm, which were standardized to body surface area (BSA) at the examination with z-score calculations. We assessed the peak E velocity, mean pressure gradient (PG), and pressure half time (PHT) of the transprosthetic flow, the velocity-time integral (VTI) ratio of the PMV inflow to the left ventricular outflow, and the BSA-indexed effective orifice area (iEOA) of the PMV calculated with the continuity equation. Linear regression analysis revealed statistically significant correlations between all parameters of normally functioning PMVs and the PMV size z-scores (Pearson correlation coefficients: peak E velocity, -0.68; mean PG, -0.71; PHT, -0.82; VTI ratio, -0.76; iEOA, 0.79). Compared with the predictive values derived from the regression equations, the VTI ratio and iEOA exceeded ± 2 standard errors in both patients with obstructive PMVs.

CONCLUSION

To assess PMV function in children, Doppler-derived hemodynamic parameters should be compared with their predictive values based on relative PMV sizes. The deviation of the VTI ratio and iEOA from their predictive values may indicate prosthetic obstruction.

Assessment of the Melody valve in the mitral position in young children by echocardiography

OBJECTIVES

Mitral valve replacement (MVR) in young children is limited by the lack of small prostheses. Our institution began performing MVR with modified, surgically placed, stented jugular vein grafts (Melody valve) in 2010. We sought to describe key echocardiographic features for pre- and postoperative assessment of this novel form of MVR.

METHODS

The pre- and postoperative echocardiograms of 24 patients who underwent Melody MVR were reviewed. In addition to standard measurements, preoperative potential measurements of the mitral annulus were performed whereby dimensions were estimated for Melody sizing. A ratio of the narrowest subaortic region in systole to the actual mitral valve dimension (SubA:MV) was assessed for risk of postoperative left ventricular outflow tract obstruction (LVOTO).

RESULTS

Melody MVR was performed at a median of 8.5 months (5.6 kg) for stenosis (5), regurgitation (3), and mixed disease (16). Preoperatively, actual mitral z scores measured hypoplastic (median -3.1 for the lateral [lat] dimension; -2.1 for the anteroposterior [AP] dimension). The potential measurements often had normal z scores with fair correlation with intraoperative Melody dilation (ρ = 0.51 and 0.50 for lat and AP dimensions, respectively, both P = .01). A preoperative SubA:MV <0.5 was associated with postoperative LVOTO, which occurred in 4 patients. Postoperatively, mitral gradients substantially improved, with low values relative to the effective orifice area of the Melody valve. No patients had significant regurgitation or perivalvar leak.

CONCLUSIONS

Preoperative echocardiographic measurements may help guide intraoperative sizing for Melody MVR and identify patients at risk for postoperative LVOTO. Acute postoperative hemodynamic results were favorable; however, ongoing assessment is warranted.

Supra-annular mitral valve implantation in very small children

OBJECTIVE

Mitral valve replacement (MVR) is a surgical option when mitral valvuloplasty is not feasible/successful. This study reviews our experience with MVR in very young children.

METHODS

From July 2004 to January 2014, seven children (mean age 13.3 ± 11.2 months; range 4 months to 35 months; mean body weight 6.0 ± 2.2 kg) underwent MVR with a mechanical prosthesis in the supra-annular position. To provide better exposure in the left atrium, we performed in all but one case a biatrial transeptal incision according to Guiraudon. Six patients had congenital defects of the mitral valve and one had rheumatic. Six patients had undergone previous cardiosurgical procedures.

RESULTS

All patients were implanted with a CarboMedics (CarboMedics, Austin, TX, USA) mechanical prosthesis. Mean prosthesis size was 19.0 ± 3.1 mm (range 16 to 25). There were no cases of operative or late mortality. At follow-up (mean 67.1 ± 34.8 months; range 25 to 108 months) two patients (28.6%) required reoperation both for thrombotic pannus formation over the disc at two and three months from first operation, respectively; only in one case was replacement necessary.

CONCLUSION

Supra-annular MVR may be considered a feasible secondary surgical option in children with a small annulus when mitral valvuloplasty is unsuccessful or unsuitable. Early and mid-term outcomes are acceptable but complications are not uncommon, especially related to thrombotic events.

Successful treatment of severe mechanical mitral valve thrombosis with tissue plasminogen activator in a 7-month-old infant

Severe thrombosis of a mechanical valve is a rare complication in pediatric patients. Thrombolytic therapy as treatment of mechanical mitral valve thrombosis has rarely been reported in young infants. We report the successful treatment with recombinant tissue-type plasminogen activator of a mechanical mitral valve thrombus in a 7 month-old patient with trisomy 21, complete atrioventricular canal defect and pulmonary hypertension status post complete atrioventricular canal repair and subsequent prosthetic mitral valve replacement. He presented with respiratory decompensation and shock secondary to severe mechanical mitral valve stenosis. Serial echocardiograms showed significant resolution of the thrombus within 18 h of infusion with no major bleeding complications during the treatment course. Although a rare complication of mechanical valve placement in pediatrics, thrombosis of mechanical valves may result in severe hemodynamic and respiratory compromise. This case demonstrates that thrombolytic therapy is a feasible option for the treatment of critical thrombosis in pediatric patients after MVR.

