front 1 A cardiac pacemaker current opens when the membrane becomes more negative near the end of repolarization. Which channel behavior best describes the If current? A. Outward K+ channel opens | back 1 B. Inward Na+ channel opens |
front 2 Increased extracellular potassium most commonly causes which effect on pacemaker cells? A. Speeds automatic firing | back 2 B. Stops or slows firing |
front 3 A hospitalized patient on aggressive diuresis develops palpitations and frequent premature beats. Which electrolyte change most facilitates ectopic pacemakers? A. Hypermagnesemia | back 3 C. Hypokalemia |
front 4 Which electrophysiologic profile is most consistent with hyperkalemia? A. Longer AP, faster conduction | back 4 C. Shorter AP, slower conduction |
front 5 Which pattern is most characteristic of hypokalemia in cardiac tissue? A. Prolonged AP, more arrhythmias | back 5 A. Prolonged AP, more arrhythmias |
front 6 A patient receives a β-blocker for sinus tachycardia. Which part of the pacemaker action potential is primarily reduced? A. Phase 0 upstroke | back 6 D. Phase 4 slope |
front 7 Increased vagal discharge slows SA-node firing not only by flattening phase 4, but also by: A. Shortening atrial refractory period | back 7 B. Making diastolic potential more negative |
front 8 Which change most directly accelerates pacemaker discharge? A. Decreased phase 4 slope | back 8 B. Increased phase 4 slope |
front 9 Which condition would be expected to accelerate pacemaker discharge by steepening phase 4? A. β-adrenergic stimulation | back 9 A. β-adrenergic stimulation |
front 10 A patient with congenital long-QT syndrome has a pause-dependent polymorphic ventricular arrhythmia. Which triggered activity is most likely? A. DAD during phase 4 | back 10 B. EAD during phase 3 |
front 11 Early afterdepolarizations are classically worsened by which rhythm condition? A. Fast heart rates | back 11 C. Slow heart rates |
front 12 A patient with digitalis excess develops triggered ventricular beats that worsen with tachycardia. Which mechanism best explains this arrhythmia? A. EAD in phase 3 | back 12 B. DAD in phase 4 |
front 13 Delayed afterdepolarizations are most strongly linked to which intracellular abnormality? A. Reduced intracellular sodium | back 13 B. Increased intracellular calcium |
front 14 A patient with myocardial ischemia develops tachy-triggered ectopy consistent with delayed afterdepolarizations. Which additional setting is classically associated with the same mechanism? A. Long-QT bradycardia | back 14 B. Catecholamine excess |
front 15 A patient with partial AV block due to excessive parasympathetic tone improves after a muscarinic antagonist. Which drug was most likely given? A. Adenosine | back 15 B. Atropine |
front 16 An electrophysiologist describes an arrhythmia in which a single impulse repeatedly reenters previously activated myocardium. What is this mechanism also called? A. Triggered activity | back 16 B. Circus movement |
front 17 A young adult has paroxysmal tachycardia due to an accessory AV pathway connecting atria and ventricles outside the AV node. Which syndrome is most likely? A. Lown-Ganong-Levine | back 17 C. Wolff-Parkinson-White |
front 18 In Wolff-Parkinson-White syndrome, the accessory bypass tract is called the: A. Bundle of His | back 18 B. Bundle of Kent |
front 19 For a reentry circuit to sustain itself, the conduction time around the loop must be: A. Shorter than the ERP | back 19 C. Longer than the ERP |
front 20 Why does reentry fail when conduction time around a circuit is too short? A. Tissue remains superexcitable | back 20 B. Tissue is still refractory |
front 21 A patient has a macroreentrant tachycardia. One antiarrhythmic strategy is to make the returning impulse encounter tissue that still cannot be re-excited. This is best accomplished by: A. Shortening refractory period | back 21 B. Increasing refractory period |
