What is the effect of high impedance in a pacing system?

High impedance in a pacing system leads to decreased current flow. This occurs because impedance, which is the opposition to the flow of electrical current, increases the resistance in the circuit. When impedance is high, the voltage produced by the pacemaker results in less current being delivered through the pacing lead to the heart tissue.

In simple terms, an increase in impedance means that the pacing system has a harder time pushing electrical current through, which can ultimately affect the effectiveness of stimulation. The pacing threshold may rise, requiring higher voltage from the device to achieve the same level of myocardial depolarization needed for effective heart stimulation. This can lead to issues like loss of capture, where the pacing impulses fail to consistently stimulate the heart, necessitating closer monitoring and potential adjustments to the pacing settings.