Modeling and Experiments of an Annular Multi-Channel Magnetorheological Valve

With the increasing number of cars, the demand for vehicle maintenance lifts is also increasing. The hydraulic valve is one of its core components, but there are problems with it such as inaccurate positioning and failure. In order to improve the service performance of vehicle maintenance elevators, a novel annular multi-channel magnetorheological (MR) valve structure was creatively proposed based on intelligent material MR fluid (MRF), and its magnetic circuit was designed. The influence of current, damping gap and coil turns on the pressure drop performance of the annular multi-channel MR valve was numerically studied and compared with ordinary type magnetorheological valve pressure drop performance through contrast and analysis. The influence of different loads and currents on the pressure drop performance of annular multi-channel magnetorheological valve was verified by experiments, and the reliability of numerical analysis results was verified. The results show that the single winding excitation coil is 321 to meet the demand. The pressure drop performance of the annular multi-channel magnetorheological valve is 5.6 times that of the ordinary magnetorheological valve. The load has little influence on the regulating range and performance of pressure drop of the MR valve. Compared with the common type, the pressure drop performance of the annular multi-channel MR Valve is improved by 3.7 times, which is basically consistent with the simulation results.

Reconsidering Ventriculoperitoneal Shunt Surgery and Postoperative Shunt Valve Pressure Adjustment: Our Approaches Learned From Past Challenges and Failures

Treatment for idiopathic normal pressure hydrocephalus (iNPH) continues to develop. Although ventriculoperitoneal shunt surgery has a long history and is one of the most established neurosurgeries, in the 1970s, the improvement rate of iNPH triad symptoms was poor and the risks related to shunt implantation were high. This led experts to question the surgical indication for iNPH and, over the next 20 years, cerebrospinal fluid (CSF) shunt surgery for iNPH fell out of favor and was rarely performed. However, the development of programmable-pressure shunt valve devices has reduced the major complications associated with the CSF drainage volume and appears to have increased shunt effectiveness. In addition, the development of support devices for the placement of ventricular catheters including preoperative virtual simulation and navigation systems has increased the certainty of ventriculoperitoneal shunt surgery. Secure shunt implantation is the most important prognostic indicator, but ensuring optimal initial valve pressure is also important. Since over-drainage is most likely to occur in the month after shunting, it is generally believed that a high initial setting of shunt valve pressure is the safest option. However, this does not always result in sufficient improvement of the symptoms in the early period after shunting. In fact, evidence suggests that setting the optimal valve pressure early after shunting may cause symptoms to improve earlier. This leads to improved quality of life and better long-term independent living expectations. However, in iNPH patients, the remaining symptoms may worsen again after several years, even when there is initial improvement due to setting the optimal valve pressure early after shunting. Because of the possibility of insufficient CSF drainage, the valve pressure should be reduced by one step (2–4 cmH2O) after 6 months to a year after shunting to maximize symptom improvement. After the valve pressure is reduced, a head CT scan is advised a month later.

Case Report: Leaflet Thrombosis After Transcatheter Aortic Valve Replacement With Worsening Heart Failure—A Successful Resolution Using Non-vitamin K Antagonist Oral Anti-coagulant

Background: Transcatheter aortic valve replacement (TAVR) is indicated for treating symptomatic severe aortic valve stenosis (AS) with intermediate-to-high surgical risks. Few reports are available on managing leaflet thrombosis after TAVR with worsening heart failure.Case Summary: A 77-year-old man with severe AS and coronary artery disease (CAD) received a successful TAVR with Edwards Sapien 3 valve. A year later, the patient developed a worsening heart failure with pulmonary edema, new-onset atrial fibrillation (Af), an increase in mean trans-aortic valve pressure gradient to 48 mmHg, worsening mitral regurgitation (MR), and pulmonary hypertension (PH). The response of the patient to intravenous diuretics and inotropic treatments was poor. Multi-slice CT (MDCT) revealed hypo-attenuated thrombus and thickened transcatheter heart valve leaflets. A non-vitamin K antagonist oral anti-coagulant (NOAC) was added to treat the new-onset Af and leaflet thrombosis on top of the con-current single antiplatelet for CAD. A series of follow-up echocardiograms showed a progressive decrease in trans-aortic valve pressure gradient to 17 mmHg and reductions in MR and PH. Three months after the NOAC treatment, MDCT revealed the resolution of hypo-attenuated thrombus and thickened leaflets. Symptoms of heart failure were also improved gradually.Discussion: Worsening heart failure or an increase in trans-aortic valve pressure gradient after TAVR warranted further MDCT studies. Leaflet thrombosis can be resolved after using NOAC as in our present case.

