Chapter 49: Antidysrhythmic Drugs

A nurse administers quinidine sulfate to a pt with atrial fibrillation. The nurse should assess the ECG tracing knowing that quinidine sulfate has what effect on the ECG? A. prolongation of the QT interval B. prolongation of the PR interval C. narrowing of the QRS complex D. tall, peaked T waves

A. Rationale: quinidine sulfate has two pronounced effects on the ECG; widening of the QRS complex and prolongation of the QT interval.

In which part of the conduction pathway in a healthy heart is the electrical impulse delayed to provide time for the blood to fill the ventricles? A. Bundle of His B. AV node C. Purkinje system D. Internodal pathways

B. AV node Rationale: Impulses originate in the SA node and then travel through the AV node to reach the ventricles. The impulse is delayed at the AV node to provide time for the ventricles to fill before they contract.

Adverse effects of verapamil and diltiazem

BRADYCARDIA, hypotension, AV block, heart failure, peripheral edema, constipation, elevated digoxin levels

The nurse is planning care for a patient at risk for dysrhythmias. The nurse understands that the Cardiac Arrhythmia Suppression Trial (CAST) confirmed which finding? A. Most atrial rhythm problems should be treated with medication. B. After a myocardial infarction, all dysrhythmias should be treated. C. Dysrhythmias should be treated only when they are symptomatically significant. D. Most rhythm problems result in bradydysrhythmias.

C. Rationale: The Cardiac Arrhythmia Suppression Trial (CAST) confirmed that all dysrhythmia drugs have prodysrhythmic effects and can worsen existing dysrhythmias and generate new ones. In this study, patients who received encainide and flecainide to prevent rhythm problems after myocardial infarction actually had higher rates of mortality than the control group.

How is lidocaine administered?

IV only

Cardiac dysrhythmias

abnormal rhythm of the heart beat

Dysrhythmias are also known as...

arrythmias

Flecinide and propafenone

block sodium channels, delay ventricular depolarization, and can exacerbate existing dysrhythmias and cause new ones

Lidocaine effects on the heart

blocks sodium channels slowing conduction of the atria, ventricles, and His-purkinje system; reduces automaticity, and accelerates depolarization

Sustained ventricular tachycardia

can have a pulse but not for long or non so CPR will need to be started

Beta blockers for dysrhythmias

decrease HR, BP, cause some vasodilation, and help with ventricular dysrhythmias

Adenosine effects on the heart

decreases automaticity in the SA node, slows down conduction through the AV node, prolongs PR interval

Goal of treatment for all cardiac dysrhythmias

get the HR down, improve ventricular function, and prevent stroke or pulmonary embolus

How is adenosine administered?

given as rapid IV bolus, then flush with saline; administer very close to the entry side of the IV close to the heart

Adverse effects of propanolol

heart block, heart failure, AV block, sinus arrest, hypotension, and bronchospasm in asthmatic pts

Primary indication for digoxin use

heart failure

Amiodarone drug interactions

increases levels and effects of these drugs; quinidine, diltiazem, digoxin, warfarin, and statins (increase levels of these which can cause liver issues)

What occurs when the blood clots during atrial flutter or fibrillation and goes to the lungs?

it can break off and go into the right ventricle to the pulmonary artery causing a pulmonary embolus

4 approved beta blockers for treating dysrhythmias

propanolol, acebutolol, esmolol, and sotalol

Adverse effects of amiodarone

protracted half life, PULMONARY TOXICITY, cardiotoxicity, toxicity in pregnancy and breast feeding, optic neuropathy

Uses for verapamil and diltiazem (calcium channel blockers)

reduce SA node automaticity, delay AV nodal conduction, and reduce myocardial contractility

Amiodarone effects on the heart

reduced automaticity in the SA node, reduced contractility, recused conduction velocity, QRS widening, and prolongation of PR and QT intervals

What occurs when someone receives a toxic dose of lidocaine?

