RESUMO
A 58-year-old male patient was admitted with chest pain and was diagnosed with coronary heart disease. He was scheduled for coronary artery bypass grafting (CABG) under cardiopulmonary bypass (CPB). Intraoperative real-time transesophageal echocardiography (TEE) showed that the tricuspid valves were well-aligned and subtle regurgitation. Real-time TEE after separation from CPB showed severe tricuspid regurgitation and prolapsed chordae tendineae. The tricuspid chordae tendineae rupture due to a right atrial venous return cannula. The use of negative pressure to improve venous drainage during CPB may result in the tricuspid valve being adsorbed to the cannula, increasing the likelihood of injury to the tricuspid valve.
Assuntos
Ruptura Cardíaca , Doenças das Valvas Cardíacas , Insuficiência da Valva Tricúspide , Masculino , Humanos , Pessoa de Meia-Idade , Insuficiência da Valva Tricúspide/complicações , Insuficiência da Valva Tricúspide/diagnóstico por imagem , Insuficiência da Valva Tricúspide/cirurgia , Ecocardiografia , Valva Tricúspide/diagnóstico por imagem , Valva Tricúspide/cirurgia , Ruptura , Cordas Tendinosas/diagnóstico por imagem , Cordas Tendinosas/cirurgia , Cordas Tendinosas/lesões , Ponte de Artéria Coronária/efeitos adversosRESUMO
BACKGROUND: The World Symposium of Pulmonary Hypertension in 2018, updated the definition of pulmonary hypertension (PH) as mean pulmonary artery pressures (PAP) > 20 mmHg. Pulmonary venous hypertension secondary to left-heart disease, constitutes the most common cause of PH, and the determination of a co-existent pre-capillary (primary) PH becomes paramount, particularly at the moment of evaluating and managing patients with heart failure. Pulmonary artery pressures above the systemic pressures define supra-systemic PH and generally leads to frank right ventricular failure and high mortality. CASE PRESENTATION: We present the perioperative management of a patient with rheumatic mitral valve disease, initially found to have severe PH due to pulmonary venous hypertension, who underwent percutaneous mitral balloon valvuloplasty complicated with mitral chordae rupture, severe mitral regurgitation and supra-systemic PH. Multiple medical therapies and an intra-aortic balloon pump were used as means of non-surgical management of this complication. CONCLUSIONS: This case report illustrates the perioperative implications of combined pre- and post-capillary PH and supra-systemic PH, as this has not been widely discussed in previous literature. A thorough literature review of the clinical characteristics of PH, methods to determine co-existent pre- and post-capillary PH components, as well as concomitant right ventricular failure is presented. Severe PH has known detrimental effects on the hemodynamic status of patients, which can ultimately lead to a decrease in effective cardiac output and poor tissue perfusion.
Assuntos
Valvuloplastia com Balão , Hipertensão Pulmonar/terapia , Estenose da Valva Mitral/terapia , Cordas Tendinosas/lesões , Feminino , Humanos , Balão Intra-Aórtico , Pessoa de Meia-Idade , Insuficiência da Valva Mitral/terapia , Pirimidinas/uso terapêutico , Cardiopatia Reumática/complicações , Cardiopatia Reumática/terapia , Ruptura Espontânea , Sulfonamidas/uso terapêutico , Vasodilatadores/uso terapêuticoAssuntos
Forame Oval Patente/diagnóstico por imagem , Comunicação Interatrial/diagnóstico por imagem , Insuficiência da Valva Mitral/diagnóstico por imagem , Prolapso da Valva Mitral/diagnóstico por imagem , Cordas Tendinosas/diagnóstico por imagem , Cordas Tendinosas/lesões , Ecocardiografia , Feminino , Forame Oval Patente/complicações , Forame Oval Patente/fisiopatologia , Comunicação Interatrial/fisiopatologia , Humanos , Pessoa de Meia-Idade , Insuficiência da Valva Mitral/etiologia , Prolapso da Valva Mitral/complicações , Ruptura/diagnóstico por imagemAssuntos
