Peter M. Sapin

TRANSESOPHAGEAL ECHOCARDIOGRAPHY IN THE DIAGNOSIS OF TRAUMATIC RUPTURE OF THE AORTA

Background Rupture of the aorta is a major cause of death after motor vehicle accidents. Survival depends on early diagnosis, and emergency aortography is the standard imaging method. Although transesophageal echocardiography is noninvasive and can provide high-resolution images of the aorta, information about its value in patients with trauma is limited. We conducted this study to assess prospectively the value of transesophageal echocardiography in the emergency evaluation of patients at risk for aortic injury. Methods Transesophageal echocardiography of the aorta was attempted in 101 patients admitted to the emergency room with a diagnosis of possible traumatic rupture of the aorta. Echocardiography and aortography personnel were notified simultaneously of the arrival of the patient, and the two tests were performed sequentially by operators who were blinded to the results of the other test. The sensitivity and specificity of transesophageal echocardiography were calculated on the basis of the results ...

Three-dimensional echocardiographic measurement of left ventricular volume in vitro: Comparison with two-dimensional echocardiography and cineventriculography

OBJECTIVESnThis study was designed to compare three-dimensional echocardiography, two-dimensional echocardiography and cineventriculography for the purpose of measuring left ventricular volume in vitro.nnnBACKGROUNDnThree-dimensional echocardiographic systems have been shown to be highly accurate in measuring the volumes of balloon phantoms. However, three-dimensional techniques have not been compared with standard two-dimensional echocardiography in vitro or with cineventriculography, the clinical standard for left ventricular volume measurement.nnnMETHODSnExcised porcine hearts were prepared with an internal latex sheath that could be filled and maintained with a known (true) volume of liquid. Each heart was then imaged by cineventriculography, standard two-dimensional echocardiography and three-dimensional echocardiography. Left ventricular volumes were calculated from 15 hearts at 25 volumes ranging from 50 to 280 ml by the following methods: 1) biplane cineventriculography using the area-length method; 2) two-dimensional echocardiography by the apical biplane method using a summation of discs algorithm in 15 cases and the single-plane, four-chamber method using a summation of discs algorithm in 10 cases; and 3) three-dimensional echocardiography using a polyhedral surface reconstruction volume computation algorithm based on multiple nonparallel, nonevenly spaced short-axis cross sections.nnnRESULTSnResults were compared with true volume, and a nonparametric analysis of variance was performed. Both measurement bias (systematic error) and imprecision (random error) were assessed. All methods tended to underestimate the true volume (two-dimensional echocardiography -6.1 +/- 17.6%, three-dimensional echocardiography -4.7 +/- 5.0% and biplane cineventriculography -3.9 +/- 8.2%), although differences were not significant. Although there was a significant correlation between the magnitude of measurement bias and the size of the volume being measured for two-dimensional echocardiography and cineventriculography, the bias of three-dimensional echocardiography was fairly constant over the range of volumes. When bias was accounted for, two-dimensional echocardiography was significantly less precise than cineventriculography and three-dimensional echocardiography in terms of percent error (15.3 +/- 11.9%, 5.6 +/- 5.7% and 3.9 +/- 3.4%, respectively).nnnCONCLUSIONSnThree-dimensional echocardiography using a polyhedral surface reconstruction algorithm for volume computation provides accuracy comparable to that of biplane cineventriculography in this in vitro model. Standard two-dimensional echocardiographic volume computation is significantly less accurate than the other two methods.

Use of transesophageal echocardiography in the evaluation of traumatic aortic injury.

Indications for aortography following blunt chest trauma are broad and ill-defined. This study prospectively assessed the role of transesophageal echocardiography (TEE) in the evaluation of suspected aortic injury. We used both TEE and aortography to evaluate 69 patients with suspected thoracic aortic injury. The studies were performed and interpreted by staff radiologists and cardiologists. The mean study time for TEE was 27 minutes, whereas the mean study time for aortography was 76 minutes (p < 0.05). No complications occurred with either procedure. Both TEE and aortography revealed no evidence of aortic injury in 61 patients. There was one false-positive aortogram. TEE identified seven aortic injuries; four were confirmed by aortography. One patient underwent thoracotomy and aortic repair based on TEE findings alone. Aortograms yielded false-negative results for two patients; one injury was confirmed at thoracotomy, the other at autopsy. TEE accurately predicted the presence or absence of aortic injury in each case, for a diagnostic sensitivity and specificity of 100%. TEE can be performed safely and efficiently on the multiple-injury patient. We conclude that TEE is useful in the evaluation of suspected aortic injury.

Further experience with transesophageal echocardiography in the evaluation of thoracic aortic injury

This prospective study sought to further define the role of transesophageal echocardiography (TEE) in diagnosing thoracic aortic injury. We performed TEE, aortography, or both on 160 consecutive patients suspected of having blunt thoracic aortic injury: TEE correctly identified 14 aortic injuries, of which five were confirmed by aortography, seven at thoracotomy, and two at autopsy. The TEE results were suggestive of but not diagnostic for injury in two additional patients with proven aortic injury, and TEE was otherwise 100% sensitive and specific for aortic injury. Aortograms yielded one false positive result and four false negative results, for a sensitivity of 73% and a specificity of 99%. We conclude that TEE is a rapid, safe, and accurate bedside method for evaluating the heart and thoracic aorta for blunt trauma. Negative or positive TEE results obviate the need for aortography. We recommend that aortography be used when TEE results are equivocal, when TEE is not tolerated or contraindicated, or when other suspected vascular injuries require evaluation by arteriography.

