Significant Hemodynamic Alterations Research Articles

Caffeine pharmacokinetics following umbilical vein injection during delayed cord clamping in preterm lambs.

Spontaneous breathing during and after delayed cord clamping (DCC) stabilizes cardiopulmonary transition at birth. Caffeine stimulates breathing and decreases apnea in premature newborns. We evaluated the pharmacokinetics and physiological effects of early caffeine administration-direct injection into the umbilical vein (UV) during DCC or administered through a UV catheter (UVC) after delivery. Eighteen extremely premature lambs (125-127d, term gestation 145d) were exteriorized and instrumented. Lambs received caffeine-citrate at high (40 mg/kg) or standard-dose (20 mg/kg) via direct UV (DUV) injection during DCC, or via the UVC. Mean peak plasma caffeine concentrations were lower with high-dose DUV compared to UVC (18 ± 4.3 vs. 46 ± 12 mg/L, p < 0.05). With standard-dose caffeine, mean peak plasma levels were 7.48 ± 2.6 with DUV and 28.73 ± 9.4 mg/L with UVC. The volume of distribution was higher in the DUV group compared to UVC (2.5 ± 1.0 vs. 0.69 ± 0.15 L/kg) with an estimated 39 ± 18% entering the maternal circulation. Maternal peak concentrations were 0.79 ± 0.71 and 1.43 ± 0.74 mg/L with standard and high-dose DUV, respectively. Caffeine injected directly into the UV during DCC is feasible but achieves lower concentrations due to high volume of distribution including maternal circulation. Further trials evaluating DUV caffeine injection should use higher caffeine doses. Respiratory stimulation with early caffeine may reduce the need for intubation in preterm infants. In the preterm lambs, caffeine injection directly into the umbilical vein during delayed cord clamping is feasible. Plasma caffeine concentrations are less than half when administered directly into the umbilical vein during delayed cord clamping compared to administration via an umbilical venous catheter following birth likely attributed to a larger volume of distribution or injection site leak. There were no significant hemodynamic alterations following caffeine injection.

Hemodynamic and morphological differences in cerebral aneurysms between before and after rupture.

Although it has been proposed that aneurysm morphology is different after rupture, detailed research of the morphological changes using 3D imaging acquired before and after rupture has not been conducted because of the difficulty of data collection. Similarly, hemodynamic changes due to morphological alterations after rupture have not been analyzed. The aim of this study was to investigate the changes in morphology and hemodynamics observed after aneurysm rupture. For 21 cerebral aneurysms (21 patients) that ruptured during observation, 3D geometry of the aneurysms and parent arteries were reconstructed based on the angiographic images before and after their rupture. In addition, using the reconstructed geometry, blood flow was simulated by computational fluid dynamics (CFD) analysis. Morphological and hemodynamic parameters were calculated both before and after rupture, and their changes from before to after were compared. In the morphological parameters, statistically significantly higher values were observed after rupture in height (before: 5.5 ± 2.1 mm, after: 6.1 ± 2.0 mm; p < 0.0001), aspect ratio (p = 0.002), aneurysm volume (p = 0.04), and undulation index (p = 0.005). In terms of hemodynamic changes, the mean normalized wall shear stress (NWSS) decreased significantly (before: 5.4 × 10-1 ± 2.9 × 10-1, after: 4.4 × 10-1 ± 2.8 × 10-1; p < 0.001) as well as the other NWSS parameters, including maximum and minimum NWSS, which were associated with stagnant flow due to the morphological changes after rupture. Aneurysm morphology was found to change after rupture into an elongated and irregular geometry, accompanied by an increase in aneurysm volume. These morphological changes were also associated with statistically significant hemodynamic alterations that produced low wall sheer stress by stagnant flow. The authors' results also provide the opportunity to explore and develop a risk evaluation method for aneurysm rupture based on prerupture morphology and hemodynamics by further exploration in this direction.

Effects of Magnesium Sulphate, Dexmedetomidine and Lignocaine on Perioperative Haemodynamic and Postoperative Analgesia in Patients Undergoing Laparoscopic Abdominal Surgeries: A Randomised Clinical Study

