Conventional Valve Research Articles

Peri-procedural management of transcatheter mitral valve replacement in patients with heart failure.

Over the past decade, transcatheter mitral valve replacement (TMVR) technologies have evolved with the objective of improving outcomes for patients with severe mitral regurgitation (MR) deemed unsuitable for conventional mitral valve surgery. Although the safety and efficacy of transcatheter edge-to-edge mitral valve repair (TEER) is well-established, there is a sense amongst innovators that a major advantage of TMVR may be to offer a more complete solution for the correction of MR in patients whose complex anatomy means that the likelihood of achieving grade 0 or 1 MR with TEER is low. However, abrupt correction of MR in a poorly prepared left ventricle poses a number of unique haemodynamic challenges, particularly when sudden elimination of regurgitant flow causes a relative increase in left ventricular (LV) afterload. Rapid reduction in LV cavity size following MR elimination may itself result in relative LV outflow tract obstruction (LVOTO), irrespective of the intrinsic risk of LVOTO associated with TMVR. Nevertheless, TMVR on a beating heart affords the opportunity to study real-time invasive cardiac indices in high-risk patients with acute reversal of severe MR.

Definition of trAnscatheter heart Valve orIeNtation in biCuspId aortic valve: The DA VINCI pilot study.

To assess the impact of conventional transcatheter heart valve (THV) commissural alignment techniques on THV/coronary overlap and coronary access (CA) after transcatheter aortic valve replacement (TAVR) in bicuspid aortic valve (BAV). Specific Evolut Pro/Pro + and Acurate Neo2 THV orientations are associated with reduced neo-commissural overlap with coronary ostia in tricuspid aortic anatomy. Whether standard orientation techniques are effective also in the setting of BAV anatomy has not been studied. The DA VINCI (Definition of trAnscatheter aortic Valve orIeNtation in biCuspId aortic valve) pilot study is a prospective registry enrolling consecutive patients with severe BAV stenosis undergoing TAVR with last generation supra-annular tall-frame THVs implanted with a cusp overlap view-based commissural alignment. Patients underwent pre- and post-TAVR computed tomography (CT) and coronary angiography. The study endpoint was the rate of favorable THV/coronary overlap, defined as an angle > 40° between the THV commissural post and coronary ostia. Other endpoints were the rates of successful THV alignment with respect to the raphe and of selective CA after TAVR. Moreover, different virtual THV alignment models were tested to identify which one would produce the lower degree of THV/coronary overlap. Thirty-four patients with type 1 BAV with right-left raphe undergoing TAVR (23 with Evolut Pro/Pro + and 11 with Acurate Neo2) were included. At pre-TAVR CT, moderate/severe cusp asymmetry was found in 50% of patients, severe coronary ostia eccentricity was observed in 47.1% for the RCA vs. 8.8% for the LCA (P < 0.007). Correct TVH orientation was achieved in 29 cases. At post-TAVR CT, optimal THV alignment/mild misalignment to the raphe was observed in 86.2%, but a moderate/severe overlap with the coronaries was seen in 13.7% for the RCA and 44.8% for the LCA (P = 0.019). After TAVR, selective RCA cannulation was possible in 82.8% vs. 75.9% for the LCA (P = 0.74), while combined selective CA of both coronaries was possible in less than two-thirds of the patients. Virtual THV alignment in the coronary ostia overlap view assuming a hypothetical circular THV expansion would produce an optimal THV/coronary overlap in almost 90% of cases. Given cusp asymmetry and coronary ostia eccentricity of BAV combined with potential THV asymmetrical expansion, conventional commissural alignment techniques are associated with higher rates of THV misalignment and of moderate/severe neo-commissure overlap with the coronary ostia as compared to tricuspid aortic stenosis, resulting in lower rates of selective CA after TAVR. A modified THV orientation technique based on the coronary ostia overlap view might be preferable in BAV patients.

The Accelerated Transcatheter Heart Valve Testing Environment: Loading, Motion, and Fluid Dynamics.

