The pacemaker is one of the most important inventions in medical science. In an era where many individuals battle heart-related illnesses such as heart block, the pacemaker has become a lifesaving device that restores the rhythm of the human heart.
John Alexander Hopps, OC (May 21, 1919 – November 24, 1998), was a pioneering Canadian medical researcher whose work was central to the creation of the cardiac pacemaker.
In 1965, Dr. Hopps established the Canadian Medical and Biological Engineering Society and served as its first president. He later became president (1971) and then secretary general (1976–1985) of the International Federation for Medical and Biological Engineering. From 1985 to 1988, he served as secretary general of the International Union for Physical and Engineering Sciences in Medicine.
Hopps spent most of his career working with the Medical Engineering Group at the National Research Council of Canada, which he joined in 1941 after graduating from the University of Manitoba.¹
In the 1940s, Hopps was studying radiofrequency heating to pasteurize beer in Ottawa. When he was reassigned to the Banting Institute in 1949, he considered it an interruption—but this move led to a major medical breakthrough.
At the Institute, cardiac surgeon Dr. Wilfred Bigelow and research fellow Dr. John Callaghan used hypothermia to slow the heart during surgery. Overcooling often stopped the heart because it could no longer depolarize.
Hopps observed that electrical impulses could restart contractions, and repeated impulses could maintain them—a process now known as pacing.
Returning to the National Research Council in 1950, Hopps built the first pacemaker prototype.
The device was:
the size of a small table radio (about 30 cm)
powered by household current
built using vacuum tubes
He also developed transvenous catheter electrodes inserted through the external jugular vein—a design that remains the foundation of modern pacing leads.
Hopps’ research paved the way for the world’s first implantable pacemaker.
When transistor technology replaced vacuum tubes, devices became small enough for implantation.
Engineer Rune Elmqvist designed the first implantable pacemaker using two transistors in a modified shoe-polish tin. On October 8, 1958, surgeon Åke Senning implanted it in Arne Larsson, a 43-year-old patient experiencing repeated Stokes–Adams attacks.
Larsson’s first two pacemakers failed within hours to days, but later devices kept him alive for decades. He underwent 26 device replacements and died in 2001 from unrelated causes.²
Single-Chamber Pacemaker: Stimulates either the right atrium or right ventricle.
Dual-Chamber Pacemaker: Coordinates timing between atrium and ventricle.
Biventricular Pacemaker (CRT): Stimulates both ventricles; used in heart failure.
Leadless Pacemaker: Miniature device implanted directly in the heart.
Temporary Pacemaker: External device used short-term.
Implantable Cardioverter-Defibrillator (ICD) with Pacing: Provides pacing plus life-saving shocks.³
Although generally safe, pacemaker implantation is still a surgical procedure.
Potential risks include:
lead malfunction
pneumothorax
infection
bleeding
Large clinical studies estimate major acute complications occur in 3–6% of cases, depending on patient factors and hospital experience.¹
John Hopps’ work revolutionized cardiac care and paved the way for devices that save millions of lives today. From the first external machine to the modern leadless pacemaker, the evolution of this technology continues to transform cardiology.
1. Bains, Perminder, Safia Chatur, Maya Ignaszewski, Simroop Ladhar, and Matthew T. Bennett. "John Hopps and the Pacemaker: A History and Detailed Overview of Devices, Indications, and Complications." British Columbia Medical Journal 59, no. 1 (January/February 2017): 22–28. https://bcmj.org/articles/john-hopps-and-pacemaker-history-and-detailed-overview-devices-indications-and.
2. IEEE History Center. "Milestones: First External Cardiac Pacemaker, 1950." Engineering and Technology History Wiki. Last modified June 14, 2022. https://ethw.org/Milestones:First_External_Cardiac_Pacemaker,_1950.
3. StatPearls. “Pacemaker Types and Selection.” StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024. https://www.ncbi.nlm.nih.gov/books/NBK556011/.
Edited by M Subha Maheswari