Introduction: Laparoscopic surgeries currently represent the mainstay of surgical modalities. Pneumoperitoneum imposes significant intraoperative haemodynamic alterations, which are more pronounced in elderly patients and those with co-morbid conditions. Inadequate pain relief in the perioperative period may result in various physiological and psychological traumas. Aim: To investigate the effects of magnesium sulphate, dexmedetomidine, and lignocaine on the haemodynamic responses and postoperative analgesia in patients undergoing laparoscopic abdominal surgeries. Materials and Methods: This double-blinded, randomised clinical study was conducted in the general surgery operation theatre, Post-anaesthetic Care Unit (PACU), and the male and female surgery ward of RG Kar Medical College and Hospital, Kolkata, West Bengal, India from March 1, 2021, to March 1, 2022. The study involved 105 subjects assigned to Group-L, who received an injection of lignocaine as a loading dose of 1.5 mg/kg intravenously over 2-4 minutes before induction, followed by a continuous infusion of 2 mg/kg/hour throughout the surgery. Group-M received a loading dose of MgSO4 at 30 mg/ kg over 15 minutes before induction, followed by 15 mg/kg/hour throughout the surgery, and Group-D received a loading dose of dexmedetomidine at 1 mcg/kg over 10 minutes before induction, followed by a continuous infusion of 0.5 mcg/kg/min throughout the surgery. Data on Heart Rate (HR), Mean Arterial Pressure (MAP), and the total dose of rescue analgesic administered in the postoperative 24 hours were recorded and analysed using Analysis of Variance (ANOVA) and Tukey’s Honestly Significant Difference (HSD) test, as well as the Chi-square test where applicable. A p-value of less than 0.05 was considered statistically significant. Results: The groups were comparable in terms of demographic variables and baseline haemodynamic status. The average age in Group-D was 39.13±9.48 years, in Group-M was 37.30±8.14 years, and in Group-L was 36.5±7.2 years (p=0.26). Group-D had 60% males, Group-M had 57% males, and Group-L had 60% males. The mean Body Mass Index (BMI) of Group-D was 25.9±2.03 (kg/m2 ), Group-L (Lignocaine) was 24.7±2.7, and Group-M (Magnesium Sulphate) was 23.8±3.2. Dexmedetomidine was found to be superior in maintaining haemodynamic stability throughout the perioperative period (Preinduction HR: Group-D=79.43, Group-L=79.06, Group-M=82.09; Postinduction HR: Group-D=86.49, Group-M=65.91, GroupL=72.69). There was a significant decrease in postintubation MAP, most pronounced in the Magnesium Sulphate and Dexmedetomidine groups. Post-pneumoperitoneum, the surge in MAP was most effectively prevented by Dexmedetomidine. The lowest amount of rescue analgesic (injection Diclofenac in mg) was used in the Dexmedetomidine group (55.86±5.05), followed by the Lignocaine group (126.43±17.69). Patients in the Magnesium group required the highest amount of rescue analgesic (156.43±7.91). The number of patients receiving rescue analgesia was significantly higher in the Lignocaine and Magnesium Sulphate groups (Group-D: 6.5±3.14565, Group-L: 14.75±7.36, Group-M: 18.25±8.057). Conclusion: Dexmedetomidine was more effective in maintaining haemodynamic stability throughout the perioperative period and exhibited superior postoperative analgesic properties. Magnesium Sulphate and lignocaine were more effective in preventing postintubation surges.

Analgesic Efficacy of Dexmedetomidine as an Adjuvant to Ropivacaine in Supraclavicular Brachial Plexus Block for Upper Limb Surgeries: A Prospective Randomized Study

Background and Aims: The primary aim of this randomized controlled study was to evaluate the effect of the addition of dexmedetomidine to ropivacaine on the onset and duration of sensory and motor blockade and the duration of analgesia in patients undergoing upper limb surgeries under supraclavicular brachial plexus block. Materials and Methods: A total of 100 patients of age 18–55 years, planned for elective upper limb surgeries under supraclavicular brachial plexus block using a nerve stimulator, were randomly allocated into two groups. Group 1 (n = 50) received 30 mL 0.5% ropivacaine and 1 mL normal saline and Group 2 (n = 50) received 30 mL 0.5% ropivacaine and 1 μg/kg of dexmedetomidine. The onset and duration of sensory and motor block, duration of analgesia, and adverse events during the perioperative period were noted. Results: The onset of sensory and motor block in Group 1 (16. 26 ± 2.23 and 21.68 ± 2.90 min) was slower than those in Group 2 (9.12 ± 2.40 and 12.68 ± 2.62 min), (&lt;0.001). The duration of sensory and motor block in Group 1 was significantly shorter than those in Group 2 (P &lt; 0.001). The duration of analgesia in Group 1 (402.80 ± 28.21 min) was shorter than that in Group 2 (981.00 ± 92.26 min; P &lt; 0.001). There was no statistically significant difference between the two groups in the incidence of the side effects, except in the incidence of sedation which is significantly higher in Group 2, (P &lt; 0.001). Conclusion: Dexmedetomidine with ropivacaine for supraclavicular nerve block resulted in earlier onset and prolonged duration of the sensorimotor blockade and provided a longer pain-free postoperative period without significant hemodynamic alterations.