Transcatheter aortic valve replacements (TAVRs) are an increasingly common treatment for aortic valve disease due to their minimally invasive delivery. As TAVR designs require thinner leaflets to facilitate catheter-based delivery, they experience greater leaflet operational stresses and potentially greater durability issues than conventional surgical valves. Yet, our understanding of TAVR durability remains largely unexplored. Currently, preclinical TAVR durability is evaluated within an ISO:5840 compliant accelerated wear tester (AWT) up to a required 200 × 106 cycles, corresponding to approximately five years in vivo. While AWTs use high cycle frequencies (10-20 Hz) to achieve realistic timeframes, the resulting valve loading behaviors and fluid dynamics are not representative of the in vivo environment and thus may not accurately predict failure mechanisms. Despite the importance of fatigue and failure predictions for replacement heart valves, surprisingly, little quantitative information exists on the dynamic AWT environment. To better understand this environment, we examined frequency and diastolic period effects for the first time using high-speed enface imaging and particle image velocimetry to quantify valve motion and flow, respectively, using a Durapulse™ AWT at frequencies of 10, 15, and 20 Hz. Regardless of operating condition, no waveform achieved a physiologically relevant transvalvular loading pressure, despite having an ISO compliant geometric orifice area (GOA) and waveform. General fluid mechanics were consistent with in vivo but the AWT geometry developed secondary flow structures, which could impact mechanical loading. Therefore, the nonphysiologic loading and variability induced by changes in operating condition must be carefully regulated to ensure physiologically relevant fatigue.

Energy-saving actuation signal for magnetorheological valve train by leveraging hysteresis effect

• Analysis of electromagnetic hysteresis effect in magnetorheological valve train. • Customized pulse actuation signal for leveraging the hysteresis effect in magnetorheological valve train. • Pulse signal optimization for energy saving operation of VVL that improves the engine efficiency. • Customized pulse signal saves actuation energy of magnetorheological valve train. Smart, adaptive, and effective magnetorheological (MR) technology-based devices are replacing conventional brakes, clutches, valves, and dampers. MR valve improves engine performance by enabling variable valve actuation. Constructing an MR valve train is simpler than other active valve systems. However, similar to other electromagnetic valves, the MR valve train consumes considerable electrical energy in controlling the resistance force of the MR fluid such that the valve can remain partially open or fully closed. Thus, an engine equipped with an MR valve expends additional fuel for the actuation of the valve system. In this study, instead of conventional direct current (DC) actuation, an energy-saving customized pulse (CP) signal is proposed for valve actuation by leveraging the electromagnetic hysteresis effect. The applied CP signal causes fluctuations in the generated magnetic flux, resistance force, and consequent valve position. Therefore, the variation in MR resistance force at various duty cycles and negative half cycles was investigated and compared with the required force to perform variable valve lift (VVL). Simulations indicated that a 35% duty cycle with 75% current during the negative half cycle was able to maintain the required force but results in negligible deviation in the resistance force which doesn’t affect the VVL operation. Therefore, the proposed method is advantageous over conventional DC input, conferring actuation energy-savings of approximately 28%.

Midterm results after seamless patch mitral reconstruction.

Some pathologies, including infective endocarditis or sclerotic changes of the mitral leaflet, make the conventional mitral valve repair challenging. Our previously described technique for reconstruction with a seamless pericardial patch makes the repair feasible in some of such difficult pathologies. However, the extent of mitral leaflet segments that could be safely repaired using this technique remains unknown. We investigated the association between the midterm outcome and the extent of mitral leaflet segments replaced by a pericardial patch. From January 2009 to January 2022, patients who underwent mitral valve repair with the seamless 1-patch reconstruction technique were included. The glutaraldehyde-treated pericardium was trimmed and anchored at the papillary muscle. The edge was sewn to the leaflet and the annulus. A total of 49 patients (aged 60±15years) underwent mitral valve repair with this technique. The totally endoscopic approach was used in 27 patients (55%). No patient's repair was converted to valve replacement. No operative mortality or disabling stroke was observed during the early postoperative period. In the midterm follow-up, redo surgery was required in 9 patients (18%). Freedom from mitral valve reintervention rates at 1, 5, and 10years were 84%, 82%, and 82% for all patients, respectively. Freedom from reoperation at 5years was 100%, 92%, and 46% for commissural lesion, 1- to 2-segment involvement, and 3-segment involvement, respectively. There was a significant difference among the 3 groups with regard to mitral valve reoperation rate (P=.002). Mitral valve seamless patch reconstruction provides excellent midterm results if applied to commissural lesions or lesions involving up to 2 segments.

