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We studied the changes in acceleration time/right ventricular ejection time ratio (AT/RVET; indicative of changes in pulmonary artery pressure) calculated from Doppler ultrasound examinations performed before and 1, 6, and 12 h after the first and second doses of surfactant following the administration of each of three different surfactants during the acute phase of the respiratory distress syndrome. Maximum fractional inspired oxygen concentration (F(I,O2)) and peak inspiratory pressure (PIP) were recorded during each 4 h period from birth for the first 24 h and subsequently every 24 h until 72 h. Eighty-three infants were studied. Fifty patients weighing > 1 kg received Exosurf (n = 29) or ALEC (n = 21) and 33 weighing 1 kg who received Exosurf and those who received ALEC (a synthetic surfactant). Similarly, there was no difference between those infants 1 kg who received Exosurf compared with those who received ALEC. The rise in AT/RVET found in this study after administration of ALEC, Exosurf, or Survanta suggests that similar and rapid falls in pulmonary artery pressure occur after all three surfactant administrations, despite the difference in clinical response demonstrated between Exosurf and Survanta.

Objectives. We sought to use intracardiac echocardiography (ICE) to identify the anatomic origin of focal right atrial tachycardias and to define their relation with the crista terminalis (CT). Background. Previous studies using ICE during mapping of atrial flutter and inappropriate sinus tachycardia have demonstrated an important relation between endocardial anatomy and electrophysiologic events. Recent studies have suggested that right atrial tachycardias may also have a characteristic anatomic distribution. Methods. Twenty-three consecutive patients with 27 right atrial tachycardias were included in the study. ICE was used to facilitate activation mapping in relation to endocardial structures. A 20-pole catheter was positioned along the CT under ICE guidance. ICE was also used to assist in guiding detailed mapping with the ablation catheter in the right atrium. Results. Of 27 focal right atrial tachycardias, 18 (67%, 95% confidence interval [CI] 46% to 83%) were on the CT (2 high medial, 8 high lateral, 6 mid and 2 low). ICE identified the location of the tip of the ablation catheter in immediate relation to the CT in all 18 cases. The 20-pole mapping catheter together with echocardiographic visualization of the CT provided a guide to the site of tachycardia origin along this structure. Radiofrequency ablation was successful in 26 (96%) of 27 (95% CI 81% to 100%) right atrial tachycardias. Conclusions. This study demonstrates that approximately two thirds of focal right atrial tachycardias occurring in the absence of structural heart disease will arise along the CT. Recognition of this common distribution may potentially facilitate mapping and ablation of these tachycardias.

Many applications of electrokinetic remediation have focused on the removal of heavy metals. However, the application of electrokinetic technology in salt removal from contaminated soils and groundwater has not been extensively explored. Given the current global challenge and the impact of soil and groundwater salinity, it is tempting to suggest that the research community should apply this technology to generate in-depth knowledge for determining the feasibility and efficiency of electrokinetic remediation in salt removal, particularly in addressing seawater intrusion in coastal aquifers, which is creating growing challenges in the freshwater supply, mainly in coastal and arid regions, in view of growing populations, economic and industrial growth, and climate change. This Review shows that there is a need to begin formulating a knowledge base about categories of materials, efficiencies, and limitations. Furthermore, the viability of this technology in the real field suggests a need to gain more insight into electrokinetic applications in this area. The versatility of electrokinetic remediation in different settings is demonstrated in this Review, as is its capability to address diverse remediation challenges. The available literature is critically assessed; novel and improved electrokinetic remediation and the important trends in this field are outlined. The Review aims to summarize the evolution and current status of electrokinetic remediation research with a view of starting a debate around the possibility of applying it as a pretreatment mechanism to control seawater intrusion.

A natural coordinate system is introduced in this work to handle the flow of a multiphase fluid in domains possessing curved boundaries. A multiple transformation that is capable of mapping a (single) physical domain onto a (single) computational domain is derived. This work furnishes the necessary theoretical foundation for the concept of natural coordinate systems for multiphase flows.

Fourteen patients with typical atrial flutter underwent pacing from the low lateral right atrium and the proximal coronary sinus in normal sinus rhythm before and after catheter ablation. During low lateral right atrial pacing, a positive change in P-wave morphology in the inferior leads was noted in every patient (n = 12) in whom bidirectional block was achieved; no recurrence was noted in any of these patients.

Introduction: Postural orthostatic tachycardia syndrome (POTS) is a rare disease characterized by syncope, sinus tachycardia, and orthostasis due to autonomic dysfunction. Methods and Results: Two women aged 26 and 24 years with severe POTS became pregnant. Both women experienced hyperemesis gravidarum with subsequent marked improvement in their POTS symptoms until 6 months gestation, when their syncope and sinus tachycardia caused clinical decompensation. Both patients delivered healthy babies at 37 weeks by elective cesarian section. Conclusion: In long-term follow-up, both women reported improvement in their prepartum symptoms. We describe the first report, to our knowledge, of two successful pregnancy outcomes in severe POTS, including the first report of midodrine use in pregnant women.