A Microsurgical Arteriovenous Malformation Model on Saphenous Vessels in the Rat.

Arteriovenous malformation (AVM) is an anomaly of blood vessel formation. Numerous models have been established to understand the nature of AVM. These models have limitations in terms of the diameter of the vessels used and the impact on the circulatory system. Our goal was to establish an AVM model that does not cause prompt and significant hemodynamic and cardiac alterations but is feasible for follow-up of the AVM's progression. Sixteen female rats were randomly divided into sham-operated and AVM groups. In the AVM group, the saphenous vein and artery were interconnected using microsurgical techniques. The animals were followed up for 12 weeks. Anastomosis patency and the structural and hemodynamic changes of the heart were monitored. The hearts and vessels were histologically analyzed. During the follow-up period, shunts remained unobstructed. Systolic, diastolic, mean arterial pressure, and heart rate values slightly and non-significantly decreased in the AVM group. Echocardiogram results indicated minor systolic function impact, with slight and insignificant changes in aortic pressure and blood velocity, and minimal left ventricular wall enlargement. The small-caliber saphenous AVM model does not cause acute hemodynamic changes. Moderate but progressive alterations and venous dilatation confirmed AVM-like features. The model seems to be suitable for studying further the progression, enlargement, or destabilization of AVM.

Irregular anatomical features can alter hemodynamics in Takayasu arteritis

ObjectiveTakayasu arteritis (TA) is a difficult disease to deal with because there are neither reliable clinical signs, laboratory biomarkers, nor a single noninvasive imaging technique that can be used for early diagnosis and disease activity monitoring. Knowledge of aortic hemodynamics in TA is lacking. This study aimed to fill this gap by assessing hemodynamics in patients with TA using image-based computational fluid dynamics (CFD) simulations. MethodsEleven patients with TA were included in the present study. Patient-specific geometries were reconstructed from either clinical aortic computed tomography angiography or magnetic resonance angiography studies and coupled with physiological boundary conditions for CFD simulations. Key anatomical and hemodynamic parameters were compared with a control group consisting of 18 age- and sex-matched adults without TA who had healthy aortas. ResultsCompared with controls, patients with TA had significantly higher aortic velocities (0.9 m/s [0.7, 1.1 m/s] vs 0.6 m/s [0.5, 0.7 m/s]; P = .002), maximum time-averaged wall shear stress (14.2 Pa [9.8, 20.9 Pa] vs 8.0 Pa [6.2, 10.3 Pa]; P = .004), and maximum pressure drops between the ascending and descending aorta (36.9 mm Hg [29.0, 49.3 mm Hg] vs 28.5 mm Hg [25.8, 31.5 mm Hg]; P = .004). These significant hemodynamic alterations in patients with TA might result from abnormal anatomical features including smaller arch diameter (20.0 mm [13.8, 23.3 mm] vs 25.2 mm [23.3, 26.8 mm]; P = .003), supra-aortic branch diameters (21.9 mm [18.5, 24.6 mm] vs 25.7 mm [24.3, 28.3 mm]; P = .003) and descending aorta diameter (14.7 mm [12.2, 16.8 mm] vs 22.5 mm [19.8, 24.0 mm]; P < .001). ConclusionsCFD analysis reveals hemodynamic changes in the aorta of patients with TA. The applicability of CFD technique coupled with standard imaging assessments in predicting disease progression of such patients will be explored in future studies. Future large cohort study with outcome correlation is also warranted. Clinical RelevanceBased on patient-specific computational fluid dynamics simulations, the present retrospective study revealed significant difference in aortic hemodynamics between the patients with and without Takayasu arteritis (TA). To the best of our knowledge, this study is the first to evaluate hemodynamic conditions within TA, demonstrating the potential of computational flow modeling in capturing abnormal hemodynamic forces, such as high wall shear stress, resulted from irregular morphological changes. In the future, assessing the hemodynamic parameters within patients with TA during the prestenotic period, together with longitudinal computational fluid dynamics studies may allow better monitoring and management of TA.

Biomechanical remodeling of the murine descending thoracic aorta during late-gestation pregnancy

With the rise in maternal mortality rates and the growing body of epidemiological evidence linking pregnancy history to maternal cardiovascular health, it is essential to comprehend the vascular remodeling that occurs during gestation. The maternal body undergoes significant hemodynamic alterations which are believed to induce structural remodeling of the cardiovascular system. Yet, the effects of pregnancy on vascular structure and function have not been fully elucidated. Such a knowledge gap has limited our understanding of the etiology of pregnancy-induced cardiovascular disease. Towards bridging this gap, we measured the biaxial mechanical response of the murine descending thoracic aorta during a normotensive late-gestation pregnancy. Non-invasive hemodynamic measurements confirmed a 50% increase in cardiac output in the pregnant group, with no changes in peripheral blood pressure. Pregnancy was associated with significant wall thickening ( ∼14%), an increase in luminal diameter ( ∼6%), and material softening in both circumferential and axial directions. This expansive remodeling of the tissue resulted in a reduction in tensile wall stress and intrinsic tissue stiffness. Collectively, our data indicate that an increase in the geometry of the vessel may occur to accommodate for the increase in cardiac output and blood flow that occurs in pregnancy. Similarly, wall thickening accompanied by increased luminal diameter, without a change in blood pressure may be a necessary mechanism to decrease the tensile wall stress, and avoid pathophysiological events following late gestation.

