Search

Background: Computed tomography (CT)-based fat and muscle measures are associated with outcome in large populations. We tested if muscle and fat characteristics are associated with long-term outcomes after TAVR., Methods: We included 403 clinical CTs performed prior to TAVR at our center between 2008 and 2016, measuring area (cm 2 ) and density (Hounsfield units, HU) of both psoas muscles (PM), subcutaneous adipose (SAT), and visceral adipose tissue (VAT). Area measures were indexed to height, log-transformed and both area and density were standardized for analysis. We assessed the association of each measure with all-cause mortality (adjusted for age, sex, body mass index (BMI), and the Society of Thoracic Surgeons (STS) risk score., Results: Of the 403 individuals (83 ± 8 years; 52% female), 167 (41.4%) died during a median follow-up of 458 days (interquartile range IQR 297-840). Fat measures were feasible and rapid. Fat area was available in 242 (60%) patients with an adequate field of view. Individuals with the lowest PM area, SAT area or VAT area exhibited the highest hazard of mortality. In addition, greater SAT density was associated with a higher mortality hazard (adjusted HR per standard deviation increase in density = 1.35, 95%CI 1.10-1.67, P = 0.005)., Conclusion: Rapid CT-based tissue characterization is feasible in patients referred for TAVR. Decreased PM area and increased SAT density are associated with long-term mortality after TAVR, even after accounting for age, sex, BMI, and STS score. Further studies are necessary to interrogate sex-specific relationships between CT tissue metrics and mortality and whether CT measures are incremental to well-established frailty metrics., (Copyright © 2018 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.)

Background: We present the formulation and testing of a new CT angiography (CTA)-based method for noninvasive measurement of absolute coronary blood flow (CBF) termed transluminal attenuation flow encoding (TAFE). CTA provides assessment of coronary plaque but does not allow for detection of vessel specific ischemia. A simple and direct method to calculate absolute CBF from a standard CTA could isolate the functional consequence of disease and aid therapy decisions., Methods: We present the theoretical framework and initial testing of TAFE. Nine canine models of ischemic heart disease were prepared and underwent CT imaging and microsphere measurements of myocardial blood flow. Additionally, 39 acute chest pain patients with normal coronary arteries underwent coronary CTA. We applied TAFE to calculate absolute CBF in the coronary arteries using 4 vessel input parameters including transluminal attenuation gradient, cross-sectional area, length, and the contrast bolus duration derived from the arterial input function., Results: In animal studies, TAFE-derived CBF in the left anterior descending, left circumflex, and right coronary artery was 20.8 ± 10.4 mL/min, 27.0 ± 13.4 mL/min, and 6.0 ± 3.7 mL/min, respectively. TAFE-derived CBF divided by myocardial mass strongly correlated with microsphere myocardial blood flow (R(2) = 0.90, P < .001). In human studies, TAFE-derived CBF in the left anterior descending, left circumflex, and right coronary artery was 26.4 ± 10.7 mL/min, 20.1 ± 13.0 mL/min, and 43.2 ± 40.9 mL/min, respectively. CBF per unit mass was 0.93 ± 0.48 mL/g/min in patients. Interobserver variability was minimal with excellent correlation (R = 0.96, P < .0001) and agreement (mean difference, 4.2 mL/min)., Conclusion: TAFE allows for quantification of absolute CBF from a standard CTA acquisition and may provide functional significance of coronary disease without complex computational methods., (Copyright © 2015 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.)

Background: Infarcted regions of myocardium exhibit functional impairment ranging in severity from hypokinesis to dyskinesis. We sought to quantify the effects of injecting a calcium hydroxyapatite-based tissue filler on the passive material response of infarcted left ventricles., Methods: Three-dimensional finite element models of the left ventricle were developed using three-dimensional echocardiography data from sheep with a treated and untreated anteroapical infarct, to estimate the material properties (stiffness) in the infarct and remote regions. This was accomplished by matching experimentally determined left ventricular volumes, and minimizing radial strain in the treated infarct, which is indicative of akinesia. The nonlinear stress-strain relationship for the diastolic myocardium was anisotropic with respect to the local muscle fiber direction, and an elastance model for active fiber stress was incorporated., Results: It was found that the passive stiffness parameter, C, in the treated infarct region is increased by nearly 345 times the healthy remote value. Additionally, the average myofiber stress in the treated left ventricle was significantly reduced in both the remote and infarct regions., Conclusions: Overall, injection of tissue filler into the infarct was found to render it akinetic and reduce stress in the left ventricle, which could limit the adverse remodeling that leads to heart failure., (Copyright © 2011 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.)