seizures can occur

Adverse effects of adenosine

sinus bradycardia, dyspnea, hypotension, facial flushing, and chest discomfort

Therapeutic uses of verapamil and diltiazem

slow ventricular rate (atrial fibrillation or atrial flutter) and terminate SVT caused by AV nodal reentrant circuit

Quinidine drug class

sodium channel blocker; Class IA antiarrhythmic

Goal of adenosine usage for SVT

terminate and slow down the heart rate

Adverse effects of lidocaine

CNS effects, drowsiness, confusion, and paresthesias

Atria v ventricles in atrial fibrillation

the atria will beat faster than the ventricles so you won't have good cardiac output and the pt will feel fatigue

Why is SVT so dangerous?

the heart is pumping too fast and the ventricles aren't filling as well so you don't have time to perfuse the coronary arteries; there isn't enough energy to produce an effective contraction of the heart

Widowmaker

the main coronary artery gets blocked off and the pt goes into ventricular fibrillation so which we will need to shock them to get the rhythm back to normal

Does premature ventricular complex need to be treated?

these can be normal due to electrolyte issues and don't need to be treated unless the patient is symptomatic

Therapeutic uses of propranolol for dysrhythmias

those caused by excessive sympathetic stimulation and supraventricular tachydysrhythmias

Goal of treatment for SVT (supra ventricular tachycardia)

to get the HR back down; doesn't matter how we do it, just get the HR down below 100 bpm; this will improve ventricular filling and artery perfusion

Therapeutic uses of quinidine

used for supraventricular and ventricular dysrhythmias

Sotalol and Dofetilide

used in helping to stop ventricular dysrhythmias but dofetilide can cause torsades de pointes

Which is the ONLY dysrhythmia lidocaine is used for?

ventricular dysrhythmias; it is not used for supraventricular dysrhythmias, we use beta blockers, calcium channel blockers, adenosine, and digoxin.

Torsades de pointes

ventricular tachycardia where the SA node and AV node aren't working and the ventricle is pumping extremely quickly; have little or no cardiac output

Quinidine effects on the ECG

widens the QRS complex and prolongs the QT interval

The nurse is preparing to administer adenosine to a pt to treat paroxysmal supraventricular tachycardia (SVT). Which action by the nurse is most appropriate? A. inject the medication into the peripheral intravenous (IV) line B. infuse the dose by diluting the drug to 100mL of saline C. administer a small test dose to determine hypersensitivity D. give the medication through the central line catheter

D. Rationale: adenosine is intended for bolus IV administration, it is injected as close to the heart as possible and is followed by a saline flush.

You are administering lidocaine, IV bolus, to a pt with a ventricular dysrhythmia. You monitor the pt for which adverse reactions to lidocaine? A. metabolic alkalosis B. hypertension C. tachycardia D. paresthesias

D. Rationale: High doses of lidocaine may cause numbness and tingling which can lead to seizure activity. High doses can also cause hypotension and bradycardia.

A nurse is caring for a patient receiving dronedarone [Multaq] for treatment of atrial fibrillation. What electrocardiogram (ECG) change indicates an adverse effect of this medication? A. Previously upright T waves now are inverted. B. Previously rounded, upright P waves now are notched. C. ST segments previously on the baseline now are depressed. D. The QT-interval measurement changes from 400 to 520 msec.

D. The QT-interval measurement changes from 400 to 520 msec. Rationale: Dronedarone prolongs the QT interval by about 10 msec. A QT-interval measurement of 400 msec in a normal heart rate (60 to 100 beats/min) is normal. Prolongation to 520 msec would increase the risk of torsades de pointes. Newly inverted T waves and ST-segment depression can be signs of ischemia or infarction and warrant further investigation through analysis of troponin levels. Notched P waves can be a sign of valvular heart disease and are unrelated to treatment with dronedarone.