Study to compare the effect of Dexmedetomidine vs MgSo4 (50%) intrathecally as an adjuvant with bupivacaine (0.5%) for lower limb orthopedic surgery under subarachnoid block

Lower limb surgeries may be performed under local, regional (spinal or epidural) or general anesthesia, but neuraxial blockade is the preferred mode of anesthesia. Sub-arachnoid block or Spinal anaesthesia is the most common central block used in a surgical setting, which is being the most versatile and commonly used regional block. With increasing use of hyperbaric bupivacaine for sub arachnoid block, their limitations like prolongation of onset of sensory and motor blockage effect, short duration of action and early postoperative requirement of an analgesic agent, require an intrathecal adjuvant to these local anaesthetic agents for a complete satisfactory period of anaesthesia and patient satisfaction. The aim of this study was to compare and evaluate the effect of Dexmedetomidine with MgSO4 (50%) intrathecally as an adjuvant for the characteristics of sensory and motor blockage for lower limb orthopedic surgery under subarachnoid block along with bupivacaine (0.5%). : Participants were randomly divided into two groups of 40 participants each. Group D (n=40) received Bupivacaine + dexmedetomidine, Group M (n=40) received Bupivacaine + MgSO4. Under strict aseptic and antiseptic precaution subarachnoid block was performed. Mixture of drugs according to group assign was injected. Assessment of sensory and motor characteristics was done. Inj. Dexmedetomidine as an adjuvant in spinal block, seems to be superior to intra-thecal MgSO4 as it has faster onset, longer duration of action, prolonged analgesia in comparison with Magnesium Sulphate without significant hemodynamic alterations. Dexmedetomidine, as an adjuvant to Inj. Bupivacaine intra-thecally in sub-arachnoid block, has faster onset, longer duration of action, prolonged analgesia in comparison with Magnesium Sulphate.

Porcine Liver Transplantation Without Veno-venous Bypass As an Extended Criteria Donor Model.

Liver transplantation is regarded as the gold standard for the treatment of a variety of fatal hepatic diseases. However, unsolved issues of chronic graft failure, ongoing organ donor shortages, and the increased use of marginal grafts call for the improvement of current concepts, such as the implementation of organ machine perfusion. In order to evaluate new methods of graft reconditioning and modulation, translational models are required. With respect to anatomical and physiological similarities to humans and recent progress in the field of xenotransplantation, pigs have become the main large animal species used in transplantation models. After the initial introduction of a porcine orthotopic liver transplant model by Garnier et al. in 1965, several modifications have been published over the past 60 years. Due to specifies-specific anatomical traits, a veno-venous bypass during the anhepatic phase is regarded as a necessity to reduce intestinal congestion and ischemia resulting in hemodynamic instability and perioperative mortality. However, the implementation of a bypass increases the technical and logistical complexity of the procedure. Furthermore, associated complications such as air embolism, hemorrhage, and the need for a simultaneous splenectomy have been reported previously. In this protocol, we describe a model of porcine orthotopic liver transplantation without the use of a veno-venous bypass. The engraftment of donor livers after static cold storage of 20 h - simulating extended criteria donor conditions - demonstrates that this simplified approach can be performed without significant hemodynamic alterations or intraoperative mortality and with regular uptake of liver function (as defined by bile production and liver-specific CYP1A2 metabolism). The success of this approach is ensured by an optimized surgical technique and a sophisticated anesthesiologic volume and vasopressor management. This model should be of special interest for workgroups focusing on the immediate postoperative course, ischemia-reperfusion injury, associated immunological mechanisms, and the reconditioning of extended criteria donor organs.

Arterial Wave Reflection and Aortic Valve Stenosis: Diagnostic Challenges and Prognostic Significance.

