Hemodynamic Studies Research Articles

A hemodynamic study of blood flow models on various stent graft configurations during aorto-iliac reconstruction.

To compare the hemodynamic performance of three (Bottom Up non-ballet, Top-Down non-ballet, Top Down ballet) idealized stent graft configurations used during endovascular repair of abdominal aortic aneurysms, under the influence of various rheological models. Ten rheological models are assumed and a commercial finite volume solver is employed for the simulation of blood flow under realistic boundary conditions. An appropriate mesh convergence study is performed and five hemodynamic variables are computed: the time average wall shear stress (TAWSS), oscillatory shear index (OSI), relative residence time (RRT), endothelial cell activation potential and displacement force (DF) for all three configurations. The choice of blood flow model may affect results, but does not constitute a significant determinant on the overall performance of the assumed stent grafts. On the contrary, stent graft geometry has a major effect. Specifically, the Bottom Up non-ballet type is characterized by the least favorable performance presenting the lowest TAWSS and the highest OSI, RRT and ECAP values. On the other hand, the Top Down ballet type presents hemodynamic advantages yielding the highest TAWSS and lowest OSI, RRT and ECAP average values. Furthermore, the ballet type is characterized by the lowest DF, although differences observed are small and their clinical relevance uncertain. The effect of the assumed rheological model on the overall performance of the grafts is not significant. It is thus relatively safe to claim that it is the type of stent graft that determines its overall performance rather than the adopted blood flow model.

Hemodynamic Study of Cerebral Arteriovenous Malformation: Newtonian and Non-Newtonian Blood Flow

ObjectiveArteriovenous malformation is a disease of the vascular system that occurs mainly in the cerebral arteries and spine. Numerical simulation as a powerful method is used to investigate the Cerebral Arteriovenous Malformation hemodynamic after occlusion of the abnormality step by step by embolization. MethodsThe CT Angiographic imaging data of two patients are used and a geometric model is extracted by the Mimics software. Numerical simulation of blood flow is performed in both Newtonian and non-Newtonian models. The Navier–Stokes, and continuity governing equations are solved by finite element method using the COMSOL Multiphysics software (the commercial computational fluid dynamics (CFD) simulation software). To validate the numerical results, the real data on blood flow rate in the feeding artery and draining veins are used, as well as angiographic images at different times. ResultsRegarding the comparison of pressure contours for different occlusions of 0, 30, 50, and 90%, by increasing the amount of occlusion in the nidus, there is an increase in the blood pressure. Regarding the comparison of the blood flow velocity in the feeding artery, draining veins, and inside the AVM nidus for Newtonian and non-Newtonian models, there is a significant difference between these two simulations in vessels with smaller dimensions (such as vessels inside the nidus). ConclusionBy increasing the amount of nidus occlusion, the blood pressure is increased, so the blood supply process is better. According to a significant difference between the Newtonian and non-Newtonian simulations in vessels with smaller dimensions (such as vessels inside the nidus), therefore, non-Newtonian simulation should be done for different occlusions of 30, 50, and 90%.

Hepatic hemodynamic study: More than just HVPG measurement

Evaluation and staging of liver disease is essential in the clinical decision-making process of liver tumors. The severity of portal hypertension (PH) is the main prognostic factor in advanced liver disease. Performing an accurate hepatic venous pressure gradient (HVPG) measurement is not always possible, especially when veno-venous communications are present. In those complex cases, a refinement in HVPG measurement with a thorough evaluation of each of the components of PH is mandatory. We aimed at describing how some technical modifications and complementary procedures may contribute to an accurate and complete clinical evaluation to improve therapeutic decisions.

Abstract WMP116: A P2X4 Inhibitor Dramatically Suppresses the Progression of Cervical Internal Carotid Artery Stenosis - An Attempt to Develop a Therapeutic Agent for Carotid Artery Stenosis Focusing on the Role of Hemodynamic Factors-

