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IBHRE CCDS practice questions

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Question 1Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

During a routine pacemaker follow-up, the programmer printout shows a pacing spike followed by a wide QRS complex with a left bundle branch block morphology. Which pacing configuration most likely explains this finding?

  1. His bundle pacing with selective capture
  2. Biventricular pacing with LV-first timing
  3. Atrial pacing with intact AV conduction
  4. Right ventricular apical pacing Correct answer.

Explanation

Pacing from the right ventricular apex activates the ventricles outside the normal conduction system, producing a wide QRS with a left bundle branch block pattern and a superior axis. Biventricular and His bundle pacing tend to produce narrower complexes because they recruit more physiologic activation.

Question 2Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

A patient's pacemaker is programmed to VVI at 60 bpm. The underlying rhythm is sinus at 75 bpm with a PR interval of 0.24 s. What will the ECG most likely show?

  1. Native QRS complexes with no pacing output Correct answer.
  2. Pacing spikes that fall on the T wave
  3. A paced QRS after each P wave
  4. Pacing spikes before every QRS complex

Explanation

In VVI mode the device only paces the ventricle when the intrinsic ventricular rate falls below the programmed lower rate. Because the native ventricular rate of 75 bpm exceeds the 60 bpm lower rate, the pacemaker inhibits and no pacing occurs.

Question 3Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

Which programmable parameter directly determines the minimum interval the pacemaker allows between a sensed atrial event and a paced ventricular event?

  1. Atrioventricular delay Correct answer.
  2. Ventricular refractory period
  3. Upper tracking rate
  4. Post-ventricular atrial refractory period

Explanation

The AV delay sets the interval between a sensed or paced atrial event and the subsequent ventricular output. Shortening or lengthening it changes the timing of ventricular pacing relative to atrial activity.

Question 4Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

During implantation of a dual-chamber pacemaker, the operator notes that the atrial lead tip is positioned in the right atrial appendage. What is the main advantage of this location?

  1. It minimizes the risk of phrenic nerve stimulation
  2. It eliminates the need for a ventricular lead
  3. It allows direct pacing of the left atrium
  4. It provides the most stable position with good atrial sensing and pacing thresholds Correct answer.

Explanation

The right atrial appendage is the traditional site for atrial lead placement because its trabeculated anatomy provides stable fixation and reliable sensing and pacing characteristics. Other atrial sites may be used but often have less favorable acute parameters.

Question 5Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

Which of the following best describes the purpose of the post-ventricular atrial refractory period (PVARP) in a dual-chamber pacemaker?

  1. To determine the minimum ventricular pacing rate
  2. To limit the maximum ventricular pacing rate
  3. To set the amplitude of the atrial pacing output
  4. To prevent the pacemaker from tracking retrograde P waves or far-field signals after a ventricular event Correct answer.

Explanation

PVARP is a period after each ventricular event during which atrial signals are not used to trigger ventricular pacing. This prevents the device from tracking retrograde conduction or far-field R waves and avoids pacemaker-mediated tachycardia.

Question 6Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

A patient with a single-chamber ventricular pacemaker reports palpitations. The ECG shows a paced ventricular rhythm at 60 bpm with retrograde P waves visible after each paced QRS. What is the most appropriate initial programming change to address this?

  1. Decrease the ventricular output
  2. Shorten the AV delay
  3. Extend the ventricular refractory period Correct answer.
  4. Increase the ventricular pacing rate

Explanation

Retrograde P waves after a paced ventricular beat can be sensed by the device and, in a dual-chamber system, may trigger pacemaker-mediated tachycardia. Extending the ventricular refractory period or PVARP prevents sensing of these retrograde signals; in a single-chamber system, increasing the refractory period helps avoid sensing retrograde events.

Question 7Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

An ICD patient's device delivers a shock while the patient is awake and symptomatic. Interrogation shows the episode was classified as ventricular fibrillation. Which feature is designed to reduce inappropriate therapy for atrial fibrillation with rapid ventricular response?

  1. SVT discrimination criteria Correct answer.
  2. Lower rate limit
  3. Capture management
  4. Hysteresis

Explanation

Supraventricular tachycardia discrimination algorithms analyze rate, onset, stability, and AV relationship to distinguish atrial fibrillation or other SVTs from ventricular arrhythmias. This reduces inappropriate shocks for rapid supraventricular rhythms.

