wandering pacemaker ecg strip will

Wandering Atrial Pacemaker EKG Interpretation with Rhythm Strip

Ekg features, wandering atrial pacemaker ekg interpretation example.

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Wandering Atrial Pacemaker ECG Interpretation #312

Description.

• Rhythms are often named according to the origin of the electrical activity in the heart or the structure where the problem is occurring.
• Wandering Atrial Pacemaker is aptly named due to the electrical impulses causing the atrial activity are moving or wandering.
• These changes in the locus of stimulation affect the morphology of the P waves.
• In Wandering Atrial Pacemaker ECG, you must observe at least three different shaped P waves. No other changes in the tracing may be observed. The rhythm may or may not be regular.
• The PR interval is often affected, but does not have to be.
• The bottom line, is you must observe at least three different shaped P waves.

Practice Strip

Analyze this tracing using the five steps of rhythm analysis.

• Rhythm: Irregular
• P wave: Changing Shapes (3 or more)
• PR interval: Variable
• Interpretation: Wandering Atrial Pacemaker

Authors and Reviewers

• ECG heart rhythm modules: Thomas O'Brien.
• ECG monitor simulation developer: Steve Collmann
• 12 Lead Course: Dr. Michael Mazzini, MD .
• Spanish language ECG: Breena R. Taira, MD, MPH
• Medical review: Dr. Jonathan Keroes, MD
• Medical review: Dr. Pedro Azevedo, MD, Cardiology
• Last Update: 11/8/2021
• Electrocardiography for Healthcare Professionals, 6th Edition Kathryn Booth and Thomas O'Brien ISBN10: 1265013470, ISBN13: 9781265013479 McGraw Hill, 2023
• Rapid Interpretation of EKG's, Sixth Edition Dale Dublin Cover Publishing Company
• EKG Reference Guide EKG.Academy
• 12 Lead EKG for Nurses: Simple Steps to Interpret Rhythms, Arrhythmias, Blocks, Hypertrophy, Infarcts, & Cardiac Drugs Aaron Reed Create Space Independent Publishing
• Heart Sounds and Murmurs: A Practical Guide with Audio CD-ROM 3rd Edition Elsevier-Health Sciences Division Barbara A. Erickson, PhD, RN, CCRN
• The Virtual Cardiac Patient: A Multimedia Guide to Heart Sounds, Murmurs, EKG Jonathan Keroes, David Lieberman Publisher: Lippincott Williams & Wilkin) ISBN-10: 0781784425; ISBN-13: 978-0781784429
• Project Semilla, UCLA Emergency Medicine, EKG Training Breena R. Taira, MD, MPH
• ECG Reference Guide PracticalClinicalSkills.com

This website provides professional medical education. For medical care contact your doctor. 2024 ©MedEdu LLC. All Rights Reserved. Terms & Conditions | About Us | Privacy | Email Us | 1

Thursday, March 4, 2021

Blog #200 — wandering pacemaker (vs mat).

There is no clinical information is available for the ECG and 2-lead rhythm strip shown below in  Figure-1 .

• HOW would you interpret this tracing?
• What treatment is likely to be needed? 

====================================

Editorial  Comment:

It is always challenging to interpret tracings without the benefit of clinical information. That said — this situation is common in clinical practice. My experience in this area derives from the 30 years during which I was charged with interpreting  all  ECGs ordered by 35 medical providers at a primary care clinic — as well periodic stints during which I interpreted hospital tracings without the benefit of any history. 

• The challenge lies with having to decide  which  tracings in the  “pile of ECGs to be interpreted”  were those for which I needed to pull the medical chart ( or call the provider ) because of ECG findings of immediate potential concern.
• Obvious time constraints made it impossible to pull the chart for each ECG that I was given to read ( I’d never get anything else done if I did so ).
• I therefore became well versed in the skill of limiting the charts that I would pull to those patients whose ECGs showed findings I thought were important  and  potentially indicative of an acute situation that may have been overlooked.

=====================================

MY Thoughts  on the ECG in Figure-1:

As always — systematic interpretation of  any  ECG should begin with assessing the cardiac rhythm. In general —  lead II  and  lead V1  are the 2  best  leads on a 12-lead tracing for assessing atrial activity — and we have the advantage in  Figure-1  of a  simultaneously-recorded  2-lead rhythm strip of both of these leads.  By the  Ps ,  Qs and  3R Approach:

• The rhythm in  Figure-1  is  clearly   irregular .
• The  QRS  complex is  narrow ( ie,  not  more than half a large box in duration = ≤0.10 second ) . 
• The rate  varies  from  50 /minute — to just under  100 /minute.
• More than 1 P wave morphology is present . That said — P waves  do  appear to be related to neighboring QRS complexes, because the PR interval for the P wave shapes that we see remains constant  ( See   Figure-2 ) .