Predictors of defibrillation threshold (DFT) at implantation remain poorly defined. It was hypothesized that a greater wall motion score index (WMSI) at rest on echocardiography and an ischemic or biphasic response on dobutamine stress echocardiography (DSE) would predict a greater DFT. Consecutive patients who underwent implantable cardiac-defibrillator implantation underwent echocardiography and DSE. DFT at implantation was assessed using the step-down method. Thirteen men aged 68 +/- 10 years with left ventricular ejection fractions of 28 +/- 10% participated in the study. DFTs ranged from 5 to 25 J (mean 14 +/- 8). A WMSI at rest ofor = 2.5 had a 71% positive predictive value and an 83% negative predictive value for a DFTor = 15 J. An ischemic or biphasic response during DSE did not predict a greater DFT at implantation.

Background: The incidence of adult patients with falls seeking medical assistance in the Salt Lake City area, Utah, is 28,000 per million adult inhabitants. Objective: We sought to evaluate the prevalence of cardiovascular risk assessment and cardiovascular abnormalities in patients presenting with nonaccidental falls at the University of Utah hospital and its affiliated clinics. Methods: We conducted a search of all patients in the University of Utah patient database as well as 9 affiliated primary care and family practice clinics in Utah who were evaluated for a “fall” during October 2009. We analyzed the records of 338 patients who had a fall within the previous 3 months. Nonaccidental falls were defined as falls unrelated to a contact incident or “slip or trip.” Results: Nonaccidental falls occurred in 81 (24%) patients, 39 of these being ≥65 years old. Cardiovascular risk assessment and specifically orthostatic testing were evaluated in 40% and 3% of the patients, respectively. In patients ≥65 years old, the prevalence of cardiovascular risk assessment, orthostatic testing, and carotid sinus massage were equally low at 56%, 5%, and 0%, respectively. Cardiovascular abnormalities were present in 17 (21%) patients, with 9 of them being referred for cardiac evaluation. Conclusion: Our results highlight the inconsistent assessment of potential cardiovascular risk factors in patients with nonaccidental falls, supporting the adoption of a standardized approach in these patients.

It has previously been shown that trichloroethylene (TRI) and 1,1,2-trichloro-1,2,2-tri-fluoroethane (FC 113) interfere with the transport of bile acids by isolated human and rat hepatocytes in a dose-dependent and reversible manner. This finding may explain the rise in serum bile acids (SBA) following exposure to these chemicals. However, the effect of these compounds on the transport of bile acids across the cellular membrane in the absence of confounding variables, such as interference by intracellular metabolism, binding to cytosolic proteins and intracellular conjugation, has not been investigated. Accordingly, in vitro effects of TRI and FC 113 on uptake of [(3)H]taurocholate (TC) into purified basolateral (blLPM) and canalicular (cLPM) rat liver plasma membrane vesicles were examined by a rapid filtration technique. Both TRI and FC 113 caused a dose-dependent inhibition of TC uptake into blLPM vesicles at an approximate concentration of 3 mm and 72 mum, respectively. Initial rates of TC uptake in the presence of TRI and FC 113 were significantly inhibited by 69 and 61%, respectively (P0.05). In contrast, these chemicals had no effect on TC uptake into cLPM vesicles. This confirms studies in intact cells where these solvents were found to inhibit the uptake of bile acids by hepatocytes rather than interfere with the process of efflux. In conclusion, and consistent with the previous findings, the data suggest that the mechanism of TRI and FC 113-induced elevation of SBA may, in part, be due to selective inhibition of bile acid transport by the parent compounds at the basolateral domain of the hepatocyte plasma membrane.

ObjectivesWe attempted to determine the correlation between the presence of postextrasystolic changes in the STU segment and a history of sustained ventricular arrhythmias.BackgroundPostextrasystolic U wave augmentation (a marked increment in U wave amplitude after premature ventricular complexes [PVCs]) is an adverse prognostic sign in the “pause-dependent long QT syndrome.” However, the prevalence of post-extrasystolic changes in patients without the long QT syndrome is unknown.MethodsWe compared the configuration of the STU segment of the postextrasystolic beat (the sinus beat after a PVC) with the STU configuration during sinus rhythm in three patient groups: 1) 41 patients with spontaneous ventricular tachycardia/ fibrillation (VT/VF) (VT/VF group), 2) 63 patients with heart disease and high grade ventricular arrhythmias (control group), and 3) 29 patients with high grade ventricular arrhythmias but no heart disease (reference group).ResultsPostextrasystolic T wave changes did not correlate with a history of ventricular tachyarrhythmias. However, postextrasys-tolic U wave changes were more common among the patients with VT/VF than among control subjects (39% vs. 8.7%, p < 0.001). By logistic multiple regression analysis, a low left ventricular ejection fraction (p < 0.001) and postextrasystolic U wave changes (p < 0.005) were independent predictors of ventricular tachyarrhythmias.ConclusionsPostextrasystolic T wave changes are common and lack predictive value. Postextrasystolic U wave changes may be a specific marker of a tendency to the development of spontaneous ventricular arrhythmias. Prospective studies should be performed to confirm this association.

The squeezing flow of polar fluids is analyzed using the method of successive approximations in an attempt to derive second approximations to the velocity field and the spin field. An expression for the resistance to motion is also derived and comparisons are made with the case of squeezing flow of Newtonian fluids.

