DIAGNOSTIC METHODS PERIOPERATIVE MYOCARDIAL INFARCTION Quantative two-dimensional echocardiographic analysis of regional wall motion in patients with perioperative myocardial infarction

Regional left ventricular wall motion was evaluated by two-dimensional echocardiographic techniques with fixedand floating-axis analytical algorithms in three groups of subjects: normal subjects (n = 15), patients undergoing uncomplicated coronary artery bypass graft surgery (CABG) (n = 10), and patients suffering perioperative myocardial infarction (n 27). In patients undergoing uncomplicated CABG, fixed-axis analysis in the apical four-chamber view produced septal hypokinesis indistinguishable from the septal hypokinesis seen in patients with anterior myocardial infarction. In addition, fixed-axis analysis enhanced lateral wall motion so that patients with lateral myocardial infarction were classified as normal. Floating-axis analysis corrected these limitations by (1) producing regional left ventricular wall motion in the patients undergoing uncomplicated CABG, which was identical to that in normal subjects, and (2) producing regional left ventricular wall motion in patients with myocardial infarction that was hypokinetic in segments corresponding to the electrocardiographic area of involvement. In patients with new Q waves, fixed-axis analysis detected abnormalities of regional left ventricular wall motion in 24 of 34 (71 %) electrocardiographically involved regions but also classified 44 of 100 segments in uncomplicated patients as abnormal. Floating-axis analysis detected regional left ventricular wall motion abnormalities in 30 of 34 patients (88%; p < .05 vs fixedaxis analysis) and only 15 of 100 segments in patients undergoing uncomplicated CABG were classified as abnormal (p < .001 vs fixed'-axis analysis). We conclude that floating-axis analysis is a more accurate and clinically relevant method of evaluating regional left ventricular wall motion in patients undergoing CABG who suffer myocardial infarction as a perioperative complication. Circulation 70, No. 2, 233-241, 1984. SEVERAL studies have used noninvasive techniques to evaluate regional left ventricular function after acute myocardial infarction and have demonstrated that these analyses can provide valuable diagnostic and prognostic information.`' Similar studies have not been performed in patients undergoing coronary artery bypass graft surgery (CABG). This may be due in part to the difficulty in assessing postoperative regional function, particularly that of the interventricular septum, which has been found to be abnormal even when there is no other evidence of myocardial infarction.5-5 Recent work from this institution'6 and others'l7 1 has suggested that such abnormal motion of the intervenFrom the Departments of Medicine (Cardiology) and Surgery, Brockton and West Roxbury Veterans Administration Medical Centers; Brigham and Women's Hospital; and Harvard Medical School, Boston. Supported by the Medical Research Service of the Veterans Administration. Address for correspondence: Thomas Force, M.D., Veterans Administration Medical Center, 1400 V.F.W. Parkway, West Roxbury, MA 02132. Received Feb. 10, 1984; revision accepted April 26, 1984. tricular septum appears to be caused by exaggerated systolic anteromedial translation of the entire heart within the chest, as viewed from a fixed external frame of reference. We have demonstrated in patients with uncomplicated perioperative courses and normal septal function (as shown by preservation of systolic thickening of the interventricular septum) that the apparent deterioration in septal motion can be corrected by analyzing regional wall motion with an internal frame of reference or floating-axis analysis system.'6 Floatingaxis analysis not only corrects the abnormal motion of the septum but also normalizes the apparently enhanced motion of the lateral wall of the left ventricle concomitantly produced when a fixed external frame of reference is used. These data, obtained from a homogeneous patient population with no evidence of perioperative myocardial dysfunction, implied that two-dimensional echocardiographic examination with a floating-axis system of analysis may represent a noninvasive method of Vol. 70, No. 2, August 1984 233 by gest on M ay 8, 2017 http://ciajournals.org/ D ow nladed from