Molecular Imaging for Efficacy of Pharmacologic Intervention in Myocardial Remodeling

ObjectivesUsing molecular imaging techniques, we examined interstitial alterations during postmyocardial infarction (MI) remodeling and assessed the efficacy of antiangiotensin and antimineralocorticoid intervention, alone and in combination.BackgroundThe antagonists of the renin-angiotensin-aldosterone axis restrict myocardial fibrosis and cardiac remodeling after MI and contribute to improved survival. Radionuclide imaging with technetium-99m–labeled Cy5.5 RGD imaging peptide (CRIP) targets myofibroblasts and indirectly allows monitoring of the extent of collagen deposition post-MI.MethodsCRIP was intravenously administered for gamma imaging after 4 weeks of MI in 63 Swiss-Webster mice and in 6 unmanipulated mice. Of 63 animals, 50 were treated with captopril (C), losartan (L), spironolactone (S) alone, or in combination (CL, SC, SL, and SCL), 8 mice received no treatment. Echocardiography was performed for assessment of cardiac remodeling. Hearts were characterized histopathologically for the presence of myofibroblasts and thick and thin collagen fiber deposition.ResultsAcute MI size was similar in all groups. The quantitative CRIP percent injected dose per gram uptake was greatest in the infarct area of untreated control mice (2.30 ± 0.14%) and decreased significantly in animals treated with 1 agent (C, L, or S; 1.71 ± 0.35%; p = 0.0002). The addition of 2 (CL, SC, or SL 1.31 ± 0.40%; p < 0.0001) or 3 agents (SCL; 1.16 ± 0.26%; p < 0.0001) demonstrated further reduction in tracer uptake. The decrease in echocardiographic left ventricular function, strain and rotation parameters, as well as histologically verified deposition of thin collagen fibers, was significantly reduced in treatment groups and correlated with CRIP uptake.ConclusionsRadiolabeled CRIP allows for the evaluation of the efficacy of neurohumoral antagonists after MI and reconfirms superiority of combination therapy. If proven clinically, molecular imaging of the myocardial healing process may help plan an optimal treatment for patients susceptible to heart failure

Outcomes of Patients with Asymptomatic Aortic Stenosis Followed Up in Heart Valve Clinics

Importance: The natural history and the management of patients with asymptomatic aortic stenosis (AS) have not been fully examined in the current era. Objective: To determine the clinical outcomes of patients with asymptomatic AS using data from the Heart Valve Clinic International Database. Design, Setting, and Participants: This registry was assembled by merging data from prospectively gathered institutional databases from 10 heart valve clinics in Europe, Canada, and the United States. Asymptomatic patients with an aortic valve area of 1.5 cm2 or less and preserved left ventricular ejection fraction (LVEF) greater than 50% at entry were considered for the present analysis. Data were collected from January 2001 to December 2014, and data were analyzed from January 2017 to July 2018. Main Outcomes and Measures: Natural history, need for aortic valve replacement (AVR), and survival of asymptomatic patients with moderate or severe AS at entry followed up in a heart valve clinic. Indications for AVR were based on current guideline recommendations. Results: Of the 1375 patients included in this analysis, 834 (60.7%) were male, and the mean (SD) age was 71 (13) years. A total of 861 patients (62.6%) had severe AS (aortic valve area less than 1.0 cm2). The mean (SD) overall survival during medical management (mean [SD] follow up, 27 [24] months) was 93% (1%), 86% (2%), and 75% (4%) at 2, 4, and 8 years, respectively. A total of 104 patients (7.6%) died under observation, including 57 patients (54.8%) from cardiovascular causes. The crude rate of sudden death was 0.65% over the duration of the study. A total of 542 patients (39.4%) underwent AVR, including 388 patients (71.6%) with severe AS at study entry and 154 (28.4%) with moderate AS at entry who progressed to severe AS. Those with severe AS at entry who underwent AVR did so at a mean (SD) of 14.4 (16.6) months and a median of 8.7 months. The mean (SD) 2-year and 4-year AVR-free survival rates for asymptomatic patients with severe AS at baseline were 54% (2%) and 32% (3%), respectively. In those undergoing AVR, the 30-day postprocedural mortality was 0.9%. In patients with severe AS at entry, peak aortic jet velocity (greater than 5 m/s) and LVEF (less than 60%) were associated with all-cause and cardiovascular mortality without AVR; these factors were also associated with postprocedural mortality in those patients with severe AS at baseline who underwent AVR (surgical AVR in 310 patients; transcatheter AVR in 78 patients). Conclusions and Relevance: In patients with asymptomatic AS followed up in heart valve centers, the risk of sudden death is low, and rates of overall survival are similar to those reported from previous series. Patients with severe AS at baseline and peak aortic jet velocity of 5.0 m/s or greater or LVEF less than 60% have increased risks of all-cause and cardiovascular mortality even after AVR. The potential benefit of early intervention should be considered in these high-risk patients

A new 2D-based method for myocardial velocity strain and strain rate quantification in a normal adult and paediatric population: assessment of reference values

