Hemodynamic Comparison Research Articles

Exercise postcapillary pulmonary hypertension in patients with chronic thromboembolism. Role of multimodal resting and exercise assessment

Abstract Introduction Chronic thromboembolic pulmonary disease refers to the presence of thrombotic material after a pulmonary embolism (PE), exercise limitation and the absence of resting pulmonary hypertension (PH) but impaired right ventricular and pulmonary vascular reserve during exercise causing exercise precapillary PH (exprecapPH). However, in some patients, PH arises from an abnormal increase in pulmonary arterial wedge pressure (PAWP) with exercise in relation to underlying diastolic dysfunction, with thrombotic material not playing a substantial role. Whether these patients present distinct non-invasive and resting invasive parameters remains largely unknown. Purpose To compare the different exercise hemodynamic profiles of patients with chronic thromboembolism to identify clinical, echocardiographic, functional and hemodynamic parameters associated with exercise postcapillary PH (expostcapPH). Methods Data come from a prospective cohort of 71 symptomatic patients with perfusion defects in lung scintigraphy and computed tomographic confirmation of chronic thrombi despite anticoagulation ≥3 months after PE without or mild resting PH, undergoing exercise cardiac catheterization via supine cycle ergometry. A multipoint mean pulmonary artery pressure (mPAP)/cardiac output (CO) and mean PAWP/CO slope were calculated. Simultaneous stress echocardiography was available in 43 patients. Cardiopulmonary exercise test (CPET) was performed 24 hours before catheterization. Results Mean age was 53±13.9 years, 46 (64.8%) were males. 37 patients showed normal exercise hemodynamics, while 26 developed exprecapPH and 8 expostcapPH. Mean mPAP/CO slope was 3.1±1.6 mmHg/L/min, mean PAWP/CO slope 1.5±0.9 mmHg/L/min. Patients with expostcapPH were older, had a higher body mass index and hypertension. Comparison of hemodynamics, CPET and resting echocardiography is depicted in the table. Patients with expostcapPH, similar to those without exercise PH, had significantly lower resting pulmonary pressures and pulmonary vascular resistance than those with exprecapPH. These differences remained at peak exercise; however, while resting PAWP did not differ between groups, a significant increase in PAWP was unmasked in patients with expostcapPH compared to the other groups, and accordingly a significant difference in the PAWP/CO slope. Regarding CPET, patients with expostcapPH had higher baseline systolic blood pressure and lower functional capacity (VO2 max, VO2 at VT1, O2 pulse, OUES). Resting TAPSE/PASP was higher in patients with expostcapPH compared to those with exprecapPH. Conclusions Patients with chronic thromboembolism and expostcapPH exhibit distinct clinical features and have lower functional capacity, while resting PAWP did not allow differentiation between groups. Further studies are warranted to delineate characteristic elements of patients with underlying diastolic dysfunction due to its distinct prognosis and treatment.

4D-Flow MRI and Vector Ultrasound in the In-Vitro Evaluation of Surgical Aortic Heart Valves - a Pilot Study.

The aim of this study was the initial investigation of 4D-Flow MRI and Vector Ultrasound as novel imaging techniques in the in-vitro analysis of hemodynamics in anatomical models. Specifically, by looking at the hemodynamic performance of state-of-the-art surgical heart valves in a 3D-printed aortic arch. The mock circulatory loop simulated physiological, pulsatile flow. Two mechanical and three biological aortic valves prostheses were compared in a 3D-printed aortic arch. 4D magnetic resonance imaging and vector flow Doppler ultrasound served as imaging methods. Hemodynamic parameters such as wall shear stress, flow velocities and pressure gradients were analyzed. The flow analysis revealed characteristic flow-patterns in the 3D-printed aortic arch. The blood-flow in the arch presented complex patterns, including the formation of helixes and vortices. Higher proximal peak velocities and lower flow volumes were found for biological valves. The mock circulatory loop in combination with modern radiological imaging provides a sufficient basis for the hemodynamic comparison of aortic valves.

