McKenna's Pharmacology for Nursing, 2e

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P A R T 8  Drugs acting on the cardiovascular system

■■ TABLE 45.2 Types of arrhythmias and drugs of choice for treatment Arrhythmia Antiarrhythmic drugs

Atrial Flutter or fibrillation

Class Ic: flecainide Class III: amiodarone, sotalol

Class IV: diltiazem Other: adenosine Other: digoxin

Paroxysmal atrial tachycardia (PAT) Supraventricular tachycardia (SVT)

Other: digoxin

Class Ic: flecainide, propafenone* Class II: esmolol* (short-term), propranolol Class IV: diltiazem, verapamil (IV) Other: adenosine* (SVT, including those caused by using alternative conduction pathways)

Ventricular Premature ventricular contractions (PVCs)

Class Ib: lignocaine* Class Ib: lignocaine

Tachycardia or fibrillation

Life-threatening ventricular arrhythmias

Class Ia: disopyramide, procainamide Class Ic: flecainide (X), propafenone Class III: amiodarone*, sotalol (X)

*Drug of choice; (X) not drug of choice; proarrhythmic.

leaving the cell, prolonging the action potential and slowing conduction and heart rate. Digoxin is effective in the treatment of atrial arrhythmias. The drug exerts a positive inotropic effect, leading to increased cardiac output, which increases perfusion of the coronary arteries and may eliminate the cause of some arrhyth- mias as hypoxia is resolved and waste products are removed more effectively.

■ ■ Assess cardiac status closely, including pulse, blood pressure, heart rate and rhythm, to identify changes requiring a change in the dosage of the drug or the presence of adverse effects ; auscultate heart sounds, noting any evidence of abnormal sounds, for early detection of heart failure ; and anticipate cardiac monitoring to evaluate heart rate and rhythm and aid in identifying arrhythmia . ■ ■ Monitor respiratory rate and depth, and auscultate lungs, for evidence of adventitious sounds to identify respiratory depression and detect changes associated with heart failure. ■ ■ Inspect abdomen for evidence of distension ; auscultate bowel sounds to evaluate GI motility. ■ ■ Evaluate skin for colour, lesions and temperature to detect adverse reactions and to assess cardiac output . ■ ■ Obtain a baseline ECG to evaluate heart rate and rhythm ; monitor the results of laboratory tests, including full blood count, to identify possible bone marrow suppression , and renal and liver function tests, to determine the need for possible changes in dose and identify toxic effects. Implementation with rationale ■ ■ Titrate the dose to the smallest amount needed to achieve control of the arrhythmia to decrease the risk of severe adverse effects. initiating or changing dose to detect potentially serious adverse effects and to evaluate drug effectiveness. ■ ■ Continually monitor cardiac rhythm when

Care considerations for people receiving antiarrhythmic agents

Assessment: History and examination

■ ■ Assess for contraindications or cautions: any known allergies to these drugs to avoid hypersensitivity reactions ; impaired liver or kidney function, which could alter the metabolism and excretion of the drug ; any condition that could be exacerbated by the depressive effects of the drugs (e.g. heart block, HF, hypotension, shock, respiratory dysfunction, electrolyte disturbances) to avoid exacerbation of these conditions ; and current status of pregnancy and breastfeeding to prevent potential adverse effects on the fetus or baby . ■ ■ Perform a physical assessment to establish a baseline before beginning therapy and during therapy to determine the effectiveness of therapy and evaluate for any potential adverse effects. ■ ■ Assess the person’s neurological status, including level of alertness, speech and vision and reflexes, to identify possible CNS effects .