Superior Hemodynamics Research Articles

Can mechanical heart valves perform similarly to tissue valves? An in vitro study

Current surgical aortic valve (AV) replacement options include bioprosthetic and mechanical heart valves (MHVs), each with inherent limitations. Bioprosthetic valves offer superior hemodynamics but suffer from durability issues, typically initiating deterioration within 7–8 years. MHVs, while durable, necessitate lifelong anticoagulation therapy, presenting risks such as severe bleeding and thromboembolic events. The need for anticoagulants is caused by non-physiological flow through the hinge area during the closed phase and large spikes of regional backflow velocity (RBV) during the closing phase that produces high shear events. This study introduces the iValve, a novel MHV designed to combine the hemodynamic benefits of bioprosthetic valves with the durability of MHVs without requiring anticoagulation. The iValve features eye-like leaflets, a saddle-shaped housing, and an optimized hinge design to enhance blood flow and minimize thrombotic risk. Fabricated using 6061-T6 aluminum and polyether ether ketone (PEEK), twelve iValve iterations were evaluated for their opening and closing dynamics. The reported top-performing prototypes demonstrated competitive performance against industry standards. The proposed iValve prototype exhibited a mean RBV of −4.34 m/s with no spikes in RBV, performing similarly to bioprosthetic valves and significantly outperforming existing MHVs. The iValve’s optimized design showed a 7–10% reduction in closing time and a substantial decrease in RBV spikes, potentially reducing the need for anticoagulation therapy. This study highlights the iValve’s potential to revolutionize prosthetic heart valve technology by offering a durable, hemodynamically superior solution that mitigates the drawbacks of current MHVs.

CT perfusion-guided administration of IV milrinone is associated with a reduction in delayed cerebral infarction after subarachnoid hemorrhage

Delayed cerebral ischemia (DCI) after aneurysmal subarachnoid haemorrhage (aSAH) is a singular pathological entity necessitating early diagnostic approaches and both prophylactic and curative interventions. This retrospective before-after study investigates the effects of a management strategy integrating perfusion computed tomography (CTP), vigilant clinical monitoring and standardized systemic administration of milrinone on the occurrence of delayed cerebral infarction (DCIn). The "before"\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{"before"}}$$\\end{document} period included 277 patients, and the "after"\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{"after"}}$$\\end{document} one 453. There was a higher prevalence of Modified Fisher score III/IV and more frequent diagnosis of vasospasm in the "after"\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{"after"}}$$\\end{document} period. Conversely, the occurrence of DCIn was reduced with the "after"\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{"after"}}$$\\end{document} management strategy (adjusted OR 0.48, 95% CI [0.26; 0.84]). Notably, delayed ischemic neurologic deficits were less prevalent at the time of vasospasm diagnosis (24 vs 11%, p=0.001\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$p=0.001$$\\end{document}), suggesting that CTP facilitated early detection. In patients diagnosed with vasospasm, intravenous milrinone was more frequently administered (80 vs 54%, p<0.001\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$p<0.001$$\\end{document}) and associated with superior hemodynamics. The present study from a large cohort of aSAH patients suggests, for one part, the interest of CTP in early diagnosis of vasospasm and DCI, and for the other the efficacy of CT perfusion-guided systemic administration of milrinone in both preventing and treating DCIn.

Trileaflet Mechanical Valves: What Is Already Known? A Systematic Review

Background: Trileaflet mechanical valves were introduced in the late 90’s. Despite promising results, none have made it past preclinical testing. Ample in vitro, in vivo and computational testing have already been done. Methods: This systematic review is intended to summarize all available preclinical and clinical testing regarding trileaflet mechanical valves. A literature search of Pubmed, Embase and Web of Science (Core Collection) (from inception to August 2023) was performed using a search string that was well defined and not modified during the study. An extensive overview of the search terms used in each database can be found in the appendix. 24 publications were included in this review. Results: This systematic review serves as an overview evaluating the rationale behind a trileaflet mechanical valve as well as the computational, in vitro and in vivo testing. We aim to summarize all available knowledge on trileaflet mechanical valves. Conclusions: A trileaflet mechanical valve is a promising concept, with equal or even superior hemodynamics compared to conventional bileaflet valves based on computational, in vivo and in vitro data. First in men trials are warranted to elude the true potential of this design.

Assessment of Microvascular Hemodynamic Adaptations in Finger Flexors of Climbers.

