Echo-Doppler in the management of acute non-Q wave myocardial infarction.
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Echocardiography, Doppler↗
Biomedical subjects
S C Siu
Publications and source records attributed to S C Siu.
Intra-aortic balloon counterpulsation support in the high-risk cardiac patient undergoing urgent noncardiac surgery.
Patients with a recent myocardial infarction, congestive heart failure, sever angina, or uncorrected multivessel coronary artery disease are at increased risk of cardiac complications after major noncardiac surgery. Although invasive hemodynamic monitoring and preoperative optimization of cardiac status may lead to some reduction in the rate of perioperative cardiac events, the mortality from such events remains high. We report our experience with the use of perioperative intra-aortic balloon counterpulsation in eight patients with unstable coronary syndromes or severe coronary artery disease who underwent urgent noncardiac surgery. There were no perioperative cardiac events while the intra-aortic balloon pump (IABP) was in place. There were two postoperative cardiac events (non-fatal myocardial infarction, congestive heart failure) in the first postoperative week after the IABP was removed. One patient required emergent femoral thrombectomy as a result of intra-aortic balloon counterpulsation and subsequently died of a gastrointestinal hemorrhage. Intra-aortic balloon counterpulsation should be considered as an adjunct to maintain hemodynamic stability for the high-risk cardiac patient about to undergo urgent or emergent noncardiac surgery.
Aged↗
Coronary artery disease in the octogenarian: angiographic spectrum and suitability for revascularization.
The angiographic findings of 84 consecutive octogenarians presenting with symptoms of coronary artery disease (CAD) were examined to determine the extent of CAD as well as suitability for both coronary artery bypass grafting (CABG) and percutaneous transluminal coronary angioplasty (PTCA). The frequency of 0-, 1-, 2-, and 3-vessel and left main CAD was 7, 14, 21, 57 and 13%, respectively. Based on angiographic criteria, 69 of 78 patients (88%) with significant CAD had suitable coronary anatomy for CABG. Only 24 patients (31%) had coronary anatomy amenable to PTCA. CABG was performed in 19 patients with an operative mortality of 16% and major complication rate of 37%. PTCA was performed in 12 patients with a clinical success rate of 83%, mortality of 8% and major complication rate of 8%. It is concluded that in octogenarians with CAD, cardiac catheterization will often reveal coronary anatomy that is suitable for CABG but less suitable for PTCA. The morbidity and mortality associated with these interventions are high.
Aged↗
Adrenal insufficiency from bilateral adrenal hemorrhage.
Bilateral adrenal hemorrhage is a rare cause of adrenal insufficiency in adults. Because of the nonspecific manifestations of adrenal insufficiency, antemortem diagnosis is difficult. Serial computed tomographic scans of the abdomen are a valuable adjunct in confirming the diagnosis of bilateral adrenal hemorrhage, which manifests as round or oval adrenal masses of high density that subsequently decrease in both size and density. The diagnosis should be suspected in any complex highly stressful illness, in the postoperative period, or in the presence of a coagulopathy in conjunction with hypotension, fever, or electrolyte disturbances. Herein we describe five patients in whom the computed tomographic scans suggested or confirmed the presence of bilateral adrenal hemorrhage. In three of the five patients, the presence of a circulating lupus anticoagulant was demonstrated. Once the diagnosis of adrenal hemorrhage is suspected, steroid replacement therapy should be initiated promptly.
Adrenal Gland Diseases↗
Automated assessment of ventricular volume and function by echocardiography: validation of automated border detection.
