Pharm 14 Flashcards

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
B. Inward Na+ channel opens
C. Inward Ca2+ channel closes
D. Outward Cl− channel opens

Increased extracellular potassium most commonly causes which effect on pacemaker cells?

A. Speeds automatic firing
B. Stops or slows firing
C. Increases triggered activity
D. Prolongs refractory recovery

A hospitalized patient on aggressive diuresis develops palpitations and frequent premature beats. Which electrolyte change most facilitates ectopic pacemakers?

A. Hypermagnesemia
B. Hypercalcemia
C. Hypokalemia
D. Hyponatremia

Which electrophysiologic profile is most consistent with hyperkalemia?

A. Longer AP, faster conduction
B. Longer AP, faster pacemaker
C. Shorter AP, slower conduction
D. Shorter AP, faster pacemaker

Which pattern is most characteristic of hypokalemia in cardiac tissue?

A. Prolonged AP, more arrhythmias
B. Shortened AP, less automaticity
C. Slower rate, less ectopy
D. Faster conduction, shorter ERP

A patient receives a β-blocker for sinus tachycardia. Which part of the pacemaker action potential is primarily reduced?

A. Phase 0 upstroke
B. Phase 1 notch
C. Phase 3 repolarization
D. Phase 4 slope

Increased vagal discharge slows SA-node firing not only by flattening phase 4, but also by:

A. Shortening atrial refractory period
B. Making diastolic potential more negative
C. Increasing phase 0 amplitude
D. Blocking ventricular calcium channels

Which change most directly accelerates pacemaker discharge?

A. Decreased phase 4 slope
B. Increased phase 4 slope
C. Shortened phase 0
D. Prolonged plateau duration

Which condition would be expected to accelerate pacemaker discharge by steepening phase 4?

A. β-adrenergic stimulation
B. Vagal stimulation
C. Severe hyperkalemia
D. Class II blockade

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
B. EAD during phase 3
C. Reentry during phase 0
D. Automaticity during phase 1

Early afterdepolarizations are classically worsened by which rhythm condition?

A. Fast heart rates
B. Irregular AV block
C. Slow heart rates
D. Ventricular pacing

A patient with digitalis excess develops triggered ventricular beats that worsen with tachycardia. Which mechanism best explains this arrhythmia?

A. EAD in phase 3
B. DAD in phase 4
C. Reentry in AV node
D. Block in bundle branch

Delayed afterdepolarizations are most strongly linked to which intracellular abnormality?

A. Reduced intracellular sodium
B. Increased intracellular calcium
C. Reduced intracellular potassium
D. Increased intracellular chloride

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
B. Catecholamine excess
C. Complete AV block
D. Severe hypothermia

A patient with partial AV block due to excessive parasympathetic tone improves after a muscarinic antagonist. Which drug was most likely given?

A. Adenosine
B. Atropine
C. Verapamil
D. Propranolol

An electrophysiologist describes an arrhythmia in which a single impulse repeatedly reenters previously activated myocardium. What is this mechanism also called?

A. Triggered activity
B. Circus movement
C. Phase-4 automaticity
D. Exit block

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
B. Mobitz type I
C. Wolff-Parkinson-White
D. Brugada syndrome

In Wolff-Parkinson-White syndrome, the accessory bypass tract is called the:

A. Bundle of His
B. Bundle of Kent
C. Bachmann bundle
D. Moderator band

For a reentry circuit to sustain itself, the conduction time around the loop must be:

A. Shorter than the ERP
B. Equal to the ERP
C. Longer than the ERP
D. Independent of the ERP

Why does reentry fail when conduction time around a circuit is too short?

A. Tissue remains superexcitable
B. Tissue is still refractory
C. Calcium stores are depleted
D. Sodium channels are upregulated

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
B. Increasing refractory period
C. Increasing phase 4 slope
D. Accelerating AV conduction

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
B. Faster sinus discharge
C. Shorter action potential
D. Enhanced ectopic automaticity

Antiarrhythmic drugs generally suppress the automaticity of which pacemaker source more than the SA node?

A. AV nodal tissue
B. Purkinje reserve rhythm
C. Ectopic pacemakers
D. Atrial myocardium

Antiarrhythmic drugs typically alter conduction, excitability, and refractoriness more strongly in which tissue?

A. Normally polarized tissue
B. Depolarized tissue
C. Fibrotic valves
D. Pericardial tissue

A sodium-channel blocker is most effective during rapid tachycardia because it preferentially binds channels in which states?