Introduction: Medical treatment of internal carotid artery stenosis consists of treatment of underlying conditions such as hypertension, dyslipidemia, and diabetes mellitus, as well as antiplatelet therapy. Hemodynamic studies suggest that endothelial cells sense disturbances and stagnation of blood flow caused by vessel geometry, which trigger the progression of stenosis. Similarly, cerebral aneurysms are known to progress due to hemodynamic effects. We have shown in animal studies that inhibition of P2X4 purinoceptor, an endothelial blood flow sensing-related protein, significantly inhibits the development of cerebral aneurysms. In the present study, we examined whether P2X4 disruption can suppress the progression of internal carotid artery stenosis using an animal model of carotid artery stenosis. Methods: Carotid stenosis coils were implanted in the left carotid artery of 7-week-old P2X4(-/-) and (+/+) mice fed a high-cholesterol diet. Four weeks after placement, the carotid arteries were removed and the occlusion rates of the carotid arteries were compared. The expression of known stenosis-related inflammatory factors was also examined by Western blotting. Results: The carotid occlusion rate was significantly lower in the P2X4 gene-deficient mice, with 5 of 16 occlusions, compared with 9 of 13 occlusions in the control group (p=0.0394, Student's t-test). The expression levels of MCP-1, COX-2, TNFα, and IL-1β were significantly increased in the carotid arteries of P2X4(+/+) mice with the coil compared to the non-operated group (p=0.0073, 0.0012, 0.0016, 0.0031, respectively, Wilcoxon's signed rank test). The carotid arteries of P2X4(-/-) mice with coils showed significantly lower expression of all of the above compared to those of P2X4(+/+) mice (p=0.0233, 0.0020, 0.0098, 0.0046, respectively). Conclusions: These results suggest that inhibition of endothelial blood flow sensing by P2X4 disruption may have reduced the progression of carotid artery stenosis by suppressing the expression of a group of inflammatory factors associated with carotid artery stenosis. This may lead the way to new drug therapies for carotid artery stenosis.

Hemodynamic study on the therapeutic effects of varying diameter embolic coils in the treatment of intracranial aneurysms.

Endovascular coiling is the predominant method for treating cerebral aneurysms. Extensive reports on selecting coil length, hardness, and material are available. However, the impact of coil diameter on postoperative outcomes remains unclear. This study enrolled six personalized geometric models of intracranial aneurysms: three bifurcation aneurysms and three sidewall aneurysms. Four coil models were constructed by changing the coil diameter. Coil embolization was simulated using the finite element method. Computational fluid dynamics was used to characterize hemodynamics in the aneurysms after embolization. Evaluation parameters included velocity reduction, wall shear stress (WSS), low WSS (LWSS), oscillatory shear index (OSI), relative residence time (RRT), and residual flow volume in the aneurysms. At the peak time (t = 0.17 s), the proportion of LWSS area in bifurcation aneurysms increase with the rise in coil diameter: 0.8D, 71.28 ± 12.62% versus 1D, 74.97 ± 19.17% versus 1.2D, 78.88 ± 18.56% versus 1.4D, 84.00 ± 11.53% (mean ± SD). The proportion of high OSI area decreases as the coil diameter increases: 0.8D, 4.41% ± 2.82% versus 1.0D, 3.78 ± 3.33% versus 1.2D, 2.28% ± 1.77% versus 1.4D, 1.58% ± 1.11% (mean ± SD). The proportion of high RRT area increases as the coil diameter rises: 0.8D, 3.40% ± 1.68% versus 1.0D, 7.67 ± 4.12% versus 1.2D, 9.84% ± 9.50% versus 1.4D, 22.29% ± 14.28% (mean ± SD). Side wall aneurysms do not exhibit the aforementioned trend. Bifurcation aneurysms plugged with a coil of 1.4 times the diameter have the largest RFVs (<10 mm/s) within the group. Aforementioned patterns are not found in sidewall aneurysms. In the treatment of aneurysms with coiling, varying coil diameters can result in different hemodynamic environments within the aneurysm. Larger coil diameters have improved hemodynamic performance for bifurcation aneurysms. However, coil diameter and embolization effectiveness have no significant relationship for sidewall aneurysms.

A comparative study of altered hemodynamics in iliac vein compression syndrome.

Introduction: Iliac vein compression syndrome (IVCS) is present in over 20% of the population and is associated with left leg pain, swelling, and thrombosis. IVCS symptoms are thought to be induced by altered pelvic hemodynamics, however, there currently exists a knowledge gap on the hemodynamic differences between IVCS and healthy patients. To elucidate those differences, we carried out a patient-specific, computational modeling comparative study. Methods: Computed tomography and ultrasound velocity and area data were used to build and validate computational models for a cohort of IVCS (N = 4, Subject group) and control (N = 4, Control group) patients. Flow, cross-sectional area, and shear rate were compared between the right common iliac vein (RCIV) and left common iliac vein (LCIV) for each group and between the Subject and Control groups for the same vessel. Results: For the IVCS patients, LCIV mean shear rate was higher than RCIV mean shear rate (550 ± 103s-1 vs. 113 ± 48s-1, p = 0.0009). Furthermore, LCIV mean shear rate was higher in the Subject group than in the Control group (550 ± 103s-1 vs. 75 ± 37s-1, p = 0.0001). Lastly, the LCIV/RCIV shear rate ratio was 4.6 times greater in the Subject group than in the Control group (6.56 ± 0.9 vs. 1.43 ± 0.6, p = 0.00008). Discussion: Our analyses revealed that IVCS patients have elevated shear rates which may explain a higher thrombosis risk and suggest that their thrombus initiation process may share aspects of arterial thrombosis. We have identified hemodynamic metrics that revealed profound differences between IVCS patients and Controls, and between RCIV and LCIV in the IVCS patients. Based on these metrics, we propose that non-invasive measurement of shear rate may aid with stratification of patients with moderate compression in which treatment is highly variable. More investigation is needed to assess the prognostic value of shear rate and shear rate ratio as clinical metrics and to understand the mechanisms of thrombus formation in IVCS patients.

