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Pacemaker Malfunctions

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Abstract

Pacemaker malfunction can present in several ways including failure of output, pacing failure, undersensing, oversensing, pacing at a slower or faster rate than the preset rate, pacemaker-mediated tachycardia, pacemaker syndrome, cross talk, or displacement of lead. Analysis of surface electrocardiogram is very useful in the identification and differential diagnosis of various malfunction. Proper analysis of the size, direction, and rate of the pacing spike and its relation with the intrinsic QRS and paced QRS can easily identify and differentiate various pacemaker malfunctions. Electrocardiogram can also help in identifying concomitant myocardial infarction. All these issues are discussed with representative electrocardiograms. Summary and MCQs at the end of the chapter help in rapid revision and self-assessment.

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References

  1. Vijayraman P, Ellenbogen KA. Bradyarrhythmias and pacemakers. In: Fuster V, Walsh RA, Harrington RA, editors. Hurst’s The Heart. New York: Mc Graw Hill; 2011. p. 1025–57.

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Author information

Authors and Affiliations

  1. Ex Senior professor and head of the department of cardiology, Jawaharlal Nehru Medical College, Ajmer, India

    Sitaram Mittal

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  1. Sitaram Mittal
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Appendices

Summary

  • Hysteresis. This phenomenon is seen in on-demand intermittent pacing. Following an on-demand paced beat, the next paced beat is delayed by few milliseconds, while the pacemaker waits for the next spontaneous cardiac impulse to come. This interval is thus slightly longer than the interval set for regular pacing. This is a normal function and not a pacemaker malfunction.

  • Electromagnetic interference. Any electrical stimulation in the body can change the pacemaker function to VVO mode. This can happen during electrocautery, lithotripsy, diathermy, radio-frequency catheter ablation, transcutaneous electric nerve stimulation, or spinal cord stimulation [5]. This is a normal protection against failure of pacing due to oversensing.

  • Pacing failure. When there is no pacing stimulus in spite of the absence of an expected spontaneous P or QRS, it is called pacing failure. This can be due to oversensing of a noncardiac electric potential, tall T or P waves, lead connection failure, or lead fracture. Magnet application changes pacing to VOO mode with appearance of regular pacing spikes. Magnet application does not restore pacing spikes in the setting of device malfunction.

  • Failure to capture. The presence of a pacemaker stimulus (pacing spike) which is not followed by a paced P wave or QRS complex is known as failure to capture. It is usually due to lead displacement or elevated pacing threshold at the electrode-myocardial interface. Elevation of threshold can be due to fibrosis, ischemia, or infarction around the tip of the pacing lead. Loose screw, insulation break, lead fracture, or battery depletion can also result in failure to capture. Combination of failure to pace and capture usually indicates a pacing system failure.

  • Cross talk. Oversensing of the atrial pacing stimulus by the ventricular lead is known as “cross talk.” It results in inhibition of ventricular pacing.

  • Battery depletion. Automatic decrease in the pacing rate or change of pacemaker function to VOO mode suggests battery depletion.

1.1 Differentiation of Pacemaker Malfunction

  1. (A)

    Pacemaker spike

    1. (1).

      Absent pacemaker spikes

      1. (a)

        QRS faster than the preset pacing rate:

    It happens if patient’s intrinsic heart rate is faster than the pacemaker rate (Figs. 15.20 and 15.21). Applying magnet over the pulse generator converts the pacemaker to asynchronous mode. Appearance of regular spike with intermittent capture suggests normal function (Figs. 15.20 and 15.21).

    1. (b)

      QRS slower than the preset pacing rate:

      • Dry pocket (fibrosis around the pulse generator), battery exhaustion, or lead fracture can reduce the pacing rate.

    1. (2).

      Intermittent absence of pacemaker spikes

      • Lead fracture—fractured ends make intermittent contact. It is not corrected by a magnet.

      • Oversensing of myopotentials or extraneous electric signals.

        It is corrected by use of magnet.

    2. (3).