front 22 In a patient with a reentry-mediated arrhythmia, a drug abolishes the circuit by delaying impulse travel until previously activated tissue becomes unexcitable. Which effect best explains this? A. Further slowing conduction | back 22 A. Further slowing conduction |
front 23 Antiarrhythmic drugs generally suppress the automaticity of which pacemaker source more than the SA node? A. AV nodal tissue | back 23 C. Ectopic pacemakers |
front 24 Antiarrhythmic drugs typically alter conduction, excitability, and refractoriness more strongly in which tissue? A. Normally polarized tissue | back 24 B. Depolarized tissue |
front 25 A sodium-channel blocker is most effective during rapid tachycardia because it preferentially binds channels in which states? A. Resting and closed | back 25 B. Activated and inactivated |
front 26 Useful channel-blocking antiarrhythmics bind poorly or not at all to which channel state? A. Activated | back 26 C. Resting |
front 27 A ventricular tachyarrhythmia slows after administration of a drug whose effect becomes stronger the more often channels cycle through opening and inactivation. This property is called: A. Reverse dependence | back 27 B. State dependence |
front 28 A drug blocks diseased myocardium particularly well when the resting potential is lost and many channels remain unavailable even at rest. Which state predominates in that tissue? A. Resting channels | back 28 C. Inactivated channels |
front 29 In cells with abnormal automaticity, antiarrhythmic drugs most commonly reduce spontaneous firing by reducing the slope of which phase? A. Phase 0 | back 29 D. Phase 4 |
front 30 In abnormal automatic foci, reduction of phase-4 slope is most often achieved by blocking which ions’ channels? A. K+ or Cl− | back 30 B. Na+ or Ca2+ |
front 31 As antiarrhythmics flatten phase 4 in abnormal automatic cells, the resting membrane potential tends to move closer to the equilibrium potential of: A. Sodium | back 31 C. Potassium |
front 32 Which Vaughan-Williams class acts primarily by sodium-channel blockade? A. Class I | back 32 A. Class I |
front 33 A patient with atrial arrhythmia receives a Class IA drug. What is the expected effect on action-potential duration? A. Minimal change | back 33 C. Prolongation |
front 34 Which channel-binding kinetic profile is characteristic of Class IA antiarrhythmics? A. Rapid dissociation | back 34 B. Intermediate dissociation |
front 35 A Class IB antiarrhythmic is chosen for ventricular ectopy. Which combination best describes it? A. Prolongs AP; slow kinetics | back 35 B. Shortens AP; rapid kinetics |
front 36 A Class IC agent is started for a supraventricular arrhythmia. Which property best fits this drug subclass? A. Shortens AP markedly | back 36 C. Minimal AP effect |
front 37 Compared with Class IA and IB drugs, Class IC drugs dissociate from sodium channels with: A. Very rapid kinetics | back 37 C. Slow kinetics |
front 38 A patient’s antiarrhythmic decreases sympathetic influence on the heart rather than primarily blocking sodium channels. Which class is this? A. Class I | back 38 B. Class II |
front 39 The principal cardiac target reduced by Class II antiarrhythmic drugs is: A. Muscarinic activity | back 39 B. Beta-adrenergic activity |
front 40 A patient with recurrent ventricular tachycardia is started on a Class III antiarrhythmic. What is the core electrophysiologic action of this class? A. Blocks fast Na+ channels | back 40 B. Prolongs action potential duration |
front 41 A drug is classified as Class III because it blocks which current? A. IK1 inward rectifier K+ | back 41 D. Rapid delayed rectifier K+ |
front 42 A supraventricular tachycardia is treated with a Class IV agent. What is the primary mechanism? A. Beta-receptor antagonism | back 42 C. Cardiac Ca2+ current blockade |
front 43 A drug slows conduction most strongly in tissues whose phase 0 upstroke depends on calcium entry. Which structures are most affected? A. Atria and ventricles | back 43 C. AV node and SA node Calcium-dependent upstroke tissues include the AV and SA nodes. |