Impact of Interventricular Interaction on Ventricular Function: Insights From Right Ventricular Pressure-Volume Analysis

BackgroundInterventricular interactions may be responsible for the decline in ventricular performance observed in various disease states that primarily affect the contralateral ventricle. ObjectivesThis study sought to quantify the impact of such interactions on right ventricular (RV) size and function using clinically stable individuals with left ventricular assist devices (LVADs) as a model for assessing RV hemodynamics while LV loading conditions were acutely manipulated by changing device speed during hemodynamic optimization studies (ie, ramp tests). MethodsThe investigators recorded RV pressure-volume loops with a conductance catheter at various speeds during ramp tests in 20 clinically stable HeartMate3 recipients. ResultsWith faster LVAD speeds and greater LV unloading, indexed RV end-diastolic volume increased (72.28 ± 15.07 mL at low speed vs 75.95 ± 16.90 at high speed; P = 0.04) whereas indexed end-systolic volumes remained neutral. This resulted in larger RV stroke volumes and shallower end-diastolic pressure-volume relationships. Concurrently, RV end-systolic pressure decreased (31.58 ± 9.75 mL at low speed vs 29.58 ± 9.41 mL at high speed; P = 0.02), but contractility, as measured by end-systolic elastance, did not change significantly. The reduction in RV end-systolic pressure was associated with a reduction in effective arterial elastance from 0.65 ± 0.43 mm Hg/mL at low speed to 0.54 ± 0.33 mm Hg/mL at high speed (P = 0.02). ConclusionsInterventricular interactions resulted in improved RV compliance, diminished afterload, and did not reduce RV contractility. These data challenge the prevailing view that interventricular interactions compromise RV function, which has important implications for the understanding of RV-LV interactions in various disease states, including post-LVAD RV dysfunction.

Hemodynamic response to inhaled nitric oxide in patients with pulmonary hypertension and chronic kidney disease: A retrospective cohort study.

Pulmonary hypertension (PH) associated with chronic kidney disease (CKD) (PH-CKD) affects approximately 20%-40% of CKD patients and is associated with increased morbidity and mortality. PH and CKD are both pathophysiologically associated with nitric oxide (NO) deficiency. The NO pathway, an important therapeutic domain in pulmonary arterial hypertension (PAH), is an intriguing but unexplored target in PH-CKD. We sought to improve understanding of the clinical significance of the NO pathway in patients with PH-CKD by assessing the hemodynamic response to inhaled NO (iNO) during right heart catheterization (RHC). In this retrospective cohort study, patients with diagnosis codes of PH and stage IV/V CKD or end-stage renal disease and estimated glomerular filtration rate < 60 mL/min/body surface areawho underwent RHC and hemodynamic drug study between July 2011 and June 2021 were eligible. Patients with mean pulmonary artery pressure (mPAP) > 20 mmHg and pulmonary vascular resistance (PVR) > 3Wood unitswere included. The final cohort included 37 patients (45.9% female, mean age 72.5 ± 9.7 years). A total of 56.7%of the cohort (21/37) had precapillary PH, while 43.2% (16/37) had combined precapillary postcapillary PH (Cpc-PH). Median survival was 3.1 years after RHC. iNO was associated with a significant decrease in both mPAP and PVR. Hemodynamic changes in mPAP and PVR were similar in precapillary and Cpc-PH groups. Among a small subset (n = 14) who were subsequently treated with PAH-targeted therapy, treatment response was mixed and did not reveal significant benefit. Further studies are warranted to better define the potential role of PAH therapy in PH-CKD.

Pulmonary vascular pressure respiratory swings in COPD and ILD candidates for lung transplantation: Large but different.