A. Resting and closed
B. Activated and inactivated
C. Resting and refractory
D. Closed and repolarized

Useful channel-blocking antiarrhythmics bind poorly or not at all to which channel state?

A. Activated
B. Inactivated
C. Resting
D. Open-refractory

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
B. State dependence
C. Chemical antagonism
D. Noncompetitive blockade

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
B. Closed channels
C. Inactivated channels
D. Dephosphorylated channels

In cells with abnormal automaticity, antiarrhythmic drugs most commonly reduce spontaneous firing by reducing the slope of which phase?

A. Phase 0
B. Phase 2
C. Phase 3
D. Phase 4

In abnormal automatic foci, reduction of phase-4 slope is most often achieved by blocking which ions’ channels?

A. K+ or Cl−
B. Na+ or Ca2+
C. Mg2+ or K+
D. Cl− or Ca2+

As antiarrhythmics flatten phase 4 in abnormal automatic cells, the resting membrane potential tends to move closer to the equilibrium potential of:

A. Sodium
B. Calcium
C. Potassium
D. Chloride

Which Vaughan-Williams class acts primarily by sodium-channel blockade?

A. Class I
B. Class II
C. Class III
D. Class IV

A patient with atrial arrhythmia receives a Class IA drug. What is the expected effect on action-potential duration?

A. Minimal change
B. Shortening
C. Prolongation
D. Biphasic effect

Which channel-binding kinetic profile is characteristic of Class IA antiarrhythmics?

A. Rapid dissociation
B. Intermediate dissociation
C. Slow dissociation
D. No measurable dissociation

A Class IB antiarrhythmic is chosen for ventricular ectopy. Which combination best describes it?

A. Prolongs AP; slow kinetics
B. Shortens AP; rapid kinetics
C. Minimal AP effect; slow kinetics
D. Prolongs AP; intermediate kinetics

A Class IC agent is started for a supraventricular arrhythmia. Which property best fits this drug subclass?

A. Shortens AP markedly
B. Prolongs AP markedly
C. Minimal AP effect
D. β-receptor blockade

Compared with Class IA and IB drugs, Class IC drugs dissociate from sodium channels with:

A. Very rapid kinetics
B. Intermediate kinetics
C. Slow kinetics
D. Zero-order kinetics

A patient’s antiarrhythmic decreases sympathetic influence on the heart rather than primarily blocking sodium channels. Which class is this?

A. Class I
B. Class II
C. Class III
D. Class IV

The principal cardiac target reduced by Class II antiarrhythmic drugs is:

A. Muscarinic activity
B. Beta-adrenergic activity
C. Sodium-potassium ATPase
D. Funny-channel current

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
B. Prolongs action potential duration
C. Blocks cardiac Ca2+ current
D. Reduces beta-adrenergic activity

A drug is classified as Class III because it blocks which current?

A. IK1 inward rectifier K+
B. Funny Na+ current
C. L-type skeletal Ca2+ current
D. Rapid delayed rectifier K+

A supraventricular tachycardia is treated with a Class IV agent. What is the primary mechanism?

A. Beta-receptor antagonism
B. Na/K ATPase inhibition
C. Cardiac Ca2+ current blockade
D. Delayed rectifier K+ blockade

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
B. His bundle and Purkinje
C. AV node and SA node
D. Ventricles and papillary muscle

Which antiarrhythmic displays properties spanning all four Vaughan-Williams classes?

A. Procainamide
B. Amiodarone
C. Lidocaine
D. Disopyramide

A patient becomes hypotensive shortly after receiving procainamide. This is partly due to which additional pharmacologic property?

A. Ganglion blockade
B. Beta-2 antagonism
C. Muscarinic agonism
D. Direct nitric oxide release

Procainamide lowers peripheral vascular resistance primarily by causing:

A. Increased vagal outflow
B. Coronary vasospasm
C. Renal vasoconstriction
D. Decreased sympathetic ganglionic tone

A Class IA antiarrhythmic slows the phase-0 upstroke in ventricular myocardium. Which ECG change is most expected with procainamide?

A. Shortened QT interval
B. Narrowed QRS complex
C. Prolonged QRS duration
D. Shortened PR interval

Procainamide decreases conduction mainly through blockade of:

A. Na+ channels
B. Ca2+ channels
C. If channels
D. KATP channels

Procainamide prolongs action potential duration primarily because it also blocks:

A. Chloride channels
B. K+ channels
C. Funny channels
D. T-type Ca2+ channels

N-acetylprocainamide is best classified as which antiarrhythmic subclass?