Question 8Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

A patient with a dual-chamber ICD has a ventricular lead with a defibrillation coil in the right ventricle and a superior vena cava coil. During defibrillation threshold testing, the shock fails to terminate VF. Which programming change is most likely to improve defibrillation success?

  1. Decreasing the shock energy
  2. Reversing the shock polarity Correct answer.
  3. Shortening the ventricular refractory period
  4. Increasing the lower rate limit

Explanation

Reversing shock polarity changes the current pathway and can improve defibrillation efficacy when the initial configuration fails. Other options such as optimizing lead position or adding a coil may also be considered, but polarity reversal is a standard first programming adjustment.

Question 9Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

Which of the following is the most common cause of an elevated pacing capture threshold noted at implantation?

  1. High atrial rate
  2. Lead tip positioned in fibrous tissue or poor myocardial contact Correct answer.
  3. Battery depletion
  4. Inappropriate mode switching

Explanation

Elevated capture thresholds at implant usually reflect poor lead-tissue contact, fibrosis, or positioning in scarred myocardium. Repositioning the lead to a site with healthy myocardium typically improves thresholds.

Question 10Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

A pacemaker patient is being evaluated for an MRI. The device is an older model without MRI conditional labeling. What is the most appropriate action?

  1. Perform a risk-benefit assessment and, if needed, follow institutional protocols for non-conditional devices Correct answer.
  2. Replace the device before any MRI is considered
  3. Disable all pacing outputs during the scan
  4. Proceed with the MRI without any precautions

Explanation

For non-MRI-conditional devices, the decision to scan requires a risk-benefit assessment and adherence to institutional protocols, which may include reprogramming and monitoring. Not all non-conditional devices are absolute contraindications.

Question 11Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

During a follow-up, the programmer shows a paced rhythm at 70 bpm with a consistent pacing spike followed by a QRS complex. The measured pacing impedance is 350 ohms. What does this impedance value most likely indicate?

  1. An acceptable lead impedance Correct answer.
  2. An insulation breach
  3. A loose set screw
  4. A lead fracture

Explanation

A pacing impedance in the range of roughly 300 to 1000 ohms is generally considered acceptable for modern leads. Values outside this range may suggest fracture, insulation failure, or connection problems.

Question 12Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

Which of the following best explains why the ventricular pacing rate may be lower than the programmed lower rate limit during hysteresis?

  1. The upper tracking rate is limiting output
  2. The device is malfunctioning
  3. The atrial lead is sensing noise
  4. The device allows the intrinsic rate to fall below the lower rate limit before pacing resumes Correct answer.

Explanation

Hysteresis permits the intrinsic rate to drop below the programmed lower rate before pacing starts, promoting native conduction. Once pacing begins, it continues at the lower rate limit.

Question 13Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

A patient with a dual-chamber pacemaker has a programmed mode of DDD with a lower rate of 60 bpm and an upper tracking rate of 120 bpm. The patient develops atrial flutter at 300 bpm. What is the most likely device response?

  1. Mode switch to a non-tracking mode such as DDIR or VDIR Correct answer.
  2. Asystole
  3. Atrial pacing at 300 bpm
  4. Ventricular pacing at 300 bpm

Explanation

Mode switching algorithms detect atrial tachyarrhythmias and switch to a non-tracking mode to prevent rapid ventricular pacing. This protects the patient from inappropriate high-rate ventricular pacing.

Question 14Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

Which of the following is a key advantage of bipolar pacing leads compared with unipolar leads?

  1. Lower pacing impedance
  2. Reduced susceptibility to far-field signal oversensing Correct answer.
  3. Greater risk of pectoral muscle stimulation
  4. Larger pacing artifacts on the surface ECG

Explanation

Bipolar leads have a smaller sensing dipole, which reduces oversensing of far-field signals such as pectoral muscle activity or distant cardiac signals. Unipolar leads have larger artifacts and greater susceptibility to interference.

