B P7 C69 Pacemakers and Implantable Cardioverter-Defibrillators

Question 1

ICDs are indicated for prevention of sudden death from VT/VF, either as _____________________ in patients who have been resuscitated from VT/VF or ____________________ in patients who have not had VT/VF but are at sufficiently high risk to warrant protection with an ICD.

Answer 1

Secondary prevention

Primary prevention

Question 2

Evaluated implantable cardioverter–defibrillator vs antiarrhythmic drugs in patients who had been resuscitated from near-fatal ventricular fibrillation or who had undergone cardioversion from sustained ventricular tachycardia

One group of patients was treated with implantation of a cardioverter–defibrillator; the other received class III antiarrhythmic drugs, primarily amiodarone at empirically determined doses

Among survivors of ventricular fibrillation or sustained ventricular tachycardia causing severe symptoms, the implantable cardioverter–defibrillator is superior to antiarrhythmic drugs for increasing overall survival.

Answer 2

AVID trial (Antiarrhythmics versus Implantable Defibrillators (AVID) Trial)

Ito lang may benefit sa mortality/survival vs CIDS and CASH

Question 3

Prospective, multicenter, randomized comparison of implantable cardioverter-defibrillator (ICD) versus antiarrhythmic drug therapy in survivors of cardiac arrest secondary to documented ventricular arrhythmia

Patients were randomized to an ICD, amiodarone, propafenone, or metoprolol (ICD versus antiarrhythmic agents randomization ratio 1:3)

During long-term follow-up of cardiac arrest survivors, therapy with an ICD is associated with a 23% (nonsignificant) reduction of all-cause mortality rates when compared with treatment with amiodarone/metoprolol. The benefit of ICD therapy is more evident during the first 5 years after the index event.

Answer 3

CASH trial (Randomized Comparison of Antiarrhythmic Drug Therapy With Implantable Defibrillators in Patients Resuscitated From Cardiac Arrest - The Cardiac Arrest Study Hamburg (CASH)

Long term benefit ito. Kailangan mo magtrabaho matagal - para magka CASH

Question 4

A total of 659 patients with resuscitated VF or VT or with unmonitored syncope were randomly assigned to treatment with the ICD or with amiodarone.

A 20% relative risk reduction occurred in all-cause mortality and a 33% reduction occurred in arrhythmic mortality with ICD therapy compared with amiodarone; this reduction did not reach statistical significance.

Answer 4

CIDS trial (Canadian Implantable Defibrillator Study (CIDS)
A Randomized Trial of the Implantable Cardioverter Defibrillator Against Amiodarone)

Question 5

Clinical trials do not support ICD implantation in low-LVEF patients within _________ of myocardial infarction (MI) or _______ of surgical revascularization;

Answer 5

40 days

90 days

Question 6

Class 1 indications for primary prevention of SCD in patients with IHD

Answer 6

In patients with LVEF of 35% or less that is due to ischemic heart disease who are at least 40 days’ post-MI and at least 90 days postrevascularization, and with NYHA class II or III HF despite GDMT, an ICD is recommended if meaningful survival of greater than 1 year is expected

In patients with LVEF of 30% or less that is due to ischemic heart disease who are at least 40 days’ postMI and at least 90 days postrevascularization, and with NYHA class I HF despite GDMT, an ICD is recommended if meaningful survival of greater than 1 year is expected

In patients with NSVT due to prior MI, LVEF of 40% or less and inducible sustained VT or VF at electrophysiological study, an ICD is recommended if meaningful survival of greater than 1 year is expected

Question 7

Class 1 indications for secondary prevention of SCD in patients with IHD

Answer 7

In patients with ischemic heart disease, who either survive SCA due to VT/VF or experience hemodynamically unstable VT or stable sustained VT not due to reversible causes, an ICD is recommended if meaningful survival greater than 1 year is expected.

In patients with ischemic heart disease and unexplained syncope who have inducible sustained monomorphic VT on electrophysiological study, an ICD is recommended if meaningful survival of greater than 1 year is expected

Question 8

Give class 1 indications for ICD implantation among patients with NICM

Answer 8

Class 1 - SCA survivor/sustained VT (2ndary prevention)

Class 1 - NYHA II, III, LVEF </= 35% and an ICD candidate (1mary prevention)

Question 9

Electrical therapy for cardiac arrhythmias includes low-voltage (typically _____V) pacing stimuli (pulses) and high-voltage (typically _____ V) stimuli (shocks)

Answer 9

Low voltage: 1 to 5 V

Shock: 500 to 1400 V

Question 10

Pacemakers deliver _____ to treat bradycardia.

