Mitral valve replacement with mechanical prostheses in children: improved operative risk and survival

Mitral Valve Repair in a 15-Month-Old Child With Kingella kingae Endocarditis

Kingella kingae, a Haemophilus parainfluenzae, Aggregatibacter actinomycetemcomitans, Aggregatibacter aphrophilus, Cardiobacterium hominis, Eikenella corrodens, K. kingae (HACEK) organism, is commonly found in the oropharynx. Although it rarely causes endocarditis, it can pose a significant risk to young children. We report a case of K. kingae endocarditis in a previously healthy 15-month-old male who initially presented with symptoms of an upper respiratory infection. Blood cultures taken at 60 hours revealed the presence of K. kingae. Subsequent echocardiogram and brain MRI demonstrated large vegetation on the mitral valve and septic emboli in the right occipital and left posterior parietal lobes. The patient was treated with intravenous ceftriaxone and underwent mitral valve repair with annuloplasty. This case illustrates the presentation of K. kingae endocarditis with initial respiratory symptoms and the subsequent identification of the infection through blood cultures and imaging. For pediatric patients presenting with upper respiratory symptoms, there may be clinical benefit to noninvasive ultrasound imaging to help rule out atypical pathologies like endocarditis.

Mitral valve replacement in children: balancing durability and risk with mechanical and bioprosthetic valves

OBJECTIVES

To investigate if there is still a place for bioprosthetic mitral valve replacement in children by comparing the prosthetic durability and transplant-free survival after bioprosthetic and mechanical mitral valve replacement.

METHODS

We reviewed all mitral valve replacements in children between 1981 and 2020. Bioprosthetic mitral valve replacement cases were individually matched to mechanical mitral valve replacement cases. The incidence rate of a 2nd replacement was calculated using the cumulative incidence function that considered death or transplantation as a competing risk.

RESULTS

The median age at implantation was 3.6 years (interquartile range 0.8-7.9) for the bioprosthetic valve cohort (n = 28) and 3 years (interquartile range 1.3-7.8) for the mechanical valve cohort (n = 28). Seven years after bioprosthetic mitral valve replacement, the cumulative incidence of death or transplantation was 17.9% [95% confidence interval (CI) 6.3-34.1] and the cumulative incidence of a 2nd replacement was 63.6% (95% CI 39.9-80.1). Seven years after mechanical mitral valve replacement, the cumulative incidence of death or transplantation was 28.6% (95% CI 13.3-46) and the cumulative incidence of a 2nd replacement was 10.7% (95% CI 2.6-25.5). Fifteen years after mechanical mitral valve replacement, the cumulative incidence of death or transplantation was 33.6% (95% CI 16.2-52.1) and the cumulative incidence of a 2nd replacement was 41.1% (95% CI 18.4-62.7). The cumulative incidence curves for bioprosthetic and mechanical mitral valve replacement were statistically different for a 2nd valve replacement (P < 0.001) but not for death or transplantation (P = 0.33).

CONCLUSIONS

There is no difference in transplant-free survival after bioprosthetic and mechanical mitral valve replacement in children. The lifespan of bioprosthetic mitral valves remains limited in children because of structural valve failure due to calcification. After 15 years, 40% of mechanical valves were replaced, primarily because of patient-prosthesis mismatch related to somatic growth.

Long-Term Outcomes of Atrioventricular Valve Surgery in Patients with Functional Single Ventricle: Should We Avoid Valve Replacement?

Atrioventricular valve regurgitation (AVVR) is associated with increased morbidity and mortality in patients with single ventricle physiology. The purpose of this study was to evaluate the long-term results of the surgical management of AVVR and to analyze the effects of AV valve replacement. The medical records of 38 single ventricle patients who underwent atrioventricular valve surgery more than once between January 2001 and March 2018 were retrospectively reviewed. We analyzed and compared clinical data of patients who underwent valve replacement as an initial treatment (n = 8) for AVVR with patients who initially underwent valve repair (n = 30). The median follow-up duration was 98.1 months (range, 0.9-209.6 months). There was one early mortality and seven late mortalities. Freedom from reoperation between the two groups at 15 years of follow-up was significantly different: 18.3% in the repair group and 100% in the replacement group (p = 0.013). The replacement group showed a better overall survival rate (100%) at 15 years than the repair group (68.5%) without statistical significance (p = 0.097). All mortalities occurred in the repair group. Nine patients in the repair group (30%) and one patient in the replacement group (12.5%) showed preoperative ventricular dysfunction. RV-type single ventricle with atrioventricular (AV) valve annular dilatation was found out as a risk factor of AVV replacement both in univariate (p = 0.04) and multivariate (p = 0.004) analysis. AV valve replacement might be considered as a primary treatment option for patients who have an annular dilation with an RV-type single ventricle rather than repeated valvuloplasty.

