What is a common cause of failure to sense in a pacemaker?

A common cause of failure to sense in a pacemaker is poor electrode contact. For a pacemaker to function effectively, the electrodes must maintain good contact with the myocardial tissue to accurately detect the heart's electrical activity. If the electrode contact is inadequate, the pacemaker may not receive the necessary signals, leading to a failure to sense the intrinsic cardiac activity.

In addition to the issue of poor contact, other factors can contribute to sensing failures, but they don’t address the critical pathway as directly. For example, while excessive lead length and electrode corrosion can impact the overall function of the pacemaker system, they are not as immediate in affecting the sensing mechanism as poor contact is. Pacer settings being too high might alter pacing thresholds or timing but do not directly impede the ability of the pacemaker to sense intrinsic cardiac signals. Therefore, the importance of maintaining proper contact between the electrode and myocardial tissue is paramount for proper sensing and functioning of a pacemaker.