Valve Type Research Articles

Transcatheter Aortic Valve Replacement in Bicuspid Versus Tricuspid Aortic Valve Stenosis: Meta-Analysis and Systemic Review

Because of its anatomic and procedural complexities, bicuspid aortic valve (BAV) has been excluded from previous trials investigating transcatheter aortic valve replacement (TAVR). We aimed to compare the clinical outcomes of TAVR in BAV and tricuspid aortic valve patients. We searched the databases systematically from inception until March 2023 for studies that reported the outcomes of TAVR in BAV and tricuspid aortic valve patients. The primary focus was all-cause mortality at 1year. Additional outcomes included outcomes at 30-day follow-up. Secondary and subgroup analyses were performed on propensity-matched patients, patients at low surgical risk, and based on the type of transcatheter valve type. We included 30 studies with a total of 193,274 patients who underwent TAVR, of which 14,353 patients had BAV stenosis. The rate of 1-year mortality was lower in the BAV group compared with the tricuspid group with the results reaching statistical significance (odds ratio [OR] 0.86, 95% confidence interval [CI] 0.75 to 0.98, p=0.02). The rate of 30-day stroke, however, was higher in patients with BAV who underwent TAVR (OR 1.24, 95% CI 1.08 to 1.43, p<0.05). Other 30-day clinical outcomes were similar between the 2 groups. Similar outcomes were observed in secondary analysis of matched populations with less mortality and higher rate of stroke in patients with BAV (OR 0.84, 95% CI 0.72 to 0.96, p=0.01, and OR 1.38, 95% CI 1.09 to 1.75, p<0.05, respectively). Comparing the outcomes for self-expandable and balloon-expandable valves resulted in similar results. Subgroup analysis of low-surgical-risk patients similarly showed lower 1-year mortality in patients with BAV (OR 0.67, 95% CI 0.50 to 0.91, p=0.01), without difference in 30-day stroke between the 2 groups (OR 1.24, 95% CI 0.83 to 1.88, p=0.30). In conclusion, this report indicates that TAVR is safe and feasible in patients with BAV, including patients at low surgical risk. The higher rate of 30-day stroke, however, warrants caution when pursuing TAVR in this population. More studies, specifically randomized trials, are still warranted to further assess the safety and the long-term outcomes in this group.

Scientific Evolution of Artificial Heart Valves: A Narrative Review.

Cardiovascular disorders have always been the top contributors to the number of mortality occurring worldwide. But the last few decades have seen a drop in those numbers as the lives of millions of people have been saved due to ground-breaking advances in both therapeutic and surgical treatment modalities. Achieving this level of scientific glory in cardiology was a challenging feat. The credit goes to the scientists and physicians of the previous century who, despite their time's technological limitations, made discoveries and laid a solid foundation for modern medicine. Valvular complications are a major part of the global burden of cardiac diseases. The ongoing development of heart valve replacements remains a fascinating subject, as it continues to progress. Valve replacements comprise either mechanical heart valves or bioprosthetic heart valves. Both types of valves have their merits and demerits; their usage depends mostly on individual patient requirements. This article aims to review the evolution of the implantation of heart valves, and it is the objective of this article to give credit to scientists and physicians for their contributions. The article highlights the research gaps in finding more durable materials and the scope of further research in creating a heart valve that can be universally used for better patient outcomes.

Conduction Disturbance After Transcatheter Aortic Valve Implantation With Self- or Balloon-Expandable Valve According to the Implantation Depth

