The new era of miniaturization started with leadless devices and currently there are companie which are into leadless pacing devices. The first is the device called Micra Transcatheter Pacing System (TPS), made by Medtronic Inc. which is the ‘world’s smallest pacemaker’ (93% smaller than a conventional pacemaker) with dimensions of just 7 mm in width, 26 mm long and 2 g in weight. The estimated battery life was around 10 – 12 years. The TPS uses self-expanding Nitinol tines to fixate in the trabeculae.

Nanostim device is manufactured by Abbott Inc. The device is smaller than a AAA battery and can be directly placed inside the heart through the femoral route approach. Implantation Technique: Nanostim LPS has a screw-in helix. This 4-cm long, 6-mm wide,and just 2 g in weight LCP It has a long battery life of 9 -10 years.

A Wireless Cardiac Stimulation system (WiCS-LV) is also being developed by EBR Systems (Sunnyvale, CA, USA). The system utilizes ultrasound emitted from a transmitter implanted subcutaneously in the left chest and a receiver implanted in the ventricle which converts ultrasound energy to electrical energy that can be used to pace the heart.

In contrast to the aforementioned devices, the WiCS-LV system has been used in cardiac resynchronization therapy (CRT) when used with conventional right ventricular pacers. Hence both ventricles will contract almost simultaneously which allows resynchronization. It should be noted that Nanostim from St Jude Medical (now Abbott) is not available commercially while WiCS – LV is not commercially launched in many countries worldwide.