Assessing the impact of PV panel climate-based degradation rates on inverter reliability in grid-connected solar energy systems.

This paper provides an evaluation of a 4-kW grid-connected full-bridge PV inverter under three different scenarios to assess its reliability with a fixed PV degradation rate, with a climate-based degradation rate, and without considering PV degradation. The climate-based degradation rates are estimated using a physics-based model that considers the different parameters influencing the PV reliability. Three different locations representing three different climate zones (hot and dry, hot and humid, and moderate climates) have been chosen in this study. The estimated lifetime of the IGBT, the switching device in the PV inverter, varies depending on the location, with the inclusion of fixed and climate-based degradation rates extending the lifespan of the PV inverter in the examined locations. The results demonstrate the significant impact of PV climate-based degradation rates on power electronics' reliability assessment and the importance of considering various factors in predicting device failures. To ensure the PV inverter's lifespan over the desired period in areas with high solar irradiation rates and extremely hot climates, the design parameters should be slightly elevated above the standard value.

The value of telemonitoring and ICT-guided disease management in heart failure: Results from the IN TOUCH study.

AIM: It is still unclear whether telemonitoring reduces hospitalization and mortality in heart failure (HF) patients and whether adding an Information and Computing Technology-guided-disease-management-system (ICT-guided-DMS) improves clinical and patient reported outcomes or reduces healthcare costs. METHODS: A multicenter randomized controlled trial was performed testing the effects of INnovative ICT-guided-DMS combined with Telemonitoring in OUtpatient clinics for Chronic HF patients (IN TOUCH) with in total 179 patients (mean age 69 years; 72% male; 77% in New York Heart Association Classification (NYHA) III-IV; mean left ventricular ejection fraction was 28%). Patients were randomized to ICT-guided-DMS or to ICT-guided-DMS+telemonitoring with a follow-up of nine months. The composite endpoint included mortality, HF-readmission and change in health-related quality of life (HR-QoL). RESULTS: In total 177 patients were eligible for analyses. The mean score of the primary composite endpoint was -0.63 in ICT-guided-DMS vs. -0.73 in ICT-guided-DMS+telemonitoring (mean difference 0.1, 95% CI: -0.67 +0.82, p=0.39). All-cause mortality in ICT-guided-DMS was 12% versus 15% in ICT-guided-DMS+telemonitoring (p=0.27); HF-readmission 28% vs. 27% p=0.87; all-cause readmission was 49% vs. 51% (p=0.78). HR-QoL improved in most patients and was equal in both groups. Incremental costs were €1360 in favor of ICT-guided-DMS. ICT-guided-DMS+telemonitoring had significantly fewer HF-outpatient-clinic visits (p<0.01). CONCLUSION: ICT-guided-DMS+telemonitoring for the management of HF patients did not affect the primary and secondary endpoints. However, we did find a reduction in visits to the HF-outpatient clinic in this group suggesting that telemonitoring might be safe to use in reorganizing HF-care with relatively low costs.

A 21% conversion rate to total knee arthroplasty of a first-generation patellofemoral prosthesis at a mean follow-up of 9.7 years.

PURPOSE: To evaluate the mid- to long-term results of the Richards' type II patellofemoral arthroplasty (PFA) in terms of functional scores, number and type of complications, patient satisfaction and survival. METHODS: We retrospectively studied patients that received a Richards' type II PFA at our institution between 1998 and 2007. Patients with a functioning PFA at the time of this study were evaluated. Outcomes included survival rates with endpoint loss of prosthesis, number and type of complications, Knee Society Scores (KSS) and Visual Analogue Scale (VAS) for pain. In addition, patients were asked how surgery influenced their original symptoms. RESULTS: Twenty-four patients (33 prostheses) were included. Follow-up ranged from 2.2 to 18.8 years with a mean of 9.7 years. Survival at 10 years was 73% (95% CI, 57-93%). Median KSS score was 163 (range, 110-200). Median VAS Pain was 30 (range, 0-80) and VAS Satisfaction median was 90 (range, 50-100). Thirteen (62%) PFAs were rated excellent, six (28%) as good and two (10%) as fair. Twelve (36%) of the cases required further surgery within 4 years after implantation. Seven of these (21%) were converted to TKA after a mean time of 5.5 years, five out of seven were converted because of ongoing tibiofemoral osteoarthritis (TFOA). CONCLUSIONS: We found a rate of 21% (7/33) conversion of the Richards' II PFA to TKA after a mean of 5.5 years; 71% (5/7) of cases were because of TFOA. We strongly advise not to use PFA if there is any sign of joint disease in other compartments than patellofemoral.

Long-term follow-up in optimally treated and stable heart failure patients: primary care vs. heart failure clinic. Results of the COACH-2 study.

