Dysrhythmia Medications Practice Questions

79 multiple-choice questions on Dysrhythmia medications for paramedic and EMT students, from Chapter 15 (Emergency Medications). Read each question, pick your answer, then tap Show answer to check it and read the explanation.

79 practice questions

1. Adenosine is used for:

   1. A. Stable, regular, narrow-complex SVT
   2. B. Symptomatic bradycardia with AV block
   3. C. Pulseless VT after the first shock
   4. D. Atrial fibrillation with rapid response
   Show answer

   Answer: A. Stable, regular, narrow-complex SVT

   Initial dose is 6 mg rapid IV push, followed by 12 mg if needed.

2. Adenosine 6 mg converts a stable patient's regular narrow-complex SVT, but the SVT returns twice within minutes. What is the most reasonable next drug?

   1. A. Amiodarone 300 mg rapid IV push
   2. B. Diltiazem or a beta blocker IV
   3. C. Adenosine 24 mg rapid IV push
   4. D. Atropine 1 mg IV, repeated
   Show answer

   Answer: B. Diltiazem or a beta blocker IV

   Adenosine acts for seconds, so early recurrence is common; a longer-acting AV nodal blocker (IV diltiazem, verapamil, or a beta blocker) is reasonable for recurrent SVT in a stable patient without hypotension or heart failure. 24 mg is double the largest labeled single dose. Atropine speeds AV conduction and treats bradycardia. A 300-mg rapid push is the pulseless arrest dose and causes hypotension in a perfusing patient.

3. Patients should be warned before adenosine administration because:

   1. A. It causes brief chest pressure, flushing, and a pause
   2. B. It often causes forceful vomiting for several minutes
   3. C. It frequently triggers a generalized seizure
   4. D. It burns intensely at the IV site for an hour
   Show answer

   Answer: A. It causes brief chest pressure, flushing, and a pause

   Forewarning prevents panic during the pause.

4. Atropine for symptomatic bradycardia is dosed at:

   1. A. 0.01 mg/kg IV once, max 0.5 mg
   2. B. 0.5 mg IV every 3–5 minutes, max 3 mg
   3. C. 0.1 mg IV every minute, max 1 mg
   4. D. 1 mg IV every 3–5 minutes, max 3 mg
   Show answer

   Answer: D. 1 mg IV every 3–5 minutes, max 3 mg

   Doses below 0.5 mg can paradoxically slow the heart.

5. Atropine is less likely to work in:

   1. A. Sinus bradycardia with a narrow QRS
   2. B. Wide-complex high-degree AV block
   3. C. Vagally mediated junctional bradycardia
   4. D. Bradycardia caused by suctioning
   Show answer

   Answer: B. Wide-complex high-degree AV block

   Pacing or a chronotropic infusion is preferred there. There the problem is below the AV node.

6. Transcutaneous pacing is indicated when:

   1. A. The rhythm is a stable narrow-complex tachycardia
   2. B. The bradycardic patient is stable and asymptomatic
   3. C. Unstable bradycardia does not respond to atropine
   4. D. The patient declines medication despite normal vitals
   Show answer

   Answer: C. Unstable bradycardia does not respond to atropine

   Sedation should be provided for a conscious patient. Pacing is also used when atropine is inappropriate.

7. Diltiazem is typically used for:

   1. A. Rate control in AF or flutter with RVR
   2. B. Treating refractory VF in cardiac arrest
   3. C. Raising the rate in symptomatic bradycardia
   4. D. Conversion of stable monomorphic VT
   Show answer

   Answer: A. Rate control in AF or flutter with RVR

   Hypotension is a common adverse effect.

8. Calcium channel blockers should be avoided in:

   1. A. Stable atrial fibrillation without pre-excitation
   2. B. Unknown wide-complex tachycardia or WPW with AF
   3. C. Hypertensive patients with rapid atrial flutter
   4. D. Regular narrow-complex SVT after adenosine fails
   Show answer

   Answer: B. Unknown wide-complex tachycardia or WPW with AF

   They can accelerate conduction down an accessory pathway.

9. A 75-kg patient with stable monomorphic VT is receiving a procainamide infusion. What is the maximum total dose for this patient?

   1. A. About 750 mg (10 mg/kg)
   2. B. About 128 mg (1.7 mg/kg)
   3. C. About 1,275 mg (17 mg/kg)
   4. D. About 3,750 mg (50 mg/kg)
   Show answer

   Answer: C. About 1,275 mg (17 mg/kg)

   Procainamide runs at 20 to 50 mg/min until the dysrhythmia stops, hypotension develops, the QRS widens by more than 50%, or a total of 17 mg/kg is given; 75 kg x 17 mg/kg = 1,275 mg. 128 mg is a decimal error. 50 mg/kg confuses the per-minute rate with the ceiling and would be toxic. 10 mg/kg is not the stopping point; the infusion may continue to 17 mg/kg if needed and tolerated.

10. Synchronized cardioversion rather than medication is indicated when:

    1. A. The tachycardic patient is stable and alert
    2. B. The ventricular rate is under 150/min
    3. C. The rhythm is sinus tachycardia from fever
    4. D. The tachycardic patient is unstable
    Show answer

    Answer: D. The tachycardic patient is unstable

    Sedate when time and the patient's condition allow. Instability includes hypotension, altered mental status, chest pain, or shock.

11. A patient with a long QT has recurrent torsades de pointes with a pulse after each pause in a slow rhythm, despite magnesium 2 g. Which next step is most appropriate?

    1. A. Overdrive pacing to raise the heart rate
    2. B. Procainamide at 20 to 50 mg/min
    3. C. Metoprolol 5 mg IV push, repeated
    4. D. Amiodarone 150 mg IV over 10 more minutes
    Show answer

    Answer: A. Overdrive pacing to raise the heart rate

    Pause-dependent torsades with a long QT is suppressed by raising the heart rate, which shortens the QT; temporary overdrive pacing (or isoproterenol as a bridge) is used when magnesium is not enough. Amiodarone and procainamide prolong the QT further and can worsen torsades. A beta blocker slows the rate and lengthens pauses, which is the opposite of what this patient needs.

