A Man in His 30s With Splenic Infarct and Stroke.

This case report describes a diagnosis of quadricuspid aortic valve in a man in his 30s with a history of splenic infarct who presented with right-sided ischemic stroke.

Combining Statistical Shape Model and Principal Component Analysis to Estimate Left Ventricular Volume and Ejection Fraction.

Left ventricular ejection fraction (LVEF) assessment is instrumental for cardiac health diagnosis, patient management, and patient eligibility for participation in clinical studies. Due to its non-invasiveness and low operational cost, ultrasound (US) imaging is the most commonly used imaging modality to image the heart and assess LVEF. Even though 3D US imaging technology is becoming more available, cardiologists dominantly use 2D US imaging to visualize the LV blood pool and interpret its area changes between end-systole and end-diastole. Our previous work showed that LVEF estimates based on area changes are significantly lower than the true volume-based estimates by as much as 13%,1 which could lead to unnecessary and costly therapeutic decisions. Acquiring volumetric information about the LV blood pool necessitates either time-consuming 3D reconstruction or 3D US image acquisition. Here, we propose a method that leverages on a statistical shape model (SSM) constructed from 13 landmarks depicting the LV endocardial border to estimate a new patient's LV volume and LVEF. Two methods to estimate the 3D LV geometry with and without size normalization were employed. The SSM was built using the 13 landmarks from 50 training patient image datasets. Subsequently, the Mahalanobis distance (with size normalization) or the vector distance (without size normalization) between an incoming patient's LV landmarks and each shape in the SSM were used to determine the weights each training patient contributed to describing the new, incoming patient's LV geometry and associated blood pool volume. We tested the proposed method to estimate the LV volumes and LVEF for 16 new test patients. The estimated LVEFs based on Mahalanobis distance and vector distance were within 2.9% and 1.1%, respectively, of the ground truth LVEFs calculated from the 3D reconstructed LV volumes. Furthermore, the viability of using fewer principal components (PCs) to estimate the LV volume was explored by reducing the number of PCs retained when projecting landmarks onto PCA space. LVEF estimated based on 3 PCs, 5 PCs, and 10 PCs are within 6.6%, 5.4%, and 3.3%, respectively, of LVEF estimates using the full set of 39 PCs.

Left Ventricular Ejection Fraction Assessment: Unraveling the Bias between Area- and Volume-based Estimates.

Calculating left ventricular ejection fraction (LVEF) accurately is crucial for the clinical diagnosis of cardiac disease, patient management, or other therapeutic treatment decisions. The measure of a patient's LVEF often affects their candidacy for cardiovascular intervention. Ultrasound (US) is one of the imaging modalities used to non-invasively assess LVEF, and it is the most common and least expensive. Despite the advances in 3D US transducer technology, only limited US machines are equipped with such transducer to enable true 3D US image acquisition. Thus, 2D US images remain to be widely used by cardiologists to image the heart and their interpretation is inherently based on two dimensional information immediately available in the US images. Past knowledge indicates that visual estimation of the LVEF based on the area changes of the left ventricle blood pool between systole and diastole (as depicted in 2D ultrasound images) may significantly underestimate the ejection fraction, rendering some patients as suitable candidates for potentially unnecessary interventions or implantation of assistive devices. True LVEF should be calculated based on changes in LV volumes, but equipment and time constraint limit the current technique to assess 3D LV geometry. The estimation of the systolic and diastolic blood pool volumes requires additional work beyond a simple visual assessment of the blood pool area changed in the 2D US images. Specifically, following the manual segmentation of the endocardial LV border, 3D volume would be assessed by reconstructing a LV volume from multiple tomographic views. In this work, we leverage on two idealized mathematical models of the left ventricle - a truncated prolate spheroid (TPS) and a paraboloid geometric model to characterize the LV shape according to the range of possible dimensions gathered from our patient-specific multi-plane US imaging data. The objective of this work is to reveal the necessity of calculating LVEFs based on volumes by showing that LVEF estimated using area changes underestimate the LVEF computed using volume changes. Additionally, we present a method to reconstruct the LV volume from 2D blood pool representations identified in the multi-plane 2D US images and use the reconstructed 3D volume throughout the cardiac cycle to estimate the LVEF. Our preliminary results show that the area-based LVEF significantly underestimates the true volume-based LVEF across both the theoretical simulations using idealized geometric models of the LV shape, as well as the patient-specific US imaging data. Specifically, both the TPS and paraboloid model showed an area-based LVEF of 41.3 ± 4.7% and a volume-based LVEF of 55.4 ± 5.7%, while the US image data showed an area-based LVEF of 34.7 ± 11.9% and a volume-based LVEF of 48.0 ± 14.0%. In summary, the area-based LVEF estimations using both the idealized TPS and paraboloid models was 14.1% lower than volume- based LVEF calculations using corresponding models. Furthermore, the area-based LVEF based on reconstructed LV volumes are 13.3% lower than volume-based estimates. Evidently, there is a need to further investigate a method to enable practical volume-based LVEF calculations to avoid the need for clinicians to estimate LVEF based on visual, holistic assessment of the blood pool area changes that improperly infer volumetric blood pool changes.