Bioprótese , Cordas Tendinosas/cirurgia , Matriz Extracelular/transplante , Traumatismos Cardíacos/cirurgia , Implante de Prótese de Valva Cardíaca/instrumentação , Próteses Valvulares Cardíacas , Insuficiência da Valva Tricúspide/cirurgia , Valva Tricúspide/cirurgia , Cordas Tendinosas/diagnóstico por imagem , Cordas Tendinosas/lesões , Cordas Tendinosas/fisiopatologia , Traumatismos Cardíacos/diagnóstico por imagem , Traumatismos Cardíacos/etiologia , Traumatismos Cardíacos/fisiopatologia , Humanos , Pessoa de Meia-Idade , Desenho de Prótese , Recuperação de Função Fisiológica , Resultado do Tratamento , Valva Tricúspide/diagnóstico por imagem , Valva Tricúspide/lesões , Valva Tricúspide/fisiopatologia , Insuficiência da Valva Tricúspide/diagnóstico por imagem , Insuficiência da Valva Tricúspide/etiologia , Insuficiência da Valva Tricúspide/fisiopatologiaRESUMO
BACKGROUND: Papillary muscle rupture in the perinatal period is a rare event that leads to severe mitral or tricuspid insufficiency due to a flail leaflet. Neonatal tricuspid chordal reconstruction for this condition is rarely reported. Early recognition and treatment have the potential to be lifesaving. We present our surgical experience with five such patients, along with their midterm follow-up. METHODS: Between August 2010 and November 2012, five neonates (aged 1-30 days) underwent surgery for severe atrioventricular valve regurgitation. All neonates had severe tricuspid regurgitation due to ruptured chordae. In addition, two had moderate mitral regurgitation; one due to ruptured chordae of the posterior mitral leaflet and the other due to prolapse of the anterior mitral leaflet. All underwent emergent surgery where the ruptured chordae to the anterior tricuspid leaflet were replaced with neochordae made with expanded polytetrafluoroethylene (ePTFE) suture. The mitral valve was repaired in two patients. RESULTS: All patients survived surgery without the need for postoperative mechanical circulatory assist. Predischarge echocardiograms showed good coaptation of tricuspid and mitral leaflets with minimal regurgitation in all. At follow-up between 75 months to 102 months, four patients had excellent outcomes with less than mild tricuspid regurgitation. One child with flail tricuspid and mitral leaflets developed progressive tricuspid and mitral regurgitation requiring surgical re-repair at 20 months following the initial surgery. CONCLUSION: Repair of chordal rupture of the tricuspid valve in neonates using ePTFE neo-chordae can provide acute salvage and gratifying midterm results in the management of this potentially fatal condition.
Assuntos
Cordas Tendinosas/lesões , Insuficiência da Valva Tricúspide/etiologia , Valva Tricúspide/cirurgia , Cordas Tendinosas/diagnóstico por imagem , Cordas Tendinosas/cirurgia , Ecocardiografia , Feminino , Seguimentos , Ruptura Cardíaca/complicações , Humanos , Recém-Nascido , Masculino , Gravidez , Ruptura , Fatores de Tempo , Valva Tricúspide/diagnóstico por imagem , Insuficiência da Valva Tricúspide/diagnóstico , Insuficiência da Valva Tricúspide/cirurgiaRESUMO
Emery Dreifuss muscular dystrophy (EDMD) is an inherited myopathy characterized by early contractures, slow progressive muscle weakness and cardiac involvement. To date at least seven genes have been associated to EDMD with different inheritance patterns, being emerin gene responsible for the X-linked form of the disease. We report a 40-year-old man who was referred for severe gait difficulty. At age 6 years the patient presented with a waddling gate, lumbar lordosis and heel contractures. Both electrophysiology and muscle biopsy were consistent with a neurogenic disorder and he received a diagnosis of spinal muscular atrophy type 3. At the age of 30 the patient developed heart involvement with junctional escape rhythm and, eight years later, had a spontaneous chordae tendinae rupture. A new clinical examination showed severe muscular weakness and atrophy in scapulohumeroperoneal pattern with significant involvement of the lower facial and intrinsic hand muscles and on a second muscle biopsy emerin was absent by immunohistochemistry and by immunoblot analysis. Sequence analysis of EMD gene revealed the presence of a novel mutation represented by an out-of-frame deletion spanning from the beginning of exon 1 to the half of intron 2 (p.Asp6Glyfs*27). Our study expands the clinical and molecular spectrum of X-linked EDMD.