Immediate Post-Procedural and Discharge Assessment of Mitral Valve Function Following Transcatheter Edge-to-Edge Mitral Valve Repair: Correlation and Association with Outcomes

The correlation between residual mitral regurgitation (rMR) grade or mitral valve pressure gradient (MVPG), at transcatheter edge-to-edge mitral valve repair (TEEMr) completion and at discharge, is unknown. Furthermore, there is disagreement regarding rMR grade or MVPG from which prognosis diverts. We retrospectively studied 82 patients that underwent TEEMr. We tested the correlation between rMR or MVPG and evaluated their association, with outcomes. Moderate or less rMR (rMR ≤ 2) at TEEMr completion was associated with improved survival, whereas mild or less rMR (rMR ≤ 1) was not. Patients with rMR ≤ 1 at discharge demonstrated a longer time of survival, of first heart failure hospitalization and of both. The correlation for both rMR grade (r = 0.5, p < 0.001) and MVPG (r = 0.51, p < 0.001), between TEEMr completion and discharge, was moderate. MR ≤ 2 at TMEER completion was the strongest predictor for survival (HR 0.08, p < 0.001) whereas rMR ≤ 1 at discharge was independently associated with a lower risk of the combined endpoint (HR 4.17, p = 0.012). MVPG was not associated with adverse events. We conclude that the assessments for rMR grade and MVPG, at the completion of TEEMr and at discharge, should be distinctly reported. Improved outcome is expected with rMR ≤ 2 at TEEMr completion and rMR ≤ 1 at discharge. Higher MVPG is not associated with unfavorable outcomes.

Long-Term survival and functional status in patients with elevated mitral valve pressure gradient after transcatheter mitral valve repair

Background A growing number of patients are currently treated for severe mitral regurgitation (MR) using a transcatheter mitral valve repair (TMVr). In clinical routine, the potential risk of elevated post-procedural mitral valve pressure gradient (MPG) may prohibit optimal MR reduction driven by the avoidance of additional clip implantations. Thus, the unfavorable impact on survival and functional outcome of increased MPG in patients undergoing TMVr is currently debatable. Methods In this single-center, prospective study, survival and functional outcome of 780 consecutive patients with severe MR undergoing TMVr between September 2008 and January 2020 were investigated. After exclusion of patients with unsuccessful procedure and those lost to follow-up, data of 676 patients with a median follow-up time of 5.26 (5.11, 5.51) years were analyzed. MPG was determined by transthoracic echocardiography at discharge and considered elevated in excess of 4.5 mmHg. Kaplan-Meier analysis as well as multivariable Cox regression models were performed for the impact on elevated MPG on 5-year outcomes for the subgroups of functional MR (FMR) and degenerative MR (DMR). The primary outcome measure was a combined endpoint of death or rehospitalization for congestive heart failure. Results Among 676 patients undergoing TMVr (mean age 74.6±8.5 years, 59.0% male, median STS Score 3.9 [interquartile range 2.5; 6.0]), 179 (26.4%) patients had elevated MPG &gt;4.5 mmHg. FMR was present in 426 (63.0%) patients. In the overall patient cohort, Kaplan-Meier and Cox Regression analyses could not demonstrate significant differences for the combined endpoint (p=0.99). In contrast, subgroup analysis according to MR etiology indicated a significant adverse influence of elevated MPG on the combined endpoint as well as functional outcome in patients with DMR, but not with FMR (Figure 1). After adjustment, multivariate Cox Regression analysis showed an inferior prognosis in patients with DMR and elevated MVPG &gt;4.5 mmHg (hazard ratio 1.79 [1.17, 2.72], p=0.0069, Figure 2). Conclusions TMVr-patients with DMR and measurable elevated post-procedural MVPG face an inferior prognosis and reduced functional outcomes compared to patients with FMR. FUNDunding Acknowledgement Type of funding sources: None. Figure 1 Figure 2