We analyzed the effect of respiratory swings on interpreting intravascular pulmonary vascular pressures (PVPs) in chronic obstructive pulmonary disease (COPD) and interstitial lung disease (ILD) candidates for lung transplantation (LTx) and the role of the alterations in pulmonary function tests on the dynamic respiratory variations. Twenty-eight consecutive patients were included. All patients underwent a complete hemodynamic study (right atrial, mean pulmonary arterial, and pulmonary arterial occlusion pressures [RAP, mPAP, and PAOP]-) and pulmonary function testing (force vital capacity [FVC], forced expiratory volume in the first second [FEV1], and residual volume [RV]). A subgroup of 10 patients underwent simultaneous esophageal pressure (PES). All hemodynamic parameters and PES were collected during apnea after an unforced expiration (ee) and during spontaneous breathing averaging five respiratory cycles (mrc). The respiratory swing (osc) was estimated as the difference between maximum-minimum values of pressures during the respiratory cycle. Intravascular RAPee, mPAPee, and PAOPee were higher than mrc values (p < 0.05), leading to 11% of pulmonary hypertension (PH) misdiagnosis and 37% of postcapillary PH misclassification. PAOPosc of COPD was higher than ILD patients and RAPosc (p < 0.05). Only PAOPosc correlated with FVC, FEV1, and RV (p < 0.05). ILD PESmrc was lower than COPD (p < 0.05), and it was associated with a significantly higher transmural than intravascular RAPmrc, mPAPmrc, and PAOPmrc. PESmrc was significantly correlated with FVC. Transmural mPAPmrc and PAOPmrc readings determined around 20% of reclassification of the patients compared to ee measurements. Candidates for LTx showed large respiratory swings in PVP, which were correlated with pulmonary function alterations. mrc PVP would be more closely approximated to the true transmural PVP leading to PH reclassification. Adjusting PVP for PES should be considered in COPD and ILD candidates of LTx with severe alterations in pulmonary functional tests and suspicion of a PESmrc far from 0. PES respiratory swings could be different in ILD to COPD patients.

In search of a marker of altered cerebrovascular function in hypertension: Analysis of the fractional amplitude of low-frequency fluctuations in UK Biobank resting state fMRI data

The selfish brain mechanism proposes that in some patients with impaired cerebral blood flow (CBF) or cerebrovascular function, hypertension may develop as a compensatory mechanism that aims to maintain CBF by increasing systemic blood pressure through an increase in cardiovascular sympathetic tone. The amplitude of low frequency fluctuations (ALFF) in the resting state blood oxygenation level dependent (BOLD) functional MRI signal has been previously posited as an index of cerebrovascular reactivity.We investigated whether regional fractional ALFF (fALFF) differs between 2054 hypertensives and 1724 normotensives using data from the UK Biobank dataset. Our primary hypothesis was that cerebrovascular function in the medulla and other regions involved in sympathetic regulation differs between hypertensives and normotensives, and that this is reflected by regional variations in fALFF.There is a significant regional variation in fALFF (F(14) =1126.17, p < 2 × 10−16, partial η2 = 0.22), but this regional variation does not differ between hypertensives and normotensives (F(14) = 0.23, p = 0.99, partial η2 = 8 × 10−5).Prospective longitudinal studies of cerebral haemodynamics in hypertensives and normotensives are required to further investigate the selfish brain mechanism.

The Elusive Hypertrophy of the Python Heart.

The Burmese python, one of the world's largest snakes, has reached celebrity status for its dramatic physiological responses associated with digestion of enormous meals. The meals elicit a rapid gain of mass and function of most visceral organs, particularly the small intestine. There is also a manyfold elevation of oxygen consumption that demands the heart to deliver more oxygen. It therefore made intuitive sense when it was reported that the postprandial response entailed a 40% growth of heart mass that could accommodate a rise in stroke volume. Many studies, however, have not been able to reproduce the 40% growth of the heart. We collated published values on postprandial heart mass in pythons, which include several instances of no change in heart mass. On average, the heart mass is only 15% greater. The changes in heart mass did not correlate to the mass gain of the small intestine or peak oxygen consumption. Hemodynamic studies show that the rise in cardiac output does not require increased heart mass but can be fully explained by augmented cardiac filling and postprandial tachycardia. Under the assumption that hypertrophy is a contingent phenomenon, more recent experiments have employed two interventions such as feeding with a concomitant reduction in hematocrit. The results suggest that the postprandial response of the heart can be enhanced, but the 40% hypertrophy of the python heart remains elusive.

Impact of Multi-Grade Localized Calcifications on Aortic Valve Dynamics under Helical Inflow: A Comparative Hemodynamic Study

This study investigates the hemodynamic impacts of localized aortic valve calcification, utilizing immersed boundary-finite element (IBFE) method simulations with realistic inflow patterns of uniform and helical blood flow from the left ventricular outflow tract (LVOT). We modeled the aortic valve leaflets with varying grades of calcification, assessing their influence on valve performance, including transvalvular hemodynamics, wall shear stress (WSS) indices, and vortical structures. The findings highlighted that calcification significantly restricts leaflet motion, diminishes the orifice area, disrupts flow efficiency, and consequently increases the left ventricular workload. Advanced calcification resulted in elevated WSS, especially at the leaflet tips, which indicates a heightened risk of endothelial damage and further calcification. Asymmetrical calcifications redirect flow towards the ascending aorta wall, potentially inducing structural damage and increased stress on the remaining healthy leaflets. Calcification was also found to alter the naturally occurring helical blood flow patterns, affecting the system’s fluid transport efficiency and possibly contributing to cardiovascular disease progression. The study revealed a significant alteration in vortex formation, with calcification causing distorted and complex vortex structures, which may influence the dynamics of blood flow and valve function. These insights into the hemodynamic changes induced by calcification contribute to a better understanding of the progression of aortic valve diseases and could inform more effective diagnostic and treatment strategies.