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.

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.

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.

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.

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.

Prosthetic Valve Replacement in Adolescents with Rheumatic Heart Disease

To assess long-term survival and anticoagulant-related complications after mechanical valve replacement in adolescents with rheumatic heart disease, 88 patients aged ≤ 18 years were prospectively followed up for 10 years (404.2 patient-years). There were 58 (65.9%) boys and 30 (34.1%) girls, with a mean age of 15.4 ± 2.1 years. Mitral regurgitation was detected in 39 (44.3%) patients, and both mitral and aortic regurgitation in 15 (17%). Ball valves were inserted in 52 (59.1%) patients, bileaflet valves in 31 (35.2%), and single-disc valves in 5 (5.7%). There were 4 (4.5%) hospital deaths and 11 late deaths. Patient survival at 30 days, 3 months, 1, 5, and 10 years was 95.5%, 93.2%, 87.5%, 82.9%, and 82.9%, respectively. Mechanical valve thrombosis occurred in 4 patients; it was fatal in 3 of them. Three patients died from stroke. Severe hemorrhage required hospital admission in 4 (4.5%) patients. Mechanical valve replacement in adolescents, with careful follow-up and anticoagulation, has acceptable long-term results.

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.

Bleeding and Thrombotic Emergencies in Pediatric Cardiac Intensive Care

Children in the cardiac intensive care unit (CICU) with congenital or acquired heart disease are at risk for hematologic complications, both hemorrhage and thrombosis. The overall incidence of hematologic complications in the CICU is unknown, but risk factors and target groups have been identified where the essential physiologic balance between bleeding and clotting has been disrupted. Although the best management of life-threatening bleeding and clotting is prevention, the cardiac intensivist is often faced with managing life-threatening hematologic events involving patients from within the unit or those who present from outside. Part I of this review deals with the propensity of children with congenital and acquired heart disease to complications of both bleeding and clotting, and includes discussions of perioperative bleeding, thromboses in single-ventricle patients, clotting of Blalock-Taussig shunts and thrombotic complications of mechanical valves. Part II deals with the subject of stroke in children with heart disease. Part III reviews monitoring the effectiveness of anticoagulation and thrombolysis in the CICU. Currently available diagnostics modalities, medications and management strategies are reviewed and future directions discussed.

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.

Ross-kabbani operation in an infant with mitral valve dysplasia

Background. Mitral valve replacement can be very difficult to obtain in infants because the valve annulus diameter can be smaller than the available prosthesis. Case Report. We describe the case of a 2-month-old female weighing 3.5 kg affected by mitral valve dysplasia leading to severe valve stenosis. Despite full medication, the clinical conditions were critical and surgery was undertaken. The mitral valve was unsuitable for repair and the orifice of mitral anulus was 12 mm, too small for a mechanical prosthesis. Therefore, a Ross-Kabbani operation was undertaken, replacing the mitral valve with the pulmonary autograft and reconstructing the right ventricular outflow tract with an etherograft. Results. The postoperative course was uneventful and the clinical conditions are good at 4-month follow-up. Conclusion. The Ross-Kabbani operation can be an interesting alternative to mitral valve replacement in infants when valve repair is not achievable and there is little space for an intra-annular mechanical prosthesis implant.

Mitral valve replacement with the pulmonary autograft in children: a word of caution

A 4(1/2)-month-old patient who underwent mitral valve replacement for congenital mitral stenosis using a pulmonary autograft is reported. Failure of the autograft resulted in pulmonary hypertension, leading to pulmonary regurgitation in the reconstructed right ventricular outflow tract, then tricuspid regurgitation, refractory right heart failure, and death. Caution should be exercised in applying this procedure with children, particularly those at risk for pulmonary hypertension.