front 44 Which antiarrhythmic displays properties spanning all four Vaughan-Williams classes? A. Procainamide | back 44 B. Amiodarone |
front 45 A patient becomes hypotensive shortly after receiving procainamide. This is partly due to which additional pharmacologic property? A. Ganglion blockade | back 45 A. Ganglion blockade |
front 46 Procainamide lowers peripheral vascular resistance primarily by causing: A. Increased vagal outflow | back 46 D. Decreased sympathetic ganglionic tone |
front 47 A Class IA antiarrhythmic slows the phase-0 upstroke in ventricular myocardium. Which ECG change is most expected with procainamide? A. Shortened QT interval | back 47 C. Prolonged QRS duration |
front 48 Procainamide decreases conduction mainly through blockade of: A. Na+ channels | back 48 A. Na+ channels |
front 49 Procainamide prolongs action potential duration primarily because it also blocks: A. Chloride channels | back 49 B. K+ channels |
front 50 N-acetylprocainamide is best classified as which antiarrhythmic subclass? A. Class IA | back 50 D. Class III |
front 51 A patient with renal failure on procainamide develops polymorphic ventricular tachycardia. Accumulation of which metabolite is the likely culprit? A. Norquinidine | back 51 D. N-acetylprocainamide |
front 52 The ventricular arrhythmia most classically linked to excess NAPA is: A. Monomorphic VT | back 52 B. Torsades de pointes |
front 53 Quinidine most closely resembles which drug in its electrophysiologic actions? A. Lidocaine | back 53 C. Procainamide |
front 54 Which antiarrhythmic has effects very similar to procainamide and quinidine? A. Disopyramide | back 54 A. Disopyramide |
front 55 A patient with atrial flutter is given disopyramide. To avoid dangerous ventricular responses, what should also be added? A. A drug slowing AV conduction | back 55 A. A drug slowing AV conduction With atrial flutter/fibrillation, AV nodal slowing should also be provided. |
front 56 Disopyramide is most likely to worsen which comorbidity because of its negative cardiac effect? A. Hypertension | back 56 C. Heart failure |
front 57 Dry mouth, urinary retention, constipation, blurred vision, and glaucoma worsening during disopyramide therapy are best explained by: A. Histamine blockade | back 57 B. Atropine-like activity |
front 58 In the United States, disopyramide is approved only for treatment of: A. Atrial fibrillation | back 58 C. Ventricular arrhythmias |
front 59 Lidocaine is most accurately described as blocking which channels with rapid kinetics? A. K+ channels | back 59 B. Na+ channels |
front 60 Lidocaine preferentially affects which cardiac tissues? A. SA nodal and atrial | back 60 C. Ventricular and Purkinje |
front 61 An older patient on lidocaine develops paresthesias, tremor, slurred speech, and lightheadedness. These adverse effects are best categorized as: A. Neurologic | back 61 A. Neurologic |
front 62 After successful cardioversion, which drug is the agent of choice to help prevent recurrent ventricular fibrillation? A. Procainamide | back 62 B. Lidocaine |
front 63 A man taking mexiletine reports tremor, lethargy, blurred vision, and intermittent nausea. Which adverse-effect category best fits this drug? A. Neurologic | back 63 A. Neurologic |
front 64 Flecainide most directly blocks which channels? A. Ca2+ only | back 64 C. Na+ and K+ |
front 65 Which kinetic property best characterizes flecainide channel unblocking? A. Rapid kinetics | back 65 B. Slow kinetics |
front 66 Flecainide is most appropriately used in patients with: A. Healthy hearts, supraventricular arrhythmias | back 66 A. Healthy hearts, supraventricular arrhythmias |
front 67 Which electrophysiologic effect is expected with flecainide? A. QT prolongation | back 67 D. No QT prolongation |
front 68 A patient with prior myocardial infarction and preexisting ventricular ectopy is given flecainide. What is the major concern? A. Severe bradycardia only | back 68 C. Arrhythmia exacerbation |
