Next-generation pacemakers: from electrical devices to biological pacemakers

The invention of an electric pacemaker in the middle of the 20th century led to a revolution in the treatment of cardiac conduction system diseases. The improvement of pacemakers continued. In 1962, the first small series of external pacemakers for percutaneous and direct stimulation was produced in Kaunas. After a while, electric pacemakers became more reliable, smaller and lighter in weight, but the problem of foreign body associated infection and limited service life remained unresolved. Modern high-tech medicine strives to create less invasive electric pacemakers, but nevertheless, biological pacemakers can expand the therapeutic arsenal for the treatment of cardiac patients, being the most physiological for humans. The concept of an artificial biological pacemaker consists of the creation of an organic structure that generates a spontaneous rhythm from the implantation site in the myocardium. Various gene and cellular approaches were used to create biological pacemakers: a functional reorganization approach (use of adenovirus vectors for hyperexpression of genes encoding ion channels in cardiomyocytes); hybrid approach (use of fibroblasts to deliver genes of ion channels that provide heart automation); somatic reprogramming approach (overexpression of the transcription factor TBX18 using adenoviral vectors, which reprograms cardiomyocytes into induced sinoatrial node cells, creating cardiac stimulatory activity); cellular approach (transplantation of stem cells to a specific place in the heart, thereby creating biological stimulation). Modern methods of electrical cardiac stimulation and the developed concepts of the biological pacemaker clearly show the possibility of eliminating current problems associated with the use of an artificial pacemaker by replacing it with a biological one. Each of the approaches (gene, cellular, hybrid-cellular, somatic reprogramming) has its own advantages and disadvantages, which predisposes to further study and improvement in order to introduce a biological pacemaker into clinical practice.