IntroductionArterial wave reflection is an important component of the left ventricular afterload, affecting both pressure and flow to the aorta. The aim of the present study was to evaluate the impact of wave reflection on transvalvular pressure gradients (TPG), a key parameter for the evaluation of aortic valve stenosis (AS), as well as its prognostic significance in patients with AS undergoing a transcatheter aortic valve replacement (TAVR).Materials and MethodsThe study population consisted of 351 patients with AS (mean age 84 ± 6 years, 43% males) who underwent a complete hemodynamic evaluation before the TAVR. The baseline assessment included right and left heart catheterization, transthoracic echocardiography, and a thorough evaluation of the left ventricular afterload by means of wave separation analysis. The cohort was divided into quartiles according to the transit time of the backward pressure wave (BWTT). Primary endpoint was all-cause mortality at 1 year.ResultsEarly arrival of the backward pressure wave was related to lower cardiac output (Q1: 3.7 ± 0.9 lt/min vs Q4: 4.4 ± 1.0 lt/min, p < 0.001) and higher aortic systolic blood pressure (Q1: 132 ± 26 mmHg vs Q4: 117 ± 26 mmHg, p < 0.001). TPG was significantly related to the BWTT, patients in the arrival group exhibiting the lowest TPG (mean TPG, Q1: 37.6 ± 12.7 mmHg vs Q4: 44.8 ± 14.7 mmHg, p = 0.005) for the same aortic valve area (AVA) (Q1: 0.58 ± 0.35 cm2 vs 0.61 ± 0.22 cm2, p = 0.303). In multivariate analysis, BWTT remained an independent determinant of mean TPG (beta 0.3, p = 0.002). Moreover, the prevalence of low-flow, low-gradient AS with preserved ejection fraction was higher in patients with early arterial reflection arrival (Q1: 33.3% vs Q4: 14.9%, p = 0.033). Finally, patients with early arrival of the reflected wave (Q1) exhibited higher all-cause mortality at 1 year after the TAVR (unadjusted HR: 2.33, 95% CI: 1.17–4.65, p = 0.016).ConclusionEarly reflected wave arrival to the aortic root is associated with poor prognosis and significant aortic hemodynamic alterations in patients undergoing a TAVR for AS. This is related to a significant decrease in TPG for a given AVA, leading to a possible underestimation of the AS severity.

Age-Related Tortuosity of Carotid and Vertebral Arteries: Quantitative Evaluation With MR Angiography.

Background and PurposeThe vascular tortuosity (VT) of the internal carotid artery (ICA), and vertebral artery (VA) can impact blood flow and neuronal function. However, few studies involved quantitative investigation of VT based on magnetic resonance imaging (MRI). The main purpose of our study was to evaluate the age and gender effects on ICA and VA regarding the tortuosity and flow changes by applying automatic vessel segmentation, centerline tracking, and phase mapping on MR angiography.MethodsA total of 247 subjects (86 males and 161 females) without neurological diseases participated in this study. All subjects obtained T1-weighted MRI, 3D time-of-flight MR angiography, and 2D phase-contrast (PC) MRI scans. To generate quantitative tortuosity metrics from TOF images, the vessel segmentation and centerline tracking were implemented based on Otsu thresholding and fast marching algorithms, respectively. Blood flow and velocity were measured using PC MRI. Among the 247 subjects, 144 subjects (≤ 60 years, 49 males/95 females) were categorized as the young group; 103 subjects (>60 years, 37 males/66 females) were categorized as the old group.ResultsIndependent t-test showed that older subjects had higher tortuosity metrics, whereas lower blood flow and velocity than young subjects (p < 0.0025, Bonferroni-corrected). Cerebral blood flow calculated using the sum flux of four target arteries normalized by the brain mass also showed significantly lower values in older subjects (p < 0.001). The age was observed to be positively correlated with the VT metrics. Compared to the males, the females demonstrated higher geometric indices within VAs as well as faster age-related vascular profile changes. After adjusting age and gender as covariates, maximum blood velocity is negatively correlated with geometric measurements. No association was observed between blood flux and geometric measures.ConclusionsVascular auto-segmentation, centerline tracking, and phase mapping provide promising quantitative assessments of tortuosity and its effects on blood flow. The neck arteries demonstrate quantifiable and significant age-related morphological and hemodynamic alterations. Moreover, females showed more distinct vascular changes with age. Our work is built upon a comprehensive quantitative investigation of a large cohort of populations covering adult lifespan using MRI, the results can serve as reference ranges of each decade in the general population.

