Friday, January 10, 2014

Happy Birthday, Earl Bakken!

Today, Earl Bakken turns 90 years old. Bakken is the founder of the medical device company Medtronic, and he played a key role in the development of the artificial pacemaker. I had the good fortune to meet Bakken in 2009 at a reception in the Bakken Museum as part of the 31st Annual International Conference of the IEEE Engineering in Medicine and Biology Society held in Minneapolis.

Kirk Jeffrey’s book Machines in our Hearts tells the story of how Bakken, at the request of the renowned heart surgeon C. Walton Lillehei, developed the first battery powered pacemaker.
“Bakken first thought of an ‘automobile battery with an inverter to convert the six volts to 115 volts to run the AC pacemaker on its wheeled stand. That, however, seemed like an awfully inefficient say to do the job, since we needed only a 10-volt direct-current pulse to stimulate the heart.’ Powering the stimulator from a car battery would have eliminated the need for electrical cords and plugs, but would not have done away with the wheeled cart. Bakken then realized that he could simply build a stimulator that used transistors and small batteries. ‘It was kind of an interesting point in history,’ he recalled—‘a joining of several technologies.’ In constructing the external pulse generator, Bakken borrowed a circuit design for a metronome that he had noticed a few months earlier in an electronics magazine for hobbyists. It included two transistors. Invented a decade earlier, the transistor was just beginning to spread into general use in the mid-1950s. Hardly anyone had explored its applications in medical devices. Bakken used a nine-volt battery, housed the assemblage in an aluminum circuit box, and provided an on-off switch and control knobs for stimulus rate and amplitude.

At the electronics repair shop that he had founded with his brother-in-law in 1949, Bakken had customized many instruments for researchers at the University of Minnesota Medical School and the nearby campus of the College of Agriculture. Investigators often ‘wanted special attachments or special amplifiers’ added to some of the standard recording and measuring equipment. ‘So we began to manufacture special components to go with the recording equipment. And that led us into just doing specials of many kinds…We developed….animal respirators, semen impedance meters for the farm campus, just a whole spectrum of devices.’ Usually the business would sell a few of these items. When Bakken delivered the battery-powered external pulse generator to Walt Lillehei in January 1958, it seemed to the inventor another special order, nothing more. The pulse generator was hardly an aesthetic triumph, but it was small enough to hold in the hand and severed all connection between the patient’s heart and the hospital power system. Bakken’s business had no animal-testing facility, so he assumed that the surgeons would test the device by pacing laboratory dogs. They did ‘a few dogs,’ then Lillehei put the pacemaker into clinical use. When Bakken next visited the university, he was surprised to find that his crude prototype was managing the heartbeat of a child recovering from open-heart surgery.”
Russ Hobbie and I discuss the artificial pacemaker in Chapter 7 of the 4th edition of Intermediate Physics for Medicine and Biology
“Cardiac pacemakers are a useful treatment for certain heart diseases [Jeffrey (2001), Moses et al. (2000); Barold (1985)]. The most frequent are an abnormally slow pulse rate (bradycardia) associated with symptoms such as dizziness, fainting (syncope), or heart failure. These may arise from a problem with the SA node (sick sinus syndrome) or with the conduction system (heart block). One of the first uses of pacemakers was to treat complete or “third degree” heart block. The SA node and the atria fire at a normal rate but the wave front cannot pass into the conduction system. The AV node or some other part of the conduction system then begins firing and driving the ventricles at its own, pathologically slower rate. Such behavior is evident in the ECG in Fig. 7.30, in which the timing of the QRS complex from the ventricles is unrelated to the P wave from the atria. A pacemaker stimulating the ventricles can be used to restore a normal ventricular rate.”
You can learn more about Bakken’s contributions to the development of the pacemaker here or on video here. Visit his website here or read his autobiography. He now lives in Hawaii, where local magazines have reported about him here and here. Those wanting to join the celebration can attend Earl Bakken’s birthday bash at the Bakken Museum, or celebrate at the North Hawaii Community Hospital.

Happy birthday, Earl Bakken!

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