A pacemaker is a small, implanted device designed to send electrical impulses to the heart, regulating an abnormally slow heart rhythm. This condition, known as bradycardia, occurs when the heart beats fewer than 60 times per minute in adults, though a slow rate can be normal for highly conditioned athletes. When the heart’s natural electrical system malfunctions, the pacemaker provides the necessary electrical stimulation to maintain a steady rhythm, ensuring the body receives sufficient oxygenated blood.
Identifying Symptoms That Warrant Evaluation
The need for a pacemaker is often signaled by symptoms indicating the body and brain are not receiving enough blood flow due to a slow heart rate. Common complaints include severe fatigue or persistent tiredness, especially during physical activity, which signals insufficient oxygen delivery. This reduced output can also lead to lightheadedness or dizziness.
A more concerning symptom is syncope, or fainting, which occurs when the heart rate drops so low that blood flow to the brain is critically interrupted. Patients may also experience shortness of breath, palpitations (a feeling that the heart is flip-flopping or pounding), or chest pain. Any recurrent or severe symptoms should prompt an immediate consultation with a cardiologist to investigate the underlying cause of the slow heart rate.
Primary Cardiac Conditions Requiring Permanent Implantation
The decision to implant a permanent pacemaker relies on identifying chronic, irreversible conditions that disrupt the heart’s electrical conduction system. The most frequent reasons for permanent pacing are Sinus Node Dysfunction (SND) and high-grade Atrioventricular (AV) block. SND, also called Sick Sinus Syndrome, means the heart’s natural pacemaker is faulty, leading to sustained slow heart rates or long pauses in the rhythm.
A common manifestation of SND is chronotropic incompetence, where the heart cannot appropriately increase its rate during exercise, resulting in exercise intolerance. The other major category is AV block, where electrical signal transmission between the heart’s upper chambers (atria) and lower chambers (ventricles) is delayed or entirely blocked. A pacemaker is strongly indicated for most patients with a third-degree (complete) AV block, where no signals pass from the atria to the ventricles, or a second-degree Mobitz Type II block, which carries a high risk of progressing to a complete block.
These blocks prevent the ventricles from contracting effectively, often causing a slow and unreliable escape rhythm. Pacing is also recommended for patients with symptomatic bradycardia due to atrial fibrillation, where the heart rhythm is too slow despite the underlying chaotic atrial activity. Furthermore, pacing is deemed necessary for certain neuromuscular diseases associated with conduction abnormalities, such as myotonic dystrophy.
Distinguishing Temporary vs. Permanent Pacing
A key distinction in treatment is whether the need for pacing is temporary or permanent, which determines the type of device used. Permanent pacemakers are surgically implanted devices designed for long-term management of chronic conditions like heart block or Sick Sinus Syndrome. They are placed under the skin near the collarbone and provide continuous support for years.
Temporary pacing, however, is used for short-term, acute, and often reversible issues, typically in a hospital setting. Situations requiring a temporary pacemaker include heart rate problems that arise immediately following a heart attack (myocardial infarction) or after open-heart surgery, when the heart’s electrical system may be temporarily stunned. Drug toxicity, such as an overdose of certain heart medications, or severe electrolyte imbalances can also cause acute bradycardia that resolves once the underlying issue is corrected.
Temporary devices, which can be transcutaneous (pads on the skin) or transvenous (a wire inserted into a vein), serve as a bridge to recovery or as an immediate measure until a permanent device can be implanted. The choice between the two depends on whether the patient’s condition is expected to improve and return to a stable rhythm, or if the underlying electrical damage requires lifelong support.
Diagnostic Testing Used to Confirm Need
Before a permanent pacemaker is implanted, diagnostic tests confirm the diagnosis and severity of the bradycardia. The initial test is usually an Electrocardiogram (ECG or EKG), a quick, non-invasive recording of the heart’s electrical signals. This test can immediately identify a very slow rate or a complete block in the conduction system.
Since slow heart rates can be intermittent, a Holter monitor is often used; this portable device is worn for 24 to 48 hours to continuously record heart activity. For rhythms that occur less frequently, event recorders or Zio patches may be used for up to two weeks to capture slow heart rates or pauses. A stress test may also be conducted to check for chronotropic incompetence, measuring the heart’s ability to increase its rate during physical exertion. These tests provide the objective evidence needed to determine if the patient meets clinical guidelines for permanent pacemaker implantation.