Climbing performance is greatly dependent on the endurance of the finger flexors which, in turn, depends on the ability to deliver and use oxygen within the muscle. Near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS) have provided new possibilities to explore these phenomena in the microvascular environment. The aim of the present study was to explore climbing-related microvascular adaptations through the comparison of the oxygen concentration and hemodynamics of the forearm between climbers and non-climber active individuals during a vascular occlusion test (VOT). Seventeen climbers and fifteen non-climbers joined the study. Through NIRS and DCS, the oxyhemoglobin (O2Hb) and deoxyhemoglobin (HHb) concentrations, tissue saturation index (TSI), and blood flow index (BFI) were obtained from the flexor digitorum profundus during the VOT. During the reactive hyperemia, climbers presented greater blood flow slopes (p = 0.043, d = 0.573), as well as greater O2Hb maximum values (p = 0.001, d = 1.263) and HHb minimum values (p = 0.009, d = 0.998), than non-climbers. The superior hemodynamics presented by climbers could indicate potential training-induced structural and functional adaptations that could enhance oxygen transportation to the muscle, and thus enhance muscle endurance and climbing performance.

Perceval sutureless bioprosthesis versus Perimount sutured bioprosthesis for aortic valve replacement in patients with aortic stenosis: a retrospective, propensity-matched study

BackgroundRapid-deployment aortic valve replacement (RDAVR) is an alternative to conventional AVR (cAVR) for aortic stenosis. Benefits include a reduction in operative times, facilitation of minimal access surgery and superior haemodynamics compared to conventional valves. However, further evidence is required to inform guidelines, preferably in the form of propensity-matched studies that include mid-term follow-up data.MethodsThis was a single-centre, retrospective, propensity-matched cohort study comparing the Perceval and conventional Perimount Magna Ease valve for short- and mid-term clinical parameters and size-matched mid-term echocardiographic parameters (n = 102 in both groups) from 2014 to 2020. Data were extracted from a nationally managed dataset.ResultsThere were no demographic differences between the matched groups. The Perceval group had shorter cross-clamp time (Perceval 62 [49–81] minutes; Perimount 79 [63–102] minutes, P < 0.001), shorter bypass time (Perceval 89 [74–114] minutes; Perimount 104 [84–137] minutes, P < 0.001), and more frequent minimally-invasive approaches (Perceval 28%; Perimount 5%, P < 0.001). Size-matched haemodynamics showed initially higher gradients in the Perceval group, but haemodynamics equalised at 12 + months. The Perceval group had a more favourable % change in the left ventricular posterior wall dimension at 2 + years (Perceval − 4.8 ± 18; Perimount 17 ± 2).ConclusionsThe Perceval facilitated shorter operations, which may benefit intermediate-high-risk, elderly patients with comorbidities requiring concomitant procedures. It also facilitated minimally invasive surgery. Size-matched haemodynamic performance was similar at mid-term follow-up, with the Perceval possibly better facilitating regression of left ventricular hypertrophy.

Temporary Portocaval Shunt Provides Superior Intraoperative Hemodynamics and Reduces Blood Loss and Duration of Surgery in Live Donor Liver Transplantation: A Randomized Control Trial.

To compare intraoperative hemodynamic parameters, blood loss, renal function, and duration of surgery with and without temporary portocaval shunt (TPCS) in live donor liver transplantation (LT) recipients. Secondary objectives were postoperative early graft dysfunction, morbidity, mortality, total intensive care unit, and hospital stay. Blood loss during recipient hepatectomy for LT remains a major concern. Routine use of TPCS during LT is not yet elucidated. This study is a single-center, open-label, randomized control trial. The sample size was calculated based on intraoperative blood loss. After exclusion, a total of 60 patients, 30 in each arm (TPCS vs no TPCS) were recruited in the trial. The baseline recipient and donor characteristics were comparable between the groups. The median intraoperative blood loss ( P = 0.004) and blood product transfusions ( P < 0.05) were significantly less in the TPCS group. The TPCS group had significantly improved intraoperative hemodynamics in the anhepatic phase as compared with the no TPCS group ( P < 0.0001), requiring significantly less vasopressor support. This led to significantly better renal function as evidenced by higher intraoperative urine output in the TPCS group ( P = 0.002). Because of technical simplicity, the TPCS group had significantly fewer inferior vena cava injuries (3.3 vs 26.7%, P = 0.026) and substantially shorter hepatectomy time and total duration of surgery (529.4 ± 35.54 vs 606.83 ± 48.13 min, P < 0.0001). The time taken for normalization of lactate in the immediate postoperative period was significantly shorter in the TPCS group (median, 6 vs 13 h; P = 0.04). Although postoperative endotoxemia, major morbidity, 90-day mortality, total intensive care unit, and hospital stay were comparable between both groups, tolerance to enteral feed was earlier in the TPCS group. In live donor LT, TPCS is a simple and effective technique that provides superior intraoperative hemodynamics and reduces blood loss and duration of surgery.

