[Supra-annular Mitral Valve Replacement Using a Composite Valve for an Infant with Acute Rupture of Chordae Tendineae]

Acute rupture of the chordae tendineae of the mitral valve could lead to severe mitral regurgitation and circulatory collapse in infants. Mitral valve replacement may be often challenging because of the valve-annulus size mismatch in small infants when mitral valve repair cannot be accomplished. We present an infant with acute massive rupture of the chordae tendineae of the mitral valve who successfully underwent supra-annular mitral valve replacement using the short composite valve of an expanded polytetrafluoroethylene( ePTFE) graft and a mechanical valve. His mechanical valve has been functioning without complications such as thrombosis and pulmonary venous obstruction for 20 months after surgery. This technique could be helpful even infants with acute rupture of the chordae tendineae of the mitral valve whose left atrium may not be dilated.

A Case of Successful Biventricular Repair of the Transposition of the Great Arteries with a Coronary Anomaly Associated with an Atrioventricular Septal Defect

The transposition of the great arteries (TGA) associated with a complete atrioventricular septal defect is a rare and serious congenital cardiac anomaly. In this report, we describe the successful biventricular repair of a TGA with a complete atrioventricular septal defect in an infant. Due to the low body weight of the patient and a complex coronary pattern anomaly, an arterial switch operation was executed, with the Mee procedure and pulmonary arterial banding as initial palliative measures when the infant was 22 days old and weighed 2.5 kg. Subsequently, atrioventricular septal defect repair using the modified one-patch method was performed when the patient was 1.3 years old and weighed 8.8 kg. Remarkably, the postoperative course of the patient demonstrated no notable incidents. To our knowledge, this is the first time a two-stage strategy was applied to repair these complex defects, presenting a promising approach for managing similar cases in future medical practice.

Late bacterial endocarditis after percutaneous atrial septal defect closure

Percutaneous atrial septal defect closure is widely used as an alternative to surgical repair in many hospitals. Infective endocarditis related to occluding devices is commonly known, but following that atrial septal defect closure with a device in a child is rare. This report describes an 11-year-old girl who developed late-stage bacterial endocarditis following incomplete endothelialisation after a percutaneous procedure.

The Lymphatic Circulation in Adaptations to the Fontan Circulation

Failing Fontan continues to be major problem for patients on the univentricular pathway. Failing Fontan is often complicated by chylothorax, plastic bronchitis and protein loosing enteropathy. The role of lymphatic circulation in Fontan circulation is still being researched. Newer imaging modalities give insight into the role of abnormal dilatation and retrograde flow in lymphatic channels post Fontan. Interventional strategies targeting abnormal lymphatic channels, provides an alternative management strategy for patients with failing Fontan. This review focuses on the role of lymphatic system in adaptations to Fontan circulation.

An increased incidence of conduit endocarditis in patients receiving bovine jugular vein grafts compared to cryopreserved homograft for right ventricular outflow reconstruction

BACKGROUND

We compared the outcome of patients receiving bovine jugular vein grafts versus cryopreserved homografts for right ventricular outflow tract reconstruction.

METHODS

Between 2000 and 2012, 379 conduits (244 bovine jugular vein grafts, 135 homografts) were implanted in 298 patients (median age 50 months) with a median follow-up of 3.4 years.

RESULTS

Freedom from reoperation at 1, 5, and 7 years was 96.3%, 79.3%, and 64.2% after bovine jugular vein graft and 94.6%, 75.7%, and 68.6% after homograft insertion (p = 0.086). There were 24 cases of endocarditis, 23 associated with bovine jugular vein grafts (9.4%) and 1 associated with a homograft (0.7%; p < 0.001) at median follow-up of 44 months (range, 15 days to 10 years) after conduit implantation. After endocarditis, 15 of 24 conduits were replaced. Three patients had recurrent endocarditis in the revised conduit. Multivariate logistic regression analysis showed age less than 3 years and endocarditis to be significant risk factors associated with conduit replacement. Age more than 3 years and bovine jugular vein grafts were significant risk factors for graft endocarditis. Patients more than 3 years of age at bovine jugular vein graft implantation had significantly lower freedom from reoperation (p = 0.01).

CONCLUSIONS

Compared with homograft conduits, the use of bovine jugular vein grafts for right ventricular outflow tract reconstruction was associated with a significantly higher incidence of bacterial endocarditis and conduit deterioration in older children at our institution. That may influence decision making regarding conduit choice for right ventricular outflow tract reconstruction. Patients and practitioners should be aware of the late risks of bacterial endocarditis after bovine jugular vein graft implantation.