Evolution of Biological Parameters in Patients with Severe Aortic Stenosis Undergoing TAVI - Results at One Month

Abstract Aortic stenosis is one of the most common valve diseases in patients over 60 years of age. Lack of prompt surgical correction by conventional valve replacement or interventional transcatheter aortic valve implantation (TAVI) increases the risk of morbidity and mortality, in the context of worsening clinical picture. Since the first interventional transcatheter valve implantation procedure in 2012 and to date, the evolution of technology and refinement of medical techniques has led to the refinement of the treatment method and thus to the improvement of the prognosis of patients with aortic stenosis undergoing TAVI after only one month.

Behavioral alterations and gills damage in Mytilus galloprovincialis exposed to an environmental concentration of delorazepam

Psychoactive compounds, and benzodiazepines (BZPs) in particular, represent an important class of emerging pollutants due to their large (ab)use and high resistance to degradation. Nowadays it is known that sewage treatment does not completely eliminate these substances and, therefore, BZPs and their metabolites reach concern levels in most aquatic environments all over Europe, ranging from µg/L to ng/L. In this study, we investigated the effects of delorazepam on Mytilus galloprovincialis, a model organism in toxicity testing and a key species in coastal marine ecosystems. Given its psychoactive activity, the study primarily addressed discovering the effects on behavior, by conventional valve opening and closure tests. Possible cytotoxic activity was also investigated by analyzing valve abductor muscles, gills histology, and correlated oxygen consumption. Results demonstrate negative effects on mussel behavior, interference with metabolism, and alteration of gill morphology and protein content. In conclusion, delorazepam confirms its toxicity to aquatic environments, highlighting the possibility that BZDs can ultimately affect the structure of the food web and the functions of the coastal ecosystems.

Experimental investigations and 3D simulations by the overset grid method on twin-screw machines in both pump and turbine mode

Twin-screw pumps due to their particular capabilities, offer u nique b enefits in comparison to other types of pumps. They can also recover wasted energy from the fluid system when run in a reversed way, i.e., in turbine mode. In this study, the possibility of benefiting twin-screw machines instead of conventional control valves in order to recover energy is investigated. Flow physics and energy recovery are analyzed experimentally and by 3D flow simulations in both, pump and turbine mode. Pump and turbine characteristics under different operating points are experimentally measured for low and high viscous fluids, i.e., water and oil, respectively. It is observed that for higher viscosity the dependency of volume flow rate on the pressure difference imposed on the pump is reduced. This observation indicates the significant effect of viscosity on the gap flow. Based on a simulation method by means of overset grid technique, unsteady 3D flow simulations with a high grid quality and a high spatial resolution particularly in gap regions in terms of y + < 1 are conducted and results are validated against experiments. The profound assessment of gap flow based on the simulation results shows that for highly viscous fluids such a soil, the rotational speed of spindles as well as the direction of rotation have a significant effect on gap flow characteristics and consequently on the pump and turbine performance. From the experiments, it is clarified that with a lower rotational speed of spindles and a higher pressure difference, a higher amount of energy up to about 50% of the fluid energy in the piping system can be recovered instead of being dissipated by a conventional control valve.

Design and performance evaluation of a magnetorheological valve with mosquito-coil-plate fluid flow channels

This work proposed and fabricated a magnetorheological (MR) valve with mosquito-coil-plate fluid flow channels. By setting non-magnetic mosquito-coil-plate arc baffles in the radial fluid flow channels of the conventional radial MR valve, MR fluid was forced to flow circumferentially in the mosquito-coil-plate fluid flow channels surrounded by arc baffles. Thus, the effective fluid flow channels of the proposed MR valve were significantly lengthened in the case of fixed volume, and the radial resistance gaps could be easily adjusted by replacing valve cores with different thicknesses. In order to investigate the distributions of the magnetic flux lines and the changes of the magnetic flux density of the MR valve accurately, the 2D and 3D finite element models of the designed MR valve were established by using ANSYS software. Moreover, pressure drop and response time of the MR valve were experimentally evaluated, and the experimental results show that the designed MR valve can not only output larger pressure drop, but also achieve rapid response time. In addition, the proposed MR valve was used as control unit in a valve controlled cylinder system, and its damping performances were tested separately under different applied currents and harmonic excitations with different amplitudes and frequencies. The test results indicate that the proposed MR valve controlled cylinder system can output reliable damping forces in a variety of operating modes. • A new MR valve with mosquito-coil-plate fluid flow channels was designed. • The pressure drop performance was evaluated through theoretical analysis and experimental verification. • A MR valve controlled cylinder system was established, and its damping performance was investigated. • This proposed MR valve has significantly improved its performance by introducing mosquito-coil-plate fluid flow channels.