MY Thoughts  on Figure-2:

There are 2 different P wave shapes in  Figure-2 .

• The tracing begins with  3  sinus  beats ( ie,  RED arrows highlight 3 similar-looking upright-in-lead-II P waves — all with the same PR interval ) .
• P wave shape then changes  for beats #4, 5 and 6  ( ie,  BLUE arrows highlighting an almost isoelectric, if not negative P wave with fixed PR interval ) .
• The atrial focus then shifts back , with return to sinus P waves for beats #7, 8, 9 and 10 (ie,  return of RED arrows highlighting similar-looking, upright P waves in lead II — albeit with variability in the R-R interval ).
• The rhythm in  Figure-2  concludes with a  slowing-down  of the ventricular rate, as  the 2nd atrial focus returns , in which the P wave is almost isoelectric (ie,  BLUE arrows for beats #11 and 12 ).

BOTTOM LINE  regarding  Figure-1:  The rhythm in  Figure-2  is most consistent with a  Wandering  Atrial  Pacemaker . This is because the change from one atrial site to the next occurs gradually over a period of several beats.

• PEARL:  The reason it is uncommon ( if not rare ) in clinical practice to see a wandering atrial pacemaker — is that most providers do not pay  long enough  attention to  beat-to-beat  change in P wave morphology needed to identify  gradual  shift between  at least  3 different atrial sites.

SUMMARY:  Review of the  KEY  features of wandering atrial pacemaker is the theme below for our  ECG  Media  Pearl #17 ( a 3:30 minute audio recording ).

• Written review of wandering pacemaker appears below in  Figure-3 .
• Review of  MAT  is covered in our  ECG Blog #199 .

Today’s   E CG  M edia   P EARL  # 17 ( 3:30 minutes   Audio )  —   What is a  Wandering  Atrial Pacemaker ( as opposed to MAT )?

A DDENDUM   ( 3/4/2021 ) :

I received the following note from  David Richley  regarding today’s tracing: “I think I would use different terminology to describe this because to me the atrial pacemaker doesn’t so much ‘wander’ as ‘jump’. I would describe this as sinus arrhythmia with junctional escape rhythm at 60-65/minute every time the sinus node discharge rate slows to below that rate. I interpret the escape beats as junctional rather than atrial, because athough the P waves, ( which are initially negative in II, aVF and V4-V6 — and positive in aVR ) precede the QRS — the PR segment is very short, suggesting an AV nodal origin. However, we describe this phenomenon — I do agree that it’s likely to be completely benign.

MY Thoughts:  Dave’s comment is one of the reasons why:  i )  The diagnosis of wandering pacemaker requires clear demonstration of shift in the atrial pacemaker in  at least  3 different sites. We  only  see 2 different sites here;  and ,  ii )  The diagnosis of wandering atrial pacemaker is  not  common. 

• It’s impossible to rule out Dave’s theory from the single tracing we have.
• That said — the BLUE arrow P wave site may or may not be of AV nodal origin ( you can see a similar, near-isoelectric P wave with short PR interval from a low atrial site ).
• I also considered the possibility of the BLUE arrow P waves representing junctional escape — but decided against it because the difference in R-R interval from what we see between beats #9-10  vs  what we see between beats #10-11 is  more  than what I’d expect based on the cadence of rate variation I see from beats #7-10.
• Bottom Line:  We both agree there is a shift in the pacemaker site in a rhythm that is likely to be benign. And, we both agree that additional monitoring would be needed for a definitive response.  THANK YOU Dave!

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Wandering Atrial Pacemaker

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Key features, clinical presentation, diagnostic evaluation, ongoing management.

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ESSENTIALS OF DIAGNOSIS

Progressive cyclic variation in P-wave morphology

Heart rate 60–100 bpm

Variation of P-wave morphology, P-P interval, and P-R interval

GENERAL CONSIDERATIONS

This rhythm is benign

This rhythm and multifocal atrial tachycardia are similar except for heart rate

The other possible explanation is that there is significant respiratory sinus arrhythmia, with uncovering of latent foci of pacemaker activity

Usually, it is associated with underlying lung disease

In the elderly, it may be a manifestation of sick sinus syndrome

In the young and athletic heart, it may represent enhanced vagal tone

SYMPTOMS AND SIGNS

Usually causes no symptoms and is incidentally discovered

Occasional patient may feel skipped beats

PHYSICAL EXAM FINDINGS

Variable S 1

DIFFERENTIAL DIAGNOSIS

Multifocal atrial tachycardia (heart rate > 100 bpm)