Computational model-based hemodynamic comparisons of traditional and modified idealized models of autologous radiocephalic fistula.

Autologous arteriovenous fistula (AVF) is a commonly used vascular access (VA) for hemodialysis, and hemodynamic changes are one of the main factors for its failure. To explore the effect of geometry on the hemodynamics in the AVF, a modified model is built with a gradual and smooth turn at the anastomosis and is compared with the traditional model, which has an abrupt sharp turn at the anastomisis. Transient computational fluid dynamics (CFD) simulations were performed for the comparison and analysis of the hemodynamic fields of the two models at different stages of the pulse cycle. The results showed that the low shear stress region and high oscillatory shear stress region in the modified AVF model coincided with regions of intimal hyperplasia that have been identified by previous studies. A comparison with the blood flow velocities measured in vivo was performed, and the error between the simulation results and the medical data was reduced by 22% in the modified model, which verifies the rationality and utility of the modified model.

Comparison of intraoperative hemodynamics in classical and single-port adrenalectomy

BACKGROUND: Pheochromocytoma (PCC) is a tumor from the chromaffin tissue of the adrenal medulla, capable of hyperproduction of catecholamines. An important feature of pheochromocytoma, due to its hormonal activity, is the threat of sudden changes in hemodynamic parameters during surgical treatment. Retroperitoneoscopic access is currently becoming increasingly popular in the surgical treatment of chromaffin tumors of the adrenal glands. In clinical practice, two variants of the mentioned access are used: classic (three-port) and single-port. In this study, the influence of these options of retroperitoneoscopic access on intraoperative hemodynamic control was evaluated.AIM: Comparison of treatment results and intraoperative hemodynamic parameters of patients with adrenal pheochromocytomas operated with single-port and three-port retroperitonescopic access options.MATERIALS AND METHODS: A retrospective single-center cohort study was conducted on a sample of patients initially operated for pheochromocytoma at the Pirogov St. Petersburg State University High Medical Technology Clinic from October 2015 to February 2020 with intraoperative invasive hemodynamic control using PiCCO+ systems.RESULTS: 47 patients were examined, 24 of whom underwent single–port adrenalectomy (included in the first group), 23 — three-port (second group). The average tumor size in the second group was larger (40.12±9.3 and 56.7±21.5, p<0.05), presumably, in this regard, the average duration of surgery was statistically significantly higher (73±21.5 and 111.7±36.1, p<0.05). The body mass index (BMI) of patients in the two groups did not differ statistically significantly. Intraoperatively measured values of maximum and minimum mean systolic and diastolic blood pressure, the number of episodes of increased diastolic blood pressure above 120 mmHg and their duration did not differ statistically in both groups (p>0.05). Episodes of increased systolic blood pressure above 180 mm Hg were more frequent in the second group (p=0.03), but their total duration in the two groups was without significant differences (p>0.05). Intraoperative consumption of antihypertensive drugs during the release of the adrenal gland and vasopressor drugs after compression of the central vein of the adrenal gland were similar. Blood pressure after compression of the central vein in the first and second groups did not differ significantly (p>0.05). No deaths and postoperative complications were registered in both groups.CONCLUSION: Single-port modification of retroperitoneoscopic access with sufficient experience of the anesthesiological team and the operating surgeon does not lead to deterioration of hemodynamic control and operation results, being safe and effective in the surgical treatment of pheochromocytoma.

Hemodynamic comparison between minimally invasive and conventional approaches in off-pump coronary artery bypass grafting: A randomized controlled trial

