BackgroundThe evidence on the impact of patient-prosthesis Mismatch (PPM) on survival thus far has been conflicting. The aim of this study was to 1) study the effect of PPM on survival after isolated aortic and mitral valve replacement and 2) Assess the interaction between left ventricular function and PPM on survival.MethodsThe study cohort was patients who underwent isolated Aortic valve replacement (AVR) and Mitral valve replacement (MVR) over a 10-year period from 2008 to 2018. PPM was defined using the projected indexed effective orifice area (EOAi). The cohort was divided into different groups based on the degree of PPM. The severity of PPM was classified using threshold values of EOAi used in the literature. The Kaplan- Meier method was used to compare survival by degree of PPM. Multivariate Cox proportional hazards models were used to generate adjusted hazard ratios (HR) with 95% confidence intervals. An interactive term for ejection fraction (EF) was added to test whether EF modifies the effect of the PPM grade on survival. In addition, sub-group analysis based on left ventricular function was performed.ResultsIn the AVR cohort, there were a total of 1953 patients. The distribution of patients in the different PPM categories was as follows: no PPM 59.7%; moderate PPM 36.8%; severe PPM 3.5%. There was no significant difference in survival between the different groups. At 10 years, the adjusted HR between patients with severe PPM versus no PPM was 1.1(CI 0.5–2.4, p > 0.05) and the HR between those with moderate PPM versus no PPM was 0.97 (CI 0.74–1.23, p > 0.05). In the MVR cohort, there were a total of 298 patients. The distribution of PPM is as follows: no PPM 59.4%; and with PPM 40.6%. Again, there was no significant difference in survival between the groups. At 5 years, the adjusted HR between patients with PPM versus no PPM was 1.45 (CI 0.67–3.14, p > 0.05). In both groups, there was no significant interaction between left ventricular function (LVF) and degree of PPM on survival.ConclusionsIn our study cohort, the degree of PPM was not an independent predictor of survival after AVR or MVR. There was also no significant interaction between LV function and degree of PPM on survival.
Accurate quantification of absorbed radiation dose is important for safe and effective delivery of radiation therapy. An important aspect to this is reference dosimetry, which is performed under reference conditions specified by international codes of practice. Such measurements are usually performed in a water phantom. In the Sun Nuclear Corporation (SNC) three-dimensional (3D) scanner water tank system the detector holder is fixed to a horizontal metallic drive rail (MDR) which is in close proximity to the active volume of the detector. In this project, the dosimetric effects of the MDR on reference dosimetry were investigated for MV photons, MeV electrons, and kV photons by comparing reference dosimetry measurements in the SNC 3D scanner against similar measurements in a Standard Imaging (SI) one-dimensional (1D) tank and against measurements in the SNC 3D scanner with an additional, custom-made spacer placed beneath the chamber holder to increase the chamber -MDR separation. A second experiment investigated the difference in chamber reading dependent on chamber to MDR separation by fixing the chamber in the tank independently of the MDR and successively moving the MDR vertically to alter the separation. The results showed that measurements in the SNC 3D scanner agree with both SI 1D tank and SNC 3D scanner with spacer to within ±0.3% for MV photons, ±0.1% for electrons and ±1.2% for kV photons within the calculated setup uncertainty. The second experiment showed that the contribution of backscatter from the MDR was significant if the distance between MDR and chamber was reduced below the chamber's designed position in the SNC 3D scanner. The exception was for kV photons where the contribution of backscatter from the MDR was measured to be 0.5% at the designed distance. Further investigation would be useful for kV photons, where the experiment showed relatively large measurement uncertainties. K E Y W O R D S3D scanner, backscatter, reference dosimetry, water tank ---
Introduction:Since its revival two decades ago development of the surgical technique, along with evidence and clinical outcomes of off-pump coronary artery bypass surgery (OPCAB) were brought into focus. Methods: We report a single surgeon, single center experience of the first 37 consecutive patients undergoing off-pump surgery. Patients were selected for OPCAB (study group) individually and matched retrospectively to a control group of 113 patients performed over an identical time frame. Data were retrieved from a hospital data base (TOMCAT). Results: Mean Logistic European System of Cardiac Operative Risk Stratification (EuroSCORE) was slightly higher in the off-pump group (3.8% versus 2.9%). One patient died during the study and this was in the off-pump CAB group (OPCAB-30 day mortality 2.7%). Operating time was slightly shorter in the off-pump group (3 hours 28 minutes versus 3 hours 49 minutes, p = 0.15). After exclusion of outliers, total hospital stay was significantly shorter for off-pump cases (mean 6.8 days versus 8.37 days), while Intensive Care Unit (ICU) stay (1.2 versus 1.4 days) and ventilation time were only slightly shorter (9.35 hours versus 10.6 hours) for off-pump cases. Chest tube drainage was significantly lower in the off-pump group (484 ml versus 744 ml, p = 0.04) with correspondingly slightly lower transfusion requirements and significantly increased discharge haemoglobin concentrations in OPCAB. There was one cerebrovascular accident (CVA) in the off-pump group and none in the on-pump group. Conclusion: In this study we show short term outcomes for introduction of off-pump into surgical technique. Length of ICU stay, ventilation times, chest tube drainage, transfusion requirements and pre-discharge haemoglobin concentration all appeared superior in the off pump group. The off-pump technique was safely introduced into the surgeon's service with relatively little mortality. Experience of surgeon was considered advantageous for fast adaption of the technique. However, numbers were too small to make strong inferences. With practice more patients should benefit from the technique. of refinements have been made in anaesthetic and surgical techniques, such as designs of pumps, oxygenators and cannulae, and advantage from avoiding ECC, reduced morbidity was not impressively apparent throughout the studies. Overall proportion of isolated off-pump CABG is currently 20.2% for the European countries [3] and about 25% in the US [4]. In Asian countries majority of CABG surgery is performed off-pump. There are European institutions that report particularly high percentages of off-pump CABG with dedicated training programs for surgical trainees [5,6]. Applying CABG may reduce costs, one of the reasons it lead to application in South Africa and revival of the technique in early 1990s. With low intraoperative conversion rate (≤8.5%) costs can be reduced [7]. Currently there is no guideline suggesting off-pump as technique of first choice in any
conditions, a syringe and needle are used to administer 30ml of 0.25% bupivacaine with 1:200,000 adrenaline percutaneously to the peritendinous tissues, avoiding intratendinous injection. Tendons are harvested intraoperatively using an open ended tendon stripper. DISCUSSIONPrevious reports have described techniques to administer local anaesthetic to the hamstrings tendon bed via the harvest tract after graft harvest. 2,3 In these descriptions, the injection was given via a blunt device such as a suction catheter or arthroscopic shaver sleeve into the donor site space, without image guidance. The use of ultrasonography guidance allows anaesthetic to be introduced to the target site with improved accuracy. In addition, it allows the safe use of a hypodermic needle, allowing peritendinous tissue infiltration rather than simple filling of a dead space. We have performed this technique without complication in 14 patients. Postoperative pain scores were uniformly low and all were discharged successfully as day cases.
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