Supraventricular tachycardia (SVT)

the SA node is not creating the impulse; the P wave is buried, and the T wave is a bump after the QRS

You are caring for a pt taking oral amiodarone to treat atrial fibrillation. Recognizing the adverse effects of this drug, you advise the pt to watch and report which of the following? (select all that apply) A. cough B. blurred vision C. dizziness D. sore throat E. fever

A, B, C, and E Rationale: This drug can cause pulmonary toxicity, manifesting as dyspnea, cough, fever, and chest pain. This drug can also cause blurred vision and photophobia. Other possible effects include dizziness and ataxia and is unlikely to cause a sore throat.

The nurse is administering intravenous lidocaine [Xylocaine] to a patient with a ventricular dysrhythmia. What is the priority nursing intervention to prevent a potential complication with this drug? A. Monitor the electrocardiogram (ECG). B. Obtain a complete blood count. C. Instruct to report any chest pain. D. Keep naloxone [Narcan] at the bedside.

A. Monitor the electrocardiogram (ECG). Rationale: Continuous ECG monitoring is required during lidocaine infusions to evaluate cardiac response and adjust dosage accordingly and detect toxicity. Blood counts are not necessary, because lidocaine is not linked to blood dyscrasias. Lidocaine preferably is given intravenously (IV) rather than intramuscularly (IM). Sudden onset of chest pain is a sign of arterial embolism, which is a possible adverse effect of quinidine, not lidocaine. Naloxone is a reversal agent for opioids and is not used with lidocaine.

What is the most common sustained dysrhythmia among the U.S. population? A. Atrial fibrillation B. Atrial flutter C. Sustained supraventricular tachycardia (SVT) D. Ventricular premature beats (VPBs)

A. atrial fibrillation Rationale: Atrial fibrillation is the most common dysrhythmia, affecting approximately 2.6 million in the United States. This problem not only disrupts cardiac function but also carries a high risk of embolic stroke.

A patient develops supraventricular tachycardia (SVT) and is hypotensive. Which medication should the nurse anticipate will be administered? A. Lidocaine [Xylocaine] B. Adenosine [Adenocard] C. Amiodarone [Cordarone] D. Phenytoin [Dilantin]

B. Adenosine Rationale: The drug of choice for terminating SVT is adenosine. Lidocaine is used for ventricular dysrhythmias; amiodarone is used for atrial and ventricular dysrhythmias; and phenytoin is used for digoxin-induced dysrhythmias.

The nurse is interpreting an electrocardiogram (ECG). Which component represents the depolarization of the ventricles? A. P wave B. QRS complex C. ST segment D. T wave

B. QRS complex Rationale: An electrocardiogram has several components. The P wave is caused by depolarization in the atria; the QRS complex is caused by depolarization of the ventricles; and the T wave is caused by repolarization of the ventricles. The ST segment may be depressed in some clinical conditions.

The nurse is caring for a patient receiving amiodarone [Cordarone]. Which body system should the nurse assess for serious adverse effects of this medication? A. Musculoskeletal B. Respiratory C. Integumentary D. Gastrointestinal

B. Respiratory Rationale: Pulmonary toxicity is the most serious potential adverse effect of amiodarone. It may manifest as pneumonitis or pulmonary fibrosis, with symptoms such as dyspnea, cough, and chest pain.

What should the nurse include in the discharge teaching for a patient prescribed amiodarone [Cordarone]? (Select all that apply.) A. "Take amiodarone with grapefruit juice." B. "Take the medication on an empty stomach." C. "Wear sunblock and protective clothing when you are outdoors." D. "Check your pulse daily and report excessive slowing to your healthcare provider immediately." E. "Immediately notify your healthcare provider of shortness of breath, cough, or chest pain."

C, D, and E Rationale: Patients frequently experience photosensitivity reactions while taking amiodarone. To reduce this risk, patients should avoid sunlamps and wear sunblock and protective clothing when outdoors. Excessive slowing of the heart rate may indicate that the patient is experiencing sinus bradycardia or an AV block. Dyspnea, cough, and chest pain may indicate pulmonary toxicity. Grapefruit juice should be avoided, because it may increase amiodarone levels and thus the risk of toxicity. Gastrointestinal side effects of amiodarone can be reduced by taking the drug on a full stomach.