This study aimed to investigate the hypothesis that minimally invasive coronary artery bypass grafting (CABG) induces fewer hemodynamic alterations compared to conventional approaches, attributing this to reduced heart rotation during grafting. Given the critical role of hemodynamic stability in patient outcomes and the growing popularity of minimally invasive CABG, we sought to assess and compare the hemodynamic responses during left anterior descending artery grafting. This randomized controlled trial was conducted at a tertiary center, enrolling a total of 60 patients, with 30 in each group. Parameters such as heart rate (HR), mean arterial pressure (MAP), central venous pressure (CVP), and perfusion index (PI) were measured at baseline, after octopus stabilization prior to grafting, at 3 minutes during grafting, and at the end of grafting. Additionally, serum lactate levels were assessed at baseline and upon completion of grafting. The baseline HR was comparable between the groups. However, the trends in HR revealed a significant increase in the conventional group after octopus stabilization (P value = 0.0038), at 3 minutes post-initiation of grafting (p < 0.001), and at the completion of grafting (P value = 0.001). MAP and CVP remained comparable at all time points. Notably, PI showed a significant increase in the conventional group during positioning (after octopus stabilization), at 3 minutes post-initiation of grafting, and at the completion of grafting. There were no significant differences in lactate levels between the groups. Despite no significant differences in MAP, CVP, and lactate levels, our findings highlight significant disparities in HR and PI between the two groups. We conclude that the observed variations in heart rate may be attributed to minimal positional changes in the minimally invasive approach compared to the conventional approach.

Assessment of Dynamic Cerebral Autoregulation During Long-Term Exposure to High Altitude in Normal Subjects by Ultrasonography.

To evaluate changes in dynamic cerebral autoregulation (CA) during short-term and long-term exposure to high altitude with ultrasonography, and also study the sex differences in the response of CA to altitude. We assessed the differences in dynamic CA and measured with Doppler ultrasound of the bilateral internal carotid artery (ICA), vertebral artery (VA), and middle cerebral artery (MCA) and the values of basic information within 48 hours and at 2 years after arrival at Tibet in 65 healthy Han young Chinese volunteers, meanwhile, we compared the resistance index (RI) and pulsatility index (PI) of the right MCA at inhale oxygen 8 minutes when a newcomer with 2 years after arrival at Tibet. With 2 years of altitude exposure, the SaO2 of all subjects was above 90%, the mean PEF, DAP, and HR values decreased, HGB increased compared within 48 hours in same-gender groups. Comparisons of cerebral hemodynamics between before 2 years and after 2 years within male and female groups, the mean RI and PI values of bilateral MCA after 2 years were significantly higher than before 2 years, at the same time, the mean RI and PI values of bilateral ICA were significant differences (P < .05) between male groups, with regard to female groups, showed that the mean RI and PI values of bilateral VA were significant differences (P < .05). Comparisons of Right MCA hemodynamics between after oxygen uptake 8 minutes and 2 years, the mean RI and PI values were no significant difference within male and female groups (P > .05). Acute mountain sickness could result from an alteration of dynamic autoregulation of cerebral blood flow, but the impaired autoregulation may be corrected with the extension of time, furthermore, the response of CA to altitude in males and females are different.

(1092) - Comparison of Hemodynamics in Patients Bridged to Transplant with Temporary vs Durable LVAD

(1092) - Comparison of Hemodynamics in Patients Bridged to Transplant with Temporary vs Durable LVAD

Hemodynamic Comparison of the On-X and Top Hat Mechanical Aortic Valve Prostheses

BackgroundThere are limited data comparing hemodynamic valve function in mechanical aortic valve prostheses. This study compared the hemodynamic function of 2 commonly used mechanical aortic valve (AV) prostheses, the On-X (Artivion) and Top Hat (CarboMedics Inc) valves. MethodsThis study was a retrospective analysis of 512 patients who underwent AV replacement with the On-X (n = 252; 49%) or Top Hat (n = 260; 51%) mechanical valves between 2011 and 2019. Patients were matched on the basis of selected variables. Echocardiographic data were collected preoperatively and postoperatively over a median follow-up of 1.39 years. ResultsA total of 320 patients were matched, 160 patients in each group. Despite being matched for left ventricular outflow tract diameter, patients in the Top Hat group received a greater prevalence of smaller tissue annulus diameter valves (≤21 mm) (83% vs 38%; P < .001). Patients in the On-X group had longer aortic cross-clamp times (78 minutes vs 64 minutes; P < .001) during isolated aortic valve replacement. Discharge echocardiography showed no difference in the AV area index between both groups (1.00 cm2/m2 vs 1.02 cm2/m2; P = .377). During longer-term echocardiographic follow-up, the AV area index remained stable for both valves within their respective tissue annulus diameter groups (P = .060). ConclusionsThere was no difference between the 2 valves with respect to the AV area index at discharge, and hemodynamic function was stable during longer-term follow-up. The longer aortic cross-clamp time observed in the On-X group may indicate increased complexity of implantation compared with the Top Hat group.