12. Magnesium sulfate for torsades de pointes with a pulse is given:

    1. A. 1 to 2 g as a rapid undiluted IV push in seconds
    2. B. 1 to 2 g IM divided between both deltoid muscles
    3. C. 5 g diluted, infused over several minutes
    4. D. 1 to 2 g diluted, infused over several minutes
    Show answer

    Answer: D. 1 to 2 g diluted, infused over several minutes

    Rapid administration can cause hypotension.

13. A woman who is 28 weeks pregnant has stable, regular narrow-complex SVT at 190/min that persisted after a modified Valsalva maneuver. Which drug is most appropriate?

    1. A. No drugs until after the delivery
    2. B. Digoxin 0.5 mg IV as the first drug
    3. C. Amiodarone 150 mg over 10 minutes
    4. D. Adenosine 6 mg rapid IV push
    Show answer

    Answer: D. Adenosine 6 mg rapid IV push

    Adenosine is the recommended drug for acute SVT in pregnancy; its seconds-long half-life gives it little effect on the fetus. Amiodarone is avoided in pregnancy when alternatives exist because of fetal thyroid toxicity. Untreated sustained SVT reduces uterine blood flow, so treatment is not deferred. Digoxin is slow to act and is not a first choice for conversion.

14. The first dose of adenosine is:

    1. A. 1 mg/kg rapid IV push with a 5-mL flush
    2. B. 12 mg rapid IV push with a 20-mL flush
    3. C. 6 mg rapid IV push with a 20-mL flush
    4. D. 3 mg slow IV push over 1 to 2 minutes
    Show answer

    Answer: C. 6 mg rapid IV push with a 20-mL flush

    Rapid push and flush are essential due to the ~10-second half-life.

15. A 15-kg child with stable SVT remains in SVT after adenosine 1.5 mg. What second dose is appropriate?

    1. A. 12 mg rapid IV push
    2. B. 0.3 mg rapid IV push
    3. C. 3 mg rapid IV push
    4. D. 1.5 mg rapid IV push
    Show answer

    Answer: C. 3 mg rapid IV push

    The pediatric second dose is 0.2 mg/kg (maximum 12 mg), so 15 kg x 0.2 = 3 mg, given rapidly with a flush. Repeating 1.5 mg repeats a dose that already failed. 12 mg is the adult second dose and the pediatric ceiling, four times this child's dose. 0.3 mg is a tenfold calculation error.

16. A patient with a temperature of 39.8 C has a regular tachycardia at 150/min with a visible P wave before every QRS. The rate drifts with activity. What is the most appropriate treatment?

    1. A. Synchronized cardioversion at 50 J
    2. B. Treat the fever and give fluids
    3. C. Diltiazem 0.25 mg/kg over 2 minutes
    4. D. Adenosine 6 mg rapid IV push
    Show answer

    Answer: B. Treat the fever and give fluids

    A regular rate with P waves before each QRS that varies with activity in a febrile patient is sinus tachycardia, a compensatory response; treat the cause with fluids and fever control. Adenosine only slows it for a moment. Cardioversion cannot convert sinus rhythm and is harmful here. Slowing a compensatory rate with diltiazem can drop the cardiac output and BP.

17. A stable patient has had atrial fibrillation at 140/min for 3 days and takes no anticoagulant. Why is rate control preferred over cardioversion in the field?

    1. A. Cardioversion cannot convert AF
    2. B. Diltiazem prevents future episodes of AF
    3. C. Rate control acts faster than a shock
    4. D. Conversion may dislodge an atrial clot
    Show answer

    Answer: D. Conversion may dislodge an atrial clot

    Atrial fibrillation lasting more than about 48 hours can form a clot in the left atrium, and restoring sinus rhythm without anticoagulation or imaging can send it to the brain, so a stable patient gets rate control. A shock acts in seconds, faster than any drug. Cardioversion can convert AF; the problem is the stroke risk. Diltiazem controls the rate but does not prevent recurrence.

18. Lidocaine 1.5 mg/kg converts a patient's stable monomorphic VT. Per many protocols, which maintenance infusion follows?

    1. A. 4 to 8 mg/kg/min
    2. B. 0.1 to 0.4 mg/min
    3. C. 10 to 40 mg/min
    4. D. 1 to 4 mg/min
    Show answer

    Answer: D. 1 to 4 mg/min

    After a lidocaine bolus works, a maintenance infusion of 1 to 4 mg/min (reduced in older adults and in heart or liver failure) keeps levels up. 10 to 40 mg/min is tenfold too high and would cause seizures. Dosing at 4 to 8 mg/kg/min would be hundreds of milligrams per minute in an adult. 0.1 to 0.4 mg/min is tenfold too low to have an effect.

19. A patient with stable SVT has known sick sinus syndrome and no pacemaker. What is the main concern with giving adenosine?

    1. A. A prolonged sinus pause or asystole
    2. B. An onset delayed by about 10 minutes
    3. C. Sustained severe hypertension
    4. D. Rebound hypoglycemia
    Show answer

    Answer: A. A prolonged sinus pause or asystole

    Adenosine depresses the sinus and AV nodes, so in sick sinus syndrome or second- or third-degree block without a working pacemaker it can cause a long pause or asystole; it is contraindicated there. It causes brief flushing and sometimes a short drop in BP, not sustained hypertension. It does not affect glucose. Its onset is within seconds.

20. Pediatric adenosine first dose is:

    1. A. 0.2 mg/kg (max 12 mg)
    2. B. 1 mg/kg (max 12 mg)
    3. C. 0.05 mg/kg (max 3 mg)
    4. D. 0.1 mg/kg (max 6 mg)
    Show answer

    Answer: D. 0.1 mg/kg (max 6 mg)

    Second dose is 0.2 mg/kg (max 12 mg).

