Cardiac Electrophysiology Flashcards
What is the most common mechanism involved in clinically important cardiac
arrhythmias?
Triggered activity
Abnormal automaticity
Reentry
Early afterdepolarizations
Parasystole
Reentry is the most common mechanism underlying cardiac tachyarrhythmias, including
AVNRT, atrial flutter, AVRT with an accessory pathway, and VT in a diseased heart.
Torsades de pointes is characterized by all of the following except:
Results from triggered activity (early afterdepolarizations) that occurs during phase 2 or 3 of the cardiac action potential
Prolonged QT interval
Exacerbation by bradycardia with short-long coupling intervals
Polymorphic VT
Often provoked during amiodarone administration
Torsades de pointes is characterized by prolonged QT intervals, exacerbation by bradycardia, short-long couple intervals, “salvos” of nonsustained polymorphic VT before degeneration into a sustained ventricular arrhythmia, and polymorphic VT with characteristic “twisting around the axis” morphology. Although amiodarone often prolongs the QT interval, it rarely causes torsades de pointes.
Which one of the following currents is responsible for maintaining stable resting membrane potential in the atrial and ventricular cells?
a. If b. INa c. IKl d. IK e. ICa
IK1 (inward rectifier) is crucial for maintaining the resting potential near
The IKATP is a potassium channel that is inhibited by physiologic intracellular concentrations of ATP. How is this channel activated?
A consequence of If activation that enhances pacemaker activity
Physical opening of the channel pore by the N-terminal portion of the
channel
Chemical ligand binding in response to depletion of ATP from ischemia
Conformational changes in channel structure
The channel is only inhibitory and is not activated
The IKATP potassium channel is inactivated by chemical ligand binding in response to ischemia and depletion of ATP. Ventricular myocytes have high densities of these chan- nels and their activation accounts for the ST elevation on the ECG seen during a MI.
The sinus node is predominantly characterized by depolarization in which phase of the action potential?
Phase 0
Phase 1
Phase 2
Phase 3
Phase 4
The sinus node is predominantly characterized by its phase 4 depolarization, which accounts for the pacemaker activities. There are few sodium channels and the upstroke is primarily mediated by ICa,L. There is no discernible phase 1. The lack of IK1, which is active in phase 3, accounts for the relative depolarized state of the tissue.
Which one of the following antiarrhythmic agents does not prolong the QT interval?
a. Quinidine
b. Lidocaine
c. Sotalol
d. Procainamide e. Ibutilide
- Answer b.
Lidocaine is a weak sodium channel blocker and does not have significant potassium channel blockade. It does not prolong the QT and it is the one antiarrhythmic that may actually shorten it.
Which one of the following antiarrhythmic agents has the least effect on slowing conduction through the AV node?
Calcium channel blockers
Beta blockers
Amiodarone
Lidocaine
Sotalol
Lidocaine is a rather specific sodium channel blocker. The AV node conduction is mediated by ICa,L. The AV node is similar to the sinoatrial node in its lack of INa. Lidocaine does not have a significant effect on AV nodal conduction.
Which of the following antiarrhythmic agents may promote AF?
a. Adenosine b. Quinidine c. Propafenone d. Amiodarone e. Atenolol
Adenosine activates the IK,Achchannel in atrial tissue. Activation of the IK,Achchannel shortens the action potential duration, thereby shortening the refractoriness of the atrial tissue and promoting the induction of AF.
Which one of the following antiarrhythmic agents is least likely to cause torsades de pointes?
Quinidine
Procainamide
Flecainide
Ibutilide
Sotalol
Of the answer choices given, class 1A agents (quinidine and procainamide) and class 3 agents (ibutilide and sotalol) have a significant potassium channel blocking effect, there- fore prolonging the QT interval and potentially causing torsades de pointes. Flecainide (a class 1C agent) is a fairly specific sodium channel blocker without a significant potas- sium channel blocking effect. Prolongation of the QT interval is not associated with flecainide.
All of the following statements regarding the AV node are true except:
Conduction through the node displays decremental behavior
It is positioned in the subendocardium at the base of the triangle of Koch
It is composed of nodal cells and transitional cells
It is a right atrial structure
The AV node is positioned in the low RA at the apex, rather than the base, of the tri- angle of Koch. The triangle of Koch is comprised of the ostium of the CS, tendon of Todaro, and septal attachment of the tricuspid valve leaflet. The region within the tri- angle is comprised of nodal and transitional cells.
In which of the following tissues is the upstroke of the action potential generated by ingoing calcium currents?
a. Atrial
b. AV node
c. His-Purkinje
d. Ventricular
Both the AV and sinoatrial nodal cells lack INa. Conduction is mediated in these tissues by ICa,L.
Conduction velocity is most rapid in which tissue?
a. Atrial
b. AV node
c. His-Purkinje
d. Ventricular
The conduction velocity is the most rapid in the His-Purkinje tissue.
Repolarization of the myocardial cells is determined mostly by which current?
Outgoing sodium
Ingoing calcium
Outgoing potassium
Ingoing chloride
Ingoing sodium
The outgoing potassium current is the principal determinant of repolarization of myocardial cells.
All of the following statements regarding AV nodal cells are true except:
a. The resting membrane potential is typically
The resting membrane potential of AV nodal cells is
Vagal stimulation in each of the following tissue types changes the action poten- tial duration except in which cardiac structure?
