A 62 year old man with previous myocardial infarction, an occluded right coronary artery and a 90% stenosis of the left anterior descending coronary artery underwent angioplasty with the support of ...coronary venous retroperfusion of arterial blood during the procedure. In two of four angioplasty balloon dilations of the left anterior descending coronary artery, synchronized diastolic retroperfusion of the coronary veins with arterial blood was applied to protect the severely dysfunctioning myocardium from additional ischemia. Two-dimensional echocardiography was used to monitor and quantitate alterations in left ventricular function.
Retroperfusion of arterial blood resulted in immediate improvement in ischemic zone wall motion despite the totally occluded artery during balloon dilation. Echocardiographic images recorded after angioplasty showed a marked improvement in contraction of the previously dyskinetic segments, with changes similar to those seen during balloon dilations with synchronized diastolic coronary venous retroperfusion. Thus, in this patient, viability of chronically dysfunctioning myocardium could be demonstrated by the improvement in regional wall motion during retroperfusion.
This technique could eventually be of value to elucidate the anatomic location of viable myocardium while maintaining adequate left ventricular systolic function during coronary artery interventions in the catheterization laboratory.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This study examines the effects of brief periods of ischemia on average and cardiac cycle-dependent variation of regional ultrasonic backscatter paralleled with changes in regional myocardial ...contraction, and to what extent these changes could be reversed by synchronized coronary venous retroperfusion. In five closed-chest dogs, the left anterior descending coronary artery was occluded on four occasions for a 2-minute period and retroperfusion was applied randomly to two of the coronary occlusions. Complete functional recovery was allowed between the occlusions. Two-dimensional echocardiographic images were obtained before and at the peak of the 2-minute occlusion period. Regional myocardial contraction as measured by fractional area change and systolic wall thickening during untreated occlusions decreased from 33.9 +/- 14.0% to -0.15 +/- 6.2%, and from 22.0 +/- 1.8% to -17.9 +/- 2.2%, whereas during retroperfusion-treated occlusions it changed from 37.4 +/- 8.5% to only 23.4 +/- 11.2% (p less than 0.005 versus baseline), and from 24.1 +/- 2.8% to only 12.7 +/- 2.0% (p less than 0.005 versus baseline), corresponding to a preservation of 62% and 52% of baseline regional contraction, respectively. Average regional gray level (arbitrary units) during untreated coronary occlusions exhibited a significant increase in the ischemic regions, from 5.6 +/- 2.7 at baseline to 11.5 +/- 4.4 during occlusion (p less than 0.005); during retroperfusion-treated occlusions, average gray level increased from 4.7 +/- 3.6 to only 6.3 +/- 3.6 (NS). Untreated coronary artery occlusions resulted in a systolic increase in gray level in the ischemic region, followed by a diastolic decrease.
Measurement errors that may interfere with quantitation by the new myocardial contrast two-dimensional echocardiographic technique were examined in a simplified in vitro model consisting of a 50 cc ...blood-filled balloon with supplemental controlled injection of 0.2 to 2.6 cc of sonicated dextrose 70%. The blood-contrast mixture in the balloon volume was imaged with two-dimensional echocardiography and discrete regions were studied for both magnitude and time course of echo intensities. Preliminary evidence indicates that a regional contrast echo intensity measurement is significantly modified by contrast-related ultrasound attenuation in intervening regions and by the amount and mode of contrast material injection. Thus, injection of 1.2 cc contrast material resulted in substantially higher peak echo intensity and a more rapid decay than injection of 0.8 or 0.6 cc. These measurements were also found to be influenced by the echographic system signal processing and time-gain compensation which contribute to nonlinear and unevenly compensated image distribution of echo amplitudes. Other factors are discussed, including transducer-related image resolution and image texture, contrast agent bubble size and persistence and computer methods for standardized selection of region of interest and analysis of the regional contrast intensity decay curve.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
The characterization of the Advanced LIGO detectors in the second and third observing runs has increased the sensitivity of the instruments, allowing for a higher number of detectable ...gravitational-wave signals, and provided confirmation of all observed gravitational-wave events. In this work, we present the methods used to characterize the LIGO detectors and curate the publicly available datasets, including the LIGO strain data and data quality products. We describe the essential role of these datasets in LIGO–Virgo Collaboration analyses of gravitational-waves from both transient and persistent sources and include details on the provenance of these datasets in order to support analyses of LIGO data by the broader community. Finally, we explain anticipated changes in the role of detector characterization and current efforts to prepare for the high rate of gravitational-wave alerts and events in future observing runs.
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