The effects of exposure to solvents on serum bile acids were investigated by comparing a group of apprentice vehicle spray painters (exposed group) with one of apprentice electricians. Apprentice spray painters from the study were subdivided into high- and low-solvent-exposure groups. Concentrations of individual serum bile acids (SBA) were measured and compared with conventional liver function tests (LFTs). Total, free, glycine- and taurine-conjugated SBA were consistently found to be present at higher levels in the spray painters than in the electricians, even at the beginning of the apprenticeship. Total SBA tended to increase in spray painters with increasing years of exposure during the apprenticeship, but this was significant at only one time point. No rises were observed over the sampling period in electricians. The mean values of individual and total SBA concentrations were all found to be higher in the high-exposure group than in the low-exposure group, with some differences reaching statistical significance. None of the routine liver biochemistry parameters was different between spray painters and electricians. gamma-Glutamyl transferase (GGT) was the only enzyme found to be significantly different between the high- and low-exposure groups, but all values were within the normal range. This study suggests that occupational exposure even to low levels of solvent mixtures results in increases in SBA. The increased SBA may be indicative of a subclinical liver dysfunction. Alternatively, they may reflect solvent exposure only, with the raised levels having no pathologic implication or consequence.

Mutations in the Na-K-2Cl cotransporter (NKCC2), a mediator of renal salt reabsorption, cause Bartter's syndrome, featuring salt wasting, hypokalaemic alkalosis, hypercalciuria and low blood pressure. NKCC2 mutations can be excluded in some Bartter's kindreds, prompting examination of regulators of cotransporter activity. One regulator is believed to be ROMK, an ATP-sensitive K+ channel that 'recycles' reabsorbed K+ back to the tubule lumen. Examination of the ROMK gene reveals mutations that co-segregate with the disease and disrupt ROMK function in four Bartter's kindreds. Our findings establish the genetic heterogeneity of Bartter's syndrome, and demonstrate the physiologic role of ROMK in vivo.

Convergence history and its dependence on the direction of discretization are investigated when a boundary value problem is given in a curvilinear domain and the finite differences procedure is used. An attempt is made to determine the best relaxation direction when a near-optimal relaxation parameter is employed. Results emphasize the critical role of the grid aspect ratio.

A set of partial differential equations describing the motion of a dusty fluid in porous media are developed. The governing equations are derived using intrinsic volume averaging and are based on Saffman's dusty gas model. The effect of the porous microstructure on the flowing mixture is analyzed via the concept of representative unit cell (RUC), and distinction is made between flow in consolidated and granular porous media.

Exposure to an atmosphere of 30% carbon dioxide caused increased levels of phenylalanine ammonia-lyase (PAL) activity in avocado cell suspension cultures. The carbon dioxide treatment also enhanced chalcone synthase activity by 30% and resulted in a 1.5-2 fold greater accumulation of epicatechin than in untreated cells. It was concluded that the level of epicatechin in avocado suspension cells can be increased by carbon dioxide, and this increase appears to be regulated by PAL and CHS activation.

Radiofrequency catheter ablation has been increasingly used in the treatment of ventricular tachycardia (VT). The success rates have been high in the management of patients with bundle branch reentry tachycardia and idiopathic ventricular tachycardia. Ablation of the right bundle branch provides a permanent cure for patients with bundle branch reentrant tachycardia. Similarly, using pace mapping and endocardial activation mapping, the tachycardia focus can be eliminated in more than 90% of patients with idiopathic VT. In this article, we review the clinical characteristics, electrophysiologic features and management of these arrhythmias, with an emphasis on the role of radiofrequency catheter ablation.

The needs for water supply in the western coastal zone of Kavala (N. Greece) have been rapidly increased during the last decades because of the high tourist and agricultural development. This resulted to a number of wells that drilled along the coastline. During summer period, when human and irrigation consumptions are maximized, phenomena of groundwater salinization are observed. Although restrictions to new drillings have been taken, salinization in some aquatic systems of the area tends to become a major environmental and economical issue. The only available information till now was a timeseries of groundwater electrical conductivity measurements, in some of the wells of the area. This information is useful but not adequate for the study of the salt intrusion mechanism. Geophysical investigation was carried out and electrical resistivity tomography (ERT) was chosen as the most appropriate technique for the case. The geophysical survey was set in a site between the coastline and an existing borehole. The 2D ERT profiles gave a clear image of geoelectrical heterogeneities, associated with seawater intrusion in the coastal aquifers, contributing to future measures towards a rational management of ground water resources in the area.

The implementation of the classical form of the von Mises transformation in the study of fluid flow in two-dimensional curvilinear domains gives rise to an infinite Jacobian of transformation when viscous fluid flow is considered and when the streamlines of the flow become vertical at any point in the flow domain. In this work, it will be shown that in special cases the infinite nature of the Jacobian can be eliminated when the streamlines are vertical by utilizing the polar form of the transformation.

This paper is concerned with the treatment of fluid‐structure interaction problems. The paper is divided in a number of sections. The first is an introduction to the historical background which lead to the numerical approach being used today. In the second the main factors affecting the numerical treatment of fluid‐structure interaction problems are identified. The next eight sections discuss each of these factors separately. Conclusions are drawn in section eleven.

This paper, which is concerned with fluid‐structure interaction analysis, is a sequel to our earlier paper which gave an introduction to the numerical treatment of such systems. The paper is divided into five main sections. In the first two, a state‐of‐the‐art review on near‐field and far‐field fluid structure interaction is presented. In attempting to highlight where current research should be directed, only the most widely used computer codes are reviewed in the third section. Conclusions are presented in the fourth section.

