High Voltage Pulsed Current (HVPC) is sometimes called ‘Twin Peak Monophasic’ current or Microcurrent therapy. Essentially, this stimulation modality employs a monophasic pulsed current, the pulses being delivered in a doublet (hence the ‘twin peak’ term). Each pulse is of short duration (typically less than 200µs), but, as the name implies, at a high peak voltage (up to 500V, typically 150-500V). By virtue of the fact that each pulse is very short, the current flow through the tissue will average to a very low level – thus the links with microcurrent type therapies. There is evidence for its application in a range of clinical presentations, mainly relating to the stimulation of wound healing, pain relief and facilitated oedema resolution. [1]
A biphasic waveform means that current flows in both directions. It therefore has 2 components (or phases), the positive and the negative components, which represent the changes in current flow. A biphasic waveform is called symmetrical if the portion of the waveform in the first phase is an exact mirror image of, but opposite in direction to, the portion of the waveform in the second phase. An asymmetrical biphasic waveform has 2 phases that are not equal in shape (this type of waveform can further be described as balanced or unbalanced). [4] This type of waveform is more commonly associated with TENS output and is thus more suited to pain modulation rather than tissue repair.
Reference 1, Reference 2, Reference 3, Reference 4: Watson T. Electrotherapy: Evidence Based Practice. Churchill Livingstone Elsevier, 2008. Electrical Stimulation Modalities. Pg 206.
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