Analyses of regional left ventricular systolic wall motion or thickening overestimate infarct size. We used quantitative two-dimensional echocardiographic analysis of systolic thickening and contrast two-dimensional echocardiography to evaluate causes for that overestimation. The following possibilities were considered: (1) "tethering," defined as dysfunction of contrast-enhancing myocardium adjacent to ischemic or contrast-negative regions, and (2) the role of standard center of mass analysis algorithms, which may overestimate wall motion abnormalities because of the axis shift produced by simultaneous systolic expansion of the ischemic segment and systolic contraction of the nonischemic segment. In the short-axis view in 12 animals, the echo contrast defect (ECD) occupied 32 + 7% of the left ventricular circumference. Extent of dysfunction by the center of mass analysis was 39 + 5% of the left ventricular circumference and correlation with ECD size was .68 (SEE = 5.2%). Thus 8 -+-6% of the circumference of the left ventricle was assessed to be dysfunctional yet enhanced with contrast. Tethering accounted for only half of this (4 + 4% of left ventricular circumference) and involved less than 1 cm on either side of the ECD. The remaining overestimation by the center of mass analysis correlated significantly (r = .89, p < .01) with the amount of systolic expansion of the ECD. This expansion of the ECD (increase in angle subtended by the ECD of 11 ± 8%) was produced by the systolic shift in the center of mass toward the dysfunctional segment from contraction of the opposite, nonischemic segment, since true systolic lengthening of the ischemic (contrast-negative) segment was minimal (increase of only 3 + 5%; p < .01 vs increase in angle subtended by ECD). When systolic function was analyzed independent of a center of mass with the ECD as an internal reference, the correlation between extent of dysfunction and ECD size improved to .84 (SEE = 3.8%). In conclusion, two-dimensional echocardiography has exaggerated the importance of tethering because of flaws in standard analysis algorithms. Tethering does lead to an unavoidable overestimation of infarct size, but the amount of myocardium involved is small and relatively predictable. The remainder of the overestimation of infarct size by two-dimensional echocardiography is critically dependent on systolic function of the opposite, nonischemic wall. Since this is variable, it accounts in large part for the suboptimal correlation between infarct size and extent of dysfunction by standard two-dimensional echocardiographic analyses. Circulation 73, No. 6, 1360-1368, 1986 TWO-DIMENSIONAL echocardiography could in theory be an ideal technique for studying the effects of interventions to limit infarct size. However, two-dimensional echocardiographic analyses of either regional left ventricular systolic wall motion or thickening consistently overestimate infarct size. '-13
Contrast echocardiography can predict pathologic area at risk during acute coronary occlusion. In this study we evaluated (1) whether the intensity and timing of contrast appearance in ischemic regions can provide a quantitative measure of residual myocardial perfusion, and (2) whether changes in these parameters observed after serial injections reflect changes in blood flow to acutely ischemic tissue. Supra-aortic hydrogen peroxide contrast echocardiography was performed in 12 consecutive dogs at 1, 20, and 120 min after acute circumflex coronary occlusion. Contrast enhancement was determined qualitatively with a segmental four-point scoring system based on the appearance time and peak perceived intensity of contrast enhancement and quantitatively with a computer algorithm designed to reflect these parameters. Comparison was made in each segment to concomitant radioactive microsphere blood flow. Qualitative scoring related systematically to normalized segmental blood flow (3 + = 93%; 2 + = 61 %; 1 + = 32%; 0 = 18%; p < .01 for each vs adjacent value), as did quantitative analysis including all segments (r = .78; p < .01) and isolated to the ischemic region (flow = 1.13 intensity change + 6.8%; r = .83, p < .001). Changes in microsphere flow in ischemic regions between sequential observations were correlated with changes in qualitative score (r = .88, p < .001) and results of quantitative analysis (r = 0.70, p < .01). The amount of contrast enhancement can provide quantitative information about residual myocardial blood flow in ischemic regions and can also be used to track changing patterns of flow in vivo after acute coronary occlusion. Circulation 72, No. 5, 1115No. 5, -1124No. 5, , 1985 THE SUPRA-AORTIC INJECTION of microbubblecontaining solutions during echocardiographic imaging of the heart results in an intense increase in myocardial contrast in regions that receive normal blood flow. Regions that are severely malperfused do not enhance and can be seen as a contrast defect. Studies in our laboratory and others indicate that the size of this contrast defect accurately predicts the size in vivo of the region that is at risk of infarction after acute coronary occlusion.'