What might be a consequence of high impedance in pacing leads?

High impedance in pacing leads can lead to an increased risk of failure to capture, which occurs when the pacemaker is unable to sufficiently stimulate the heart to contract. This situation arises because high impedance impedes the effective current delivery from the pacemaker to the myocardium. When impedance is elevated, it indicates that there is a greater resistance to the electrical current flowing through the pacing lead. As a result, the amount of current delivered to the heart muscle may be inadequate, preventing it from responding appropriately to the pacing signals.

Inadequate current flow due to high impedance can result in sporadic or nonexistent heartbeats, leading to symptoms such as dizziness, fatigue, or more severe complications like syncope. Hence, maintaining optimal lead impedance is crucial for effective pacing.

While other outcomes like increased current flow, lower battery consumption, or improved lead longevity may seem plausible, they do not occur with high impedance. Instead, the focus is on the direct relationship between high impedance and the potential risk of failing to capture the heart's contractions effectively.