in addition to negative chronotropic action ( leftward shift along the dt-hr curve ) , prevention of disproportionate dt shortening at peak exercise ( upward shift of the dt-hr curve ) with propranolol through its beneficial action on myocardial ischemia tends to increase myocardial perfusion in patients who , when off propranolol , had ischemic response to exercise .
C1372752
negative chronotropic
C0033497
propranolol