Cardioversion and defibrillation Flashcards
Enhanced automaticity in cardiac tissue can result from which of the following?
A. Increased vagal tone
B. Ischemia or electrolyte imbalances
C. Prolonged refractory period
D. Beta-blocker therapy
Answer: B
Rationale: Ischemia, electrolyte disturbances, and other injuries can increase automaticity and predispose to dysrhythmias.
A patient presents with a narrow complex tachycardia at 170 bpm, stable blood pressure, and no signs of heart failure. The initial management should be:
A. Intravenous beta-blockers
B. Vagal maneuvers
C. Synchronized cardioversion
D. Implantable cardioverter-defibrillator (ICD) placement
Answer: B
Rationale: Stable narrow complex tachycardia is first managed with vagal maneuvers before pharmacologic intervention.
Which dysrhythmia is generally considered benign and can be seen in healthy individuals?
A. Ventricular fibrillation
B. Premature atrial contractions (PACs)
C. Sustained ventricular tachycardia
D. Torsades de pointes
.
Answer: B
Rationale: Occasional PACs are common and usually benign in healthy individuals
What is the typical EKG characteristic of supraventricular tachycardia (SVT)?
A. Wide QRS complexes with ST depression
B. Narrow QRS complexes with a regular rhythm and a rate often above 150 bpm
C. Irregularly irregular rhythm with no discernible P waves
D. Bradycardia with a prolonged PR interval
Answer: B
Rationale: SVT typically presents as a narrow complex, regular tachycardia with rates usually above 150 bpm.
Which of the following is an initial nonpharmacologic intervention for stable SVT?
A. Synchronized cardioversion
B. Intravenous adenosine
C. Vagal maneuvers (e.g., Valsalva maneuver)
D. Immediate defibrillation
Answer: C
Rationale: Vagal maneuvers are first-line for stable SVT, as they can slow AV nodal conduction and terminate the arrhythmia
In unstable patients with SVT (e.g., hypotension, altered mental status), the next step in management is: A. Continue vagal maneuvers
B. Administer adenosine
C. Synchronized cardioversion
D. Initiate beta-blocker therapy
Answer: C
Rationale: Unstable SVT requires immediate synchronized cardioversion to restore a normal rhythm.
Adenosine is used in the management of SVT primarily because it: A. Prolongs the refractory period of the AV node
B. Increases myocardial contractility
C. Blocks sympathetic outflow
D. Acts as a calcium channel blocker
Answer: A
Rationale: Adenosine temporarily blocks conduction through the AV node, interrupting reentrant circuits in SVT.
Which dysrhythmia is characterized by an “irregularly irregular” rhythm with absent P waves on the EKG? A. Atrial flutter
B. Atrial fibrillation
C. Paroxysmal SVT
D. Junctional tachycardia
Answer: B
Rationale: Atrial fibrillation is typically irregularly irregular, with no distinct P waves.
Which treatment is commonly used for rate control in patients with atrial fibrillation?
A. Adenosine
B. Calcium channel blockers (e.g., diltiazem)
C. Procainamide
D. Amiodarone
Answer: B
Rationale: Calcium channel blockers, along with beta blockers, are used to control ventricular rate in atrial fibrillation.
Atrial flutter typically shows a “saw-tooth” pattern on the EKG. Which of the following interventions can be used to slow ventricular response in atrial flutter?
A. Vagal maneuvers
B. Beta blockers
C. Calcium channel blockers
D. All of the above
Answer: D
Rationale: Vagal maneuvers, beta blockers, and calcium channel blockers can all be used to slow AV conduction in atrial flutter.
Which of the following is a potential complication (“what will kill your patient”) of untreated atrial fibrillation?
A. Pulmonary embolism
B. Thromboembolic stroke
C. Ventricular fibrillation
D. Bradycardia
Answer: B
Rationale: Atrial fibrillation increases the risk of thrombus formation in the atria, leading to embolic stroke.