Hemodynamic Comparison of Resilia and Sapien 3/Ultra Transcatheter Heart Valves in Transcatheter Aortic Valve Replacement.

Hemodynamic Comparison of Resilia and Sapien 3/Ultra Transcatheter Heart Valves in Transcatheter Aortic Valve Replacement.

Usage of computational method for hemodynamic analysis of intracranial aneurysm rupture risk in different geometrical aspects

The importance of the parent vessel geometrical feature on the risk of cerebral aneurysm rupture is unavoidable. This study presents inclusive details on the hemodynamics of Internal carotid artery (ICA) aneurysms with different parent vessel mean diameters. Different aspects of blood hemodynamics are compared to find a reasonable connection between parent vessel mean diameter and significant hemodynamic factors of wall shear stress (WSS), oscillatory shear index (OSI), and pressure distribution. To access hemodynamic data, computational fluid dynamics is used to model the blood stream inside the cerebral aneurysms. A hemodynamic comparison of the selected cerebral aneurysm shows that the minimum WSS is reduced by about 71% as the parent vessel’s mean diameter is increased from 3.18 to 4.48 mm.

Comparison of sedation quality and hemodynamics in privately-owned adult dogs undergoing intradermal skin testing with Zenalpha or Dexdomitor

Comparison of sedation quality and hemodynamics in privately-owned adult dogs undergoing intradermal skin testing with Zenalpha or Dexdomitor

Comparison of Hemodynamics in Jet Ventilation vs. Intermittent Apnea for Airway Stenosis Surgery.

The objective of this study is to assess the impact of two different ventilation techniques, jet ventilation and apneic anesthesia with intermittent ventilation (AAIV), on patient hemodynamics and operative time during endoscopic laryngotracheal stenosis surgery. Retrospective chart review of patients who underwent airway dilation for laryngotracheal stenosis by a single surgeon at a single institution from October 1, 2000 through January 2, 2020. Logistic regression, Mann-Whitney U tests and chi square analysis were used to determine statistical significance. A total of 157 patients, 43 (27.4%) male and 114 (72.6%) female, and 605 total encounters were included for analysis. There were no significant differences in hemodynamic outcomes when comparing the AAIV and jet ventilation groups. Specifically, there was no significant difference in either peak end-tidal CO2 or nadir O2 saturation between the AAIV and jet ventilation groups (p = 0.4016) and (p = 0.1357), respectively. The patients in the AAIV group had a significantly higher median BMI 32.93 (27.40-39.40) compared with 28.80 (24.1-32.65) (p = 0.0001). Although not necessarily clinically significant, patients with higher BMI had lower median O2 nadirs (97.8%) than non-obese patients (99.2%) (p < 0.0001). The median total procedure time was equivalent when comparing the two ventilation techniques. AAIV is a safe method of ventilation for patients undergoing endoscopic laryngotracheal stenosis surgery with no significant differences in patient hemodynamics or procedure time when compared with jet ventilation. AAIV was the preferred method of ventilation for obese patients undergoing endoscopic laryngotracheal stenosis surgery. 3 Laryngoscope, 134:1343-1348, 2024.