A. Class IA
B. Class IB
C. Class IC
D. Class III

A patient with renal failure on procainamide develops polymorphic ventricular tachycardia. Accumulation of which metabolite is the likely culprit?

A. Norquinidine
B. Monoethylglycinexylidide
C. Desethylamiodarone
D. N-acetylprocainamide

The ventricular arrhythmia most classically linked to excess NAPA is:

A. Monomorphic VT
B. Torsades de pointes
C. Ventricular flutter
D. Accelerated idioventricular rhythm

Quinidine most closely resembles which drug in its electrophysiologic actions?

A. Lidocaine
B. Verapamil
C. Procainamide
D. Amiodarone

Which antiarrhythmic has effects very similar to procainamide and quinidine?

A. Disopyramide
B. Lidocaine
C. Sotalol
D. Diltiazem

A patient with atrial flutter is given disopyramide. To avoid dangerous ventricular responses, what should also be added?

A. A drug slowing AV conduction
B. A potassium supplement
C. A direct vasodilator
D. A class IB agent

Disopyramide is most likely to worsen which comorbidity because of its negative cardiac effect?

A. Hypertension
B. Stable angina
C. Heart failure
D. Mitral stenosis

Dry mouth, urinary retention, constipation, blurred vision, and glaucoma worsening during disopyramide therapy are best explained by:

A. Histamine blockade
B. Atropine-like activity
C. Alpha-1 agonism
D. Nicotinic stimulation

In the United States, disopyramide is approved only for treatment of:

A. Atrial fibrillation
B. AV nodal reentry
C. Ventricular arrhythmias
D. Sinus tachycardia

Lidocaine is most accurately described as blocking which channels with rapid kinetics?

A. K+ channels
B. Na+ channels
C. Ca2+ channels
D. If channels

Lidocaine preferentially affects which cardiac tissues?

A. SA nodal and atrial
B. Atrial and AV nodal
C. Ventricular and Purkinje
D. AV nodal and His

An older patient on lidocaine develops paresthesias, tremor, slurred speech, and lightheadedness. These adverse effects are best categorized as:

A. Neurologic
B. Renal
C. Endocrine
D. Hematologic

After successful cardioversion, which drug is the agent of choice to help prevent recurrent ventricular fibrillation?

A. Procainamide
B. Lidocaine
C. Verapamil
D. Dronedarone

A man taking mexiletine reports tremor, lethargy, blurred vision, and intermittent nausea. Which adverse-effect category best fits this drug?

A. Neurologic
B. Hepatic
C. Endocrine
D. Hematologic

Flecainide most directly blocks which channels?

A. Ca2+ only
B. K+ only
C. Na+ and K+
D. Na+ and Ca2+

Which kinetic property best characterizes flecainide channel unblocking?

A. Rapid kinetics
B. Slow kinetics
C. Intermediate kinetics
D. Biphasic kinetics

Flecainide is most appropriately used in patients with:

A. Healthy hearts, supraventricular arrhythmias
B. Prior MI, ventricular ectopy
C. Damaged hearts, ventricular tachycardia
D. Heart failure, atrial flutter

Which electrophysiologic effect is expected with flecainide?

A. QT prolongation
B. AP prolongation
C. Marked ERP shortening
D. No QT prolongation

A patient with prior myocardial infarction and preexisting ventricular ectopy is given flecainide. What is the major concern?

A. Severe bradycardia only
B. Coronary vasospasm
C. Arrhythmia exacerbation
D. AV block reversal

In addition to its approved main use, flecainide is noted to be very effective at suppressing:

A. Atrial standstill
B. Premature ventricular contractions
C. Torsades de pointes
D. Junctional escape beats

Propafenone is used primarily for which group of arrhythmias?

A. Ventricular arrhythmias
B. Digitalis arrhythmias
C. Ischemic automaticity
D. Supraventricular arrhythmias

Which additional property does propafenone possess?

A. Weak beta blockade
B. Strong alpha blockade
C. Muscarinic agonism
D. Nitrate-like dilation

Which statement about propafenone is correct?