Comparison of mechanical and biological prostheses when used to replace heart valves in children and adolescents with rheumatic fever

OBJECTIVE

To assess the outcomes in children and adolescents with rheumatic fever of the implantation of mechanical as opposed to biological heart valves.

METHODS

We assessed 73 patients with rheumatic heart disease under the age of 18 years, who underwent replacement of heart valves between January, 1996, and December, 2005, at the National Institute of Cardiology in Rio de Janeiro, Brazil. Of the group, 71 patients survived, and were divided into a group of 52 receiving mechanical prostheses, and 19 with biological prostheses. We compared endpoints between the groups in terms of mortality, reoperation, haemorrhage, and stroke. Survival curves were estimated using the Kaplan-Meier method and were compared by the Mantel (log-rank) test.

RESULTS

Overall mortality was 8.2%. In those receiving mechanical prostheses, 2 (3.8%) patients died, 5 (9.6%) underwent reoperation, 2 (3.8%) suffered severe haemorrhage, and 3 (5.8%) had strokes. In those receiving biological valves, 2 (10.5%) patients died, and 4 (21%) underwent reoperation. After 2, 4, and 8 years, overall survival was 96%, 93% and 86%, respectively, with a borderline difference between the groups (p = 0.06). The probabilities of remaining free from reoperation (p = 0.13), and from combined endpoints, showed no statistically significant difference between the groups (p = 0.28).

CONCLUSIONS

Patients with mechanical prostheses had lower mortality and required fewer reoperations, but when all combined endpoints were considered, the groups did not differ. The biological prosthesis proved to be a good option for cardiac surgery in children and adolescents with difficulties or risks of anticoagulation.

Antithrombotic therapy in neonates and children: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition)

This chapter about antithrombotic therapy in neonates and children is part of the Antithrombotic and Thrombolytic Therapy: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs, and Grade 2 suggests that individual patient values may lead to different choices (for a full understanding of the grading, see Guyatt et al in this supplement, pages 123S-131S). In this chapter, many recommendations are based on extrapolation of adult data, and the reader is referred to the appropriate chapters relating to guidelines for adult populations. Within this chapter, the majority of recommendations are separate for neonates and children, reflecting the significant differences in epidemiology of thrombosis and safety and efficacy of therapy in these two populations. Among the key recommendations in this chapter are the following: In children with first episode of venous thromboembolism (VTE), we recommend anticoagulant therapy with either unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) [Grade 1B]. Dosing of IV UFH should prolong the activated partial thromboplastin time (aPTT) to a range that corresponds to an anti-factor Xa assay (anti-FXa) level of 0.35 to 0.7 U/mL, whereas LMWH should achieve an anti-FXa level of 0.5 to 1.0 U/mL 4 h after an injection for twice-daily dosing. In neonates with first VTE, we suggest either anticoagulation or supportive care with radiologic monitoring and subsequent anticoagulation if extension of the thrombosis occurs during supportive care (Grade 2C). We recommend against the use of routine systemic thromboprophylaxis for children with central venous lines (Grade 1B). For children with cerebral sinovenous thrombosis (CSVT) without significant intracranial hemorrhage (ICH), we recommend anticoagulation initially with UFH, or LMWH and subsequently with LMWH or vitamin K antagonists (VKAs) for a minimum of 3 months (Grade 1B). For children with non-sickle-cell disease-related acute arterial ischemic stroke (AIS), we recommend UFH or LMWH or aspirin (1 to 5 mg/kg/d) as initial therapy until dissection and embolic causes have been excluded (Grade 1B). For neonates with a first AIS, in the absence of a documented ongoing cardioembolic source, we recommend against anticoagulation or aspirin therapy (Grade 1B).

Mitral valve replacement in infants and children 5 years of age or younger: evolution in practice and outcome over three decades with a focus on supra-annular prosthesis implantation

OBJECTIVE

Successful mitral valve replacement in young children is limited by the lack of small prosthetic valves. Supra-annular prosthesis implantation can facilitate mitral valve replacement with a larger prosthesis in children with a small annulus, but little is known about its effect on the outcomes of mitral valve replacement in young children.