Artificial intelligence and hemodynamic studies in optical coherence tomography angiography for diabetic retinopathy evaluation: A review.

Diabetic retinopathy (DR) is a rapidly emerging retinal abnormality worldwide, which can cause significant vision loss by disrupting the vascular structure in the retina. Recently, optical coherence tomography angiography (OCTA) has emerged as an effective imaging tool for diagnosing and monitoring DR. OCTA produces high-quality 3-dimensional images and provides deeper visualization of retinal vessel capillaries and plexuses. The clinical relevance of OCTA in detecting, classifying, and planning therapeutic procedures for DR patients has been highlighted in various studies. Quantitative indicators obtained from OCTA, such as blood vessel segmentation of the retina, foveal avascular zone (FAZ) extraction, retinal blood vessel density, blood velocity, flow rate, capillary vessel pressure, and retinal oxygen extraction, have been identified as crucial hemodynamic features for screening DR using computer-aided systems in artificial intelligence (AI). AI has the potential to assist physicians and ophthalmologists in developing new treatment options. In this review, we explore how OCTA has impacted the future of DR screening and early diagnosis. It also focuses on how analysis methods have evolved over time in clinical trials. The future of OCTA imaging and its continued use in AI-assisted analysis is promising and will undoubtedly enhance the clinical management of DR.

GİRİŞ HIZ PROFİLİ VE GİRİŞ UZUNLUĞUNUN ABDOMİNAL AORT ANEVRİZMASI HEMODİNAMİĞİ SİMÜLASYONLARINA ETKİSİ

In computational Abdominal Aortic Aneurysm (AAA) hemodynamics studies, along with adjusting the problem geometry, mesh, transport, turbulence and rheology models; setting up boundary conditions (BC) is also a very important step which affect the reliability and accuracy of the hemodynamic assessment. The transient effects of physiological flow are well described by the Womersley profile, though its application might be difficult due to the complex nature of functions involved. Conversely, in literature, studies utilizing Plug or Parabolic profiles as inlet boundary conditions generally requires large entrance lengths to obtain the exact characteristics of the Womersley profile. In the current study, the differences arising between those boundary conditions, Womersley, Parabolic and Plug, with different entrance lengths, L_(ent )=D,3D and 11D, are examined by comparing the results with a Base condition, which is a solution obtained with ensured fully-developed flow before entering the aneurysm sac at two physiological flow conditions with mean Reynolds numbers, 〖Re〗_m=340 and 1160. The results reveal that with increasing mean flow rate, applying the complex Womersley equation might not be necessary. For the inlet flow waveform with 〖Re〗_m=1160, the Parabolic profile can be used instead of the Womersley profile by supplying an entrance length L_(ent )= 3D. On the other hand, the Plug profile requires an entrance length at least L_(ent )= 11D to replicate the Base condition for waveform with 〖Re〗_m=340.

Comparison of milrinone versus dobutamine on invasive haemodynamics in patients with advanced heart failure on home inotropes