-5 Contrast analyses have not previously been evaluated for their ability to quantify the amount, rather than the presence or absence, of flow within the ischemic region.During our previous studies of supra-aortic hydrogen peroxide contrast echocardiography in canine in-
Acute myocardial infarction progresses radially from endocardium to epicardium within the ischemic area. The amount of progression is highly variable, but depends largely on the transmural distribution of myocardial blood flow. Recent contrast echocardiographic observations indicate that slowly appearing low levels of contrast enhancement are often seen in the ischemic region, particularly in the epicardial level, and that ischemic regions which show these low levels of contrast have significantly more blood flow than those that do not. This study was designed to determine whether the transmural distribution of this delayed contrast enhancement can sufficiently discriminate between regions of high and low flow to serve as an in vivo predictor of the transmural extent of acute infarction. Twenty-four dogs had acute circumflex coronary ligation which was maintained for 6 hours. Contrast echocardiographic studies were performed at the level of the mitral chordae 2 hours after occlusion using a dilute hydrogen peroxide and blood solution as a contrast agent. Comparison was made with the pathologic infarct measured by triphenyltetrazolium chloride staining. The mean transmural extent of infarction ranged from 0 to 89% and was predicted in vivo by the transmural extent of the delayed contrast defect (r = 0.92; infarction [percent transmural] = 0.74 contrast [percent transmural] + 11%; SEE = 10%). Reproducibility for the transmural extent of delayed contrast defects was good (r = 0.89 to 0.98.) These data further support the concept that the transmural distribution of delayed contrast enhancement parallels blood flow and indicate that the mean transmural extent of acute infarction can be predicted in vivo 2 hours after coronary occlusion from the residual contrast defect.
BACKGROUND.Sentinel lymph node (SN) biopsy is standard for breast cancer staging, but SN dye gradients and their significance have never been characterized. If predictive of SN metastasis location, their use for focused pathology examination might improve intraoperative imprint cytology sensitivity.METHODS.This prospective trial enrolled clinically lymph node‐negative patients with invasive breast cancer not undergoing neoadjuvant chemotherapy. Surgeons marked SN gradients at their bluest end. Nodal halves were examined separately by imprint cytology, and the marked SN half was correlated to metastasis location. Demographic, pathologic, and prognostic features were recorded.RESULTS.Mean patient age and tumor size for the 102 patients was 59.6 years and 2.2 cm, respectively. Of 169 SNs, 159 (94.1%) had dye gradients, which varied by tumor quadrant, but not by histology, diagnosis method, grade, or stage. Among 41 marked SNs with metastases, 92.7% were present in the halves marked by the surgeon. Fourteen were confined to 1 nodal half, with 11 on the marked side and 3 on the unmarked side (P = .029). Metastases were smaller when confined to 1 versus both SN halves (0.14 vs 0.75 cm; P = .005), and smaller (0.87 vs 0.13 cm; P < .0001) when missed intraoperatively.CONCLUSIONS.Dye gradients occur in most SNs and predict metastasis location. The smallest metastases are hardest to detect intraoperatively and are usually confined to the marked SN half. This suggests that marking an SN's bluest half warrants further study to explore whether its correlation to metastasis location may be exploited to focus pathologic examination and decrease the reoperative axillary dissection rate. Cancer 2008. © 2008 American Cancer Society.
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