21. Adenosine should be avoided in:

    1. A. Irregular wide-complex tachycardia and severe asthma
    2. B. Anyone who drank coffee within the past day
    3. C. Regular narrow-complex SVT in otherwise healthy adults
    4. D. Infants and children with stable, regular SVT
    Show answer

    Answer: A. Irregular wide-complex tachycardia and severe asthma

    In WPW with AF, AV blockade can accelerate conduction down the accessory pathway.

22. Five minutes after IV diltiazem for atrial fibrillation, the heart rate is 112/min, but the BP has fallen from 128/80 to 78/50. What is the most appropriate response?

    1. A. Fluid bolus; consider IV calcium
    2. B. Repeat diltiazem at 0.35 mg/kg now
    3. C. Give metoprolol 5 mg IV push
    4. D. Give adenosine 12 mg rapid push
    Show answer

    Answer: A. Fluid bolus; consider IV calcium

    Hypotension is diltiazem's most common adverse effect; a fluid bolus is the first step, and IV calcium can reverse calcium channel blocker hypotension. A repeat diltiazem dose would deepen the hypotension. Adding metoprolol stacks two AV nodal blockers and worsens BP and rate. Adenosine has no role and would not reverse the drug.

23. An 80-year-old with vomiting for 3 days has a temperature of 38.9 C, dry mucous membranes, AF at 140/min, and a BP of 92/60. Your partner wants to give diltiazem. What is best?

    1. A. Diltiazem 0.25 mg/kg IV over 2 min
    2. B. Metoprolol 5 mg IV every 5 minutes, x 3
    3. C. Treat the dehydration and fever first
    4. D. Adenosine 6 mg rapid IV push
    Show answer

    Answer: C. Treat the dehydration and fever first

    The fast rate here is largely a response to fever and volume loss; fluids and fever control often slow it, and an AV nodal blocker in a dry, borderline-hypotensive patient can cause severe hypotension. Metoprolol carries the same risk. Adenosine does not convert AF and only slows it for seconds.

24. Diltiazem is contraindicated in:

    1. A. Hypotension, WPW with AF, or decompensated heart failure
    2. B. Patients with a history of asthma or COPD
    3. C. Stable atrial fibrillation with a ventricular rate over 120
    4. D. Patients with a long history of hypertension
    Show answer

    Answer: A. Hypotension, WPW with AF, or decompensated heart failure

    Negative inotropy and vasodilation worsen these conditions. Wide-complex tachycardia of unknown origin is also a contraindication. Diltiazem is often chosen over beta blockers in asthma or COPD, and a history of hypertension is no barrier when the current BP is adequate.

25. A patient with a pulse has polymorphic VT at 230/min, a BP of 70/30, and confusion. What is the most appropriate treatment?

    1. A. Adenosine 6 mg rapid IV push
    2. B. Amiodarone 150 mg over 10 minutes
    3. C. Unsynchronized shock (defibrillation)
    4. D. Synchronized cardioversion at 50 J first
    Show answer

    Answer: C. Unsynchronized shock (defibrillation)

    Unstable polymorphic VT is treated like VF with an unsynchronized high-energy shock, because the varying QRS shapes keep the monitor from synchronizing and a delayed or failed sync wastes time. Low-energy synchronized cardioversion is for regular rhythms. Adenosine has no role in VT of this type. A 10-minute infusion is for stable monomorphic VT and is too slow here.

26. Procainamide for stable monomorphic VT is given at:

    1. A. 100 mg/min until the QRS narrows, max 30 mg/kg
    2. B. 5 mg/kg IV push, repeated every 10 minutes
    3. C. 1 g rapid IV push, then 500 mg every 5 minutes
    4. D. 20–50 mg/min until an endpoint, max 17 mg/kg
    Show answer

    Answer: D. 20–50 mg/min until an endpoint, max 17 mg/kg

    Procainamide requires careful monitoring for QRS widening and hypotension. Endpoints are arrhythmia suppression, hypotension, QRS widening over 50%, or the 17 mg/kg maximum.

27. Lidocaine for stable VT with a pulse is dosed at:

    1. A. 3 mg/kg once, then 1 mg/kg every 5–10 minutes
    2. B. 0.1 mg/kg, then 0.05 mg/kg, max 1 mg/kg
    3. C. 300 mg IV push, then 150 mg every 10 minutes
    4. D. 1–1.5 mg/kg, then 0.5–0.75 mg/kg, max 3 mg/kg
    Show answer

    Answer: D. 1–1.5 mg/kg, then 0.5–0.75 mg/kg, max 3 mg/kg

    Follow with an infusion of 1–4 mg/min if effective. Repeat doses are given every 5 to 10 minutes.

28. A patient with an acute MI has occasional unifocal PVCs, a BP of 136/84, and no symptoms from them. What is the role of lidocaine?

    1. A. Not given; monitor and treat ischemia
    2. B. A 2 mg/min infusion throughout transport
    3. C. A 1 mg/kg bolus before each PVC run
    4. D. A 1.5 mg/kg bolus to prevent VF
    Show answer

    Answer: A. Not given; monitor and treat ischemia

    Prophylactic lidocaine for PVCs in acute MI is no longer recommended; it did not lower mortality and may raise it through bradycardia and asystole. Treat the ischemia, correct hypoxia and electrolytes, and watch the monitor. A preventive bolus, a prophylactic infusion, or doses timed to PVCs all expose the patient to toxicity without benefit.

29. A peripheral dopamine infusion infiltrates, and the skin around the site is pale and cold. After stopping the infusion, which antidote may be infiltrated into the area per the drug label?

    1. A. Hyaluronidase
    2. B. Naloxone
    3. C. Atropine
    4. D. Phentolamine
    Show answer

    Answer: D. Phentolamine

    Phentolamine, an alpha blocker, is infiltrated into the area to reverse the alpha-mediated vasoconstriction from extravasated dopamine or norepinephrine and prevent necrosis. Naloxone reverses opioids. Atropine blocks muscarinic receptors and does not affect vasoconstriction. Hyaluronidase is used for some non-vasopressor extravasations to spread the fluid, not to reverse vasoconstriction.

30. A COPD patient with an SpO2 of 84% and wheezing has an irregular narrow-complex tachycardia at 130/min with three or more different P-wave shapes. What is the most appropriate treatment?