In-Home Cardiovascular Monitoring System for Heart Failure: Comparative Study.

BACKGROUND: There is a pressing need to reduce the hospitalization rate of heart failure patients to limit rising health care costs and improve outcomes. Tracking physiologic changes to detect early deterioration in the home has the potential to reduce hospitalization rates through early intervention. However, classical approaches to in-home monitoring have had limited success, with patient adherence cited as a major barrier. This work presents a toilet seat-based cardiovascular monitoring system that has the potential to address low patient adherence as it does not require any change in habit or behavior. OBJECTIVE: The objective of this work was to demonstrate that a toilet seat-based cardiovascular monitoring system with an integrated electrocardiogram, ballistocardiogram, and photoplethysmogram is capable of clinical-grade measurements of systolic and diastolic blood pressure, stroke volume, and peripheral blood oxygenation. METHODS: The toilet seat-based estimates of blood pressure and peripheral blood oxygenation were compared to a hospital-grade vital signs monitor for 18 subjects over an 8-week period. The estimated stroke volume was validated on 38 normative subjects and 111 subjects undergoing a standard echocardiogram at a hospital clinic for any underlying condition, including heart failure. RESULTS: Clinical grade accuracy was achieved for all of the seat measurements when compared to their respective gold standards. The accuracy of diastolic blood pressure and systolic blood pressure is 1.2 (SD 6.0) mm Hg (N=112) and -2.7 (SD 6.6) mm Hg (N=89), respectively. Stroke volume has an accuracy of -2.5 (SD 15.5) mL (N=149) compared to an echocardiogram gold standard. Peripheral blood oxygenation had an RMS error of 2.3% (N=91). CONCLUSIONS: A toilet seat-based cardiovascular monitoring system has been successfully demonstrated with blood pressure, stroke volume, and blood oxygenation accuracy consistent with gold standard measures. This system will be uniquely positioned to capture trend data in the home that has been previously unattainable. Demonstration of the clinical benefit of the technology requires additional algorithm development and future clinical trials, including those targeting a reduction in heart failure hospitalizations.

A Statistical Shape Model Approach for Computing Left Ventricle Volume and Ejection Fraction Using Multi-plane Ultrasound Images.