ICDs deliver _____ to defibrillate ventricular fibrillation (VF) or to cardiovert ventricular tachycardia (VT).

Answer 10

Pacing pulses

Shocks

Question 11

ICDs also have _____ pacing functions that can deliver pacing pulses to treat bradycardia, as well as _____ pacing functions that can deliver sequences of rapid pacing pulses to treat ventricular or atrial tachyarrhythmias

Answer 11

Antibradycardia

Antitachycardia

Question 12

Cardiac resynchronization therapy (CRT) pacemakers (CRT-P) or ICDs (CRT-D) also provide electrical therapy for heart failure in the form of pacing pulses that _____ the ventricular contraction sequence.

Answer 12

Resynchronize

Question 13

Transvenous system pulse generators are typically located subcutaneously in the _____, though in pediatric patients, some older larger devices, or devices with leads inserted via the femoral vein or epicardially, the pulse generator may be in the abdomen. Pacemaker pulse generators are _____ than ICD devices

Answer 13

Upper chest

Smaller

Question 14

Transvenous pacemaker leads are typically implanted with lead tips in the _____.

Epicardial leads may be tunneled to the devices

Answer 14

RV and RA

Question 15

ICDs are readily identified by the presence of _____ on the leads

Answer 15

Defibrillation coils

Question 16

For CRT, leads may be placed in a _____.

Answer 16

LV branch of the coronary sinus or on the LV epicardium.

Question 17

Subcutaneous ICDs are typically placed subcutaneously in the _____ with leads tunneled subcutaneously.

Leadless devices can also be visualized _____

Answer 17

SC ICD: left chest along the axillary line

Leadless device: Radiographically

Question 18

Conventional pacemaker components include a _____.The lead system consists of one to three leads that are connected to the pacemaker PG via the lead pin.

Answer 18

Pulse generator (PG) that contains the battery and circuitry and the lead system

Question 19

Conventional single-chamber systems have one lead that usually connect to the _____.

Dual-chamber systems usually have leads that connect to the right ventricle and RA

Answer 19

RV endocardium or in some cases to the right atrium (RA)

Question 20

Cardiac resynchronization devices have a third lead that is placed to pace the left ventricle (LV) via a lead in a branch of the _____.

Answer 20

Coronary sinus or implanted on the LV epicardial surface

Question 21

_____ pacemakers are also commercially available and include self-contained devices implanted via a catheter to the right ventricle

Answer 21

Leadless

Question 22

Modern cardiac pacemakers perform a number of functions, but their most critical two actions remain _____.

Answer 22

Pacing and Sensing

Pacing means delivering a small (compared with a defibrillation shock) electrical stimulus of “1 to 5 V that captures a small myocardial region adjacent to the pacing electrode yielding a propagating wavefront in the chambers of interest (i.e.,the atria or ventricles)

Question 23

Pacing thresholds frequently vary over time early after implantation. For active fixation leads, transient myocardial injury elicited by securing them produces an elevated threshold for _____.

Answer 23

Minutes to hours

Question 24

Inflammation at the electrode tissue interface leads to a subacute threshold rise resolving in about ____ weeks.

Answer 24

6 weeks

Question 25

Drugs, electrolyte perturbations, and metabolic changes also affect pacing thresholds. _____ can elevate thresholds. Some studies, but not all, have found that _____ may elevate the pacing threshold as well. _____ may also result in loss of capture.

Answer 25

Elevate threshold: Severe hyperkalemia Significant hyperglycemia Severe hypothyroidism Acidosis or alkalosis Sodium channel blocking drugs (flecainide, propafenone, and others, as well as amiodarone Loss of capture: Acute ischemia and chronic infarction

Question 26

Effects on Pacing threshold

Answer 26

* Higher threshold Class 1C drugs (e.g., flecainide) Amiodarone (chronic effect, especially atrial thresholds) * Lower pacing threshold Glucocorticoids Isoproterenol and epinephrine

Question 27

Effects on Pacing burden

Answer 27

Increased atrial pacing burden: * Drugs that cause sinus bradycardia (e.g., beta blockers, amiodarone, lithium) Increased ventricular pacing burden: * Drugs that slow AV conduction (e.g., beta blockers, amiodarone)