Assuntos
Cordas Tendinosas/lesões , Proteínas de Membrana/genética , Distrofia Muscular de Emery-Dreifuss/genética , Mutação/genética , Proteínas Nucleares/genética , Ruptura Espontânea/genética , Adulto , Cordas Tendinosas/diagnóstico por imagem , Eletrocardiografia/métodos , Humanos , Masculino , Distrofia Muscular de Emery-Dreifuss/complicações , Distrofia Muscular de Emery-Dreifuss/diagnóstico por imagem , Linhagem , Ruptura Espontânea/complicações , Ruptura Espontânea/diagnóstico por imagemRESUMO
PURPOSE: Chordae rupture is one of the main lesions observed in traumatic heart events that might lead to severe tricuspid valve (TV) regurgitation. TV regurgitation following chordae rupture is often well tolerated with few or no symptoms for most patients. However, early repair of the TV is of great importance, as it might prevent further exacerbation of the regurgitation due to remodeling responses. To understand how TV regurgitation develops following this acute event, we investigated the changes on TV geometry, mechanics, and function of ex-vivo porcine hearts following chordae rupture. METHODS: Sonomicrometry techniques were employed in an ex-vivo heart apparatus to identify how the annulus geometry alters throughout the cardiac cycle after chordae rupture, leading to the development of TV regurgitation. RESULTS: We observed that the TV annulus significantly dilated (~9% in area) immediately after chordae rupture. The annulus area and circumference ranged from 11.4 ± 2.8 to 13.3 ± 2.9 cm2 and from 12.5 ± 1.5 to 13.5 ± 1.3 cm, respectively, during the cardiac cycle for the intact heart. After chordae rupture, the annulus area and circumference were larger and ranged from 12.3 ± 3.0 to 14.4 ± 2.9 cm2 and from 13.0 ± 1.5 to 14.0 ± 1.2 cm, respectively. CONCLUSIONS: In our ex-vivo study, we showed for the first time that the TV annulus dilates immediately after chordae rupture. Consequently, secondary TV regurgitation may be developed because of such changes in the annulus geometry. In addition, the TV leaflet and the right ventricle myocardium are subjected to a different mechanical environment, potentially causing further negative remodeling responses and exacerbating the detrimental outcomes of chordae rupture.
Assuntos
Cordas Tendinosas/lesões , Traumatismos Cardíacos/patologia , Insuficiência da Valva Tricúspide/etiologia , Insuficiência da Valva Tricúspide/cirurgia , Valva Tricúspide/lesões , Animais , Fenômenos Biomecânicos , Cordas Tendinosas/fisiopatologia , Cordas Tendinosas/cirurgia , Dilatação , Modelos Animais de Doenças , Traumatismos Cardíacos/fisiopatologia , Traumatismos Cardíacos/cirurgia , Hemodinâmica , Técnicas In Vitro , Modelos Cardiovasculares , Sus scrofa , Valva Tricúspide/fisiopatologia , Valva Tricúspide/cirurgia , Insuficiência da Valva Tricúspide/fisiopatologiaRESUMO
BACKGROUND: Today, there is no manufacturer-supplied retrieval tool for the Micra™ pacemaker (Medtronic, Minneapolis, MN, USA); therefore, off-the-shelf catheters have been employed for retrievals. The proximal retrieval feature of the Micra™ can be snared and the device is then retracted from the myocardium, pulling the device through the tricuspid valve. This study characterizes the potential risks of Micra™ nitinol tine engagement with the tricuspid sub-valvular apparatus. METHODS: Fresh human hearts nonviable for transplant (n = 10) were obtained from our regional organ procurement agency (LifeSource, Minneapolis, MN, USA). Micra™ fixation tines were affixed to a linear force transducer. Tines were then engaged in tricuspid chordae tendineae to conduct a constant velocity tensile test. Each test was run until tines disengaged from the chordae tendineae or until they released from the valve apparatus. Subsequently, biomechanical failure properties of the valve apparatus and isolated chordae tendineae were determined using a series of uniaxial tensile tests. RESULTS: There were no chordal ruptures observed during our Micra™ tine extraction testing. Chordal failure required 15.0 times the force of extracting a single engaged tine, and 9.0 times the force of extracting two engaged tines. The uniaxial stresses required for isolated chordal failure averaged 17.4 N/mm2 ; failure strains exceeded 150% resting chordal length. CONCLUSIONS: The forces required to rupture tricuspid chordae tendineae significantly exceeded the forces potentially imposed on the chordae during Micra™ device retrievals. We conclude that the fixation tines of the Micra™ device are unlikely to damage the tricuspid apparatus during either implant or retrieval.