      Regular pacing spike

      1. (a)

        Rate

        • Rate slower than the preset rate

          • Intermittent—hysteresis

          • Regular—battery depletion, sensing of the T wave, sensing of an echo beat

        • Rate faster than the preset rate—pacemaker-mediated tachycardia (PMT)

      2. (b)

        Amplitude – Large—unipolar unit

        • Small—bipolar unit

        • Smaller than at the time of implantation—lead fracture resulting in high lead impedance

      3. (c)

        Duration – Broad fusions with intrinsic QRS and direct current leakage into the heart due to a short circuit in output circuit

      4. (d)

        Axis – Negative in leads II, III, and aVF—pacing from the right ventricular apex

        • Positive in leads II, III, and aVF—pacing from the right ventricular outflow

        • Change from previous record—displacement

      5. (e)

        Changing direction and amplitude (Figs. 15.22 and 15.23). Insulation fracture

    3. (4).

      Delayed spike after a sensed QRS—hysteresis

  2. (B)

    Distance between the pacing spike and the paced QRS

    • Normally there is no appreciable distance due to rapid entry of the electric impulse in the branches of the conducting system (Fig. 15.24).

    • Increased duration (Fig. 15.24) suggests decreased conduction around the electrode tip. This could be due to ischemia, infarction, or fibrosis.

  3. (C)

    QRS complex

    1. (a)

      Configuration. Left bundle branch block configuration—right ventricular pacing

      Right bundle branch block configuration—left ventricular pacing, biventricular pacing

      Recent change in QRS configuration—displacement

    2. (b)

      Axis. Left upper quadrant—pacing from right ventricular apex

      Inferior—pacing from right ventricular outflow

    3. (c)

      Fusion or pseudo fusion beats do not indicate sensing failure.

  4. (D)

    Sensing failure [ 6 ]

    1. (a)

      Ventricular ectopics arising at a distance from the tip of the lead

    2. (b)

      Low amplitude of QRS of intracardiac electrogram due to infarction, inflammation, or fibrosis

    3. (c)

      Lead displacement, even microdisplacement

    4. (d)

      Myocardial perforation

    5. (e)

      Lead fracture

    6. (f)

      Fault in pulse generator

  5. (E)

    Failure to capture (pacemaker spike without subsequent QRS)

    1. (a)

      Raised threshold—Hypokalemia, hypocalcemia, flecainide

      Ischemia, infarction, fibrosis, inflammation

    2. (b)

      Lead displacement

    3. (c)

      Myocardial perforation

Fig. 15.20
Three sections of the electrocardiogram have an unstable fluctuation where the short upward and downward peaks are labeled as I and S. The starting point of the deep downward peaks are marked as P.

Electrocardiogram from a patient with permanent pacemaker showing fast intrinsic heart rate (I). Application of magnet on the pulse generator results in regular spikes (S) with intermittent fusion beats (F) and paced beats (P). (Reproduced with permission from: Mittal SR. Pacemaker Malfunction. Cardiology Today. 2015;19:180–186) S—pacing spike

Full size image
Fig. 15.21
Two sets of electrocardiograms, A and B. Electrocardiograms of lead first, second, and third. The first lead has very less fluctuation, the second lead has moderate fluctuation and the third fluctuation has downward peaks. S is marked in the short downward fluctuation and starting points of downward fluctuations are marked as P.

(a) Electrocardiogram from a patient with permanent pacemaker with accelerated intrinsic heart rate. (b) Application of magnet over the pulse generator results in appearance of regular spikes (S) with intermittent paced beats (P). (Reproduced with permission from: Mittal SR. Pacemaker Malfunction. Cardiology Today. 2015;19:180–186)

Full size image
Fig. 15.22
Electrocardiograms of lead first, second, third, a V R, a V L, a V F, and V subscript 1 to 6 have unstable fluctuations. An arrow pointing to a blunt peak in V subscripts 4 and 5 and a short downward fluctuation is marked as S.

Electrocardiogram is showing changing direction and amplitude of the pacing spike (marked S). ST segment is elevated in leads V2–V3 (marked as ) suggestive of anterior myocardial infarction. (Reproduced with permission from: Mittal SR. Pacemaker Malfunction. Cardiology Today. 2015;19:180–186)

Full size image
Fig. 15.23
Electrocardiograms of lead first, second, third, a V R, a V L, a V F, and V subscript 1 to 6 have unstable fluctuations. A short downward fluctuation is marked as S.

Electrocardiogram showing changing amplitude of the pacing spikes (marked S). (Reproduced with permission from: Mittal SR. Pacemaker Malfunction. Cardiology Today. 2015;19:180–186)

Full size image
Fig. 15.24
An electrocardiogram of the second lead marks the short upward fluctuation as S and a deep downward peak as Q R S in the fluctuation.