Abstract Background Home inotropic support is an established bridge to cardiac transplantation in patients with advanced heart failure. Milrinone, a phosphodiesterase 3 inhibitor, preferentially vasodilates pulmonary vasculature, thus is often chosen over dobutamine in patients with concomitant pulmonary hypertension. However, there is a paucity of data on the haemodynamic effects of milrinone in the pre-cardiac transplant population. Purpose We sought to examine the haemodynamic effects of milrinone vs. dobutamine out to 3 months in patients with advanced heart failure awaiting cardiac transplantation. Methods Patients in the home inotrope program at a quaternary referral centre from January 2000 to May 2022 were included. Retrospective analysis of echocardiographic and invasive haemodynamic studies via right heart catheterisation were performed at baseline (prior to commencement of inotrope), at 30 days (30D) and 3 months (3m). Results From a total of 119 patients, 57 were on milrinone and 62 on dobutamine. Non-ischaemic cardiomyopathies of various aetiologies accounted for 67%, while ischaemic cardiomyopathies accounted for 33%. Majority of patients were male (79%) with a mean age of 52±13 years. There was a significant increase in LVEF from 21±7% at baseline to 27±14% at 3m in those on dobutamine, p = 0.02. Similar increase in LVEF from 22±8% to 26±13% in the milrinone group did not reach significance, p = 0.43. Comparably, CI increased from 2.0±0.6L/min/m2 at baseline to 2.5±0.9L/min/m2 at 3m in the dobutamine cohort, p = 0.05, and from 2.0±0.7L/min/m2 at baseline to 2.3±0.6L/min/m2 at 3m in the milrinone cohort, p = 0.27. In the dobutamine cohort LVEDD was static from 68±14mm at baseline to 66±21mm at 3m, p = 0.78. LVEDD reduced from 67±11mm to 60± 9mm at 3m in the milrinone group, p = 0.09. Classification of mild right ventricular dysfunction increased from 7% to 18% after 30 days on milrinone, p= 0.2, compared to an increase from 10% to 16% in the dobutamine group, p = 0.47. Mean pulmonary artery pressure (mPAP) reduced from 34±11mmHg to 29±11mmHg at 3m in the milrinone group, p = 0.15. mPAP was static in the dobutamine group from 34±9mmHg at baseline to 34±10mmHg at 3m, p = 0.96. TPG in the milrinone group was 11.9±6.0mmHg to 12.9±6.3mmHg at 30D, with reduction at 3m to 9.6±6.3mmHg, p = 0.26. In the dobutamine group TPG remained static from 10.9±5.7mmHg at baseline to 11.4±5.1mmHg at 30D and 10.9±5.2 at 3m, p = 0.97. Wedge pressure (PCWP) reduced from 22±7mmHg at baseline to 21±7mmHg at 30D to 18±8mmHg at 3m in the milrinone group, p = 0.11. PCWP in the dobutamine group was static at 23±8mmHg at baseline to 24±5mmHg at 30D and 23±6mmHg at 3m, p = 0.92. Conclusion(s) Dobutamine demonstrated a significant increase in LVEF and CI out to 3 months, however milrinone demonstrated a larger improvement in RV function and greater reduction in cardiac and pulmonary pressures as compared to dobutamine. Larger studies are required to confirm these trends.Figure 1

Usefulness of cardiopulmonary exercise test to detect exercise pulmonary hypertension in the post pulmonary embolim follow-up

Abstract Functional impairment is largely reported after symptomatic pulmonary embolism (PE). Chronic thromboembolic pulmonary disease (CTED) refers to the presence of chronic thrombotic pulmonary vascular occlusion in the absence of pulmonary hypertension (PH) at rest but with incipient vasculopathy responsible for exercise limitation. Exercise haemodynamic studies have emerged to detect an abnormal response suggesting an established vasculopathy or an abnormal left ventricular filling pressure. We hypothesized that exercise intolerance due to an abnormal haemodynamic response during exercise might be unmasked by the parameters exhibited at the cardiopulmonary exercise test (CPET) in diagnostic workup after PE in symptomatic patients. Our aim was to correlate the values reached in the CPET pattern with haemodynamic response during exercise right heart catheterization (RHC) in patients with CTED suspicion. Methods We selected symptomatic patients with confirmed perfusion defects in lung scintigraphy despite optimal anticoagulant therapy for a minimum of 3 months after a PE with normal lung function tests. Left heart disease and significant PH were ruled out with RHC (inclusion criteria implied mean pulmonary arterial pressure (mPAP) &amp;lt; 25 mmHg and pulmonary vascular resistance (PVR) &amp;lt; 3 WU and pulmonary arterial wedge pressure (PAWP) ≤15 mmHg). Exercise RHC was performed sequentially 24 hours after CPET. The exercise protocol was the same for both tests. Pulmonary pressure and cardiac output (CO) were collected at each exercise leel. Exercise PH (ex-PH) was considered when mPAP/CO slope &amp;gt;3 mmHg·L−1·min−1. We made a subanalysis according to the new PH criteria (mPAP &amp;gt;20mmHg &amp; PVR &amp;gt; 2 WU at rest). Results 39 patients (median age 52.7 ± 15.7 years, 36% females) were included. 21 (53.8%) showed abnormal haemodynamic behaviour, 6(15.4%) of them due to abnormal PWAP/CO slope. Baseline characteristics are summarized in Table 1. Patients with abnormal exercise response showed worse ventilatory efficiency at exercise: 1) reduced partial end-tidal of carbon dioxide (PetCO2) at the anaerobic threshold (AT) (32.0 Vs 36.4, p=0.001), 2) a steeper VE/CO2 slope (35.6 Vs 30.9, p=0.009) and 3) a higher ventilatory equivalent for CO2 at the AT (35.5 Vs 31.6, p=0.004) compared to the group with normal hemodynamic behaviour. Oxygen consumption at the AT and peak oxygen consumption were slightly decreased without statistically significant differences between groups.Of the global cohort, 11 patients reached new resting PH criteria, and 92% of them showed ex-PH. Ventilatory efficiency showed differences in the subgroup with normal resting hemodynamic values, especially lower PetCO2 at the AT (31.8 Vs 35.0, p=0.008) (Figure 2). Conclusion In the context of persistent dyspnoea after PE, ventilatory inefficiency is a sign of exercise pulmonary hypertension, and CPET could identify patients with abnormal exercise response despite normal hemodynamic values at rest.