Membranous septum (MS) length, in conjunction with implantation depth (ID), is known as a determinant of conduction disturbance (CD) after transcatheter aortic valve implantation (TAVI). However, its impact might be dissimilar among valve types because each valve has a different platform. This study sought to investigate the different impacts of ID and MS length on the new-onset CD between ACURATE neo and SAPIEN 3. This study included patients without a previous permanent pacemaker implantation who underwent TAVI with ACURATE neo and SAPIEN 3 and divided them into 2 groups based on the ID according to MS length (deep and shallow implantation group). Deep implantation was defined as transcatheter heart valve implantation deeper than MS length. The primary endpoint was new-onset CD (new permanent pacemaker implantation or new-onset complete left bundle branch block). A total of 688 patients (deep implantation: n=373, shallow implantation: n=315) were identified as a study cohort. New-onset CD developed more frequently in the deep implantation group (16.6% vs 7.0%; p=0.0001). Deep implantation was revealed as a predictor of new-onset CD. Moreover, deep implantation was significantly associated with new-onset CD after SAPIEN 3 implantation but not after ACURATE neo. Among patients with MS shorter than 2mm, ACURATE neo was superior in terms of avoiding new-onset CD. In conclusion, the deep implantation was associated with new-onset CD after TAVI with SAPIEN 3 but not with ACURATE neo. These results may impact device selection in patients with a preexisting high risk of CD.

Electrophysiological evaluation following development of new and persistent left bundle branch block after transcatheter aortic valve replacement: A single center pilot study.

New and persistent left bundle branch block (NP-LBBB) following Transcatheter Aortic Valve Replacement (TAVR) is an ongoing concern with incidence ranging from as low as 4% to up to 65% (varying for different types of valves). Such patients are at risk of developing high-grade atrioventricular block (HAVB) warranting permanent pacemaker (PPM) implantation. However, currently, there are no consensus guidelines or large prospective studies to risk stratify these patients for safer discharge after TAVR. To provide insight from a single center study on using modified electrophysiology (EP) study to risk stratify post-TAVR patients to outpatient monitoring for low-risk versus pacemaker implantation for high-risk patients. Between June 2020 and March 2023, all patients who underwent a TAVR procedure (324 patients) at our institution were screened for development of NP-LBBB post-operatively. Out of 26 patients who developed NP-LBBB, after a pre-specified period of observation, 18 patients were deemed eligible for a modified EP study to assess His-Ventricular (HV) interval. 11 out of 18 patients (61.1%) had normal HV interval (HV<55ms). Three out of 18 patients (16.7%) had HV prolongation (55ms<HV<70ms) without significant HV prolongation (defined as an increase in HV interval>30%) with intra-procedural procainamide challenge. Four out of 18 patients (22.2%) had significant HV prolongation (HV>70ms) warranting PPM implantation based on a multidisciplinary approach and shared decision-making with the patients. Total of 50% of patients discharged with PPM (two out of four patients) were noted to be pacemaker dependent based on serial device interrogations. All patients who did not receive PPM were discharged with ambulatory monitoring with 30-day event monitor and did not develop HAVB on serial follow-up. Normal HV interval up to 55ms on modified EP study after TAVR and development of NP-LBBB can be utilized as a threshold for risk stratification to facilitate safe discharge. The optimal upper limit of HV interval threshold remains unclear in determining appropriate candidacy for PPM.

Investigation of factors determining haemodynamic relevance of leaflet thrombosis after transcatheter aortic valve implantation.

To determine the conditions under which early hypoattenuated leaflet thickening (HALT) after transcatheter aortic valve implantation (TAVI) becomes haemodynamically relevant. The study included 100 patients (age: 81.5 ± 5.5 years; female 63%), thereof 50 patients with HALT. After anonymization and randomization, blinded readers measured maximum thrombus thickness per prosthesis (MT_pr) and movement restriction (MR_pr) on electrocardiogram (ECG)-gated whole heart cycle computed tomography angiography. These measurements were compared with echocardiographic mean pressure gradient (mPG), its increase from baseline (ΔmPG), and Doppler velocity index (DVI). Haemodynamic valve deterioration (HVD) was defined as mPG > 20 mmHg. Age, body mass index, valve type, valve size, left ventricular ejection fraction, and atrial fibrillation were considered as influencing factors. Multiple regression analysis revealed that only valve size (P = 0.001) and MT_pr (P = 0.02) had a significant influence on mPG. In an interaction model, valve size moderated the effect of MT_pr on mPG significantly (P = 0.004). Sub-group analysis stratified by valve sizes showed a strong correlation between MT_pr and echocardiographic parameters for 23 mm valves (mPG: r = 0.57, ΔmPG: r = 0.68, DVI: r = 0.55, each with P < 0.001), but neither for 26 nor 29 mm valves (r < 0.2, P > 0.2 for all correlations). Six of seven prostheses with HVD had a 23 mm valve diameter, while one had 29 mm (P = 0.02). Early HALT rarely causes significant mPG increase. Our study shows that valve size is a key factor influencing the haemodynamic impact of HALT. In small valve sizes, mPG is more likely to increase. Our study is the first to offer in vivo evidence supporting previous in vitro findings on this topic.