Vascular effects and benefits through Helical stent implantation vs. conventional stenting: Methodology and initial Results of The MIMICS FLOW investigator-initiated randomized controlled trial

Abstract Aims Endovascular treatment is the primary revascularization strategy for symptomatic peripheral artery disease (PAD), which not only restores tissue perfusion but also affects local lower limb arterial endothelial function. Endothelial dysfunction is the pathophysiologic principle involved in the progression of atherosclerosis and is a prognostically relevant cardiovascular biomarker. A helical stent with a unique 3D helical geometry promotes laminar swirling blood flow elevating wall sheer stress, providing superior hemodynamic advantages and excellent clinical performance as compared to conventional stenting. The potential impact on endothelial homeostasis and the detailed mechanisms following a biomimetic or conventional stent are unknown. To this aim we now determined the effect of the Biomimics or a conventional stent on endothelial and vascular function in symptomatic PAD. Methods The MIMICS-FLOW is an investigator-initiated single-blind, randomized controlled trial (NCT05447052). The influence of novel stent-platforms with improved hemodynamic capabilities with respect to vasomotion of the vessel wall, vascular function and vascular compliance was measured by flow-mediated dilation (FMD) and arterial stiffness indices. Vascular function was determined in 70 PAD patients, Rutherford 2, 3 and 4 randomized to a helical stent and the conventional straight nitinol stent before and after lower limb intervention with a one-month follow-up in the nonstenotic segment of the proximal SFA. Perfusion indices, TLR rate and primary patency were assessed. Results The methodology and initial results regarding endothelial function after 1 month will be presented at ESC. In brief, 70 Patients aged 67 years were 1:1 randomized to each group prior to stent implantation in the SFA. Rutherford and PACSS class and target lesion locations were balanced between groups. One patient in the helical and 2 patients in the Straight group required a reintervention. A higher improvement in SFA FMD was observed in the helical group as compared to conventional stenting (p&amp;lt;0.05). Importantly, this effect was mirrored also by a greater increase in brachial FMD in the helical vs. conventional group (p&amp;lt;0.05). No impact was observed between groups regarding arterial or aortic stiffness. Conclusions Our RCT data provide evidence for an improved vascular function through swirling flow with superior hemodynamics following a helical stent implantation. These findings support the concept for a better mechanistic understanding to enhance endovascular treatment strategies in PAD.

Pressure-regulated deployment for balloon-expandable TAVI is safe, effective and results in superior valve haemodynamics regardless of prosthesis size

