Unusual cause of myocardial infarction and congestive heart failure in a patient with prosthetic valve endocarditis

In a patient with staphylococcus lugdunensis prosthetic aortic valve endocarditis and coronary septic embolism accompanied by antero-lateral myocardial infarction, embolic material was successfully aspirated from the bifurcation of the left anterior descending coronary artery and the first diagonal branch. A good angiographic result was documented six months thereafter when the patient presented with a second complication, pulsatile compression of the left main coronary artery by an abscess cavity originating between the aortic and mitral annulus, leading to congestive heart failure. The patient underwent successful surgical replacement of the aortic valve prosthesis with concomitant patch reconstruction of the annulus as well as tricuspid annuloplasty.

Mid-term results of aortic root replacement using a self-assembled biological composite graft.

OBJECTIVES To report the mid-term results of aortic root replacement using a self-assembled biological composite graft, consisting of a vascular tube graft and a stented tissue valve. METHODS Between January 2005 and December 2011, 201 consecutive patients [median age 66 (interquartile range, IQR, 55-77) years, 31 female patients (15.4%), median logistic EuroSCORE 10 (IQR 6.8-23.2)] underwent aortic root replacement using a stented tissue valve for the following indications: annulo-aortic ectasia or ascending aortic aneurysm with aortic valve disease in 162 (76.8%) patients, active infective endocarditis in 18 (9.0%) and acute aortic dissection Stanford type A in 21 (10.4%). All patients underwent clinical and echocardiographic follow-up. We analysed survival and valve-related events. RESULTS The overall in-hospital mortality rate was 4.5%. One- and 5-year cardiac-related mortality rates were 3 and 6%, and overall survival was 95 ± 1.5 and 75 ± 3.6%, respectively. The rate of freedom from structural valve failure was 99% and 97 ± 0.4% at the 1- and 5-year follow-up, respectively. The incidence rates of prosthetic valve endocarditis were 3 and 4%, respectively. During a median follow-up of 28 (IQR 14-51) months, only 2 (1%) patients required valve-related redo surgery due to prosthetic valvular endocarditis and none suffered from thromboembolic events. One percent of patients showed structural valve deterioration without any clinical symptoms; none of the patients suffered greater than mild aortic regurgitation. CONCLUSIONS Aortic root replacement using a self-assembled biological composite graft is an interesting option. Haemodynamic results are excellent, with freedom from structured valve failure. Need for reoperation is extremely low, but long-term results are necessary to prove the durability of this concept.

Effect of B-type Natriuretic Peptides on Long-Term Outcomes After Transcatheter Aortic Valve Implantation.

B-type natriuretic peptide (BNP) levels are elevated in patients with aortic stenosis (AS) and decrease acutely after replacement of the stenotic valve. The long-term prognostic value of BNP after transcatheter aortic valve implantation (TAVI) and the relative prognostic utility of single versus serial peri-interventional measurements of BNP and N-terminal prohormone BNP (NT-pro-BNP) are unknown. This study sought to determine the impact of BNP levels on long-term outcomes after TAVI and to compare the utility of BNP versus NT-pro-BNP measured before and after intervention. We analyzed 340 patients with severe AS and baseline pre-TAVI assessment of BNP. In 219 patients, BNP and NT-pro-BNP were measured serially before and after intervention. Clinical outcomes over 2 years were recorded. Patients with high baseline BNP (higher tertile ≥591 pg/ml) had increased risk of all-cause mortality (adjusted hazard ratio 3.16, 95% confidence interval 1.84 to 5.42; p <0.001) and cardiovascular death at 2 years (adjusted hazard ratio 3.37, 95% confidence interval 1.78 to 6.39; p <0.001). Outcomes were most unfavorable in patients with persistently high BNP before and after intervention. Comparing the 2 biomarkers, NT-pro-BNP levels measured after TAVI showed the highest prognostic discrimination for 2-year mortality (area under the curve 0.75; p <0.01). Baseline-to-discharge reduction, but not baseline levels of BNP, was related to New York Heart Association functional improvement. In conclusion, high preintervention BNP independently predicts 2-year outcomes after TAVI, particularly when elevated levels persist after the intervention. BNP and NT-pro-BNP and their serial periprocedural changes provide complementary prognostic information for symptomatic improvement and survival.

