•Temperature rise was measured between acetabular insert and femoral head.•Experiments were conducted with a custom made hip joint friction simulator.•Temperature rise of UHMWPE was theoretically ...calculated.•Theoretical and experimental results were comparable.•Lower temperature rise was measured for VE-UHMWPE than conventional UHMWPE.
Frictional heating of articulating surfaces may influence the rate of wear, fatigue, creep and oxidative degradation of bearing materials. Also temperature rise can damage the surrounding tissue and lubricant around the artificial joint and contributes insert loosening. The objective of this study is to determine temperature rise between sliding surface of vitamin E blended UHMWPE and conventional UHMWPE acetabular component paired with a cobalt–chromium–molybdenum (CoCrMo) femoral component, as a function of sliding time and applied load. Besides the experimental studies, the frictional temperature rise of conventional UHMWPE was theoretically calculated. Frictional measurements of the joints were carried out on a custom made hip joint friction simulator. The diameter of the prostheses was 28mm. Applied static loads were changed from 200N to 1500N. In flexion–extension plane, a simple harmonic oscillatory motion between ±24° was applied to the UHMWPE acetabular component. The period of motion was 1Hz and the tests were run up to 11,000 cycles. Temperature rise in acetabular and femoral component was recorded with embedded thermocouples. Both the experimental temperature rise values and theoretical calculations results were compared and evaluated.
Porous and biodegradable hyaluronic acid (HA) nanogel and their copolymeric forms with sucrose (Suc), HA:Sucrose (HA:Suc) nanogels, were synthesized by employing glycerol diglycidyl ether (GDE) as ...crosslinker with a single step reaction in surfactant-free medium. The size of the nanogels was determined as 150 ± 50 nm in dried state from SEM images and found to increase to about 540 ± 47 nm in DI water measured with DLS measurements. The surface areas of HA and HA:Suc nanogels were measured as 18.07 ± 2.4 and 32.30 ± 6.1 m2/g with porosities of 3.58 ± 1.8, and 9.44 ± 3.1 nm via BET analysis, respectively. The zeta potentials for HA and HA:Suc nanogels were measured as −33 ± 1.4 and − 30 ± 1.2 mV, respectively. The thermal degradation of both types of nanogels revealed similar trends, while hydrolytic degradation of the nanogels was about 22.7 ± 0.2 wt% in 15 days. Both HA and HA:Suc nanogels were stable in blood up to 250 μg/mL concentration with approximately 0.5 ± 0.1% hemolysis ratio and 76 ± 12% blood clotting indices, respectively. Finally, these nanogels were used as a sustained slow-release or long-term delivery system over 2 days for a hydrophobic cancer drug, 3‑((E)‑3‑(4‑hydroxyphenyl)acryloyl)‑2H‑chromen‑2‑on (A#) established by our group. The nanogels successfully delivered the model drug A at 10.43 ± 2.12 mg/g for 2 days.
•Facile synthesis of HA and HA:Suc nanogels in a surfactant free environment with high yield•HA based nanogels with few hundred nm sizes, irregular shaped, mesoporous structure•HA:Suc nanogels as biodegradable, blood compatible and cancer drug delivery device
The aim of this study was to evaluate the feasibility of off-pump coronary artery bypass grafting combined with radiofrequency ablation and to compare outcomes between patients with permanent and ...paroxysmal atrial fibrillation (AF) in terms of restoring sinus rhythm.
Thirty-three patients underwent the combined procedure. Mean age was 62.34 ± 8.20 years; there were 12 female and 21 male patients. Twenty-one patients were diagnosed as permanent AF (group A) and 12 had paroxysmal AF (group B). After the off-pump revascularization patients underwent pulmonary vein ablation. Rhythm was evaluated at discharge and at 6 and 12 months’ follow-up. Patients in stable sinus rhythm underwent transthoracic echocardiographic examination to evaluate atrial contractility at 6 and 12 months.
There was no operative mortality or major complications. The mean ablation time was 11 ± 3.4 minutes, including multiple applications. At the end of the procedure 84.5% of patients were free of AF. Sinus rhythm was established in 56% (group A, 52%; group B, 58.3%), 70.5% (group A, 58%; group B, 83.3%), and 71% (group A, 59%; group B, 83.3%) of patients at discharge and at 6 and 12 months, respectively (
p = 0.249). Biatrial contractility was detected in 71% of group A and 76% of group B patients at 6 months’ follow-up. More patients in group A returned to AF during follow-up when compared with group B (
p = 0.016). Female sex (odds ratio, 2.1), chronic lung disease (odds ratio, 1.40), left ventricular disfunction (
p = 0.016), and hypertension (odds ratio, 2.57) emerged as risk factors for AF recurrence after ablation.
Concomitant off-pump coronary artery bypass grafting and bipolar radiofrequency ablation was safe and effective. These patients should be considered for adjunctive treatment at the time of off-pump revascularization.
Objective: The aim of this study was to assess the feasibility and effectiveness of irrigated radiofrequency (RF) modified Maze procedure through a port access approach during mitral valve surgery ...and evaluate early and mid-term results. Material and method: During a 16 months time period, 67 patients with chronic atrial fibrillation (AF) eligible for port access mitral valve surgery were randomly assigned to either Group A, in which they underwent a combined procedure (N=33) or Group B, in which a valve procedure alone was performed (N=34). Both groups were similar in terms of age, sex, valve pathology, duration of AF left atrial diameter and left ventricle function (P>0.05). Four had undergone previous operations. Results: Median follow-up was 10 months for both groups, 95% CI (9.18–10.8). One patient in each group died early postoperatively (3 and 2.9%). Two patients required reoperation for bleeding, one in each group (3 and 2.9%). There were two conversions to right thoracotomy. In Group A, freedom from AF was 100% at the end of the operation (76% sinus, 24% pacemaker) Six and twelve months freedom from AF was 87.2 and 93.6%, respectively. In Group B, freedom from AF at the end of operation was 41%. At the end of 6 and 12 months, freedom from AF was 9.4% (P=0.0001). One patient in Group A required a permanent pacemaker (3%). During follow-up, one patient in Group A died of non-cardiac causes (3%). In Group B, there were two late deaths: one cardiac (2.9%) and one neurologic (2.9%). There were no thromboembolic events detected in Group A during follow-up, whereas two patients in Group B suffered this complication (6%, P=0.081). At 12 months, functional capacity had improved for patients in both groups (P<0.0001). Conclusion: The combination of mitral valve surgery and irrigated RF Maze procedure was safe and efficient through a port access approach. There were no procedure related complications like esophageal or coronary artery injury. Early and mid-term results were favourable with 93.6% of patients free of AF at 1 year in comparison to the 9.4% of the control group. The data is not sufficient to reach any conclusions in terms of thromboembolic rates, despite favourable results for the RF Maze group. Nevertheless, in terms of feasibilty, sinus rhythm restoration and overall outcome, early results are encouraging and we advocate the use of the combined procedure through a port access approach.
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