Right ventricular and tricuspid valve remodeling after bidirectional cavopulmonary anastomosis

BACKGROUND

There are few investigations of the changes in tricuspid valve (TV) and right ventricular (RV) morphology following bidirectional cavopulmonary anastomosis (BCPA).

METHODS AND RESULTS

The 2-D echocardiograms of 35 children (male, n=23; female, n=12; median age, 6 months; range, 3-10 months) with hypoplastic left heart syndrome, 1 month before and after BCPA performed between 2005 and 2011, were retrospectively reviewed. Patients who underwent TV repair at BCPA were excluded. From the 4-chamber view, the coaptation length, vena contracta width and RV end-diastolic area before and after BCPA were measured and indexed to surface area. The severity of tricuspid regurgitation was graded qualitatively. After BCPA, RV end-diastolic area decreased from 2,951 ± 584 to 2,580 ± 591 mm(2)/m(2) (P<0.001). The coaptation length of the anterior leaflet (8.8 ± 5.8 vs. 11.0 ± 6.2 mm/m(2), P=0.0014) and of the septal leaflet (13.5 ± 5.3 vs. 15.8 ± 5.4mm/m(2), P=0.0072) increased after BCPA. The vena contracta width decreased (5.8 ± 4.9 vs. 4.3 ± 4.2 mm/m(2), P=0.035), although there was no change in tricuspid regurgitation grade after BCPC (1.4 ± 0.7 vs. 1.4 ± 0.9, P=0.234).

CONCLUSIONS

In children with hypoplastic left heart syndrome after BCPA, the coaptation length of the anterior and septal leaflets of the TV improved concomitantly with vena contracta width and RV end-diastolic area despite unchanged tricuspid regurgitation grade. This suggests that favorable RV and TV remodeling accompanies the reduction in RV volume load following BCPA. 

Extracorporeal membrane oxygenation following Norwood stage 1 procedures at a single institution

Extracorporeal membrane oxygenation (ECMO) is an important circulatory assist for children with refractory cardiopulmonary dysfunction, but its role and indications after a stage 1 Norwood procedure are controversial. We assessed outcomes and risk factors in patients who underwent a Norwood palliation and ECMO at our institution. We retrospectively reviewed all patients who underwent a Norwood procedure and were supported with ECMO between January 1998 and January 2010. Of the 91 children who underwent a Norwood procedure during the study period, there were 15 postoperative runs of ECMO in 12 patients. The diagnoses of the patients included five with hypoplastic left heart syndrome, five with a hypoplastic left heart syndrome variant, and two with critical aortic stenosis. A total of four patients underwent bilateral pulmonary artery banding, and two patients underwent aortic valvuloplasty before the stage 1 Norwood procedure. The mean age of the patients was 28±30 days, and mean body weight was 2.6±0.5kg at the induction of ECMO. The indications for ECMO were low cardiac output in six children, circulatory collapse needing cardiopulmonary resuscitation in six children, and hypoxemia in three children. Five of the 12 patients were successfully weaned from ECMO. The significant risk factors for the inability to be weaned from ECMO were a history of circulatory collapse requiring cardiopulmonary resuscitation, and the induction of ECMO in the intensive care unit. Induction of ECMO may be considered earlier when hemodynamics are unstable in impaired patients following a stage 1 Norwood procedure to avoid circulatory collapse.

Combination of continuous irrigation and vacuum-assisted closure is effective for mediastinitis after cardiac surgery in small children

There is still no consensus on the optimal management to treat pediatric mediastinitis. We assessed the efficacy of continuous irrigation and vacuum-assisted closure (VAC) for mediastinitis in children. This study retrospectively reviewed 20 patients aged <5 years with mediastinitis from December 2002 to December 2009. The median age at the onset was 12 months (0.6-60 months), and the median body weight was 6.9 kg (3.1-15.3 kg). Continuous irrigation was applied for extensive mediastinitis or unstable hemodynamic cases and VAC for localized or ineffective cases after continuous irrigation. A 2-4-week course of intravenous antibiotics was administered after sternal closure. Continuous irrigation was initially applied in 19 patients and VAC in one patient. VAC was employed in six patients because of recurrent or prolonged mediastinitis after continuous irrigation. All patients underwent direct sternal closure without any flap. The median duration of the hospital stay was 49.5 days (15-158 days). Although two patients died of low cardiac output, 18 children survived and had no recurrence after the discharge during a median follow-up of 14 months (1-81 months). The combination of continuous irrigation and VAC is, therefore, considered to be a safe and effective option to minimize the morbidity and mortality in pediatric mediastinitis.