Exploring the mechanisms responsible for afterload mismatch in severe aortic stenosis

Abstract Introduction Afterload mismatch (AM) is defined as a reduced ejection fraction (EF) in the setting of severe aortic stenosis (AS) (aortic valve area (AVA) of &amp;lt; 1cm2), but with transaortic pressure gradients in the severe range. The pathomechanism underlying the impaired EF remains unclear, especially with regards to the impact of ventricular hypertrophy and fibrosis, the role of afterload, and the integrity of the intrinsic contractile myocardial strength in AM. This knowledge gap unmasks a lack of understanding into the natural disease progression in AS. Purpose To characterise the morphological and functional contractile mechanics that distinguishes patients with reduced EF from patients with preserved EF in the setting of AS with high transvalvular gradients. Methods A prospective comparative analysis was performed on 21 sequential cases of patients with severe AS, 9 with AM (AVA &amp;lt; 1.0cm2; MG &amp;gt; 40mmHg; EF &amp;lt; 50%) and 12 with normal flow high gradient (NFHG) AS (AVA &amp;lt; 1.0cm2; MG &amp;gt; 40mmHg; EF &amp;gt; 50%). Patients with concomitant valve lesions or previously diagnosed myocardial infarction, were excluded. Myocardial morphology, function and tissue characteristics were evaluated using a) transthoracic echocardiography, b) cardiac magnetic resonance imaging, and c) an invasive hemodynamic study with pressure-volume loop derived data. Results Intrinsic load independent contractile muscle function parameters were similar between AM and NFHG AS (p-value non-significant for cardiac index, dP/dT(max), preload recruitable stroke work slope, end systolic pressure volume relationship slope and Starling contractile index slope). Afterload indices as assessed by peak systolic wall stress and valvuloarterial impedance were significantly higher in AM cases compared to NFHG AS (32.5 vs 19.9 N/cm2; p &amp;lt; 0.01 and 4.8 vs 3.4mmHg/ml; P = 0.05). This was driven by disproportionally higher degrees of valvular stenosis in the AM group (valve area 0.46 vs 0.78cm2; p &amp;lt; 0.01). The AM group expressed a more advanced disease phenotype with more symptoms (NYHA 3.3 vs 2.3; p=0.02), more pulmonary hypertension (50 vs 30mmHg; p=0.04), and more extensive myocardial fibrosis (24% vs 13% of left ventricular mass; p=0.03) (see Figure 1). Neither more severe LVH nor higher degrees of fibrosis in the AM group, was associated with a demonstrable impairment in the intrinsic contractile muscle function. Conclusion Our data suggest that the central problem in AM is related to an excessively increased afterload, primarily driven by more severe valvular stenosis, with preserved intrinsic left ventricular contractile function. AM is characterised by more severe myocardial fibrosis, as a marker of a more advanced disease phenotype, but this did not translate into worse intrinsic contractile muscle function. The known time dependence of progressive valvular stenosis and myocardial fibrosis would suggest that AM is an intermediate phase between NFHG AS and so-called low flow low gradient severe AS.A more advanced phenotype

Abstract 19112: Hemodynamic Optimization of Left Ventricular Assist Devices During Right Heart Catheterization Ramp Studies

Background: Studies have shown that hemodynamic LVAD ramp studies can be used to optimize speeds and improve clinical outcomes, yet these studies lack external validation. Methods: 470 LVAD patients, including 3 LVAD subtypes, were retrospectively analyzed and 53 ramp studies were identified. Measurements (RA, mean PA, PCWP, and CI) were taken at speeds +/- 20% of the manufacturer recommended set speed for HM2, HM3, and HVAD devices. Primary outcomes were all-cause and heart failure (HF) hospitalizations in the 6-month period pre- and post-ramp study. Secondary outcomes included final LVAD speed and hemodynamic measurements following ramp study. Time to first hospitalization and cumulative incidence rate of all-cause and HF hospitalization were reported. Results: Baseline characteristics of 53 studies included: mean age of 60.1 (+/- 10.9), 84.9% male, 56.6% ischemic etiology, 71.7% destination therapy, and average NYHA class and INTERMACS of 2.5 (+/- 0.7) and 5.9 (+/- 1), respectively. 38 of 53 studies (71.7%) showed PCWP decompression &gt;20%, with average PCWP decompression of 51.2% (+/- 21.0%), and CI increase of 22.5% (+/- 18.7%). Optimal LVAD speeds were chosen to maintain CI &gt; 2.2, PCWP &lt; 15 and minimize RAP, in the absence of suction events. 31 (58.5%) of studies resulted in an LVAD speed change and 16 (30.2%) of studies resulted in diuretic change. All-cause and HF hospitalizations were significantly decreased in the 6-months following ramp studies compared the 6-months pre-ramp (total days hospitalized for all causes: 12.0 vs 26.6, p=0.002; total days hospitalized for HF, 4.8 vs 22.1, p=0.0003). Speed changes were associated with a nonsignificant improvement in time to first hospitalization. Conclusion: This externally validates previous data suggesting that LVAD hemodynamic ramp studies decrease hospitalizations. Larger studies and longer follow up may elucidate specific hemodynamic targets to improve mortality and further reduce rehospitalizations.

