Michele Borisuk

Accelerated Degeneration of a Bovine Pericardial Bioprosthetic Aortic Valve in Children and Young Adults

Background— Experience with aortic valve replacement (AVR) with current-generation pericardial bioprostheses in young patients is limited. The death of a child with accelerated bioprosthetic aortic stenosis prompted enhanced surveillance of all such patients at our institution. Methods and Results— We reviewed records of 27 patients who had undergone AVR (median follow-up, 13.7 months) with a bovine pericardial bioprosthesis at ⩽30 years of age. In the Mitroflow LXA valve group (n=15), freedom from valve failure was 100% at 1 year, 53% (95% confidence interval, 12–82) at 2 years, and 18% (95% confidence interval, 1–53) at 3 years. No Magna/Magna Ease valves (n=12) failed by 3 years. Among valve failure patients, median age at AVR was 12 years (range, 10–21 years). Life-threatening prosthetic aortic stenosis was detected at a median of 6 months after prior echocardiograms showing mild or less gradients. Patients with Mitroflow LXA compared with Magna/Magna Ease valves were smaller (median body surface area, 1.42 versus 1.93 m2; P=0.002) and younger (median age, 13.0 versus 20.9 years; P=0.02) at AVR. Pathology demonstrated diffuse intrinsic leaflet calcification, not associated with inflammation or infection, and virtually immobile leaflets in closed position. Conclusions— Young patients undergoing AVR with Mitroflow LXA pericardial valves are at high risk for rapid progression from mild or less to severe aortic stenosis over months, highlighting their need for heightened echocardiographic surveillance and suggesting that this aortic bioprosthesis should not be implanted in the young. Current data are insufficient to assess the safety of AVR with other pericardial bioprostheses in children and the youngest adults.

Outcomes of surgery for young children with multivessel pulmonary vein stenosis

OBJECTIVE We pursued a multimodality approach to the treatment of patients with pulmonary vein stenosis, incorporating sutureless surgical repair, catheter interventions, and adjunctive chemotherapy. We report our outcomes after surgery. METHODS Between January 2007 and August 2013, 49 patients with multivessel pulmonary vein stenosis underwent operations at our institution. We retrospectively reviewed data from a pulmonary vein stenosis registry and the medical records. RESULTS At the time of the index operation, the median patient age was 6 months (range, 32 days-48 months) and weight was 4.9 kg (range, 2.1-13.4 kg). Fourteen patients (28%) died during the follow-up period (median follow-up was 0.5 years [range, 0.04-4.9 years]). There were 2 deaths (4%) within 30 days. Age at repair <6 months, weight at repair <3 kg, and a preoperative right ventricular systolic pressure < ¾ systemic were found to be associated with mortality. One patient required repeat operation for recurrent stenosis. Thirty-nine patients (80%) underwent postoperative catheterizations. The median number of catheterizations per patient was 2 (range, 0-14). Twenty-nine patients (59%) underwent catheterizations with pulmonary vein intervention. The median number of catheterizations with intervention per patient was 1 (range, 0-14). There were no identifiable associations with need for or number of catheterizations with intervention. Ten patients were listed for lung transplantation: 4 patients were de-listed, 3 patients died waiting, and 3 patients underwent transplant. CONCLUSIONS Using a multimodality approach, we observed acceptable early survival after operation in patients with pulmonary vein stenosis, despite the need for catheter reinterventions. Lung transplantation remains a viable option.

Mechanisms of tricuspid regurgitation in patients with hypoplastic left heart syndrome undergoing tricuspid valvuloplasty