AV node
His-Purkinje system
Ventricular myocardium
Atrial myocardium
Vagal stimulation has little effect on the ventricular myocardial action potential, whereas it increases the action potential in the AV node and reduces it in the atrial myocardium.
Early afterdepolarizations are favored by:
High potassium concentrations
Type III antiarrhythmic drugs
Fast underlying HR
Increased magnesium concentrations
Early afterdepolarizations are depolarizations that occur in phases 2 and 3 of the action potential. Conditions that prolong the action potential duration promote the development of early afterdepolarizations. They are facilitated by a low potassium level, low magnesium level, and class I or III antiarrhythmic drugs, and are typically pause-dependent.
The underlying arrhythmia mechanism most likely present in digitalis toxicity is:
Reentry
Delayed afterdepolarizations
Enhanced automaticity
Early afterdepolarizations
The mechanism that underlies the development of delayed afterdepolarizations is intracellular calcium overload. Digoxin increases intracellular calcium that can pro- mote delayed afterdepolarization-triggered activity. Delayed afterdepolarizations have also been implicated in ischemic reperfusion arrhythmias and ryanodine receptor dys- function.
Which of the following contain the normal A–H and H–V intervals?
40–80 msec, 35–60 msec
60–120 msec, 35–60 msec
60–120 msec, 25–50 msec
60–100 msec, 60–80 msec
60–120 msec, 35–60 msec
Patients with the Wolff-Parkinson-White syndrome typically show each of the following features except:
A wide QRS complex during normal sinus rhythm
A narrow complex SVT
A delta wave on the surface QRS
A long H–V interval on the His-bundle recording
The H–V interval in Wolff-Parkinson-White syndrome can be negative or very short with antidromic tachycardia because the ventricle is activated prematurely by the accessory pathway or normal in orthodromic tachycardia since conduction proceeds down the AV node to the ventricle and returns retrograde through an accessory pathway. The more typical form of Wolff-Parkinson-White syndrome is orthodromic and the QRS is narrow, even in tachycardia, unless functional bundle branch block occurs since the antegrade conduction proceeds through the AV node and His-Purkinje system.
Prerequisite conditions of the reentrant arrhythmia include all of the following except:
Two functionally distinct conducting pathways
An anatomical obstacle around which the impulse reenters
Unidirectional block in one pathway
Slow conduction via one pathway with return via the second
An anatomical obstacle is not necessary for reentrant arrhythmia. Recent studies have shown that reentry can occur in the absence of an obstacle as a consequence of con- duction and refractoriness in the atrial or ventricular tissue.
Antidromic reciprocating tachycardia in a patient with Wolff-Parkinson-White refers to:
AV conduction proceeding via the normal AV conduction system with return via the accessory pathway
AV conduction via the accessory pathway with return via the normal ven- triculoatrial conduction system
AVNRT with additional conduction via the accessory pathway
None of the above
In antidromic reciprocating tachycardia, conduction is “anti” the normal path through the AV node. Thus there is AV conduction via the accessory pathway with the return ventriculoatrial conduction via His-Purkinje system followed by the AV node.
The most common mechanism of arrhythmia in sustained VT is:
Sympathetically facilitated enhanced automaticity
Reentry involving ventricular myocardium
Triggered automaticity arising from early afterdepolarizations
Reflection of propagated impulses
The most common mechanism of arrhythmias in sustained VT is reentry involving ventricular myocardium, most often from scars due to underlying CAD.
A 54-year-old man is referred to you due to an enlarged cardiac silhouette dis- covered on routine chest X-ray as part of his employment physical exam. He reports no known past medical history. Although he denies symptoms of overt heart failure, he states that he tends to become short of breath with strenuous activity—a symptom that he felt was due to lack of exercise.
On physical examination he has a displaced apical impulse and a third heart sound. An ECG shows sinus rhythm with a LBBB. An echocardiogram discloses global LV dysfunction with an EF of 25% and mild functional mitral valve regurgi- tation. Coronary angiography is normal. A 24-hour Holter monitor shows 35,000 PVCs and 85 runs of nonsustained VT, 3 to 9 beats in duration.
What is the next appropriate test?
EP study
RV biopsy
Serum ferritin
Signal average ECG
No further testing is required; schedule the patient to receive an ICD
The patient has nonischemic cardiomyopathy and a search for potential secondary causes is warranted. Noninvasive testing, such as obtaining a serum ferritin to assess for hemochromatosis, should be performed prior to invasive studies, such as RV biopsy. In a minimally symptomatic patient, an EP study is not a first line test. Nonetheless, if the PVCs are monomorphic and other causes of cardiomyopathy are excluded, the patient may be considered for an EP study and attempted ablation of the focus. Prior to considering an ICD in this patient who has no other significant symptoms, medical therapy needs to be started and titrated to therapeutic doses.
All of the following clinical characteristics are associated with cardiogenic syn- cope and should prompt referral for an invasive EP study except:
Age
Answers a to d are all considered high risk characteristics for cardiogenic syncope. If any of these are present, the rate of spontaneous ventricular tachyarrhythmia or death is between 4% and 7% in 1 year. If 3 or more are present, this rate increases to 58% to 80%. Recurrent unexplained falls in an elderly patient should first be assessed with tilt table testing unless other high risk features are present.
