Hemodynamics

The spectrum of left ventricular geometric adaptation to hypertension was investigated in 165 patients with untreated essential hypertension and 125 age- and gender-matched normal adults studied by two-dimensional and M-mode echocardiography. Among hypertensive patients, left ventricular mass index and relative wall thickness were normal in 52%, whereas 13% had increased relative wall thickness with normal ventricular mass (“concentric remodeling”), 27% had increased mass with normal relative wall thickness (eccentric hypertrophy) and only 8% had “typical” hypertensive concentric hypertrophy (increase in both variables).Systemic hemodynamics paralleled ventricular geometry, with the highest peripheral resistance in the groups with concentric remodeling and hypertrophy, whereas cardiac index was supernormal in those with eccentric hypertrophy and low normal in patients with concentric remodeling. The left ventricular shortaxis/long-axis ratio was positively related to stroke volume (r = 0.45, p < 0.001), with cavity shape most elliptic in patients with concentric remodeling and most spheric in those with eccentric hypertrophy. Normality of left ventricular mass in concentric remodeling appeared to reflect offsetting by volume “underload” of the effects of pressure overload, whereas eccentric hypertrophy was associated with concomitant pressure and volume overload.Thus, arterial hypertension is associated with a spectrum of cardiac geometric adaptation matched to systemic hemodynamics and ventricular load. Concentric left ventricular remodeling and eccentric hypertrophy are more common than the typical pattern of concentric hypertrophy in untreated hypertensive patients.

Objective To examine the effects of positive end-expiratory pressure (PEEP) on extravascular lung water (EVLW), lung tissue, and lung volume. Design and setting Experimental animal study at a university research facility. Subjects Fifteen adult sheep. Interventions All animals were studied before and after saline washout-induced lung injury while ventilated with sequentially increasing PEEP (0, 7, 14, or 21 cmH2O). Measurements and results Lung volume was determined by computed tomography and EVLW by the thermal dye dilution technique. Saline washout significantly increased lung tissue volume (21±3 to 37±5 ml/kg) and EVLW (9±2 to 36±9 ml/kg). While increasing levels of PEEP reduced EVLW (30±7, 24±8, and 18±4 ml/kg), lung tissue volume remained constant. Total lung volume significantly increased (50±8 ml/kg at PEEP 0 to 77±12 ml/kg at PEEP 21). Nonaerated lung volume significantly decreased and was closely correlated with the changes in EVLW (r=0.67). In addition, a highly significant correlation was found between PEEP-induced decrease in nonaerated lung volume and decrease in transpulmonary shunt (r=0.83). Conclusions The main findings are as follows: (a) PEEP effectively decreases EVLW. (b) The decrease in EVLW is closely correlated with the PEEP-induced decrease in nonaerated lung volume, making EVLW a valuable bedside parameter indicating alveolar recruitment, similar to measurements of transpulmonary shunt. (c) As excess tissue volume remained constant, however, EVLW may not be suitable to reflect overall severity of lung disease

Channichthyid icefishes of Antarctica are unique among adult vertebrates. All icefish species lack hemoglobin and red blood cells in their circulating blood. All icefishes examined to date also lack the intracellular oxygen-binding protein myoglobin (Mb) in their oxidative skeletal muscles. However, some icefish species do express Mb in their heart ventricles. It is unknown whether Mb in those species in which it is present represents an evolutionary relic or has functional significance. To address this problem, we compared mechanical performance of isolated, perfused hearts from two species of icefish in which Mb is either present (Chionodraco rastrospinosus) or is absent (Chaenocephalus aceratus). Hearts were challenged with increasing afterload (2.5-4.0 kPa) under conditions of defined basal flow (approximately 100 ml.min-1.kg-1), in both the presence and absence of 5 mM sodium nitrite, a Mb poison. Unlike hearts from C. aceratus, which were unable to maintain a constant cardiac ...

The objective of this study is to find a correlation between the abdominal aortic aneurysm (AAA) geometric parameters, wall stress shear (WSS), abdominal flow patterns, intraluminal thrombus (ILT), and AAA arterial wall rupture using computational fluid dynamics (CFD). Real AAA 3D models were created by three-dimensional (3D) reconstruction of in vivo acquired computed tomography (CT) images from 5 patients. Based on 3D AAA models, high quality volume meshes were created using an optimal tetrahedral aspect ratio for the whole domain. In order to quantify the WSS and the recirculation inside the AAA, a 3D CFD using finite elements analysis was used. The CFD computation was performed assuming that the arterial wall is rigid and the blood is considered a homogeneous Newtonian fluid with a density of 1050 kg/m3and a kinematic viscosity of4×10-3Pa·s. Parallelization procedures were used in order to increase the performance of the CFD calculations. A relation between AAA geometric paramet...