Assessing the left ventricular ejection fraction (LVEF) accurately requires 3D volumetric data of the LV. Cardiologists either have no access to 3D ultrasound (US) systems or prefer to visually estimate LVEF based on 2D US images. To facilitate the consistent estimation of the end-diastolic and end-systolic blood pool volume and LVEF based on 3D data without extensive complicated manual input, we propose a statistical shape model (SSM) based on 13 key anchor points-the LV apex (1), mitral valve hinges (6), and the midpoints of the endocardial contours (6)-identified from the LV endocardial contour of the tri-plane 2D US images. We use principal component analysis (PCA) to identify the principle modes of variation needed to represent the LV shapes, which enables us to estimate an incoming LV as a linear combination of the principle components (PC). For a new, incoming patient image, its 13 anchor points are projected onto the PC space; its shape is compared to each LV shape in the SSM based on Mahalanobis distance, which is normalized with respect to the LV size, as well as direct vector distance (i.e., PCA distance), without any size normalization. These distances are used to determine the weight each training shape in the SSM contributes to the description of the new patient LV shape. Finally, the new patient's LV systolic and diastolic volumes are estimated as the weighted average of the training volumes in the SSM. To assess our proposed method, we compared the SSM-based estimates of diastolic, systolic, stroke volumes, and LVEF with those computed directly from 16 tri-plane 2D US imaging datasets using the GE Echo-Pac PC clinical platform. The estimated LVEF based on Mahalanobis distance and PCA distance were within 6.8% and 1.7% of the reference LVEF computed using the GE Echo-Pac PC clinical platform.

Toward Quantification and Visualization of Active Stress Waves for Myocardial Biomechanical Function Assessment.

Estimating and visualizing myocardial active stress wave patterns is crucial to understanding the mechanical activity of the heart and provides a potential non-invasive method to assess myocardial function. These patterns can be reconstructed by analyzing 2D and/or 3D tissue displacement data acquired using medical imaging. Here we describe an application that utilizes a 3D finite element formulation to reconstruct active stress from displacement data. As a proof of concept, a simple cubic mesh was used to represent a myocardial tissue "sample" consisting of a 10 × 10 × 10 lattice of nodes featuring different fiber directions that rotate with depth, mimicking cardiac transverse isotropy. In the forward model, tissue deformation was generated using a test wave with active stresses that mimic the myocardial contractile forces. The generated deformation field was used as input to an inverse model designed to reconstruct the original active stress distribution. We numerically simulated malfunctioning tissue regions (experiencing limited contractility and hence active stress) within the healthy tissue. We also assessed model sensitivity by adding noise to the deformation field generated using the forward model. The difference image between the original and reconstructed active stress distribution suggests that the model accurately estimates active stress from tissue deformation data with a high signal-to-noise ratio.

Nontraditional Electrocardiogram and Algorithms for Inconspicuous In-Home Monitoring: Comparative Study.

BACKGROUND: Wearable and connected in-home medical devices are typically utilized in uncontrolled environments and often measure physiologic signals at suboptimal locations. Motion artifacts and reduced signal-to-noise ratio, compared with clinical grade equipment, results in a highly variable signal quality that can change significantly from moment to moment. The use of signal quality classification algorithms and robust feature delineation algorithms designed to achieve high accuracy on poor quality physiologic signals can prove beneficial in addressing concerns associated with measurement accuracy, confidence, and clinical validity. OBJECTIVE: The objective of this study was to demonstrate the successful extraction of clinical grade measures using a custom signal quality classification algorithm for the rejection of poor-quality regions and a robust QRS delineation algorithm from a nonstandard electrocardiogram (ECG) integrated into a toilet seat; a device plagued by many of the same challenges as wearable technologies and other Internet of Things-based medical devices. METHODS: The present algorithms were validated using a study of 25 normative subjects and 29 heart failure (HF) subjects. Measurements captured from a toilet seat-based buttocks electrocardiogram were compared with a simultaneously captured 12-lead clinical grade ECG. The ECG lead with the highest morphological correlation to buttocks electrocardiogram was used to determine the accuracy of the heart rate (HR), heart rate variability (HRV), which used the standard deviation of the normal-to-normal (SDNN) intervals between sinus beats, QRS duration, and the corrected QT interval (QTc). These algorithms were benchmarked using the MIT-BIH Arrhythmia Database (MITDB) and European ST-T Database (EDB), which are standardized databases commonly used to test QRS detection algorithms. RESULTS: Clinical grade accuracy was achieved for all buttocks electrocardiogram measures compared with standard Lead II. For the normative cohort, the mean was -0.0 (SD 0.3) bpm (N=141 recordings) for HR accuracy and -1.0 (SD 3.4) ms for HRV (N=135). The QRS duration and the QTc interval had an accuracy of -0.5 (SD 6.6) ms (N=85) and 14.5 (SD 11.1) ms (N=85), respectively. In the HF cohort, the accuracy for HR, HRV, QRS duration, and QTc interval was 0.0 (SD 0.3) bpm (N=109), -6.6 (SD 13.2) ms (N=99), 2.9 (SD 11.5) ms (N=59), and 11.2 (SD 19.1) ms (N=58), respectively. When tested on MITDB and EDB, the algorithms presented herein had an overall sensitivity and positive predictive value of over 99.82% (N=900,059 total beats), which is comparable to best in-class algorithms tuned specifically for use with these databases. CONCLUSIONS: The present algorithmic approach to data analysis of noisy physiologic data was successfully demonstrated using a toilet seat-based ECG remote monitoring system. This approach to the analysis of physiologic data captured from wearable and connected devices has future potential to enable new types of monitoring devices, providing new insights through daily, inconspicuous in-home monitoring.