Comparison of portal vein hemodynamics with ultrasound-based elastography for the prediction of liver fibrosis in patients with chronic liver disease

Chronic liver disease includes nonalcoholic fatty liver disease, progresses from steatosis and hepatitis to fibrosis and cirrhosis, with hemodynamic changes in portal blood flow. This study aimed to compare portal vein hemodynamics with liver stiffness (LS) and steatosis and included 28 subjects with chronic liver disease, in whom LS and steatosis were evaluated in the same image employing two elastography techniques: transient elastography (TE) with controlled attenuation parameter (CAP) using a FibroScan and two-dimensional shear-wave elastography (2D-SWE) with attenuation imaging (ATI). Additionally, peak maximum velocity (Vmax) of the right portal vein and spleen stiffness with 2D-SWE were evaluated. A strong positive correlation was present between LS values obtained with TE and 2D-SWE and between the attenuation coefficients of steatosis obtained with CAP and ATI. Additionally, a negative correlation was present between LS values and the Vmax of the right portal vein (r = 0.415, p = 0.031). The optimal Vmax cutoff value for discriminating liver fibrosis with an LS value of > 5 kPa was < 17 cm/s; the ability of Vmax to predict fibrosis was comparable to that of the FIB4-index. Low Vmax of the right portal vein was useful for identifying liver fibrosis in patients with chronic liver disease.

Hemocompatibility and hemodynamic comparison of two centrifugal LVADs: HVAD and HeartMate3

Mechanical circulatory support using ventricular assist devices is a common technique for treating patients suffering from advanced heart failure. The latest generation of devices is characterized by centrifugal turbopumps which employ magnetic levitation bearings to ensure a gap clearance between moving and static parts. Despite the increasing use of these devices as a destination therapy, several long-term complications still exist regarding their hemocompatibility. The blood damage associated with different pump designs has been investigated profoundly in the literature, while the hemodynamic performance has been hardly considered. This work presents a novel comparison between the two main devices of the latest generation–HVAD and HM3–from both perspectives, hemodynamic performance and blood damage. Computational fluid dynamics simulations are performed to model the considered LVADs, and computational results are compared to experimental measurements of pressure head to validate the model. Enhanced performance and hemocompatibility are detected for HM3 owing to its design incorporating more conventional blades and larger gap clearances.

Comparison of hemodynamics during induction of general anesthesia with remimazolam and target-controlled propofol in middle-aged and elderly patients: a single-center, randomized, controlled trial

BackgroundRemimazolam confers a lower risk of hypotension than propofol. However, no studies have compared the efficacy of remimazolam and propofol administered using target-controlled infusion (TCI). This study aimed to investigate hemodynamic effects of remimazolam and target-controlled propofol in middle-aged and elderly patients during the induction of anesthesia.MethodsForty adults aged 45–80 years with the American Society of Anesthesiologists Physical Status 1–2 were randomly assigned to remimazolam or propofol group (n = 20 each). Patients received either remimazolam (12 mg/kg/h) or propofol (3 μg/mL, TCI), along with remifentanil for inducing anesthesia. We recorded the blood pressure, heart rate (HR), and estimated continuous cardiac output (esCCO) using the pulse wave transit time. The primary outcome was the maximum change in mean arterial pressure (MAP) after induction. Secondary outcomes included changes in HR, cardiac output (CO), and stroke volume (SV).ResultsMAP decreased after induction of anesthesia in both groups, without significant differences between the groups (− 41.1 [16.4] mmHg and − 42.8 [10.8] mmHg in remimazolam and propofol groups, respectively; mean difference: 1.7 [95% confidence interval: − 8.2 to 4.9]; p = 0.613). Furthermore, HR, CO, and SV decreased after induction in both groups, without significant differences between the groups. Remimazolam group had significantly shorter time until loss of consciousness than propofol group (1.7 [0.7] min and 3.5 [1.7] min, respectively; p < 0.001). However, MAP, HR, CO, and SV were not significantly different between the groups despite adjusting time until loss of consciousness as a covariate. Seven (35%) and 11 (55%) patients in the remimazolam and propofol groups, respectively, experienced hypotension (MAP < 65 mmHg over 2.5 min), without significant differences between the groups (p = 0.341).ConclusionsHemodynamics were not significantly different between remimazolam and target-controlled propofol groups during induction of anesthesia. Thus, not only the choice but also the dose and usage of anesthetics are important for hemodynamic stability while inducing anesthesia. Clinicians should monitor hypotension while inducing anesthesia with remimazolam as well as propofol.Trial registrationUMIN-CTR (UMIN000045612).