Question 28

Frequency of VT or VF

Answer 28

* Increased Antiarrhythmic drugs Drugs with proarrhythmic side effects Drugs that interact with proarrhythmic drugs * Decreased Beta blockers Antiarrhythmic drugs (e.g., sotalol, amiodarone)

Question 29

ICD: Therapy for VT or VF Defibrillation energy requirement increase vs increase

Answer 29

Defibrillation energy requirement: Increase (class IB, class IC, chronic amiodarone, verapamil) Decrease (sotalol, dofetilide)

Question 30

Apart from pacemakers functioning in the asynchronous modes (_____), pacemakers need to accurately detect underlying atrial and/or ventricular native signals in order to know whether to and when to deliver a pacing stimulus

Answer 30

VOO, DOO

Question 31

NASPE/BPEG Generic Code for Bradycardia Pacing

Answer 31

I Chamber Paced II Chamber Sensed III Response to Sensing IV Rate Modulation

Question 32

Severe bradycardia and/or complete heart block with a junctional or ventricular escape adversely affects cardiac output. Instituting ventricular pacing at normal rates dramatically improves cardiac output by _____%. Restoring AV synchrony augments cardiac output still more by about ___%

Answer 32

25-30% +20%

Question 33

Nevertheless, there are additional advantages of maintaining the AV relationship. When patients were randomized to different rate responsive modes, most preferred a mode that maintained AV synchrony (i.e., _____ rather than VVIR)

Answer 33

DDDR

Question 34

Moreover, pacemaker syndrome occurs in 3% to 30% of patients who have ongoing sinus activity (i.e., not atrial fibrillation) when subjected to ventricular pacing. Its manifestations include ______

Answer 34

Datigue, dyspnea, dizziness, neck pulsations, chest pain, and hypotension

Question 35

Pacemaker syndrome is most common when a fixed VA relationship is present, wherein the _____. Dual-chamber as compared with single-chamber pacing leads to ______ occurrence of atrial fibrillation and of stroke and better quality of life in follow-up.

Answer 35

Atrial contractions encounter closed AV valves Reduced

Question 36

For dual-chamber pacing the AV interval is of importance. Pacemaker syndrome can occur with a _____ PR interval analogously to the problem with VA conduction alluded to above. On the other hand, too short of an AV interval or a marked interatrial conduction delay adversely affects performance. A hemodynamically optimal AV interval is typically about 150 msec at rest and somewhat less with exertion.

Answer 36

Severely prolonged PR interval

Question 37

The potential deleterious effects of RV pacing were initially obscured by the advantages of _____. Although slightly reduced LV function occurs acutely, even in patients with normal ventricular function, RV pacing rarely exhibits clinically obvious adverse effects in the short term in such patients. Elegant studies of direct His bundle stimulation clearly identified that both the contribution of atrial systole (by varying PR interval) and ventricular activation sequence (by comparing atrial- His bundle with atrial-RV) influenced ventricular function.

Answer 37

(1) Any pacing over severe bradycardia (2) AV sequential pacing over ventricular-only pacing (3) Rate-responsive pacing over fixed-rate pacing.

Question 38

The ameliorative role of biventricular pacing (CRT) in treating LBBB-related ventricular dysfunction cemented this observation since conduction with LBBB resembles RV apical pacing. Studies comparing ventricular pacing to native ventricular activation, especially in those with LV systolic dysfunction, demonstrated significantly increased heart failure events. The magnitude of the detriment with RV pacing worsened with ____.

Answer 38

Greater QRS prolongation Worse baseline LV function

Question 39

____ is the simplest mode. From the first through third letter, respectively, the mode paces only in the ventricle, does not sense the atrium or ventricle (O),and behaves asynchronously (O).There is one timing clock, the ventricular escape interval. For example, for VOO 60 bpm, the ventricular escape interval is 1000 msec (60,000 msec/min/ 60/min = 1000 msec). Thus every 1000 msec the pacemaker delivers a ventricular pacing pulse (even if a native ventricular beat has occurred).

Answer 39

VOO

Question 40

___ implies pacing in the ventricle (V) and sensing in the ventricle (V), and if a sensed event occurs, the next scheduled pacing pulse is inhibited (I).The sensed event resets the ventricular escape interval.This mode adds a ventricular refractory period, during which sensed events are ignored.This prevents double counting ventricular events or local T waves and falsely inhibiting pacing.