A 38-year-old man underwent radiofrequency ablation in the RA for medically refractive symptomatic atrial tachycardia. He was dismissed on aspirin 325 mg/day. Six days following the procedure he developed left-sided persistent chest pain and mild dyspnea. His exam is notable only for tachycardia with a HR of 110 bpm. An ECG discloses sinus tachycardia. What is the next most appropriate test to request?
Echocardiogram
CT scan
Coronary angiography
Arterial blood gas, D-Dimer
Ventilation perfusion scan
The temporal presentation and symptoms of the patients are consistent with pulmonary embolism, complicating the EP study he had 6 days before. The next step is to assess for this complication with screening tests, such as an arterial blood gas and D-Dimer, fol- lowed by an imaging modality, such as a ventilation perfusion scan or CT scan. If the evaluation for a pulmonary embolus is negative, a next step is to consider pericarditis.
All the following are true about head-up tilt testing except:
The test should be performed at 60 to 80 degrees
Sensitivity and specificity of the test are approximately 80%
A vasodepressor response occurs most often in patients younger than 60
In patients without structural heart disease, it can provide a diagnosis in approximately 60% of them
A cardioinhibitory response tends to be infrequent in older patients
Vasodepressor response characterized by a profound drop in BP with minimal change in HR is more common in patients more than 60 years old. In contrast, cardioinhibitory response characterized by asystole and profound bradycardia that coincides with a decrease in BP, or a mixed-type event that is a combination of HR and BP reduction, is the initial event occurring more often in younger patients.
The arrhythmic substrate least likely to be definitely ruled out with a negative EP study is:
Sinus node dysfunction
Severe His-Purkinje disease
Accessory bypass tract
VT in a patient with ischemic cardiomyopathy
AVNRT
The sensitivity of EP testing for sinus node disease is
An active 78-year-old woman with recurrent syncope has an EP study. With atrial pacing at 150 bpm for 30 sec, a 7-sec atrial pause occurs when the pacing ceases. Her baseline examination and echocardiogram are all within normal limits. ECG shows sinus rhythm with first degree AV block. What is the next appropriate management step?
Implant a VVI single-chamber permanent pacemaker
Implant a dual-chamber ICD
Implant a DDDR dual-chamber rate responsive pacemaker
Implant an AAI single-chamber permanent pacemaker
Medical management with atropine
The patient has recurrent syncope with evidence of significant sinus node dysfunction. In this patient a pacemaker is indicated. The choices of therapy include an AAI versus a DDDR permanent pacemaker. AAI is indicated in a patient when AV conduction is completely normal. If there is evidence of dysfunction, such as this patient with first degree AV block, DDDR is the generally agreed upon treatment.
Programmed ventricular stimulation is an important tool in risk assessment in patients with CAD for which of the following patient subsets?
An EF of 30% to 35% and the presence of nonsustained VT
An EF of 35% to 40% and the presence of nonsustained VT
An EF of 30% to 35% and an abnormal signal averaged ECG
An EF of 35% to 40% and a history of cardiac arrest
MUSTT showed that patients with an EF
All of the following examples are considered positive responses to a drug in a patient with an expected cardiac channelopathy except:
A decreased QT interval with lidocaine in a patient suspected to have long QT3
An increased QT interval with epinephrine in a patient suspected to have
long QT1
Abnormal ST-T changes in leads V1–V2 with procainamide in a patient
suspected to have Brugada syndrome
AnincreasedQTintervalwithnotchedTwaveswithepinephrineinapatient
suspected to have long QT2
An increased QT interval with ajmaline in a patient suspected to have
long QT4
Answers a to d are all considered a positive response to pharmacologic stress in patients suspected to have a cardiac channelopathy. Ajmaline is a sodium channel blocking agent used in patients suspected to have Brugada syndrome.
Acute success rates for ablation of accessory pathways could be stated as:
50% to 70%
75%
85%
90% to 95%
Virtually 100%
Acute success rates for accessory pathway ablation in Wolff-Parkinson-White syndrome are approximately 90% to 95%. Right-sided pathways tend to have lower acute success rates in comparison to left-sided pathways.
The following findings are considered positive results during EP testing except:
A
An H–V interval from 55 to 99 msec is considered an intermediate result and requires either the presence of additional symptoms or other findings to direct therapy. An H–V interval
A patient has a loss of function mutation in KCNQ1. This patient is most likely to have events triggered by:
Swimming
Doorbells
The postpartum period
Sleeping
The vast majority of long QT cases are due to mutations in the KCNQ1 gene that encodes the slow component of the delayed rectifier potassium current (long QT1). During exercise these patients fail to shorten their QT. The gene-specific triggers of patients with long QT1 are exertion-related activities, in particular swimming. In long QT2 auditory stimuli and the postpartum period are important triggers. In long QT3 the most common trigger is sleep.
Efforts to identify patients with concealed long QT syndrome (genotype positive and resting ECG negative) are improved by which testing and response?
Exercise testing with failure to lengthen the QT interval appropriately
ParadoxicallengtheningoftheQTintervalwithlow-doseepinephrineinfusion
EP testing with induction of polymorphic VT with ventricular extra stimuli
Nofurthertestingisrequiredinthesepatientsunlesstheyexperiencesyncope
Paradoxical lengthening of the QT with low-dose epinephrine (
Efforts to identify patients with concealed long QT syndrome (genotype positive and resting ECG negative) are improved by which testing and response?