For patients with atrial fibrillation, what is a common “harm” if anticoagulation is not properly managed? A. Systemic embolism
B. Myocardial infarction
C. Bradycardia
D. Hypotension
Answer: A
Rationale: Inadequate anticoagulation in atrial fibrillation increases the risk of embolic events such as stroke.
Which ventricular dysrhythmia is characterized by a uniform, wide QRS complex and may be treated with antiarrhythmic drugs if the patient is hemodynamically stable? A. Ventricular fibrillation
B. Sustained monomorphic ventricular tachycardia
C. Torsades de pointes
D. Sinus tachycardia
Answer: B
Rationale: Sustained monomorphic VT has a uniform QRS morphology and may be managed with drugs like amiodarone if the patient is stable.
If a patient with sustained monomorphic ventricular tachycardia is hemodynamically unstable, the appropriate intervention is: A. Intravenous amiodarone
B. Synchronized cardioversion
C. Vagal maneuvers
D. Observation
Answer: B
Rationale: Unstable VT requires immediate synchronized cardioversion to restore an effective rhythm.
Which medication is considered first-line in treating stable monomorphic VT? A. Adenosine
B. Amiodarone
C. Lidocaine
D. Beta blockers
Answer: B
Rationale: Amiodarone is commonly used for stable monomorphic VT due to its broad-spectrum antiarrhythmic effects.
Torsades de pointes is a form of polymorphic VT often associated with: A. Short QT interval
B. Prolonged QT interval
C. Atrial flutter
D. First-degree AV block
Answer: B
Rationale: Torsades is typically seen in the setting of a prolonged QT interval, which predisposes to this “twisting” ventricular tachycardia.
What is the initial treatment for torsades de pointes in a hemodynamically stable patient? A. Intravenous magnesium sulfate
B. Synchronized cardioversion
C. High-dose beta blockers
D. Immediate defibrillation
Answer: A
Rationale: IV magnesium sulfate is the first-line treatment for torsades de pointes, even if the serum magnesium level is normal.
In pulseless ventricular tachycardia or ventricular fibrillation, what is the first step in management? A. Administration of amiodarone
B. Immediate unsynchronized defibrillation
C. Vagal maneuvers
D. Synchronized cardioversion
Answer: B
Rationale: For shockable rhythms (pulseless VT/VF), immediate defibrillation is indicated per ACLS guidelines.
What distinguishes pulseless electrical activity (PEA) from ventricular fibrillation on the EKG? A. PEA shows organized electrical activity without a mechanical pulse
B. PEA is characterized by chaotic, disorganized electrical activity
C. PEA always presents with a narrow QRS complex
D. PEA demonstrates a “saw-tooth” pattern
Answer: A
Rationale: PEA has organized electrical activity but no effective mechanical heart action; in contrast, VF is disorganized
Which of the following best describes reentry as a mechanism for dysrhythmias?
A. Spontaneous depolarization of normally quiescent cells
B. A short circuit in which an impulse repeatedly travels along a circuitous pathway
C. Blockage of the AV node by high vagal tone
D. Failure of the SA node to generate impulses
Answer: B
Rationale: Reentry involves a circulating impulse reactivating myocardial tissue repeatedly, leading to sustained dysrhythmia.
During synchronized cardioversion for dysrhythmias, why is synchronization important?
A. It minimizes the risk of inducing ventricular fibrillation
B. It increases the energy required for shock delivery
C. It enhances the speed of defibrillation
D. It is only used for bradyarrhythmias
Answer: A
Rationale: Synchronized cardioversion times the shock to avoid the vulnerable T-wave, reducing the risk of inducing VF.
Which reversible causes of PEA and asystole should be assessed during cardiac arrest? A. Hypovolemia, hypoxia, hyperkalemia, and hypothermia
B. Only myocardial infarction
C. Only pulmonary embolism
D. Only drug overdose
Answer: A
Rationale: The “Hs and Ts” (hypovolemia, hypoxia, hyperkalemia, hypothermia, etc.) must be evaluated as reversible causes in PEA/asystole
Which of the following is a common cause (“what is really common”) of ventricular dysrhythmias? A. Acute myocardial ischemia
B. Gastrointestinal bleeding
C. Migraine headaches
D. Hypothyroidism
Answer: A
Rationale: Acute myocardial ischemia is a frequent precipitant of life-threatening ventricular dysrhythmias.