Abstract Background A novel pressure-regulated deployment method for balloon-expandable transcatheter heart valves (THVs) has been developed(1) to improve clinical outcomes by regulating maximal annular wall tension during prosthesis expansion – to both optimise prosthesis-annulus apposition and diminish annular injury. The previous feasibility study(1) showed that THV deployment at wall tensions between 3-3.5 MPa may be associated with reduced paravalvular-leak (PVL) severity and avoidance of annular rupture. Objective To prospectively evaluate the safety and efficacy of the pressure-regulated THV deployment strategy. Methods 341 consecutive patients with severe native aortic stenosis and moderate-severe surgical risk who underwent TAVI with Sapien 3 THVs using a pressure-regulated deployment strategy were included. Target (maximal) deployment pressure was adjusted according to valve size: 5 atm for 29mm, 5.5 atm for 26mm and 6.25 atm for 23mm THVs. Key procedural and clinical outcomes were recorded and analysed using uni- and multi-variate analyses. Results The average patient age was 82.1±6.9 years and 28.2% were female (see attached table). 29.3% had moderate-severe subannular calcification and 14.5% had estimated ≥20% THV oversizing based on TAVI CT. 112 patients (32.8%) were considered at high-risk of annular rupture(2). Post-dilatation rate was 8.2% and was independently associated only with the degree of THV oversizing (OR 3.5, p=0.007, for ≤5% oversizing). On TTE prior to discharge, 85.6% had none/trivial PVL and 14.4% had mild PVL with no observed moderate/severe PVL. Mild PVL was independently associated with age (OR 1.07, p=0.02, per year) and degree of THV oversizing (OR 2.4, p=0.02, for ≤5% oversizing). Resulting THV mean gradient on TTE was 9.7±3.5mmHg overall, with similar results between 23mm (10.5±3.2mmHg) and 26/29mm valves (9.6±3.5mmHg, p=0.2). New PPM rate was 9.6% and was independently associated only with pre-existing RBBB (OR 13.5, p&amp;lt;0.001). New LBBB rate was 11.2% was independently associated only with low THV implantation depth (OR 4.3, p=0.009, for ≤60% of THV length above native aortic annulus). There were no cases of aortic/annular rupture. Conclusions The pressure-regulated strategy for balloon-expandable THV deployment is associated with an excellent safety and efficacy outcomes profile. Notably, there was no significant difference in valve haemodynamics and degree of PVL post-implantation between the smaller (23mm) and larger (26/29mm) THV sizes. These findings suggest that standardisation of THV deployment pressure to achieve target wall tension results in improved haemodynamics, particularly in small-sized valves.Main Table (Truncated)PVL and MG according to THV size

Hemodynamics and diastolic function after native aortic valve preserving vs replacing surgery.

Background Alterations in left ventricular (LV) diastolic function following native tissue-preserving aortic valve (AV) procedures have not been systematically investigated. Furthermore, no comparisons have been made between these changes and those observed after prosthetic AV replacement. Methods From October 2017 to August 2020, 74 patients aged <65 years were referred to our institution for elective AV surgery. Preoperative and postoperative (i.e., discharge, 3-months and 1-year follow-up) transthoracic echocardiography was analyzed. Results Native tissue-preserving surgery was performed in 55 patients (AV repair: n=42, Ross procedure: n=13). The remaining 19 patients underwent prosthetic AV replacement. Preoperatively and at discharge, transvalvular hemodynamics and LV diastolic function were comparable in both groups. At 1-year follow-up, native valve patients showed significantly lower mean transvalvular gradients (7±5 vs. 9±3 mmHg,p=0.046) and peak velocity (1.74±0.51 vs. 2.26±0.096 m/s,p=0.004) and significantly better septal e' (9.1±2.7 vs. 7.7±2.5 cm/s,p=0.043) and lateral e' (14.7±3.1 vs. 11.7±3.7 cm/s,p=0.001). From preoperatively to 1 year postoperatively, septal and lateral e' and E/e' improved markedly after native valve preservation (septal e': +0.7 cm/s,p=0.075; lateral e': +2.3 cm/s,p<0.001; E/e': -1.5,p=0.001) but not after AV replacement (septal e': +0.2 cm/s,p=0.809; lateral e': +0.8 cm/s,p=0.574; E/e': -1.2,p=0.347). Significant negative linear correlations between postoperative transvalvular gradients and absolute changes in lateral e' and E/e' were detected during follow-up. Conclusion Preservation of native tissue in AV surgery results in superior transvalvular hemodynamics compared to prosthetic AV replacement. This may induce faster LV reverse remodeling and may explain more pronounced improvement in LV diastolic function.

Valve-in-valve procedures for degenerated surgical and transcatheter aortic valve bioprostheses using a latest-generation self-expanding intra-annular transcatheter heart valve.