    1. A. Synchronized cardioversion at 100 J
    2. B. Treat the hypoxia and bronchospasm
    3. C. Adenosine 6 mg, then 12 mg
    4. D. Amiodarone 300 mg rapid IV push
    Show answer

    Answer: B. Treat the hypoxia and bronchospasm

    Multifocal atrial tachycardia (three or more P-wave shapes) is usually driven by hypoxia and lung disease, so treating the underlying cause controls it. Cardioversion does not work on this automatic rhythm. Adenosine does not convert it. A 300-mg rapid push is the arrest dose and is not used in a patient with a pulse.

31. A heart transplant recipient has symptomatic sinus bradycardia at 40/min with a BP of 80/50. Which drug is the most appropriate choice?

    1. A. Adenosine 3 mg rapid IV push
    2. B. Metoprolol 5 mg IV push
    3. C. Atropine 1 mg, repeated to 3 mg
    4. D. Epinephrine infusion, titrated
    Show answer

    Answer: D. Epinephrine infusion, titrated

    A transplanted heart has no vagal innervation, so atropine is unlikely to work; a direct-acting chronotropic infusion such as epinephrine (or isoproterenol) or pacing is used. Adenosine slows the heart and is used for SVT. Metoprolol would slow the rate further.

32. A 3-kg infant has bradycardia with poor perfusion from increased vagal tone during suctioning. Under current PALS guidance, what atropine dose is appropriate?

    1. A. 0.1 mg IV/IO, the minimum dose
    2. B. 0.06 mg IV/IO (0.02 mg/kg)
    3. C. 0.6 mg IV/IO (0.2 mg/kg)
    4. D. 0.006 mg IV/IO (0.002 mg/kg)
    Show answer

    Answer: B. 0.06 mg IV/IO (0.02 mg/kg)

    Pediatric atropine is 0.02 mg/kg IV/IO, so 3 kg x 0.02 = 0.06 mg. The 2020 AHA PALS update removed the old 0.1-mg minimum dose because paradoxical bradycardia at low doses was not supported and the floor overdosed small infants; the maximum single dose remains 0.5 mg. 0.6 mg is a tenfold overdose above the maximum, and 0.006 mg is a tenfold underdose.

33. A 20-kg child has a stable, regular wide-complex tachycardia, and expert consultation advises amiodarone. Which dose and rate are appropriate?

    1. A. 100 mg rapid IV push
    2. B. 300 mg over 10 minutes
    3. C. 20 mg IV over 20 to 60 minutes
    4. D. 100 mg over 20 to 60 minutes
    Show answer

    Answer: D. 100 mg over 20 to 60 minutes

    For a child with a pulse and stable wide-complex tachycardia, PALS gives amiodarone 5 mg/kg over 20 to 60 minutes (20 kg x 5 = 100 mg), with expert consultation. A rapid push is the pulseless arrest technique and causes hypotension in a perfusing child. 300 mg is an adult dose. 20 mg is only 1 mg/kg.

34. Epinephrine infusion for bradycardia unresponsive to atropine is:

    1. A. 2–10 mcg/min titrated
    2. B. 1 mg IV bolus repeated
    3. C. 0.1 mg/kg/min titrated
    4. D. 100 mcg/min titrated
    Show answer

    Answer: A. 2–10 mcg/min titrated

    Chronotropic infusion is an alternative to pacing.

35. Dopamine infusion for bradycardia is dosed at:

    1. A. 50–100 mcg/kg/min
    2. B. 5–20 mcg/kg/min
    3. C. 1–5 mg/kg/min
    4. D. 1–2 mcg/kg/min
    Show answer

    Answer: B. 5–20 mcg/kg/min

    Dopamine at these rates provides beta-1 and alpha effects.

36. Beta blockers such as metoprolol for rate control are contraindicated in:

    1. A. Hypotension, heart failure, or asthma
    2. B. Stable angina in a patient with a prior MI
    3. C. Hypertension with sinus tachycardia above 100
    4. D. Stable atrial fibrillation with a rate above 120
    Show answer

    Answer: A. Hypotension, heart failure, or asthma

    Negative inotropic and bronchoconstrictive effects limit use. High-degree AV block is also a contraindication. The heart failure is acute decompensated failure, and the asthma severe.

37. Metoprolol IV dose for rate control is:

    1. A. 50 mg IV push, repeated once if needed
    2. B. 0.5 mg IV over 2–5 minutes, up to 3 doses
    3. C. 5 mg IV over 2–5 minutes, up to 3 doses
    4. D. 25 mg rapid IV push as a single dose
    Show answer

    Answer: C. 5 mg IV over 2–5 minutes, up to 3 doses

    Monitor BP and heart rate between doses.

38. A stable patient with known WPW has a regular, narrow-complex tachycardia at 200/min. Regarding adenosine:

    1. A. It may be used with a defibrillator ready
    2. B. It must be given as 24 mg to be effective
    3. C. It should be pushed slowly over 2 minutes
    4. D. It is contraindicated with WPW history
    Show answer

    Answer: A. It may be used with a defibrillator ready

    A regular narrow-complex tachycardia in WPW is usually orthodromic AVRT, which runs down the AV node, so vagal maneuvers and adenosine are recommended; adenosine can occasionally trigger atrial fibrillation, so a defibrillator should be ready. It is avoided in irregular or pre-excited (wide) AF, not in this regular narrow rhythm. 24 mg exceeds the labeled maximum, and a slow push lets adenosine be metabolized before it reaches the heart.

39. Verapamil may be used for SVT but is contraindicated in:

    1. A. Narrow-complex SVT after adenosine fails
    2. B. Patients with WPW who are in sinus rhythm
    3. C. Patients with asthma or other reactive airway disease
    4. D. Wide-complex tachycardia, hypotension, infants
    Show answer

    Answer: D. Wide-complex tachycardia, hypotension, infants

    Verapamil in VT or infants can cause cardiovascular collapse. Verapamil is an option for regular narrow-complex SVT when adenosine fails, and asthma is a reason to avoid beta blockers, not calcium channel blockers.