Study on the performance characteristics and failure analysis of exhaust valves

Abstract Exhaust valves are a type of valve that can commonly be found in the top section of the cylinder block in an engine. When failures occur on the exhaust valve, the engine has a high possibility to result engine failure or breakdown. This will affect the user where the user requires to spend a huge amount on repairing costs or engine replacement. Thus, this research aims to investigate the effect of the exhaust valve’s material on its performance and identify the appropriate material which could increase its fatigue life in a four-stroke internal combustion diesel engine. A three-dimension (3D) Computer-aided design model of the exhaust valve was generated by using SOLIDWORKS and undergo static structural analysis as well as thermal analysis. The measure variables are von-mises stress, total deformation, temperature, total heat flux and directional heat flux by using ANSYS Finite Element Analysis. Stainless steel 304 alloy and Aluminium-Silicon Carbide (Al-Sic) materials are the manipulated variable that was applied to the 3D CAD model exhaust valve to undergo all the analyses. Before performing all the analyses, the appropriate mesh method and mesh sizing was identified by referring to the mesh metrics spectrum and performing a mesh independence test. The results from the analysis were collected and tabulated for comparison and discussion purposes. From the analysis, the maximal thermal stress was determined in the valve stem region. By appointing Stainless Steel 304 alloy on the exhaust valve, the durability and the fatigue life are improved as the material can achieve a smaller value of temperature distribution, total heat flux, total deformation, and higher von-mises stress. This research provided a better understanding of the effect of an exhaust valve material on its performance characteristic.

Transcatheter aortic valve implantation in patients with extra-small aortic annuli.

A small aortic annulus (SAA) is a risk factor for prosthesis-patient mismatch (PPM) in patients undergoing surgical or transcatheter aortic valve implantation (TAVI). Data regarding TAVI in patients with extra-SAA are scarce. The aim of this study was to analyse the safety and efficacy of TAVI in patients with extra-SAA. A multicentre registry study including patients with extra-SAA (defined as an aortic annulus area <280 mm2 and/or perimeter <60 mm) undergoing TAVI was established. Primary efficacy and safety endpoints were defined as device success and early safety at 30 days, respectively, using the Valve Academic Research Consortium-3 criteria, and were analysed according to valve type: self-expanding (SEV) versus balloon-expandable (BEV). A total of 150 patients were included, of which 139 (92.7%) were women, and 110 (73.3%) received an SEV. Intraprocedural technical success was 91.3%, with a higher rate in patients receiving an SEV (96.4% vs 77.5% with BEV; p=0.001). Overall, 30-day device success was 81.3%, (85.5% with SEV vs 70.0% with BEV; p=0.032). The primary safety endpoint occurred in 72.0% of patients (with no difference between groups; p=0.118). Severe PPM occurred in 12% (9.0% with SEV and 24.0% with BEV; p=0.039), with no impact on all-cause mortality, cardiovascular mortality, or heart failure readmission at 2-year follow-up. TAVI is a safe and feasible treatment in patients with extra-SAA with a high rate of technical success. The use of SEV was associated with a lower rate of intraprocedural complications, higher device success at 30 days and better haemodynamic outcomes compared to BEV.