Design of an additively manufactured hydraulic directional spool valve: an industrial case study

ABSTRACT An industrial case study of an additively manufactured hydraulic spool valve that was designed in close collaboration with our industrial partner Wandfluh AG is presented herein. An existing conventional valve design was redesigned for laser powder bed fusion while considering the current functional and technical requirements. The entire development process is described based on real world requirements, considering the manufacturing and post-processing constraints. The final design was manufactured, tested, and compared with the conventionally manufactured valve. The pressure drop was reduced by 60% through the valve redesign, and a weight reduction of 50% was achieved. This study is concluded by reflecting the development process and identifying potential, learnings, and challenges that can be transferred to other hydraulic components. The importance of generating a large variety of concepts in the divergent design generation phase and performing computational fluid dynamics simulations to assess the potential of these concepts are highlighted.

Early Outcomes of Intuity Rapid Deployment Aortic Valve Replacement Compared With Conventional Biological Valves in Japanese Patients.

This study aimed to elucidate the short-term surgical outcomes and hemodynamics of the Intuity valve compared to the standard bioprosthesis in Japanese patients. Among the 307 consecutive patients who underwent aortic valve replacement (AVR) between February 2019 and March 2021, the Intuity valve was implanted in 95 patients (Intuity group) and a conventional stented bioprosthesis was implanted in 193 patients (conventional group). After propensity score matching, there was no significant difference in in-hospital mortality between the Intuity (n=2, 3%) and conventional groups (n=0, P=0.490). Operation, cardiopulmonary bypass, and aortic cross-clamping times were significantly shorter in the Intuity group. Although the effective orifice area index, trans-prosthetic mean pressure gradient, and peak velocity were similar between the 2 groups at 1 week postoperatively, the Intuity group showed a better mean pressure gradient and peak velocity at 1 year postoperatively. Complete atrioventricular block requiring permanent pacemaker implantation developed in 2 patients (3%) in the Intuity group and none in the conventional group (P=0.476). Mild or greater paravalvular leakage was present in 8 patients (13%) in the Intuity group and 2 patients (3%) in the conventional group (P=0.095). AVR using the Intuity valve in Japanese patients is satisfactory, with a better valve performance and a low incidence of complete atrioventricular block at 1 year postoperatively.

Study on the Erosion of Choke Valves in High-Pressure, High-Temperature Gas Wells

During the process of gas production in high-pressure, high-temperature (HPHT) gas wells, the choke valve, as the most vital component of the surface control equipment, plays a significant role in regulating the output and reducing the fluid pressure to ensure the safety of surface gathering and transportation equipment. High-pressure, high-velocity fluid flow and solid-phase particles cause deterioration of the choke valve. With the enhancement of intelligent and digital oilfields, conventional choke valves have been progressively replaced by electric choke valves. Due to the complex structure of the throttle valve, the flow path and the velocity state of the fluid in the throttle valve, and the distribution law of the erosion fraction are quite distinctive from those in the ordinary throttle valve, meriting further research. In this paper, a simulation of computational fluid dynamics (CFD) was conducted to determine the effects of the pressure distribution, fluid state, divergent particle sizes, and sand volume on the erosion rate of the choke valve. Under various valve openings, the fluid state and the location of high-risk points can be ascertained. The large particle size (diameter greater than 6 mm) of sand and gravel is convenient for causing concentrated erosion in the position of the valve hole, which induces the channel diameter to expand. Fine silt sand (diameter from 0.1 mm to 1 mm) gives rise to relatively uniform abrasion to the choke’s current-facing surface. This study can optimize the layout of the choke valve and reduce the cost and number of switching wells, thereby decreasing the frequency of maintenance and the pressure fluctuation’s effect on the formation.

