Minimally Invasive Right Anterior Mini-Thoracotomy Aortic Valve Replacement

Since the emergence of small skin incision aortic valve surgery in the late 1990s, minimally invasive aortic valve replacement has now become a viable alternative to standard full sternotomy. The spectrum includes (a) upper hemi sternotomy (T or J shaped), (b) lower partial sternotomy, and (c) right anterior mini-thoracotomy. Potential advantages include a cosmetically appealing scar, decreased post-operative pain and bleeding, shorter ventilation time and hospital stay, and early return to active life. The operative challenges include restricted view and access to the operative field, longer aortic cross-clamp time, and cardiopulmonary bypass time. This necessitates detailed pre-operative imaging, correct selection and assessment of patients, and good communication with perfusionists and anesthetists regarding the plan of each surgery, with a solid back-up plan in case conversion to full sternotomy is required intra-operatively. In recent times, the use of suture less valves and rapid deployment bio prosthesis has dramatically reduced operative time. Here, we describe the work-up, selection criteria, key steps, and potential pitfalls of the right anterior mini-thoracotomy approach for aortic valve replacement

Challenges in the Commencement of Consultant Surgical Practice: A Study of Threshold Concepts in Junior Cardiothoracic Surgeons

The transition from trainee to consultant cardiothoracic surgeon may be challenging. Curricula for cardiothoracic surgical training and for the professional development of cardiothoracic surgeons need to address the issues in transition that are the most difficult. This research used threshold concepts to identify the areas within this transition that are the most problematic. Semi-structured, in-depth, face-to-face, individual interviews were conducted with 13 junior cardiothoracic surgeons (in practice for ten years or less) who were purposively recruited. Transcripts were generated from the interviews and subjected to thematic analysis. Data was independently analysed by three researchers. Problematic areas in the transition to consultant practice included: (1) taking ultimate responsibility for patient care including clinical judgment, decision-making and unsupervised operating; (2) designing a career; (3) navigating new work environments; (4) managing relationships with colleagues, trainees and other team members; (5) managing technical challenges; (6) managing the previously unseen or unexpected; and (7) coping with adverse events. Uncertainty associated with each of these challenges was the most prominent threshold concept. Successfully addressing some or all of these problematic areas resulted in (8) change as a person or surgeon that positively influenced each individual’s sense of worth and identity as a cardiothoracic surgeon. Despite the completion of surgical education and training, time and the passing of the Fellowship examination, significant challenges remain for individuals commencing cardiothoracic surgical practice. There exist further curricular opportunities for the education of senior trainees and for the professional development of junior consultant surgeons to assist in the negotiation of these challenges

Fowler-Nordheim-like local injection of photoelectrons from a silicon tip

Tunneling between a photo-excited p-type silicon tip and a gold surface is studied as a function of tip bias, tip/sample distance and light intensity. In order to extend the range of application of future spin injection experiments, the measurements are carried out under nitrogen gas at room temperature. It is found that while tunneling of valence band electrons is described by a standard process between the semiconductor valence band and the metal, the tunneling of photoelectrons obeys a Fowler-Nordheim-like process directly from the conduction band. In the latter case, the bias dependence of the photocurrent as a function of distance is in agreement with theoretical predictions which include image charge effects. Quantitative analysis of the bias dependence of the dark and photocurrent spectra gives reasonable values for the distance, and for the tip and metal work functions. For small distances image charge effects induce a vanishing of the barrier and the bias dependence of the photocurrent is exponential. In common with many works on field emission, fluctuations in the tunneling currents are observed. These are mainly attributed to changes in the prefactor for the tunneling photocurrent, which we suggest is caused by an electric-field-induced modification of the thickness of the natural oxide layer covering the tip apex.Comment: 12 pages, 11 figures. Submitted to Phys. Rev.

Spontaneous Chelation-Driven Reduction of the Neptunyl Cation in Aqueous Solution.

Octadentate hydroxypyridinone (HOPO) and catecholamide (CAM) siderophore analogues are known to be efficacious chelators of the actinide cations, and these ligands are also capable of facilitating both activation and reduction of actinyl species. Utilizing X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopies, as well as cyclic voltammetry measurements, herein, we elucidate chelation-based mechanisms for driving reactivity and initiating redox processes in a family of neptunyl-HOPO and CAM complexes. Based on the selected chelator, the ability to control the oxidation state of neptunium and the speed of reduction and concurrent oxo group activation was demonstrated. Most notably, reduction kinetics for the NpV O2 +/ /NpIV redox couple upon chelation by the ligands 3,4,3-LI(1,2-HOPO) and 3,4,3-LI(CAM)2 (1,2-HOPO)2 was observed to be faster than ever reported, and in fact quicker than we could measure using either X-ray absorption spectroscopy or electrochemical techniques

Acute pulmonary embolectomy

Acute pulmonary embolism (PE) is a common condition frequently associated with a high mortality worldwide. It can be classified into non-massive, sub-massive and massive, based on the degree of haemodynamic compromise. Surgical pulmonary embolectomy, despite having been in existence for over 100 years, is generally regarded as an option of last resort, with expectedly high mortality rates. Recent advances in diagnosis and recognition of key qualitative predictors of mortality, such as right ventricular stress on echocardiography, have enabled the re-exploration of surgical pulmonary embolectomy for use in patients prior to the development of significant circulatory collapse, with promising results. We aim to review the literature and discuss the indications, perioperative workup and outcomes of surgical pulmonary embolectomy in the management of acute P