Nonprogrammable Shunts for Communicating Hydrocephalus and Three-Dimensional Volumetry: A Retrospective Analysis

Although the use of different types of valves have been extensively studied in shunt surgeries for communicating hydrocephalus (cHC), a consensus about the valve type remains absent. The objective of this study is to evaluate our results with the primary placement of non-programmable valves (NPV) for this indication. We retrospectively analyzed all first NPV implanted between 2014-2020 for cHC. We studied the revision rate, clinical outcome described by modified Ranking Scale (mRS) and radiological evolution using Evans index (EI) and ventricular volumes 3D-semiautomatic segmentation (vv-3DSAS). Forty-one patients were shunted for post-hemorrhagic (61%), post-traumatic (24.4%) and tumoral (14.6%) hydrocephalus (HC). Mean age was 65 years (range 25-89yrs). Overall, 59 procedures were performed including 18 revision surgeries in 12 patients (29.3%). Underlying reason for first shunt revision were valve type related: valve dysfunction, overdrainage, underdrainage and non-valve type related: malpositioning, infection, shunt migration. The shunt-related revision rate was 17.1%. Twenty-eight patients (68.3%) had an mRS improvement of 1 or more points. We found a good correlation between ventricle volumes (VV) and EI and a significant reduction in VV measured by EI and vv-3DSAS was observed. However, the mRS improvement was not correlated with a reduction of ventricle volumes. Overall, our results in terms of shunt revisions as well as clinical and radiological evolution are comparable with the literature for NPV. vv-3DSAS can be used and could be useful to detect small changes in VV in patients with cHC.

Effect of acute CORticosteroids on conduction defects after Transcatheter Aortic Valve Implantation: the CORTAVI study.

Conduction abnormalities, requiring a permanent pacemaker (PPM), are the most common electrical complications after transcatheter aortic valve implantation (TAVI). The exact mechanism for conduction system defects is not yet clear. The local inflammatory process and edema are thought to play a role in the development of electrical disorders. Corticosteroids are effective anti-inflammatory and antiedematous agents. We aim to investigate the potential protective effect of corticosteroids on conduction defects after TAVI. This is a retrospective study of a single center. We analyzed 96 patients treated with TAVI. Thirty-two patients received oral prednisone 50 mg for 5 days after the procedure. This population was compared with the control group. All patients were followed up after 2 years. Of the 96 patients included, 32 (34%) were exposed to glucocorticoids after TAVI. No differences in age, preexisting right bundle branch block or left bundle branch block, or valve type were seen among patients exposed to glucocorticoids versus those who were unexposed. We observed no significant differences between the two groups in the overall frequency of new PPM implantations during hospitalization (12% vs. 17%, P = 0.76). The incidence of atrioventricular block (AVB) (STx 9% vs. non-STx 9%, P = 0.89), right bundle branch block (STx 6% vs. non-STx 11%, P = 0.71), and left bundle branch block (STx 34% vs. non-STx 31%, P = 0.9) was not significantly different between the STx and non-STx groups. At 2 years after TAVI, none of the patients had implanted PPM or had severe arrhythmias documented by 24-h Holter ECG or cardiac examination. Oral prednisone treatment does not appear to significantly reduce the incidence of AVB requiring acute PPM implantation after TAVI.

Prognostic implications of ultra-short heart rate variability indices in hospitalized patients with infective endocarditis.

Infective endocarditis (IE) is a disease that poses a serious health risk. It is important to identify high-risk patients early in the course of their treatment. In the current study, we evaluated the prognostic value of ultra-short heart-rate variability (HRV), an index of vagal nerve activity, in IE. Retrospective analysis was performed on adult patients admitted to a tertiary hospital due to IE. A logistic regression (LR) was used to determine whether clinical, laboratory, and HRV parameters were predictive of specific clinical features (valve type, staphylococcal infection) or severe short-term complications (cardiac, metastatic infection, and death). The accuracy of the model was evaluated through the measurement of the area under the curve (AUC) of the receiver operating characteristic curve (ROC). An analysis of survival was conducted using Cox regression. A number of HRV indices were calculated, including the standard deviation of normal heart-beat intervals (SDNN) and the root mean square of successive differences (RMSSD). 75 patients, aged 60.3(±18.6) years old, were examined. When compared with published age- and gender-adjusted HRV norms, SDNN and RMSSD were found to be relatively low in our cohort (75%-76% lower than the median; 33%-41% lower than the 2nd percentile). 26(34.6%) patients developed a metastatic infection, with RMSSD<7.03ms (adjusted odds ratio (aOR) 9.340, p = 0.002), incorporated in a multivariate LR model (AUC 0.833). Furthermore, 27(36.0%) patients were diagnosed with Staphylococcus IE, with SDNN<4.92ms (aOR 5.235, p = 0.004), a major component of the multivariate LR model (AUC 0.741). Multivariate Cox regression survival model, included RMSSD (HR 1.008, p = 0.012). SDNN, and particularly RMSSD, derived from ultra-short ECG recordings, may provide prognostic information about patients presenting with IE.