When administering adenosine for SVT, why must the drug be given rapidly?
A. Because it has a long half-life
B. Because it is rapidly metabolized
C. To prevent hypotension
D. To avoid inducing bradycardia
Answer: B
Rationale: Adenosine has a very short half-life, so rapid administration is necessary to achieve effective AV node blockade.
A patient with known structural heart disease develops polymorphic VT. This is most consistent with: A. Stable SVT
B. Torsades de pointes
C. Sinus tachycardia
D. Atrial flutter
Answer: B
Rationale: Polymorphic VT, especially with a twisting QRS pattern, is characteristic of torsades de pointes, often related to prolonged QT.
Which factor could “harm your patient” if misinterpreted during the treatment of dysrhythmias? A. Using adenosine in a patient with atrial fibrillation with rapid ventricular response
B. Correctly identifying the rhythm before treatment
C. Monitoring electrolyte levels
D. Performing vagal maneuvers in stable patients
Answer: A
Rationale: Adenosine is contraindicated in atrial fibrillation as it may worsen the rhythm; misinterpretation can lead to harmful interventions.
Which of the following best describes the term “dysrhythmia”? A. A complete absence of cardiac rhythm
B. A rhythm that is abnormal or dysfunctional
C. A normal sinus rhythm with slight variability
D. A transient pause in the heart rate
Answer: B
Rationale: Dysrhythmia refers to any abnormal or dysfunctional rhythm, rather than simply an absence of rhythm.
Which antiarrhythmic drug is considered a “broad-spectrum” agent for treating ventricular dysrhythmias? A. Adenosine
B. Amiodarone
C. Digoxin
D. Verapamil.
Answer: B
Rationale: Amiodarone is a broad-spectrum antiarrhythmic used in various tachyarrhythmias including VT and VF
In patients with refractory ventricular dysrhythmias, which of the following devices is considered for secondary prevention? A. Temporary pacemaker
B. Implantable cardioverter-defibrillator (ICD)
C. External defibrillator only
D. Beta-blocker pump
Answer: B
Rationale: An ICD is indicated for patients with a history of life-threatening ventricular dysrhythmias to prevent sudden cardiac death
Which electrolyte abnormality is most commonly associated with the development of dysrhythmias? A. Hyperkalemia
B. Hypokalemia
C. Hypercalcemia
D. Hypophosphatemia
Answer: B
Rationale: Hypokalemia is a common electrolyte disturbance that can precipitate various dysrhythmias.
Which condition is “really common” in patients with chronic heart failure and predisposes them to dysrhythmias? A. Enhanced vagal tone
B. Left ventricular remodeling and scar formation
C. Increased parasympathetic activity
D. Improved coronary perfusion
Answer: B
Rationale: Chronic heart failure often leads to remodeling and scar tissue formation, which predisposes patients to reentrant ventricular arrhythmias.
What is the main purpose of obtaining a 12-lead EKG in a patient with suspected dysrhythmia? A. To diagnose electrolyte abnormalities
B. To precisely identify the type of dysrhythmia
C. To measure blood pressure
D. To determine the patient’s weight
Answer: B
Rationale: A 12-lead EKG is essential to classify the dysrhythmia (e.g., SVT, VT, AF, VF) and guide appropriate management.
When managing a patient with pulseless ventricular tachycardia, what is the immediate management step? A. Synchronized cardioversion
B. Immediate defibrillation and initiation of ACLS protocols
C. Vagal maneuvers
D. Administration of adenosine
Answer: B
Rationale: In pulseless VT, immediate unsynchronized defibrillation is mandated as part of ACLS for shockable rhythms.
Which factor is critical to assess when deciding whether a patient with a dysrhythmia is “stable” or “unstable”? A. The patient’s age
B. Hemodynamic status (e.g., blood pressure, level of consciousness)
C. The width of the QRS complex only
D. The presence of a history of dysrhythmias
Answer: B
Rationale: Hemodynamic stability (blood pressure, mental status, signs of shock) is key in determining immediate management (e.g., need for cardioversion).