Assuntos
Remoção de Dispositivo , Marca-Passo Artificial , Ligas , Cordas Tendinosas/lesões , Desenho de Equipamento , Humanos , Técnicas In Vitro , Valva Tricúspide/lesõesRESUMO
An 86-year-old man was admitted our hospital because of sudden onset of dyspnea after blunt chest trauma. Because his oxygen saturation deteriorated from 92% in the supine position to 86% in the sitting position, platypnea-orthodeoxia syndrome was suspected. Transesophageal echocardiography showed severe tricuspid regurgitation (TR) caused by anterior papillary muscle rupture. Furthermore, right-to-left shunt with TR through a patent foramen ovale (PFO) was observed. The diagnosis was therefore platypnea-orthodeoxia syndrome with right-to-left shunt through PFO with shunting exacerbated by acute severe TR after blunt chest trauma. The patient underwent urgent tricuspid valve repair and PFO closure and has remained asymptomatic postoperatively.
Assuntos
Cordas Tendinosas/lesões , Dispneia/etiologia , Traumatismos Cardíacos/complicações , Traumatismos Torácicos/complicações , Insuficiência da Valva Tricúspide/complicações , Ferimentos não Penetrantes/complicações , Idoso de 80 Anos ou mais , Cateterismo Cardíaco , Procedimentos Cirúrgicos Cardíacos/métodos , Cordas Tendinosas/diagnóstico por imagem , Ecocardiografia Transesofagiana , Traumatismos Cardíacos/diagnóstico , Traumatismos Cardíacos/cirurgia , Humanos , Masculino , Traumatismos Torácicos/diagnóstico , Insuficiência da Valva Tricúspide/diagnóstico , Insuficiência da Valva Tricúspide/cirurgia , Ferimentos não Penetrantes/diagnósticoAssuntos
Cordas Tendinosas , Traumatismos Torácicos/complicações , Valva Tricúspide , Ferimentos não Penetrantes/complicações , Adulto , Cordas Tendinosas/diagnóstico por imagem , Cordas Tendinosas/lesões , Ecocardiografia , Humanos , Imageamento Tridimensional , Masculino , Ruptura/diagnóstico por imagem , Valva Tricúspide/diagnóstico por imagem , Valva Tricúspide/lesões , Adulto JovemRESUMO
A 40-year-old man was transferred to our hospital following an isolated horse kick injury to the anterior chest wall. The case showed bi-fascicular block, severe tricuspid valve regurgitation due to ruptured chordae tendineae of the anterior leaflet, moderate mitral valve regurgitation due to prolapse of mitral anterior leaflet, and hypokinetic motion of the inferior septal wall. Both tricuspid and mitral insufficiency were completely repaired by a surgical operation. Fortunately, these injuries were not fatal in this case, but the comprehensive assessment of cardiac damage and careful observation are important for managing patients with cardiac injury.