Prediction of test results to determine the hydraulic resistance coefficient of an axially symmetrical check valve

The urgency of the paper is determined by the necessity to predict the results of tests for determining the coefficient of hydraulic resistance of axially symmetrical check valve DN 100-600 with operating pressure up to 20 MPa and operating temperature from plus 50C to plus 3500C according to TS 6981-254-08847871-07. This paper suggests to reduce the volume of tests by excluding the tests for intermediate samples of valves (DN 100, DN125, DN 200, DN 300, DN 500, DN 600) situated in DN between the valve type models (DN 100, DN 175, DN 400) and replaced the tests by calculations in the programme module ANSYS CFX of the calculation complex ANSYS. The results of the tests for determining the coefficient of hydraulic resistance are given. An estimate of hydraulic resistance coefficient values is offered and recommendations for its determination are given. The experimental determination of hydraulic characteristics was carried out in the region of quadratic resistance and in absence of cavitation (the tests were done on water). The region of quadratic resistance comes at Reynolds numbers Re ≥ 2 × 104 for check valve of nominal diameters DN ≤ 250. The region of quadratic resistance ReKB is determined in the process of experimental determination of drag and flow capacity factors for valves of nominal diameters DN ≥ 250. The procedure of determination of ReKB is described in 7.2.3 of GOST 55508-2013. These test results for determination of hydraulic resistance coefficient for valves DN 150, DN 175, DN 400 according to TU 6981-254-08847871-07 can be used when developing acceptance test programs to set the number of tested samples according to the design features and number of versions of check valves (DN 100, DN125, DN 200, DN 300, DN 500, DN 600), replacing the testing by calculation.

Influence of cusp morphology and sex on quantitative valve composition in severe aortic stenosis.

Aortic stenosis is characterized by fibrosis and calcification of the valve, with a higher proportion of fibrosis observed in women. Stenotic bicuspid aortic valves progress more rapidly than tricuspid valves, which may also influence the relative composition of the valve. We aimed to investigate the influence of cusp morphology on quantitative aortic valve composition quantified from contrast-enhanced computed tomography angiography in severe aortic stenosis. Patients undergoing transcatheter aortic valve implantation with bicuspid and tricuspid valves were propensity matched 1:1 by age, sex, and comorbidities. Computed tomography angiograms were analysed using semi-automated software to quantify the fibrotic and calcific scores (volume/valve annular area) and the fibro-calcific ratio (fibrotic score/calcific score). The study population (n = 140) was elderly (76 ± 10 years, 62% male) and had a peak aortic jet velocity of 4.1 ± 0.7 m/s. Compared with those with tricuspid valves (n = 70), patients with bicuspid valves (n = 70) had higher fibrotic scores [204 (interquartile range 118-267) vs. 144 (99-208) mm3/cm2, P = 0.006] with similar calcific scores (P = 0.614). Women had greater fibrotic scores than men in bicuspid [224 (181-307) vs. 169 (109-247) mm3/cm2, P = 0.042] but not tricuspid valves (P = 0.232). Men had greater calcific scores than women in both bicuspid [203 (124-355) vs. 130 (70-182) mm3/cm2, P = 0.008] and tricuspid [177 (136-249) vs. 100 (62-150) mm3/cm2, P = 0.004] valves. Among both valve types, women had a greater fibro-calcific ratio compared with men [tricuspid 1.86 (0.94-2.56) vs. 0.86 (0.54-1.24), P = 0.001 and bicuspid 1.78 (1.21-2.90) vs. 0.74 (0.44-1.53), P = 0.001]. In severe aortic stenosis, bicuspid valves have proportionately more fibrosis than tricuspid valves, especially in women.