Question 15Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

An ICD patient has a ventricular lead with a true bipolar sensing configuration. Which of the following is most likely to be sensed inappropriately by this lead?

  1. Diaphragmatic myopotentials
  2. Far-field R waves Correct answer.
  3. T waves
  4. Pectoral muscle activity

Explanation

True bipolar leads are less susceptible to myopotentials but can still oversense far-field R waves because the sensing dipole may include atrial tissue, particularly with a proximal ring electrode near the atrium. T-wave oversensing is also possible but is less specific to bipolar configuration.

Question 16Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

A patient with a biventricular pacemaker has a QRS duration of 160 ms with a left bundle branch block pattern. The device is programmed to LV-first pacing. What is the primary goal of this pacing configuration?

  1. To improve ventricular synchrony and cardiac output Correct answer.
  2. To prevent atrial fibrillation
  3. To increase the atrial rate
  4. To reduce the defibrillation threshold

Explanation

Biventricular pacing with LV-first timing is used in cardiac resynchronization therapy to restore synchronous ventricular activation and improve cardiac output in patients with wide QRS and LBBB. It does not directly affect atrial rate or defibrillation threshold.

Question 17Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

Which of the following is the most appropriate initial response to a pacemaker patient who reports dizziness and is found to have a pacing rate below the programmed lower rate limit on ECG?

  1. Schedule a routine follow-up in six months
  2. Increase the pacing output without interrogation
  3. Interrogate the device to assess battery status, lead integrity, and programmed parameters Correct answer.
  4. Reassure the patient that this is normal

Explanation

A rate below the lower rate limit may indicate battery depletion, lead failure, oversensing, or inappropriate programming. Device interrogation is the essential first step to identify the cause and guide correction.

Question 18Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

During implantation, the operator tests the atrial lead and finds a pacing threshold of 0.5 mA at 0.4 ms with a P-wave amplitude of 3.0 mV. How should these values be interpreted?

  1. Acceptable acute values for an atrial lead Correct answer.
  2. Unacceptable because the pacing threshold is too high
  3. Indicative of lead fracture
  4. Unacceptable because the P-wave amplitude is too low

Explanation

An acute atrial pacing threshold of 0.5 mA at 0.4 ms and a P-wave amplitude of 3.0 mV are generally acceptable. Typical acceptable P-wave amplitudes are above 1.5 to 2.0 mV, and thresholds below 1.0 mA are favorable.

Question 19Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

Which of the following best describes the purpose of a defibrillation threshold (DFT) test during ICD implantation?

  1. To determine the lower rate limit
  2. To assess atrial sensing
  3. To confirm that the device can reliably terminate ventricular fibrillation at the programmed energy Correct answer.
  4. To measure the pacing capture threshold

Explanation

DFT testing verifies that the ICD can detect and terminate ventricular fibrillation with an adequate safety margin. It helps confirm lead configuration and shock efficacy before the device is relied upon clinically.

Question 20Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

A patient with an ICD experiences an inappropriate shock during sleep. Interrogation reveals the device detected ventricular fibrillation, but stored electrograms show a sinus rhythm with a prominent T wave. What is the most likely cause?

  1. Atrial fibrillation
  2. Battery depletion
  3. Lead fracture
  4. T-wave oversensing Correct answer.

Explanation

T-wave oversensing occurs when the device misclassifies a large T wave as a ventricular signal, leading to double counting and inappropriate detection of ventricular fibrillation. Adjusting sensitivity or refractory periods can help prevent recurrence.

Question 21Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

A pacemaker patient with a unipolar ventricular lead develops pectoral muscle twitching during pacing. Which programming change is most likely to resolve this?

  1. Decrease the lower rate limit
  2. Shorten the AV delay
  3. Reprogram the lead to bipolar pacing Correct answer.
  4. Increase the pacing output

Explanation

Unipolar pacing uses a large current path between the lead tip and the device can, which can stimulate pectoral muscles. Reprogramming to bipolar pacing narrows the current path and reduces muscle stimulation.

Question 22Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

Which of the following is the most important reason to program a long ventricular refractory period after a sensed ventricular event in a dual-chamber pacemaker?

  1. To shorten the AV delay
  2. To reduce the pacing output
  3. To increase the maximum tracking rate
  4. To prevent sensing of the T wave and avoid inappropriate inhibition Correct answer.