LEFT VENTRICULAR EJECTION FRACTION: COMPARISON BETWEEN TRUE VOLUME-BASED MEASUREMENTS AND AREA-BASED ESTIMATES.

Left ventricular ejection fraction (LVEF) is a critical measure of cardiac health commonly acquired in clinical practice, which serves as the basis for cardiovascular therapeutic treatment. Ultrasound (US) imaging of the heart is the most common, least expensive, reliable and non-invasive modality to assess LVEF. Cardiologists, in practice, persistently use 2D US images to provide visual estimates of LVEF, which are based on 2D information embedded in the US images by examining the area changes in LV blood pool between diastole and systole. There has been some anecdotal evidence that visual estimation of the LVEF based on the area changes of the LV blood pool significantly underestimate true LVEF. True LVEF should be calculated based on changes in LV volumes between diastole and systole. In this project, we utilized both idealized models of the LV geometry - a truncated prolate spheroid (TPS) and a paraboloid model - to represent the LV anatomy. Cross-sectional areas and volumes of simulated LV shapes using both models were calculated to compare the LVEF. Further, a LV reconstruction algorithm was employed to build the LV blood pool volume in both systole and diastole from multi-plane 2D US imaging data. Our mathematical models yielded an area-based LVEF of 41 4.7% and a volume-based LVEF of 55 ±5.7%, while the 3D recon-struction model showed an area-based LVEF of 35 11.9% and a volume-based LVEF of 48.0 ± 14.0%. In summary, the area-based LVEF using all three models ±underestimate the volume-based LVEF using corresponding models by 13% to 14%. This preliminary study confirms both mathematically and empirically that area-based LVEF estimates indeed underestimate the true volume-based LVEF measurements and suggests that true volumetric measurements of the LV blood pool must be computed to correctly assess cardiac LVEF.

Identification of Left Ventricle Failure on Pulmonary Artery CTA: Diagnostic Significance of Decreased Aortic & Left Ventricle Enhancement.