Hemodynamic Comparison between the Avalus and the Perimount Magna Ease Aortic Bioprosthesis up to 5 Years.

We aimed to compare hemodynamic performance of the Avalus (Medtronic) and the Perimount Magna Ease (PME, Edwards Lifesciences) bioprosthesis up to 5 years by serial echocardiographic examinations. In patients undergoing aortic valve replacement, 58 received PME prostheses between October 2007 and October 2008, and another 60 received Avalus prostheses between October 2014 and November 2015. To ensure similar baseline characteristics, we performed a propensity score matching based on left ventricular ejection fraction, age, body surface area, and aortic annulus diameter measured by intraoperative transesophageal echocardiography. Thereafter, 48 patients remained in each group. Mean age at operation was 67 ± 6 years and mean EuroSCORE-II was 1.7 ± 1.1. Both values did not differ significantly between the two groups. At 1 year the mean pressure gradient (MPG) was 15.4 ± 4.3 mm Hg in the PME group and 14.7 ± 5.1 mm Hg in the Avalus group (p = 0.32). The effective orifice area (EOA) was 1.65 ± 0.45 cm2 in the PME group and 1.62 ± 0.45 cm2 in the Avalus group (p = 0.79). At 5 years the MPG was 16.6 ± 5.1 mm Hg in the PME group and 14.7 ± 7.1 mm Hg in the Avalus group (p = 0.20). The EOA was 1.60 ± 0.49 cm2 in the PME group and 1.51 ± 0.40 cm2 in the Avalus group (p = 0.38). Five-year survival was 88% in the PME group and 91% in the Avalus group (p = 0.5). In the PME group, there were no reoperations on the aortic valve, whereas in the Avalus group three patients required a reoperation due to endocarditis. Both bioprostheses exhibit similar hemodynamic performance during a 5-year follow-up.

Comparison of hemodynamics and root configurations between remodeling and reimplantation methods for valve-sparing aortic root replacement: a pulsatile flow study

PurposeTo compare the characteristics of reimplantation (RI) using grafts with sinuses and remodeling (RM) with/without external suture annuloplasty using a pulsatile flow simulator.MethodsPorcine aortic roots were obtained from an abattoir, and six models of RM and RI with sinuses were prepared. External suture annuloplasty (ESA) was performed in the RM models to decrease the root diameter to 22 mm (RM-AP22) and 18 mm (RM-AP18). Valve models were tested at mean pulsatile flow and aortic pressure of 5.0 L/min and 120/80 (100) mmHg, respectively, at 70 beats/min. The forward flow, regurgitation, leakage, backflow rates, valve-closing time, and mean and peak pressure gradient (p-PG) were evaluated. Root configurations were examined using micro-computed tomography (micro-CT).ResultsThe backflow rate was larger in the RM models than in the RI models (RI: 8.56% ± 0.38% vs. RM: 12.64% ± 0.79%; p < 0.01). The RM-AP and RI models were comparable in terms of the forward flow, regurgitation, backflow rates, p-PG, and valve-closing time. The analysis using a micro-CT showed a larger dilatation of the sinus of the Valsalva in the RM groups than in the RI group (Valsalva: RI, 26.55 ± 0.40 mm vs. RM-AP22, 31.22 ± 0.55 mm [p < 0.05]; RM-AP18, 31.05 ± 0.85 mm [p < 0.05]).ConclusionsRM with ESA and RI with neo-sinuses showed comparable hemodynamics. ESA to RM reduced regurgitation.

