Editing Pacemaker (section)

=== Transcutaneous ===
In 1950, Canadian electrical engineer [[John Alexander Hopps|John Hopps]] designed and built the first external pacemaker based upon observations by cardio-thoracic surgeons [[Wilfred Gordon Bigelow]] and [[John Callaghan (physician)|John Callaghan]] at [[Toronto General Hospital]].<ref>{{Cite web|url=http://collectionscanada.gc.ca/pam_archives/index.php?fuseaction=genitem.displayItem&lang=eng&rec_nbr=104318&rec_nbr_list=104318,3588818,815761,4385271,4385234,4385226,4385302,4385311,4385420,4385246|archive-url=https://web.archive.org/web/20200728125042/https://collectionscanada.gc.ca/pam_archives/index.php?fuseaction=genitem.displayItem&lang=eng&rec_nbr=104318&rec_nbr_list=104318,3588818,815761,4385271,4385234,4385226,4385302,4385311,4385420,4385246|url-status=dead|archive-date=2020-07-28|title=John Alexander Hopps fonds|date=2008-03-19|website=Archival description|publisher=[[Library and Archives Canada]]|access-date=16 Sep 2016}}</ref> The device was first tested on a dog at the [[University of Toronto]]'s Banting Institute.<ref>{{cite web|url=http://www.ieee.ca/history/milestones/pacemaker.html|title=IEEE Milestone in Electrical Engineering and Computing|access-date=September 5, 2009|archive-date=February 25, 2021|archive-url=https://web.archive.org/web/20210225103835/http://www.ieee.ca/history/milestones/pacemaker.html|url-status=dead}}</ref> A substantial external device using [[vacuum tube]] technology to provide [[transcutaneous pacing]], it was somewhat crude and painful to the patient in use and, being powered from an AC wall socket, carried a potential hazard of [[electric shock|electrocution]] of the patient and inducing [[ventricular fibrillation]].<ref>{{Cite book |last=Silva |first=Regis A. de |url=https://books.google.com/books?id=NI0LtnwdBg0C&dq=John+Hopps+external+pacemaker+vacuum+tube&pg=PA14 |title=Heart Disease |year=2013 |publisher=ABC-CLIO |isbn=978-0-313-37607-8 |language=en}}</ref>

A number of innovators, including [[Paul Zoll]], made smaller but still bulky transcutaneous pacing devices from 1952 using a large rechargeable battery as the power supply.<ref>{{cite web |title=Paul Maurice Zoll |url=https://news.harvard.edu/gazette/story/2001/04/harvard-gazette-paul-maurice-zoll/ |website=Harvard Gazette |date=19 April 2001 }}</ref>

In 1957, William L. Weirich published the results of research performed at the [[University of Minnesota]]. These studies demonstrated the restoration of heart rate, cardiac output and mean aortic pressures in animal subjects with complete [[heart block]] through the use of a [[myocardial]] electrode.<ref>{{cite journal |vauthors=Weirich WL, Gott VL, Lillehei CW | title = The treatment of complete heart block by the combined use of a myocardial electrode and an artificial pacemaker | journal = Surg Forum | volume = 8 | pages = 360–63 | year = 1957 | pmid = 13529629 }}</ref>

In 1958 Colombian doctor Alberto Vejarano Laverde and Colombian electrical engineer [[Jorge Reynolds Pombo]] constructed an external pacemaker, similar to those of Hopps and Zoll, weighing 45&nbsp;kg and powered by a 12 volt car [[lead–acid battery]], but connected to electrodes attached to the heart. This apparatus was successfully used to sustain a 70-year-old priest, Gerardo Florez.<ref>{{cite journal |last1=Reynolds |first1=Jorge |title=The Early History of Cardiac Pacing in Colombia |journal=Pacing and Clinical Electrophysiology |date=March 1988 |volume=11 |issue=3 |pages=355–61 |doi=10.1111/j.1540-8159.1988.tb05018.x |pmid=2452427 |s2cid=20374411 }}</ref>

The development of the [[silicon]] [[transistor]] and its first commercial availability in 1956 was the pivotal event that led to the rapid development of practical cardiac pacemaking.<ref>{{Cite journal |first2=Victor |last2=Parsonnet |first1=Kirk |last1=Jeffrey |date=19 May 1998 |title=Cardiac Pacing, 1960–1985 |journal=Circulation |volume=97 |issue=19|pages=1978–91 |doi=10.1161/01.CIR.97.19.1978 |pmid=9609092 |doi-access=free }}</ref>