40. A patient with known hyperthyroidism has fever, agitation, and atrial fibrillation at 160/min with a BP of 150/80. Which rate-control drug class is generally favored?

    1. A. Digoxin as the sole rate-control drug
    2. B. Atropine 1 mg IV, repeated
    3. C. Adenosine, repeated as needed
    4. D. A beta blocker such as propranolol
    Show answer

    Answer: D. A beta blocker such as propranolol

    Thyroid storm drives the heart through excess adrenergic sensitivity, so a beta blocker (propranolol is classic) both slows the rate and blunts the adrenergic symptoms. Adenosine does not convert AF. Digoxin works poorly in high-output thyrotoxic states. Atropine raises the heart rate.

41. A stable patient with SVT has a central venous catheter as the only access. How is the first adenosine dose usually adjusted?

    1. A. Doubled to 12 mg through the line
    2. B. Reduced to 3 mg through the line
    3. C. Given IM, since the line is central
    4. D. Unchanged, but pushed over 1 minute
    Show answer

    Answer: B. Reduced to 3 mg through the line

    Adenosine given through a central line reaches the heart almost undiluted, so ACLS guidance reduces the first dose to 3 mg (as for transplant recipients and patients on dipyridamole or carbamazepine). Doubling the dose risks prolonged asystole. Adenosine is not given IM. A slow push lets it be metabolized before it acts.

42. Ibutilide is a drug used for:

    1. A. Treating asystole after epinephrine has failed
    2. B. Increasing the rate in symptomatic bradycardia
    3. C. Converting atrial fibrillation or flutter
    4. D. Treating shock-refractory VF in cardiac arrest
    Show answer

    Answer: C. Converting atrial fibrillation or flutter

    Ibutilide is a Class III agent with torsades risk. It is used for pharmacologic cardioversion in the hospital.

43. How is the modified Valsalva maneuver performed for stable SVT?

    1. A. Press firmly on both closed eyes for 30 s
    2. B. Massage both carotid arteries together
    3. C. Strain 15 s, then lie flat with legs raised
    4. D. Hold the breath for 60 seconds while standing
    Show answer

    Answer: C. Strain 15 s, then lie flat with legs raised

    In the REVERT method the semi-recumbent patient strains (for example, blowing into a 10-mL syringe) for 15 seconds, then is laid flat with the legs raised to 45 degrees for 15 seconds; this roughly tripled conversion over a standard Valsalva. Breath holding while standing gives a weak vagal effect. Eyeball pressure can injure the eye and is not used. Massaging both carotids at once can cause cerebral ischemia; carotid massage is done on one side only, and is avoided in older patients and those with bruits.

44. In stable SVT when adenosine fails, the next options include:

    1. A. Atropine 1 mg IV, repeated every 3 to 5 min
    2. B. An epinephrine infusion at 2–10 mcg/min
    3. C. Lidocaine 1 to 1.5 mg/kg by slow IV push
    4. D. A calcium channel blocker or beta blocker
    Show answer

    Answer: D. A calcium channel blocker or beta blocker

    AV nodal blockers are second-line for SVT.

45. Vagal maneuvers before adenosine include:

    1. A. Firm bilateral pressure on the closed eyeballs
    2. B. Carotid massage in all patients regardless of age
    3. C. A firm precordial thump to the lower sternum
    4. D. Modified Valsalva, or ice to the face in infants
    Show answer

    Answer: D. Modified Valsalva, or ice to the face in infants

    The modified Valsalva has the highest success rate; carotid massage is avoided in patients with bruits or at risk for stroke. The modified Valsalva is a strain followed by a passive leg raise.

46. An infant has a heart rate of 240/min. Which finding most favors SVT rather than sinus tachycardia?

    1. A. A rate that slows with calming
    2. B. Visible P waves before each QRS
    3. C. A fixed rate with no visible P waves
    4. D. A history of fever, vomiting, and poor intake
    Show answer

    Answer: C. A fixed rate with no visible P waves

    Infant SVT usually runs above 220/min at a fixed rate, starts abruptly, and has absent or abnormal P waves. Fever, vomiting, a rate that varies with activity or calming, and normal P waves before each QRS all point to sinus tachycardia, which is treated by fixing the cause rather than with adenosine.

47. The maximum cumulative dose of amiodarone in 24 hours is:

    1. A. 2.2 g
    2. B. 3.5 g
    3. C. 900 mg
    4. D. 1.2 g
    Show answer

    Answer: A. 2.2 g

    Includes boluses and infusion.

48. A 50-year-old heart transplant recipient has stable narrow-complex SVT at 180/min. What is the most appropriate initial adenosine dose?

    1. A. 3 mg rapid IV push
    2. B. 12 mg rapid IV push
    3. C. 6 mg rapid IV push
    4. D. 0.1 mg/kg slow IV push
    Show answer

    Answer: A. 3 mg rapid IV push

    Denervated transplanted hearts are supersensitive to adenosine, so the initial dose is reduced to 3 mg.

49. After 6 mg of adenosine, the monitor briefly slows and reveals sawtooth waves at 300/min before the tachycardia at 150/min resumes. This indicates:

    1. A. Ventricular tachycardia needing immediate defibrillation
    2. B. Successful conversion that needs no further treatment
    3. C. Adenosine toxicity that should be reversed with calcium
    4. D. Atrial flutter, which adenosine unmasked but will not convert
    Show answer

    Answer: D. Atrial flutter, which adenosine unmasked but will not convert

    Adenosine's transient AV block can reveal flutter or atrial tachycardia; it does not terminate rhythms that do not depend on the AV node.

50. A 10-kg infant with stable SVT has only an IO line in the tibia. How should adenosine be given?

    1. A. 10 mg through the IO, slowly over 1 min
    2. B. 1 mg through the IO with a rapid flush
    3. C. 1 mg IM into the lateral thigh
    4. D. Wait for an IV; the IO cannot be used
    Show answer

    Answer: B. 1 mg through the IO with a rapid flush

    Adenosine can be given IV or IO at 0.1 mg/kg (10 kg x 0.1 = 1 mg), pushed rapidly and followed at once by a flush. Waiting for an IV delays treatment when IO access works. 10 mg is a tenfold overdose, and a slow push lets the drug be metabolized before it acts. Adenosine is not given IM.