Hemodynamic and Clinical Outcomes of Milrinone Compared to Dobutamine in Cardiogenic Shock: A-Systematic Review and Meta-Analysis

Background&#x0D; Despite years of clinical experience with the two most commonly used inotropes i.e dobutamine and milrinone, in the cardiogenic shock setting, there is a lack of head-to-head comparison between inotropes in cardiogenic shock. We conducted a systematic review and meta-analysis on the comparison of hemodynamic and clinical effects of dobutamine and milrinone in cardiogenic shock.&#x0D; Methods&#x0D; A comprehensive literature search using PubMed and Scopus was performed. Among 40 studies retrieved from the database, 3 studies were included for hemodynamic comparison outcome and 2 studies for clinical outcomes. &#x0D; Results&#x0D; Three studies with 101 patients were included for hemodynamic analysis and two studies with 146 patients for clinical analysis. We observed no significant difference between cardiac index, pulmonary capillary wedge pressure, and mean arterial pressure at 1 hour after milrinone and dobutamine administration. However, there is significantly lower mPAP after milrinone infusion compared to dobutamine (mean difference -8,7 (-9,97 to -7,43) mmHg, p&lt;0,01). We also observed no significant difference in in-hospital mortality but significantly shorter ICU length of stay in the milrinone group (mean difference -1 (-1,92 to -0,08) days).&#x0D; Conclusion&#x0D; Administration of milrinone resulted in lower PA pressure and shorter ICU LOS compared to dobutamine in patients with cardiogenic shock.

Comparison of hemodynamics in biological surgical aortic valve replacement and transcatheter aortic valve implantation: An in-silico study.

In aortic valve replacement (AVR), the treatment strategy as well as the model and size of the implanted prosthesis have a major impact on the postoperative hemodynamics and thus on the clinical outcome. Preinterventional prediction of the hemodynamics could support the treatment decision. Therefore, we performed paired virtual treatment with transcatheter AVR (TAVI) and biological surgical AVR (SAVR) and compared hemodynamic outcomes using numerical simulations. 10 patients with severe aortic stenosis (AS) undergoing TAVI were virtually treated with both biological SAVR and TAVI to compare post-interventional hemodynamics using numerical simulations of peak-systolic flow. Virtual treatment procedure was done using an in-house developed tool based on position-based dynamics methodology, which was applied to the patient's anatomy including LVOT, aortic root and aorta. Geometries were automatically segmented from dynamic CT-scans and patient-specific flow rates were calculated by volumetric analysis of the left ventricle. Hemodynamics were assessed using the STAR CCM+ software by solving the RANS equations. Virtual treatment with TAVI resulted in realistic hemodynamics comparable to echocardiographic measurements (median difference in transvalvular pressure gradient [TPG]: -0.33 mm Hg). Virtual TAVI and SAVR showed similar hemodynamic functions with a mean TPG with standard deviation of 8.45 ± 4.60 mm Hg in TAVI and 6.66 ± 3.79 mm Hg in SAVR (p=0.03) while max. Wall shear stress being 12.6 ± 4.59 vs. 10.2 ± 4.42 Pa (p=0.001). Using the presented method for virtual treatment of AS, we were able to reliably predict post-interventional hemodynamics. TAVI and SAVR show similar hemodynamics in a pairwise comparison.

Comparison of haemodynamics in carotid endarterectomy: primary closure versus patch angioplasty

We investigated differences in haemodynamic forces between carotid arteries that underwent primary closure (PC) or patch angioplasty (PA) using computational fluid dynamics (CFD). A total of 30 subjects were enrolled in this study, consisting of 10 subjects who underwent PC, 10 who underwent PA and 10 healthy subjects. Three-dimensional models of carotid arteries were reconstructed using patient-specific computed tomography angiography images. The conventional Navier-Stokes, continuity equation and constitutive stress-strain law with a stabilized Petrov-Galerkin scheme were solved with Newtonian and incompressible assumptions. The boundary conditions employed patient-specific velocity profiles as the inflow and lumped parameters of the three-element Windkessel model as the outflow with a rigid wall assumption. Thus, the CFD results exhibited good agreement with measurements from the subjects (r = .78). The carotid arteries of the PC group were exposed to abnormal haemodynamic forces related to building atherosclerosis in a smaller (p .05) to healthy arteries. The morphological characteristics of the carotid artery were significantly associated with the area exposed to abnormal haemodynamic forces. We identified that abnormal haemodynamic forces could be avoided by selecting appropriate surgical techniques that produce less bifurcation expansion.