OBJECTIVES Tricuspid regurgitation (TR) remains a risk factor for morbidity and mortality through staged palliation in patients with hypoplastic left heart syndrome (HLHS). Reports on the mechanisms associated with TR in patients with HLHS are limited. Thus, we sought to describe our experience with tricuspid valve (TV) repair in these patients, focusing on the mechanisms of TR and corresponding surgical techniques. METHODS We performed a retrospective single-center review (January 2000 to December 2012) of patients with HLHS undergoing TV repair and completing Fontan circulation. We evaluated the pre- and postoperative echocardiograms, intraoperative findings, and surgical techniques used. RESULTS A total of 53 TV repairs were performed in 35 patients with HLHS completing staged palliation. TV repairs were performed at stage II in 15, between stage II and III in 4, at stage III in 27, and after stage III in 7. The surgical techniques for valvuloplasty included annuloplasty (38%), anteroseptal (AS) commissuroplasty (66%), anterior papillary muscle repositioning (11%), multiple commissuroplasties (9%), septal-posterior commissuroplasty (9%), and fenestration closure (4%). The predominant jet of TR emanated along the AS commissure in 68% of the cases. All patients survived the procedure and were discharged. Preoperative echocardiography showed a dilated TV annulus on the lateral dimension, anteroposterior dimension, and area that was significantly reduced after TV repair (P < .0001). The preoperative mean TR, as assessed by lateral (P = .002) and anteroposterior (P = .005) vena contracta, was also significantly reduced after TV repair. TV repair did not significantly affect right ventricular systolic function immediately after surgery (P = .17) or at the most recent follow-up visit (P = .52). Patients with anterior leaflet prolapse were at increased risk of worse outcomes, including moderate or greater right ventricular dysfunction (P = .02). Patients requiring reoperation for TV repair were younger (6.3 vs 28.1 months, P < .0001) at the initial operation. One patient died of heart failure. Freedom from TV replacement and transplant-free survival were both 97% at the most recent follow-up point. CONCLUSIONS TR in patients with HLHS commonly emanates from the AS commissure. The associated mechanisms are often annular dilatation and anterior leaflet prolapse. Preoperative anterior leaflet prolapse was associated with worse outcomes. Annuloplasty, closure of the AS commissure, and repositioning of the anterior papillary muscle are effective in addressing TR in the short- and mid-term in this challenging population.

Takedown of cavopulmonary shunt at biventricular repair

OBJECTIVE With advances in valve repair and ventricular recruitment strategies, patients initially palliated with single ventricle physiology have been increasingly brought to biventricular circulation. Few data are available on the technical aspects and outcomes after takedown of the superior cavopulmonary anastomosis (bidirectional Glenn [BDG]). We reviewed a single-institutional experience in BDG takedown. METHODS The demographic, procedural, and outcome data were obtained for all children who had undergone BDG takedown at our institution from 2000 to 2012. The primary outcome measures were achievement of biventricular circulation, reoperation, and mortality. The secondary outcome measures were postoperative arrhythmias, superior vena cava (SVC)-right atrium (RA) or pulmonary artery stenosis at the BDG takedown site. RESULTS A total of 40 patients were included during the study period, with a mean age of 4.4 years (range, 7 months to 22 years). Primary SVC-RA anastomosis was performed in 7 patients (18%), and an anterior patch was used in 33 patients (82%). Of the 40 patients, 38 were discharged with biventricular physiology (98%) and mild or less ventricular dysfunction. During a mean follow-up period of 3.4±2.9 years, 3 patients died and 1 required heart transplantation; 2 patients developed more than mild SVC stenosis requiring reintervention and 1 developed pulmonary artery stenosis. Finally, 34 patients were in normal sinus rhythm and 4 had heart block (1 pacemaker placement). CONCLUSIONS BDG takedown can be undertaken with a low operative risk and a low incidence of SVC or pulmonary artery stenosis or sinus node dysfunction. Additional follow-up is required to see how the reconstructed SVC grows.

Histology of Pericardial Tissue Substitutes Used in Congenital Heart Surgery

Pericardium is used as a tissue substitute during pediatric heart surgery. However, little is known about the histological characteristics of pericardial tissue substitutes. We searched our clinical and Pathology databases to identify cases in which glutaraldehyde-preserved autologous pericardium, PhotoFix bovine pericardium, or Peri-Guard Repair Patch glutaraldehyde-preserved bovine pericardium was used as patch material during cardiac surgery and in which explanted tissue substitute was available for histologic examination. Tissue sections were stained with hematoxylin and eosin, Masson trichrome, and Movat pentachrome, and were graded for inflammation, tissue substitute degeneration, neointima formation, and calcification. Nonparametric statistical methods were used to test differences between groups because of small sample size. The eight patients who received PhotoFix pericardium were older (median 10 months vs 10 days, P < 0.05) and the material was in situ longer (median 14 vs 2.5 months, P < 0.05) compared to the eight who received autologous pericardium. Only three patients received glutaraldehyde-preserved bovine pericardium precluding statistical comparison. Inflammation and tissue degeneration were greater in PhotoFix pericardium compared to autologous pericardium but were no more than moderate. Neointima formation and calcification did not differ significantly between the two groups. PhotoFix bovine pericardium is associated with more inflammation and material degeneration but calcification, and neointima formation are similar to autologous pericardium. Although the short-term outcomes are acceptable, calcification and degeneration seen in some cases suggest that long-term outcomes and performance at certain anatomic locations need further study.