Which dysrhythmia is most likely to deteriorate into ventricular fibrillation and cause sudden cardiac death? A. Paroxysmal SVT
B. Sustained ventricular tachycardia
C. Sinus bradycardia
D. Atrial flutter
Answer: B
Rationale: Sustained VT can degenerate into ventricular fibrillation, which is a leading cause of sudden cardiac death.
In treating dysrhythmias, which potential iatrogenic harm must be avoided when using electrical cardioversion? A. Underestimating the energy required
B. Delivering unsynchronized shocks leading to R-on-T phenomenon
C. Using adenosine in a pulseless rhythm
D. Administering beta blockers before the shock
Answer: B
Rationale: Unsynchronized shocks can fall on the vulnerable period of the cardiac cycle (T-wave), provoking VF.
What is a common adverse effect of amiodarone therapy that clinicians must monitor? A. Hyperkalemia
B. Hypothyroidism or hyperthyroidism
C. Acute kidney injury
D. Immediate arrhythmia termination without side effects
Answer: B
Rationale: Amiodarone can affect thyroid function, so thyroid monitoring is necessary during chronic therapy.
Which of the following best defines “dysrhythmia” as used in this context? A. The complete absence of electrical activity
B. Any deviation from the normal organized electrical rhythm of the heart
C. A benign sinus rhythm with occasional ectopic beats
D. The electrical pattern seen in a healthy athlete
Answer: B
Rationale: Dysrhythmia refers to any abnormal or disordered electrical rhythm, which may be benign or life-threatening.
Which of the following scenarios is most concerning (“what will kill your patient”) if left untreated? A. Atrial fibrillation with controlled rate in an asymptomatic patient
B. Sustained polymorphic VT (torsades de pointes) leading to hemodynamic collapse
C. Occasional premature atrial contractions
D. Sinus tachycardia due to fever
Answer: B
Rationale: Sustained torsades de pointes is life-threatening and can deteriorate into VF, resulting in cardiac arrest.
Which environmental or pharmacologic factor can precipitate dysrhythmias by altering electrolyte balance? A. High dietary fiber intake
B. Diuretic overuse leading to hypokalemia
C. Excessive water consumption
D. Routine exercise
Answer: B
Rationale: Overuse of diuretics may cause hypokalemia, a known precipitant of dysrhythmias.
In patients with ventricular dysrhythmias, why is it important to identify and treat reversible causes? A. They usually resolve on their own
B. They may be corrected to prevent recurrence and further cardiac arrest
C. They do not affect long-term management
D. Reversible causes are rare and not important
Answer: B
Rationale: Addressing reversible causes (electrolyte imbalances, ischemia, drug toxicity) is essential to prevent recurrent, potentially fatal dysrhythmias
Which of the following is a common physical examination finding in patients with dysrhythmias? A. A regular, slow pulse
B. Palpitations or irregular pulse rhythms
C. A completely silent heart on auscultation
D. A continuous murmur over the carotids
Answer: B
Rationale: Patients often report palpitations and may have an irregular pulse, especially in atrial fibrillation
Which of the following EKG findings is most typical in ventricular fibrillation? A. Regular, narrow QRS complexes
B. Chaotic, irregular electrical activity with no discernible QRS complexes
C. Organized, wide QRS complexes
D. Normal sinus rhythm
Answer: B
Rationale: Ventricular fibrillation is characterized by chaotic electrical activity without organized QRS complexes, leading to no effective cardiac output.
When managing dysrhythmias, what is the primary rationale for using beta blockers in stable patients? A. They increase heart rate and contractility
B. They decrease sympathetic tone, reducing automaticity and conduction velocity
C. They act as potent vasodilators
D. They have no effect on the conduction system
Answer: B
Rationale: Beta blockers reduce sympathetic stimulation, which helps control heart rate and reduce arrhythmic potential.