Review of mitral valve insufficiency: repair or replacement

Mitral valve (MV) dysfunction is the second-most common clinically significant form of valvular defect in adults. MV regurgitation occurs with the increasing frequency of degenerative changes of the aging process. Moreover, other causes of clinically significant MV regurgitation include cardiac ischemia, infective endocarditis and rhematic disease more frequently in less developed countries. Recent evidence suggests that the best outcomes after repair of severe degenerative mitral regurgitation (MR) are achieved in asymptomatic or minimally symptomatic patients, who are selected for surgery soon after diagnosis on the basis of echocardiography. This review will focus on the surgical management of mitral insufficiency according to its aetiology today and will give insight to some of the perspectives that lay in the future.

Valve replacement in children: a challenge for a whole life

Valvular pathology in infants and children poses numerous challenges to the paediatric cardiac surgeon. Without question, valvular repair is the goal of intervention because restoration of valvular anatomy and physiology using native tissue allows for growth and a potentially better long-term outcome. When reconstruction fails or is not feasible, valve replacement becomes inevitable. Which valve for which position is controversial. Homograft and bioprosthetic valves achieve superior haemodynamic results initially but at the cost of accelerated degeneration. Small patient size and the risk of thromboembolism limit the usefulness of mechanical valves, and somatic outgrowth is an universal problem with all available prostheses. The goal of this article is to address valve replacement options for all four valve positions within the paediatric population. We review current literature and our practice to support our preferences. To summarize, a multitude of opinions and surgical experiences exist. Today, the valve choices that seem without controversy are bioprosthetic replacement of the tricuspid valve and Ross or Ross-Konno procedures when necessary for the aortic valve. On the other hand, bioprostheses may be implanted when annular pulmonary diameter is adequate; if not or in case of right ventricular outflow tract discontinuity, it is better to use a pulmonary homograft with the Ross procedure. Otherwise, a valved conduit. Mitral valve replacement remains the most problematic; the mechanical prosthesis must be placed in the annular position, avoiding oversizing. Future advances with tissue-engineered heart valves for all positions and new anticoagulants may change the landscape for valve replacement in the paediatric population.

Antithrombotic therapy in neonates and children: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

Neonates and children differ from adults in physiology, pharmacologic responses to drugs, epidemiology, and long-term consequences of thrombosis. This guideline addresses optimal strategies for the management of thrombosis in neonates and children.

METHODS

The methods of this guideline follow those described in the Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines.

RESULTS

We suggest that where possible, pediatric hematologists with experience in thromboembolism manage pediatric patients with thromboembolism (Grade 2C). When this is not possible, we suggest a combination of a neonatologist/pediatrician and adult hematologist supported by consultation with an experienced pediatric hematologist (Grade 2C). We suggest that therapeutic unfractionated heparin in children is titrated to achieve a target anti-Xa range of 0.35 to 0.7 units/mL or an activated partial thromboplastin time range that correlates to this anti-Xa range or to a protamine titration range of 0.2 to 0.4 units/mL (Grade 2C). For neonates and children receiving either daily or bid therapeutic low-molecular-weight heparin, we suggest that the drug be monitored to a target range of 0.5 to 1.0 units/mL in a sample taken 4 to 6 h after subcutaneous injection or, alternatively, 0.5 to 0.8 units/mL in a sample taken 2 to 6 h after subcutaneous injection (Grade 2C).

CONCLUSIONS

The evidence supporting most recommendations for antithrombotic therapy in neonates and children remains weak. Studies addressing appropriate drug target ranges and monitoring requirements are urgently required in addition to site- and clinical situation-specific thrombosis management strategies.

Mitral valve replacement using mechanical prostheses in children: early and long-term outcomes

Compared with mitral repair, mitral valve replacement is an uncommon procedure in children due to associated high mortality and morbidity rates. The present study investigated early and late outcomes after MVR with mechanical prostheses in children at our institution. Between January 1994 and December 2009, 19 children underwent MVR. Mean patient age was 7.6 ± 5.5 years (range 3 months-16 years), and mean body weight was 23.7 ± 15.1 kg (range 5.0-58.1 kg). Mean prosthesis size was 25.8 ± 4.2 mm (range 19-31 mm). There were no operative or late mortalities. Three patients showed decreased left-ventricular function before surgery, and one of them underwent successful heart transplantation due to progressive LV dysfunction at 10 months after MVR. The proportion of patients with freedom from reoperation at 10 years was 94.7 ± 5%. There were no major thromboembolic or bleeding episodes. Although the small number of patients in our study was a limitation, MVR in children was found to result in excellent early and long-term outcomes. It appears that MVR could be considered in children before LV dysfunction develops.