PURPOSE: This study aimed to identify findings on non-ECG-gated CT pulmonary angiography (CTPA) indicating decreased left ventricle (LV) systolic function, later confirmed by echocardiogram. METHODS: After obtaining institutional review board approval, review was performed of emergency department (ED) patients who had CTPA and follow-up echocardiogram within 48 h, over 18 months. Patients with pulmonary embolus, suboptimal CTPA, arrhythmias or pericardial tamponade were excluded. One hundred thirty-seven patients were identified and divided into cases (LVEF <40%, n = 52) and controls (LVEF >50%, n = 85). Two reviewers performed these analyses: measurement of enhancement in main pulmonary artery (MPA), LV, and aorta; subjective enhancement of LV and aorta (Ao) relative to MPA using a four-point Likert scale; contrast transit time (TD) to trigger CTPA and LV short & long axis dimensions. When available, the most recent N-terminal pro-B-type natriuretic peptide (NT-proBNP) level was recorded. RESULTS: Decreased aortic and LV subjective enhancement were the best predictors of LV systolic dysfunction. For Ao/MPA ratio, an optimal cutoff value of 0.20 resulted in a sensitivity of 0.54 and specificity of 0.93 (AUC = 0.83, 0.78-0.88 95% CI). A threshold of 86.7 HU for Ao enhancement resulted in a sensitivity of 0.68 and specificity of 0.90 (AUC = 0.82, 0.77-0.88 95% CI). A LV short axis diameter of more than 54.3 mm had a sensitivity of 0.62 and specificity of 0.98 (AUC = 0.88, 0.83-0.92 95% CI). For the LV long axis diameter, a cutoff of 87.5 mm resulted in a sensitivity of 0.66 and specificity of 0.84 (AUC = 0.78, 0.72-0.84 95% CI). With bolus timing, cases had a longer TD (13.4 vs. 10.4 s, p < 0.0001). CONCLUSION: Unsuspected LV systolic dysfunction can be recognized on a CTPA by identification of decreased aortic enhancement, LV enlargement and increased TD. This has important diagnostic implications for the patient presenting with shortness of breath, chest pain, or dyspnea.

Left Ventricular Systolic Function Assessed by Global Longitudinal Strain is Impaired in Atrial Fibrillation Compared to Sinus Rhythm.

BACKGROUND: Atrial fibrillation (AF) is the most common aberrant cardiac arrhythmia. Many AF patients present with symptoms of dyspnea and fatigue, but have normal left ventricular ejection fraction (LVEF). PURPOSE: To determine the reproducibility of measurements of global longitudinal strain (GLS) and strain rate in patients with AF and examine if the arrhythmia is associated with abnormal LV strain and strain rate independent of age, sex, heart rate, LVEF and LV mass. We hypothesized that AF independently reduces ventricular systolic performance. METHODS: The study was conducted as a retrospective analysis of images from 150 randomly selected patients with AF compared to an equal number of subjects with sinus rhythm (SR) matched for age, sex, heart rate, LVEF and LV mass. Half of the patients had normal LVEF (LVEF > 50%) and half had reduced LVEF (LVEF < 50%). GLS and strain rate were measured in each group, as were quantitative LV volumes and standard systolic and diastolic parameters. Results: GLS was significantly impaired in patients with AF compared to subjects with SR, both in the overall population (-12.25 ± 4.1% vs. -16.13 ± 4.7%, p<0.0001), in patients with normal LVEF (-14.41 ± 3.9% vs. -19.42 ± 3.1%, p<0.0001) and in patients with reduced LVEF (-10.10 ± 3.1% vs. -12.85 ± 3.5%, p<0.0001).Linear regression and Bland Altman analyses demonstrated good intraobserver and interobserver agreement for measurements of GLS and strain rate parameters even in patients with AF.

Prevalence of Non-Left Anterior Descending Septal Perforator Culprit in Patients With Hypertrophic Cardiomyopathy Undergoing Alcohol Septal Ablation.