Outcomes comparison between robotic and conventional mitral valve surgery: a systematic review and meta-analysis

Abstract Background Robotic-assisted cardiac surgery has emerged as a popular minimal invasive cardiac surgery approach, as it provides several advantages compared to conventional and other minimally invasive approaches. Mitral valve surgeries, including repair and replacement, are currently the most common cardiac surgeries performed with a robotic approach. However, there are concerns that surgeon's learning curve and prolonged operation time associated with this approach could compromise the surgical outcomes, hence the low acceptance of the technique in the clinical setting. In addition, despite various studies comparing robotic and conventional mitral surgery, it remains unclear whether the former would give comparable, if not better, outcomes. Purpose This study aims to compare the outcomes of robotic and conventional sternotomy mitral valve surgeries. Methods A comprehensive literature search was performed through Pubmed, CENTRAL, and ScienceDirect for studies comparing robotic and sternotomy approach for mitral valve repair and replacement. Studies were screened with our eligibility criteria, and their quality was examined using the Newcastle-Ottawa scale. The primary outcome analysed in this study was the perioperative mortality. Results Twelve studies involving 4300 patients (2223 experienced robotic surgery) were included. Pooled analysis showed that patients who underwent robotic surgery had a significant decrease in perioperative mortality compared to those who underwent sternotomy surgery (RR 0.33, 95% CI 0.18, 0.60, p=0.0003, I2=0%). Moreover, ICU length of stay was also shorter in the robotic group (MD −13.67, 95% CI −20.04, −7.29, p&amp;lt;0.0001, I2=93%). Re-operation risk due to bleeding was not significantly different between both groups (RR 1.13, 95% CI 0.79, 1.62, p=0.51, I2=0%). Egger's test result showed no evidence of small-study effects (p=0.83), and the funnel plot appeared symmetrical, meaning there was no publication bias. Conclusion Results from our meta-analysis refute the current concerns limiting the acceptance of robotic approach in mitral valve surgeries, showing significantly lower perioperative mortality and ICU length of stay, as well as a comparable re-operation risk due to bleeding with the conventional approach. Funding Acknowledgement Type of funding sources: None.

High Tracking Control for a New Independent Metering Valve System Using Velocity-Load Feedforward and Position Feedback Methods

The new configuration of independent metering valve (NIMV) system uses three proportional valves that gave been effectively proven to be energy saving compared with a conventional independent metering valve system in the fixed load condition. However, the variable load condition completely affects the accuracy and energy consumption during the operation of excavators. To improve the motion tracking precision and reduce the energy consumption of the NIMV system, a novel control method based on the coordinated control of the pump and the valve is proposed. In detail, the valve is controlled by considering velocity, load force, and position feedback of the cylinder. Meanwhile, velocity feedforward and position feedback methods are used to control the speed of the pump. In addition, a switching mode for the NIMV system is designed to flexibly select the metering modes based on the load and velocity conditions. To confirm the effectiveness of the proposed control method, the co-simulation model is built by using the AMESim and MATLAB software. From the results, the proposed method not only has high trajectory tracking precision with the displacement error of the cylinder at around 3.6% but also achieves up to 6.4% energy saving.

Flow-reduced double valve actuation for improving the dynamic performance of electro-hydraulic servo drive

Due to the negative correlation between the frequency response and the rated flow of the servo valve, there remains challenge to achieve high dynamic response of large-flow servo valve-controlled hydraulic systems under extreme operating conditions. Although the effective bandwidth of such system can be extended via various control methods, the inherent performance limit of hardware limits further improvement of the system dynamic response. In this paper, a flow-reduced double valve actuation strategy is proposed to improve the performance of electro-hydraulic servo drives. By reducing the actually used flow, the frequency response of the servo valve is enhanced due to the decreased hydraulic spring force and transient flow force acting on the spool. Two flow-reduced servo valves are adopted in parallel to meet large flow along with the improved dynamic performance. Simulation research is conducted and a servo valve-controlled shaking table with a specially designed valve block is used for experimental validation. Simulation and experimental results prove that the proposed strategy possesses better dynamic performance than the conventional single valve actuation.