Assuntos
Bloqueio de Ramo/etiologia , Cordas Tendinosas/lesões , Traumatismos Cardíacos/etiologia , Insuficiência da Valva Mitral/etiologia , Insuficiência da Valva Tricúspide/etiologia , Adulto , Animais , Bloqueio de Ramo/diagnóstico , Bloqueio de Ramo/cirurgia , Traumatismos Cardíacos/diagnóstico , Traumatismos Cardíacos/terapia , Cavalos , Humanos , Masculino , Insuficiência da Valva Mitral/diagnóstico , Insuficiência da Valva Mitral/cirurgia , Insuficiência da Valva Tricúspide/diagnóstico , Insuficiência da Valva Tricúspide/cirurgiaAssuntos
Endocardite/etiologia , Infecções Estreptocócicas/complicações , Cordas Tendinosas/lesões , Cordas Tendinosas/microbiologia , Dispneia/etiologia , Ecocardiografia/métodos , Serviço Hospitalar de Emergência/organização & administração , Feminino , Febre/etiologia , Humanos , Itália , Pessoa de Meia-Idade , Valva Mitral/microbiologia , Valva Mitral/fisiopatologia , Streptococcus agalactiae/patogenicidadeRESUMO
Blunt chest trauma can cause not only damage to the thoracic cage, but can also injure intracardiac structures including the papillary muscles, chordae tendineae, and valve leaflets. Aortic valve (AV) injury secondary to blunt chest trauma is a rare occurrence. Clinically, AV injury may be missed during the initial post-trauma assessment due to the lack of suspicion of cardiac involvement. Thus, the diagnosis of AV injury is often delayed or missed for a time interval of days to months. As a consequence, the traumatic AV regurgitation can rapidly or progressively lead to congestive heart failure unless surgically corrected. Therefore, emergency physicians should be aware of the possibility of intracardiac structure injury, such as valvular injuries, after blunt chest trauma. Guidelines for the appropriate use of bedside cardiac ultrasound (BCU) recommend BCU should be performed in all patients with new murmurs for clinically significant valvular lesions that could potentially change management. We described the case of a 73-year-old female patient with AV injury after blunt trauma. She experienced cardiac arrest (CA) secondary to a moderate-to-severe traumatic AR, which was successfully treated with emergency AV replacement. We discuss how to diagnose and manage a CA patient, aided by BCU, with ventricular failure associated with persistent AV regurgitation. To the best of our knowledge, this is the first case report on CA associated with isolated rupture of bicuspid AV rupture and AV regurgitation secondary to blunt chest trauma because of the lack of early suspicion of AV injury.
Assuntos
Insuficiência da Valva Aórtica/complicações , Cordas Tendinosas/lesões , Parada Cardíaca/etiologia , Traumatismos Cardíacos/complicações , Ferimentos não Penetrantes/complicações , Idoso , Insuficiência da Valva Aórtica/diagnóstico , Cordas Tendinosas/diagnóstico por imagem , Ecocardiografia Doppler em Cores , Feminino , Traumatismos Cardíacos/diagnóstico , Humanos , Ruptura , Tomografia Computadorizada por Raios X , Ferimentos não Penetrantes/diagnósticoRESUMO
Myocardial contusion and aortic injury are well-known cardiac complications of blunt chest trauma, but valvular injury is rare. Traumatic valve injuries most commonly involve the aortic valve, with isolated mitral valve injury being quite rare. We report a case of acute severe mitral regurgitation due to ruptured chordae tendineae requiring surgical repair following a motor vehicle accident.
Assuntos
Cordas Tendinosas/diagnóstico por imagem , Cordas Tendinosas/lesões , Ecocardiografia/métodos , Ruptura Cardíaca/diagnóstico por imagem , Insuficiência da Valva Mitral/diagnóstico por imagem , Traumatismos Torácicos/diagnóstico por imagem , Ferimentos não Penetrantes/complicações , Acidentes de Trânsito , Doença Aguda , Idoso , Cordas Tendinosas/cirurgia , Feminino , Ruptura Cardíaca/etiologia , Ruptura Cardíaca/cirurgia , Humanos , Insuficiência da Valva Mitral/etiologia , Insuficiência da Valva Mitral/cirurgia , Traumatismos Torácicos/complicações , Traumatismos Torácicos/cirurgia , Ferimentos não Penetrantes/diagnóstico por imagem , Ferimentos não Penetrantes/cirurgiaRESUMO
Traumatic tricuspid regurgitation is a rare and progressive disease. Early diagnosis and surgical valve repair are very important. A 57-year-old male was referred to our hospital with a history of blunt chest trauma. Three-dimensional echocardiography showed severe tricuspid regurgitation and demonstrated two main anterior leaflet chordaes of the tricuspid valve rupture and the whole anterior leaflet prolapsed. The diagnosis was severe tricuspid regurgitation due to leaflet chordae rupture secondary to blunt chest trauma. Surgical repair of the tricuspid valve was performed in this patient. At 3-month follow-up, the right ventricle was decreased in size with significantly improved right ventricular function. The signs and symptoms of right heart failure were relieved. In this case, 3-dimensional transthoracic echocardiography enabled fast and non-invasive evaluation of the spatial destruction of the tricuspid valve and subvalvular apparatus to assist in the planning of valve repair.