METHODS

One hundred eighteen children underwent mitral valve replacement at 5 years of age or younger from 1976-2006. Mitral valve replacement was supra-annular in 37 (32%) patients.

RESULTS

Survival was 74% +/- 4% at 1 year and 56% +/- 5% at 10 years but improved over time (10-year survival of 83% +/- 7% from 1994-2006). Factors associated with worse survival included earlier mitral valve replacement date, age less than 1 year, complete atrioventricular canal, and additional procedures at mitral valve replacement, but not supra-annular mitral valve replacement. As survival improved during our more recent experience, the risks of supra-annular mitral valve replacement became apparent; survival was worse among patients with a supra-annular prosthesis after 1991. A pacemaker was placed in 18 (15%) patients within 1 month of mitral valve replacement and was less likely in patients who had undergone supra-annular mitral valve replacement. Among early survivors, freedom from redo mitral valve replacement was 72% +/- 5% at 5 years and 45% +/- 7% at 10 years. Twenty-one patients with a supra-annular prosthesis underwent redo mitral valve replacement. The second prosthesis was annular in 15 of these patients and upsized in all but 1, but 5 required pacemaker placement for heart block.

CONCLUSIONS

Supra-annular mitral valve replacement was associated with worse survival than annular mitral valve replacement in our recent experience. Patients with supra-annular mitral valve replacement were less likely to have operative complete heart block but remained at risk when the prosthesis was subsequently replaced.

Replacement of the systemic atrioventricular valve with a mechanical prosthesis in children aged less than 6 years: Late clinical results of survival and subsequent replacement

OBJECTIVE

We analyzed the survival, clinical course, and role of prosthesis-patient mismatch after systemic atrioventricular valve replacement in children.

METHODS

From 1974 to 2006, 69 patients underwent systemic atrioventricular valve replacement (median age 1.2 years, range 1.1 months to 5.4 years), with 17 patients requiring re-replacement of the systemic atrioventricular valve. Prosthesis-patient relationship was analyzed by comparing (1) the prosthetic valve diameter and the predicted annulus diameter based on the body surface area and (2) the prosthetic valve diameter and the measured annulus diameter.

RESULTS

Survival was 73% at 1 year and 65% at 5, 10, and 15 years. Age, weight, body surface area, predicted annulus diameter, prior surgery, underlying disease, and ratio of prosthetic valve diameter to body weight were significant predictors of death. Variables associated with re-replacement of the systemic atrioventricular valve were body surface area, prosthetic valve diameter, predicted annulus diameter, and presence of multiple left-sided obstructive lesions. The majority of patients received a prosthesis larger than the predicted annulus diameter. There was good correlation between the prosthetic valve diameter and the measured annulus diameter (r = 0.85). Mismatch, as described by the difference in z scores of prosthetic valve diameter and measured annulus diameter, was not a significant predictor of death or re-replacement of the systemic atrioventricular valve.

CONCLUSIONS

Although valve replacement is considered the last therapeutic option after failed attempts of valvuloplasty, long-term outcome is favorable. Selection of the prosthesis is made on the basis of the measured annulus diameter. An elevated ratio of prosthetic valve diameter to body weight is associated with patients with low body weight or a large native annulus in dilated ventricles.

Medium-term follow-up of mechanical valves inserted in children

OBJECTIVE

We reviewed our experience with mechanical valves inserted between 1988 and 2002 in children aged 15 years or younger.

METHODS

Hospital files were extracted retrospectively. Follow-up was completed by March 2005.