Exercise testing with failure to lengthen the QT interval appropriately
ParadoxicallengtheningoftheQTintervalwithlow-doseepinephrineinfusion
EP testing with induction of polymorphic VT with ventricular extra stimuli
Nofurthertestingisrequiredinthesepatientsunlesstheyexperiencesyncope
Paradoxical lengthening of the QT with low-dose epinephrine (
Which of the following sports can be played in patients with long QT syndrome?
Golf
Cricket
Bowling
Billiards
All of the above
According to the 2005 Bethesda Conference guidelines, competitive sports are restricted with the exception of class IA activities. These activities include: golf, cricket, bowling, billiards, and riflery.
Each of the following statements about Romano-Ward syndrome is true, except:
It is a heterogeneous disorder involving mutations in different ion channels
It is inherited as an autosomal recessive disorder
It is associated with sudden cardiac death in young patients
It is not associated with congenital deafness
It is more frequent than the Jervell and Lange-Nielsen syndrome
All of the above statements are true except b. Romano-Ward syndrome is a heteroge- neous disorder associated with prolonged QT interval and recurrent syncope, cardiac arrest, or sudden death. It is inherited in an autosomal dominant pattern and several mutations involving sodium and potassium channels have been recognized. Jervell and Lange-Nielsen syndrome is inherited in an autosomal recessive pattern. It is associated with prolonged QT interval, history of recurrent syncope or sudden death, and con- genital neural deafness. The Romano-Ward syndrome is more frequent than the Jervell and Lange-Nielsen syndrome.
Treatments of drug-induced prolongation of QT interval and torsades de pointes include all of the following except:
Withdrawal of the offending agent
Correction of electrolyte and acid-base disturbance
IV magnesium
IV isoproterenol infusion or temporary pacing
IV beta blocker
All of the given statements, except e, are true in the management of drug-induced QT prolongation. Both isoproterenol infusion and temporary pacing can be used to increase the baseline HR. Beta blockers, which have a role in reducing arrhythmias in long QT1 and 2, are not effective in drug-induced tachyarrhythmia, and could worsen the condi- tion by promoting bradyarrhythmia and pauses.
All of the following medications are known to prolong the QT interval and potentially cause torsades de pointes except:
Amiodarone
Erythromycin
Haloperidol
Sotalol
None of the above
All the medications listed in answers a to d have been shown to increase the QT inter- val. Although Amiodarone is on the list of agents that prolong the QT interval, it rarely causes torsades de pointes. Nonetheless, this potential complication must be considered. For a complete list of drugs that are known to cause this complication see www.torsades.org or www.qtdrugs.org
Which of the following disorders results from alterations of intracellular calcium release from the sacroplasmic reticulum?
Catecholaminergic polymorphic VT
Short QT syndrome
Long QT syndrome
Andersen-Tawil syndrome
Romano-Ward syndrome
Mutations in the RyR2-encoded cardiac ryanodine receptor or the calcium release channel account for the majority of catecholaminergic polymorphic VT cases. These mutations result in increased calcium leak during sympathetic stimulation, particu- larly during diastole.
Symptomatic patients diagnosed with mutations in the RyR2-encoded cardiac
ryanodine receptor should receive what first line therapy?
Calcium channel blocker
Beta blocker
ICD
Amiodarone
Surgical myectomy
Patients with symptomatic catecholaminergic polymorphic VT should receive an ICD as first line therapy since other therapies, such as calcium channel and beta blockers, have not been shown to be sufficiently protective.
A 16-year-old male presents to you after a screening ECG was performed for a sports physical that demonstrated pre-excitation. What is the next step in his evaluation?
EP testing and ablation of the accessory pathway
Echocardiogram
No further evaluation is required
Empiric treatment with a beta blocker
None of the above
In patients with manifest pre-excitation, an echocardiogram should be performed since the incidence of associated congenital heart disease can be a high as 30% in some series. The most common associated congenital heart disease is Ebstein anomaly. Furthermore, an echocardiogram allows assessment of LV function, which is often depressed after conversion from a SVT. Finally, exercise testing can be considered as a further means to assess risk. Exercise provides information regarding the accessory pathway and its con- duction at higher HRs. Disappearance of the delta wave with exercise has been reported to coincide with a low risk of sudden death.
A common form of SVT in teenagers is:
Atrial ectopic tachycardia
Atrial flutter
Junctional ectopic tachycardia
AVNRT
Familial AF
AVNRT is a rare form of SVT in infants, but gradually increases with time. In teenagers, this rhythm and accessory-pathway mediated tachycardia account for nearly 95% of the SVT cases. AVNRT is more common in females. All the other arrhythmias listed are uncommon in this age group.
In the pediatric population, which of the following cardiac diseases is associated with second degree AV block?
Tumor (rhabdomyoma)
Myopathy (Duchenne muscular dystrophy)
Immunologic (maternal systemic lupus erythematosus)
Long QT syndrome
All of the above
All of the answer choices a to d are associated with second degree AV block. Regarding long QT syndrome, a subgroup of infants with this channelopathy present with 2:1 AV block due to His-Purkinje system or ventricular myocardial refractoriness. Other causes of second degree AV block include mechanical trauma during catheterization, meta- bolic, and drug induced etiologies.