AIMS: It has been suggested that home-based heart failure (HF) management in primary care may be an alternative to clinic-based management in HF patients. However, little is known about adherence to HF guidelines and adherence to the medication regimen in these home-based programmes. The aim of the current study was to determine whether long-term follow-up and treatment in primary care is equally effective as follow-up at a specialized HF clinic in terms of guideline adherence and patient adherence, in HF patients initially managed and up-titrated to optimal treatment at a specialized HF clinic. METHODS AND RESULTS: We conducted a multicentre, randomized, controlled study in 189 HF patients (62% male, age 72 ± 11 years), who were assigned to follow-up either in primary care (n = 97) or in a HF clinic (n = 92). After 12 months, no differences between guideline adherence, as estimated by the Guideline Adherence Indicator (GAI-3), and patient adherence, in terms of the medication possession ratio (MPR), were found between treatment groups. There was no difference in the number of deaths (n = 12 in primary care and n = 8 in the HF clinic; P = 0.48), and hospital readmissions for cardiovascular (CV) reasons were also similar. The total number of unplanned non-CV hospital readmissions, however, tended to be higher in the primary care group (n = 22) than in the HF clinic group (n = 10; P = 0.05). CONCLUSIONS: Patients discharged after initial management in a specialized HF clinic can be discharged to primary care for long-term follow-up with regard to maintaining guideline adherence and patient adherence. However, the complexity of the HF syndrome and its associated co-morbidities requires continuous monitoring. Close collaboration between healthcare providers will be crucial in order to provide HF patients with optimal, integrated care.

Perceived barriers of heart failure nurses and cardiologists in using clinical decision support systems in the treatment of heart failure patients.

BACKGROUND: Clinical Decision Support Systems (CDSSs) can support guideline adherence in heart failure (HF) patients. However, the use of CDSSs is limited and barriers in working with CDSSs have been described as a major obstacle. It is unknown if barriers to CDSSs are present and differ between HF nurses and cardiologists. Therefore the aims of this study are; 1. Explore the type and number of perceived barriers of HF nurses and cardiologists to use a CDSS in the treatment of HF patients. 2. Explore possible differences in perceived barriers between two groups. 3. Assess the relevance and influence of knowledge management (KM) on Responsibility/Trust (R&T) and Barriers/Threats (B&T). METHODS: A questionnaire was developed including; B&T, R&T, and KM. For analyses, descriptive techniques, 2-tailed Pearson correlation tests, and multiple regression analyses were performed. RESULTS: The response- rate of 220 questionnaires was 74%. Barriers were found for cardiologists and HF nurses in all the constructs. Sixty-five percent did not want to be dependent on a CDSS. Nevertheless thirty-six percent of HF nurses and 50% of cardiologists stated that a CDSS can optimize HF medication. No relationship between constructs and age; gender; years of work experience; general computer experience and email/internet were observed. In the group of HF nurses a positive correlation (r .33, P<.01) between years of using the internet and R&T was found. In both groups KM was associated with the constructs B&T (B=.55, P=<.01) and R&T (B=.50, P=<.01). CONCLUSIONS: Both cardiologists and HF-nurses perceived barriers in working with a CDSS in all of the examined constructs. KM has a strong positive correlation with perceived barriers, indicating that increasing knowledge about CDSSs can decrease their barriers.

Health professionals' expectations versus experiences of internet-based telemonitoring: survey among heart failure clinics.

BACKGROUND: Although telemonitoring is increasingly used in heart failure care, data on expectations, experiences, and organizational implications concerning telemonitoring are rarely addressed, and the optimal profile of patients who can benefit from telemonitoring has yet to be defined. OBJECTIVE: To assess the actual status of use of telemonitoring and to describe the expectations, experiences, and organizational aspects involved in working with telemonitoring in heart failure in the Netherlands. METHODS: In collaboration with the Netherlands Organization for Applied Scientific Research (TNO), a 19-item survey was sent to all outpatient heart failure clinics in the Netherlands, addressed to cardiologists and heart failure nurses working in the clinics. RESULTS: Of the 109 heart failure clinics who received a survey, 86 clinics responded (79%). In total, 31 out of 86 (36%) heart failure clinics were using telemonitoring and 12 heart failure clinics (14%) planned to use telemonitoring within one year. The number of heart failure patients receiving telemonitoring generally varied between 10 and 50; although in two clinics more than 75 patients used telemonitoring. The main goals for using telemonitoring are "monitoring physical condition", "monitoring signs of deterioration" (n=39, 91%), "monitoring treatment" (n=32, 74%), "adjusting medication" (n=24, 56%), and "educating patients" (n=33, 77%). Most patients using telemonitoring were in the New York Heart Association (NYHA) functional classes II (n=19, 61%) and III (n=27, 87%) and were offered the use of the telemonitoring system "as long as needed" or without a time limit. However, the expectations of the use of telemonitoring were not met after implementation. Eight of the 11 items about expectations versus experiences were significantly decreased (P<.001). Health care professionals experienced the most changes related to the use of telemonitoring in their work, in particular with respect to "keeping up with current development" (before 7.2, after 6.8, P=.15), "being innovative" (before 7.0, after 6.1, P=.003), and "better guideline adherence" (before 6.3, after 5.3, P=.005). Strikingly, 20 out of 31 heart failure clinics stated that they were considering using a different telemonitoring system than the system used at the time. CONCLUSIONS: One third of all heart failure clinics surveyed were using telemonitoring as part of their care without any transparent, predefined criteria of user requirements. Prior expectations of telemonitoring were not reflected in actual experiences, possibly leading to disappointment.