Identifying the coronary branch that supplies the basal septum is the cornerstone for successful alcohol septal ablation (ASA). The basal septum is often supplied by septal perforator artery/arteries (SPA/SPAs) not originating from the left anterior descending (LAD) coronary artery. We aim to investigate the prevalence and significance of non-LAD septal "culprit" in patients undergoing ASA. A retrospective review of patients who underwent ASA from 2006 to 2014 was conducted. Procedural and midterm outcomes of patients who had ASA of LAD and non-LAD culprit SPA were reported. A total 89 patients were included in the analysis; 13 patients (15%) had ASA of non-LAD SPA. These patients were more likely to have a history of failed ASA, more than one SPA treated, more ethanol dose injected, longer procedures, and higher contrast use compared with those who had ASA of LAD-SPA. In-hospital outcomes, residual gradient, symptom improvement, and midterm mortality were similar in the 2 groups. In conclusion, in a cohort of patients undergoing ASA, 15% had ablation of SPA culprit that did not originate from the LAD. Half of these patients had previous unsuccessful ASA. Systematic screening for the ideal culprit SPA with nonselective coronary injection of echo contrast should be used to avoid incomplete or failed ASA.

Long-term total cardiac support in a Fontan-type circulation with HeartMate II left ventricular assist device.

Interest in utilizing long-term mechanical circulatory support for Fontan-type circulation has been high. Unfortunately, so far such attempts have not been successful. Herein, we are presenting the first case of an individual with biventricular heart failure and Fontan-type circulation on long-term mechanical circulatory support with a continuous-flow left ventricular assist device.

Pulse Wave Velocity Prediction and Compliance Assessment in Elastic Arterial Segments.

Pressure wave velocity (PWV) is commonly used as a clinical marker of vascular elasticity. Recent studies have increased clinical interest in also analyzing the impact of heart rate, blood pressure, and left ventricular ejection time on PWV. In this article we focus on the development of a theoretical one-dimensional model and validation via direct measurement of the impact of ejection time and peak pressure on PWV using an in vitro hemodynamic simulator. A simple nonlinear traveling wave model was developed for a compliant thin-walled elastic tube filled with an incompressible fluid. This model accounts for the convective fluid phenomena, elastic vessel deformation, radial motion, and inertia of the wall. An exact analytical solution for PWV is presented which incorporates peak pressure, ejection time, ejection volume, and modulus of elasticity. To assess arterial compliance, the solution is introduced in an alternative form, explicitly determining compliance of the wall as a function of the other variables. The model predicts PWV in good agreement with the measured values with a maximum difference of 3.0%. The results indicate an inverse quadratic relationship ([Formula: see text]) between ejection time and PWV, with ejection time dominating the PWV shifts (12%) over those observed with changes in peak pressure (2%). Our modeling and validation results both explain and support the emerging evidence that, both in clinical practice and clinical research, cardiac systolic function related variables should be regularly taken into account when interpreting arterial function indices, namely PWV.

Predictors of mortality in patients hospitalized for congestive heart failure with left ventricular ejection fraction ≥ 40.

BACKGROUND: There are limited data regarding the predictors of mortality in patients with acute congestive heart failure (CHF) and left ventricular ejection fraction (LVEF) ≥ 40%. METHODS: We evaluated clinical characteristics, mortality and prognostic factors in a sample of consecutive patients hospitalized for CHF with LVEF ≥ 40%. Multivariable Cox regression models were developed to predict mortality using baseline clinical characteristics and echocardiographic variables. RESULTS: The study population consisted of 191 patients, mean age 70 ± 14.6 years (60% female) with average follow-up of 4.0 ± 2.8 years. Cumulative 5-year mortality was 58% in the entire population and it was 59% in men and 57% in women (p = 0.411). In multivariable analyses, predictors of mortality were the following: blood urea nitrogen (BUN) > 25 mg/dL (HR = 1.77; p = 0.002); absence of hypertension (HR = 1.58; p = 0.032), left ventricular end diastolic dimension (LVEDD) ≤ 4.1 cm (HR = 1.73; p = 0.011) and LVEF ≤ 45% (HR = 1.69; p = 0.027). CONCLUSIONS: Patients hospitalized for heart failure with LVEF ≥ 40% have very high mortality. Absence of hypertension, elevated BUN and lower LVEF ≤ 45% indicate increased risk of short- and long-term mortality. Lower LVEDD is an independent predictor of mortality in heart failure patients with LVEF ≥ 40%.

