Voltage clamp simulation of cardiac excitation: field programmable gate array (fpga) implementation

This paper presents the simulation study of voltage clamp technique that enables to analyze current-voltage (I-V) characteristics of ion currents based on Luo-Rudy Phase-I (LR-I) model by using a Field Programmable Gate Array (FPGA). Here, the I-V relationship presents the characterization of each ion channel by a relation between membrane voltage, Vm and resulting channel current. In addition, the voltage clamp technique also allows the detection of single channel currents in biological membranes and is known to be applicable in identifying variety of electrophysiological problems in the cellular level. As computational modeling needs a vast amount of simulation time, a real-time hardware implementation using FPGA could be the solution as it provides high configurability and performance, and able to executes in parallel mode operation for high-performance real-time systems. For rapid prototyping, MATLAB Simulink software that provides a link with the FPGA has been used to design the algorithm. Simulink HDL Coder capable to convert the designed MATLAB Simulink blocks into hardware description language (HDL). As a result, the MATLAB Simulink successfully simulates the voltage clamp of the LR-I excitation model and identifies the I-V characteristics of the ionic currents through Xilinx Virtex-6 XC6VLX240T development board. According to the results of I-V characteristics for six ionic currents in the LR-I model, a fast inward sodium current (INa), a slow inward current (Isi), a timedependent potassium current (IK), a time-independent potassium current (IK1), a time-independent plateau potassium current (IKp) and a background current (Ib), there are two types of current; timedependent and time-independent. The time-independent currents which are the IK1, IKp and Ib have a steady-state I-V relationship and the time-dependent currents which are the INa, Isi and IK often referred to as having a transient I-V relationship but is asymptotic to the steady-state I-V relationship