51. A 12-kg toddler has SVT at 280/min, is lethargic with a capillary refill of 5 seconds, and has no vascular access. What is the most appropriate treatment?

    1. A. Adenosine 1.2 mg IM into the lateral thigh
    2. B. Oral diltiazem crushed and given by mouth
    3. C. Unsynchronized defibrillation at 4 J/kg
    4. D. Synchronized cardioversion at 0.5 to 1 J/kg
    Show answer

    Answer: D. Synchronized cardioversion at 0.5 to 1 J/kg

    Unstable pediatric SVT without immediate IV/IO access is treated with synchronized cardioversion starting at 0.5 to 1 J/kg.

52. A 75-kg man in atrial fibrillation at 156/min has a BP of 128/80 and no history of heart failure. What is the appropriate initial diltiazem dose?

    1. A. About 20 mg IV over 2 minutes
    2. B. 5 mg IV push every minute
    3. C. 75 mg IV over 2 minutes
    4. D. 2 mg IV as a rapid push
    Show answer

    Answer: A. About 20 mg IV over 2 minutes

    Diltiazem is dosed at 0.25 mg/kg (commonly 15 to 20 mg) given over 2 minutes.

53. Fifteen minutes after diltiazem 20 mg, the 75-kg patient in atrial fibrillation still has a rate of 140/min and a stable BP. What repeat dose is appropriate?

    1. A. About 75 mg IV over 2 minutes (1 mg/kg)
    2. B. About 25 mg IV over 2 minutes (0.35 mg/kg)
    3. C. About 50 mg IV over 2 minutes (0.7 mg/kg)
    4. D. About 5 mg IV over 2 minutes (0.07 mg/kg)
    Show answer

    Answer: B. About 25 mg IV over 2 minutes (0.35 mg/kg)

    The second diltiazem dose is 0.35 mg/kg, commonly 20 to 25 mg, after 15 minutes if needed.

54. A patient with a known ejection fraction of 20% has atrial fibrillation at 150/min, crackles, and a BP of 104/70. Which IV rate-control drug is reasonable?

    1. A. Diltiazem 0.25 mg/kg
    2. B. Verapamil 5 mg
    3. C. Amiodarone (or digoxin)
    4. D. Metoprolol 15 mg rapid push
    Show answer

    Answer: C. Amiodarone (or digoxin)

    In AF with decompensated heart failure and reduced ejection fraction, IV amiodarone or digoxin is reasonable for rate control because neither has much negative inotropic effect. Diltiazem and verapamil depress contractility and can worsen pulmonary edema and hypotension. A rapid 15-mg push of metoprolol is a negative inotrope given too fast for this patient.

55. A 28-year-old with known WPW has a stable, irregular, very fast wide-complex tachycardia with varying QRS shapes. Which treatment is most appropriate?

    1. A. Metoprolol 5 mg IV every 5 minutes, up to 3 doses
    2. B. Diltiazem 0.25 mg/kg IV over 2 minutes
    3. C. Procainamide or expert-guided cardioversion
    4. D. Adenosine 6 mg rapid IV push with a flush
    Show answer

    Answer: C. Procainamide or expert-guided cardioversion

    In pre-excited atrial fibrillation, AV nodal blockers can speed conduction down the accessory pathway and cause VF. Procainamide is given as an infusion.

56. A 66-year-old has a regular, monomorphic wide-complex tachycardia at 170/min, a BP of 124/78, and is alert. Which antidysrhythmic regimen is appropriate?

    1. A. Amiodarone 300 mg rapid IV push
    2. B. Diltiazem 20 mg IV over 2 minutes
    3. C. Amiodarone 150 mg IV over 10 minutes
    4. D. Lidocaine 3 mg/kg rapid IV push
    Show answer

    Answer: C. Amiodarone 150 mg IV over 10 minutes

    Stable VT with a pulse is treated with amiodarone 150 mg over 10 minutes, which can be repeated; 300 mg push is the arrest dose.

57. During a procainamide infusion for stable VT, which finding should make you stop the infusion?

    1. A. The QRS widens by more than 50% from baseline
    2. B. The patient reports fewer palpitations
    3. C. The heart rate decreases from 170 to 140/min
    4. D. The systolic BP rises from 120 to 130 mm Hg
    Show answer

    Answer: A. The QRS widens by more than 50% from baseline

    Procainamide is stopped when the rhythm is suppressed, hypotension develops, the QRS widens over 50%, or 17 mg/kg has been given.

58. Which patient with stable monomorphic VT should NOT receive procainamide?

    1. A. One whose VT rate is 160 beats per minute
    2. B. One with a stable BP of 130/80 mm Hg and alert
    3. C. One with prolonged QT or heart failure
    4. D. A 40-year-old with no prior medical history
    Show answer

    Answer: C. One with prolonged QT or heart failure

    Procainamide prolongs the QT and has negative inotropic effects, so it is avoided in prolonged QT and congestive heart failure.

59. A 48-year-old on methadone with a QTc of 610 ms has runs of polymorphic VT with a pulse and a BP of 110/70. Which drug is most appropriate?

    1. A. Procainamide 20 to 50 mg/min IV infusion
    2. B. Amiodarone 300 mg rapid IV push, then 150 mg
    3. C. Magnesium 1 to 2 g IV over several minutes
    4. D. Adenosine 6 mg rapid IV push, then 12 mg
    Show answer

    Answer: C. Magnesium 1 to 2 g IV over several minutes

    Torsades de pointes with a pulse is treated with magnesium; amiodarone and procainamide prolong the QT further. The drug is magnesium sulfate.

60. A 70-year-old has sinus bradycardia at 38/min, a BP of 76/40, diaphoresis, and confusion. What is the first-line drug?

