Rapid Resolution of Hyperkinesis After Exercise: Methods
Exercise-induced wall motion abnormalities, visualized by two-dimensional echocardiography, suggest the presence of coronary artery disease with a sensitivity of 70 to 94 percent, and a specificity of 67 to 92 percent. Hyperkinetic wall motion, on the other hand, is predictive of an excellent prognosis. The normal, hyperkinetic response to exercise is transient; and there are few data on the time course of resolution. The duration of normal, hyperkinetic wall motion is important to recognize because of the implications regarding prognosis. Our purpose, therefore, was to measure regional wall thickening in normal subjects before and serially after exercise, and to determine the duration of exercise-induced hyperkinesis.
Eight normal male subjects (age, 29 ±4 years; range, 25 to 33 years) were studied. All subjects gave informed consent. The institutional committee on human research approved the study protocol. All had a normal history, physical examination, and 12-lead electrocardiogram. In addition, they were screened to assure adequate acoustic windows prior to exercise and echocardiographic imaging. The chest wall was marked with a marker in order to approximate imaging of similar acoustic windows at baseline and after exercise.
Exercise Echocardiography Protocol Two-dimensional echocardiographic images were obtained with an echocardiographic machine (Hewlett-Packard Sonos 1000), using 2.5- or 3.5-MHz transducers. Parasternal long-axis and short-axis, as well as apical four- and two-chamber views, were obtained prior to exercise. Subjects were exercised on a treadmill according to the maximal Bruce protocol to at least 85 percent of their predicted maxima] heart rate for age and to completion of stage 5 of the protocol. Electrocardiograms were recorded during each of the five stages of exercise, then at immediate recovery, and at 1, 3, and 5 min postexercise.
Immediately after completion of exercise, the subjects were placed in a left lateral decubitus position. Within 2 min of exercise, the echocardiographic examination was repeated. Acoustic windows for parasternal views were chosen to obtain similar views as baseline. At 2 to 4 and 5 to 7 min after exercise, additional imaging was performed. At each of the echocardiographic examinations, gain settings were optimized to identify endocardial borders without “blooming” of the surfaces.