Cardiac arrhythmias

Cardiac arrhythmias: Excerpt from Professional Guide to Diseases (Eighth Edition)

In cardiac arrhythmias (sometimes called cardiac dysrhythmias), abnormal electrical conduction or automaticity changes heart rate and rhythm. (See Normal cardiac conduction, page 1126.) Arrhythmias vary in severity, from those that are mild, asymptomatic, and require no treatment (such as sinus arrhythmia, in which heart rate increases and decreases with respiration) to catastrophic ventricular fibrillation, which necessitates immediate resuscitation. Arrhythmias are generally classified according to their origin (ventricular or supraventricular). Their effect on cardiac output and blood pressure, partially influenced by the origin site, determines their clinical significance. (See Types of cardiac arrhythmias, pages 1127 to 1134.)

Causes

Arrhythmias may be congenital or they may result from one of several factors, including myocardial ischemia, myocardial infarction, or organic heart disease. Drug ingestion (cocaine, amphetamines, caffeine, beta-blockers, psychotropics, sympathomimetics), drug toxicity, or degeneration of the conductive tissue necessary to maintain normal heart rhythm (sick sinus syndrome) can sometimes precipitate arrhythmias. People with imbalances of blood chemistries or those with a history of cardiac conditions (coronary artery disease or heart valve disorders) are at higher risk for developing arrhythmias.

Signs and symptoms

Signs and symptoms of cardiac arrhythmias include palpitations, fainting, light-headedness, dizziness, chest pain, shortness of breath, changes in pulse patterns, paleness, and the temporary absence of breathing. However, the patient with a cardiac arrhythmia may be asymptomatic until the development of sudden cardiac arrest.

Diagnosis

Diagnosis is made by tests that reveal the arrhythmia, such as 12-lead electrocardiography. Ambulatory cardiac monitoring (Holter monitoring), echocardiography, electrophysiology studies, and coronary angiography may also confirm or rule out suspected causes of arrhythmias and help determine treatment.

Special considerations

❑ Assess an unmonitored patient for rhythm disturbances.

❑ If the patient’s pulse is abnormally rapid, slow, or irregular, watch for signs of hypoperfusion, such as altered level of consciousness (LOC), hypotension, and diminished urine output.

❑ Document arrhythmias in a monitored patient, and assess for possible causes and effects.

❑ When life-threatening arrhythmias develop, rapidly assess LOC, respirations, and pulse rate.

❑ Initiate cardiopulmonary resuscitation if indicated.

❑ Evaluate the patient for altered cardiac output resulting from arrhythmias.

❑ Administer medications as ordered and prepare to assist with medical procedures, if indicated (for example, cardioversion).

❑ Monitor for predisposing factors — such as fluid and electrolyte imbalance — and signs of drug toxicity, especially with digoxin. If you suspect drug toxicity, report such signs to the physician immediately and withhold the next dose.

❑ To prevent arrhythmias in a postoperative cardiac patient, provide adequate oxygen and reduce the heart’s workload while carefully maintaining metabolic, neurologic, respiratory, and hemodynamic status.

❑ Consider sedation for transcutaneous pacing if appropriate.

❑ To avoid temporary pacemaker malfunction, install a fresh battery before each insertion. Carefully secure the external catheter wires and the pacemaker box. Assess the threshold daily. Watch closely for premature contractions, a sign of myocardial irritation.

❑ To avert permanent pacemaker malfunction, restrict the patient’s activity after insertion as ordered. Monitor the pulse rate regularly and watch for signs of decreased cardiac output.

❑ If the patient has a permanent pacemaker, warn him about environmental hazards, as indicated by the pacemaker manufacturer. Although hazards may not present a problem, in doubtful situations, 24-hour Holter monitoring may be helpful. Tell the patient to report light-headedness or syncope and stress the importance of regular checkups.

❑ Compare the patient’s cardiac status (pulse, blood pressure, and cardiac output) with the cardiac rhythm before and after treatments.

Pictures

Book Source Details

• Book Title: Professional Guide to Diseases (Eighth Edition)
• Author(s): Springhouse
• Year of Publication: 2005
• Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.

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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.

More About This Book: Title: Professional Guide to Diseases (Eighth Edition) Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2005 ISBN: 1-58255-370-X

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