Explanation

A long ventricular refractory period after a sensed event prevents the device from sensing the T wave as a separate ventricular signal. This avoids inappropriate inhibition or double counting.

Question 23Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

A patient with a dual-chamber ICD has an atrial lead with a pacing threshold of 2.5 mA at 0.4 ms and a P-wave amplitude of 0.8 mV at implant. What is the most appropriate action?

  1. Program a higher atrial output and lower sensitivity
  2. Reposition the atrial lead to a site with better sensing and pacing parameters Correct answer.
  3. Disable the atrial lead
  4. Accept the values and proceed with implantation

Explanation

A P-wave amplitude of 0.8 mV is below the usual acceptable minimum, and a threshold of 2.5 mA is relatively high. Repositioning the lead to a site with better tissue contact improves sensing and reduces the risk of undersensing or loss of capture.

Question 24Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

Which of the following best explains why the paced QRS complex is narrower with His bundle pacing than with right ventricular apical pacing?

  1. His bundle pacing uses a larger pacing output
  2. His bundle pacing activates the ventricles through the native conduction system Correct answer.
  3. His bundle pacing is always bipolar
  4. His bundle pacing avoids the atrial lead

Explanation

His bundle pacing captures the native His-Purkinje system, resulting in rapid and synchronized ventricular activation similar to normal conduction. Right ventricular apical pacing activates the myocardium slowly, producing a wide QRS.

Question 25Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

During a pacemaker follow-up, the programmer shows a paced rhythm at 60 bpm with a pacing spike followed by a QRS complex, but the spike-to-QRS interval is unusually long. Which parameter is most likely programmed too long?

  1. Ventricular refractory period
  2. Upper tracking rate
  3. AV delay Correct answer.
  4. PVARP

Explanation

The AV delay determines the interval between atrial and ventricular pacing. A long AV delay produces a long spike-to-QRS interval in dual-chamber pacing.

Question 26Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

A pacemaker is programmed to VVI at 60 bpm with a hysteresis rate of 50 bpm. The patient's intrinsic ventricular rate is 55 bpm. What pacing behavior should be expected?

  1. The device withholds pacing and lets the intrinsic 55 bpm rhythm continue Correct answer.
  2. The device paces at 55 bpm to match the intrinsic rate
  3. The device paces at 50 bpm to maintain the hysteresis rate
  4. The device paces at 60 bpm because the rate is below the lower rate limit

Explanation

Hysteresis allows the paced rate to fall to the hysteresis rate (50 bpm) as long as intrinsic activity persists above it, so intrinsic beats at 55 bpm are not inhibited by pacing. Pacing resumes only when the intrinsic rate drops below 50 bpm. This reduces unnecessary ventricular pacing.

Question 27Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

Which programmable parameter most directly determines the maximum rate at which a dual-chamber pacemaker will track sensed atrial activity?

  1. Maximum tracking rate Correct answer.
  2. Post-ventricular atrial refractory period
  3. Atrioventricular delay
  4. Ventricular refractory period

Explanation

The maximum tracking rate (MTR) sets the fastest ventricular paced rate the device will deliver in response to sensed atrial events. Atrial rates above the MTR result in Wenckebach-like behavior or mode switching depending on programming.

Question 28Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

A patient with a dual-chamber pacemaker develops a rapid paced rhythm at the maximum tracking rate with retrograde atrial activation. Which mechanism best explains this finding?

  1. Atrial undersensing
  2. Ventricular oversensing of T waves
  3. Loss of capture at the atrial lead
  4. Pacemaker-mediated tachycardia Correct answer.

Explanation

Pacemaker-mediated tachycardia occurs when a paced ventricular beat conducts retrogradely to the atrium, is sensed by the atrial lead, and is tracked back to the ventricle, creating a reentrant loop. Programming a longer PVARP or enabling specific algorithms prevents it.

Question 29Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

During ICD implantation, the defibrillation threshold is best described as which of the following?

  1. The energy required to pace the ventricle after a shock
  2. The energy at which the device first detects ventricular fibrillation
  3. The maximum energy the device can deliver
  4. The lowest shock energy that reliably terminates induced ventricular fibrillation Correct answer.

