Madsen Pirie

A remarkable example of miniaturization is reported in MIT Technology Review by Susan Young.  It’s the world’s smallest pacemaker (as yet) and can be inserted into the heart after being steered through a large vein accessed from the patient’s thigh.  Last week the device produced by Medtronic was given to a patient in Linz, Austria in the first live trial.  It’s the Micra Transcatheter Pacing System (Micra TPS), and measures only 24mm long, and is 75cc in volume, small enough to be carried along by a catheter.

This kind of ‘keyhole’ surgery has long been in use to unclog arteries using balloons delivered through blood vessels.  Then it was used to insert stents to keep weak or narrow arteries open by holding the walls apart.  Next came heart valves small enough to be delivered into position by similar methods, and now there’s a pacemaker small enough to be delivered in the same way.  The new devices don’t use electrical wires to deliver pulses to the heart, but sit inside it and use small prongs that touch the heart to send the pulse.  Their batteries are claimed to last 8-10 years on full stimulation, after which the device presumably has to be replaced or recharged.  It’s a very positive development for elderly or frail patients for whom major heart surgery would be more risky.  Typically the new procedure would involve local anaesthetic and sedation rather than total anaesthesia.  The new device is a tenth of the size of a conventional pacemaker and reduces the amount of power required.  It sure beats the trauma involved in full surgery, and its procedure is quicker and lest costly.  Good news all round.

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