title: The use of a high-power laser on swine mitral valve chordae tendineae.
abstract: Worldwide, rheumatic fever remains a significant cause of mitral valve insufficiency. It is responsible for approximately 90 % of early childhood valvular surgeries in Brazil. Elongated or flail chordae are frequently responsible and require surgical correction. The purpose of this study was to analyze and compare the histological tissues of the mitral valve chordae and the mechanical resistance generated by the chordae, both with and without the application of a high-power laser. Twenty normal porcine mitral valve chordae were measured and divided randomly into the following two groups: control group (not subjected to a high-power laser) and laser group (subjected to photonic irradiation). Laser surgery was performed under controlled conditions, using following parameters: λ = 980-nm wavelength, power = 3 W, and energy = 60 J. A mechanical test machine was used in combination with a subsequent histological study to measure chordae tensile properties. A histological analysis demonstrated a typical collagen bundle arrangement in the control group; however, under a particular reached temperature range (48), the collagen bundles assumed different arrangements in the laser group. Significant reductions in the chordae tendineae lengths and changes in their resistance in the laser group were observed, as these chordae exhibited less rigid fibers. The chordae tendineae of normal porcine valves subjected to a high-power laser exhibited its length reduction and less stiffness compared to the control group. A histological analysis of the laser treatment specimens demonstrated differences in collagen bundle spatial organization, following slight changes into tissue temperature.
authors.affiliation: Cardiovascular and Thoracic Surgery Department of The Heart Institute - General Hospital, Medical School, University of São Paulo, 44, Dr. Enéas de Carvalho Aguiar Avenue, 2nd floor, 05403-900, São Paulo, SP, Brazil. nathalicordeiro@hotmail.com.|Valvar Surgery Department of Heart Institute - Clinical Hospital, Medical School, University of São Paulo, 44, Av.Dr. Eneas de Carvalho Aguiar, 2nd floor, 05403-900, São Paulo, SP, Brazil. nathalicordeiro@hotmail.com.
authors.forename: Nathali Cordeiro
authors.initials: NC
authors.lastname: Pinto
authors.affiliation: Cardiovascular and Thoracic Surgery Department of The Heart Institute - General Hospital, Medical School, University of São Paulo, 44, Dr. Enéas de Carvalho Aguiar Avenue, 2nd floor, 05403-900, São Paulo, SP, Brazil.|Post Graduate Program in Biophotonics and Medicine, University Nove de Julho, 235, Vergueiro, 01504-001, São Paulo, SP, Brazil.
authors.forename: M Cristina
authors.initials: MC
authors.lastname: Chavantes
authors.affiliation: Nuclear and Energy Research Institute/Center for Lasers and Applications-IPEN/CLA, University of São Paulo, 2242, Professor Lineu Prestes Avenue, 05508-900, São Paulo, SP, Brazil.
authors.forename: Denise
authors.initials: D
authors.lastname: Zezell
authors.affiliation: Post Graduate Program in Biophotonics and Medicine, University Nove de Julho, 235, Vergueiro, 01504-001, São Paulo, SP, Brazil.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Deana
authors.affiliation: Nuclear and Energy Research Institute/Center for Lasers and Applications-IPEN/CLA, University of São Paulo, 2242, Professor Lineu Prestes Avenue, 05508-900, São Paulo, SP, Brazil.
authors.forename: Carolina
authors.initials: C
authors.lastname: Benetti
authors.affiliation: Post Graduate Program in Biophotonics and Medicine, University Nove de Julho, 235, Vergueiro, 01504-001, São Paulo, SP, Brazil.
authors.forename: Rodrigo Labat
authors.initials: RL
authors.lastname: Marcos
authors.affiliation: Research and Education Center for Phototherapy in Health Sciences, 831, Sebastião Moraes, 13562-030, São Carlos, SP, Brazil.
authors.forename: Luciana Almeida
authors.initials: LA
authors.lastname: Lopes
authors.affiliation: Institute of Biomedical Sciences - ICB, University of São Paulo, 2415, Professor Lineu Prestes Avenue, Cidade Universitária, 05508-900, São Paulo, SP, Brazil.
authors.forename: Rodrigo A B Lopes
authors.initials: RA
authors.lastname: Martins
authors.affiliation: Pathology Department of Heart Institute - Clinical Hospital, Medical School, University of São Paulo, 44, Dr. Enéas de Carvalho Aguiar Avenue, SS floor, 05403-900, São Paulo, SP, Brazil.
authors.forename: Vera Demarchi
authors.initials: VD
authors.lastname: Aiello
authors.affiliation: Cardiovascular and Thoracic Surgery Department of The Heart Institute - General Hospital, Medical School, University of São Paulo, 44, Dr. Enéas de Carvalho Aguiar Avenue, 2nd floor, 05403-900, São Paulo, SP, Brazil.
authors.forename: Fabio Biscegli
authors.initials: FB
authors.lastname: Jatene
authors.affiliation: Cardiovascular and Thoracic Surgery Department of The Heart Institute - General Hospital, Medical School, University of São Paulo, 44, Dr. Enéas de Carvalho Aguiar Avenue, 2nd floor, 05403-900, São Paulo, SP, Brazil.|Valvar Surgery Department of Heart Institute - Clinical Hospital, Medical School, University of São Paulo, 44, Av.Dr. Eneas de Carvalho Aguiar, 2nd floor, 05403-900, São Paulo, SP, Brazil.
authors.forename: Pablo M A
authors.initials: PM
authors.lastname: Pomerantzeff
mesh_terms: D000818:Animals; D002815:Chordae Tendineae / Q000601:surgery*; D003094:Collagen; D006349:Heart Valve Diseases / Q000601:surgery*; D053685:Laser Therapy / Q000379:methods*; D008027:Light; D008943:Mitral Valve; D013552:Swine; D013696:Temperature
chemical_list: D003094:Collagen
keywords: Chordae tendineae; High-power laser; Mitral valve; Mitral valve repair; Rheumatic disease