Hydrodynamic evaluation of kangaroo aortic valve matrices for tissue valve engineering

We evaluated the hydrodynamic performance of kangaroo aortic valve matrices (KMs) (19, 21, and 23 mm), as potential scaffolds in tissue valve engineering using a pulsatile left heart model at low and high cardiac outputs (COs) and heart rates (HRs) of 60 and 90 beats/min. Data were measured in two samples of each type, pooled in two CO levels (2.1 +/- 0.7 and 4.2 +/- 0.6 L/min; mean +/- standard errors on the mean), and analyzed using analysis of variance with CO level, HR, and valve type as fixed factors and compared to similar porcine matrices (PMs). Transvalvular pressure gradient (Delta P) was a function of HR (P < 0.001) and CO (P < 0.001) but not of valve type (P = 0.39). Delta P was consistently lower in KMs but not significantly different from PMs. The effective orifice area and performance index of kangaroo matrices was statistically larger for all sizes at both COs and HRs.

Clinically indicated replacement versus routine replacement of peripheral venous catheters (Review)

Background Centers for Disease Control Guidelines recommend replacement of peripheral intravenous (IV) catheters every 72 to 96 hours. Routine replacement is thought to reduce the risk of phlebitis and bacteraemia. Catheter insertion is an unpleasant experience for patients and replacement may be unnecessary if the catheter remains functional and there are no signs of inflammation. Costs associated with routine replacement may be considerable. Objectives To assess the effects of removing peripheral IV catheters when clinically indicated compared with removing and re-siting the catheter routinely.

Biomechanical force displacement analysis of strength of fixation of tracker holding devices to bone in computer aided joint replacement

Computer aided joint replacement surgery has become very popular during recent years and is being done in increasing numbers all over the world. The accuracy of the system depends to a major extent, on accurate registration and immobility of the tracker attachment devices to the bone. This study was designed to asses the forces needed to displace the tracker attachment devices in the bone simulators. Bone simulators were used to maintain the uniformity of the bone structure during the study. The fixation devices tested were 3mm diameter self drilling, self tapping threaded pin, 4mm diameter self tapping cortical threaded pin, 5mm diameter self tapping cancellous threaded pin and a triplanar fixation device ‘ortholock’ used with three 3mm pins. All the devices were tested for pull out, translational and rotational forces in unicortical and bicortical fixation modes. Also tested was the normal bang strength and forces generated by leaning on the devices. The forces required to produce translation increased with the increasing diameter of the pins. These were 105N, 185N, and 225N for the unicortical fixations and 130N, 200N, 225N for the bicortical fixations for 3mm, 4mm and 5mm diameter pins respectively. The forces required to pull out the pins were 1475N, 1650N, 2050N for the unicortical, 1020N, 3044N and 3042N for the bicortical fixated 3mm, 4mm and 5mm diameter pins. The ortholock translational and pull out strength was tested to 900N and 920N respectively and still it did not fail. Rotatory forces required to displace the tracker on pins was to the magnitude of 30N before failure. The ortholock device had rotational forces applied up to 135N and still did not fail. The manual leaning forces and the sudden bang forces generated were of the magnitude of 210N and 150N respectively. The strength of the fixation pins increases with increasing diameter from three to five mm for the translational forces. There is no significant difference in pull out forces of four mm and five mm diameter pins though it is more that the three mm diameter pins. This is because of the failure of material at that stage rather than the fixation device. The rotatory forces required to displace the tracker are very small and much less that that can be produced by the surgeon or assistants in single pins. Although the ortholock device was tested to 135N in rotation without failing, one has to be very careful not to put any forces during the operation on the tracker devices to ensure the accuracy of the procedure.

The concentric all-polyethylene Exeter acetabular component in primary total hip replacement

We report the long term outcome of the flangeless, cemented all polyethylene Exeter cup at a mean of 14.6 years (range 10-17) after operation. Of the 263 hips in 243 patients, 122 hips are still in situ, 112 patients (119 hips) have died, eighteen hips were revised, and three patients (four hips) had moved abroad and were lost to follow-up (1.5%). Radiographs demonstrated two sockets had migrated and six more had radiolucent lines in all three zones. The Kaplan Meier survivorship at 15 years with endpoint revision for all causes is 89.9% (95% CI 84.6 to 95.2%) and for aseptic cup loosening or lysis 91.7% (CI 86.6 to 96.8%). In 210 hips with a diagnosis of primary osteoarthritis survivorship for all causes is 93.2% (95% CI 88.1 to 98.3%), and for aseptic cup loosening 95.0% (CI 90.3 to 99.7%). The cemented all polyethylene Exeter cup has an excellent long-term survivorship.