Answer 40

VVI

Question 41

In most pacemakers, applying a magnet converts the function from VVI to ____. Depending upon the manufacturer, model, and programming magnet application may also change the pacing rate and/or initiate other temporary behavior (e.g., performing a pacing threshold test).

Answer 41

VOO The VOO mode is useful when oversensing is present as in a lead fracture or is anticipated due to electrocautery or other electromagnetic interference (EMI).

Question 42

With respect to single chamber atrial pacing, ___ is analogous to VOO and AAI resembles VVI. In AAI, the device paces only in the atrium and senses in the atrium. In response to a sensed event, the next scheduled pacing pulse is inhibited, resetting the atrial escape interval.This mode, like VVI, has a refractory period, the atrial refractory period, during which sensed events are ignored. This prevents double counting atrial signals, or inappropriate sensing of far-field ventricular events that would falsely inhibit pacing.This mode is infrequently used due to the absence of ventricular support in the event of AV block.

Answer 42

AOO

Question 43

Dual-chamber modes more than double the complexity. In ___, the most commonly used one, pacing as well as sensing may occur in both the atrium and ventricle, as is evident from the first two letters.The third letter indicates that both inhibition and triggered events occur depending upon the circumstances. DDD preserves AV synchrony where possible. Unlike VVI or AAI there is an upper rate limit in addition to a lower rate limit.The occurrence of pacing versus native activity in the atrium and in the ventricle depends on the programmed rate and AV interval compared with the native sinus rate and AV conduction characteristics.Timing can be based on either the atrium or the ventricle.The AV interval may be different for sensed atrial versus paced atrial events and may shorten with faster rates.

Answer 43

DDD

Question 44

The ventricular sensed or paced event initiates an atrial refractory period, the _____ (PVARP). PVARP seeks to prevent the atrial channel from sensing either the far-field ventricular event or retrograde atrial events initiated by the ventricular event or atrial tachyarrhythmias. As inVVI,a ventricular refractory period is present as well to prevent double counting.

Answer 44

Postventricular atrial refractory period

Question 45

An atrial paced atrial event initiates a post-atrial ventricular blanking period to minimize the chance of the ventricular channel sensing the atrial pacing spike, also called _____, and inappropriately inhibiting resulting in ventricular asystole in the setting of complete AV block.

Answer 45

Crosstalk

Question 46

The DDI mode is used much less often. Unlike DDD, it does not exhibit atrial tracking. Thus, it can be useful in the setting of atrial oversensing to avoid _____. Another use of DDI is when there is intermittent atrial fibrillation but suboptimal atrial sensing prevents mode switching (in DDD); tracking of the AF is avoided in DDI. Operationally, in DDI, if the sinus rate is below the lower rate limit (LRL) the device will atrial pace at the LRL and then either native ventricular conduction will occur or the device will pace the ventricle at the conclusion of the AV delay. If the sinus rate is above the LRL the device will inhibit in the atrium; if AV conduction is absent it will pace the ventricle at the LRL (at a different rate than the atrium is firing, thus losing AV synchrony).

Answer 46

Inappropriate ventricular pacing

Question 47

The VDD mode is adequate for patients with intact _____. However, should sinus bradycardia below the LRL develop, the device will pace the ventricle (only, as the initial letter implies) at the LRL losing AV synchrony.

Answer 47

Sinus node function but with AV block

Question 48

Randomized trials have established that dual-chamber pacing is superior in reducing the occurrence of atrial fibrillation and possibly stroke, though a reduction in mortality has not been proven. Consequently a dual-chamber device is favored except when _____ is present

Answer 48

Permanent atrial fibrillation

Question 49

The recent availability of single chamber (ventricular) leadless pacemakers has led to a greater usage of these single chamber systems in some patients who would traditionally receive a dual-chamber device. Optimal leadless pacemaker candidates include those with _____.

Answer 49

(1) Increased infection risk (2) With limited vascular access (3) Who are expected to have a low (ventricular) pacing burden (4) Patients with minimal benefit from dual-chamber pacing due to advanced comorbidities or reduced activity

Question 50

Especially in the acute period after implantation, pacing lead dislodgement or elevation of threshold (to a value greater than the programmed value) will cause _____. Threshold elevation sometimes is mitigated by device-automated threshold determination and programmed output alteration. Lead fracture or other failure can cause loss of capture.Lead connection issues at the generator’s header are also important to consider.Pathologic capture failure must be distinguished from physiologic capture failure that occurs when a pacing impulse falls in the refractory period, sometimes due to undersensing.