To determine the utility of a new on-line echocardiographic automated border detection (ABD) algorithm in assessing ventricular volume and ejection fraction, an optimal model was studied. This open-chest canine model allowed continuous measurement of actual left ventricular volume. In four dogs, true end-systolic and end-diastolic volume and ejection fraction were compared with those obtained by two-dimensional echocardiography with an automated method calculated from a border detection algorithm to define left ventricular endocardium and the single-plane Simpson method to calculate volume. Left ventricular volumes that used manual, off-line tracings of the left ventricle by two-dimensional echocardiograms and the single-plane Simpson method were compared. The automated echocardiographic volumes correlated with true volumes (y = 0.7x + 8.9; standard error of the estimate = 13.5 cc; r = 0.81). A significant mean underestimation of 11 +/- 15 cc was noted (p < 0.0001). Volumes obtained from the manual tracings of left ventricular endocardial contours also correlated well with true volumes (y = 0.89x + 4; standard error of the estimate = 6.7 cc; r = 0.96). However, the 3 +/- 7 underestimation was significantly lower than the error of the ABD method (p = 0.00005). Both on-line ABD and off-line ejection fractions correlated well with true ejection fractions (r = 0.94 and 0.96, respectively). There was no statistically significant difference between the mean errors of the ABD or manually derived ejection fractions. In the setting of optimal left ventricular imaging, the on-line and rapid features of this automated method make it potentially useful for quickly obtaining left ventricular volumes and ejection fraction.
Algorithms↗
Three-dimensional echocardiographic reconstruction of right ventricular volume: in vitro comparison with two-dimensional methods.
Two-dimensional echocardiographic measures of right ventricular volume are limited by the asymmetric and crescentic shape of that ventricle and the difficulty in obtaining standardized views. We have developed a three-dimensional echocardiographic system that automatically integrates images and positional data and calculates right ventricular volume without the need for geometric assumptions or standardized views and a surfacing algorithm that takes advantage of the full three-dimensional data set. The accuracy of this system was studied and compared with two-dimensional methods in 12 gel-filled excised human right ventricles (18 to 74 ml). Volumes calculated by three-dimensional echocardiography correlated well with actual values (r = 0.99) and agreed more closely with them than did those obtained by two-dimensional methods (p < 0.02).
Algorithms↗
Three-dimensional echocardiography: the influence of number of component images on accuracy of left ventricular volume quantitation.
One approach to three-dimensional echocardiography is to reconstruct the surface of cardiac structures from two-dimensional images positioned in three-dimensional space. This approach has yielded accurate measures; however, the relationship between the number of nonparallel images used in three-dimensional echocardiographic reconstruction to the accuracy of the volume calculated has not been determined. With a canine model in which instantaneous left ventricular volume could be measured in vivo, images were obtained from intersecting long- and short-axis scans and stored with their spatial coordinates. The left ventricle was reconstructed and its volume calculated. The difference between three-dimensional echocardiographic and true volume was determined in 84 different cavitary volumes (4 to 85 ml). In each case, long- and short-axis images were deleted serially from the original data set (maximum of 27) until there were only three images left in the reconstruction. After each set of deletions, left ventricular volume was recalculated with the remaining images. Three-dimensional echocardiography accurately quantified ventricular volume with eight to 12 intersecting images, with a mean error of less than 1 ml and an SD of 5 ml. With a reduction of component images below eight, there were progressive increases in both absolute and mean percentage error. Accurate assessment of stroke volume and ejection fraction in this beating heart model also required eight to 12 images. Left ventricular volume and systolic function can be quantitated by three-dimensional echocardiography with as few as eight to 12 intersecting or nonparallel images.
Analysis of Variance↗
Congenital heart disease in pregnancy.
Care of pregnant patients with congenital heart disease requires understanding of the specific congenital defect, the nature of previous surgical correction, and the residua and sequelae. General risks and principles can be adduced in management decisions. In addition, lesion- and patient-specific details are important. There are only a few conditions that place patients at a high enough risk to advise that pregnancy be avoided under all circumstances (pulmonary vascular obstructive disease, Marfan syndrome with dilated aortic root, severe aortic stenosis, and severe systemic ventricular dysfunction). Preconception counseling, optimization of status, and meticulous multidisciplinary management during pregnancy and the postpartum period will improve outcomes.
Counseling↗