Frequency and importance of postprandial blood pressure reduction in elderly nursing-home patients. Ann Intern Med 1991;115:865– 870. 5. Aronow WS, Ahn C. Association of postprandial hypotension with incidence of falls, syncope, coronary events, stroke, and total mortality at 29-month fol- low-up in 499 older nursing home residents. J Am Geriatr Soc 1997;45:1051– 1053. 6. Jansen RWMM, Lipsitz LA. Postprandial hypotension: epidemiology, patho- physiology and clinical management. Ann Intern Med 1995;122:286 –295. 7. Puvi-Rajasingham S, Wijeyekoon B, Natarajan P, Mathias CJ. Systemic and regional (including superior mesenteric) haemodynamic responses during supine exercise while fasted and fed in normal man. Clin Autonom Res 1997;7:149 –154. 8. Lipsitz LA, Ryan SM, Parker JA, Freeman R, Wei JY, Goldberger AL. Hemodynamic and autonomic nervous system responses to mixed meal ingestion in healthy young and old subjects and dysautonomic patients with postprandial hypotension. Circulation 1993;87:391– 400. 9. Ryan SM, Goldberger AL, Ruthazer R, Meitus J, LA Lipsitz. Spectral analysis of heart rate dynamics in elderly persons with postprandial hypotension. Am J Cardiol 1992;69:201–205. 10. Rowell LB. Human Cardiovascular Control. New York:Oxford University Press,1986:172–175; 204 –254. 11. Levy WC, Cerqueira MD, Harp GD, Johannessen KA, Abrass AB, Schwartz RS, Stratton JR. Effects of endurance exercise training on heart rate variability at rest in healthy young and older men. Am J Cardiol 1998;82:1236 –1241. Effect of Harmonic Imaging Without Contrast on Image Quality of Transesophageal Echocardiography Guido Rocchi, MD, Nico de Jong, PhD, Tjebbe W. Galema, MD, Jaroslaw D. Kasprzak, MD, PhD, and Folkert J. Ten Cate, MD, PhD H armonic imaging (HI) has been developed to improve the potential of contrast echocardiogra- phy. 1,2 It exploits the fact that microbubbles can res- onate when hit by ultrasound producing harmonics as multiples of transmitted frequency. 3–5 If the ultra- sound machine is tuned to receive a second harmonic frequency selectively, it can differentiate contrast from tissue. 6 However, baseline imaging is not deleted completely, because of nonlinear backscatter proper- ties of tissue. 7,8 This allows one to use harmonic imaging without contrast agents; this modality has been called tissue HI or native HI. Recent transtho- racic echo studies have shown the ability of tissue HI to improve endocardial border delineation. 9 –11 No previous study has been performed to assess the role of tissue HI during transesophageal echocardiography (TEE). Usually, TEE shows high-quality images, but at several occasions, as during cardiac surgery when the heart is dislocated from its normal position, image quality can be suboptimal. We developed a prototype transesophageal transducer that is able to obtain HI, and compared it with TEE image quality of harmonic and fundamental (conventional) imaging. The study was performed in the operating room during coronary artery bypass surgery (CABG). ••• Fourteen consecutive patients (mean age 60 6 8 years) referred for CABG were enrolled in the study. Transesophageal echocardiograms in both harmonic and fundamental modes were performed before and immediately after CABG in the operating room. The second acquisition was performed just after termina- tion of cardiopulmonary bypass pump to evaluate possible new wall motion abnormalities before its removal. A prototype transesophageal monoplane transducer interfaced with a Vingmed System Five ultrasound machine (Vingmed, Oslo, Norway) was used for all studies. Transgastric short-axis and esoph- ageal 4-chamber views were obtained in all patients. Fundamental images were obtained using a 4.4-MHz transmitted frequency, whereas for the harmonic mode the transducer transmitted at 2.9 MHz and re- ceived at 5.8 MHz. The 64-element broad-band trans- ducer received wide band in fundamental and small band in the second harmonic mode. Mechanical index was set at 1.0. Imaging was optimized by increasing dynamic range or by adjusting overall gain. Dynamic range was set at .60 dB in all cases. In 5 patients an additional second transducer with a higher fundamen- tal frequency (5.7 MHz) was tested after CABG to compare HI with fundamental imaging obtained by a commercial probe (Vingmed). Two experienced ob- servers, blinded for the acquisition method used, scored each echocardiogram for visualization of en- docardial borders. Visibility of endocardium was de- fined segment by segment using the following score: 0 5 not visible; 1 5 incomplete visualization during the all cardiac cycle; 2 5 incomplete visualization during part of the cardiac cycle; and 3 5 complete visualization. Wall motion was scored in a 4-grade model: 1 indicating normal wall motion, 2 hypokine- sia, 3 akinesia, and 4 dyskinesia. Inter- and intraobserver variability for visibility of endocardial borders was scored by 2 independent ob- servers and 30 days later by the first observer. Both observers were blinded for the acquisition method used. Kappa coefficients were calculated using a SAS system (SAS Institute, Cary, North Carolina) A k coefficient of .0.4, .0.6, and .0.8 indicated fair, good, and excellent agreement, respectively. Data are presented as mean 6 1 SD. Differences between fun- damental and harmonic score were evaluated by anal- ysis of variance for repeated measures or by paired Student’s t test when appropriate. A p value ,0.05 was considered significant. In all, 168 segments (12 segments 3 14 patients) were scored at both harmonic and fundamental imag- From the Heartcentre, Erasmus University, Rotterdam, The Nether- lands. Dr. Rocchi was supported by the Institute of Cardiology, Univer- sity of Bologna, Italy. Dr. Kasprzak was supported by an educational grant of the European Society of Cardiology, Nice, France. Dr. Ten Cate’s address is: Department of Cardiology, ZuiderZiekenhuis, Groene Hilledijk 315, 3075EA Rotterdam, The Netherlands. E-mail: f.ten.cate@zuiderziekenhuis.nl. Manuscript received February 1, 1999; revised manuscript received June 14, 1999, and accepted June 15. 1132 ©1999 by Excerpta Medica, Inc. All rights reserved. 0002-9149/99/$–see front matter The American Journal of Cardiology Vol. 84 November 1, 1999 PII S0002-9149(99)00521-4