Answer 50

Failure to capture

Question 51

The flipside of failure to capture is _____. Either can result in ventricular asystole. Failure to pace usually stems from ______. Advanced battery depletion or catastrophic device failure can cause loss of output,too.A special case of failure to pace,called cross- talk, is only possible in dual-chamber devices

Answer 51

Failure to pace Oversensing Either of physiologic signals (P,R,or T waves) of noncardiac or external noise (EMI), of lead fracture, or from a loose header connection

Question 52

Causes of Failure to Capture

Answer 52

Pacing output below threshold Changes at electrode-myocardial interface Output programmed below threshold Lead dislodgement Lead insulation failure or conductor fracture Connection problem between header and lead Functional failure to capture (undersensing or asynchronous pacing)

Question 53

Causes of Failure to Pace

Answer 53

Corrected by magnet or programming to asynchronous mode Oversensing of physiologic or nonphysiologic signals Not corrected by magnet or programming to asynchronous mode Failure in the pulse generator Lead conductor fracture Connection problem between header and lead

Question 54

Causes of Pacing at a rate not consistent with programmed rate

Answer 54

Shorter-than-expected escape interval: undersensing Longer-than-expected escape interval: oversensing Battery depletion

Question 55

Causes of unanticipated rapid pacing

Answer 55

Pacemaker-mediated tachycardia Inappropriate ventricular tracking of rapid sensed atrial rates, electromagnetic interference, or myopotentials Sensor-driven pacing unrelated to patient activity

Question 56

Common causes of ventricular pacing at URL in DDD mode

Answer 56

Pacemaker-mediated tachycardia Ventricular tracking of rapid atrial signals - Atrial tachyarrhythmias - Rapid oversensed signals (e.g., electromagnetic interference, lead- or connection-related oversensing)

Question 57

Pacemaker-mediated tachycardia (PMT), or _____, originates with a ventricular impulse (especially a PVC) that conducts retrogradely to the atrium, where it is sensed and thus triggers a paced ventricular beat at the expiration of the AV delay. Subsequently, that ventricular-paced beat may again conduct retrogradely to the atrium and the “reentrant loop” continues.The ECG shows ventricular pacing at or near the upper rate limit, and retrograde P waves. PMT can be prevented by programming the PVARP to an interval longer than the observed VA conduction interval; in addition, PVARP extension can be programmed to occur for PVCs. Once begun, PMT termination algorithms function by omitting tracking for one atrial event. Applying a magnet will terminate it as well. PMT will not occur in the DDI mode since it is dependent upon atrial tracking, but it can occur in VDD, as well as DDD.

Answer 57

Endless loop tachycardia

Question 58

_____, similar to PMT, also starts most commonly with a PVC that conducts retrogradely. However, due to timing and programming particulars, it falls in the PVARP.Atrial pacing then occurs at the LRL (or at the sensor indi- cated rate). However, in this scenario the atrial pacing pulse does not capture due to functional refractoriness from the preceding retrograde atrial activation. The sequence then repeats. It can be prevented by shortening the AV delay, reducing the PVARP and/or by reducing the lower rate, such as by inactivating rate-response pacing.

Answer 58

Non-reentrant ventricular-atrial synchrony

Question 59

Pacing-induced proarrhythmia includes several subtypes. The simplest form is an _____ ventricular pacing in the VOO mode triggering VT or VF. Any form of ventricular or atrial undersensing may allow pacing to trigger an arrhythmia. Even ventricular escape pacing at a low rate can rarely trigger ventricular tachyarrhythmias. A pause in pacing due to loss of capture during a threshold test or an RV pacing- minimization algorithm can initiate VT or VF by a short-long-short sequence. A pacing lead may mechanically trigger ectopic impulses, too.Competitive atrial pacing can trigger atrial tachyarrhythmias. Some manufacturers enable programming of a noncompetitive atrial pacing interval to minimize such events.

Answer 59

R-on-T

Question 60

ICDs are indicated for prevention of sudden death from VT/VF, either as _____.

Answer 60

Secondary prevention: patients who have been resuscitated from VT/VF Primary prevention: patients who have not had VT/VF but are at sufficiently high risk to warrant protection with an ICD.