Electrocardiogram from a patient of DDD pacing, showing increased distance between the spike and the paced QRS. (Reproduced with permission from: Mittal SR. Pacemaker Malfunction. Cardiology Today. 2015;19:180–186)

Full size image

MCQs

Q1. Change in the axis of the pacemaker spike as compared to previous ECG suggests:

  1. (a)

    Insulation break

  2. (b)

    Lead fracture

  3. (c)

    Lead displacement

  4. (d)

    All

Q2. Increase in the distance between the pacing spike and onset of the paced QRS as compared to previous ECG could be due to:

  1. (a)

    Ischemia

  2. (b)

    Infarction

  3. (c)

    Fibrosis

  4. (d)

    All

Q3. Change in the QRS configuration from LBBB to RBBB pattern suggests:

  1. (a)

    Lead displacement into right ventricular outflow tract

  2. (b)

    Lead fracture

  3. (c)

    Perforation of interventricular septum

  4. (d)

    Insulation break

Q4. Failure to sense ventricular ectopics with normal sensing of intrinsic cardiac impulse needs:

  1. (a)

    Replacement of pulse generator

  2. (b)

    Change of lead

  3. (c)

    Programming of pulse generator

  4. (d)

    None

Q5. Presence of a pacemaker spike with failure of ventricular depolarization can be due to:

  1. (a)

    Hypokalemia

  2. (b)

    Myocardial perforation

  3. (c)

    Lead fracture

  4. (d)

    Battery exhaustion

Q6. Lead impedance less than 300 ohms suggests:

  1. (a)

    Insulation break

  2. (b)

    Lead fracture

  3. (c)

    Microdisplacement

  4. (d)

    Myocardial perforation

Q7. Lead impedance more than 1200 ohms suggests:

  1. (a)

    Insulation break

  2. (b)

    Lead fracture

  3. (c)

    Poor electrode location

  4. (d)

    Macro displacement

Q8. Lead impedance is not increased by:

  1. (a)

    Lead fracture

  2. (b)

    Poor connection of the lead to the pulse generator

  3. (c)

    Loose set screws

  4. (d)

    Lead displacement

Q9. Diaphragmatic stimulation suggests:

  1. (a)

    Oversensing

  2. (b)

    Insulation rupture

  3. (c)

    Gross change in lead position

  4. (d)

    Myocardial perforation

Q10. Intermittent loss of pacing/sensing suggests:

  1. (a)

    Lead displacement

  2. (b)

    Myocardial perforation

  3. (c)

    Lead fracture

  4. (d)

    Pseudomalfunction

Q11. Delayed spike after sensing of a normal QRS suggests:

  1. (a)

    Hysteresis

  2. (b)

    Sensing malfunction

  3. (c)

    Pacing malfunction

  4. (d)

    All

Q12. Asystole produced by exercising muscles close to the implant site suggests:

  1. (a)

    Sensing failure

  2. (b)

    Pacing failure

  3. (c)

    Oversensing

  4. (d)

    All

Q13. Which cause of low-voltage QRS causes undersensing?

  1. (a)

    Myocardial infarction

  2. (b)

    Pericardial effusion

  3. (c)

    Emphysema

  4. (d)

    Obesity

Q14. Amplitude of intracardiac R wave signal is not reduced in:

  1. (a)

    Lead fracture

  2. (b)

    Microdisplacement

  3. (c)

    Myocardial perforation

  4. (d)

    Emphysema

Q15. Fusion beat suggests:

  1. (a)

    Sensing failure

  2. (b)

    Pacing failure

  3. (c)

    Oversensing

  4. (d)

    Nil

Q16. Regular bradycardia in a patient with permanent pacemaker is not due to:

  1. (a)

    T wave sensing

  2. (b)

    Battery depletion

  3. (c)

    Pacing failure

  4. (d)

    Myopotential inhibition

Q17. Pacemaker-mediated tachycardia can occur in:

  1. (a)

    VVI pacing

  2. (b)

    DDD pacing

  3. (c)

    Biventricular pacing

  4. (d)

    All

Q18. Marked variation in spike amplitude can occur in:

  1. (a)

    Lead fracture

  2. (b)

    Insulation break

  3. (c)

    Oversensing of extracorporeal signals

  4. (d)

    Battery depletion

Q19. Tachycardia in a patient with a DDD pacemaker can be due to:

  1. (a)

    Atrial tachycardia

  2. (b)

