Book Review A Practice of Cardiac Pacing By Seymour Furman, David L. Hayes, and David R. Holmes, Jr. 480 pp., illustrated. Mount Kisco, N.Y., Futura, 1986. $59.50. A Guide to Cardiac Pacemakers: Supplement 1986–1987 By Dryden Morse, Robert M. Steiner, and Victor Parsonnet, with four contributors. 207 pp., illustrated. Philadelphia, F.A. Davis, 1986. $50.