Question 61

ICDs are the treatment of choice for secondary prevention of VT/VF, providing patients remain at risk for recurrence of VT/VF and have _____.

Answer 61

Sufficient life expectancy and quality of life to justify implantation.

Question 62

The largest trial, _____, randomized 1016 patients who were resuscitated from near-fatal VF, sustained VT with syncope, or sustained VT with left ventricular ejection fraction (LVEF) of >40% and symptoms suggesting severe hemodynamic compromise due to an arrhythmia to ICD implantation or antiarrhythmic drugs (mostly amiodarone). Overall survival was significantly greater in the ICD group (p < 0.02).

Answer 62

Antiarrhythmics Versus Implantable Defibrillators (AVID)

Question 63

The 2017 AHA/ACC/HRS Guideline for Management of Patients with Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death recommends ICD implantation in patients who survive sudden cardiac arrest due to VT/VF, hemodynamically unstable VT, stable sustained VT not due to reversible causes, or unexplained syncope with inducible sustained VT on electrophysiologic study, if meaningful survival greater than ____ year is expected (Class I recommendation).

Answer 63

> 1 year

Question 64

The _____ trial of patients with ischemic cardiomyopathy and LVEF of 30% or less demonstrated significant survival benefit of an ICD with survival benefit evident through 8 years of follow-up.

Answer 64

MADIT II

Question 65

The _____ trial of patients with LVEF of 35% or less and ischemic or nonischemic cardiomyopathy with NYHA functional Class II or III heart failure found that ICDs reduced total mortality.

Answer 65

SCD-HeFT

Question 66

_____ randomized patients with CAD and LVEF 40% or less with asymptomatic nonsustained VT to electrophysiology-guided therapy with antiarrhythmic drugs or ICD implantation versus no antiarrhythmic treatment; patients who received an ICD experienced reduced mortality

Answer 66

MUSTT

Question 67

A subsequent randomized controlled trial of patients with nonischemic cardiomyopathy and LVEF of 35% or less (_____ trial) found that ICDs did not reduce total mortality in patients who received guideline-directed medical therapy (GDMT) and indicated CRT pacemakers, though sudden cardiac death mortality was reduced.

Answer 67

DANISH

Question 68

Clinical trials do not support ICD implantation in low-LVEF patients within ___ days of myocardial infarction (MI) or 90 days of surgical revascularization

Answer 68

MI: 40 days Surgical revascularization: 90 days

Question 69

Candidates for a subcutaneous ICD undergo screening using surface ECG electrodes to assess the risk of _____; 7% to 10% of candidates fail screening. Despite this, inappropriate shocks caused by oversensing are more common in subcutaneous ICDs than in modern transvenous ICDs (5% to 10% versus <2% in the first year)

Answer 69

T wave oversensing or R wave double-counting

Question 70

Subcutaneous ICDs cannot perform _____

Answer 70

ATP, resynchronization, or long-term bradycardia pacing

Question 71

Advantages of subcutaneous ICD

Answer 71

Eliminates need for vascular, intravascular lead, and related complications (e.g., pneumothorax) No intravascular system infection Implant possible without fluoroscopy Lead failure may be less likely Relative simplicity and safety of lead extraction

Question 72

Advantages of transvenous ICD

Answer 72

Bradycardia, antitachycardia, and cardiac resynchronization pacing No preimplant ECG screening necessary Fewer inappropriate and avoidable shocks Greater battery longevity Shorter charge time; faster shock delivery Smaller pulse generator Long-term follow-up data

Question 73

Patient selection for subcutaneous ICD

Answer 73

Limited vascular access (e.g., dialysis) History or high risk of intravascular infection (e.g., prosthetic valve) Intracardiac shunt Young patient (ease of lead extraction and possible greater lead longevity)

Question 74

Patient selection for transvenous ICD

Answer 74

Need bradycardia, antitachycardia, or cardiac resynchronization pacing Fail subcutaneous ICD ECG screening

Question 75

Inappropriate shocks are painful, may lead to _____.

Answer 75

Myocardial injury and hemodynamic effects Impair patient quality of life Increase health care costs When repetitive they may engender a posttraumatic distress syndrome

Question 76

Modern ICDs terminate ventricular arrhythmias by _____. Except for VF, ATP is often used first, and if unsuccessful shocks are applied (up to five to eight before therapy is ceased). ATP is used preferentially because of the adverse effects of shocks discussed above

Answer 76

ATP and/or by one or more shocks

Question 77

Identify strategic programming principles for shock reduction Do not treat self-terminating VT. AF with rapid ventricular rate is less likely to exceed the rate threshold for a longer detection time.