All of the following are reasons to consider implanting a permanent pacemaker in a patient with congenital third degree AV block except:
Declining exercise performance
Junctional instability or wide QRS escape rhythm
Progressive cardiomyopathy with declining ventricular performance
QT prolongation
Persistent third degree AV block after isoproterenol infusion
Answers a to d are all reasons to implant a permanent pacemaker in a patient with congenital AV block. An additional reason is
Typical mechanisms associated with the initiation and maintenance of AF include all of the following except:
Substrate abnormalities that permit and promote wavelet reentry
Autonomic nervous system
Focal rapidly discharging triggers
Dual AV node physiology
Dual AV node physiology provides the substrate for typical AVNRT. Answers a to c are proposed mechanisms underlying the initiation and maintenance of AF.
Risk factors associated with AF include all of the following except:
HTN
Sick sinus syndrome
Obstructive sleep apnea
Wolff-Parkinson-White syndrome
None of the above
Each of answers a to d has been shown to be a risk factor for AF. Other established causes include advancing age, valvular heart disease, excessive alcohol intake, thyro- toxicosis, pericarditis, cardiac surgery, acute pulmonary disease, and MI.
The major finding of the AFFIRM trial was which of the following?
Rhythm control patients were more likely to live longer and experience an improved quality of life
Rate control patients were less likely to develop heart failure
Patients
The AFFIRM trial studied 4,060 patients older than 65 years with a history of AF and additional risk factors for stroke or death. They were randomized to either rate control or rhythm control. Patients in the rhythm control group were more likely to be in sinus rhythm. However, there was no statistically significant difference in mor- tality, stroke, quality of life, or development of heart failure between the rate and rhythm control groups.
AFFIRM trial type patients that are placed on an antiarrhythmic agent and are maintained in sinus rhythm can stop their anticoagulation. True or false?
a. True
b. False
False. One of the most important findings in the AFFIRM trial was that anticoagulation should be strongly considered in these patients even in the presence of sinus rhythm. One reason is that these patients often have silent or subclinical AF. The second reason is that AF is often associated with many other medical comorbidities that increase stroke risk, such as HTN, diabetes, CAD, heart failure, etc.
Risk factors for stroke in patients with AF include all of the following except:
Age
Risk factors with AF can be remembered with the CHADS2 mnemonic, which stands for: C, cardiac failure; H, hypertension; A, age
Adequate rate control in a patient with AF is defined as:
Resting HR
Adequate rate control in patients with AF is defined as a resting HR
In patients with heart failure, the following antiarrhythmic drug options are acceptable:
Amiodarone
Flecainide
Dofetilide
Bothaandc
All of the above
Dofetilide and amiodarone are acceptable drug choices in patients with AF and heart failure.
A 56-year-old male with HTN presented with palpitations and dyspnea with exertion. He is unsure when the symptoms started, but feels he has had a gradual decline over a one week period. He takes HCTZ for his HTN. He has no other known medical history. His systolic BP is 170 mmHg and the diastolic pressure is 80 mmHg. An ECG reveals AF with a rapid ventricular rate at 120 bpm.
All of the following are acceptable options in his subsequent care except:
Initiate anticoagulation, add a rate control medication, and return for car- dioversion in 3 weeks
Initiate anticoagulation, perform a TEE, and, if negative for an intracardiac thrombus, proceed with DC cardioversion
Initiate anticoagulation, start amiodarone
Initiate anticoagulation, add a ratec ontrol medication, and aggressively improve
his BP treatment
Direct interventions to restore sinus rhythm, such as DC cardioversion or starting an antiarrhythmic, should be avoided in this patient with AF
PAF is associated with a decreased risk of stroke compared with chronic AF. True or false?
a. True
b. False
False. Randomized studies of nonrheumatic AF in patients with paroxysmal and chronic AF have shown no difference in the rate of stroke between the subgroups. First, patients with AF often have other comorbidities that are associated with a higher risk of stroke. Also, recent studies of different therapies have documented that patients typi- cally experience multiple subclinical or asymptomatic episodes of AF. These patient characteristics may account in part for why there is little difference in stroke risk between these arrhythmia subtypes.
A 56-year-old man presents with an 8-day history of palpitations. He has known PAF and takes warfarin. His INR levels have been consistently therapeutic. His systolic BP is 128 mmHg. His exam is normal. An ECG shows AF with rapid ventricular rate of 115 bpm. It is appropriate to initiate therapy with all the fol- lowing medications except:
a. Digoxin
b. Diltiazem
c. Procainamide
d. Metoprolol
Digoxin, diltiazem, and metoprolol will slow the AV node conduction and control the ventricular rate. Although procainamide can be used to restore normal sinus rhythm, it enhances AV node conduction and may result in an increase in ventricular rate. Therefore, rate control should be achieved before initiating procainamide.
A relatively healthy 60-year-old patient presents with persistent PAF despite, first, a trial of propafenone, and now amiodarone. All of the following approaches are appropriate except:
Left atrial ablation to isolate the pulmonary veins
AV node ablation with implantation of a permanent pacemaker
Rate control only if relatively asymptomatic during the episodes of AF
Investigate for obstructive sleep apnea and treat if present
None of the above
Answers a to d are all appropriate for a patient who presents with persistent AF despite the use of an antiarrhythmic agent. The patient requires anticoagulation and needs treat- ment of HTN and obstructive sleep apnea if present. AV node ablation remains a highly successful means of long-term rate control, but the patient requires long-term pacemaker dependency with RV pacing. Left atrial ablation has emerged as a highly successful alter- native to drug therapy for rhythm control.
