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Source: Sanoski CA, Bauman JL. The arrhythmias. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 10th ed. New York, NY: McGraw-Hill; 2017. http://accesspharmacy.mhmedical.com/content.aspx?bookid=1861§ionid=146057036. Accessed March 28, 2017.
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CONDITION/DISORDER SYNONYM
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Usually results from impaired sinoatrial (SA) node function or conduction abnormalities between SA node and atrium, or within AV node or intraventricular conduction pathways.
Sinus bradycardia can be due to heart disease, medications, or normal causes (eg, in trained athletes).
Sick sinus syndrome caused by malfunction of SA node from organic heart disease or normal aging process.
AV block caused by slowed or blocked conduction of electrical impulses in AV conduction system.
β-Blockers, digoxin, or nondihydropyridine calcium antagonists may cause AV block, primarily in AV nodal area.
Vasovagal syncope thought to be neurally mediated process involving stimulation of cardiac mechanoreceptors (Bezold–Jarisch reflex).
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Advancing age.
Hypothyroidism.
Drugs (eg, central α2 agonists, cholinesterase inhibitors, calcium channel blockers, digoxin, lithium, β-blockers)
Heart disease (eg, myocardial infarction)
Electrolyte imbalances.
Sleep apnea.
Head injury.
Hypothermia.
Hypoglycemia.
Toxin exposure.
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CLINICAL PRESENTATION
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Many bradycardias asymptomatic (eg, in trained athletes).
Symptoms associated with hypotension (eg, dizziness, syncope, fatigue, confusion).
Vasovagal syndrome may cause syncope.
If LV dysfunction exists, patients may experience worsening heart failure (HF) symptoms.
Signs: Pulse <60 beats/min in adults.
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DIAGNOSTIC PROCEDURES
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Vagal maneuvers, carotid sinus massage, exercise for AV node bradyarrhythmias.
Electrocardiogram (ECG) findings categorize AV block into first-, second-, or third-degree block.
Holter monitoring (long-term recording) may be used to document the relationship of bradycardia with symptoms.
Electrophysiologic studies may be performed for accurate localization of AV block.
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TREATMENT: GENERAL APPROACH
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TREATMENT: NONPHARMACOLOGIC THERAPY
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Discontinue exacerbating medications, if feasible.
Permanent ventricular pacemaker is long-term treatment of choice for most patients with significant symptoms or those that are drug-refractory.
Temporary ...