The nurse is caring for a patient prescribed quinidine [Quinaglute] for a supraventricular dysrhythmia. What is a common adverse effect of this drug? A. Constipation B. Urinary retention C. Diarrhea D. Blurred vision

C. Diarrhea Rationale: Diarrhea and other gastrointestinal problems occur in approximately one third of patients who take quinidine. This is the most common reason patients stop taking the drug.

Which medication is not associated with prolongation of the QT interval? A. Dofetilide [Tikosyn] B. Sotalol [Betapace] C. Diltiazem [Cardizem] D. Dronedarone [Multaq]

C. Diltiazem Rationale: Diltiazem does not prolong the QT interval. Dofetilide, sotalol, and dronedarone prolong the QT interval, putting the patient at risk for torsades de pointes.

The nurse administers an IV infusion of amiodarone to a pt to prevent recurrent episodes of ventricular fibrillation. It is most important for the nurse to assess the pt for which condition? A. urinary retention B. hypercalcemia C. hypotension D. metallic taste

C. hypotension Rationale: The most common adverse effects of IV amiodarone are hypotension and bradydysrhythmias

Adenosine drug interactions

methylxanthings and dipyridamole

How propanolol helps with supraventricular tachydysrhythmias

suppresses excessive discharge and slows ventricular rate

Impulse conduction through the heart

SA node, AV node, bundle of His, 3 left bundles, left ventricle, septum, right bundle, right ventricle

Quinidine effects on the heart

blocks sodium channels, slows impulse condition, delays impulse conduction, and blocks vagal input into the heart

Adverse effects of digoxin

cardiotoxicity (risk increased by hypokalemia)

Premature ventricular complex (PVC)

comes early and interrupts normal sinus rhythm making the heart beat late

Digoxin is also used to treat

supraventricular dysrhythmias (by decreasing conduction through AV node and automaticity in the SA node; QT interval may also be shortened)

Propanalol effects on the heart

decreases automaticity of the SA node, decreased velocity of conduction through the AV node, decreased myocardial contractility

Adverse effects of quinidine (sodium channel blocker- class IA)

diarrhea, cardiotoxicity, arterial embolism, hypersensitivity reactions,

Quinidine drug interactions

digoxin (will intensify the actions of quinidine)

2 fundamental causes of dysrhythmias

disturbance of automaticity in the heart, or a disturbance of conduction (AV block or recirculating activation)

What causes torsades de pointes?

drugs that cause prolongation of the QT interval and can cause ventricular tachycardia

Virtually all drugs that treat dysrhythmias can also cause....

dysrhythmias

Therapeutic uses of adenosine

termination of paroxysmal SVT (narrow complex tachycardia aka SVT)

During SVT what is the difference in the QRS complex?

the QRS complex will be very narrow

How do drugs that help V-tach (torsades de pointes) effect the ECG?

it can prolong the QT interval and make the QRS complex wide (due to the elongated depolarization of the ventricles)

What can occur if a clot breaks off during atrial fib and goes into the left ventricle?

it will clot and go from the left atrium to the left ventricle; going straight through the aorta and to the brain causing a stroke

Why is grapefruit juice contraindicated while taking amiodarone?

levels of the drug can be increased and toxicity can develop

Amiodarone (potassium channel blocker) therapeutic uses

life threatening ventricular dysrhythmias, recurrent ventricular fibrillation, and recurrent hemodynamically unstable ventricular tachycardia

Main treatment for torsades de pointes

magnesium (can also prolong the QT interval)

What is it important to have when giving a pt digoxin?

we must make sure potassium levels are normal because dig needs potassium to work (if we don't have adequate potassium you could have digoxin induced ventricular dysrhythmias)

Why are calcium channel blockers and beta blockers contraindicated with amiodarone?

you can slow down the HR too much

Atrial flutter or fibrillation

you won't see a P wave, QRS is unevenly spaced (blood will recirculate in a circle