Valve-in-valve (ViV) transfemoral transcatheter aortic valve implantation (TAVI) for failing aortic surgical bioprostheses or transcatheter heart valves (THV) has demonstrated a reasonable clinical and hemodynamic efficacy. Traditionally, self-expanding (SE) supra-annular THV are considered to result in superior hemodynamics compared with balloon-expandable intra-annular THV after ViV. However, so far no data are found on latest-generation intra-annular SE THV for aortic ViV procedures which might be superior with regard to coronary access or subsequent valve reintervention. We herein aim to evaluate a latest-generation SE intra-annular THV for aortic ViV procedures. Between May 2022 and November 2022, five consecutive patients (4/5 female with mean age of 76.2 years and mean Society of Thoracic Surgeons predicted risk of mortality score of 2.9%) received ViV TAVI using the Navitor system (Abbott, Chicago, IL, USA) for treatment of failing surgical bioprostheses or THV. Data were retrospectively analyzed according to updated Valve Academic Research Consortium 3 (VARC-3) definitions. At 30 days, absence of mortality and VARC-3 adjudicated clinical endpoints were documented. Echocardiography at 30 days revealed complete absence of paravalvular leakage and single-digit mean transvalvular gradients (mean of 6.0 mmHg) in all patients. The investigated intra-annular SE THV results in excellent 30-day outcomes for aortic ViV procedures for failing surgical bioprostheses or THV. Despite the intra-annular design, hemodynamic results were excellent, even in small bioprostheses. Ease of use of this valve platform is reflected by only two cycles of resheathing in five ViV procedures with hemodynamic stability during all steps of valve deployment.

CARD3: Wall Shear Stress Signature of the Axial B-impeller Design with Superior Hemodynamics

Purpose: Ventricular assist devices (VADs) present great promise as both bridge-to-transplant and destination therapies for patients with end-stage heart failure. However, complications—such as hemolysis, gastrointestinal bleeding, and degradation of the von Willebrand factor—stand in the way of their widespread application. High levels of wall shear stress resulting from poor hemodynamics within the bladed flow domain are primarily responsible. Computational fluid dynamics (CFD) software was used to map the hemodynamic performance of the B-impeller—a biologically-inspired, helicoid VAD impeller design—and provide detailed insight into the internal flow structures, leading to the shear stress levels within. Methods: The B-impeller with casing was parametrically modeled using a computer aided design software. The geometry was exported to a CFD software and simulations were subsequently run to assess the impeller hemodynamics with respect to the wall shear stress parameter. Results: The B-impeller was found to have a very low shear stress signature versus typical VAD designs, which exhibit much higher signatures than the defined hemolytic threshold of 400 Pascals. The peak and area-averaged values of shear stress were found to be 304.512 Pa (at a flow rate of 9 L/min) and 39.949 Pa (averaged over multiple input flow rate simulations), respectively. Conclusion: The B-impeller concept shows great potential to reduce the adverse hemolytic events associated with most other turbo VADs, in addition to its ability to generate high rates of flow in a minimally intrusive diameter of 8 mm. This biologically inspired, rim-driven impeller design was found to reduce shear stress levels over competitive designs by virtue of its radical, open architecture. This low shear stress signature translates to lowering rates of hemolysis, bleeding, and von Willebrand factor degradation, thereby improving post-implantation outcomes of patients.

BIO3: Advancement of a Novel Polymeric Transcatheter Aortic Valve as an Alternative to Tissue-based Valves

Background: Transcatheter aortic valve replacement (TAVR) is a minimally invasive alternative to surgical valve replacement, originally targeted to elderly patients with aortic stenosis (AS), now increasingly utilized in younger lower risk AS patients. With growth of TAVR the shortcomings of current tissue-based valves are becoming prevalent, namely limited durability and thromboembolic risk. To address these, a polymeric TAV named PolyV-2 (27 mm, PolyNova Cardiovascular Inc, Stony Brook, NY) was designed, optimized, and further tested. Methods: The design of the PolyV-2 (Figure A) was achieved with a battery of in silico simulations including the use of finite element analysis (FEA, Abaqus 2020, Dassault Systems, Providence, RI) to optimize the radial force of the stent frame and minimize leaflet stresses during the cardiac cycle. The PolyV-2 employs a sutureless design via coating the stent with polymer, bypassing problematic hand suturing manufacture of tissue valves. The PolyV-2 utilizes a thermoplastic elastomer polymeric material which was tested in vitro with accelerated wear durability testing according to ISO 5840-3 (2015) with periodic performance testing, evaluated against tissue-based surgical and TAV devices for platelet activation rate (PAR) in a pulsatile flow loop, and evaluated for calcification risk with similar wear testing in a pro-calcific medium. To assess the deposition of calcifications in the valves, both µCT and ICP spectroscopy were used. Results: The optimization process of the PolyV-2 leaflets (Figure B) was able to greatly lower the peak and mean stresses throughout over the cardiac cycle by employing a variable thickness across the entire leaflet. With success of this in silico optimization process, the leaflets were then tested in vitro (Figure C) in accelerated wear testing, performing 1Billion cycles w/o failure – correlating to 25 years of efficacy in vivo, exceeding the 250 million minimum required by the FDA. The material also demonstrated favorable hemocompatiblity as to PAR (Figure D) with activation significantly lower than a commercial tissue TAVR device, more comparable to a surgical device. The pro-calcific wear testing demonstrated no deposition of calcific salts within the polymer leaflet (µCT image, Figure E) compared to the tissue valve and minimal calcium detected with ICP spectroscopy. Conclusion: To mitigate the persistent complications of tissue-based TAV devices, the polymeric PolyV-2 valve was optimized through a battery of in silico and in vitro trials to offer superior hemodynamics, performance, and durability. Proper design and material considerations are essential to ensure successful translation, demonstration of enhanced bio/hemocompatibility and advance of the PolyV-2 through in vivo animal trials.