Outcomes after Mechanical Aortic Valve Replacement in Children and Young Adults with Congenital Heart Disease

Objectives: There are little recent data on the outcomes of mechanical aortic valve replacement (AVR) in children and young adults with congenital aortic valve disease. We sought to review the survival and associated thromboembolic or bleeding complications after mechanical AVR at a single center. Methods: Data were retrospectively collected for 121 patients undergoing prosthetic AVR from 2000 to 2014. Kaplan‐Meier estimates and Cox proportional hazards were employed. Results: Median age at AVR was 16 years (interquartile range, 12‐22.8 years). The valves implanted were the St Jude valve (St Jude Medical Inc, St Paul, Minn) in 79 patients (62%), the On‐X valve (On‐X Life Technologies Inc, Austin, Tex) in 45 patients (35%), and CarboMedics (Sorin SpA, Milan, Italy) in 3 patients (2.4%). Median valve size was 23 mm (range, 21‐25 mm). There were 5 early deaths (3.9%). Median follow‐up was 5 years (range, 1.6‐9.2 years; 600 patient‐years). There were 14 deaths during follow‐up. Survival was 90.6% ± 2.8% at 1 year, 85.4% ± 3.7% at 5 years, and 81.5% ± 4.5% at 10 years. Freedom from aortic valve reoperation was 98% ± 1.4% at 1 and 5 years, 91.5% ± 3.9% at 7 years, and 78.4% ± 6.9% at 10 years and at latest follow‐up. Univariable analysis identified younger age, lower weight, and use of a 16‐mm CarboMedics valve as predictors of reoperation. Valve sizes of 16 or 17 mm have a significantly higher risk of reoperation compared with larger valves (log‐rank test, P < .001). At multivariable analysis, only younger age was a significant independent predictor of reoperation (hazard ratio, 0.84; 95% confidence interval, 0.71‐0.99; P = .038). All patients were treated with warfarin to a goal international normalized ratio of 2.0 to 3.0. Four patients (3.1%; 0.66% per patient‐year) had thromboembolic complications, and 5 patients (3.9%; 0.83% per patient‐year) had bleeding events during follow‐up. Conclusions: Mechanical AVR in patients with congenital heart disease has excellent short‐ and midterm outcomes. Younger age was an independent predictor of reoperation.

Photo-oxidized bovine pericardium in congenital cardiac surgery: single-centre experience.

Objectives Dye-mediated photo-oxidation of pericardium is an alternative method to chemical treatment with glutaraldehyde for cross-linking collagen, providing biostability of the patch material while avoiding late calcification and cytotoxicity. There are few data available, on using photo-oxidation-treated pericardium, in congenital cardiac surgery. This study reports the outcomes using Photofix™ bovine pericardium in neonates, infants, children and young adults undergoing paediatric cardiac surgery. Methods A total of 490 patches in 383 consecutive operations (364 patients) were used in the surgical repair of congenital heart defects at our institution from October 2008 to October 2011. Recorded variables included demographic data, age at operation, primary cardiac diagnosis, associated complications and number, type and location of patches placed and patch-related reintervention. Results Median age at operation was 5.3 years, ranging from <1 month to 56 years. The overall survival rate at late follow-up was 92%, and no deaths were related to failure of the tissue substitute. Two patients (0.5%) underwent reintervention late due to patch material failure: one for residual shunt after Rastelli repair and one for aneurysmal dilatation of a right ventricular outflow tract patch. The patch material was explanted in 8 patients at a mean of 20 months (range, 1-72 months) following implantation. Histological examination revealed mild to moderate inflammation with variable calcification. Conclusions Photo-oxidized bovine pericardium demonstrated excellent performance when used as a patch material in cardiovascular repair in children. Its handling characteristics and biocompatibility are consistent with a wide range of applications.