    1. A. Atropine 0.1 mg IV, repeated every minute to 1 mg
    2. B. Atropine 1 mg IV, repeated every 3 to 5 minutes to 3 mg
    3. C. Amiodarone 150 mg IV over 10 minutes
    4. D. Adenosine 6 mg rapid IV push with a flush
    Show answer

    Answer: B. Atropine 1 mg IV, repeated every 3 to 5 minutes to 3 mg

    Current ACLS atropine dosing for symptomatic bradycardia is 1 mg every 3 to 5 minutes, maximum 3 mg.

61. A patient in third-degree AV block with a wide ventricular escape rhythm at 30/min is hypotensive. Atropine 1 mg had no effect. What is the next step?

    1. A. A second atropine dose, then wait 10 minutes
    2. B. Adenosine 12 mg to reset AV node conduction
    3. C. Transcutaneous pacing or an epinephrine infusion
    4. D. Lidocaine 1 mg/kg to stabilize the escape focus
    Show answer

    Answer: C. Transcutaneous pacing or an epinephrine infusion

    Infranodal block rarely responds to atropine; pacing or a chronotropic infusion such as epinephrine or dopamine is used. Epinephrine is infused at 2 to 10 mcg/min.

62. A post-MI patient has an accelerated idioventricular rhythm at 50/min with a BP of 110/70. Why would giving lidocaine be dangerous?

    1. A. It interacts with aspirin to cause major bleeding
    2. B. It may suppress the only functioning ventricular pacemaker
    3. C. It causes a rapid and severe rise in serum potassium
    4. D. It converts the rhythm into an unstable SVT
    Show answer

    Answer: B. It may suppress the only functioning ventricular pacemaker

    Ventricular escape rhythms are protective; suppressing them with lidocaine can leave the patient in asystole.

63. Procainamide 1 g is mixed in 250 mL. What pump rate delivers 20 mg/min?

    1. A. 1,200 mL/h
    2. B. 30 mL/h
    3. C. 80 mL/h
    4. D. 300 mL/h
    Show answer

    Answer: D. 300 mL/h

    The concentration is 1,000 mg / 250 mL = 4 mg/mL. 20 mg/min / 4 mg/mL = 5 mL/min, and 5 mL/min x 60 = 300 mL/h. 30 mL/h is a tenfold error. 80 mL/h results from multiplying 20 by 4 instead of dividing. 1,200 mL/h multiplies the dose by 60 without dividing by the concentration.

64. Diltiazem 125 mg is mixed to a total of 125 mL. What pump rate delivers 10 mg/h?

    1. A. 1 mL/h
    2. B. 10 mL/h
    3. C. 100 mL/h
    4. D. 12.5 mL/h
    Show answer

    Answer: B. 10 mL/h

    125 mg in 125 mL is 1 mg/mL, so 10 mg/h needs 10 mL/h (the label's usual maintenance range is 5 to 15 mg/h). 1 mL/h and 100 mL/h are tenfold errors. 12.5 mL/h divides the bag volume by 10 rather than the dose by the concentration.

65. A patient has second-degree AV block type I (Wenckebach) at 52/min, a BP of 128/76, and no symptoms. Which treatment is indicated?

    1. A. Transcutaneous pacing at 70 mA
    2. B. Atropine 1 mg IV, repeated to 3 mg
    3. C. No drug; monitor and transport
    4. D. Epinephrine infusion at 2 mcg/min
    Show answer

    Answer: C. No drug; monitor and transport

    Bradycardia is treated only when it causes symptoms or poor perfusion; an asymptomatic patient with Wenckebach and a normal BP needs monitoring and transport. Atropine, an epinephrine infusion, and pacing are for symptomatic bradycardia and add risk without benefit here.

66. During an amiodarone infusion for stable VT, the BP drops from 128/80 to 84/50. What is the most likely cause and action?

    1. A. Amiodarone-related vasodilation; slow or stop the infusion
    2. B. Anaphylaxis; give epinephrine 0.5 mg IM
    3. C. An expected effect; increase the infusion rate
    4. D. Hyperkalemia; give calcium chloride 1 g IV
    Show answer

    Answer: A. Amiodarone-related vasodilation; slow or stop the infusion

    Hypotension is the most common adverse effect of IV amiodarone and is rate-related.

67. A patient in atrial fibrillation with a rapid rate has severe asthma requiring frequent albuterol. Which rate-control drug should be avoided?

    1. A. Metoprolol
    2. B. Diltiazem
    3. C. Digoxin
    4. D. Amiodarone
    Show answer

    Answer: A. Metoprolol

    Beta blockers such as metoprolol can provoke bronchospasm in reactive airway disease and blunt the effect of albuterol, so they are avoided here. Diltiazem controls the rate without causing bronchospasm and is usually preferred if the BP allows. Digoxin is safe for the airways but slow to act. Amiodarone is an option, especially with heart failure or borderline BP.

68. A patient with stable, regular narrow-complex SVT is actively wheezing from severe asthma, and vagal maneuvers failed. Which drug is the better choice?

    1. A. Diltiazem 0.25 mg/kg over 2 minutes
    2. B. Metoprolol 5 mg IV push
    3. C. Atropine 1 mg IV push
    4. D. Adenosine 12 mg as the first rapid IV push
    Show answer

    Answer: A. Diltiazem 0.25 mg/kg over 2 minutes

    Adenosine can provoke bronchospasm, so in active, severe asthma a nondihydropyridine calcium channel blocker such as diltiazem is a reasonable alternative for a stable patient with a good BP. Starting adenosine at 12 mg adds to that risk. Beta blockers can worsen bronchospasm. Atropine speeds AV conduction and does not treat SVT.

69. A stable patient has an irregularly irregular narrow-complex tachycardia at 150/min. Your partner reaches for adenosine. Why is this inappropriate?

    1. A. Adenosine must be dosed at 18 mg for this rhythm
    2. B. Adenosine reliably turns atrial fibrillation into VF
    3. C. Adenosine is too slow in onset for this rhythm
    4. D. Adenosine will not convert atrial fibrillation
    Show answer

    Answer: D. Adenosine will not convert atrial fibrillation

    Atrial fibrillation does not use an AV nodal reentry circuit, so adenosine only transiently slows the rate.