Explanation

The defibrillation threshold represents the minimum energy that consistently defibrillates the heart during induced arrhythmia testing. It guides programming of shock energy with an adequate safety margin.

Question 30Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

A patient with an ICD receives a shock during sleep. Interrogation shows the ventricular rate was 190 bpm with atrial fibrillation and a rapid ventricular response. Which programming change most directly reduces future inappropriate shocks in this situation?

  1. Shorten the ventricular refractory period
  2. Increase the ventricular pacing output
  3. Enable a supraventricular tachycardia discrimination algorithm Correct answer.
  4. Lower the lower rate limit

Explanation

Discrimination algorithms such as rate-onset, stability, and AV relationship criteria help the device distinguish supraventricular tachycardias from ventricular arrhythmias. This reduces shocks delivered for rapid atrial fibrillation.

Question 31Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

Which lead configuration is associated with a larger sensing signal but greater susceptibility to pectoral muscle interference?

  1. True bipolar
  2. Unipolar Correct answer.
  3. Integrated bipolar
  4. Dedicated bipolar

Explanation

Unipolar sensing uses the lead tip as the cathode and the device can as the anode, producing a larger antenna-like sensing field. This increases susceptibility to myopotential and electromagnetic interference compared with bipolar configurations.

Question 32Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

A patient with a single-chamber pacemaker set to VVI 70 bpm has an intrinsic ventricular rate of 40 bpm. What is the expected pacing behavior?

  1. The device paces at 70 bpm because the intrinsic rate is below the lower rate limit Correct answer.
  2. The device inhibits pacing because intrinsic activity is present
  3. The device paces at 40 bpm to match the intrinsic rate
  4. The device paces at 35 bpm due to hysteresis

Explanation

In VVI mode, the device paces the ventricle whenever the intrinsic rate falls below the programmed lower rate limit. With an intrinsic rate of 40 bpm and a lower rate limit of 70 bpm, pacing occurs at 70 bpm.

Question 33Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

A patient with a biventricular pacemaker for heart failure reports no improvement. Interrogation shows the left ventricular lead has a high capture threshold and intermittent loss of capture. Which action is most appropriate?

  1. Shorten the AV delay without other changes
  2. Reprogram the LV pacing configuration and consider lead revision Correct answer.
  3. Increase the atrial pacing output
  4. Disable the LV lead permanently

Explanation

Loss of LV capture undermines CRT benefit, so reprogramming the pacing configuration (e.g., changing the cathode/anode) or revising the lead is appropriate. Simply adjusting atrial output or AV delay does not address the failing LV lead.

Question 34Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

Which of the following is the most reliable indicator of adequate atrial lead sensing at implantation?

  1. A pacing threshold of 2.0 mA at 0.4 ms
  2. A P-wave amplitude of at least 1.5 to 2.0 mV Correct answer.
  3. A slew rate below 0.5 V/s
  4. A lead impedance of 300 ohms

Explanation

Adequate atrial sensing is reflected by a sufficiently large P-wave amplitude, typically at least 1.5 to 2.0 mV. Higher amplitudes improve the signal-to-noise ratio and reduce undersensing.

Question 35Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

A patient with a pacemaker set to DDD 60/120 has an intrinsic sinus rate of 130 bpm. What is the expected ventricular response?

  1. No ventricular pacing because intrinsic conduction is present
  2. Ventricular pacing at 120 bpm with Wenckebach behavior Correct answer.
  3. Ventricular pacing at 130 bpm tracking every P wave
  4. Ventricular pacing at 60 bpm due to mode switching

Explanation

When the atrial rate exceeds the maximum tracking rate, the device cannot track every P wave and exhibits Wenckebach-like behavior, pacing the ventricle at the maximum tracking rate with progressively lengthening AV intervals.

Question 36Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

Which of the following is the most common cause of a high pacing impedance at follow-up?

  1. Insulation breach
  2. High pacing output
  3. Lead fracture or conductor discontinuity Correct answer.
  4. Battery depletion

Explanation

A markedly elevated pacing impedance often indicates a conductor fracture or discontinuity that increases resistance in the circuit. Insulation breaches typically lower impedance by allowing current to leak into surrounding tissue.