Evaluation and treatment of pump thrombosis and hemolysis.

Ventricular assist devices (VADs) are not fully biocompatible, and are therefore predisposed to device thrombosis and subsequent pump dysfunction. Clinically significant hemolysis in VADs most often occurs as a result of device thrombosis, but can also be caused by other factors. Herein we describe the evaluation and management of VAD thrombosis and hemolysis.

Ventricular assist device thrombosis following recovery of left ventricular function.

Although ventricular assist devices (VADs) are lifesaving therapy for patients with severe heart failure, complications such as pump thrombosis can occur. In this report, we present a case of VAD thrombosis following recovery of left ventricular (LV) function. The patient had been supported with a VAD for 8 months, and at the time of presentation, echocardiography revealed near normal native systolic function, aortic valve opening with significant native heart ejection, reduced systolic flow in the outflow and inflow cannulae, and no forward flow through the VAD during diastole. The patient underwent successful VAD explant and examination of the pump revealed thrombus on the rotor. We propose that abnormal flow through the VAD seen with recovery of LV function may contribute to VAD thrombosis.

In vitro hemodynamic model of the arm arteriovenous circulation to study hemodynamics of native arteriovenous fistula and the distal revascularization and interval ligation procedure.

BACKGROUND: Experimental modeling of arteriovenous hemodialysis fistula (AVF) hemodynamics is challenging. Mathematical modeling struggles to accurately represent the capillary bed and venous circulation. In vivo animal models are expensive and labor intensive. We hypothesized that an in vitro, physiologic model of the extremity arteriovenous circulation with provisions for AVF and distal revascularization and interval ligation (DRIL) configurations could be created as a platform for hemodynamic modeling and testing. METHODS: An anatomic, upper extremity arteriovenous model was constructed of tubing focusing on the circulation from the subclavian artery to subclavian vein. Tubing material, length, diameter, and wall thickness were selected to match vessel compliance and morphology. All branch points were constructed at physiologic angles. The venous system and capillary bed were modeled using tubing and one-way valves and compliance chambers. A glycerin/water solution was created to match blood viscosity. The system was connected to a heart simulator. Pressure waveforms and flows were recorded at multiple sites along the model for the native circulation, brachiocephalic AVF configuration, and the AVF with DR without and with IL (DR no IL and DRIL). RESULTS: A preset mean cardiac output of 4.2 L/min from the heart simulator yielded a subclavian artery pressure of 125/55 mm Hg and a brachial artery pressure of 121/54 mm Hg with physiologic arterial waveforms. Mean capillary bed perfusion pressure was 41 mm Hg, and mean venous pressure in the distal brachial vein was 17 mm Hg with physiologic waveforms. AVF configuration resulted in a 15% decrease in distal pressure and a 65% decrease in distal flow to the hand. DR no IL had no change in distal pressure with a 27% increase in distal flow. DRIL resulted in a 3% increase in distal pressure and a 15% increase in distal flow to the hand above that of DR no IL. Flow through the DR bypass decreased from 329 mL/min to 55 mL/min with the addition of IL. Flow through the AVF for both DR no IL and DRIL was preserved. CONCLUSIONS: Through the construction and validation of an in vitro, pulsatile arteriovenous model, the intricate hemodynamics of AVF and treatments for ischemic steal can be studied. DR with or without IL improved distal blood flow in addition to preserving AVF flow. IL decreased the blood flow through the DR bypass itself. The findings of the AVF as a pressure sink and the relative role of IL with DR bypass has allowed this model to provide hemodynamic insight difficult or impossible to obtain in animal or human models. Further study of these phenomena with this model should allow for more effective AVF placement and maturation while personalizing treatment for associated ischemic steal. CLINICAL RELEVANCE: The complications of arteriovenous fistula (AVF)-associated steal with its concurrent surgical treatments have been clinically described but have relatively little published, concrete hemodynamic data. A further understanding of the underlying hemodynamics is necessary to prevent the occurrence of steal and improve treatment when it occurs. Specific objectives are to study the blood flow through an AVF with varying anatomic and physiologic parameters, determine what factors contribute to the development of arterial steal distal to an AVF, and create optimal interventions to treat arterial steal from an AVF when it occurs. The long-term goal is creation of AVF tailored to patient-specific parameters, resulting in higher rates of functional fistulas with decreases in fistula-related complications. The ability to study fluid dynamics using a unique, in vitro, upper extremity pulsatile arteriovenous circulation simulator creates the ideal platform for this work.