RESULTS

Of 41 patients, we inserted a valve in atrioventricular position in 27 children, having a median age of 3.1 years, ranging from 0.4 to 14.5 years, and in aortic position in the remaining 14, having a median age of 13.5 years, and a range from 7.0 to 14.9 years. For the valves inserted in atrioventricular position, the underlying disease was congenital in 23, rheumatic in two, post-endocarditic in one, and Marfan's syndrome in one. Mean follow-up was 7.7 years, with standard deviation of 5.3, giving a total follow-up of 209 patient years. Mortality at 30 days was 7%, and survival was 73% at up to 16 years follow-up. Events related to anticoagulation were seen in 3 patients, corresponding to 1.4% per patient year. In 6 patients (22%), heart block ensued which required implantation of a pacemaker treatment, and 5 patients (19%) had reoperations. For the implantations in aortic position, the underlying disease was congenital in 13, stenosis in 10 and insufficiency in three, and post-endocarditis in one. Mean follow-up was 6.8 years, with standard deviation of 4.6, giving a total of 95 patient years. We lost one patient within 30 days (7.7% mortality), and survival was 77% at up to 13 years follow-up. There were no incidents of thrombosis, nor events related to anticoagulation, but one patient (7%) needed insertion of a pacemaker due to a perioperative heart block, and one (7%) required new valvar replacement.

CONCLUSIONS

Although preferably avoided, mechanical valves can be implanted in children with an acceptable mortality and morbidity, and good long-term results.

Risk factors for adverse outcomes after surgery on the systemic atrioventricular valve in 109 children

In contrast to older patients, children and young adults rarely have isolated disease of the systemic atrioventricular valve. Stenosis and/or regurgitation of the systemic atrioventricular valve, however, frequently coexist with complex congenital cardiac disease. In addition, most patients undergoing surgery on the systemic atrioventricular valve have had previous intracardiac repairs.

Systemic mechanical heart valve replacement in children under 16 years of age

We report the early and late outcome following left-sided mechanical heart valve replacement in children. Between 10/1981 and 02/2001, 27 children (13 male, mean age 7.2 +/- 5.2 years, range 0.53-15.7 years) underwent mechanical mitral (MVR 16), aortic (AVR 9) or double valve replacement (DVR 2) with St. Jude Medical valves. Eighteen children (66.7%) had undergone previous cardiac surgery. Valve disease was congenital in 23, due to endocarditis in 2 and rheumatic in 2 patients. Concomitant cardiac surgery was performed in 12 patients (44.4%). Operative mortality was 3.7% (1/27). Perioperative complications were complete heart block (5) and myocardial infarction (1). Mean follow-up was 6.5+/-5.9 years (range 0.4-19 years, total 169.9 patient-years). There was one valve-related late death due to mitral valve thrombosis without phenprocoumon. Actuarial survival after 1, 5 and 10 years was 93, 93 and 93%. Late complications included endocarditis (2), minor hemorrhagic event (1) and stroke (1). Overall 10-year freedom from any anticoagulation-related adverse event under phenprocoumon was 91% (1.3%/patient year). Eight patients required reoperations: re-MVR (5; outgrowth of the prostheses (3), pannus overgrowth (2)), closure of paravalvular leak after AVR (2), and re- DVR (1; endocarditis). Actuarial freedom from reoperation after 1, 5 and 10 years was 96, 88 and 76%.

CONCLUSION

Mechanical valve prostheses are a valuable option for left-sided heart valve replacement in pediatric patients with good results. Operative mortality and the incidence of any valve-related events as endocarditis, reoperation, thromboembolism or anticoagulation related bleeding is acceptable.

Congenital mitral valve surgery: techniques and results

PURPOSE OF REVIEW

Congenital lesions of the mitral valve are rare. Conservative surgery is recognized as the best option. In complex anatomy, however, replacement is the only solution to achieve an acceptable result. This review aims to study the long-term follow-up of classical treatments, conservative or replacement, and to examine new technical advances.

RECENT FINDINGS

The long-term results of conservative surgery are confirmed with a low incidence of reoperation except in mitral valve stenosis. The Ross II operation using a pulmonary autograft is a difficult technique that may be useful in the youngest patient group when prosthetic devices cannot be used.

SUMMARY

In the last few years, surgery of congenital mitral valve lesions has gained from echocardiography, which shows the exact function and anatomy of the mitral valve. The tendency is to avoid multistage operations. Valve replacement by biologic material (Ross II) is still under clinical evaluation.

Mitral valve replacement in children under 3 years of age

OBJECTIVE

This study was undertaken to review our experience of mitral valve replacement in children under 3 years of age.