Patients with vasovagal syncope (VVS) and positive tilt table test (TTT) were not found to benefit from pacing in the ISSUE-3 trial despite the presence of spontaneous asystole during monitoring. “Hypotensive susceptibility” unmasked by TTT was reported as a possible explanation. It is unclear

Atrial fibrillation (AF) is characterized by multiple rapid and irregular atrial depolarization, leading to rapid ventricular responses exceeding 100 beats per minute (bpm). We hypothesized that rapid and irregular pacing reduced intravascular shear stress (ISS) with implication to modulating endothelial responses. To simulate AF, we paced the left atrial appendage of New Zealand White rabbits (n = 4) at rapid and irregular intervals. Surface electrical cardiograms were recorded for atrial and ventricular rhythm, and intravascular convective heat transfer was measured by microthermal sensors, from which ISS was inferred. Rapid and irregular pacing decreased arterial systolic and diastolic pressures (baseline, 99/75 mmHg; rapid regular pacing, 92/73; rapid irregular pacing, 90/68; p < 0.001, n = 4), temporal gradients ( $${\partial\tau/\partial t}$$ from 1,275 ± 80 to 1,056 ± 180 dyne/cm2 s), and reduced ISS (from baseline at 32.0 ± 2.4 to 22.7 ± 3.5 dyne/cm2). Computational fluid dynamics code demonstrated that experimentally inferred ISS provided a close approximation to the computed wall shear stress at a given catheter to vessel diameter ratio, shear stress range, and catheter position. In an in vitro flow system in which time-averaged shear stress was maintained at $${{\tau_{\rm avg}} = 23 \pm 4\, {\rm dyn}\, {\rm cm}^{-2} {\rm s}^{-1}}$$ , we further demonstrated that rapid pulse rates at 150 bpm down-regulated endothelial nitric oxide, promoted superoxide (O 2 .− ) production, and increased monocyte binding to endothelial cells. These findings suggest that rapid pacing reduces ISS and $${\partial\tau/\partial t}$$ , and rapid pulse rates modulate endothelial responses.

Premature ventricular complexes have been recently recognized as a reversible cause of cardiomyopathy. The purpose of this study was to determine if premature complexes independent of "dyssynchrony" resulted in increased left ventricular (LV) dimensions and decreased LV function.Ten mongrel dogs underwent the implantation of a pacemaker and were randomized to a control group (n = 5) or a paced group (n = 5). In the paced group, the pacemaker was connected to two endocardial atrial leads, one inserted into the atrial port and the other one into the ventricular port with an atrioventricular delay adjusted to ensure the presence of coupled pacing simulating atrial bigeminy with conducted beats in the absence of aberrancy. Echocardiographic parameters of LV size (LV end-diastolic diameter [LV-EDD], LV end-systolic diameter [LV-ESD]), and LV ejection fraction (LVEF) were measured at baseline and after 4 weeks of monitoring (control group) or pacing (paced group).In the control group, LV size decreased with no significant changes in LVEF: 55% at baseline versus 70% at 4 weeks (P = 0.23). In the paced group, LV-EDD decreased with no significant change in LV-ESD. Unlike the control group, LVEF decreased significantly from 69 ± 9% at baseline to 32 ± 22% after 4 weeks of pacing (P = 0.05).We have shown that 4 weeks of coupled pacing simulating atrial bigeminy significantly reduced LV function. Our findings suggest that premature complexes independent of ventricular dyssynchrony might lead to the development of cardiomyopathy.

Nonaccidental falls are often the result of a combination of factors including cardiovascular disorders such as orthostatic hypotension and unspecified cardiac arrhythmias. The objective of this study was to determine if there is an association between atrial fibrillation (AF) and nonaccidental falls.We reviewed the records of 442 consecutive patients65 years old who presented to the Emergency Department at the University of Utah Medical Center with a complaint of fall.Two-hundred eleven patients presented with nonaccidental fall, 231 patients with accidental fall. Patients with nonaccidental fall were more likely to be older, have a history of hypertension and neurological disorders, and taking five or more medications when compared to patients with accidental fall. Despite a similar prevalence of sinus rhythm at presentation, the prevalence of a history of AF was significantly higher in patients with nonaccidental fall compared to patients with accidental fall (26% vs 15%; P = 0.003). After adjusting for clinically and statistically significant predictors with a multivariate logistic regression analysis, AF, neurological disorders, and age ≤81 years were independent predictors of nonaccidental fall. In patients ≤81 years old (median age), the risk of nonaccidental falls was 2.5 times greater in patients with a history of AF when compared to those without a history of AF (odds ratio = 2.53 [confidence interval 95% 1.3-5], P = 0.007).AF is an independent risk factor for nonaccidental falls. Our results emphasize the need to screen for AF in patients presenting with nonaccidental fall.

