A method of performing a medical procedure, such as surgery, is provided. A nerve is stimulated in order to adjust the beating of the heart to a first condition, such as a stopped or slowed condition. The medical procedure is performed on the heart or another organ. The stimulation of the nerve is stopped in order to adjust the beating of the heart to a second condition, such as a beating condition. The heart itself may also be stimulated to a beating condition, such as by pacing. The stimulation of the nerve may be continued in order to allow the medical procedure to be continued. A sensor to sense a characteristic of a fluid or tissue, such as an impending contraction, may be also used during the medical procedure. Systems and devices for performing the medical procedure are also provided.