Why is the first phase of the pulse from a pacemaker cathodic?

  • $\begingroup$ Welcome to Stack Exchange Biology! $\endgroup$
    – L.B.
    Nov 13, 2014 at 20:14
  • 1
    $\begingroup$ Do you have a reference to back this up? In general neural implants are tested to see what the most effective pulse phase is. Often one polarity will stimulate the system, while the other inhibits it.Starting with the stimulating phase is deemed best. Then the opposite phase follows to clear the system from the detrimental effects of charge injection. $\endgroup$
    – AliceD
    Nov 14, 2014 at 0:52
  • $\begingroup$ Hello Chris, thank you for your answer. but still I could not understand why negative peak is important for the stimulation rather than positive peak. As I can understand from electrochemical reactions, for cathodic stimulation, the energy level of free electrons in the metal are raised. It allows to transfer of electrons from metal to reactant species in solution. $\endgroup$
    – Mustakeem
    Nov 15, 2014 at 5:26
  • $\begingroup$ Jan - I don't know which phase is most important either - it depends on the implant system and importantly, on the location of the implant. For example, in retinal implants the active phase depends on whether it is placed sub-retinally (anodic phase most effective) or epi-retinally (cathodic phase most effective). I did a quick search on pace makers and couldn't find anything on it - so please provide me with a citation that says that cathodic-first stimuli are most effective and I'll have a look. Interesting topic! $\endgroup$
    – AliceD
    Nov 24, 2014 at 8:09
  • $\begingroup$ BTW: My answer on a related question may be of help to you: biology.stackexchange.com/questions/22020/… $\endgroup$
    – AliceD
    Nov 24, 2014 at 11:13


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