70. A patient in atrial fibrillation at 170/min has a BP of 70/40 and is confused. What is the most appropriate treatment?

    1. A. Diltiazem 0.25 mg/kg IV over 2 minutes
    2. B. Synchronized cardioversion
    3. C. Adenosine 6 mg rapid IV push
    4. D. Metoprolol 5 mg IV every 5 minutes
    Show answer

    Answer: B. Synchronized cardioversion

    Unstable tachycardia is treated with immediate synchronized cardioversion rather than rate-control drugs. Sedate if feasible.

71. A 12-kg toddler has SVT at 280/min with poor perfusion, and an IV is already in place. The pads are being applied. What is most appropriate?

    1. A. Amiodarone 60 mg rapid IV push
    2. B. Vagal maneuvers for 5 minutes first
    3. C. Diltiazem 3 mg over 2 minutes
    4. D. Adenosine 1.2 mg rapid IV push
    Show answer

    Answer: D. Adenosine 1.2 mg rapid IV push

    PALS treats SVT with poor perfusion with adenosine (0.1 mg/kg, here 1.2 mg) when IV/IO access is already available and it will not delay care, or with synchronized cardioversion. Calcium channel blockers can cause collapse in infants and young children. A rapid amiodarone push is the pulseless dose. Prolonged vagal attempts must not delay definitive treatment in a poorly perfused child.

72. A 3-year-old has a heart rate of 50/min from hypoxia during a respiratory illness and has poor perfusion. What is the first intervention?

    1. A. Give epinephrine 0.01 mg/kg IV/IO
    2. B. Give atropine 0.02 mg/kg IV/IO
    3. C. Begin transcutaneous pacing at once
    4. D. Oxygenate and ventilate with a bag-valve mask
    Show answer

    Answer: D. Oxygenate and ventilate with a bag-valve mask

    Pediatric bradycardia is most often due to hypoxia, so effective oxygenation and ventilation come before drugs.

73. An 82-year-old on digoxin has nausea, yellow-tinged vision, and a junctional bradycardia at 40/min. Which specific therapy may be needed in the hospital?

    1. A. Procainamide infusion at 20 mg/min
    2. B. Adenosine to reset the AV node
    3. C. Digoxin-specific antibody fragments (Fab)
    4. D. Additional digoxin to stabilize the rhythm
    Show answer

    Answer: C. Digoxin-specific antibody fragments (Fab)

    Digoxin immune Fab binds digoxin and is the specific treatment for life-threatening digoxin toxicity.

74. A stable patient has a regular, monomorphic wide-complex tachycardia at 180/min. Per ACLS guidance, adenosine:

    1. A. Is contraindicated in every wide-complex rhythm
    2. B. Is the drug of choice for polymorphic VT
    3. C. May be considered for diagnosis and treatment
    4. D. Should be given as 12 mg by slow IV push
    Show answer

    Answer: C. May be considered for diagnosis and treatment

    Adenosine may be considered only when a wide-complex tachycardia is regular and monomorphic; it is avoided in irregular or polymorphic rhythms.

75. A patient with stable SVT also has severe, actively wheezing asthma. What is the main concern with giving adenosine?

    1. A. It can provoke bronchospasm
    2. B. It causes sustained hypertension
    3. C. It worsens albuterol's tachycardia
    4. D. It causes severe hypokalemia
    Show answer

    Answer: A. It can provoke bronchospasm

    Adenosine can cause bronchoconstriction, so caution is warranted in patients with reactive airway disease. Its effects last seconds, so it does not add lasting tachycardia, and it does not lower potassium.

76. Adenosine 6 mg was pushed slowly through a hand IV without a flush, and nothing happened. What is the most likely reason?

    1. A. The rhythm must be ventricular tachycardia
    2. B. The 6 mg dose was too large to be effective
    3. C. The patient has genetic resistance to adenosine
    4. D. The drug was metabolized before reaching the heart
    Show answer

    Answer: D. The drug was metabolized before reaching the heart

    Adenosine's half-life is under 10 seconds, so it must be pushed rapidly through a proximal vein followed immediately by a flush.

77. A conscious patient being transcutaneously paced at 70 mA reports severe pain, and the BP has improved. What is appropriate?

    1. A. Withhold medication to protect the BP
    2. B. Turn the pacer off and give atropine
    3. C. Give analgesia or sedation per protocol
    4. D. Lower the paced rate to 40/min to ease pain
    Show answer

    Answer: C. Give analgesia or sedation per protocol

    Pacing is painful; small titrated doses of an analgesic such as fentanyl or a sedative such as midazolam are commonly used. Dropping the paced rate below what the patient needs gives up the perfusion that pacing restored.

78. During a lidocaine infusion, an elderly patient develops slurred speech, tinnitus, and muscle twitching. What is the most appropriate action?

    1. A. Give atropine to counter the vagal effects
    2. B. Stop the infusion and suspect lidocaine toxicity
    3. C. Give a 1.5 mg/kg bolus to stabilize the patient
    4. D. Increase the rate because levels are subtherapeutic
    Show answer

    Answer: B. Stop the infusion and suspect lidocaine toxicity

    CNS signs such as paresthesias, tinnitus, slurred speech, and twitching precede lidocaine-induced seizures; elderly patients are at higher risk.

79. A 24-year-old has sinus tachycardia at 140/min, agitation, diaphoresis, and a BP of 168/98 after using cocaine. What is the first-line drug?

    1. A. Synchronized cardioversion at 50 J
    2. B. Amiodarone 150 mg over 10 minutes
    3. C. A benzodiazepine such as midazolam
    4. D. Adenosine 6 mg rapid IV push
    Show answer

    Answer: C. A benzodiazepine such as midazolam

    Cocaine-induced sinus tachycardia and hypertension come from sympathetic stimulation, and benzodiazepines reduce that drive and the agitation. Adenosine only slows sinus tachycardia for seconds. Cardioversion cannot convert sinus rhythm. Amiodarone does not treat sympathomimetic toxicity.