A. Markedly prolongs QT
B. Greatly prolongs AP
C. Does not prolong AP
D. Shortens SA recovery

A class III antiarrhythmic prolongs repolarization more at slow heart rates than at fast heart rates. This phenomenon is called:

A. State dependence
B. Reverse-use dependence
C. Tachyphylaxis
D. Phase trapping

Reverse-use dependence with most class III agents is clinically dangerous because it can promote:

A. Torsades de pointes
B. Ventricular standstill
C. Sinus arrest only
D. WPW conduction block

Most class III antiarrhythmic drugs characteristically prolong the:

A. PR interval
B. QRS interval
C. ST segment
D. QT interval

Which drug is an amiodarone analogue lacking iodine and used for atrial flutter or atrial fibrillation?

A. Sotalol
B. Procainamide
C. Dronedarone
D. Mexiletine

Which class III drug does not show reverse-use dependence and instead prolongs action potentials relatively uniformly across heart rates?

A. Dronedarone
B. Amiodarone
C. Sotalol
D. Quinidine

Shortly after IV antiarrhythmic therapy, a patient develops notable peripheral vasodilation. Which drug most likely caused this?

A. Flecainide
B. Propafenone
C. Verapamil
D. Amiodarone

Amiodarone is primarily metabolized by which CYP enzyme?

A. CYP2D6
B. CYP3A4
C. CYP2C19
D. CYP1A2

A patient taking amiodarone starts cimetidine. What is the expected effect on amiodarone levels?

A. Levels decrease
B. No change
C. Levels increase
D. Clearance doubles

A patient on amiodarone begins rifampin. What is the expected pharmacokinetic effect?

A. Levels increase
B. Protein binding rises
C. Half-life doubles
D. Levels decrease

Dronedarone acts on calcium, sodium, and potassium channels and also has what additional action?

A. Alpha blockade
B. Beta blockade
C. Muscarinic blockade
D. Adenosine agonism

Dronedarone should not be coadministered with which drug group?

A. Thiazides
B. Statins
C. Sulfonylureas
D. Azoles

A wide-complex ventricular tachycardia is misdiagnosed as supraventricular tachycardia in the emergency department. Which IV drug is the classic dangerous error?

A. Lidocaine
B. Procainamide
C. Verapamil
D. Mexiletine

Giving IV verapamil to true ventricular tachycardia can precipitate:

A. Hyperkalemia
B. Ventricular fibrillation
C. Atrial standstill
D. Sinus tachycardia

Which extracardiac adverse effect is classically associated with verapamil?

A. Constipation
B. Hemolysis
C. Bronchospasm
D. Tinnitus

Which arrhythmia is the major indication for verapamil?

A. Ventricular tachycardia
B. Supraventricular tachycardia
C. Ventricular fibrillation
D. Torsades de pointes

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
B. Lidocaine
C. Procainamide
D. Adenosine

In normal ventricular myocytes, ranolazine has what net electrophysiologic effect?

A. Prolonged AP and QT
B. Shortened AP and QT
C. Prolonged PR only
D. Shortened QRS only

Which Vaughan-Williams class corresponds to sodium-channel blockade?

A. Class II
B. Class III
C. Class I
D. Class IV

Which Vaughan-Williams class is primarily sympatholytic through β-blockade?

A. Class I
B. Class II
C. Class III
D. Class IV

Which Vaughan-Williams class works mainly by prolonging repolarization through potassium-channel blockade?

A. Class III
B. Class I
C. Class IV
D. Class II

Which Vaughan-Williams class is composed of calcium-channel blockers?

A. Class II
B. Class III
C. Class I
D. Class IV

Procainamide belongs to which antiarrhythmic subclass?

A. Class IB
B. Class IC
C. Class IA
D. Class III

A patient started on procainamide develops widening of ventricular depolarization and delayed repolarization. What ECG changes are expected?

A. Prolonged QRS and QT
B. Short PR and QT
C. Narrow QRS only
D. Shortened QRS and QT

Besides Class IA activity, procainamide also has actions resembling which class?

A. Class IV
B. Class II
C. Class IC
D. Class III

Long-term procainamide therapy can produce a syndrome resembling which disease?

A. Rheumatoid arthritis
B. Scleroderma
C. Lupus
D. Myasthenia gravis

Quinidine belongs to which antiarrhythmic subclass?

A. Class IB
B. Class II
C. Class III
D. Class IA

Toxic quinidine levels most classically prolong which ECG interval?