In atrial fibrillation, what is the common complication if a patient is not appropriately anticoagulated? A. Ventricular tachycardia
B. Systemic embolization, particularly stroke
C. Atrial flutter
D. Sinus bradycardia
Answer: B
Rationale: Inadequate anticoagulation in atrial fibrillation increases the risk of clot formation in the atria and subsequent embolic stroke.
Which scenario would be classified as an unstable dysrhythmia requiring immediate intervention? A. SVT with a heart rate of 160 bpm in a fully alert patient
B. Atrial fibrillation with rapid ventricular response in a patient with hypotension and altered mental status
C. Occasional premature ventricular contractions
D. Sinus tachycardia due to exercise
Answer: B
Rationale: Dysrhythmias causing hypotension, altered mental status, or signs of shock are unstable and necessitate urgent treatment.
What is the potential harm (“what will harm your patient”) of administering adenosine in the wrong clinical scenario? A. It can cause profound bradycardia or even asystole in patients with underlying conduction system disease
B. It always terminates atrial fibrillation
C. It has no side effects
D. It is contraindicated only in ventricular dysrhythmias
Answer: A
Rationale: Adenosine can provoke severe bradycardia or asystole if used inappropriately, particularly in patients with preexisting conduction abnormalities.
Which of the following best summarizes the management principles for dysrhythmias? A. Always use electrical therapy first regardless of stability
B. Rapid identification, risk stratification (stable vs. unstable), addressing reversible causes, and using appropriate pharmacologic or electrical therapies based on the specific rhythm
C. Sole reliance on antiarrhythmic drugs without monitoring hemodynamics
D. Delaying treatment until all diagnostic tests are complete
Answer: B
Rationale: Management of dysrhythmias requires timely diagnosis, determination of stability, correction of reversible causes, and selecting the appropriate therapy (vagal maneuvers, medications, or cardioversion) based on the rhythm and patient status.
Which EKG finding is most concerning for impending ventricular fibrillation?
A. Regular, narrow QRS complexes
B. Rapid, monomorphic ventricular tachycardia
C. Polymorphic ventricular tachycardia with twisting of QRS complexes (Torsades de Pointes)
D. Sinus rhythm with premature atrial contractions
Answer: C
Rationale: Torsades de pointes is a form of polymorphic VT associated with prolonged QT interval and can degenerate into VF, making it life-threatening if not treated promptly.
Which scenario is considered an “unstable” dysrhythmia requiring immediate synchronized cardioversion?
A. SVT with a rate of 160 bpm in a patient who is asymptomatic
B. Atrial fibrillation with rapid ventricular response in a patient with hypotension and altered mental status
C. Occasional PVCs in a patient with a normal blood pressure
D. Sinus tachycardia secondary to fever
Answer: B
Rationale: Atrial fibrillation with rapid ventricular response in a patient with signs of hemodynamic instability (hypotension, altered mental status) is unstable and requires immediate cardioversion.
Which of the following is a potential iatrogenic harm when administering synchronized cardioversion?
A. Ensuring the patient is well-sedated
B. Delivering a shock unsynchronized, causing R-on-T phenomenon and potential induction of VF
C. Using a defibrillator with proper synchronization
D. Confirming the rhythm is shockable
Answer: B
Rationale: Unsynchronized shocks (R-on-T phenomenon) during cardioversion can provoke ventricular fibrillation, which is life-threatening.
Which electrolyte disturbance is most commonly associated with an increased risk of dysrhythmias?
A. Hypercalcemia
B. Hypokalemia
C. Hypernatremia
D. Hypomagnesemia
Answer: B
Rationale: Hypokalemia is a well-known precipitant of various dysrhythmias by increasing myocardial excitability and abnormal conduction
A patient with chronic heart failure presents with new-onset palpitations and an irregularly irregular rhythm on EKG. What is the most likely diagnosis?
A. Atrial fibrillation
B. Atrial flutter
C. Paroxysmal SVT
D. Ventricular tachycardia
Answer: A
Rationale: An irregularly irregular rhythm without distinct P waves is characteristic of atrial fibrillation, which is common in patients with chronic heart failure.
