You will be given a definition of a task first, then some input of the task.
In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.

Context: There are several studies on myocardial tissue Doppler velocities during dobutamine stress, but few studies on the same parameters during bicycle exercise. We wanted to examine how sample sites affected velocities, beat-to-beat variability and segments eligible for analysis.', 'Twenty patients with normal coronary arteries were included in the study. Echocardiograms were obtained at rest and at peak exercise on the exercise bike and were analyzed off line by two independent raters.\Question: Do feasibility of using tissue Doppler velocities in stress echo during upright bicycle exercise?
Output:
Tissue velocities decreased from base to apex. Mean difference between the raters was-0.02 cm/sec at rest and 0.45 cm/sec during exercise. Peak-to-peak variability was lowest in the mitral ring during rest (10-14%) and increased at peak exercise (15-21%). The proportion of segments eligible for analysis was 84% in the septum and 67% in the anterior wall during exercise. Thus, in patients with normal coronary arteries, tissue Doppler velocities decrease from base toward the apex during bicycle exercise. Interrater agreement is reduced during exercise and beat-to-beat variability is lowest in the mitral ring.