METHODS

Between January 1990 and May 2004, 18 patients under 3 years of age underwent a total of 20 mitral valve replacements using a bileaflet mechanical prosthetic valve. There were 9 males and 11 females. The age at surgery ranged from 3 months to 3 (mean=1.02 +/- 0.72) years and body weight varied between 3.4 and 13.2 (mean=7.08 +/- 2.74) kg.

RESULTS

There were 4 early and 2 late deaths, and these occurred in severe cases aged less than 1 year of age. Re-replacement of mitral valve was required in 3 patients (valve thrombosis in 2 and pannus formation in 1). Orifice size of the implanted prosthesis (OS) as compared with the predicted normal size of the mitral valve (NS) was well correlated with maximum transprosthetic flow velocity estimated by Doppler echocardiography. In this study, the OS/NS>0.65 was maintained in all patients, and none required re-replacement because of prosthesis-patient mismatch.

CONCLUSION

Patients less than 1 year of age had significant mortality and morbidity. The results were satisfactory in the remainder (1-3 years). During this follow-up period, none required re-replacement due to somatic growth, but it will be an unavoidable problem in the future. The OS/NS, which can be checked with a regular physical examination, may serve as a guide to determine the most appropriate timing for the second surgery.

Current Management of Severe Congenital Mitral Stenosis

Background— Severe congenital mitral stenosis (MS) is a rare anomaly that is frequently associated with additional left heart obstructions. Anatomic treatments for congenital MS include balloon mitral valvuloplasty (BMVP), surgical mitral valvuloplasty (SMVP), and mitral valve replacement (MVR), although the optimal therapeutic strategy is unclear.

Methods and Results— Between 1985 and 2003, 108 patients with severe congenital MS underwent BMVP or surgical intervention at a median age of 18 months (range 1 month to 17.9 years). Anatomic subtypes of MS were “typical” congenital MS in 78 patients, supravalvar mitral ring in 46, parachute mitral valve in 28, and double-orifice mitral valve in 11, with multiple types in ≈50% of patients. Additional left heart anomalies were present in 82 patients (76%). The first MS intervention was BMVP in 64 patients, SMVP in 33, and MVR in 11. BMVP decreased peak and mean MS gradients by a median of 33% and 38%, respectively ( P <0.001), but was complicated by significant mitral regurgitation in 28%. Cross-sectional follow-up was obtained at 4.8±4.2 years. Overall, Kaplan-Meier survival was 92% at 1 month, 84% at 1 year, and 77% at 5 years, with 69% 5-year survival during the first decade of our experience and 87% since ( P =0.09). Initial MVR and younger age were associated with worse survival. Survival free from failure of biventricular repair or mitral valve reintervention was 55% at 1 year among patients who underwent BMVP and 69% among patients who underwent supravalvar mitral ring resection initially. Among patients who underwent BMVP, survival free from failure of biventricular repair or MVR was 79% at 1 month and 55% at 5 years, with worse outcome in younger patients and those who developed significant postdilation mitral regurgitation.

Conclusions— BMVP effectively relieves left ventricular inflow obstruction in most infants and children with severe congenital MS who require intervention. However, surgical resection is preferable in patients with MS due to a supravalvar mitral ring. Five-year survival is relatively poor in patients with severe congenital MS, with worse outcomes in infants and patients undergoing MVR, but has improved in our more recent experience. Many patients have undergone second procedures for either recurrent/residual MS or mitral regurgitation resulting from dilation-related disruption of the mitral valve apparatus.

Redo Mitral Valve Replacement in Children

BACKGROUND

Despite excellent results with current techniques of mitral valve repair, some children still require mitral valve replacement (MVR). Of necessity, a certain percentage of these children need valve rereplacement (redo MVR).

METHODS

Of 82 MVRs at our institution since 1988, 22 were redo MVRs in 21 children aged 1.4-21 years (mean 9.8 +/- 5.6 years). Interval from initial MVR was 1 month to 18 years (mean 5.8 +/- 4.9 years). Reoperation indication was primarily stenosis in 13 (usually pannus formation), regurgitation in 4, valve thrombosis or embolism in 4, and endocarditis in 1. The initial valve was mechanical in 18 and xenograft in 4.