Propranolol versus corticosteroids in the treatment of infantile hemangioma: a systematic review and meta-analysis.

BACKGROUND: Infantile hemangiomas are benign vascular neoplasms that can cause numerous functional or cosmetic problems. The authors reviewed the pathogenesis of hemangioma and compared the efficacy and complications related to therapy with propranolol versus corticosteroids. METHODS: A comprehensive review of the literature was conducted from 1965 to March of 2012 using MEDLINE, PubMed, Ovid, Cochrane Review database, and Google Scholar. All articles were reviewed for reports of clinical cases, reported side effects, doses, duration of treatment, number of patients, and response rate to treatment. RESULTS: A total of 1162 studies were identified. Of those, only 56 articles met inclusion criteria after review by two independent reviewers (A.I. and J.K.). For the meta-analysis, 16 studies comprising 2629 patients and 25 studies comprising 795 patients were included. Less than 90 percent of patients treated with corticosteroids responded to therapy, compared with 99 percent of patients treated with propranolol after 12 months of follow-up. Meta-analysis demonstrated the corticosteroid studies to have a pooled response rate of 69 percent versus the propranolol response rate of 97 percent (p < 0.001). CONCLUSIONS: Propranolol is a relatively recent therapy of hemangiomas with fewer side effects, a different mechanism of action, and greater efficacy than current first-line corticosteroid therapy. Many of these studies do not have the same patient population or duration/regimen of treatment for hemangiomas; however, based on available data in the literature, it appears that propranolol could be an emerging and effective treatment for infantile hemangiomas. Further randomized controlled trials are recommended.

Subcutaneous pre-expansion of mastectomy flaps before breast reconstruction with deep inferior epigastric perforator flaps: eliminating the patch-like appearance and improving aesthetic outcomes.

INTRODUCTION: Free tissue transfer and tissue expansion are important tools in the reconstructive surgeon's armamentarium, yet are not often used in conjunction. Although tissue transfer has its advantages, the patch-like appearance of the skin paddle on the breast can be unappealing. OBJECTIVE: To present our clinical experience of using subcutaneous breast tissue expansion before reconstruction with deep inferior epigastric perforator (DIEP) flaps, and to show how this technique eliminates the patch-like appearance of the skin paddle. METHODS: Five patients underwent delayed breast reconstruction using a 3-stage approach. During the first stage, tissue expanders were placed in the subcutaneous plane beneath the mastectomy flaps. After complete tissue expansion, the second stage involved removal of the tissue expanders and reconstruction of the breasts by burying deepithelialized DIEP flaps beneath the pre-expanded skin flaps. Revisions and nipple reconstructions were carried out in the third stage. Retrospective analysis of patients' characteristics, breast history, surgical stay, complications, and outcomes were performed. RESULTS: The patients were, on average, 49 years of age, with an average body mass index of 26.3. One patient underwent bilateral breast reconstruction whereas the rest had unilateral reconstructions. Two patients had minor complications. There were no DIEP failures or take-backs. CONCLUSION: Using subcutaneous breast tissue expansion followed by DIEP flap reconstruction can be performed safely, offering patients a completely autologous breast reconstruction with low morbidity, as well as eliminating the classical patch-like appearance of flap reconstructions.