John Alexander MacWilliam (31 July 1857 – 13 January 1937), a physiologist at the University of Aberdeen in the late nineteenth and early twentieth centuries, was a pioneer in the field of cardiac electrophysiology.

[1] He was the first to accurately describe the condition of arrhythmia (irregular heartbeat), and he suggested transthoracic pacing to treat transient asystole (cardiac arrest).

[2] Although his work was recognised within his lifetime, it was not until many decades later that it laid the foundations for developments in the understanding and treatment of life-threatening heart conditions, such as in the artificial cardiac pacemaker.

MacWilliam was appointed Regius Professor of the Institutes of Medicine (later Physiology) at the University of Aberdeen[3] at the age of 29 in 1886, and remained in that post for 41 years until his retirement in 1927.

His parents were William McWilliam (1814 - 1888) and his wife Isabella Cumming (1816 - 1887) who had moved around 1850 from the neighbouring parishes of Inveravon (sometimes spelled Inveraven) and Knockando on Speyside to the farm at Culmill.

He logically extended his experiments on ventricular fibrillation in lower animals to humans, surmising that this arrhythmia was the cause of sudden death.

[12] He also described the basic elements of cardiopulmonary resuscitation - commonly abbreviated as CPR - (ventilation and cardiac compression) in keeping his experimental animals alive.

For example, he described the technique of transthoratic pacing for transient bradycardia (abnormally slow heartbeat), and he proposed stimulating the heart during asystole (cardiac arrest) by causing "artificial excitation" with a series of induction shocks (rather than using constant strong electric currents that could trigger fibrillation).

He listed several potential triggers of ventricular fibrillation in individuals with underlying cardiac disease that could lead to a "hypersensitive state" of the heart.

Although his research work continued throughout his career, his focus moved more towards his teaching role after taking the physiology chair in Aberdeen in 1886.,[4][7] He retired in 1927 at the age of 70.

Amongst his students at Aberdeen were many who went on to outstanding achievements of their own, including John James Rickard Macleod (joint Nobel prize-winner in 1923 for the discovery of insulin).

[9] [2] [4] [8] [9] It would be more than 60 years before MacWilliam's research on arrhythmias and their treatment was translated into clinical approaches that physicians and surgeons could use in patient care.

In 1989, Regis de Silva of Harvard University wrote: "MacWilliam devised methods that laid the foundations for modern cardiac research and that provided the first comprehensive approach to successful cardiac resuscitation" and "MacWilliam’s basic physiologic concepts have survived for a century, greatly influencing more than three generations of research and practice in clinical cardiology".

In his lengthy obituary in the Aberdeen University Review[13] Professor Hugh Maclean states that "He lived thirty years before his time" and "It is now obvious that the value of his contributions can hardly be overestimated".

Edith died in November 1893 at the age of 33, of malaria contracted in the Canary Islands while her husband travelled on to South Africa.

In Aberdeen she involved herself in a variety of social work, including caring for soldiers returning from service during World War I.