The effects of radio-frequency ablation (RFA) on blood pressure (BP) regulation in patients with atrial fibrillation (AF) and hypertension remain unknown. We hypothesized that patients with successful ablation had a lower BP and/or lesser utilization of antihypertensive drug therapy during follow-up when compared to patients with failed ablation. This was a retrospective evaluation of patients with AF and hypertension treated with ablation at the University of Utah between July 2006 and June 2010. BP and use of antihypertensive medications were assessed at baseline and 1 year follow-up. A total of 167 patients were identified. Eight patients were excluded due to the need for AAD therapy beyond the blanking period thus leaving 80 patients in the success group and 79 patients in the failure group. The mean BP and HR at baseline were not significant between the groups. In the success group, the mean systolic BP decreased from a baseline value of 129 ± 17 to 125 ± 14 mmHg at 1 year (p = 0.075). In contrast, in the failure group, the mean systolic BP increased from a baseline value of 124 ± 16 to 127 ± 14 mmHg at 1 year (p = 0.176). Between-group comparison revealed a p value of 0.026. Minimal changes in diastolic BP were noted in both groups. No significant changes in antihypertensive therapy were noted. We have shown that successful catheter ablation in patients with AF and hypertension is associated with a decrease in systolic BP when compared to an increase in patients with failed ablation. Our findings suggest that restoring sinus rhythm could have an antihypertensive effect in patients with AF and hypertension.

Despite the availability of guidelines, the evaluation of patients with faint continues to be inconsistent. The purpose of this study was to test the hypothesis that utilization of a new standardized-care pathway (Faint-Algorithm) reduces hospital admissions and improves diagnostic yield when compared to the conventional approach in the evaluation of patients with faint.We reviewed the data of 154 consecutive patients presenting with faint to the Faint and Fall Clinic at the University of Utah (standardized group) and 100 patients previously evaluated for faint using the conventional approach (conventional group).Using a standardized approach, only 4% of patients were admitted when compared to 20% in the conventional group (P0.001). The rate of diagnosis at initial evaluation was similar between the groups; however, at 45 days, it was greater in the standardized group when compared to the conventional group (57% vs 45% in the total population, P = 0.09; 57% vs 39% in the outpatient subgroups, P = 0.02). The number of tests or consultations associated with additional charges was significantly lower in the standardized group when compared to the conventional group (1.9 ± 1.0 vs 2.6 ± 1.2, P = 0.001).The use of a standardized approach in the evaluation of patients with faint decreased the number of hospital admissions and increased the rate of diagnosis at 45 days. This was achieved with less utilization of costly tests and consultations.

Effects of Rhythm Control on Blood Pressure. Introduction: The long-term effects of atrial fibrillation (AF) on blood pressure (BP) in patients with hypertension (HTN) remain unclear. We hypothesized that restoration of normal sinus rhythm (NSR) results in a decrease in BP despite the expected increase in cardiac output. Methods and Results: Twenty-four-hour BP measurements were obtained during AF, and on Day 1 and Day 30 post-successful cardioversion in 18 patients with AF and HTN (cardioversion group), and another 22 patients with AF and HTN with no immediate plans for cardioversion (control group). Except for the duration of AF, the clinical characteristics and use of medications were similar between the groups. In the cardioversion group, a significant decrease in diastolic blood pressure (DBP) and mean blood pressure (MBP) were noted on Day 1 post-cardioversion with no significant change in systolic blood pressure (SBP): 117/74/88 ± 13/9/9 mmHg during AF and 116/70/85 ± 13/9/10 mmHg during Day 1 post-cardioversion (P = 0.68

The leading models of single-phase fluid flow through porous media are reviewed and the boundary conditions associated with these models are discussed. Entry conditions to a porous channel that are compatible with the different flow models when the flow is fully developed are derived. Comparison of these entry profiles is made for different flow parameters with the corresponding entry condition when the flow is governed by the Navier–Stokes equations.

Aims Syncope is a major health care problem that accounts for many emergency department (ED) and hospital admissions. This study was conducted to investigate the short-term risk of serious events in patients presenting to the ED with syncope and to compare guideline-based admission criteria with those adopted in clinical practice. Methods and results A single-centre retrospective analysis was performed on ED visits between January and June 2009. We used the ICD-9 code 780.2 for syncope as the primary diagnosis. The prevalence of serious events within 7 days of the index presentation was evaluated. In addition, admissions and discharges were classified as being appropriate or inappropriate based on standardized guideline-based criteria integrated in a new Faint-Algorithm developed at the University of Utah. Two hundred and fifty-four ED visits met the inclusion criteria. One hundred and thirty-six patients were discharged home and the remaining 118 were admitted. The prevalence of serious events in the discharged and admission groups were 5 and 10, respectively, ( P = NS). According to the Faint-Algorithm, the number of inappropriate discharges and admissions were 8 out of 136 and 69 out of 118, respectively. Using the Faint-Algorithm, only 57 patients instead of 118 patients should have been admitted resulting in a 52% reduction in admission rate. Furthermore, in the remaining 197 patients who should have been discharged, the prevalence of serious events was not significantly different than that observed in the 136 patients who were actually discharged (3% vs. 4%). Conclusion There are significant numbers of inappropriate discharges and admissions in patients presenting with syncope. The standardized guideline-based criteria integrated in the new Faint-Algorithm provide promise but require further prospective evaluation.

