title: Is left ventricular diastolic thickening documented during dobutamine and pacing stress echocardiography related to myocardial ischemia? An animal model study.
abstract: Transient increase in diastolic wall thickness (pseudohypertrophy) during pacing stress echocardiography has been reported in normal myocardium. To evaluate the occurrence of pseudohypertrophy and to investigate the contribution of myocardial ischemia on its production during pacing and dobutamine stress echocardiography, we produced a physiologically significant coronary stenosis in 14 open chest dogs. The stenosis in the circumflex artery was measured by quantitative coronary angiography (range: 50% to 89% reduction in luminal diameter), and no resting segmental wall-motion abnormalities were observed by epicardial echocardiography (short-axis, papillary level). In each study, dobutamine (5-40 microg/kg/min) and pacing (up to 260 beats/min) were performed randomly. Positivity of stress echocardiography tests was quantitatively determined by a significant (P < 0.05) reduction or failure to increase in absolute and percent systolic wall thickening in the myocardial area supplied by the stenotic artery as compared to the left anterior descending (LAD) artery-related areas. Diastolic wall thickness and left ventricular diastolic area were compared before and after each stress test in the circumflex and LAD artery-related regions. Pseudohypertrophy was observed in 57% and 86% of dogs for pacing and dobutamine, respectively, in the circumflex region, and in 50% and 64% in the LAD region. Despite its increased incidence in the circumflex region, the augmented diastolic wall thickness did not correlate with coronary stenosis severity or stress test positivity, but correlated inversely with changes in left ventricular diastolic area. In addition, it correlated directly with changes in heart rate only for pacing. In conclusion, pseudohypertrophy was a frequent finding during pacing and dobutamine stress echocardiography tests but was not related to myocardial ischemia in this animal model.
authors.affiliation: Division of Cardiology, University Hospital, Medical School of Ribeirão Preto, Univeristy of São Paulo, 14049-900, Ribeirão Preto, São Paulo, Brazilbr. aschmidt@usp.br
authors.forename: André
authors.initials: A
authors.lastname: Schmidt
authors.forename: Oswaldo
authors.initials: O
authors.lastname: César de Almeida Filho
authors.forename: Elias
authors.initials: E
authors.lastname: Mello Ayres-Neto
authors.forename: João José
authors.initials: JJ
authors.lastname: Carneiro
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Marin-Neto
authors.forename: Benedito Carlos
authors.initials: BC
authors.lastname: Maciel
mesh_terms: D000818:Animals; D023921:Coronary Stenosis / Q000000981:diagnostic imaging; D004195:Disease Models, Animal; D004280:Dobutamine; D004285:Dogs; D025401:Echocardiography, Stress / Q000379:methods*; D005260:Female; D006334:Heart Function Tests; D006439:Hemodynamics / Q000502:physiology; D017379:Hypertrophy, Left Ventricular / Q000150:complications / Q000000981:diagnostic imaging*; D016014:Linear Models; D008297:Male; D017202:Myocardial Ischemia / Q000150:complications / Q000000981:diagnostic imaging*; D011336:Probability; D018570:Risk Assessment; D012680:Sensitivity and Specificity
chemical_list: D004280:Dobutamine