Pathology of Valved Venous Homografts Used As Right Ventricle To Pulmonary Artery Conduits in Congenital Heart Disease Surgery

Objectives: Although valved venous homografts (VVHs) are used for establishing right ventricle‐to‐pulmonary artery continuity in some complex heart defects, the tissue changes that occur in situ have not been described. We review the gross and microscopic changes observed in explanted VVH conduits and their effects on functionality. Methods: In total, 20 explanted VVH conduits were evaluated for valve integrity, presence of thrombus, and stenosis. Hematoxylin and eosin– and trichrome‐stained sections were reviewed for neointima formation, wall remodeling, inflammation, and calcification. Regurgitation and narrowing were assessed on pre‐explant echocardiogram, and angiographic video clips were correlated with tissue findings. The source of the proliferating cells within the conduits was investigated by fluorescent in situ hybridization. Results: Thirteen male and 7 female infants underwent VVH implantation either as part of a composite Sano shunt (65%) or to establish right ventricle‐to‐pulmonary artery continuity in biventricular hearts (35%). The median duration of conduits in situ was 140 days (range: 98‐340 days). Conduits were predominantly explanted for staged conversion to bidirectional Glenn (60%) and conduit upsizing (20%). The valves remained intact and functional in 75% of cases. Occlusive thrombosis was absent in all. Wall thickening due to neointima formation and wall remodeling was uniformly present and appeared to be driven by smooth muscle actin–expressing cells, which by fluorescent in situ hybridization are predominantly of recipient origin. Minimal calcification and mild adventitial chronic inflammation were present. Conclusions: Vein wall thickening is a uniform finding and can cause stenosis. The valves remain functional in most, and vein walls undergo remodeling with only minimal inflammation and calcification.

Augmentation of Bridging Leaflets in Repair of Atrioventricular Canal Defects

Left atrioventricular (AV) valve regurgitation is the most common complication after a atrioventricular canal defect (AVCD) repair. Despite what appears to be a less complex repair, patients with partial and transitional AV canal have higher reoperation rates for left AV valve regurgitation and left ventricular outflow tract (LVOT) obstruction. Retraction of bridging leaflets with secondary attachments to the septal crest commonly produces increased tension and flattening of the medial left AV valve leaflet and LVOT obstruction after cleft closure. We describe a novel technique of detachment and patch augmentation of bridging leaflets to avoid these complications.

Outcomes and Short-Term Follow-Up in Complex Ross Operations in Pediatric Patients Undergoing Damus-Kaye-Stansel Takedown

Review echocardiography and outcomes before and after Ross procedures, including patients undergoing biventricular conversion with Damus-Kaye-Stansel (DKS) takedown. A retrospective review was performed on 62 patients undergoing simple (control group) and complex Ross procedures, including 12 patients who underwent biventricular conversion with Ross operation and DKS takedown (complex). Echocardiography was reviewed preoperatively and at discharge and late follow-up. Kaplan-Meier estimates of patient survival and freedom from reintervention were obtained. In all, 62 patients had a median age of 4.5 years (interquartile range [IQR]: 1-12.5), weight of 16.4kg (IQR: 8-41), and follow-up of 3.8 years (IQR: 1.3-6). The complex DKS takedown group had 2 deaths, no neoaortic valve or root reinterventions, and 3 right ventricular outflow tract (VOT) reinterventions. There were no differences from the control group in left VOT or right VOT reinterventions. Neither group showed differences between pre- and late follow-up aortic root and ascending aorta dimensions, and no correlations were found among preoperative pulmonary valve (PV) size, late aortic regurgitation (AR), aortic root, or ascending aortic Z-scores. Aortic valve size increased from discharge to late follow-up for both groups (P ≤ .05); 90% of patients at late follow-up had mild or less AR with similar distributions in severity between complex and control groups. Severity of late AR showed no correlation with preoperative PV size and is independent of it. The Ross procedure has good short-term results in simple and complex patients and should be considered in those undergoing Ross operation with biventricular conversion and DKS takedown. Moreover, native PV size should not be a contraindication for Ross procedure.