Conduction system pacing in pediatric and congenital heart disease.

Conduction system pacing (CSP) has evolved rapidly to become the pacing method of choice for many adults with structurally normal hearts. Studies in this population have repeatedly demonstrated superior hemodynamics and outcomes compared to conventional pacing with the recruitment of the native conduction system. Children and patients with congenital heart disease (CHD) are also likely to benefit from CSP but were excluded from original trials. However, very recent studies have begun to demonstrate the feasibility and efficacy of CSP in these patients, with growing evidence that some outcomes may be superior in comparison to conventional pacing techniques. Concerns regarding the technical challenges and long-term lead parameters of His Bundle Pacing (HBP) have been overcome to many extents with the development of Left Bundle Branch Area Pacing (LBBAP), and both techniques are likely to play an important role in pediatric and CHD pacing in the future. This review aims to assimilate the latest developments in CSP and its application in children and CHD patients.

Abstract 08: Computed Tomography Perfusion Of Cerebral Blood Flow During Open Cardiac Massage For Hypovolemic And Normovolemic Cardiac Arrest In Swine

Introduction: Adequate cerebral blood flow (CBF) during open cardiac massage (OCM) in cardiac arrest is critical for survivors to be neurologically intact. Cerebral perfusion is known to be poor during OCM but has not been quantified using a brain perfusion technique. The aim of this study is to measure CBF in swine undergoing OCM in hypovolemia and normovolemia using computed tomography perfusion (CTP) scanning. Methods: Anesthetized swine underwent instrumentation with right atrial and aortic pressure catheters. A pigtail catheter placed in the ascending aorta was used to administer iodinated contrast and CTP imaging acquired. Brain parenchymal attenuation was measured over time from which CBF (mL/100g of brain) and time to peak (TTP; secs) were derived. Animals were then euthanized exsanguination (hypovolemic group) or potassium chloride injection (normovolemic group). Animals were subject to a clamshell thoracotomy, OCM and repeated CTP. Data pertaining to peak coronary perfusion pressure (pCPP; mmHg) was collected and % CPP &gt;15mmHg (% CPP; secs) calculated post hoc. Results: Normovolemic animals achieved superior pCPP compared to the hypovolemic animals (pCPP: 39.3 vs 12.3, p&lt;0.001; % CPP: 14.5 ± 1.9 vs 30.9 ± 6.5, p&lt;0.001). CTP was successfully performed during OCM generating an attenuation curve (figure). The TTP elongated from spontaneous circulation, normovolemia to hypovolemia (5.7 vs 10.8 vs 14.8, p=0.01). CBF during OCM was similar between hypovolemic and normovolemic groups (7.5 ± 8.1 vs 4.9 ± 6.0, p =0.73) which was lower than baseline values (51.9 ± 12.1, p&lt;0.001). Conclusions: OCM in normovolemia generates superior coronary hemodynamics compared to hypovolemia. Despite this, neither generates adequate CBF as measured by CTP, compared to baseline. To improve the rate of neurologically intact survivors, novel resuscitative techniques need to be investigated that specifically target cerebral perfusion as existing techniques are inadequate.

Review of bioprosthetic structural valve deterioration: Patient or valve?