Radiofrequency catheter ablation of AF is characterized by all of the following except:
The approach is more successful in patients with PAF in comparison to chronic AF
Risks include pulmonary vein stenosis, cardiac perforation, atrial esophageal fistula formation, and stroke
In the majority of patients, the procedure is successful in restoring sinus rhythm and improving quality of life
Anticoagulation can be stopped in these patients after 3 months if they remain in sinus rhythm
In patients who have failed a trial of antiarrhythmic drugs, left atrial ablation has emerged as a highly successful alternative nonpharmacologic therapy. The technique is more successful in patients with PAF. Despite AF subtype, the approach is successful in the majority of patients. It is unclear when and if anticoagulation can be stopped, and a standardized approach is difficult to adapt to variable patient comorbidities and per- sistent asymptomatic episodes of AF. One study has shown that, in patients
Atrial flutter is characterized by which of the following:
It accounts for 10% of patients presenting with SVT
It is 2.5 times more common in men than women
Overall mortality is similar in comparison to patients with AF
Intra-atrial macroreentrant tachycardia involving a critical slow conduction zone
All of the above
Answers a to d are all associated with atrial flutter.
All of the following are contraindications for use of Ibutilide to chemically ter- minate atrial flutter with rapid ventricular rates except:
A prolonged QT interval
A history of polymorphic VT with class 1 or 3 antiarrhythmic drugs Severe hypokalemia
Hemodynamic instability
Structural heart disease
Patients with prolonged QT and a history of polymorphic VT with class I or III antiarrhythmic agents should not received ibutilide due to an increased risk of tor- sades de pointes. Likewise, significant hypokalemia can increase the risk of torsades de pointes. In patients with hemodynamic instability, emergency DC cardioversion is necessary. Patients with a structurally normal heart have a very low risk of torsades de pointes (1%) although lack of a normal heart in itself is not a contraindication (risk of torsades de pointes up to 4%).
All of the following are factors that are associated with atrial flutter except:
HTN
Valvular heart disease
Prior cardiac surgery
Pericardial disease
Sarcoidosis
Sarcoidosis is not a commonly recognized cause of atrial flutter. Answers a to d are all factors that predispose to atrial flutter. Other factors include dilated or HCM, CHF, sick sinus syndrome, thyrotoxicosis, chronic lung disease, and alcohol.
Which of the following summarizes the best approach for anticoagulation in a patient with persistent cavo-tricuspid isthmus dependent atrial flutter?
Aspirin 325 mg daily
Plavix75mgdaily
Warfarin therapy with a goal INR of 2.0 to 3.0 when risk factors for throm-
boembolic events are present
Aspirin81mgdailyandwarfarintherapywithagoalINRof2.0to3.0when
risk factors for thromboembolic events are present
Anticoagulation is not necessary in patients with flutters that originate from the
RA since they are not associated the a high risk of arterial thromboembolism
The risk of thromboembolism in patients with atrial flutter ranges from 1.7% to 7%. The guidelines for anticoagulation for patients with AF are extended to those with atrial flutter. For example, chronic warfarin therapy with a goal INR from 2.0 to 3.0 is recommended in those individuals with recurrent or persistent atrial flutter when risk factors for a thromboembolic event are present.
A clinical history of a gradual onset of palpitations that become more rapid over time favors which diagnosis?
AVNRT
AVRT
Atrial tachycardia
AF
Patients with automatic atrial tachycardia often report a gradual onset of symptoms that become more rapid (warm-up). In contrast, patients with AVNRT and AVRT tend to paroxysms of palpitations with an abrupt onset and offset.
A useful general approach for the assessment of a supraventricular arrhythmias includes all of the following except:
AVNRT: short RP tachycardia with P waves seen within or just after the QRS complex
AVRT: short RP tachycardia with P waves 110 msec or more after the QRS complex
Atrial tachycardia: long RP tachycardia
AVNRT: termination with a P wave
Atrial tachycardia: P-wave variation with subsequent beats during the tachycardia acceleration (warm up)
All of the answers are correct with the exception of e. In atrial tachycardia, the P wave morphologic features of the initial and subsequent beats are typically identical.
Which of the following situations can result in SVT with a wide QRS in the absence of a preexisting or rate-related bundle branch block?
Orthodromic AVRT
Antidromic AVRT
Atypical AVNRT
Typical AVNRT
In antidromic AVRT, antegrade conduction is through an accessory pathway, with retrograde conduction through the AV node (anti-against the normal AV node con- duction). An important exception to other forms of SVT is that a bystander accessory pathway, not involved in the tachycardia, may conduct to the ventricle and cause a pre-excited wide QRS.
All of the following are characteristics of atrial tachycardia except:
Long RP tachycardia associated with exertion Incessantatrialtachycardiaassociatedwithtachycardia-relatedcardiomyopathy May appear to be inappropriate sinus tachycardia
Valsalva-like maneuvers terminate the tachycardia
Valsalva-like maneuvers that terminate the tachycardia is a characteristic of AVNRT rather than atrial tachycardia.
Which of the following characteristics are associated with the permanent form of junction reciprocating tachycardia?
