Publications by authors named "Keith Buchan"

Anomalies of coronary venous system, the valve of the coronary sinus (Thebesian valve) and other cardiac malformations may make interventions through the coronary sinus difficult. These variants may pose a challenge in cannulating the coronary sinus for retrograde cardioplegia and for interventions performed through the coronary sinus by cardiac electrophysiologist/interventional cardiologist. Retrograde cardioplegia is an established method of myocardial protection with advantages, indications, and complications.

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Mitral valve function depends on its complex geometry and tissue health, with alterations in shape and tissue response affecting the long-term restorarion of function. Previous computational frameworks for biomechanical assessment are mostly based on patient-specific geometries; however, these are not flexible enough to yield a variety of models and assess mitral closure for individually tuned morphological parameters or material property representations. This study details the finite element approach implemented in our previously developed toolbox to assess mitral valve biomechanics and showcases its flexibility through the generation and biomechanical evaluation of different models.

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For patients awaiting urgent total laryngectomy who require coronary artery bypass grafting (CABG), the conventional median sternotomy should be avoided. We present a 69-year-old male who had urgent CABG as a prelude to an urgent laryngectomy for recurring laryngeal carcinoma. We recommend a manubrium-sparing T-shaped ministernotomy to preserve tissues and to avoid the disruption of the anatomy of the lower neck and superior mediastinum.

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Right ventricular haemangiomas are rare benign tumours, usually solitary and commonly located in the right heart. We report a 49-year-old female who presented with four masses in the right ventricle, three arising from the right ventricular free wall and one arising from the anterior leaflet of the tricuspid valve. She subsequently underwent total excision of the tumours and an anteroinferior commissuroplasty for severe tricuspid regurgitation complicating the excision.

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Aortic valve stenosis is the most common valve disease in the western world. Central to the pathogenesis of this disease is the growth of new blood vessels (angiogenesis) within the aortic valve allowing infiltration of immune cells and development of intra-valve inflammation. Identifying the cellular mediators involved in this angiogenesis is important as this may reveal new therapeutic targets which could ultimately prevent the progression of aortic valve stenosis.

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Article Synopsis
  • The study looked at the results of a heart surgery called surgical aortic valve replacement (SAVR) in over 31,000 people in the UK, including those who also had another surgery called CABG.
  • It found that the risk of dying from the surgery was low, around 1.9% for those with only SAVR and a bit higher for those who had CABG too.
  • The study showed that the type of surgery and the patient's health before surgery affected the outcomes, but most surgeries were planned ahead of time rather than done in emergencies.
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The mitral valve is a complex anatomical structure, whose shape is key to several traits of its function and disease, being crucial for the success of surgical repair and implantation of medical devices. The aim of this study was to develop a parametric, scalable, and clinically useful model of the mitral valve, enabling the biomechanical evaluation of mitral repair techniques through finite element simulations. MATLAB was used to parameterize the valve: the annular boundary was sampled from a porcine mitral valve mesh model and landmark points and relevant boundaries were selected for the parameterization of leaflets using polynomial fitting.

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Temporary epicardial pacing wires are used after cardiothoracic surgery to maintain a stable cardiac rhythm. They must be distinguished from the more commonly encountered transvenous temporary pacing wires, which are often used in coronary care units for the same purpose. Patients with temporary epicardial pacing wires may be transferred to hospital wards where these wires are not usually encountered, such as COVID wards, the general intensive care unit, the coronary care unit or general surgical wards if a laparotomy was required in the early period following cardiac surgery.

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The aim of this study was to assess whether the mechanical properties of mitral valve chordae tendineae are sensitive to being cross-linked under load. A total 64 chordae were extracted from eight porcine hearts. Two chordae (posterior basal) from each heart were subjected to uniaxial ramp testing and six chordae (two strut, two anterior basal and two posterior basal) were subjected to dynamic mechanical analysis over frequencies between 0.

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The aim of this study was to perform an initial assessment, in vitro, of the feasibility of using a glutaraldehyde cross-linked porcine mitral valve to retain acute functionality, focusing on assessing mitral regurgitation. Six porcine hearts were tested using an in vitro simulator. Testing was repeated following cross-linking of mitral valves; where cross-linking was achieved by placing them in a glutaraldehyde solution.

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Strut chordae, on their own, are not typically thought to aid mitral valve competence. The aim of this study is to assess whether strut chordae aid mitral valve competence during acute annular dilation. Twelve porcine hearts were dissected and tested using an simulator, with the mitral annulus tested in either a 'normal' or a dilated configuration.

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The mitral valve is a complex anatomical structure whose physiological functioning relies on the biomechanical properties and structural integrity of its components. Their compromise can lead to mitral valve dysfunction, associated with morbidity and mortality. Therefore, a review on the morphometry of the mitral valve is crucial, more specifically on the importance of valve dimensions and shape for its function.

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Background: The anatomy of the aortic root and its relationship to cardiac landmarks is important for valve-sparing surgery and understanding the pathology of lesions arising in this structure. Rapid understanding of the key anatomical details can be achieved by a geometrical concept based on the shape of a hexagon.

Methods: Definitions, structure, and key anatomical concepts of the aortic root according to the current literature were reviewed.

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The aim of this study was to determine the regional variation in viscoelastic properties of mitral valve leaflets over a range of physiological and patho-physiological frequencies. This included comparisons to be made between anterior and posterior leaflets, anterior leaflet clear and rough zones, and radial and circumferential leaflet orientation. Dynamic mechanical analysis was used to determine frequency-dependent viscoelastic properties.

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Background: Refractory post-cardiotomy cardiogenic shock (PCCS) is a relatively rare phenomenon that can lead to rapid multi-organ dysfunction syndrome and is almost invariably fatal without advanced mechanical circulatory support (AMCS), namely extra-corporeal membrane oxygenation (ECMO) or ventricular assist devices (VAD). In this multicentre observational study we retrospectively analyzed the outcomes of salvage venoarterial ECMO (VA ECMO) and VAD for refractory PCCS in the 3 adult cardiothoracic surgery centres in Scotland over a 20-year period.

Methods: The data was obtained through the Edinburgh, Glasgow and Aberdeen cardiac surgery databases.

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The importance of intratumour genetic and functional heterogeneity is increasingly recognised as a driver of cancer progression and survival outcome. Understanding how tumour clonal heterogeneity impacts upon therapeutic outcome, however, is still an area of unmet clinical and scientific need. TRACERx (TRAcking non-small cell lung Cancer Evolution through therapy [Rx]), a prospective study of patients with primary non-small cell lung cancer (NSCLC), aims to define the evolutionary trajectories of lung cancer in both space and time through multiregion and longitudinal tumour sampling and genetic analysis.

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A left completion pneumonectomy for primary lung cancer (left lower lobectomy) was complicated by sudden loss of ability to ventilate the patient through the double-lumen endotracheal tube. The problem could not be overcome by the anesthesiologist. In the face of impending cardiorespiratory arrest, a single-lumen tube was introduced through an incision in the left main bronchus through to the right main bronchus.

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Bilateral thoracotomies spaced at least 4 weeks apart are often required for the resection of bilateral pulmonary metastases. The anatomic distribution of the metastatic disease may rarely permit excision of bilateral pulmonary deposits through one thoracotomy incision. We demonstrate a successful bilateral pulmonary metastasectomy in the right upper lobe, right middle lobe, and left upper lobe through a right thoracotomy in a 40-year-old man with a past history of rectal adenocarcinoma and of left open pulmonary metastasectomy 1 year previously.

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