Desp ite the otolary ngo logist 's most diligent elfo rts to pre vent it, hem orrh age is the most comtnon, albei t sporadic, significant complication oftons illectomy. For this retrospective study of post-tonsillecto my hemorrhage rates, we exainined the charts of 430 consec utive tons illectonty patients who had been op erated on by one oftwo ge neral otolaryn gologists at our institution. The two surgeons used the satn e removal technique (cold diss ection and snare), but slightly different methods of hemostasis. We fo und that the ove rall bleedin g rate was 4%; the primary «24 hr) hetnorrhage rate was 0.23 %, and the seco ndary rate was 3.7%. Factors that we re positively correlated with postoperative bleedin g we re the patient 's sex, the time ofyear the surgery was perfo rmed, the length ofthe pro cedu re, the ainount ofblood lost du ring surg ery , and the use of intraoperative vasocon strictors and steroids. How ever. we believe the use of steroids can probab ly be discounted as a causative fa cto r. The X 2 test was used to determine statistical sig nificance. None ofthe 21 patients who we re ope rated on for pe ritons illa r abscess exp eri enced any delayed postoperative bleeding. The tnean decrease in hemoglobin was 2.3 gram s; the lowest postoperative level was 6.6 grams. The highest incidenee of delayed bleeding occurred on the eighth postoperative day. Two patients required tra nsfusions, and bo th recov ered without any adverse consequenc es. It app ears that on e controllable variab le in pre ventin g delayed bleedin g followin g tonsillectoniy and ad enoidectomy might be related to certain details of hemo static techn ique. Vasoconstrictors and "field'' cauterizatio n might be associated with an increased temporai and spatia l app lication ofcoag ulating current. Although this technique is very elfective in preventing primary hemorrhage, it do es resu lt in a deeper and tnore ex tensive zone of necrosis and the exposure of more and larger vess els when slou ghing of the eschar occ urs.

Background— Valvular endothelial cells and circulating endothelial progenitor cells (EPCs) can undergo apparent phenotypic change from endothelial to mesenchymal cell type. Here we investigated whether EPCs can promote extracellular matrix formation in tissue engineering scaffolds in response to transforming growth factor (TGF)-β1. Method and Results— Characterized ovine peripheral blood EPCs were seeded onto poly (glycolic acid)/poly (4-hydroxybutyrate) scaffolds for 5 days. After seeding at 2×10 6 cells/cm 2 , scaffolds were incubated for 5 days in a roller bottle, with or without the addition of TGF-β1. After seeding at 15×10 6 cells/cm 2 , scaffolds were incubated for 10 days in a roller bottle with or without the addition of TGF-β1 for the first 5 days. Using immunofluorescence and Western blotting, we demonstrated that EPCs initially exhibit an endothelial phenotype (ie, CD31 + , von Willebrand factor + , and α–smooth muscle actin (SMA) − ) and can undergo a phenotypic change toward mesenchymal transformation (ie, CD31 + and α-SMA + ) in response to TGF-β1. Scanning electron microscopy and histology revealed enhanced tissue formation in EPC-TGF-β1 scaffolds. In both the 10- and 15-day experiments, EPC-TGF-β1 scaffolds exhibited a trend of increased DNA content compared with unstimulated EPC scaffolds. TGF-β1–mediated endothelial to mesenchymal transformation correlated with enhanced expression of laminin and fibronectin within scaffolds evidenced by Western blotting. Strong expression of tropoelastin was observed in response to TGF-β1 equal to that in the unstimulated EPC. In the 15-day experiments, TGF-β1–stimulated scaffolds revealed dramatically enhanced collagen production (types I and III) and incorporated more 5-bromodeoxyuridine and TUNEL staining compared with unstimulated controls. Conclusions— Stimulation of EPC-seeded tissue engineering scaffolds with TGF-β1 in vitro resulted in a more organized cellular architecture with glycoprotein, collagen, and elastin synthesis, and thus noninvasively isolated EPCs coupled with the pleiotropic actions of TGF-β1 could offer new strategies to guide tissue formation in engineered cardiac valves.

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.

Heart valve disease is a significant medical problem worldwide. Current treatment for heart valve disease is heart valve replacement. State of the art replacement heart valves are less than ideal and are associated with significant complications. Using the basic principles of tissue engineering, promising alternatives to current replacement heart valves are being developed. Significant progress has been made in the development of a tissue-engineered semilunar heart valve substitute. Advancements include the development of different potential cell sources and cell-seeding techniques; advancements in matrix and scaffold development and in polymer chemistry fabrication; and the development of a variety of bioreactors, which are biomimetic devices used to modulate the development of tissue-engineered neotissue in vitro through the application of biochemical and biomechanical stimuli. This review addresses the need for a tissue-engineered alternative to the current heart valve replacement options. The basics of heart valve structure and function, heart valve disease, and currently available heart valve replacements are discussed. The last 10 years of investigation into a tissue-engineered heart valve as well as current developments are reviewed. Finally, the early clinical applications of cardiovascular tissue engineering are presented.