front 69 In addition to its approved main use, flecainide is noted to be very effective at suppressing: A. Atrial standstill | back 69 B. Premature ventricular contractions |
front 70 Propafenone is used primarily for which group of arrhythmias? A. Ventricular arrhythmias | back 70 D. Supraventricular arrhythmias |
front 71 Which additional property does propafenone possess? A. Weak beta blockade | back 71 A. Weak beta blockade |
front 72 Which statement about propafenone is correct? A. Markedly prolongs QT | back 72 C. Does not prolong AP |
front 73 A class III antiarrhythmic prolongs repolarization more at slow heart rates than at fast heart rates. This phenomenon is called: A. State dependence | back 73 B. Reverse-use dependence |
front 74 Reverse-use dependence with most class III agents is clinically dangerous because it can promote: A. Torsades de pointes | back 74 A. Torsades de pointes |
front 75 Most class III antiarrhythmic drugs characteristically prolong the: A. PR interval | back 75 D. QT interval |
front 76 Which drug is an amiodarone analogue lacking iodine and used for atrial flutter or atrial fibrillation? A. Sotalol | back 76 C. Dronedarone |
front 77 Which class III drug does not show reverse-use dependence and instead prolongs action potentials relatively uniformly across heart rates? A. Dronedarone | back 77 B. Amiodarone |
front 78 Shortly after IV antiarrhythmic therapy, a patient develops notable peripheral vasodilation. Which drug most likely caused this? A. Flecainide | back 78 D. Amiodarone |
front 79 Amiodarone is primarily metabolized by which CYP enzyme? A. CYP2D6 | back 79 B. CYP3A4 |
front 80 A patient taking amiodarone starts cimetidine. What is the expected effect on amiodarone levels? A. Levels decrease | back 80 C. Levels increase |
front 81 A patient on amiodarone begins rifampin. What is the expected pharmacokinetic effect? A. Levels increase | back 81 D. Levels decrease |
front 82 Dronedarone acts on calcium, sodium, and potassium channels and also has what additional action? A. Alpha blockade | back 82 B. Beta blockade |
front 83 Dronedarone should not be coadministered with which drug group? A. Thiazides | back 83 D. Azoles |
front 84 A wide-complex ventricular tachycardia is misdiagnosed as supraventricular tachycardia in the emergency department. Which IV drug is the classic dangerous error? A. Lidocaine | back 84 C. Verapamil |
front 85 Giving IV verapamil to true ventricular tachycardia can precipitate: A. Hyperkalemia | back 85 B. Ventricular fibrillation |
front 86 Which extracardiac adverse effect is classically associated with verapamil? A. Constipation | back 86 A. Constipation |
front 87 Which arrhythmia is the major indication for verapamil? A. Ventricular tachycardia | back 87 B. Supraventricular tachycardia |
front 88 A hemodynamically stable young adult has paroxysmal SVT and needs rapid conversion to sinus rhythm in the emergency department. Which drug is preferred? A. Verapamil | back 88 D. Adenosine |
front 89 In normal ventricular myocytes, ranolazine has what net electrophysiologic effect? A. Prolonged AP and QT | back 89 A. Prolonged AP and QT |
front 90 Which Vaughan-Williams class corresponds to sodium-channel blockade? A. Class II | back 90 C. Class I |
front 91 Which Vaughan-Williams class is primarily sympatholytic through β-blockade? A. Class I | back 91 B. Class II |
front 92 Which Vaughan-Williams class works mainly by prolonging repolarization through potassium-channel blockade? A. Class III | back 92 A. Class III |
front 93 Which Vaughan-Williams class is composed of calcium-channel blockers? A. Class II | back 93 D. Class IV |
front 94 Procainamide belongs to which antiarrhythmic subclass? A. Class IB | back 94 C. Class IA |
front 95 A patient started on procainamide develops widening of ventricular depolarization and delayed repolarization. What ECG changes are expected? A. Prolonged QRS and QT | back 95 A. Prolonged QRS and QT |
