What would you expect to happen if a lead has an insulation break?

When a lead experiences an insulation break, it creates a pathway for current to flow where it shouldn't, which affects the electrical properties of the pacing system. An insulation break generally leads to a decrease in impedance. This is because the impedance, or opposition to current flow, is reduced when the insulation barrier is compromised, allowing more current to flow through the lead. As a result, the current used to stimulate the heart can increase as well.

The significant concern with insulation breaks is that, due to the altered flow of current, there is a potential for loss of capture. Loss of capture occurs when the pacing impulse fails to successfully depolarize the myocardial tissue, meaning that the heart doesn’t respond appropriately to pacing. Therefore, the initial expectation of decreased impedance and increased current coupled with the potential for loss of capture provides a clear understanding of the consequences of an insulation break in pacing leads.