Three-dimensional echocardiography: Limitations of apical biplane imaging for measurement of left ventricular volume

A new three-dimensional echocardiographic system creates a line of intersection display to allow precise and known positioning of echocardiographic images. Our purpose was to determine whether use of the line-of-intersection display will improve positioning of the apical four-chamber and apical two-chamber views and thereby improve the agreement between estimates of left ventricular volume by apical biplane echocardiography and cineventriculography. Unguided and line of intersection-guided apical biplane views were obtained in 31 patients immediately before cardiac catheterization and single-plane cineventriculography. In 15 patients the line-of-intersection display was used to measure the position of the image plane in studies of unguided and guided methods. Linear regression and limits of agreement analysis were used to assess the agreement between cineventriculographic volumes and echocardiographic volumes determined from each set of images. The Wilcoxon test was used to compare guided and unguided image positioning. The line-of-intersection display improved four-chamber and two-chamber view positioning closer to the center of the ventricle and rotation closer to orthogonal positioning. Guided-image positioning was not able to correct displacement of the ultrasound beam anterior to the ventricular apex without deterioration of image quality in most patients. Despite improvements in image plane positioning, the agreement between echocardiographic and cineventriculographic volumes was unchanged. For end-diastole views, the unguided images had an r value = 0.84, standard error of the estimate of +/- 23.0 cc, and limits of agreement of +/- 62.4 cc. Corresponding values for the guided images at end diastole were r = 0.85, standard error of the estimate of +/- 22.9 cc, and limits of agreement of +/- 60.8 cc. At end systole the unguided results were r = 0.91, standard error of the estimate of 16.8 cc, and limits of agreement of +/- 52.2 cc. The line-of-intersection guiding of image plane positioning can improve apical image positioning but does not improve the agreement between apical biplane echocardiographic and cineventriculographic left ventricular volumes. The optimal apical imaging window is frequently occluded by the rib cage, resulting in a decrease in image quality. This reduction of image quality, combined with assumptions of left ventricular geometry, limit the accuracy of estimates of left ventricular volume from apical biplane echocardiography.

Three-dimensional Echocardiography

Conventional two-dimensional echocardiography is limited in its ability to illustrate complex cardiac structural relationships arid by the need for assumptions about image plane positioning and ventricular geometry when quantitation is performed. Three-dimensional echocardiography, the coupling of cardiac ultrasound images with a system that locates the images in space with reference to an external coordinate system, can address these limitations. Three dimensional systems currently in use have demonstrated the ability to provide unique views of the heart; for example, a “surgeons view” of the mitral valve from the left atrium. Three-dimensional echocardiography is also proving to be more accurate than conventional two-dimensional echocardiography for the measurement of left ventricular volume, mass, and ejection fraction and shows promise for the measurement of these parameters of right ventricular structure and function. Three-dimensional echocardiography will be increasingly clinically applicable, because it provides new and improved means of noninvasively visualizing and quantitating cardiac structure and function.

933-96 LV Mass Determination by 3D Echocardiography: Initial Clinical Experience and Comparison to Magnetic Resonance Imaging in Patients with Abnormal Ventricular Geometry

Measurement of LV mass and its regression is important in dilated and congenitally deformed ventricles as well as in those with normal shape and concentric hypertrophy. Conventional echo methods for mass estimation use geometric and image plane positioning assumptions that may be invalid in patients with abnormally shaped ventricles. 3D echo eliminates these assumptions and has been previously validated for LV mass determination in normally shaped ventricles (rxa0=xa00.93, SEExa0=xa09–11 g). In the same study Penn convention and 2D echo methods had standard errors greater than two times larger than 3D echo. Purpose To compare LV mass determination by 3D echo and MRI in patients with abnormal ventricular shape. Methods 30 patients underwent 3D echo and short-axis gradient reversal MRI within 6 hours. 3D echo data sets of 8-10 short axis, non-parallel, non-intersecting short axis crosssections were obtained using an acoustic spatial locater and a line of intersection display for guidance. End-diastolic image data sets were obtained, boundaries were traced manually and mass computed. Etiologies of abnormal ventricular shape included ischemic, idiopathic, congenital, valvular and alcoholic cardiac disease. Results were compared by linear regression and limits of agreement analysis. Results Linear Regression: Range: 86.3-400.3 g; Meanxa0=xa0205.7xa0±xa082.8 rxa0=xa00.82; SEExa0=xa034.9 g; Pxa0lxa00.001 3D ECHOxa0=xa00.59 MRIxa0+xa072.8 g Limits of Agreement: Bias (mean of differences)xa0=xa0-11.4 g Limits (2 SD of differences)xa0=xa096.4 g Conclusions Left ventricular mass determination by 3D echo is clinically feasible. Initial clinical experience in unselected patients with abnormal ventricles demonstrates good correlation and standard error, small bias and acceptable limits of agreement with MRI. 3D echo offers a new means for clinical assessment of LV mass