In 1971, a scientist called Spickler hypothesised that if one could stick a small device directly into the heart then we could avoid some of the problems. It has taken over 40 years for Spicklers ideas to become reality and this is largely because improvements in technology and integrated circuit boards have meant that you can now confine all the components of a pacemaker into a device of less tan 1 cubic centimetre. In 2014, the first leadless pacemaker was finally produced. There are now 2 such devices - the first is known as a MIcra and the other is called Nanostim.
Both forms of leadless pacemaker are implanted into the heart through veins in the leg. The femoral vein is punctured, a large sheath is inserted and through this a delivery catheter which holds the pacemaker is inserted and pushed all the way to the right heart under X-ray guidance and when it reaches the right spot (usually the septum of the right ventricle), the pacemaker is deployed and left in the heart and the catheter is pulled out. The micra devices has tines which attach onto the wall and therefore the device becomes securely attached to the heart and there is minimal risk of it moving.
So whilst we know that it is possible to implant these, the next question is about safety and efficacy. In 2015, the safety experience from the implantation of over 700 micra devices was published and it was noted that a successful implantation was achieved in more than 99% of patients and at 6 months, the rate of complications was 4% compared to 7.4% with traditional pacemakers. Whilst many of the complications were not dangerous, there was a 1.6% risk of cardiac perforation. This was obviously concerning and have been studied further and a later study of 1345 patients suggested that the rrisk of cardiac perforation was actually much lower at 0.37%. An important thing to note was the device infection risk was very very low with the leadless systems.