RESULTS

During redo MVR, 8 of 22 (36%) patients had additional procedures including left ventricular outflow tract obstruction relief or aortic valve replacement in 4 and tricuspid valve repair in 2. The new mitral valve was mechanical in 20 and xenograft in 2. Median valve size increased from 21 mm to 25 mm although 7 valves were not upsized on rereplacement (average valve size increase was 3.3 +/- 1 mm). Only 2 patients (9%) needed a new pacemaker. There were no hospital deaths. Six children developed end-stage heart failure and underwent successful cardiac transplantation 3 to 32 (mean 12.1 +/- 10.0) months, postoperatively. On follow-up of 1 month to 7.7 years (mean 2.5 +/- 2.3 years) there has been only one late death of an unrecognized coronary artery anomaly.

CONCLUSIONS

Redo MVR in children can be performed safely with low morbidity and mortality. A larger prosthesis can often be placed in these children. A surprisingly high percentage of patients eventually require transplantation, perhaps reflecting unnecessary delay in referral for redo MVR.

Complications of supra-annular mitral valve placement in infants

Two infants underwent supra-annular placement of prosthetic mitral valves. The objective of this strategy was to insert a larger valve and delay replacement. This approach was initially successful but by two and three years later the patients developed impairment of cardiac function. The prosthesis decreased the volume and compliance of the left atrium causing high left atrial and pulmonary venous pressures. The "ventricularised" atrium below the prosthesis dilated. In neither case was it possible to delay second valve replacement.

Outcomes of mitral valve replacement in children: A competing-risks analysis

OBJECTIVE

We sought to define patient characteristics, outcomes, and associated factors after mitral valve replacement in children.

METHODS

We included 104 children undergoing at least one mitral valve replacement between 1980 and 2003 and reviewed clinical records. Competing-risks methodology was used to determine time-related prevalence and associated risk factors after initial mitral valve replacement for death and repeat replacement.

RESULTS

The underlying mitral valve disease was congenital in 83%, rheumatic in 13%, Marfan syndrome in 3%, and isolated endocarditis in 1%, with 64% having primarily regurgitation, 16% having stenosis, 20% having both, and 32% having undergone previous valvotomy, valvuloplasty, or repair. There were 137 valve replacements, with 26 patients having more than one. Valve prosthesis type was St Jude Medical in 37%, Bjork-Shiley in 25%, Carbomedics in 20%, Ionescu-Shiley in 10%, and other types in 8%. Both early and late complications were common. Median age at the initial replacement was 5.9 years (range, birth to 19 years). Competing-risks analysis predicted 19% to have died at 15 years after initial replacement, with risk factors including noncongenital valve morphology, lower weight, and longer duration of cardiopulmonary bypass. A repeat replacement was predicted for 71%, with risk factors including the presence of multiple left-heart obstructive lesions and Ionescu-Shiley valve prosthesis.

CONCLUSIONS

Mitral valve replacement might be necessary in children with extremely dysplastic valves and severe hemodynamic impairment or after failed repair. However, with the appropriate selection of the prosthetic valve and reduction of cardiopulmonary bypass time, surgeons might decrease mortality and increase prosthesis longevity.

Mitral valve replacement for children with a small annulus using ATS open pivot prosthesis

OBJECTIVES

The present study was conducted to review our experience of mitral valve replacement (MVR) in small children with the ATS open pivot prosthesis.

METHODS

Between January 1999 and March 2002, 14 patients (7 males and 7 females) underwent a total of 15 ATS MVRs; 16AP in 9, 18AP in 3, and 20AP in 3 occasions. The mean age and body weight at operation were 1.1 +/- 0.7 (range 0.2 to 2.7) years and 6.8 +/- 2.6 (range 2.8 to 12.5) kg, respectively.

RESULTS

There were 2 early and 2 late deaths, each non-valve related. Excluding one patient, the orifice size of the prosthesis was larger than the predicted normal size of the mitral valve for the age. The postoperative Doppler echocardiogram demonstrated normal maximal flow velocity across the prosthesis. There was no morbidity among survivors except for the patient who developed a stuck and immobile valve disc 10.2 months after the operation and required re-replacement.

CONCLUSIONS

Our experience shows that MVR with the ATS open pivot prosthesis is a promising surgical option for small children.