Dobutamine Dual Isotope Stress Test For patients who are unable to exercise adequately on the treadmill and can’t take adenosine, the drug dobutamine may be given to produce an effect on the heart similar to exercise. During the test, you will be lying on the stretcher and the drug dobutamine will be infused slowly through your IV. The dobutamine dosage you will be given is based on your body weight, and the dose is increased every three minutes to a maximum dose or until you reach the target heart rate. If your heart rate has not reached the predicted "target" heart rate, the cardiologist will have the nurse give you a drug called atropine through your IV. Once your heart rate is at or has exceeded your "target" heart rate, you will receive the second radioactive isotope, Cardiolite through your IV. The dobutamine will then be shut off and the test terminated. Sometimes the cardiologist will have the nurse give you a drug called Brevibloc (or esmolol) through your IV if your heart rate is taking a long time to decrease. You will be given some time to rest before having your second scan under the nuclear camera. Please do not leave the area until you have been instructed that your test has been completed.