Robotic versus conventional sternotomy mitral valve surgery: a systematic review and meta-analysis.

BackgroundRobotic-assisted mitral valve surgery (RMVS) is becoming an increasingly performed procedure in cardiac surgery, however, its true safety and efficacy compared to the gold standard conventional sternotomy approach [conventional sternotomy mitral valve surgery (CSMVS)] remains debated. The aim of this meta-analysis was to provide a comprehensive analysis of all available literature comparing RMVS to CSMVS.MethodsAn electronic search of five databases was performed to identify all relevant studies comparing RMVS to CSMVS. Pre-defined primary outcomes of interest included all-cause mortality, cerebrovascular accidents (CVA) and re-operation for bleeding. Secondary outcomes of interest included cross clamp time, cardiopulmonary bypass (CPB) time, intensive care unit (ICU) and hospital length of stay (LOS), post-operative atrial fibrillation (POAF) and red blood cell (RBC) transfusion.ResultsThe search strategy identified fourteen studies qualifying for inclusion in this meta-analysis comparing RMVS to CSMVS. The outcomes of 6,341 patients (2,804 RMVS and 3,537 CSMVS) were included. RMVS had significantly lower mortality when compared to CSMVS group in both the unmatched [odds ratio (OR) 0.33; 95% confidence interval (CI): 0.19–0.57; P<0.001] and matched cohorts (OR 0.35; 95% CI: 0.15–0.80; P=0.01). There was no significant difference in rates of CVA or re-operation for bleeding between the two groups in either the entire included cohort or matched patients. CSMVS had significantly shorter cross clamp time by 28 minutes (95% CI: 19.30–37.32; P<0.001) and CPB time by 49 minutes (95% CI: 36.16–61.01; P<0.001) which remained significantly shorter in the matched cohorts. RMVS had shorter ICU [mean difference (MD) 26 hours; 95% CI: −34.31 to −18.52; P<0.001] and hospital LOS (MD 2 days; 95% CI: −2.66 to −1.37; P<0.001), which were again both significantly shorter in the matched cohort. RMVS group also had fewer RBC transfusions (OR 0.44; 95% CI: 0.28–0.70; P<0.001).ConclusionsCurrent evidence on comparative outcomes of RMVS and CSMVS is limited with only low-quality studies currently available. This present meta-analysis suggests that RMVS may have lower mortality and shorter ICU and hospital LOS, however CSMVS may be associated with significantly shorter cross clamp and CPB times. Further analysis of high-quality studies with randomized data is required to verify these results.

Edge-to-Edge Technique Used as a Bailout for Suboptimal Mitral Repair: Long-term Results

BackgroundFor cases of initial suboptimal mitral valve repair, the edge-to-edge (EE) technique has been used as a bailout procedure. However the long-term durability of those rescued mitral valves is currently unknown. With this study we aim to evaluate the long-term clinical and echocardiographic results of the EE technique used to rescue patients with initial suboptimal conventional mitral valve repair. MethodsA retrospective review of our institutional database was done to query for patients who had undergone mitral valve repair with the EE technique used as a bailout procedure. The cumulative incidence function using death as a competing event was used to estimate cardiac death and redo for mitral valve replacement. To describe the time course of mitral regurgitation, we performed a longitudinal analysis using generalized estimating equations with random intercept for correlated data. ResultsEighty-one patients were selected. The median follow-up was 9.1 years (interquartile range, 6.7-12.1; maximum, 22.6 years). At 15 years the estimated Kaplan-Meier overall survival was 63.2% ± 8.69% (95% confidence interval, 43.76-77.46) and the predicted rate of moderate to severe mitral regurgitation recurrence was 16.67%. At 15 years the cumulative incidence function for redo for mitral valve replacement with death as a competing event was 2.5% (95% confidence interval, 0.48-7.84). No case of more than mild mitral stenosis was detected. ConclusionsThe EE technique can be effectively used as a bailout procedure in patients with suboptimal conventional mitral valve repair with satisfactory long-term results.