Parkinsonism secondary to ventriculoperitoneal shunt in a patient with hydrocephalus

Background: Parkinsonism secondary to the treatment of obstructive hydrocephalus due to stenosis of the cerebral aqueduct, with implantation of a ventricular peritoneal (VP) shunt is a rare complication, still poorly described and disseminated in the literature. Case Description: A 38-year-old male presented a history of moderate-intensity daily headache, which deteriorated 2 months before admission, with no changes in the neurological examination. Magnetic resonance imaging showed hypertensive hydrocephalus associated with cerebral aqueduct stenosis. A VP shunt was performed, an adjustable pressure valve was successfully inserted, and he was discharged asymptomatic. However, months later, he progressed with important symptoms of hypo- and hyper-drainage, which persisted after valve pressure adjustments and even its exchange, culminating into an endoscopic third ventriculostomy (ETV). But soon after, severe Parkinsonian syndrome appeared. Therapy with levodopa and bromocriptine was initiated, revealing a slow response initially but good evolution within 6 months. At present, he presents low-intensity residual tremor, which is well controlled with medications, and has regained independence for daily activities, with minimal motor limitation and no cognitive changes. Conclusion: There is still no mechanism that explains the occurrence of Parkinsonian syndrome in these cases. It is suggested that the rostral portion of the midbrain was injured due to abrupt changes in the transtentorial gradient pressure after the ventricular shunt, along with various adjustments in the valve pressure. ETV and early introduction of levodopa therapy in patients who developed postventriculoperitoneal shunt Parkinsonism seems to be the most effective combination, with satisfactory clinical response in the medium/long term.

Early outcomes of mitral valve replacement with a mechanical prosthesis for rheumatic mitral valve disease.

Objectives: To study the early outcomes of mitral valve replacement with a mechanical prosthesis is patients with rheumatic mitral valvular disease. Study Design: Retrospective Observational study. Setting: Punjab Institute of Cardiology, Lahore and Rawalpindi Institute of Cardiology, Rawalpindi. Period: From August 2014 to August 2017. Material & Methods: Consecutive patients who underwent mitral valve replacement for a rheumatic pathology were included in the study. Patients undergoing a redo surgery, those with concomitant aortic valve intervention, coronary artery bypass grafting and emergency procedures were excluded from the study. Results: Of the 104 patients included in the study, 58 (56.2%) were female patients. The mean age of the patients was 35 ± 12.36 years (median 33 years). Sixty (58.5%) had hypertension and 22 (21.28%) had diabetes. Mitral valve stenosis was the main pathology in 84 (81.25%). Severe pulmonary hypertension was recorded in 15 (15%) patients. The mean preoperative Tricuspid Valve Pressure Gradient (TVPG) was 55.33 ± 18.35 mmHg. The mean cross clamp time was 45.33 ± 12.32 minutes. The postoperative tricuspid valve pressure gradient came down to 31.5 ± 12.21 mmHg. No patients had acute renal injury, pulmonary complications or re-exploration for bleeding. Perioperative mortality was 4 (3.75%). Conclusion: Rheumatic valvular disease is still prevalent in our part of the world. Most of the patients with rheumatic heart disease will end up with replacement of the valve. Replacement with a mechanical prosthesis has favorable early outcomes.