Follow-up and treatment of an instable patient with heart failure using telemonitoring and a computerised disease management system: a case report.

In the last decades, the introduction of information and communication technology (ICT) in healthcare promised an improved quality of care while reducing workload and improving cost-effectiveness. This might be realised by the use of computer guided decision support systems and telemonitoring. This case study describes the process of care of a patient with chronic heart failure, who was treated with a computerised disease management system in combination with telemonitoring. With the help of these appliances, we think we were probably able to prevent at least two readmissions for heart failure in a period of 10 months. We also gained more insight into patient's behaviour with regards to compliance with the heart failure regimen at home. Frequent contact at distance and the online availability of physiological measurements at home facilitated patient tailored education and helped the patient to react adequately to symptoms of deterioration. Additionally, up-titration of heart failure medication was performed without contacting the patient at the outpatient clinic.

Unilateral facet dislocation: always reduce?

A unilateral facet dislocation noted in a 17-year-old boy after an axial cervical trauma proved to be an incidentally encountered preexisting lesion, most likely originating from a forceps delivery at birth. The surgical treatment initially considered was converted to a conservative approach, with full clinical recovery.

The value of INnovative ICT guided disease management combined with Telemonitoring in OUtpatient clinics for Chronic Heart failure patients. Design and methodology of the IN TOUCH study: a multicenter randomised trial.

BACKGROUND: Although the value of telemonitoring in heart failure patients is increasingly studied, little is known about the value of the separate components of telehealth: ICT guided disease management and telemonitoring. The aim of this study is to investigate the value of telemonitoring added to ICT guided disease management (DM) on the quality and efficiency of care in patients with chronic heart failure (CHF) after a hospitalisation. METHODS/DESIGN: The study is divided in two arms; a control arm (DM) and an intervention arm (DM+TM) in 10 hospitals in the Netherlands. In total 220 patients will be included after worsening of CHF (DM: N = 90, DM+TM: N = 130). Total follow-up will be 9 months. Data will be collected at inclusion and then after 2 weeks, 4.5 and 9 months. The primary endpoint of this study is a composite score of: 1: death from any cause during the follow-up of the study, 2: first readmission for HF and 3: change in quality of life compared to baseline, assessed by the Minnesota Living with Heart failure Questionnaire. The study has started in December 2009 and results are expected in 2012. CONCLUSIONS: The IN TOUCH study is the first to investigate the effect of telemonitoring on top of ICT guided DM on the quality and efficiency of care in patients with worsening HF and will use a composite score as its primary endpoint. TRIAL REGISTRATION: Netherlands Trial Register (NTR): NTR1898.

Ischemic patterns assessed by positron emission tomography predict adverse outcome in patients with idiopathic dilated cardiomyopathy.

BACKGROUND: Although patients with idiopathic dilated cardiomyopathy (DCM) have no coronary artery disease, regional impairment of myocardial perfusion combined with preserved metabolism has been found using positron emission tomography (PET). Our aim was to assess the prognostic relevance of PET-mismatch between stress myocardial perfusion and glucose uptake on clinical outcome in DCM. METHODS: In 24 patients with DCM who underwent both myocardial perfusion and metabolism PET scanning, "mismatch" was assessed and the association with clinical outcome (hospitalization, mortality, and heart transplantation) was investigated. RESULTS: Mismatch was found in 16 patients (66.7%). Univariate analysis showed that the presence of mismatch was associated with adverse outcome (P = 0.03). After adjustment for sex and age, the association remained significant with an adjusted relative risk of 10.4 (95% CI 1.1-103; P = 0.04) for death, heart transplant, or hospitalization. Univariate analysis also showed that a higher extent of mismatch was significantly associated with adverse outcome (P = 0.02). After adjusting for sex and age, the association remained significant with an adjusted relative risk of 6.5 [95% CI 1.2-36; P = 0.03] for death, heart transplantation, or hospitalization. CONCLUSION: PET stress perfusion-metabolism mismatch, indicative for ischemia, is frequently found in DCM patients and related to a poorer outcome.