Answer 77

Sufficiently long detection time

Question 78

Identify strategic programming principles for shock reduction Do not treat slower tachycardias, which are more likely to be SVT.

Answer 78

Fast VT detection rate in primary prevention patients and secondary-prevention survivors of VF

Question 79

Identify strategic programming principles for shock reduction Do not treat SVT.

Answer 79

SVT-VT discrimination

Question 80

Identify strategic programming principles for shock reduction ATP is painless. Even in the “VF” zone, most rhythms are monomorphic VT; many can be terminated by ATP.

Answer 80

ATP in all VT/VF detection zones

Question 81

Identify strategic programming principles for shock reduction Minimize unsuccessful shocks for VT, VF, or AF with rapid ventricular rate.

Answer 81

Maximum shock strength

Question 82

Identify strategic programming principles for shock reduction Minimize shocks for oversensing.

Answer 82

Enhanced sensing features

Question 83

Three-step approach to the patient who presents with a shock

Answer 83

First, analyze stored EGMs to determine if it was delivered in response to a tachycardia or oversensing. Second, if the shock responded to a tachycardia, determine if the rhythm is VT or SVT using established principles of ECG and EGM analysis. Third, determine whether an appropriate shock for VT/VF could have been avoided by either strategic program- ming or nondevice interventions

Question 84

The approach to shocks delivered for oversensing is guided by the _____. T wave oversensing was once a common cause of inappropriate shocks in transvenous ICDs, but its frequency has been reduced by multiple sensing enhancements and programming options. However, in subcutaneous ICDs, despite electrocardiographic prescreening, it remains the most common cause of oversensing, although a new filtering algorithm has reduced these events

Answer 84

Cause of oversensing

Question 85

A patient with a single shock can be evaluated in person or by remote monitoring within _____ hours. In contrast, repetitive shocks constitute an _____. The cause must be determined, and VT/VF detection may be disabled using a programmer or magnet. Repetitive shocks for VT/VF may be caused by multiple unsuccessful shocks for a single episode or recurrent VT/VF after successful shock termination (“VT storm”)

Answer 85

24-48 hours: Single shock Emergency: Repetitive shocks

Question 86

Pace-sense malfunctions account for most ICD lead failures. _____ is the most common initial electrical abnormality with either conductor fracture or insulation breach. Conductor fractures usually cause a characteristic pattern of oversensing. Unlike conductor fractures, insulation breaches themselves do not generate abnormal signals

Answer 86

Oversensing

Question 87

The chest x-ray film is unrevealing in most cases of lead failure, but it should be inspected for lead conductor discontinuity, kinks, or acute angles that identify stress points and twisting that suggests “_____.” It is important for excluding alternative causes of oversensing, such as lead dislodgement, abandoned leads, or lead fragments that cause a lead-lead interaction, and incomplete insertion of DF-1 pins into the header

Answer 87

Twiddler’s syndrome

Question 88

Common vascular access complications for transvenous devices include _____. Pneumothorax occurs in about 1% of implants, is avoidable with the cephalic vein access approach, is minimized with the extrathoracic approach, is diagnosed with chest x-ray, and if large or symptomatic, is treated with a chest tube

Answer 88

Pneumothorax, hemothorax, pocket hematoma, and more rarely inadvertent arterial access

Question 89

Inadvertent placement of the lead via the _____ into the left cardiac chambers can lead to stroke. The lateral view on a post-implant chest x-ray is vital to exclude this complication.

Answer 89

Subclavian vein or via a patent foramen ovale (PFO)

Question 90

Acute or subacute _____ may lead to ipsilateral upper extremity swelling; it should be managed with eleva- tion and anticoagulation.

Answer 90

Subclavian vein thrombosis

Question 91

Important complications related to lead placement include _____

Answer 91

Cardiac perforation Dislodgement Extracardiac stimulation Lead terminal pin to header connection problems

Question 92

Inadvertent nonmyocardial stimulation can include the _____.

Answer 92

(1) Right phrenic nerve from a lateral RA lead (2) Left phrenic nerve from an LV lead (3) Diaphragm itself directly from an RV lead (usually perforated but rarely at high output without perforation) (4) Chest wall including intercostal muscles from possible perforation

Question 93

Device infections include _____.