<p>Abstract</p> <p>Background</p> <p>Recent advances in technology have provided the opportunity for off-line analysis of digital video-clips of two-dimensional (2-D) echocardiographic images.</p> <p>Commercially available software that follows the motion of cardiac structures during cardiac cycle computes both regional and global velocity, strain, and strain rate (SR).</p> <p>The present study aims to evaluate the clinical applicability of the software based on the tracking algorithm feature (studied for cardiology purposes) and to derive the reference values for longitudinal and circumferential strain and SR of the left ventricle in a normal population of children and young adults.</p> <p>Methods</p> <p>45 healthy volunteers (30 adults: 19 male, 11 female, mean age 37 ± 6 years; 15 children: 8 male, 7 female, mean age 8 ± 2 years) underwent transthoracic echocardiographic examination; 2D cine-loops recordings of apical 4-four 4-chamber (4C) and 2-chamber (2C) views and short axis views were stored for off-line analysis.</p> <p>Computer analyses were performed using specific software relying on the algorithm of optical flow analysis, specifically designed to track the endocardial border, installed on a Windows™ based computer workstation. Inter and intra-observer variability was assessed.</p> <p>Results</p> <p>The feasibility of measurements obtained with tissue tracking system was higher in apical view (100% for systolic events; 64% for diastolic events) than in short axis view (70% for systolic events; 52% for diastolic events). Longitudinal systolic velocity decreased from base to apex in all subjects (5.22 ± 1.01 vs. 1.20 ± 0.88; p < 0.0001). Longitudinal strain and SR significantly increased from base to apex in all subjects (-12.95 ± 6.79 vs. -14.87 ± 6.78; p = 0.002; -0.72 ± 0.39 vs. -0.94 ± 0.48, p = 0.0001, respectively). Similarly, circumferential strain and SR increased from base to apex (-21.32 ± 5.15 vs. -27.02 ± 5.88, p = 0.002; -1.51 ± 0.37 vs. -1.95 ± 0.57, p = 0.003, respectively).</p> <p>Values of global systolic SR, both longitudinal and circumferential, were significantly higher in children than in adults (-1.3 ± 0.2, vs. -1.11 ± 0.2, p = 0.006; -1.9 ± 0.6 vs. -1.6 ± 0.5, p = 0.0265, respectively). No significant differences in longitudinal and circumferential systolic velocities were identified for any segment when comparing adults with children.</p> <p>Conclusion</p> <p>This 2D based tissue tracking system used for computation is reliable and applicable in adults and children particularly for systolic events. Measured with this technology, we have established reference values for myocardial velocity, Strain and SR for both young adults and children.</p

Three-dimensional echocardiographic evaluation of aortic disorders with rotational multiplanar imaging: experimental and clinical studies

Transesophageal echocardiography has become a highly valuable method to assess aortic disorders. With this method, however, aortic disease has been visualized only in two-dimensional views. Advances in computer technology have introduced three-dimensional (3D) echocardiography as a developing modality in cardiac imaging. Previous efforts to obtain 3D reconstructions of the aorta, by various techniques, had limited clinical applicability. In this study we attempted to explore the feasibility and potential of 3D reconstructions of the aorta employing a widely used multiplane transesophageal imaging technique in an experimental setting and in patients. In the in vitro study, we created 35 lesions in 28 pig aortic trees (15 aortic dissections, five saccular aneurysms, five coarctations, five atheromas, and five clots within dissections). Suspending these specimens in a water bath, sequential two-dimensional images were acquired over a 180-degree rotation with a commercially available multiplane transesophageal probe and ultrasound system with a 3D software package. Data processing (digital reformation, interpolation, and segmentation) and 3D display were accomplished on an off-line computer system. 3D reconstructions were achieved and displayed in wire-frame, surface-rendered, and volume-rendered images. These 3D reconstructions corresponded well with the actual anatomic specimens in delineating the various pathologic findings. In patient studies, we collected a total of 36 studies in both adults and children with a mean age of 44.5 years (range 1 month to 82 years). In addition to normal aortas (n = 13), the spectrum of abnormalities studied included six atheromatous lesions, four aortic dissections, 10 coarctations, one aneurysm with a thrombus, and one dilated aortic root. We were able to accomplish volume-rendered 3D images depicting the aortic lesions in their true form that could be viewed in many different perspectives in all patients. We conclude that 3D echocardiography is able to display the aorta and aortic disease in a realistic manner. Although this modality still has limitations, further improvements in computer and ultrasound technology would strengthen 3D echocardiography as a clinically viable diagnostic tool, in the evaluation of aortic disorders

Connecting PhenoCam Sites with the ORNL DAAC MODIS Global Subsetting and Visualization Tool

The PhenoCam website (http://phenocam.unh.edu/) is tasked with acquiring, processing, and archiving web imagery from inexpensive webcams to be used for scientific studies of phenological processes. PhenoCam is currently archiving imagery from about 200 cameras mounted on towers, buildings, and other permanent structures, with a view across the top of the vegetation canopy. From this image data we extract time series of gcc (green chromatic coordinate) values, which contain a seasonal phenological signal for the local canopy. One goal of the PhenoCam project is to compare this no-altitude remote sensing data with space-borne remote sensing data. This is a common task faced by many low- and no-altitude observatories. Here we report on linking PhenoCam time series camera data (gcc time series) with MODIS Vegetation Index (EVI/NDVI) time series data using the Oak Ridge National Lab Distributed Active Archive Center (ORNL DAAC) MODIS Global Subsetting and Visualization Tool and the associated web services. By using a combination of ORNL DAAC web services, and by automated submission of processing requests, we provide easy access to comparable time-series from the two data sources. This should facilitate the development of models to extract transition dates from the time series data and the comparison of those dates between the two data sources

Myocardial contrast echocardiography for the detection of coronary artery stenosis : a prospective multicenter study in comparison with single-photon emission computed tomography.

The purpose of this study was to compare myocardial contrast echocardiography (MCE) with single-photon emission computed tomography (SPECT) for the detection of significant coronary artery disease (CAD) in patients with symptoms suggestive of CAD