Cardioprotective effects of Talinum paniculatum (Jacq.) Gaertn. in doxorubicin-induced cardiotoxicity in hypertensive rats

Ethnopharmacological relevanceTalinum paniculatum (Jacq.) Gaertn. (Talinaceae) is a medicinal species that is widely distributed throughout Brazil. Popularly known as “major-gomes,” the species is used in folk medicine for the treatment of cardiovascular disorders. Aim of the studyTo evaluate the effect of an ethanolic extract of T. paniculatum (EETP) in rats with renovascular hypertension and heart failure and determine its chemical composition. Materials and methodsFirst, EETP was obtained, and its chemical profile was analyzed by LC-DAD-MS. The acute toxicity was evaluated in female Wistar rats. The model of renovascular hypertension was established in male Wistar rats by combining the Goldblatt 2K1C method and intraperitoneal doxorubicin administration for 6 weeks. The animals were then treated daily with EETP (30, 100, and 300 mg/kg) or metoprolol (25 mg/kg) by gavage for 28 days. The negative control group was treated with vehicle (filtered water). The sham group consisted of animals that were not subjected to 2K1C or cardiotoxicity and were treated with vehicle. Renal function was evaluated on days 1, 14, and 28. At the end of treatment, the electrocardiographic profile, blood pressure, and mesenteric vascular reactivity were investigated. Serum urea, creatinine, angiotensin converting enzyme, nitrotyrosine, malondialdehyde, nitrite, aldosterone, and sodium and potassium levels were measured. The heart, aorta artery, liver, and right kidney were collected, weighed, and processed for histopathological analysis. Cardiac chambers also underwent morphometric analysis. ResultsNo signs of toxicity were observed in female Wistar rats. Thirty-two compounds were annotated from EETP, including flavonoids, chlorogenic acids, and saponins. EETP treatment resulted in a significant cardiorenal-protective response, normalizing electrocardiographic and hemodynamic alterations, and preventing ventricle remodeling. These effects were associated with serum antioxidant activity and angiotensin-converting enzyme (ACE) inhibition. ConclusionThe present study demonstrated that EETP may exert cardioprotective effects through serum antioxidant activity and ACE inhibition, preventing alterations of hemodynamic and endothelial function, and reducing damage to cardiac structure. Thus, EETP, especially at the 100 and 300 mg/kg doses, may be useful for preventing doxorubicin-induced cardiotoxicity in hypertensive patients.

Fluid Flow Characteristics of Healthy and Calcified Aortic Valves Using Three-Dimensional Lagrangian Coherent Structures Analysis

Aortic valve calcification is an important cardiovascular disorder that deteriorates the accurate functioning of the valve leaflets. The increasing stiffness due to the calcification prevents the complete closure of the valve and therefore leads to significant hemodynamic alterations. Computational fluid dynamics (CFD) modeling enables the investigation of the entire flow domain by processing medical images from aortic valve patients. In this study, we computationally modeled and simulated a 3D aortic valve using patient-specific dimensions of the aortic root and aortic sinus. Leaflet stiffness is deteriorated in aortic valve disease due to calcification. In order to investigate the influence of leaflet calcification on flow dynamics, three different leaflet-stiffness values were considered for healthy, mildly calcified, and severely calcified leaflets. Time-dependent CFD results were used for applying the Lagrangian coherent structures (LCS) technique by performing finite-time Lyapunov exponent (FTLE) computations along with Lagrangian particle residence time (PRT) analysis to identify unique vortex structures at the front and backside of the leaflets. Obtained results indicated that the peak flow velocity at the valve orifice increased with the calcification rate. For the healthy aortic valve, a low-pressure field was observed at the leaflet tips. This low-pressure field gradually expanded through the entire aortic sinus as the calcification level increased. FTLE field plots of the healthy and calcified valves showed a variety of differences in terms of flow structures. When the number of fluid particles in the healthy valve model was taken as reference, 1.59 and 1.74 times more particles accumulated in the mildly and severely calcified valves, respectively, indicating that the calcified valves were not sufficiently opened to allow normal mass flow rates.

Automated detection of chronic kidney disease using image fusion and graph embedding techniques with ultrasound images

Chronic Kidney disease (CKD) is a progressive disease affecting more than twenty million individuals in the United States. Disease progression is often characterized by complications such as cardiovascular diseases, anemia, hyperlipidemia and metabolic bone diseases etc., Based on estimated GFR values, the disease is categorized in 5 stages which significantly influence patient outcome. Cardiovascular ultrasound (US) (echocardiography) imagery demonstrate significant hemodynamic alterations that are secondary to CKD in the form of volume/ pressure overload. As the CKD pathology directly impacts cardiovascular disease, the US imaging shows structural and hemodynamic adaptation. Hence, the development of a computer-aided diagnosis (CAD) model to predict CKD would be desirable, and can potentially improve treatment. Several prior studies have utilized kidney features for quantitative analysis. In this paper, acquisition of the four-chamber heart US image is employed to predict CKD stage. The method combines image and feature fusion techniques under a graph embedding framework to characterize heart chamber properties. Moreover, a support vector machine is incorporated to classify heart US images. The proposed method achieved 100 % accuracy for a two-class system, and 99.09 % accuracy for a multi-class categorization scenario. Hence, our proposed CAD tool is deployable in both clinic and hospital settings for computer-aided screening of CKD.