A. QT
B. PR
C. RR
D. ST

A patient on quinidine reports headache, dizziness, and tinnitus. This triad most strongly suggests:

A. Digitalis effect
B. Lupus syndrome
C. Cinchonism
D. Antimuscarinic excess

Which organ system is especially prone to adverse effects from quinidine?

A. Renal
B. GI
C. Pulmonary
D. Endocrine

Compared with other Class IA agents, disopyramide is particularly notable for which additional effect?

A. Strong β blockade
B. Marked vasodilation
C. Pronounced antimuscarinic effects
D. Significant adenosine release

Disopyramide adverse effect?

A. Fecal incontinence
B. Urinary retention
C. Hemoptysis
D. Polyuria

Lidocaine belongs to which antiarrhythmic subclass?

A. Class IA
B. Class IC
C. Class III
D. Class IB

Because of extensive first-pass metabolism, lidocaine used as an antiarrhythmic is typically given:

A. Intravenously
B. Sublingually
C. Intramuscularly
D. Orally

A patient with digoxin toxicity develops ventricular ectopy. Which antiarrhythmic from your material is also used for digitalis-induced arrhythmias?

A. Lidocaine
B. Sotalol
C. Esmolol
D. Dronedarone

Mexiletine belongs to which Vaughan-Williams subclass?

A. Class IA
B. Class II
C. Class IB
D. Class IC

Flecainide belongs to which antiarrhythmic subclass?

A. Class IA
B. Class IB
C. Class III
D. Class IC

Propafenone belongs to which antiarrhythmic subclass?

A. Class IV
B. Class IC
C. Class IB
D. Class IA

Which additional pharmacologic property does propafenone possess?

A. Alpha-blocking activity
B. Muscarinic agonism
C. Beta-blocking activity
D. Nitrate-like vasodilation

Which short-acting β-blocker is specifically used as an antiarrhythmic?

A. Propranolol
B. Carvedilol
C. Sotalol
D. Esmolol

Which β-blocker also has partial Class III antiarrhythmic activity?

A. Nebivolol
B. Sotalol
C. Metoprolol
D. Atenolol

Sotalol predisposes patients to which arrhythmia?

A. Sinus arrest
B. Junctional tachycardia
C. Torsades de pointes
D. Ventricular standstill

Amiodarone is classified primarily as which antiarrhythmic class?

A. Class III
B. Class II
C. Class IA
D. Class IV

Which channel/current is classically blocked by amiodarone?

A. If current
B. IKr
C. INa
D. ICaL

Amiodarone interferes with metabolism of which hormone pathway?

A. T3 to T4
B. TSH to TRH
C. T4 to T3
D. T4 to rT3

A patient on amiodarone also takes warfarin, digoxin, and a statin. Why is close monitoring needed?

A. Amiodarone induces CYP3A4
B. Amiodarone blocks renal secretion
C. Amiodarone inhibits P450 enzymes
D. Amiodarone lowers protein binding

Which Class III drug resembles amiodarone structurally but lacks its effect on thyroid hormone metabolism?

A. Ibutilide
B. Dronedarone
C. Dofetilide
D. Procainamide

Which major toxicity is especially emphasized for dronedarone?

A. Nephrotoxicity
B. Ototoxicity
C. Hepatotoxicity
D. Retinopathy

Dofetilide and ibutilide specifically block which current?

A. INa
B. ICaL
C. IK1
D. IKr

Verapamil and diltiazem belong to which antiarrhythmic class?

A. Class III
B. Class I
C. Class IV
D. Class II

A patient overdoses on verapamil. Which toxic effect is most expected?

A. AV block, severe depression
B. QT shortening, hypertension
C. Reflex tachycardia, tremor
D. Ventricular fibrillation, tremor

Which nucleoside is both a prominent vasodilator and an antiarrhythmic, and is the drug of choice for SVT?

A. Adenosine
B. Atropine
C. Ivabradine
D. Verapamil

What is the mechanism of action of ivabradine?

A. Blocks AV nodal calcium current
B. Blocks IKr in ventricles
C. Blocks If in SA node
D. Inhibits Na/K ATPase

A patient with digitalis-induced arrhythmias needs adjunctive ion therapy. Which is preferred?

A. Calcium
B. Sodium
C. Potassium
D. Magnesium

Which antiarrhythmic from your list can be used to treat Wolff-Parkinson-White syndrome?

A. Verapamil
B. Procainamide
C. Diltiazem
D. Ivabradine