The early history of cardiac pacing

Abstract

John McWilliam was appointed Regius Professor of the Institutes of Medicine (later Physiology) at the University of Aberdeen in 1886, at the age of only 29. The following year he established that electric shocks induced ventricular fibrillation (VF) and, having witnessed this phenomenon in many animals, including mammals, concluded it must also be a cause of sudden death in humans. His research then focused on ways of restarting the heart after cardiac arrest. While he recognised that most cardiac arrests were hopeless, he considered there were probably some situations, such as excessive vagal stimulation, which could be reversible. Believing that one single dramatic shock would induce VF and knowing that a small shock would only lead to a single cardiac contraction, he proposed ‘We want a much more effective and speedy mode of exciting rhythmic contraction . . . a periodic series of single induction shocks sent through the heart at approximately the normal rate of cardiac action’. McWilliam used a single electrode inserted into the apex of the ventricle of experimental animals, firing at a regular rate determined by a metronome. He quickly realised that this stimulated effective ventricular contractions but the effect was diminished by the lack of atrial contraction. He also noted the paced contractions eventually led to more spontaneous contractions and improved coronary blood flow. For this to be an effective external technique in man, McWilliam postulated the electrical stimulus would have to be applied across the heart to allow atrial and ventricular contraction, proposing two large sponge electrodes soaked in strong salt solution be applied ‘[one] in front over the area of cardiac impulse, and the other over the region of the fourth dorsal vertebra’. This arrangement seemed to him ‘the only rational and effective one for stimulating by direct means the action of the heart which has been suddenly enfeebled’. Following the development of the electrocardiograph, his theories on VF in humans were eventually accepted, but there were no clinical developments related to his pioneering resuscitation work over the following decades. Towards the end of McWilliams’ life, there were some who attempted to translate his research into clinical practice. Mark Lidwill, an Australian physician and anaesthetist, presented a pacing device at a meeting of the Australasian Medical Congress in 1929. Unfortunately there are no known drawings or photographs of this machine, designed with the help of Edgar Booth in the physics department at the University of Sydney. It was intended for resuscitation, not for long-term pacing, but was almost certainly the first pacemaker used successfully on a human. Lidwill’s colleague, Dr Briggs, used the original device on several occasions on stillborn babies, one of which was successfully resuscitated. It is unclear whether Lidwill was present on those occasions or ever personally used the device on a patient. He acknowledged the original device used by Briggs was too complicated and presented a simplified, portable version of the machine at the 1929 meeting. It delivered a variable rate from 80–120 impulses/minute at around 16 volts. Lidwill felt Cover photo. Electrodyne pacemaker and defibrillator developed by Paul Zoll. Source: Image courtesy of the Wood LibraryMuseum of Anesthesiology, Schaumburg, Illinois, USA.