Effect of the helical-spiral shroud intake valve on flow in cylinder of internal combustion engine

In this paper, we proposed a method to increase the mixing performance of gasoline and intake air by attaching a helical-spiral shroud to the intake valve. The effect of the height and revolution number of helical-spiral shroud on the generation of swirl in the engine cylinder are analyzed. The height is 20 and 25 mm, and the revolution number is changed to 1 and 1.5 turns. A three-dimensional simulation model using the shear stress transport k–ω model is used as the turbulence model to predict the air flow characteristics through the intake valve and engine cylinder in the intake and compression strokes. As a result, the helical-spiral shroud intake valve (HSSIV) generally increases the swirl ratio compared to the general valve, and the swirl ratio in the HSSIV with a height of 20 mm and revolution number of one turn has a maximum value of 77 around 90CAD. It also shows that HSSIV has little effect on the volumetric efficiency reduction while increasing the swirl ratio from different geometrical properties than the conventional shroud valves.

Time independent myocardial protection of single dose HTK cardioplegia: Comparison of conventional and minimally invasive mitral valve repair

Minimally invasive mitral valve surgery may require a prolonged period of myocardial ischemia. Cardioplegic solutions that necessitate a single dose for adequate myocardial protection are evoked to simplify surgery and result to be appealing in this setting. The aim of this study was to assess early outcomes after minimally invasive versus conventional mitral valve repair using one single dose of histidine-tryptophan-ketoglutarate solution (HTK; Custodiol) for myocardial protection. A retrospective analysis of prospectively collected data of patients who underwent primary isolated mitral valve repair between 2015–December 2021 was undertaken. Primary end-point was peak creatine kinase (CK)-MB within the first 24 hours after surgery. Secondary endpoints included operation and aortic cross-clamp times, in-hospital mortality, hospital and ICU stay, postoperative bleeding and rethoracotomy, and cumulative blood transfusion. All values are given as mean ± SD, P < 0.05 was considered as statistically significant. Analysis was performed by using the SPSS statistic software. 276 patients were included in the study (64 conventional vs. 272 minimally invasive procedure). Baseline patient characteristics did not differ between the groups except gender distribution (43.7% vs. 22.2% female, P = 0.02). There were no in-hospital death in the whole cohort. Operation and aortic cross-clamp times were significantly lower in the conventional group (208 ± 5 vs. 277 ± 4 min, P = 0.001 76 ± 20 vs 107 ± 26 min, P = 0.001, respectively). Peak CK-MB showed no significant differences between the groups (81 ± 53 vs. 76 ± 55 U/l). Postoperative measures did not differ between the groups. The present data confirms similar outcomes between conventional and minimally invasive mitral valve repair. Despite longer operation and aortic cross-clamp times, single dose cardioplegia with HTK solution provides a time independent excellent myocardial protection during minimally invasive surgery.

Cardiac Surgery 2021 Reviewed

PubMed displayed more than 35,000 hits for the search term "cardiac surgery AND 2021." We used the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) approach and selected relevant publications for a results-oriented summary. As in recent years, we reviewed the fields of coronary and conventional valve surgery and their overlap with their interventional alternatives. COVID reduced cardiac surgical activity around the world. In the coronary field, the FAME 3 trial dominated publications by practically repeating SYNTAX, but with modern stents and fractional flow reserve (FFR)-guided percutaneous coronary interventions (PCIs). PCI was again unable to achieve non-inferiority compared with coronary artery bypass graft surgery (CABG) in patients with triple-vessel disease. Survival advantages of CABG over PCI could be linked to a reduction in myocardial infarctions and current terminology was criticized because the term "myocardial revascularization" is not precise and does not reflect the infarct-preventing collateralization effect of CABG. In structural heart disease, new guidelines were published, providing upgrades of interventional treatments of both aortic and mitral valve disease. While for aortic stenosis, transcatheter aortic valve implantation (TAVI) received a primary recommendation in older and high-risk patients; recommendations for transcatheter mitral edge-to-edge treatment were upgraded for patients considered inappropriate for surgery. For heart team discussions it is important to know that classic aortic valve replacement currently provides strong signals (from registry and randomized evidence) for a survival advantage over TAVI after 5 years. This article summarizes publications perceived as important by us. It can neither be complete nor free of individual interpretation, but provides up-to-date information for decision-making and patient information.