To examine the association of body mass index (BMI), triceps skinfold thickness (TST) and percentage body fat (%BF) from bioelectrical impedance analysis (BIA) with blood lipids, systolic blood pressure (SBP) and diastolic blood pressure (DBP) in children. Cross-sectional study was conducted on 1280 schoolchildren aged 8-11 years from the Cuenca province (Spain). Data collection was conducted under standardized conditions, taking several measurements of each variable to enhance accuracy. Analyses were performed using age-adjusted correlation coefficients, and multiple linear regression adjusted for age, BMI, TST and %BF. Correlations between %BF and apolipoprotein (apo) B, total cholesterol, low-density lipoprotein cholesterol (LDL-c), total cholesterol/HDL-c ratio and DBP were higher than those for BMI and TST. In contrast, the correlations between BMI, and apo A-I and SBP were higher than those for %BF and TST. The results were similar across the sexes. The correlations between each of the three measures of body fatness, and blood lipids and blood pressure were highest in children with greatest BMI and %BF. When analyses were adjusted for the three body fatness measures, %BF showed stronger associations than did BMI or TST with blood lipids and blood pressure, with the exception of apo A-I and SBP, which were more closely associated with BMI. %BF from BIA is more strongly associated than either BMI or TST with most of the blood lipid fractions in schoolchildren aged 8-11 years.

Introduction: Due to the nature of the space that endoscopic sinus surgery is performed in it, even a small
amount of bleeding has a negative effect on surgeon vision. The aim of this study was to compare the effects
of propofol and dexmedetomidine on controlled hypotension and bleeding during endoscopic sinus surgery.
Materials and Methods: In this randomized clinical trial, 100 patients candidate for endoscopic sinus
surgery entered the study. The patients were randomly divided into two groups. In the first group, Group D,
1 μg/kg dexmedetomidine was injected within 10 min as the initial dose and 0.4–0.8 μg/kg/h infusion was
continued. In Group P, 50–150 μg/kg/min Propofol was infused. Hemodynamic parameters were measured
from the onset of the study to 120 min after surgery, and the intraoperative bleeding was reported by surgeon.
Results: Mean score of bleeding was 1.14 ± 0.70 in Group D and 1.24 ± 0.74 in Group P (P = 0.490). Wilks’
group Lambda test showed a significant reduction in heart rate of both groups (F = 3.45, P = 0.002). Heart rate
in Group P was significantly lower than Group D (Greenhouse‑Geisser test, F = 2.70, P = 0.015). There was no
statistical difference in mean arterial pressure and O2 saturation. The average time of patients recovery was
32.52 ± 7.9 min in Group D and 29.90 ± 10.6 min in Group P (P = 0.166). Conclusion: Propofol could reduce
heart rate significantly more than dexmedetomidine. However, about reduction of bleeding and obtaining
an appropriate surgical field which were the main outcomes of the study, there was no significant difference
between groups.
Key words: Blood loss, controlled hypotension, dexmedetomidine, endoscopic sinus surgery, propofol

The velocity by which the disturbance travels through the medium is the wave velocity. Pulse wave velocity is one of the main parameters in hemodynamics. The study of wave propagation through the fluid-fill elastic tube is of great importance for the proper biophysical understanding of the nature of blood flow through of cardiovascular system. The effect of viscosity on the pulse wave velocity is generally ignored. In this paper we present the results of experimental measurements of pulse wave velocity (PWV) of compression and expansion waves in elastic tube. The solutions with different density and viscosity were used in the experiment. Biophysical model of the circulatory flow is designed to perform measurements. Experimental results show that the PWV of the expansion waves is higher than the compression waves during the same experimental conditions. It was found that the change in viscosity causes a change of PWV for both waves. We found a relationship between PWV, fluid density ...

The CardioWest total artificial heart (TAH) is a pneumatic device that is used as a bridge to heart transplantation and the only TAH available that totally replaces the failing ventricles. It has been utilized in selected centers in the U.S.A. with approval from the Food and Drug Administration. Strict criteria have been developed to select candidates to be bridged with the TAH. The patient must be a heart transplant candidate of age &amp;amp;amp;gt;18 and &amp;amp;amp;lt;59 years with a body surface area (BSA) &amp;amp;amp;gt; or = 1.7 m2, cardiac index (CI) &amp;amp;amp;lt;2.0 L/min/m2, and 2 inotropic agents or 1 plus an intraaortic balloon pump (IABP). A total of 24 heat transplant candidates (Group A) met the entry criteria and underwent placement of the TAH between January 1993 and July 1996. Group A consisted of 23 males; 16 patients had an IABP. The control group (Group B) consisted of 18 heart transplant candidates who met the TAH entry criteria but never received a TAH. Group B consisted of 15 males; 14 patients had an IABP. Preimplantation pulmonary vascular resistance (PVR) (Wood units), serum creatinine (mg/dl), and total bilirubin (mg/dl) were determined in both groups. The mean values for Groups A and B were, respectively, age: 47 and 47 years, BSA: 2.01 and 1.93 m2, CI: 1.5 and 1.8 L/min/m2, PVR: 2.88 and 2.47 Wood units, creatinine: 1.5 and 1.6 mg/dl, and bilirubin: 1.8 and 1.4 mg/dl. In Group A, 1 patient died on the TAH, 1 patient died after transplant, and 22 patients reached transplant and were discharged home for a survival rate of 91.7%. In Group B, 10 patients died while waiting for a heart transplant. Of the 8 patients transplanted, 7 survived and were discharged home for a survival rate of 38.9% (p = 0.0003). In summary the CardioWest TAH provided an excellent and successful method of bridging patients to heart transplantation with a reasonable risk.