Model comparison and effect of flow and accessories on the pressure drop of the unit ff-df-270/el of Universidad de Cartagena

The effect of flow variation on the theoretical calculation of pressure drop in pipes with fittings in the unit FF-DF-270/EL of the Universidad de Cartagena was studied, determining the coefficient of minor losses (Kf) caused by 45° and 90° elbows, and three types of valves, using water as the process fluid. The flow rate (Q) was varied, using a valve, between 24, 20, 16, 12 L/min. Darcy's and Bernoulli's theorem methods were used to evaluate friction losses. Were found minimum error percentages of 0.04% and maximum 8.16%; loss coefficients adjusted by minimum squares were obtained with R2 of 0.999, comparing these Kf with the values reported in the plant manual and different authors. It was shown experimentally that the loss coefficient depends on each fitting, allowing the calculation of the theoretical pressure drop and comparing it with the experimental pressure drop, demonstrating that as the flow increases, an increase in pressure drop is generated. With the methodology applied in this research, the aim is to optimize pressure drop tests with fittings, and identify the characteristics of the pipe to obtain an optimum lower loss coefficient value.

Transforming Droplets into Liquid Films in Nanochannels under Rotating Electric Fields Studied by Molecular Dynamics.

It is first proposed to use a rotating electric field to stretch a droplet into a liquid film pinned to the insulated channel inner wall as a new type of active liquid valve. The molecular dynamics (MD) simulations are performed to prove that droplets in nanochannels can be stretched and expanded into closed liquid films under the action of rotating electric fields. The variations of the liquid cross-sectional area and droplet surface energy with time are calculated. The liquid film formation occurs mainly through two modes: gradual expansion and liquid column rotation. In most cases, increasing the electric field strength and angular frequency favors liquid film closing. At higher angular frequencies, decreasing the angular interval favors liquid film closing. The opposite is true at lower angular frequencies. The process of closing the hole-containing liquid film, which has formed a dynamic equilibrium, is a surface energy increase process, which requires greater electric field strength and angular frequency.

Correlation of Clinical Outcomes with the Prominent Indication of Transcatheter Paravalvular Leak Closure: A Multicenter Experience.

A paravalvular leak (PVL) is a complication following valve replacement, which may lead to heart failure and hemolysis. The aim of this study is to investigate whether the clinical outcome after transcatheter PVL closure differs according to the prominent indication of the procedure (symptoms of heart failure or hemolysis). The data of consecutive patients who had transcatheter treatment for PVL between July 2011 and September 2022 in five Greek centers were analyzed. The primary endpoint was the technical, and clinical success rates with regards to the prominent indication of paravalvular leak closure. The secondary endpoints included the evaluation and comparison of the clinical and technical success in relation to the type of valve that was treated (aortic or mitral) as well as the survival analysis in relation to the closure indication and type of valve that was treated. In total, 60 patients were retrospectively studied (39% men, mean age 69.5 ± 11 years). Regarding the primary outcomes, the technical success in patients mainly suffering from hemolysis was 86.1%, while in those presenting heart failure it was 95.8%, p = 0.387. Furthermore, the clinical success was 72.2% and 87.5% among hemolysis and heart failure patients, respectively, p = 0.210. During the follow-up period, the two-year survival rates were significantly better for patients treated for the aortic valve (78.94%) compared to those in the mitral position (48.78%), p = 0.014. In total, 25 patients died (41.7%) during 24 months of follow-up. Transcatheter paravalvular leak closure can be performed with high technical and clinical success rates without any difference according to the prominent indication of closure.

The first clinical data of the SAPIEN 3 aortic valve in the treatment of aortic stenosis in China.