Question 37Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

A patient with an ICD and a single-chamber ventricular lead has a ventricular fibrillation detection rate set at 200 bpm. The patient presents with syncope and interrogation shows a ventricular rate of 180 bpm that was not treated. Which factor best explains the lack of therapy?

  1. The rate was below the detection rate cutoff Correct answer.
  2. The lead had a normal sensing threshold
  3. The shock impedance was too high
  4. The device was in a monitoring-only mode

Explanation

Ventricular tachyarrhythmias are treated only when the sensed rate meets or exceeds the programmed detection rate. A rate of 180 bpm falls below the 200 bpm cutoff and would not trigger therapy in that zone.

Question 38Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

Which of the following best explains why oversensing of far-field R waves can occur on an atrial lead?

  1. The atrial lead is programmed to a unipolar configuration
  2. The atrial lead is positioned in the appendage
  3. The atrial lead can sense large ventricular signals when the ventricular amplitude is high Correct answer.
  4. The atrial lead has a lower impedance than the ventricular lead

Explanation

Far-field R-wave oversensing occurs when the atrial lead detects the ventricular depolarization, especially when the ventricular signal is large or the lead is positioned near the ventricle. This can cause inappropriate atrial tracking or mode switching.

Question 39Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

A patient with a dual-chamber pacemaker has a programmed AV delay of 200 ms. The intrinsic PR interval is 160 ms. What is the expected behavior?

  1. The device paces the ventricle at the end of the AV delay regardless of intrinsic conduction
  2. The device paces the atrium because the PR interval is shorter than the AV delay
  3. The device switches to VVI mode
  4. The device senses the intrinsic P wave and inhibits ventricular pacing if intrinsic conduction occurs before the AV delay expires Correct answer.

Explanation

In DDD mode, a sensed atrial event starts the AV delay. If intrinsic ventricular conduction occurs before the delay expires, the ventricular pacing output is inhibited. A shorter intrinsic PR interval than the programmed AV delay therefore results in intrinsic ventricular conduction.

Question 40Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

Which of the following is the most appropriate initial management for a pacemaker patient with pacemaker syndrome?

  1. Shorten the ventricular refractory period
  2. Reprogram to a mode that maintains AV synchrony, such as DDD Correct answer.
  3. Increase the lower rate limit in VVI mode
  4. Decrease the ventricular pacing output

Explanation

Pacemaker syndrome results from loss of AV synchrony, often during VVI pacing with retrograde conduction. Reprogramming to a dual-chamber mode that preserves AV synchrony, such as DDD, addresses the underlying mechanism.

Question 41Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

Which of the following best describes the function of the blanked period after a paced ventricular event?

  1. It measures the pacing threshold automatically
  2. It determines the maximum tracking rate
  3. It prevents the device from sensing the pacing artifact and evoked response Correct answer.
  4. It sets the atrial refractory period

Explanation

The blanking period is a brief interval during which the sensing amplifier is disabled to prevent the device from detecting its own pacing artifact. This avoids inappropriate inhibition or mode switching.

Question 42Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

A patient with an ICD has a ventricular lead with a true bipolar sensing configuration and a defibrillation coil in the superior vena cava. Which of the following is the most likely benefit of the true bipolar configuration?

  1. Larger shock vectors for defibrillation
  2. Lower defibrillation threshold
  3. Reduced susceptibility to far-field and myopotential oversensing Correct answer.
  4. Increased pacing capture threshold

Explanation

True bipolar sensing uses closely spaced electrodes, which narrows the sensing field and reduces oversensing of far-field signals and myopotentials. Shock delivery is determined by the high-voltage coil configuration, not the sensing configuration.

Question 43Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

A patient with a pacemaker has a programmed mode of AAI with a lower rate of 60 bpm. The patient develops complete heart block. Which of the following is the most serious consequence?

  1. Atrial undersensing
  2. Loss of atrial capture
  3. Ventricular asystole because the device cannot pace the ventricle Correct answer.
  4. Inappropriate mode switching

Explanation

AAI mode paces only the atrium and does not provide ventricular support. If complete heart block develops, the ventricle may not be paced, leading to asystole or severe bradycardia. This is why AAI is generally avoided in patients at risk for AV block.