    Ventricular tachycardia

  3. (c)

    Pacemaker-mediated tachycardia

  4. (d)

    All

Q20. Deterioration in cardiac status after VVI pacing suggests:

  1. (a)

    Pacing failure

  2. (b)

    Pacemaker syndrome

  3. (c)

    Myocardial ischemia

  4. (d)

    Unmasking of cardiac failure

Q21. Cannon waves in a patient with implanted pacemaker suggest which mode of pacing:

  1. (a)

    AAI

  2. (b)

    VVI

  3. (c)

    DDD

  4. (d)

    Biventricular

Q22. Pacemaker stimulus falling on the T wave of an intrinsic QRS suggests:

  1. (a)

    Sensing failure

  2. (b)

    Pacing failure

  3. (c)

    Failure to capture

  4. (d)

    None

Q23. Failure of appearance of a pacing stimulus in spite of a long pause suggests:

  1. (a)

    Sensing failure

  2. (b)

    Pacing Failure

  3. (c)

    Failure of capture

  4. (d)

    Hysteresis

Q24. Pacemaker stimulus not followed by a paced QRS suggests:

  1. (a)

    Sensing failure

  2. (b)

    Pacing failure

  3. (c)

    Failure of capture

  4. (d)

    Electromagnetic interference

Q25. Atrial pacing stimulus followed by a P wave but not followed by ventricular pacing spike and paced QRS suggests:

  1. (a)

    Hysteresis

  2. (b)

    Failure of capture

  3. (c)

    Electromagnetic interference

  4. (d)

    Cross talk

Q26. Hysteresis suggests:

  1. (a)

    Failure of capture

  2. (b)

    Failure to pace

  3. (c)

    Normal function

  4. (d)

    Failure to sense

Q27. Automatic decrease in the pacing rate of a pacemaker suggests:

  1. (a)

    Hysteresis

  2. (b)

    Electromagnetic interference

  3. (c)

    Failure to sense

  4. (d)

    Battery depletion

Q28. Battery depletion can produce:

  1. (a)

    Failure to sense

  2. (b)

    Failure to pace

  3. (c)

    Change of VVI to VOO mode

  4. (d)

    Hysteresis

Q29. Pacemaker syndrome can occur in:

  1. (a)

    VVI pacing

  2. (b)

    DDD pacing

  3. (c)

    DDDR pacing

  4. (d)

    All

Q30. Pathology at the tissue-lead interface can produce:

  1. (a)

    Failure to sense

  2. (b)

    Failure to capture

  3. (c)

    Failure to pace

  4. (d)

    All

Q31. Lead fracture can cause:

  1. (a)

    Hysteresis

  2. (b)

    Cross talk

  3. (c)

    Electromagnetic interference

  4. (d)

    Sensing failure

Q32. Insulation break can cause:

  1. (a)

    Sensing failure

  2. (b)

    Pacing Failure

  3. (c)

    Failure of capture

  4. (d)

    Hysteresis

Q33. Magnet application over pulse generator changes:

  1. (a)

    VVI to VOO mode

  2. (b)

    VOO mode to VVI mode

  3. (c)

    VVI to DDD mode

  4. (d)

    DDD to VVI mode

Q34. Hysteresis is suggested when a paced beat occurs:

  1. (a)

    Before its scheduled time

  2. (b)

    At its scheduled time

  3. (c)

    Slightly later than the scheduled time

  4. (d)

    Much after the scheduled time

Q35. Electromagnetic interference changes:

  1. (a)

    VOOO to VVI mode

  2. (b)

    VVI to VOO mode

  3. (c)

    DDD to VVI mode

  4. (d)

    None

Answers

(1) c; (2) d; (3) c; (4) d; (5) a, b; (6) a; (7) b; (8) d; (9) d; (10) c; (11) a; (12) c; (13) a; (14) d; (15) d; (16) d; (17) a; (18) a; (19) d; (20) b; (21) b; (22) a; (23) b; (24) c; (25) d; (26) c; (27) d; (28) c; (29) a; (30) a, b; (31) d; (32) a, c; (33) a; (34) c; (35) b

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Mittal, S. (2023). Pacemaker Malfunctions. In: Insights into Electrocardiograms with MCQs. Springer, Singapore. https://doi.org/10.1007/978-981-99-0127-2_15

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  • DOI: https://doi.org/10.1007/978-981-99-0127-2_15

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