Data on outcomes following transcatheter aortic valve replacement with SAPIEN 3 in China is limited as it was approved by the National Medical Products since 2020. The present study was designed to collect clinical data on the SAPIEN 3 aortic valve in Chinese patients with bicuspid aortic valve and tricuspid aortic valve stenosis. We analyzed the patient characteristics, procedural features and procedural outcomes of the first 438 patients (223 for bicuspid aortic valve and 215 tricuspid aortic valve) from 21 provinces in 74 sites treated with the SAPIEN 3 valve system for transcatheter aortic valve replacement between September 2020 and May 2022. Procedural mortality was 0.7%. 5 cases during the operation were converted to surgery. Among 438 cases, permanent pacemaker implantation was performed in a total of 12 cases (2.7%). The patient had severe leaflet calcification of the aortic valve, with moderate and severe calcification reaching 39.7% and 35.2% respectively. The size of the implanted valves was predominantly 26 mm and 23 mm, reaching 42.5% and 39.5% respectively. The incidence of moderate or severe perivalvular leak in the postoperative period was 0.5%, with a predominance of 90/10 and 80/20 valve deployment height. There was a significant difference in the deployment height of the valve between bicuspid aortic valve and tricuspid aortic valve, with the bicuspid aortic valve having a more deployment height of 90/10. Annulus size in bicuspid aortic valve group was significantly larger than tricuspid aortic valve group. Valve sizing for oversized, within size, and undersized were different between bicuspid aortic valve and tricuspid aortic valve. Procedural success rates were high, with similar and good results for bicuspid aortic valve and tricuspid aortic valve, low perivalvular leak for both valve types, and low permanent pacemaker implantation rates for both valve types. Annulus size, valve sizing and coronary artery height were significantly different in the BAV and TAV group.

Aortic area/height ratio, peak wall stresses, and outcomes in veterans with tricuspid versus bicuspid aortic valve–associated ascending thoracic aortic aneurysms

BackgroundIn ascending thoracic aortic aneurysm risk stratification, aortic area/height ratio is a reasonable alternative to maximum diameter. Biomechanically, aortic dissection may be initiated by wall stress exceeding wall strength. Our objective was to evaluate the association between aortic area/height and peak aneurysm wall stresses in relation to valve morphology and 3-year all-cause mortality. MethodsFinite element analysis was performed on 270 ascending thoracic aortic aneurysms (46 associated with bicuspid and 224 with tricuspid aortic valves) in veterans. Three-dimensional aneurysm geometries were reconstructed from computed tomography and models developed accounting for prestress geometries. Fiber-embedded hyperelastic material model was applied to obtain aneurysm wall stresses during systole. Correlations of aortic area/height ratio and peak wall stresses were compared across valve types. Area/height ratio was evaluated across peak wall stress thresholds obtained from proportional hazards models of 3-year all-cause mortality, with aortic repair treated as a competing risk. ResultsAortic area/height 10 cm2/m or greater coincided with 23/34 (68%) 5.0 to 5.4 cm and 20/24 (83%) 5.5 cm or greater aneurysms. Area/height correlated weakly with peak aneurysm stresses: for tricuspid valves, r = 0.22 circumferentially and r = 0.24 longitudinally; and for bicuspid valves, r = 0.42 circumferentially and r = 0.14 longitudinally. Age and peak longitudinal stress, but not area/height, were independent predictors of all-cause mortality (age: hazard ratio, 2.20 per 9-year increase, P = .013; peak longitudinal stress: hazard ratio, 1.78 per 73-kPa increase, P = .035). ConclusionsArea/height was more predictive of high circumferential stresses in bicuspid than tricuspid valve aneurysms, but similarly less predictive of high longitudinal stresses in both valve types. Peak longitudinal stress, not area/height, independently predicted all-cause mortality. Video Abstract [Display omitted]

NiFe/FeMn exchange biased systems for bias-field-free magnetization dynamics

The exchange bias phenomenon across a ferromagnet/antiferromagnet interface is of great interest in any spin valve type spintronics device. Here, we show a significant exchange bias effect in Ni80Fe20/Fe50Mn50 systems in the absence of any external field during the thin film growth. The effect of Ni80Fe20 thickness and the application of angular field on hysteresis loops are investigated. Magnetization dynamics using the ferromagnetic resonance technique have been investigated for the understanding of the interfacial properties. Both the hysteresis and the magnetization dynamics data reveal the presence of uniaxial anisotropy, which decreases with increasing the thickness of the Ni80Fe20 layer. Further investigation of the magnetic damping properties indicates the role of the seed layer in addition to the exchange bias effect. The results have potential implications for the development of self-biased systems that support magnetic oscillations and spin-wave-based information propagation without any external bias magnetic field.

