Health Sciences · Temerty Faculty of Medicine
A flat, metal encased, implantable, medical device with a rounded profile. One side of the metal case is labelled with information from the manufacturer.
At the top of the artifact there is a clear plastic socket with a pacing lead attached. The area beneath the attachment point is marked with a negative and a positive sign.
Accession Number: 2020.med.36
Alternative Name:
Primary Materials: Metal, Plastic
Printed on one face of the pacemaker: “MINIX TM ST 8330” , “VVI” , “MULTI-PROGRAMMABLE” , “SN UN4101807M” , “MEDTRONIC” , “CANADA”
Printed on the pacing lead: “IS-1 BI VEN”, “AJ084194V”.
Dimensions (cm): Hight = 5, Width = 0.5, Length = 23.5.
A pacemaker is an implantable prosthetic device that is used to regulate the natural electrical signal that governs the contractions of the heart. Pacemakers are used in cases when the natural signal is weak, irregular, or impeded. The pacemaker is typically implanted below the collarbone under the skin of the chest with one or more pacing leads entering the heart through a vein.
This is a sophisticated multiprogrammable pacemaker that was in use in the mid-1990s. Multiprogrammability refers to the capacity to change multiple parameters of an implanted pacemaker using radiofrequency communication. In this way, an implanted device can be adjusted as a patient’s condition progresses.
The artifact is in good cosmetic condition. The tubing may have some slight discoloration and the round flat metal casing has some slight scratching.
Associated Instruments:
Manufacturer: Medtronic plc. Minneapolis, MN, USA.
Date of Manufacture: Circa mid 1990s.
This artifact belongs to a small collection of items related to cardiac surgery that was collected by Dr. Wilfred Gordon “Bill” Bigelow (1913 – 2005). After his death, the collection was donated to the Cardiovascular Sciences Collaborative Program of the University of Toronto, where it is currently on display.
Edward Shorter, Hugh E Scully, and Bernard S Goldman (2022). The Heartbeat of Innovation : A History of Cardiac Surgery at the Toronto General Hospital. University of Toronto Press.
This pacemaker is one of three belonging to a small collection gathered by the heart surgeon Dr. Wilfred Gordon “Bill” Bigelow (1913 – 2005). It has a special significance due to Dr. Bigelow’s contribution to the technology’s establishment. This history is recounted in “The Pacemaker Story: A Cold Heart Spinoff”, published by Bigelow in 1987, as well as in the 2022 history of cardiac surgery at Toronto General Hospital by Shorter, Scully, and Goldman.
The earliest developments date to 1949 and involve research by Bigelow and his team into microcirculation and hypothermia in anesthetized dogs. During one experiment, in which he found himself unable to resuscitate a dog in cardiac arrest, Bigelow poked the left ventricle with forceps and found that this made the heart contract. Repeating the gesture produced an effect resembling a heartbeat. The dog was resuscitated and recovered.
This experience inspired Bigelow and his colleague Dr. John Callaghan to experiment with electrical stimulation of the heart. Working first with a commercial Grass signal generator, then with an apparatus built by engineer Jack Hopps of the National Research Council in Ottawa, the group created an external pacemaker that could regulate the heart rate of a dog. The mature design was housed in a table-top electronics console to which was attached a single “bipolar” electrode that was passed through an incision in the neck and through the jugular vein until it reached the sinoatrial node of the heart.
The group presented their work on October 23, 1950 at the meeting of the American College of Surgeons in Boston, Massachusetts. This garnered media coverage, notably a piece in the New York Times. They subsequently provided the circuit diagram to American surgeon Paul Zoll, who used it in the first successful treatment of heart block in humans.
The technology then entered a phase of development with various investigators working towards creating a useful implantable technology. The key development was the availability of early transistors that permitted the creation of a miniaturized, battery powered device. A breakthrough came with the work of Åke Senning of Stockholm who implanted the first practical device in 1958.
Medtronic was one of the early incumbent pacemaker manufacturers as the field emerged over the 1950s and 1960s. This pacemaker from the 1990s is an example of the technology at maturity. Its lithium-ion battery is reliable and long lasting. The metal casing provides a hermetic seal. Multiprogrammability provides adjustable operational parameters.