The temporal relationship between trichloroethylene (TRI) and individual serum bile acids (SBA) has been investigated to gain insight into the mechanism of solvent-induced increases in SBA. Male Sprague-Dawley rats were treated with 1 mmol/kg TRI in corn oil, while control rats received only corn oil. Blood samples were collected from the abdominal aorta at 2, 4, 8, and 16 hr after dosing. Individual SBA were determined by high-performance liquid chromatography (HPLC). Liver and blood concentrations of TRI and one of its metabolites, trichloroethanol (TCEOH), were determined by gas chromatography. SBA levels reached their peak at 4 hr and returned to control levels by 16 hr. There was a relationship between SBA levels and TRI concentrations, which were also at their peak 4 hr after dosing. By 16 hr the levels were undetectable. However, peak blood concentrations of TCEOH were reached 8 hr after dosing, and remained high at 16 hr. Cholic acid and taurocholic acid showed the highest levels of bile acids. Some other bile acids were also elevated, including deoxycholic acid, taurodeoxycholic acid, ursodeoxycholic acid, chenodeoxycholic acid, and taurochenodeoxycholic acid. Determination of total bile acids in serum using an enzymatic/colorimetric method showed a similar pattern of response to that obtained with the HPLC analysis. The data are consistent with TRI having a rapid and specific effect on SBA levels by a mechanism other than liver cell damage.

The differential equations governing the flow of an incompressible dusty fluid through porous media, based on the Darcy-Lapwood-Brinkman-Saffman (DLB-S) models derived in Part I are solved numerically to illustrate the deterministic nature of the models and to study the effect of introducing a small concentration of dust, by volume, on the fluid-phase characteristics. The fluid is assumed to flow through a finite porous channel into a two-dimensional line sink. Various models are treated to provide a comparison between the two-way and the different one-way interaction processes possible between the phases present. Analyses indicate that the way in which the Darcy resistance is defined is a major distinguishing factor between the models.

Mathematical models based on the differential equations approach are developed to describe the motion of an incompressible dusty fluid in porous media. The macroscopic governing equations are derived through the volume-averaging technique and take into account the cases of one-way and two-way interaction between the phases present. The models, based on Saffman's dusty gas model, are then subclassified to account for the different types of flow through porous media.

D the frequent use of amiodarone, questions about the effect of this drug on the defibrillation threshold (DFT) have not been fully answered. Previous clinical investigations have shown this drug to increase the DFT when using monophasic shocks,1–3 whereas other studies showed no effect.4 Implantable cardioverter-defibrillators (ICDs) now use biphasic waveforms because they are more effective in terminating ventricular fibrillation. Several recent uncontrolled studies comparing biphasic DFTs in populations of patients on and off amiodarone suggested no difference in the DFT between the 2 groups.5,6 Pelosi et al7 recently reported an increase in the biphasic DFT with chronic amiodarone use, measured on average 2 to 3 months after drug initiation, but provided no data regarding acute effects of the drug. We examined the immediate effects of in-hospital oral amiodarone loading on the biphasic DFT. • • • This study compared the DFTs of 18 patients (16 men and 2 women, mean age 63 6 10 years) at the time of initial implantation and after receiving an in-hospital load of oral amiodarone for clinically indicated reasons. The initial indication for ICD implantation was ventricular tachycardia in 17 patients and resuscitated cardiac death in 1 patient. Ten patients had underlying coronary artery disease, and 8 had dilated cardiomyopathy. Left ventricular function was severely depressed (,30%) in 15 patients; in 3 other patients it was moderately depressed (30% to 39%), mildly depressed (40% to 49%), and preserved (.50%). The implanted ICD models included the 7223Cx (n 5 7) and 7227Cx (n 5 6) manufactured by Medtronic, Inc. (Minneapolis, Minnesota), and the 1763 (n 5 1), 1782 (n 5 2), 1790 (n 5 1), and 1831 (n 5 1) manufactured by Guidant Corp. (St. Paul, Minnesota). All patients had DFTs determined at the time of device implant using a sequential “change in delivered energy” protocol from an initial delivered energy of 15 J with decrements or increments of 5 J. Ventricular fibrillation was induced using a T-wave shock. The lowest energy required for cardioversion was considered the DFT.8 No patient was receiving antiarrhythmic drugs other than b blockers (10 patients) at the time of initial device implant. The indication for amiodarone was recurrent ventricular tachycardia in 12 patients and atrial fibrillation in 6. The drug was loaded orally in the hospital for a total dose of 8 to 12 g over 6 to 10 days, followed by maintenance doses. Follow-up DFT determination was performed after the oral load using the same protocol used at device implant. The Student’s t test for paired data was used to compare the DFTs from implant and after amiodarone loading. Data are expressed as mean 6 SD. A p value ,0.05 was considered statistically significant. The time between initial DFT determination and the DFT after amiodarone loading ranged from 1 to 32 months. The average time between studies was 226 6 248 days, with a median time of 146 days. In the overall group, the DFT increased significantly after amiodarone loading, from 10.5 6 4.7 to 15.2 6 7.8 J (p ,0.0015). In the subgroup of patients in whom the time between initial DFT determination and initiation of amiodarone was ,6 months (12 of the 18 patients), the DFT also increased from 10.8 6 5.3 to 16.1 6 8.6 J (p 5 0.005). The mean changes in DFT are shown in Figure 1. After loading, 11 of 18 patients had an increase in the DFT, 6 had no change, and 1 patient had a decrease from 10 to 5 J. In 1 patient, termination of amiodarone was required because the DFT after drug loading was unacceptably high (25 J). Individual changes in the DFT are displayed in Figure 2. • • • The main finding of our study was the demonstration of higher DFTs using biphasic energy waveforms after in-hospital oral amiodarone loading over several days. To our knowledge, this is the first time that the effect of short-term amiodarone oral loading on the biphasic DFT has been examined in humans. Although the results observed in our study could be attributed to other long-term physiologic differences (such as changes in ventricular size and ventricular function), we doubt this to be the case. Three of 6 patients who began therapy with amiodarone within 1 month of the initial device implantation had an increase in the DFT after drug loading, including 1 patient whose DFT was raised enough to render an inadequate safety margin. The difference in DFT was also significant in the group of patients in whom amiodarone was started within 6 months of implant. Although the increase in defibrillation energy requirements was statistically significant, it was not universal. One third of patients studied had no change in the DFT after drug initiation, and 1 patient had a From the Department of Internal Medicine (Cardiology, Clinical Cardiac Electrophysiology), The University of Texas Southwestern Medical Center; and The Dallas Veterans Affairs Medical Center, Dallas, Texas. Dr. Joglar’s address is: Division of Cardiology, Department of Internal Medicine, University of Texas Southwestern Medical Center, Room CS7.102, 5323 Harry Hines Boulevard, Dallas, Texas 753909047. E-mail: jajogl@parknet.pmh.org. Manuscript received September 14, 2000; revised manuscript received and accepted March 27, 2001.