With guidelines progressively recommending bioprosthetic aortic valves in younger patients, a greater emphasis is placed on structural valve deterioration (SVD) as an important clinical endpoint for both transcatheter and surgically implanted valves. However, SVD of bioprosthetic valves is a complex entity with varying definitions in the literature and a multifaceted pathogenesis. This review first aims to establish the most updated definitions of SVD as per the literature. We then explore the patient- and valve-related factors that play the greatest roles in facilitating early SVD. A PubMed literature review was conducted to identify the relevant research in this field within the past two decades. Increasing rates of obesity and metabolic syndrome pose a significant risk to the longevity of bioprosthetic valves. Additionally, externally mounted valves have proven to sacrifice durability for superior haemodynamics. Bioprosthetic SVD continues to be a multifactorial issue that will require various patient- and valve-related factors to be addressed.

Hemodynamics of transcatheter tricuspid valve replacement with Lux-Valve.

ObjectiveTranscatheter tricuspid valve intervention (TTVI) has emerged as an alternative treatment option for high-risk and inoperable patients with symptomatic tricuspid regurgitation (TR). However, scarce data in hemodynamic profiles were available on TTVI. In this paper, we attempt to report the hemodynamic profiles of LuX-Valve.Methods30 patients from July 2020 to July 2021 were enrolled in this study. The patient was diagnosed with severe symptomatic TR. The clinical, invasive hemodynamic, and echocardiographic data were collected.ResultsThe surgical success rate was 100%. The cardiac index and stroke volume increased sharply from 2.42(2.27, 2.85) and 47.8(43.6, 62.0) to 3.04 ± 0.63 and 57.2 ± 14.7, respectively. With the elimination of TR and the increase of forward blood flow of the tricuspid valve, the extravascular lung water [798.0 (673.0, 1147.0) vs. 850.3 ± 376.1, P < 0.01] increased subsequently. The peak right atrium pressure decreased after Lux-Valve implantation (21.0 ± 6.4 vs. 19.4 ± 6.5, P < 0.05). On the contrary, the nadir right atrium pressure increased [10.0(8.0, 15.0) vs. 12.0(10.0, 17.0), P < 0.01]. Notably, the right atrium pressure difference dropped sharply from 9.0(5.0, 13.0) to 5.0(4.0, 8.0) after Lux-Valve implantation. There was no significant change in the pulmonary artery pressure. The right atrium volume decreased from 128(83, 188) to 91(67, 167) mL at 1 month and 107(66,157) mL at 6 months. With the remolding of the right heart chamber, the tricuspid annulus diameter shrank significantly from 42.5 ± 5.6 to 36.6 ± 6.3 mm at 1 month and 36.0 (33.0, 38.0) at 6 months.ConclusionInvasive right atrium pressure may act as a potential candidate for TR evaluation and procedural guidance. Elimination of TR by LuX-Valve implantation improves the cardiac output and right atrium pressure and has no significant effect on the pulmonary artery pressure even with the increment of forward blood flow, suggesting the hemodynamic superiority of transcatheter tricuspid valve replacement but needs further study.

Characterization of cerebral blood flow during open cardiac massage in swine: Effect of volume status.

Introduction: Patients in cardiac arrest treated with resuscitative thoracotomy and open cardiac massage (OCM) have high rates of mortality with poor neurological outcomes. The aim of this study is to quantitate cerebral perfusion during OCM using computed tomography perfusion (CTP) imaging in a swine model of normo- and hypovolemia. Methods: Anesthetized swine underwent instrumentation with right atrial and aortic pressure catheters. A catheter placed in the ascending aorta was used to administer iodinated contrast and CTP imaging acquired. Cerebral blood flow (CBF; ml/100 g of brain) and time to peak (TTP; s) were measured. Animals were then euthanized by exsanguination (hypovolemic group) or potassium chloride injection (normovolemic group) and subjected to a clamshell thoracotomy, aortic cross clamping, OCM, and repeated CTP. Data pertaining to peak coronary perfusion pressure (pCoPP; mmHg) were collected and % CoPP > 15 mmHg (% CoPP; s) calculated post hoc. Results: Normovolemic animals (n = 5) achieved superior pCoPP compared to the hypovolemic animals (n = 5) pCoPP (39.3 vs. 12.3, p < 0.001) and % CoPP (14.5 ± 1.9 vs. 30.9 ± 6.5, p < 0.001). CTP acquisition was successful and TTP elongated from spontaneous circulation, normovolemia to hypovolemia (5.7 vs. 10.8 vs. 14.8, p = 0.01). CBF during OCM was similar between hypovolemic and normovolemic groups (7.5 ± 8.1 vs. 4.9 ± 6.0, p = 0.73) which was significantly lower than baseline values (51.9 ± 12.1, p < 0.001). Conclusion: OCM in normovolemia generates superior coronary hemodynamics compared to hypovolemia. Despite this, neither generates adequate CBF as measured by CTP, compared to baseline. To improve the rate of neurologically intact survivors, novel resuscitative techniques need to be investigated that specifically target cerebral perfusion as existing techniques are inadequate.