Comparison of ventilation with and without positive end expiratory pressure during anesthesia for laparoscopic surgeries

Respiratory dynamics are significantly altered during laparoscopic surgeries. Anesthesiologists should be well versed with the benefits as well as limitations of positive end expiratory pressure (PEEP) during laparoscopy. They can then judiciously use the same in different patient populations. In this study we have compared the effects of ventilation with and without PEEP of 10 cm on blood gases, airway pressures and hemodynamic parameters during laparoscopy. 60 patients, from American Society of Anesthesiologists (ASA) physical status I and II, in the age group of 18 to 60, posted for laparoscopic cholecystectomy were enrolled. They were randomized into two groups of 30 each. Group P received PEEP of 10 cm during laparoscopy and group C did not receive any PEEP. The vital parameters, arterial blood gases, and airway pressures were compared in both groups. The oxygenation, (PaO2/FiO2 ratio) was significantly higher in PEEP group (446. 4 ± 113.32 mm of Hg) as compared to the control group (404 ± 51.4 mm of Hg) after one hour of laparoscopy (P= 0.0037). The control group had higher arterial carbon dioxide tension (42.84 ± 2.38 mm of Hg) as compared to PEEP group (41.86 ± 2.33 mm of Hg), (P &amp;#60; 0.001). Both the findings suggest better ventilation perfusion matching in PEEP group. There was a no significant variation in mean arterial pressure and heart rate due to PEEP in our patient population. However the peak airway pressures were significantly higher in PEEP group. 10 cm of PEEP helped in better oxygenation with no significant hemodynamic alterations, in otherwise healthy patients undergoing laparoscopic cholecystectomy.

Pulmonary Complications of Cardiac Surgery.

Cardiothoracic surgery posits an arrangement of large, significant hemodynamic, and physiologic alterations upon the human body, which predisposes a patient to develop pathology. The care of these patients in the postoperative realm requires an astute physician with deep understanding of the cardiopulmonary system, who is able to address subtle developing problems promptly, before the patient suffers further sequelae. In this review, we describe the presentation and management of an assortment of important complications which occur in the pulmonary system. In addition, we aim to shed better light upon how the physiology of a patient responds to the condition of cardiothoracic surgery.

Proximal Aortic Compliance in Young Male Endurance Athletes: An MRI Study.

High-intensity endurance training can elicit profound cardiac adaptations; however, the current evidence as to its impact on the proximal aorta is limited. The purpose of this study was to investigate the morphological and functional characteristics of the proximal aorta in endurance athletes. Fifteen young male middle- and long-distance runners were compared with 19 age- and sex-matched sedentary control participants. CINE phase-contrast magnetic resonance imaging was used to measure blood flow velocities and cross-sectional areas of the ascending and proximal descending aorta. Aortic blood pressure was measured simultaneously during the phase-contrast magnetic resonance imaging scan using a generalized transfer function. Maximal oxygen uptake (V˙O2max) was measured in the athletes. Left ventricular morphology was assessed in a subgroup of participants (n = 16) with cardiac magnetic resonance imaging. The athlete group exhibited an average V˙O2max of 69.5 ± 3.1 mL·kg-1⋅min-1, which is above the 90th percentile of men with similar age according to the American College of Sports Medicine guideline. The athletes had significantly higher stroke volume and slower heart rate at rest and greater left ventricular end-diastolic volume and mass than the sedentary participants. Significantly larger cross-sectional areas and higher compliance of the ascending and proximal descending aorta were also found in the athletes, independently of body surface area. Moreover, higher compliance of the ascending aorta was associated with greater stroke volume (r = 0.382, P = 0.026) and slower heart rate (r = -0.442, P = 0.009) across all participants. The proximal aorta of young male endurance athletes undergoes morphological and functional adaptations that may be resulting from the significant hemodynamic alterations associated with their cardiac function.

Comparison of preemptive analgesia with bupivacaine versus bupivacaine-dexmedetomidine in femoral block for fracture femur

