Bradycardia Cheat Sheet

Bradycardia Causes of Bradycardia: Bradycardia can result from various underlying factors that disrupt the normal generation or propagation of electrical impulses within the heart. Common causes of bradycardia include: • • • • • Sinus Node Dysfunction: Dysfunction of the sinoatrial (SA) node, the heart's natural pacemaker, can lead to bradycardia. This may occur due to aging, degenerative changes, ischemia, or medications. Heart Block: Heart block refers to impaired conduction of electrical impulses through the heart's conduction system. It can be classified as first-degree, second-degree, or third-degree (complete) heart block, depending on the severity of conduction impairment. Medications: Certain medications, such as beta-blockers, calcium channel blockers, antiarrhythmic drugs, and digoxin, can slow the heart rate and predispose individuals to bradycardia. Hypothyroidism: Thyroid hormone deficiency can lead to bradycardia by affecting the heart's sensitivity to catecholamines and altering myocardial contractility. Electrolyte Imbalances: Abnormal levels of electrolytes such as potassium, calcium, or magnesium can disrupt the heart's electrical activity and contribute to bradycardia. Symptoms of Bradycardia: • Bradycardia may be asymptomatic, particularly in individuals with well-preserved cardiac function. However, when symptoms do occur, they may include: • • • • • • • • • • • Fatigue: Reduced cardiac output and tissue perfusion can lead to fatigue, weakness, and exercise intolerance. Dizziness or Syncope: Inadequate cerebral perfusion due to bradycardia may cause dizziness, lightheadedness, presyncope, or syncope (fainting). Shortness of Breath: Bradycardia can impair cardiac output, leading to dyspnea or exertional breathlessness. Chest Discomfort: Some individuals with bradycardia may experience chest discomfort or angina-like symptoms, particularly during exertion or emotional stress. Palpitations or Pulsations: Awareness of an abnormal heart rhythm or sensations of skipped beats or pauses may occur in some individuals with bradycardia. Diagnosis of Bradycardia: The diagnosis of bradycardia is based on clinical evaluation, including a thorough medical history, physical examination, and assessment of heart rate and rhythm. Additional diagnostic tests may include: Electrocardiogram (ECG): An ECG is the primary diagnostic tool for evaluating heart rhythm and conduction abnormalities. It can identify the presence of bradycardia, heart block, or other rhythm disturbances. Holter Monitoring: Holter monitoring involves continuous ambulatory ECG monitoring over 24-48 hours to assess heart rhythm and capture intermittent arrhythmias. Event Monitoring: Event monitors are similar to Holter monitors but are used for longer periods to capture infrequent or symptomatic arrhythmias. Blood Tests: Blood tests may be performed to evaluate for underlying metabolic or hormonal abnormalities, such as thyroid function tests or electrolyte levels. Management of Bradycardia: • • • • • The management of bradycardia depends on the underlying cause, severity of symptoms, and associated comorbidities. Treatment strategies may include: Observation: Asymptomatic bradycardia without evidence of hemodynamic compromise may not require specific intervention but should be monitored regularly. Medications: Medications such as atropine, isoproterenol, or dopamine may be administered acutely to increase heart rate and improve cardiac output in symptomatic bradycardia. Permanent Pacemaker: Permanent pacemaker implantation is indicated for symptomatic bradycardia refractory to medical therapy or for individuals with high-grade heart block, sinus node dysfunction, or bradycardia-tachycardia syndrome. Treatment of Underlying Causes: Addressing underlying factors contributing to bradycardia, such as electrolyte imbalances, hypothyroidism, or medication adjustments, may be necessary to optimize heart rate and rhythm.