Dr. Waldo’s career in academic medicine began in 1966 at the College of Physicians and Surgeons of Columbia University, where he was a postdoctoral fellow (2 years in the laboratory of Dr. Brian F. Hoffman in the Department of Pharmacology and one year in the Cardiovascular Laboratory of the Department of Medicine). He became a member of the faculty in the Department of Pharmacology. In 1972, he moved to the University of Alabama at Birmingham in the Department of Medicine, where he stayed for 14 years. Today he is at Case Western Reserve University in the Department of Medicine, where he has been since 1986 as The Walter H. Pritchard Professor of Cardiology, Professor of Medicine and Professor of Biomedical Engineering.

By measure of both Dr. Waldo’s research and clinical interests, he is one of the major leaders in our field currently and has been for a long time. More importantly he helped to develop the field of clinical cardiac electrophysiology.

Dr. Waldo’s distinguished research career has spanned more than 3 decades. In 1966, he was the first to use the human open heart operating room systematically as a cardiac electrophysiology laboratory both to map the electrical activation of the human heart directly and to study its electrophysiological properties. 17 of his first 39 papers dealt with normal and abnormal cardiac electro­physiology studied in patients during open heart surgery. The studies included mapping the course and extent of the specialized AV conduction system, including in patients with complex congenital heart disease (this work importantly lead to an improvement in surgical technique to minimize the previously very high incidence of complete heart block due to trauma at the time of surgical repair); studies on the nature of atrial activation during ectopic excitation of the atria and its relationship to P wave polarity and morphology in the ECG and to the P-R interval (which led to new understanding of retrograde atrial activation and AV conduction); mapping studies of ventricular arrhythmias, including for the surgical treatment of ventricular tachycardia; the direct study of the specialized AV conduction system to establish norms for conduction intervals and conduction velocity (this established norms for important parameters such as the H-V interval); and the study of atrial excitability and conduction during rapid atrial pacing.

Dr. Waldo also developed the use of temporary epicardial wire electrodes for the diagnosis and treatment of cardiac arrhythmias following open heart surgery. Using these techniques, he not only advanced but continued to develop the use of recording and antitachycardia pacing techniques in general (in fact, they became a standard part of antitachycardia pacing algorithms now in routine use in antitachycardia pacemakers and implantable cardioverter-defibrillators), but also, importantly, he utilized these techniques to learn more about the nature of various cardiac arrhythmias. Thus, his postoperative studies led to the recognition and characterization of a very rapid form of atrial flutter; the further characterization of classical atrial flutter; and a new characterization of atrial fibrillation.

Most noteworthy of all of his many contributions is his recognition, education and explanation of the important phenomenon of entrainment of arrhythmias with cardiac pacing. The concept of transient entrainment is currently a central part of clinical cardiac electrophysiological characterization and treatment of arrhythmias. Entrainment permits the clinician to distinguish reentrant rhythms from automatic and triggered rhythms. In fact, it is the only way clinically to identify the presence of a reentrant cardiac arrhythmia. Moreover, using the techniques of entrainment during electrophysiologic study permits the clinical cardiac electrophysiologist to define the reentrant circuit carefully, and helps localize the critical sites in the reentrant circuit as targets for radiofrequency ablation. It is particularly important for the radiofrequency ablation of atrial flutter and ventricular tachycardia. Moreover, the principles of entrainment have been incorporated into antitachycardia pacing algorithms in pacemakers and implantable cardioverter defibrillators, thereby permitting effective interruption of reentrant tachycardias.

With respect to today’s lecture, Dr. Waldo has been a pioneer in the field of atrial tachyarrhythmias. He is especially well known for his studies of the nature and mechanism of atrial flutter and atrial fibrillation commencing with his seminal work that identified and characterizate of the course and extent of the atrial flutter reentrant circuit in patients. Furthermore, he developed the canine sterile pericarditis model of atrial flutter and atrial fibrillation, which, to this day, continues to be used widely to understand the mechanisms of these arrhythmias and their treatment by various clinical interventions, including antiarrhythmic drugs, cardiac pacing, cardioversion, and ablation techniques. His studies of atrial fibrillation and atrial flutter in this canine model have contributed significantly to our understanding of the nature and mechanism of these arrhythmias, most recently including figure-of-eight reentry atrial flutter; and two mechanisms of atrial fibrillation, both due to a “driver” which produces fibrillatory conduction, one driver being unstable reentrant circuits of very short cycle length, and another being a single, stable reentrant circuit of short cycle length. These concepts are important parts of every day clinical and research studies, and include the understanding and interpreting of double potential electrograms, now understood on the basis of his work to be a marker of conduction block; and fractionated electrograms, now recognized to be a manifestation of slow conduction.

It is an honor to have him as the 13th GMK lecturer.