Bradycardia

Bradycardia refers to a heart rate of less than 60 beats/minute. It occurs normally in young adults, trained athletes, and elderly people as well as during sleep. It's a normal response to vagal stimulation caused by coughing, vomiting, or straining during defecation. When bradycardia results from these causes, the heart rate rarely drops below 40 beats/minute. When it results from pathologic causes (such as cardiovascular disorders), the heart rate may be slower.

By itself, bradycardia is a nonspecific sign. In conjunction with such symptoms as chest pain, dizziness, syncope, and shortness of breath, it can signal a life-threatening disorder.

History and physical examination

After detecting bradycardia, check for related signs of life-threatening disorders. (See Managing severe bradycardia, page 94.)

If the patient's bradycardia isn't accompanied by untoward signs, ask the patient if he or a family member has a history of a slow pulse rate because this may be inherited. Find out if he has an underlying metabolic disorder, such as hypothyroidism, which can precipitate bradycardia. Ask which medications he's taking and if he's complying with the prescribed schedule and dosage. Monitor his vital signs, temperature, pulse, respirations, blood pressure, and oxygen saturation.

Medical causes

Cardiac arrhythmia.Depending on the type of arrhythmia and the patient's tolerance of it, bradycardia may be transient or sustained, benign or life-threatening. Related findings may include hypotension, palpitations, dizziness, weakness, syncope, and fatigue.

Cardiomyopathy.Cardiomyopathy is a potentially life-threatening disorder that may cause transient or sustained bradycardia. Other findings include dizziness, syncope, edema, fatigue, jugular vein distention, orthopnea, dyspnea, and peripheral cyanosis.

Hypothermia.Bradycardia usually appears when the core temperature drops below 89.6° F (32° C). It's accompanied by shivering, peripheral cyanosis, muscle rigidity, bradypnea, and confusion leading to stupor.

Hypothyroidism.Hypothyroidism causes severe bradycardia in addition to fatigue, constipation, unexplained weight gain, and sensitivity to cold. Related signs include cool, dry, thick skin; sparse, dry hair; facial swelling; periorbital edema; thick, brittle nails; and confusion leading to stupor.

Myocardial infarction (MI).Sinus bradycardia is the most common arrhythmia associated with an acute MI. Accompanying signs and symptoms of an MI include an aching, burning, or viselike pressure in the chest that may radiate to the jaw, shoulder, arm, back, or epigastric area; nausea and vomiting; cool, clammy, and pale or cyanotic skin; anxiety; and dyspnea. Blood pressure may be elevated or decreased. Auscultation may reveal abnormal heart sounds.

Other causes

Diagnostic tests.Cardiac catheterization and electrophysiologic studies can induce temporary bradycardia.

Drugs.Beta-adrenergic blockers and some calcium channel blockers, cardiac glycosides, topical miotics (such as pilocarpine), protamine, quinidine and other antiarrhythmics, and sympatholytics may cause transient bradycardia. Failure to take thyroid replacements may cause bradycardia.

Invasive treatments.Suctioning can induce hypoxia and vagal stimulation, causing bradycardia. Cardiac surgery can cause edema or damage to conduction tissues, causing bradycardia.

Nursing considerations

▪ Monitor the patient's vital signs, cardiac rhythm, and level of consciousness frequently.

▪ Prepare the patient for laboratory tests, such as complete blood count; cardiac markers, serum electrolyte, blood glucose, blood urea nitrogen, arterial blood gas, and blood drug levels; and thyroid function tests.

▪ Prepare the patient for a 12-lead electrocardiogram and possibly 24-hour Holter monitoring.

Patient teaching

▪ Inform the patient about signs and symptoms he should report.

▪ Teach him to take his pulse as well as the parameters for calling the practitioner or seeking emergency care.

▪ Provide instructions for care of a permanent pacemaker, if appropriate.

▪ Teach the patient about the cause of his bradycardia and the treatment plan after a diagnosis is established.

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Book Source Details

• Book Title: Nursing: Interpreting Signs and Symptoms
• Author(s): Springhouse
• Year of Publication: 2007
• Copyright Details: Nursing: Interpreting Signs and Symptoms, Copyright © 2007 Lippincott Williams & Wilkins.

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Copyright Details: Nursing: Interpreting Signs and Symptoms, Copyright © 2008 Williams & Wilkins.

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• Back to symptom: Arrhythmia: Introduction (review 234 causes)
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More About This Book: Title: Nursing: Interpreting Signs and Symptoms Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2007 ISBN: 1-58255-668-7

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