Question 44Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

Which of the following is the most important reason to measure the slew rate when evaluating a sensed intracardiac signal?

  1. It indicates battery longevity
  2. It measures lead impedance
  3. It determines the pacing threshold
  4. It reflects how rapidly the signal changes and affects detection by the sensing amplifier Correct answer.

Explanation

The slew rate describes the rate of change of the intracardiac electrogram, which influences how well the device's sensing amplifier can detect the signal. Higher slew rates generally improve detection.

Question 45Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

A patient with a dual-chamber ICD has an atrial lead with a pacing threshold of 2.5 mA at 0.4 ms and a P-wave amplitude of 0.8 mV. Which of the following is the most appropriate interpretation?

  1. The atrial lead has acceptable parameters
  2. The atrial lead has a high pacing threshold and low sensing amplitude, suggesting lead repositioning Correct answer.
  3. The atrial lead has a low pacing threshold
  4. The atrial lead has an adequate P-wave amplitude

Explanation

A pacing threshold of 2.5 mA at 0.4 ms is higher than desirable, and a P-wave amplitude of 0.8 mV is lower than the typical target of at least 1.5 to 2.0 mV. Together these suggest suboptimal lead position and possible repositioning.

Question 46Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

Which of the following best explains why His bundle pacing can produce a narrower paced QRS complex than right ventricular apical pacing?

  1. It activates the conduction system, preserving more physiologic ventricular activation Correct answer.
  2. It uses a larger pacing output
  3. It shortens the AV delay
  4. It paces the atrium instead of the ventricle

Explanation

His bundle pacing captures the native conduction system, allowing rapid and synchronized activation of both ventricles and producing a narrower QRS. Right ventricular apical pacing activates the ventricle slowly outside the conduction system.

Question 47Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

A patient with a pacemaker reports hiccups synchronous with pacing. Which of the following is the most likely cause?

  1. Loss of atrial capture
  2. Atrial undersensing
  3. Battery depletion
  4. Diaphragmatic stimulation from a lead with high output or a perforation Correct answer.

Explanation

Hiccups synchronous with pacing suggest stimulation of the diaphragm, which can occur with high pacing output, a lead positioned near the phrenic nerve, or lead perforation. Evaluation of lead position and output is warranted.

Question 48Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

Which of the following is the most appropriate action when a pacemaker patient's device shows a sudden drop in lead impedance to very low values?

  1. Reprogram to a unipolar configuration
  2. Evaluate for an insulation breach and consider lead revision Correct answer.
  3. Increase pacing output
  4. Ignore the finding if pacing is adequate

Explanation

A sudden very low impedance suggests an insulation breach allowing current to leak into surrounding tissue. Evaluation for lead integrity and possible revision are appropriate to prevent loss of capture or inappropriate sensing.

Question 49Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

A patient with an ICD is being evaluated after a shock. Interrogation shows the episode was ventricular fibrillation and the shock was appropriate. Which of the following is the most appropriate next step?

  1. Document the episode and review device programming and medications Correct answer.
  2. Increase the detection rate to prevent future shocks
  3. Disable tachyarrhythmia therapy
  4. Replace the device immediately

Explanation

An appropriate shock for ventricular fibrillation indicates the device is functioning as intended. The next step is to document the episode, review programming, and assess the patient's clinical status and medications.

Question 50Cardiac rhythm device therapy (pacemakers and ICDs) - implantation and management knowledge base for allied professionals assisting physicians

Which of the following best describes the purpose of the ventricular safety pacing feature in a dual-chamber pacemaker?

  1. To deliver a pacing pulse at a short AV interval when a ventricular sensed event occurs within the crosstalk window Correct answer.
  2. To measure the ventricular pacing threshold
  3. To increase the ventricular pacing rate during exercise
  4. To prevent atrial oversensing

Explanation

Ventricular safety pacing delivers a ventricular pacing pulse at a shortened AV interval when a ventricular event is sensed within the crosstalk window, preventing inappropriate inhibition from crosstalk while avoiding a long pause.