476 Cardiac CTA Parameters Can Decrease Pacemaker Rate After Tavr

Introduction: Transcatheter aortic valve replacement (TAVR) has been proven to be a safe and effective alternative to surgical aortic valve replacement (SAVR) in high, intermediate, and low risk patients. Self-expanding transcatheter aortic valves have been shown to have superior hemodynamics when compared to surgery, but continue to have a significantly higher rate of permanent pacemaker (PPM) placement with publications quoting a PPM rate of 17.4%. We sought to assess our institution’s PPM rate compared to recent published data.

Hemodynamics of self-expanding versus balloon-expandable transcatheter heart valves in relation to native aortic annulus anatomy

ObjectivesThis study aimed to compare hemodynamic characteristics of different self-expanding (SE) and balloon-expandable (BE) transcatheter heart valves (THV) in relation to native aortic annulus anatomy.BackgroundA patient centered THV selection becomes increasingly important as indications for transcatheter aortic valve replacement (TAVR) are extended towards lower risk populations.MethodsHemodynamic parameters including mean gradient (MG), effective orifice area (EOA), Doppler velocity index (DVI), degree of paravalvular regurgitation (PVR) and patient-prosthesis mismatch (PPM) were compared by valve type, label size and in relation to quintiles of native aortic annulus area.Results2609 patients were treated at 3 centers in Germany with SAPIEN 3 (n = 1146), ACURATE Neo (n = 649), Evolut R (n = 546) or Evolut Pro (n = 268) THV. SE THVs provided superior hemodynamics in terms of larger EOA, higher DVI and lower MG compared to BE THV, especially in patients with small aortic annuli. Severe PPM was less frequent in SE treated patients. The rate of PVR ≥ moderate was comparable for SE and BE devices in smaller annular dimensions, but remarkably lower for BE TAVR in large aortic annular dimensions (> 547.64 mm2) (2% BE THV vs. > 10% for SE THV; p < 0.001).ConclusionsPatients with small aortic annular dimensions may benefit hemodynamically from SE THV. With increasing annulus size, BE THV may have advantages since PVR ≥ moderate occurs less frequently.Graphical abstract

Sex Disparities in Hemodynamics and Outcomes in Patients Who Underwent Contemporary Transcatheter Aortic Valve Implantation

Studies have reported worse outcomes after transcatheter aortic valve implantation (TAVI) in women receiving early generation transcatheter heart valves (THVs). They have smaller aortic annuli, which could result in higher gradients and more patient-prosthesis mismatch (PPM) after TAVI. We investigated the interactions between contemporary THV hemodynamics and outcomes in women who underwent TAVI. We conducted a retrospective, observational study of patients who underwent contemporary TAVI from 2015 to 2020. We compared baseline characteristics, in-hospital outcomes, and hemodynamics according to sex. We then dichotomized women according to aortic annular area (<430 or ≥430 mm2). Included were 869 patients who underwent TAVI with the SAPIEN 3 or CoreValve Evolut PRO/PRO+. Most patients with small annuli were female (82.5%). They had nonsignificantly higher mortality (30-day: 1.5% vs 0.6%, p=0.313; 1-year: 4.1% vs 2.7%, p=0.265). Those who received self-expanding THVs had lower gradients (8.0 mm Hg vs 13.8 mm Hg, p <0.001), resulting in less moderate PPM (21.2% vs 73.6%, p <0.001), similar severe PPM (19.5% vs 15.3%, p=0.454), and higher rates of pacemaker implantation (14.4% vs 4.2%, p=0.009). Women with small annuli who received a balloon-expandable THV had nonsignificantly higher mortality (30-day: 2.1% vs 0.8%, p=0.631; 1-year: 6.3% vs 1.7%, p=0.118). In conclusion, women who underwent contemporary TAVI had nonsignificantly higher mortality, which could be due to higher PPM rates. These findings were more pronounced in the subset of women with small annuli, in whom those who received self-expanding THVs demonstrated superior hemodynamics at the cost of increased rates of pacemaker implantation.