Effect of modified ultrafiltration on postoperative course in neonates with complete transposition of the great arteries undergoing arterial switch operation

BACKGROUND

The purpose of the present study was to evaluate the effect of modified ultrafiltration (MUF) on neonates with transposition of the great arteries (TGA) undergoing arterial switch operation.

METHODS AND RESULTS

The current study included 36 neonates who underwent an arterial switch operation between 1998 and 2006. Arterio-venous MUF was done in 15 patients (MUF-treated group) and the other 21 patients were controls. Parameters included hematocrit, hemodynamics, pulmonary function, drain loss, leak of peritoneal fluid, length of intubation, and intensive care unit (ICU) stay. The hematocrit increased from 34+/-2% to 47+/-4% in the MUF-treated group. Blood pressure in the MUF-treated group was significantly increased without any change of central venous or left atrial pressure. Post-operative oxygenation in the MUF-treated group was greater than that of the control group (P/F ratio: 258+/-92 vs 170+/-100 mmHg, p<0.05), which did not contribute to decrease in intubation time (54+/-33 vs 52+/-29 h, p=NS). Post-operative chest drain loss and peritoneal fluid leak were comparable. The ICU stay in the MUF-treated group was significantly shorter than that in the controls (101+/-34 vs 139+/-42 h, p<0.05).

CONCLUSIONS

MUF brought improvement in blood pressure and gas exchange capacity and subsequent shorter ICU stay. MUF did not have significant impact on intubation time and capillary leak.

Feasibility of a Tiny Centrifugal Blood Pump (TinyPump) for Pediatric Extracorporeal Circulatory Support

In this study, the performances of the TinyPump (priming volume 5 mL) system including the pediatric cannulae (Stöckert Pediatric Arterial Cannulae 2.6, 3.0, and 4.0 mm, Stöckert Instruments GmbH, Munich, Germany; Polystan 20-Fr Venous Catheter, MAQUET GmbH, Rastatt, Germany) and an oxygenator (Terumo Capiox RX05 Baby-RX, Terumo Cardiovascular Systems Co., Tokyo, Japan) were studied in vitro followed with preliminary ex vivo studies in 20-kg piglets. In vitro results revealed that the TinyPump system met the requirements for pump speed, pump flow, and pressure drop as extracorporeal circulatory support during open heart surgery and extracorporeal membrane oxygenation (ECMO) in pediatric patients. In 2-h ex vivo studies using 20-kg piglets where the blood contacting surface of the TinyPump was coated with a biocompatible phospholipid polymer, the plasma-free hemoglobin levels remained less than 5.0 mg/dL and no thrombus formation was observed inside the pump. The TinyPump system including the oxygenator and connecting circuits resulted in an overall priming volume of 68 mL, the smallest ever reported. The TinyPump can be a safe option for pediatric circulatory support during open heart surgery and ECMO without requiring blood transfusion.

Advantages of temporary venoatrial shunt using centrifugal pump during bidirectional cavopulmonary shunt

Single-ventricle palliation without the use of cardiopulmonary bypass carries advantages that reduce systemic edema and inflammatory responses; however, simple clamping of the superior vena cava (SVC) without a temporary shunt leads to increase in cerebral venous pressure and subsequent decrease in cerebral blood flow during bidirectional cavopulmonary shunt (BCPS). We report our experience of BCPS, using a centrifugal pump-assisted temporary shunt. The criteria included an unrestrictive interatrial communication, the absence of atrioventricular valve regurgitation, and the existence of an antegrade pulmonary blood flow. From August 2000, 14 children with single-ventricle physiology met the criteria. The mean age was 1.0 +/- 0.9 years, and the mean weight was 8.4 +/- 2.6 kg. A temporary shunt was established between the SVC and the right atrium with right-angle cannulae, which were connected to a centrifugal pump to accelerate the blood flow from the SVC to the right atrium. All patients tolerated the procedure. Mean central venous pressure was 17 +/- 4 mm Hg, and transcutaneous oxygen saturation was maintained at 77 +/- 8% during anastomosis. No patients required blood transfusion. There were no postoperative neurological complications. The centrifugal pump-assisted temporary shunt offered safer and more effective circulatory support than other shunt systems, with excellent venous drainage in pediatric patients undergoing BCPS.