Detection of Intraoperative Segmental Wall Motion Abnormalities by Transesophageal Echocardiography

In Response: We thank Dr. Young et al. for their careful review of our paper and their interesting questions. Our data can be analyzed in many ways to answer their key question, "What is the incremental value of additional cross-sections in the transverse and longitudinal views?" Three general alternatives are to: 1) consider each segmental wall motion abnormality (SWMA) as independent, 2) eliminate double counting of SWMAs detected in the same segment but in different cross-sections, and 3) count only the patients with SWMAs detected in cross-sections other than in the midpapillary transverse (MP-T) cross-section. We used the first alternative to report the results in our manuscript; of the 126 abnormal segments, 22 (17%) were detected in the MP-T cross-section, 60 (48%) were detected in the other transverse-plane cross-sections, and 44 (35%) were detected in the longitudinal-plane cross-sections. To eliminate double counting and use the second alternative, we offer a revised Table 3[1]. In this the revised Table 3 are listed in descending order according to the success rate of their acquisition, that is, the cross-sections successfully acquired in all patients are listed first; those acquired in the least patients are listed last. The MP-T cross-section was acquired in all patients, was assumed to be the basic monitoring cross-section, and is listed first. For all other cross-sections listed in the revised Table 3, the number of abnormal segments listed is less than that reported in our original manuscript because an abnormal segment is counted only once, i.e., if it were detected in any cross-section listed above in the table, that SWMA was not credited to any subsequent cross-section. Thus, the order in which the examination is performed affects the relative value of each cross-section. Using this revision, there are 91 abnormal segments: 22 (24%) detected in the MP-T cross-section, 44 (48%) in other transverse-plane cross-sections, and 25 (28%) in longitudinal-plane cross-sections. Finally, using the third alternative, we found 16 patients with SWMAs in the MP-T cross-section alone. Seven other patients were found to have SWMAs in other cross-sections of the transverse plane (not present in the MP-T cross-section), and five other patients had SWMAs detected in cross-sections of the longitudinal plane alone. Thus, the SWMAs were detected in 16 patients (57%) using the MP-T cross-section, in 7 patients (25%) using additional transverse-plane cross-sections, and in 5 patients (18%) in cross-sections of the longitudinal plane alone. As suggested correctly by Drs. Young et al., alternative analysis of our data provides an increase in the incremental value of the MP-T cross-section and a decrease in that of the longitudinal-plane cross-sections.Table 3: Incremental Value of Cross-Sections for the Detection of Segmental Wall Motion Abnormalities (Revised)In addition, we agree that regional wall-motion abnormalities may involve more than one segment of the left ventricle, but due to the existence of collateral vessels, we cannot know all the variants of blood supply to segments of the left ventricle [2]. Therefore, we did not make a distinction between regional and segmental wall motion abnormalities. In summary, in our original article, we reported the independent value of each cross-section, including the success of acquisition, the adequacy of endocardial resolution, and the detection of SWMAs. The incremental value of each cross-section is limited by the ability to acquire each cross-section in each patient, and, importantly, depends on the order in which the echocardiographic examination is performed. We appreciate the opportunity to respond to the excellent questions raised by Dr. Young et al. Kathryn Rouine-Rapp, MD Michael K. Cahalan, MD Department of Anesthesia; School of Medicine; University of California; San Francisco, CA 94143-0648