If an artificial pacemaker fails, the patient is most likely to experience what symptoms?

In the event of an artificial pacemaker failure, the most common symptoms experienced by the patient are weakness and bradycardia. The primary function of a pacemaker is to maintain an adequate heart rate by delivering electrical impulses to the heart when its own natural pacing system is unable to do so. When a pacemaker fails, the heart may revert to its intrinsic, often slower rhythm, resulting in bradycardia, which is a heart rate of less than 60 beats per minute.

As the heart rate drops, the body's organs may not receive sufficient oxygenated blood, leading to feelings of weakness and fatigue. This lack of proper blood flow can also cause dizziness or lightheadedness. If the bradycardia is severe enough, it can potentially lead to fainting or syncope, illustrating the importance of adequate pacing for maintaining hemodynamic stability.

The other options present symptoms that do not align with the typical physiological responses to pacemaker failure. Each of these symptoms, such as hypertension and headache or irritability with excessive tachycardia, are associated with different cardiovascular conditions or stress responses rather than the direct consequences of pacemaker malfunction.