front 96 Besides Class IA activity, procainamide also has actions resembling which class? A. Class IV | back 96 D. Class III |
front 97 Long-term procainamide therapy can produce a syndrome resembling which disease? A. Rheumatoid arthritis | back 97 C. Lupus |
front 98 Quinidine belongs to which antiarrhythmic subclass? A. Class IB | back 98 D. Class IA |
front 99 Toxic quinidine levels most classically prolong which ECG interval? A. QT | back 99 A. QT |
front 100 A patient on quinidine reports headache, dizziness, and tinnitus. This triad most strongly suggests: A. Digitalis effect | back 100 C. Cinchonism |
front 101 Which organ system is especially prone to adverse effects from quinidine? A. Renal | back 101 B. GI |
front 102 Compared with other Class IA agents, disopyramide is particularly notable for which additional effect? A. Strong β blockade | back 102 C. Pronounced antimuscarinic effects |
front 103 Disopyramide adverse effect? A. Fecal incontinence | back 103 B. Urinary retention |
front 104 Lidocaine belongs to which antiarrhythmic subclass? A. Class IA | back 104 D. Class IB |
front 105 Because of extensive first-pass metabolism, lidocaine used as an antiarrhythmic is typically given: A. Intravenously | back 105 A. Intravenously |
front 106 A patient with digoxin toxicity develops ventricular ectopy. Which antiarrhythmic from your material is also used for digitalis-induced arrhythmias? A. Lidocaine | back 106 A. Lidocaine |
front 107 Mexiletine belongs to which Vaughan-Williams subclass? A. Class IA | back 107 C. Class IB |
front 108 Flecainide belongs to which antiarrhythmic subclass? A. Class IA | back 108 D. Class IC |
front 109 Propafenone belongs to which antiarrhythmic subclass? A. Class IV | back 109 B. Class IC |
front 110 Which additional pharmacologic property does propafenone possess? A. Alpha-blocking activity | back 110 C. Beta-blocking activity |
front 111 Which short-acting β-blocker is specifically used as an antiarrhythmic? A. Propranolol | back 111 D. Esmolol |
front 112 Which β-blocker also has partial Class III antiarrhythmic activity? A. Nebivolol | back 112 B. Sotalol |
front 113 Sotalol predisposes patients to which arrhythmia? A. Sinus arrest | back 113 C. Torsades de pointes |
front 114 Amiodarone is classified primarily as which antiarrhythmic class? A. Class III | back 114 A. Class III |
front 115 Which channel/current is classically blocked by amiodarone? A. If current | back 115 B. IKr |
front 116 Amiodarone interferes with metabolism of which hormone pathway? A. T3 to T4 | back 116 C. T4 to T3 |
front 117 A patient on amiodarone also takes warfarin, digoxin, and a statin. Why is close monitoring needed? A. Amiodarone induces CYP3A4 | back 117 C. Amiodarone inhibits P450 enzymes |
front 118 Which Class III drug resembles amiodarone structurally but lacks its effect on thyroid hormone metabolism? A. Ibutilide | back 118 B. Dronedarone |
front 119 Which major toxicity is especially emphasized for dronedarone? A. Nephrotoxicity | back 119 C. Hepatotoxicity |
front 120 Dofetilide and ibutilide specifically block which current? A. INa | back 120 D. IKr |
front 121 Verapamil and diltiazem belong to which antiarrhythmic class? A. Class III | back 121 C. Class IV |
front 122 A patient overdoses on verapamil. Which toxic effect is most expected? A. AV block, severe depression | back 122 A. AV block, severe depression |
front 123 Which nucleoside is both a prominent vasodilator and an antiarrhythmic, and is the drug of choice for SVT? A. Adenosine | back 123 A. Adenosine |
front 124 What is the mechanism of action of ivabradine? A. Blocks AV nodal calcium current | back 124 C. Blocks If in SA node |
front 125 A patient with digitalis-induced arrhythmias needs adjunctive ion therapy. Which is preferred? A. Calcium | back 125 D. Magnesium |
front 126 Which antiarrhythmic from your list can be used to treat Wolff-Parkinson-White syndrome? A. Verapamil | back 126 B. Procainamide |