Evaluation of Overshunting between Low and Medium Pressure Ventriculoperitoneal Shunts in Dogs with Severe Hydrocephalus Using Frameless Stereotactic Ventricular Shunt Placement

Hydrocephalus is a neurological disorder characterized by an abnormal accumulation of cerebrospinal fluid (CSF) within the ventricular system of the brain, leading to cerebral ventricular dilation, brain parenchyma compression, and neuronal cell loss. Surgery is an effective method of draining excessive amounts of CSF. Ventriculoperitoneal shunt (VPS) allows excess CSF to divert into the abdomen; this device is the most commonly used in the treatment of hydrocephalus both in veterinary and human patients. This study aims to describe the application of two types of VPS, low-pressure valve and medium-pressure valve, using a frameless stereotactic neuronavigational system in eight severe hydrocephalus in dogs and, in particular, analyze the prevalence of postoperative overshunting. Non-communicating hydrocephalus was found in seven dogs, whereas the rest of them had communicating hydrocephalus caused by traumatic brain injury with a skull fracture. The criteria for pressure valve selection depended on the intraoperative intraventricular pressure (IVP) that was determined by the adaptive manometer, according to the human protocol. Low-pressure valve placement was performed in five dogs, and the others received medium-pressure valve placement. The follow-up period was 2 weeks, 4–12 weeks, and 12 weeks to 12 months. Pre- and postoperative information including neurological signs, CT-Scan or MRI, medical treatment, complications, and ventricular volume were compared in all dogs. Seven dogs showed neurological improvement within 2 weeks after surgery. Overshunting was seen in four dogs who received low-pressure valve placement. Three of them had shunt infections within 4 to 6 weeks after surgery. One dog underwent shunt revision from a low-pressure valve to a medium-pressure valve caused by severe overshunting and progressive neurological signs. In addition, cognitive and learning improvements were evaluated based on the owners’ feedback, and neurological signs were examined during the follow-up period in two dogs that received low-pressure valve placement. We conclude that a medium-pressure valve is recommended for overshunting prevention. However, low-pressure valve placement seems to improve cognitive function and learning ability, which is related to an increase in the brain parenchyma observed during long-term monitoring. Moreover, we also report our experience and surgical procedure for frameless stereotactic ventricular shunt placement (FSVSP) in VPS surgery in dogs affected by hydrocephalus.

Endoscopic Aortic Valve Replacement: Initial Outcomes of Isolated and Concomitant Surgery

BackgroundThe applicability of totally endoscopic surgical aortic valve replacement (AVR) in multivalve operations is unknown. This study describes an approach and perioperative outcomes of totally endoscopic isolated and concomitant AVR using various valve types. MethodsA total of 216 patients (114 male; mean age, 71.3 ± 11.3 years) underwent totally endoscopic AVR from May 2017 to October 2022 in a tertiary care center. The 3-port technique was used: a 3- to 4-cm main port without rib spreading, a 10-mm 3-dimensional endoscopic port, and a 5-mm left-hand port with femoral cannulations. Sutures were hand tied with a knot pusher. Descriptive analyses compared perioperative outcomes between patients with or without concomitant procedures. ResultsOf 216 patients, concomitant surgery was performed in 33 (15.2%) patients. Of the 33, 21 (63.6%) had a concomitant mitral procedure. A stented bioprosthesis was implanted in 165 (76.3%) patients, a mechanical valve in 22 (10.2%) patients, and a rapid deployment or sutureless valve in 29 (13.4%) patients. Median operation time and aortic cross-clamp time were 175 minutes (interquartile range; 150-194 minutes) and 78 minutes (interquartile range; 67-92 minutes) for isolated AVR, respectively. Thirty-day mortality occurred in 1 patient (0.5%). Two patients (0.9%) had conversion to sternotomy. Major neurologic events occurred in 3 patients (1.4%). The major adverse event rate was similar between patients with or without concomitant procedures. ConclusionsEndoscopic AVR can safely address concomitant valve diseases.