Fainting is a major healthcare problem with significant morbidity, mortality, and healthcare cost. We sought to assess the appropriateness of current clinical practice when compared to a guideline-based algorithm.The records of 100 consecutive patients who presented with faint and were referred to the University of Utah for further evaluation by specialists were reviewed. We analyzed the clinical characteristics, tests performed, diagnosis made, and number of admissions. In addition, we applied a guideline-based algorithm to assess the appropriateness of these evaluations.The mean age was 49 ± 21 years with 57% being female. One-third presented with their first event. Structural heart disease was present in 22% of the cases. Twelve (36%) of 32 admissions were inappropriate. There was an underutilization of orthostatic testing, carotid sinus massage, and implantable loop recorder and overutilization of imaging studies and neurologic consultation. Specifically, active standing and tilt-table testing were performed in only 24% and 7% of the cases, respectively, none of the patients had carotid sinus massage despite 26% of them being ≥65 years old, and only 3% of the patients received an implantable loop recorder. With the current practice, a final diagnosis was made in 45 cases with 17 (38%) of the 45 final diagnoses not being sufficiently supported by the completeness of the evaluation.With the current practice at a major university hospital, the cause of faint was unexplained in a high number of cases. Our findings highlight the need for a standardized approach to patients presenting with faint.

Ectopy-induced cardiomyopathy is an increasingly recognized cause of reversible left ventricular (LV) dysfunction. The underlying mechanisms remain unknown. Our goal was to create an animal model for ectopy-induced cardiomyopathy.Eleven mongrel dogs underwent the implantation of a dual-chamber pacemaker. Four dogs served as the control group and seven as the paced group. In the paced group, the pacemaker was connected to two endocardial right ventricular leads, one inserted into the atrial port and the other one into the ventricular port with an atrioventricular delay adjusted to ensure the presence of coupled pacing simulating ventricular bigeminy. Echocardiographic measurements of LV size (LV end-diastolic diameter [LV-EDD], LV end-systolic diameter [LV-ESD]), LV ejection fraction (LVEF), and mitral regurgitation (MR) were obtained at baseline and after 4 weeks of monitoring or pacing in all dogs except one who had lead dislodgement.In the control group (n = 4), no significant changes in LV dimensions or function were noted. In the paced group (n = 6), LV-EDD and LV-ESD increased from 3.58 ± 0.65 cm and 2.47 ± 0.55 cm to 4.15 ± 0.59 cm and 3.21 ± 0.47 cm, respectively (P0.01). In addition, LVEF decreased from 60 ± 7% to 46 ± 9% (P0.05). No changes in MR were noted.We have shown that coupled pacing simulating ventricular bigeminy was feasible and resulted in increased LV dimensions and decreased LV function. By controlling the percentage of pacing, the coupling interval and the location of the pacing lead, this new model will allow the assessment of the relative roles of these variables in the development of ectopy-induced cardiomyopathy.

Atrial fibrillation (AF) has been shown to be associated with reduced survival and increased ventricular arrhythmogenesis. The purpose of this study was to assess the effects of AF with adequate rate control on the electrophysiologic properties of the ventricles. We hypothesized that AF results in increased ventricular arrhythmogenic risk and that reverse remodeling occurs post-successful cardioversion.In nine patients with persistent AF, we recorded 12-lead electrocardiograms (ECGs) and 1-hour high-resolution Holter ECGs (H12+, Mortara Instrument, Inc. Milwaukee, WI, USA; recorders [1000 sps] immediately following cardioversion (Day 1) and after 30 days of maintaining sinus rhythm (Day 30). We measured QTc, QT dispersion, and calculated estimates of mean ventricular action potential duration (RT), diastolic interval (DI), T-wave width (TW), T-wave peak-to-end, and their respective scatter on Day 1 and Day 30. Maintenance of normal sinus rhythm was confirmed with a weekly trans-telephonic ECG transmission.The average QTc interval decreased from 449 ± 28 ms on Day 1 to 422 ± 36 ms on Day 30 (P = 0.04). There was no significant difference in the average QT dispersion. A significant decrease was also noted in DI and TW scatter at Day 30 when compared with Day 1 (P = 0.03 and 0.04, respectively). A decrease in RT scatter was also noted albeit not statistically significant (P = 0.07).Our results suggest a greater propensity to ventricular arrhythmogenesis in the immediate period following restoration of sinus rhythm and reverse electrical remodeling of the ventricles during the first month after successful maintenance of sinus rhythm. (PACE 2010; 33:1198-1202).