Myocardial beta-adrenoceptor downregulation in idiopathic dilated cardiomyopathy measured in vivo with PET using the new radioligand (S)-[11C]CGP12388.

PURPOSE: The beta-adrenoceptor (beta-AR) plays an important role in heart failure. Recently, the new tracer (S)-[11C]CGP12388 has been developed. It displays excellent properties for investigation of the cardiac beta-ARs in vivo with positron emission tomography (PET). Furthermore, the simple production method allows its use in a routine clinical setting. The aim of this study was to investigate whether decreased myocardial beta-AR density in patients with idiopathic dilated cardiomyopathy (IDC) can be estimated using (S)-[11C]CGP12388 PET. METHODS: Myocardial beta-AR density was investigated in six patients with IDC and six age-matched healthy controls, using (S)-[11C]CGP12388 PET. RESULTS: Beta-AR densities of 5.4+/-1.3 pmol/g (mean +/- SD) were observed in patients; these values were significantly lower than those observed in healthy controls (8.4+/-1.5 pmol/g, p<0.005). CONCLUSION: This study indicates that PET with (S)-[11C]CGP12388 is applicable for the measurement of myocardial beta-AR density in patients. A highly significant reduction in beta-AR density was found in patients with IDC compared with healthy controls.

PET for evaluation of differential myocardial perfusion dynamics after VEGF gene therapy and laser therapy in end-stage coronary artery disease.

UNLABELLED: The purpose of this study was to appraise the value of PET in the assessment of the effect of supposedly proangiogenic new therapies such as gene therapy with vascular endothelial growth factor (VEGF) gene and endomyocardial laser therapy. METHODS: Thirty-five patients with end-stage coronary artery disease and class III (Canadian Cardiovascular Society) angina were included. Myocardial ischemia was evaluated with dipyridamole PET scanning and exercise tolerance with bicycle ergometry. Ten patients were treated with naked plasmid DNA encoding for human VEGF165 (VEGF) and 12 patients were treated with laser therapy (direct myocardial revascularization [DMR]) using an electromechanical mapping system. Thirteen patients were treated with standard medical therapy (control). RESULTS: In both active treatment groups, angina was reduced in most subjects, except in 2 VEGF and 5 DMR patients. In the control group, no improvement in anginal classification was found, except in 3 subjects. On the PET scan, solely in the VEGF group, the stress perfusion was significantly improved (from 57 +/- 33 to 81 +/- 55 mL/min/100 g; P = 0.031). Furthermore, in the VEGF group, the number of ischemic segments was reduced from 274 +/- 41 to 234 +/- 48 segments (P = 0.004) but not in the DMR group (from 209 +/- 43 to 215 +/- 52 segments) or in the control group (from 218 +/- 18 to 213 +/- 28 segments). Bicycle exercise duration showed slight nonsignificant changes in the VEGF group (from 3.6 +/- 2.0 to 4.6 +/- 2.1 min), in the DMR group (from 5.1 +/- 1.5 to 4.7 +/- 1.3 min), and in the control group (from 3.3 +/- 1.8 to 3.5 +/- 2.3 min). CONCLUSION: PET showed that intramyocardial gene therapy with the human VEGF165 gene in contrast to laser DMR treatment effectively reduces myocardial ischemia.

Comparison of gated PET with MRI for evaluation of left ventricular function in patients with coronary artery disease.

UNLABELLED: The aim of this study was to compare left ventricular (LV) volumes and regional wall motion determined by PET with those determined by the reference technique, cardiovascular MRI. METHODS: LV end-diastolic volume (LVEDV), LV end-systolic volume (LVESV), and LV ejection fraction (LVEF) were measured and regional wall motion was scored in 38 patients with chronic coronary artery disease by both gated (18)F-FDG PET and MRI. A 9-segment model was used for PET and MRI to assess regional wall motion. RESULTS: Good correlations were observed between MRI and gated PET for all parameters (r values ranging from 0.91 to 0.96). With PET, there was a significant but small underestimation of LVEDV and LVEF. Mean +/- SD LVEDV, LVESV, and LVEF for MRI were 131 +/- 57 mL, 91 +/- 12 mL, and 33% +/- 12%, respectively, and those for gated PET were 117 +/- 56 mL, 85 +/- 51 mL, and 30% +/- 11%, respectively. For regional wall motion, an agreement of 85% was found, with a kappa-statistic of 0.79 (95% confidence interval, 0.70-0.89; SE, 0.049). CONCLUSION: LV volumes, LVEF, and regional wall motion can be assessed with gated (18)F-FDG PET and correlate well with these parameters assessed by MRI.