Abstract 17689: Distal Ventricular Pacing for Drug-Refractory Mid-Cavity Obstructive Hypertrophic Cardiomyopathy: A Randomized, Placebo-Controlled Trial of Personalized Pacing

Introduction: Patients with refractory symptomatic left ventricular (LV) mid-cavity obstructive (LVMCO) hypertrophic cardiomyopathy (HCM) have extremely limited therapeutic options. Hypothesis: We hypothesized that site-specific-pacing would induce regionalized contractile dyssynchrony to reduce LVMCO gradients and improve symptoms. Methods: Symptomatic-drug-refractory LVMCO patients were recruited for a randomized blinded trial of personalized prescription of pacing (PPoP). Multiple LV and apical RV pacing sites were assessed during invasive hemodynamic study. Patient-specific optimal pacing site and atrioventricular (AV) delays were selected on basis of LVMCO gradient reduction and pacing parameters. Patients were randomized to 6 months active or back-up pacing in cross-over design. Primary outcome examined invasive gradient change with PPoP. Secondary outcomes assessed quality of life and exercise. Results: A total of 17 patients were recruited; 16 met primary endpoints. Baseline NYHA was 3±0.6 despite medical therapy. Hemodynamic effects were assessed during pacing at RV apex and a mean of 8 LV sites (range 4-16). Optimal PPoP was achieved via LV pacing in 14 (88%) patients and RV apex in 2. Mean baseline gradient 80±29 mmHg fell to 31±21 mmHg with PPoP (p&lt;0.0001). Cardiac vein perforation occurred in one case, and 15 patients entered into cross-over; 2 withdrawals occurred during cross-over (myocardial infarction, persistent atrial fibrillation). Of the 13 completing cross-over, 9 (69%) chose active pacing as their preferred setting. PPoP was associated with better 6-minute walking test performance (329±100 vs 286±106 meters, p=0.018); other outcome measures also indicated benefit with PPoP. Conclusions: In a randomized placebo-controlled trial, PPoP reduces obstruction and improves exercise performance in severely symptomatic LVMCO patients. A personalized approach to pacing site selection is a key component of this novel therapy.

Abstract 14114: An Extreme Case of Calcific Constrictive Pericarditis

Introduction: Constrictive pericarditis (CP) can lead to cardiac dysfunction and a range of clinical symptoms. However, differentiating it from conditions like restrictive cardiomyopathy can be challenging due to the overlapping features. Case Presentation: We present a case of a 61-year-old female with a history of atrial flutter and subsequent atrial fibrillation, experiencing worsening dyspnea on exertion, lip cyanosis, and upper abdominal constriction. Extensive diagnostic workup, including Echo, CT scan, and cardiac MRI, revealed severe biatrial enlargement, ventricular interdependence, elevated filling pressures, reduced cardiac output, and extensive pericardial thickening and calcifications ( Figures 1.a and 1.b ). These findings supported the diagnosis of extensive CP. Discussion: CP is often missed and delayed in diagnosis due to its complex hemodynamics and the non-specific symptoms. Typically, the initial imaging modality to be performed is an Echo. Specific findings such as dilated vena cava, preserved tissue velocity with annuls paradoxus, abnormal respiratory septal shift, and respiratory variations in mitral/tricuspid inflow should be first clues for potential diagnosis. Furthermore, evaluation of the hepatic vein with diastolic flow reversal during expiration is a key finding. Lack of respiratory variation in the SVC is also important. Cardiac CT will assess pericardial thickness and calcification, while cardiac MRI is key for the diagnosis by showing the pericardial thickness and fibrosis as well as the septal respiratory shift and venous congestion. An invasive hemodynamic study might be required if imaging is inconclusive. this patient’s presentation, imaging findings, exercise test results and collectively supported considering radical pericardiectomy. Conclusions: This report highlights the diagnostic challenges related to CP and the importance employing a multimodality imaging approach for accurate diagnosis.