Which antiarrhythmic medication is considered first-line for treating stable monomorphic VT?
A. Adenosine
B. Amiodarone
C. Verapamil
D. Digoxin
Answer: B
Rationale: Amiodarone is broadly effective for ventricular arrhythmias, particularly stable monomorphic VT, due to its multiple mechanisms of action.
In the management of torsades de pointes, why is magnesium sulfate administered even if serum magnesium is normal?
A. It acts as a direct inotrope
B. It shortens the QT interval and stabilizes myocardial membranes
C. It increases heart rate
D. It directly dissolves the abnormal electrical circuits
Answer: B
Rationale: Magnesium sulfate is used to reduce the incidence of torsades de pointes by shortening the QT interval and stabilizing the myocardium, independent of serum levels.
What is the most common cause of dysrhythmias in patients with myocardial ischemia?
A. Enhanced vagal tone
B. Reentry circuits due to scar formation and ischemic injury
C. Increased blood volume
D. Hyperthyroidism
Answer: B
Rationale: Ischemic injury leads to scar formation and conduction heterogeneities, promoting reentrant circuits that cause dysrhythmias.
When evaluating a patient with suspected dysrhythmia, which diagnostic tool is fundamental?
A. Chest X-ray
B. 12-lead EKG
C. Echocardiography
D. Cardiac MRI
Answer: B
Rationale: A 12-lead EKG is the primary tool for identifying and classifying dysrhythmias, guiding further management.
Which of the following best explains the term “automaticity” in cardiac conduction?
A. The heart’s ability to slow down conduction
B. The capacity of cardiac cells to spontaneously depolarize without external stimulus
C. The forced depolarization of the myocardium via pacing
D. The conduction delay between atria and ventricles
Answer: B
Rationale: Automaticity refers to the intrinsic ability of cardiac cells, particularly in the SA node, to generate impulses without external provocation
In the setting of dysrhythmia management, which factor distinguishes atrial flutter from atrial fibrillation on an EKG?
A. Irregularly irregular rhythm
B. Saw-tooth pattern of atrial activity
C. Absence of QRS complexes
D. Prolonged PR interval
Answer: B
Rationale: Atrial flutter typically presents with a saw-tooth pattern on the EKG, in contrast to the irregularly irregular pattern of atrial fibrillation.
What is the key purpose of synchronized cardioversion in dysrhythmia management?
A. To induce a pause in the cardiac cycle
B. To deliver a shock that is timed with the R wave, avoiding the T-wave
C. To increase myocardial contractility immediately
D. To stimulate automaticity of the SA node
Answer: B
Rationale: Synchronized cardioversion delivers a shock during the R wave to avoid the vulnerable T-wave period, reducing the risk of inducing VF
When considering pharmacologic treatment for dysrhythmias, why is it essential to first assess and manage electrolyte imbalances?
A. Electrolyte imbalances can mask underlying dysrhythmias
B. They may exacerbate or precipitate dysrhythmias, and correction can improve rhythm stability
C. They determine the need for synchronized cardioversion
D. They directly measure myocardial oxygen consumption
Answer: B
Rationale: Electrolyte disturbances, such as hypokalemia or hypomagnesemia, can precipitate dysrhythmias; correcting these imbalances is a crucial step in management.
Which dysrhythmia is considered a common cause of sudden cardiac death and requires immediate defibrillation when pulseless?
A. Atrial fibrillation
B. Ventricular fibrillation
C. Paroxysmal SVT
D. Sinus tachycardia
Answer: B
Rationale: Ventricular fibrillation is a chaotic rhythm without effective cardiac output and is the leading cause of sudden cardiac death, requiring immediate defibrillation.
A patient with dysrhythmia is being treated with amiodarone. Which long-term side effect should be monitored?
A. Renal failure
B. Thyroid dysfunction
C. Peripheral neuropathy
D. Hypotension
Answer: B
Rationale: Amiodarone is associated with thyroid dysfunction (both hypo- and hyperthyroidism) as a long-term side effect.