Assuntos
Traumatismos Torácicos/complicações , Insuficiência da Valva Tricúspide/etiologia , Ferimentos não Penetrantes/complicações , Procedimentos Cirúrgicos Cardíacos/métodos , Cordas Tendinosas/diagnóstico por imagem , Cordas Tendinosas/lesões , Cordas Tendinosas/cirurgia , Ecocardiografia , Ecocardiografia Doppler em Cores , Ecocardiografia Tridimensional , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Traumatismos Torácicos/diagnóstico , Valva Tricúspide/diagnóstico por imagem , Valva Tricúspide/lesões , Valva Tricúspide/cirurgia , Insuficiência da Valva Tricúspide/diagnóstico , Insuficiência da Valva Tricúspide/cirurgia , Ferimentos não Penetrantes/diagnósticoRESUMO
Resumen Se presenta el caso de un adulto con insuficiencia de la válvula tricúspide de origen traumático, debido a ruptura del músculo papilar de la valva anterior en relación a trauma de tórax cerrado, se realizó el diagnóstico mediante ecocardiografía transesofágica. La válvula se reemplazó mediante bioprótesis con resultados clínicos favorables. Este caso enfatiza la necesidad de una alta sospecha de lesión valvular por parte del clínico en los pacientes con trauma torácico cerrado. (Acta Med Colomb 2016; 41: 202-205).
Abstract The case of an adult with traumatic tricuspid valve insufficiency due to papillary muscle rupture of the anterior leaflet in relation to closed chest trauma is presented. Diagnosis was made by trans-esophageal echocardiography. The valve was replaceded by bioprosthesis with favorable clinical outcome. This case emphasizes the need for a high suspicion of valvular lesion by the clinician in patients with blunt chest trauma. (Acta Med Colomb 2016; 41: 202-205).
Assuntos
Humanos , Masculino , Adulto , Insuficiência da Valva Tricúspide , Ferimentos e Lesões , Cordas Tendinosas/lesõesRESUMO
MitraClip (Abbott Vascular) therapy has been reported to be a safe and effective treatment for mitral regurgitation, even when the commissures are targeted. However, complications during the procedure may occur. We present a 44-year-old patient who underwent MitraClip implantation complicated by chordal rupture, resulting in emergent mitral valve replacement.
Assuntos
Cordas Tendinosas/lesões , Próteses Valvulares Cardíacas/efeitos adversos , Complicações Intraoperatórias , Insuficiência da Valva Mitral/cirurgia , Valva Mitral/cirurgia , Adulto , Ecocardiografia Transesofagiana , Humanos , Masculino , Valva Mitral/diagnóstico por imagem , Insuficiência da Valva Mitral/diagnóstico , RupturaRESUMO
A case is reported of iatrogenic mitral valve chordal rupture occurring during transcatheter aortic valve implantation (TAVI) with an inflatable and repositionable valve (Direct Flow; Direct Flow Medical, Santa Rosa, CA, USA). The specific implantation technique requires initial valve advancement into the left ventricular cavity, valve inflation within the ventricular cavity, and a final finely tuned valve upward pulling through the left ventricular outflow tract until contact with the aortic annulus is achieved. During this phase of the procedure, entangling with the mitral subvalvular apparatus should be excluded, to avoid inadvertent tissue tearing and consequent mitral valve malfunction. The present patient underwent TAVI but then developed symptomatic severe mitral valve regurgitation resulting from chordal rupture. The condition was successfully treated percutaneously by implanting a Mitra-Clip.
Assuntos
Cordas Tendinosas/lesões , Implante de Prótese de Valva Cardíaca/efeitos adversos , Insuficiência da Valva Mitral/etiologia , Idoso de 80 Anos ou mais , Valva Aórtica , Próteses Valvulares Cardíacas , Implante de Prótese de Valva Cardíaca/métodos , Humanos , Doença Iatrogênica , Complicações Intraoperatórias , Masculino , RupturaRESUMO
Transcatheter aortic valve implantation (TAVI) has emerged as a therapeutic option for high-risk aortic stenosis. Malposition of the prosthesis and severe residual aortic regurgitation are known complications of the procedure, which might require a second valve implantation. Although the implantation of a second valve seems to be an effective method, very few data are available describing this technique. Herein is reported a case of iatrogenic chordal rupture in a TAVI procedure which required a second valve implantation due to dislodgment of the first prosthesis.