In arecent plenary address to the American College of Cardiology, Dr. Leroy Hood stated that he expected the application of the techniques of recombinant DNA and molecular biology to medicine would advance the field more in the next twenty years than all of the progress that has been made in the past 2,000 years. Cardiology, as a discipline, has been one of the last to embrace the techniques of molecular biology, yet the advances made in the past five years have indeed been dramatic. Throm- bolytic therapy, introduced with a bang through the use of recombinant tissue plasminogen activator...