Mild tachycardia with rates from 100 to 130 bpm
Inverted P waves in II, III, AVF
Dilated cardiomyopathy
All of the above
None of the above
Answers a to c are all features that should prompt suspicion of the permanent form of junctional reciprocating tachycardia. The tachycardia is an AVRT utilizing a retro- grade posterior septal accessory pathway and is often incessant resulting in a tachy- cardia-mediated cardiomyopathy.
It is an acceptable approach to treat a tachycardia associated with QRS morpho- logic variation with an AV nodal blocking agent if there is proper hemodynamic monitoring. True or false?
a. True
b. False
False. QRS morphologic variation is an important clue to the presence of a pre-excited arrhythmia. With any pre-excited tachycardia, if AV node conduction is slowed, the degree of pre-excitation increases. With AV node slowing with blocking agents the ventricular response can paradoxically increase and predispose the patient to VF.
A 62-year-old female presents to the ED with a 2-hour history of severe chest pain, dyspnea, and diaphoresis. An initial ECG shows ST elevation in leads V2–V6. She proceeds immediately to coronary angiography where a 100% prox- imal LAD artery stenosis is discovered. The lesion is successfully opened with angioplasty followed by stent implantation, with resultant normal TIMI flow.
An echocardiogram shows a LV EF of 30% with regional wall motion abnor- malities along the anterior and lateral walls. In hospital telemetry reveals frequent PVCs and infrequent episodes on nonsustained VT (3–5 beats). What is the next step in her care?
Medical therapy and implantation of an ICD
Medical therapy and implantation of an ICD if VT is induced
Medical therapy and implantation of an ICD if a signal averaged ECG is
abnormal
Medical therapy and defer implantation of an ICD
Medical therapy and refer for radiofrequency ablation of the VT
The patient described had a large MI that was treated with percutaneous revascular- ization. PVCs and nonsustained VT are common. This type of patient was studied in DINAMIT. Although these patients are at relatively high risk of both sudden and total mortality, implantation of an ICD did not improve outcomes. If the patient has periods of sustained VT, an antiarrhythmic should be considered. Otherwise, medical therapy alone is appropriate, with follow-up assessment of her EF to determine if any functional recovery results from the revascularization.
A 14-year-old male presents for what is described as seizure-like activity with partic- ipation in athletics. The patient’s parents describe an episode that occurred while playing soccer in which he suddenly collapsed with what appeared to be tonic-clonic seizure activity and loss of urine. Outside of these discrete episodes the patient is oth- erwise healthy, takes no medications, and denies illicit drug use. There is no family history of arrhythmia, CV disease, or sudden death. What is the next step in his care?
Referral to a neurologist for an EEG
Empiric treatment with an antiepileptic medication
ECG and additional testing if necessary for long QT syndrome
Beta blockade and exercise restrictions
EP test
Exercise-induced seizures in this young patient require careful investigation for a car- diac tachyarrhythmia. Although such a patient may have a primary neurologic disor- der, the temporal correlation with activity is concerning for a primary cardiac disorder with a second neurologic manifestation. Long QT1 patients often present with exertion- related symptoms. The presence of long QT can be sought on the baseline ECG and, if needed, with exercise testing and an epinephrine challenge. Beta blockade and exercise restrictions are premature in this patient without a clear diagnosis, as HCM and other channelopathies may also cause a similar presentation. For this latter rea- son, although not offered as a choice in the question, an echocardiogram is appropri- ate to screen for structural heart disease.
A 62-year-old male presents with gradual onset fatigue, DOE, and lower extrem- ity edema. He also reports intermittent palpitations with presyncope that occur 1 to 2 times a month and last 2 to 4 minutes. He has a history of CAD and underwent three-vessel coronary artery bypass surgery 10 years ago.
His examination is remarkable for a JVP of approximately 10 mmHg, an S3 gallop and displaced apical impulse, crackles in the base of the lungs bilaterally, and 1
The patient may benefit from treatment with an ICD due to his ischemic heart disease and reduced LV EF. He is not a candidate based upon the MADIT I or II nor the ScD- HeFT due to his EF. The MUSTT examined patient with ischemic heart disease and a reduction LV EF (
The following statements in regard to inclusion criteria for the ICD trials are cor- rect except:
MADIT II: prior MI (
The MADIT II did not require evidence of decreased HR variability for study enrollment.
All of the following favor VT over paroxysmal SVT except:
AV dissociation
Fusion beats
Precordial nonconcordance
Lead V1 RBBB with larger left peak (Rsr’)
Lead V6 QRS with rS or S morphology
Precordial concordance is suggestive of VT. All the other answer choices are more consistent with SVT. In addition, clinical findings, such as a history of CAD, cannon a waves, and variable first heart sound on auscultation, favor VT.
Patients with repaired tetralogy of Fallot have frequent ventricular arrhythmias. All of the following are risk factors for VT except:
Number of years post operatively
RV failure
Pulmonary HTN
ASD resulting in RV overload
Answers a to c are all associated with the development of VT late after repair for tetralogy of Fallot. An ASD is not associated with risk of VT, although the presence of a significant residual shunt is associated with an increased risk of sudden death.