A ‘cost-per-wear’ model based on contact lens replacement frequency

Purpose: The aim was to construct and advise on the use of a cost-per-wear model based on contact lens replacement frequency, to form an equitable basis for cost comparison. ---------- Methods: The annual cost of professional fees, contact lenses and solutions when wearing daily, two-weekly and monthly replacement contact lenses is determined in the context of the Australian market for spherical, toric and multifocal prescription types. This annual cost is divided by the number of times lenses are worn per year, resulting in a ‘cost-per-wear’. The model is presented graphically as the cost-per-wear versus the number of times lenses are worn each week for daily replacement and reusable (two-weekly and monthly replacement) lenses.---------- Results: The cost-per-wear for two-weekly and monthly replacement spherical lenses is almost identical but decreases with increasing frequency of wear. The cost-per-wear of daily replacement spherical lenses is lower than for reusable spherical lenses, when worn from one to four days per week but higher when worn six or seven days per week. The point at which the cost-per-wear is virtually the same for all three spherical lens replacement frequencies (approximately AUD$3.00) is five days of lens wear per week. A similar but upwardly displaced (higher cost) pattern is observed for toric lenses, with the cross-over point occurring between three and four days of wear per week (AUD$4.80). Multifocal lenses have the highest price, with cross-over points for daily versus two-weekly replacement lenses at between four and five days of wear per week (AUD$5.00) and for daily versus monthly replacement lenses at three days per week (AUD$5.50).---------- Conclusions: This cost-per-wear model can be used to assist practitioners and patients in making an informed decision in relation to the cost of contact lens wear as one of many considerations that must be taken into account when deciding on the most suitable lens replacement modality.

A robust structure and motion replacement for bundle adjustment

This paper demonstrates the application of a robust form of pose estimation and scene reconstruction using data from camera images. We demonstrate results that suggest the ability of the algorithm to rival methods of RANSAC based pose estimation polished by bundle adjustment in terms of solution robustness, speed and accuracy, even when given poor initialisations. Our simulated results show the behaviour of the algorithm in a number of novel simulated scenarios reflective of real world cases that show the ability of the algorithm to handle large observation noise and difficult reconstruction scenes. These results have a number of implications for the vision and robotics community, and show that the application of visual motion estimation on robotic platforms in an online fashion is approaching real-world feasibility.

Lineage replacement accompanying duplication and rapid fixation of an RNA element in the nsP3 gene in a species of alphavirus

A sequence of thirty-six nucleotides in the nsP3 gene of Ross River virus (RRV), coding for the amino acid sequence HADTVSLDSTVS, was duplicated some time between 1969 and 1979 coinciding with the appearance of a new lineage of this virus and with a major outbreak of Epidemic Polyarthritis among residents of the Pacific Islands. This lineage of RRV continues to circulate throughout Australia and both earlier lineages, which lacked the duplicated element, now are extinct. Multiple copies of several other elements also were observed in this region of the nsP3 gene in all lineages of RRV. Multiple copies of one of these, coding for the amino acid sequence P*P*PR, were detected in the C-terminal region of the nsP3 protein of all alphaviruses except those of African origin. The fixation of duplications and insertions in 3' region of nsP3 genes from all lineages of alphaviruses, suggests they provide some fitness advantage

Reliability analysis and economic equipment replacement appraisal for substation and sub-transmission systems with explicit inclusion of non-repairable failures

The modern society has come to expect the electrical energy on demand, while many of the facilities in power systems are aging beyond repair and maintenance. The risk of failure is increasing with the aging equipments and can pose serious consequences for continuity of electricity supply. As the equipments used in high voltage power networks are very expensive, economically it may not be feasible to purchase and store spares in a warehouse for extended periods of time. On the other hand, there is normally a significant time before receiving equipment once it is ordered. This situation has created a considerable interest in the evaluation and application of probability methods for aging plant and provisions of spares in bulk supply networks, and can be of particular importance for substations. Quantitative adequacy assessment of substation and sub-transmission power systems is generally done using a contingency enumeration approach which includes the evaluation of contingencies, classification of the contingencies based on selected failure criteria. The problem is very complex because of the need to include detailed modelling and operation of substation and sub-transmission equipment using network flow evaluation and to consider multiple levels of component failures. In this thesis a new model associated with aging equipment is developed to combine the standard tools of random failures, as well as specific model for aging failures. This technique is applied in this thesis to include and examine the impact of aging equipments on system reliability of bulk supply loads and consumers in distribution network for defined range of planning years. The power system risk indices depend on many factors such as the actual physical network configuration and operation, aging conditions of the equipment, and the relevant constraints. The impact and importance of equipment reliability on power system risk indices in a network with aging facilities contains valuable information for utilities to better understand network performance and the weak links in the system. In this thesis, algorithms are developed to measure the contribution of individual equipment to the power system risk indices, as part of the novel risk analysis tool. A new cost worth approach was developed in this thesis that can make an early decision in planning for replacement activities concerning non-repairable aging components, in order to maintain a system reliability performance which economically is acceptable. The concepts, techniques and procedures developed in this thesis are illustrated numerically using published test systems. It is believed that the methods and approaches presented, substantially improve the accuracy of risk predictions by explicit consideration of the effect of equipment entering a period of increased risk of a non-repairable failure.