Multi-nodal nano-actuator pacemaker for energy-efficient stimulation of cardiomyocytes

There is continuous interest in maximizing the longevity of implantable pacemakers, which are effective in remedying and managing patients with arrhythmic heart disease. This paper accordingly first proposes miniature actuating nanomachines that inter-connect with individual cardiomyocytes and then deeply explores their energy expenditure when performing basic cardiomyocyte stimulation tasks. Since evoked electrical impulses from a number of actuated cardiomyocytes could coordinate contraction throughout the remaining heart muscle and lead to a heart beat, the miniature actuating nanomachines acting synchronously form a conceptual multi-nodal nano-actuator pacemaker network. Rectangular-, sine-, half-sine-, and sawtooth stimulation pulses with varying configurations are considered for actuation of a single isolated in-silico cardiomyocyte by each of the nanomachines. Computer optimization methods with energy consumption as a cost function are utilized to configure preferable stimulation signals in terms of numbers of stimulation sessions/pulses, pulse amplitudes, and duration. In addition, the simulation data are compared with experimental data obtained using in-vitro mouse cardiomyocytes. Among the considered waveforms, half-sine pulses that lead to actuation of a single cardiomyocyte consume minimum energy. None of the used sequences with multiple stimulation pulses reduces the overall energy expenditure of cell stimulation when compared to a single pulse stimulation