Answer 93

Pocket infections and/or systemic pre- sentations (including bacteremia, lead-associated endocarditis, and valvular endocarditis).

Question 94

Infections may present from days to years after implant. _____ are the most common pathogens. Immediate preoperative antibiotics are considered mandatory as they have been shown to reduce infections. Pocket hematomas and repeat operation (such as for hematoma or other complication) markedly increase the risk of infection.

Answer 94

Coagulase positive or negative staphylococci

Question 95

Leadless pacemaker implantation is not associated with pocket complications or pneumothorax, but can result in _____. Initial studies found a higher rate of pericardial complications with leadless (1.0% to 1.5%) than transvenous pacemakers, but one study has shown a decline in such events possibly due to increased operator experience

Answer 95

Femoral access-related complications or cardiac perforation

Question 96

In leadless pacemaker complications, tricuspid valve injury or regurgitation can occur especially for _____. Device dislodgement and embolization has occurred in 0% to 1.1% of implants. Pocket infection is of course eliminated, and intravascular infection appears to be much less likely even in cases of documented bacteremia, but one case has been reported.

Answer 96

More basal insertions or from device removal.

Question 97

Typical in-person follow-up intervals for patients on remote monitoring are yearly for pacemakers and ICDs. More frequent in-person follow-up is advisable for patients not on remote monitoring (e.g., every ____ months) or those who are pacemaker-dependent (e.g., every ____ months). In-person follow-up remains necessary for reprogramming or evaluation of suspected malfunction.

Answer 97

Not on remote monitoring: 3-6 mo Pacemaker dependent: 6 mo

Question 98

Ubiquitous electromagnetic waves sometimes interfere with CIEDs, potentially causing _____.

Answer 98

Temporary or permanent inactivation Inappropriate pacing or inhibition of pacing or shocks Inappropriate detection of VT/VF

Question 99

Medical sources of EMI are most frequently associated with _____.

Answer 99

Electrosurgery (electrocautery) or MRI

Question 100

A consensus statement requires preoperative determination of pacemaker dependency, device model, type of lead, and plans to use electrocautery to inform management. The arterial pulse must be monitored intraoperatively. Intraoperative management strategies may include_____. When a magnet is placed over a pacemaker, it paces _____. In contrast, a magnet placed over an ICD disables _____ but does not alter pacing mode.

Answer 100

Magnet application or perioperative reprogramming Pacemaker: Asynchronous ICD: disables detection of VT/VF

Question 101

If the surgical incision and dispersive ground pad are both _____, the risk of EMI is low. Rate-adaptive sensors should be disabled.

Answer 101

Below the umbilicus

Question 102

When external cardioversion is required, defibrillation pads should be placed at least _____ from the PG.

Answer 102

8 inches (20 cm) from the PG

Question 103

Improvements in battery longevity have led to devices that can last _____ years or longer, depending on pacing use, shocks, and threshold requirements.

Answer 103

> 10 years

Question 104

Pacemaker patients are not restricted from driving after the perioperative period. Guidelines for ICD patients recommend that patients refrain from driving for ___ months after each shock for VT/VF and for 6 months after ICD implant for secondary prevention.Primary prevention patients are not restricted from driving personal cars (versus commercial vehicles).

Answer 104

Shocl for VT/VF: 6 mo ICD implant for secondary prevention: 6 mo Primary prevention ICD: not restricted

Question 105

_____ improves health and quality of life but may induce VT/VF in patients with specific diseases. Decisions regarding sports participation should be based on the patient’s underlying disease, indication for ICD therapy (e.g.,primary versus secondary prevention,risk of exercise- induced VT/VF), and risks of specific sports (e.g., ICD system damage in contact sports, risk of trauma with transient loss of consciousness). Athletes with ICDs experience shocks for both VT/VF and SVT more frequently during sports than at rest, but the risk of injury or failure to terminate VT/VF is low. Swimming presents the risk of drowning even if VT/VF is treated promptly.

Answer 105

Exercise

Question 106

Beta blockers and other drugs that ____ AV conduction may increase RV pacing burden and thereby exacerbate HF.

Answer 106

Prolong AV conduction

Question 107

Antiarrhythmic drugs prescribed for VT/VF or AF (e.g., amiodarone) may _____ and thus require decreasing the rate threshold to ensure that VT is detected.

Answer 107

Slow the rate of VT