All of the following are congenital heart defects associated with an increased risk of an accessory pathway except:
Shone’s syndrome
Ebstein’s anomaly
Congenitally corrected transposition of the great vessels
Atrio-VSD
HCM
Shone’s syndrome, which is manifest by multiple LV outflow obstructions, is not asso- ciated with an increased risk of an accessory pathway. All of the other conditions con- vey an increased risk, in particular Ebstein’s anomaly.
Which of the following arrhythmias are associated with the likely congenital
abnormality of the patient in Question 102?
VT
Atrial flutter
Sinus node dysfunction
bandc
All of the above
In patients with an ostium secundum ASD, both atrial arrhythmias and late sinus node dysfunction are complications. In the absence of surgical repair, isthmus dependent atrial flutter is the most common atrial arrhythmia.
Which of the following is true in regard to patients with Ebstein’s anomaly of
the tricuspid valve?
Loss of a typical LBBB is suggestive of a right-sided pathway
Accessory pathway mediated tachycardia is the most common atrial
arrhythmia
Atrial flutter and fibrillation are common after the age of 35 years
Patients without a history of Wolff-Parkinson-White do not require a
preoperative EP study to assess for an accessory pathway
Atrial flutter and fibrillation are more common in patients more than 35 years of age. These two atrial arrhythmias combined exceed in prevalence accessory pathway mediated tachycardia in this age group. Loss of a typical right bundle branch block is suggestive of a right-sided pathway. Finally, patients with a history of palpitations or a documented tachycardia should undergo preoperative EP study, regardless of the presence or absence of pre-excitation on ECG.
All of the following are neurally mediated reflex syncopal syndromes except:
Vasovagal
Postmicturition
Gastrointestinal stimulation (swallow, defecation, visceral pain)
Carotid sinus
Parkinson disease with autonomic failure
Parkinson disease with autonomic failure typically results in orthostatic syncope. Answers a to d are all neurally mediated reflex syncopal syndromes. Others causes of neurally mediated reflex syncope include: acute hemorrhage, cough, sneeze, postexer- cise glossopharyngeal and trigeminal neuralgia, and a situational faint.
The following factors are associated with noncardiogenic syncope except:
Young age
Isolated syncope without underlying CV disease
Normal examination and ECG
Abrupt onset
Symptoms consistent with a vasovagal cause
An abrupt onset of syncope, particularly with exertion or while supine, is more consis- tent with a cardiogenic mechanism. All the other factors other than the correct answer d are more suggestive of a noncardiac mechanism. Factors suggestive of a cardiac mech- anism include: CAD, CHF, older age, abrupt onset, serious injuries, abnormal cardiac examination, structural heart disease, and an abnormal ECG (presence of a Q wave, bundle branch block, sinus bradycardia).
All of the following are class I indications for pacing except:
Symptomatic acquired complete (third degree) and advanced second degree AV block
Asymptomatic acquired complete (third degree) and advanced second degree AV block with asystole (
Patients with an acute inferior infarction can develop multiple types of electrical abnor- malities, including sinoatrial node dysfunction, first-degree AV block, second-degree block, and third-degree block at the level of the AV node. It is uncommon for any of these conduction disturbances to persist after resolution of the acute phase of the infarc- tion. These patients may require temporary pacing if hemodynamically unstable, but they rarely require permanent pacing. All the other answers are class I indications for pac- ing. Additional class I indications for pacing include: sinus node dysfunction with life- threatening, bradycardiac-dependent arrhythmias, recurrent syncope by carotid sinus stimulation with ventricular asystole of
Pacemaker syndrome is a hemodynamic abnormality that results from which of
the following abnormalities?
The delay between the right and LV pacing leads is too long to allow a syn- chronous contraction
Ventricular pacing is uncoupled from the atrial contraction
Cross talk that results in inappropriate inhibition of the pacing stimulus
Endless-loop tachycardia that results from retrograde P waves that trigger
another ventricular stimulation
Pacemaker syndrome results from inappropriate ventricular pacing or when the ven- tricular pacing is uncoupled from the atrial contraction. Patients may experience a variety of symptoms that include general malaise, a sensation of fullness in the head and neck, syncope, cough, dyspnea, heart failure, or weakness. They may have can- non A waves on exam and a lower BP when paced. The syndrome is most common when the VVI mode is used and the underlying rhythm is sinus.
Which of the following statements is incorrect regarding the intraoperative assessment of a pacing system?
Wire fracture: high voltage threshold, high-normal-low current threshold, high impedance
Insulation break: low voltage threshold, high current threshold, low lead impedance
Lead dislodgement: high voltage threshold, high current threshold, high lead impedance
Exit block: high voltage threshold, high current threshold, normal lead impedance
Lead dislodgement is typically characterized by a high voltage and current threshold, but normal lead impedance.
The following statements regarding CRT are true except:
It is a class IIa indication in patients with symptomatic medically refractory NYHA class III or IV failure with idiopathic or ischemic cardiomyopathy, prolonged QRS interval (
AF with rapid ventricular rates does not inhibit the use of CRT. The rapid ventricu- lar rates require careful management to allow the device to consistently pace both ven- tricles. If this is not medically feasible, then patients can undergo AV node ablation. The COMPANION trial showed a reduction in the primary endpoint of death and hospitalization for any causes with both CRT alone and when combined with an ICD. Multiple trials have demonstrated a benefit in 6-minute walk tests, NYHA functional class, quality of life, oxygen consumption, and functional MR.