BACKGROUND: Patients with fracture femur experience very severe pain and anxiety. These patients require adequate analgesia to allow radiological, orthopedic, and other procedures. An ideal analgesic technique should provide pain relief without altering consciousness. Femoral nerve block (FNB) has been proved very effective in providing satisfactory analgesia in fracture femur patients. Dexmedetomidine has analgesic property when used as an adjuvant in regional anesthesia. MATERIALS AND METHODS: This prospective, double-blind randomized comparative study was conducted on sixty American Society of Anesthesiologists I and II patients scheduled for elective fracture femur surgeries. They were divided into equal groups of thirty patients. FNB was given 15 min prior to spinal anesthesia. Group B received injection 0.25% bupivacaine 20 ml + 0.5 ml normal saline in FNB, while Group D received injection 0.25% bupivacaine 20 ml + injection. Dexmedetomidine 1 μg/kg, making a total volume of 0.5 ml. Hemodynamic variables, Visual Analog Score (VAS) score, and duration of analgesia were recorded from baseline till the end of surgery and 2 h postoperatively. Statistical analysis was done using SPSS version 20.0 (IBM software product, USA). RESULTS: Duration of analgesia for Group B was 5.37 ± 0.56 h and for Group D was 6.63 ± 0.86 h. Duration of analgesia was prolonged in Group D. Fall in VAS was significantly higher in Group D after 10 min of femoral block compared to Group B. Although changes in heart rate, systolic blood pressure, and mean arterial pressure were statistically significant in both the groups, patients were hemodynamically stable. CONCLUSION: Addition of dexmedetomidine in a dose of 1 μg/kg to bupivacaine 0.25% in FNB effectively reduces pain associated with positioning for spinal anaesthesia and prolong the duration of analgesia and without significant hemodynamic alteration.

Metabolism plays a central role in the cortical spreading depression: Evidence from a mathematical model

The slow propagating waves of strong depolarization of neural cells characterizing cortical spreading depression, or depolarization, (SD) are known to break cerebral homeostasis and induce significant hemodynamic and electro-metabolic alterations. Mathematical models of cortical spreading depression found in the literature tend to focus on the changes occurring at the electrophysiological level rather than on the ensuing metabolic changes. In this paper, we propose a novel mathematical model which is able to simulate the coupled electrophysiology and metabolism dynamics of SD events, including the swelling of neurons and astrocytes and the concomitant shrinkage of extracellular space. The simulations show that the metabolic coupling leads to spontaneous repetitions of the SD events, which the electrophysiological model alone is not capable to produce. The model predictions, which corroborate experimental findings from the literature, show a strong disruption in metabolism accompanying each wave of spreading depression in the form of a sharp decrease of glucose and oxygen concentrations, with a simultaneous increase in lactate concentration which, in turn, delays the clearing of excess potassium in extracellular space. Our model suggests that the depletion of glucose and oxygen concentration is more pronounced in astrocyte than neuron, in line with the partitioning of the energetic cost of potassium clearing. The model suggests that the repeated SD events are electro-metabolic oscillations that cannot be explained by the electrophysiology alone. The model highlights the crucial role of astrocytes in cleaning the excess potassium flooding extracellular space during a spreading depression event: further, if the ratio of glial/neuron density increases, the frequency of cortical SD events decreases, and the peak potassium concentration in extracellular space is lower than with equal volume fractions.

P3466Cardiac output in end-stage liver disease increases with the severity of liver dysfunction

Abstract Background End-stage liver disease is associated with significant systemic and haemodynamic alterations that affect cardiac function. Cirrhotic cardiomyopathy remains an ill-defined entity among cardiologists. Understanding the complex interplay between liver dysfunction and cardiac function can lead to a better understanding of the compensatory mechanisms of the heart in liver failure. Purpose To investigate whether severity of liver disease affects baseline cardiac output in a large contemporary cohort of patients undergoing liver transplant work-up. Methods Consecutive patients that underwent pre-liver transplant (LT) workup between 2010–2017 were included. All patients underwent a resting echocardiogram. Cardiac output (CO) was prospectively recorded at baseline by pulsed-wave Doppler examination of the left ventricular outflow tract from the apical window and systemic vascular resistance (SVR) was calculated as 80 x (mean arterial pressure (MAP)/CO). Severity of liver disease was characterized by the model of end-stage liver disease (MELD) and Child-Pugh scores. Results 560 patients were included (mean age 57.5±7.7, 74.8% male). Mean MELD score was 19±7 and Child-Pugh Score was 9±3. There was an inverse linear relationship between the severity of liver disease by the MELD score and baseline SVR (rho 0.40, P&lt;0.001). As SVR reduced, there was also a significant rise in baseline CO with a strong inverse correlation between the two variables (rho 0.86, p&lt;0.001). There was a significant linear correlation between the severity of liver disease and baseline CO with both the scores (MELD Score rho 0.42, p&lt;0.001; Child Pugh rho 0.44, p&lt;0.001) (Figure). Baseline CO in LT Patients by Severity Conclusions Baseline CO increased with the severity of liver dysfunction due to a reduced afterload. A higher resting CO may lead to patients encroaching on their cardiac reserve at rest. This provides a pathophysiological insight suggesting a limited role for beta-blockers, particularly in patients with advanced liver cirrhosis.