A 53-year-old man developed a deep venous thrombus (DVT) and pulmonary embolism (PE) shortly after an open Roux-en-Y gastric bypass was performed. He later suffered a life-threatening gastrointestinal bleed while on anticoagulation for the DVT. Thus, anticoagulation was held and an inferior vena cava (IVC) filter (G2, Bard Inc., Tempe, AZ, USA) was placed for PE prophylaxis. About 10 days after filter placement, he presented with severe low back pain and syncope. He also presented with hypotension and anuria unresponsive to intravenous fluids. A STAT non-contrast CT scan of the abdomen revealed that his IVC filter had migrated from an infrarenal to a suprarenal position. Given the high clinical suspicion for renal vein thrombosis, an attempt at IVC filter retrieval was made. The filter could not be retrieved because it was embedded in a large IVC thrombus that extended from the hepatic veins down to the common iliac veins. The patient received nearly 4 days of tPA that was administered at the site of the thrombus with a long thrombolytic catheter (UNIFUSE, Angiodynamics, Queensbury, NY, USA). While his creatinine peaked at 7.6 on hospital Day 4, he eventually began to produce urine and his creatinine had declined to his baseline of 1.0 on follow-up 1 month later. About 18 months after admission, his creatinine had further declined to 0.8. We report the first published case of acute renal failure due to bilateral renal vein thrombosis in the setting of IVC filter migration and thrombosis. This report highlights an important, but rare complication of IVC filter placement as well as the non-operative management of acute bilateral renal vein thrombosis.

Obesity is associated with significantly increased cardiovascular mortality that has been attributed, in part, to sympathetic activation. Gastric bypass surgery (GBS) appears to increase long-term survival in the severely obese, but the mechanisms responsible for this increase are still being sought. Heart rate (HR) recovery after exercise reflects the balance of cardiac autonomic input from the sympathetic and parasympathetic systems. Blunted HR recovery is a very powerful predictor of increased mortality, whereas enhanced HR recovery portends a good prognosis.The purpose of this study was to evaluate the effect of marked weight loss achieved via GBS on HR recovery.Severely obese patients underwent submaximal exercise testing (80% predicted maximum HR) at baseline and 2 years after GBS (n = 153) or nonsurgical treatment (n = 188).Patients in the GBS group lost an average of 100 ± 37 lb compared to 3 ± 22 lb in the nonsurgical group (P.001, GBS vs nonsurgical). Resting HR decreased from 73 bpm to 60 bpm in the GBS group and from 74 bpm to 68 bpm in nonsurgical patients (P.001). HR recovery improved by 13 bpm in the GBS group but did not change in the nonsurgical group (P.001 GBS vs nonsurgical). In multivariable analysis, the independent correlates of HR recovery at the 2-year time point were resting HR, treadmill time, age, body mass index, and HOMA-IR (an index of insulin resistance).Marked weight loss 2 years after GBS resulted in a significant decrease in resting HR and an enhancement in HR recovery after exercise. These changes likely are attributable to improvement in insulin sensitivity and cardiac autonomic balance. Whether and to what extent this contributes to a reduction in cardiovascular mortality with GBS remains to be determined.

The von Mises coordinates are employed in the numerical study of viscous fluid flow through porous domains possessing curved, solid boundaries along which a no-slip condition is imposed. A numerical procedure is proposed to account for the infinite Jacobian of the transformation, which arises due to this no-slip condition. To illustrate this idea, two dimensional viscous fluid flow through a porous channel bounded by a lower and an upper curved, solid wall is considered. The effects of the grid size and the horizontal extent of the computational domain are illustrated.

The current investigation deals with the study of the effect of introducing a small fraction of dust, by volume, to the fluid in a squeeze film on the viscous resistance to a steady moving disc. Expressions are obtained for the fluid-phase and the dust-phase velocity distributions and the dust particle number density. Analysis based on an iterative procedure indicates that the resistance to motion experienced by the moving disc increases due to the presence of dust.

Numerical implementation of the von Mises transformation in porous media flow has been illustrated using the Darcy model. Flow through a semi-finite porous block bounded below by an impermeable wall of arbitrary shape has been analysed by a finite-difference method. The use of the von Mises transformation eliminates any need to numerically generate a grid system.

A numerical method to handle the flow of a two-phase fluid over curved boundaries is proposed. The method is based on the double von Mises transformation which is derived in this work and is expected to be applicable to a variety of flow situations while utilizing the finite difference technique. In order to illustrate the numerical implementation of the method, dusty fluid flow through a porous channel possessing curved boundaries and the flow through a semi-infinite porous layer overlying a curved lower boundary are considered. The flow is assumed to be governed by model equations based on Brinkman's equation and reflecting boundary conditions are employed in the study based on a uniform dust particle distribution. Results indicate that an increase in the permeability results in decreasing the tangential velocity component in regions close to the curved boundary, and increasing the dust parameters decreases this component. The effects of the grid size and the extent of the computational domain are discussed. The results also shed some light on the applicability of the dusty fluid flow model and suggest that the model is best employed when the permeability is high, a conclusion that is consistent with the validity of Brinkman's equation.