Frequent premature atrial complexes and atrial bigeminy

LABORATORY TESTS

None specific

ELECTROCARDIOGRAPHY

ECG to document rhythm

CARDIOLOGY REFERRAL

Not required

MEDICATIONS

No specific treatment

Monitor and treat the underlying cause, such as sick sinus syndrome or lung disease

DIET AND ACTIVITY

No restrictions

General healthy lifestyle

Once a year if sinus node abnormality is suspected; otherwise when symptoms arise

COMPLICATIONS

May progress to sick sinus syndrome

This condition by itself is benign

PRACTICE GUIDELINES

Indications for pacemaker:

– If part of sick sinus syndrome

– If associated with documented symptomatic bradycardia

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Practice Rhythm Strips

This ECG strip shows the classic changes of a wandering atrial pacemaker. Notice the slow, gradual transition of the P waves from upright to inverted. Longer strips show the transition occurring back and forth between the pacemakers. Notice that the QRS complexes and T waves are identical in this strip. There is no evidence of any aberrant conduction, as can sometimes occur with faster rates.

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Pacemakers and Cardiac Devices

• Introduction to Cardiac Pacing and Devices: Pacemaker, ICD, CRT
• Components and construction of a pacemaker
• Basic cardiac pacing, pacemaker functions and settings
• Indications for pacemaker

Interpretation of Pacemaker ECG

• Assessment of Pacemaker Malfunction

Interpreting pacemaker ECGs

Assessing pacemaker function requires knowledge of the mode of pacing, and careful analysis of ECG tracings. Most modern devices are capable of transmitting ECG tracings continuously to cloud-based platforms, which enables the clinician to examine intracardiac ECGs at any time. However, most clinicians who encounter patients with pacemakers only have access to conventional surface ECGs. Being able to assess pacemaker function and perform troubleshooting should be considered a basic clinical skill.

Chapter content

Pacing activity may be visible or invisible, depending on e.g the type of pacemaker, intrinsic cardiac activity, etc. The cardinal manifestation of pacing on surface ECG is the stimulation artifact (Figure 1). In atrial pacing, the stimulation artifact precedes the P-wave. In ventricular pacing, the stimulation artifact precedes the QRS complex. Two artifacts are seen if both chambers are paced. The stimulation artifact is larger in unipolar pacing , as compared with bipolar pacing . The latter yields a discrete stimulation artifact, which may be visible in one or a few leads.

In addition to stimulation artifacts, ventricular pacing yields wide QRS complexes with LBBB morphology (i.e left bundle branch block appearance). This is explained by the fact that, as in LBBB, the left ventricle receives the depolarizing impulse from the right ventricle (where the pacemaker delivers the pulses). The depolarizing wave spreads outside the conduction system, which is considerably slower, as compared with impulse transmission within the conduction system (His-Purkinje network).

Assessing pacemaker function

The base rate is the lowest heart rate allowed by the pacemaker; intrinsic cardiac activity below the base rate will trigger pacing. The base rate is usually set to 60 beats/min. The base rate is virtually always >50 beats/min, meaning that any heart rate below 50 beats/min is most likely not paced. An intrinsic heart rate faster than the base rate should inhibit the pacemaker.

The appearance of the P-wave depends on where the atrial lead is fixed. Typically, the atrial lead is fixed next to the right atrial appendage, or atrial ceiling, which yields P-waves similar to those seen during normal sinus rhythm (i.e, positive P-wave in lead II). If the atrial lead is placed distally in the atrium, activation may proceed in the opposite direction, which results in negative (retrograde) P-waves in lead II.

QRS Complex

QRS morphology also depends on where the pacing stimulus is delivered. Typically, the lead tip is fixed apically in the right ventricle; activation starts in the right ventricle and spreads slowly to the left ventricle. As mentioned above, this is similar to the situation in left bundle branch block (LBBB) , which explains why paced QRS complexes are similar to the QRS morphology during LBBB.

Stimulation in other regions of the ventricle may result in a different QRS morphology. If the lead tip is fixed in the septum, the impulse may actually enter the conduction system (His-Purkinje network), which results in rapid impulse transmission and thus shorter QRS duration (as compared with apical pacing).

Because ventricular pacing results in abnormal depolarization, repolarization will also be abnormal, resulting in discordant ST-T segments (i.e the QRS complex and T-wave display opposite directions).

Below follows ECG tracings demonstrating these aspects.

ECG in biventricular pacing (CRT)

In biventricular pacing, stimulation occurs in both the right and left ventricle. With simultaneous atrial spacing, a total of three stimulation artifacts can be seen on surface ECG. Stimulation of the right and left ventricle need not occur exactly at the same time. The purpose of biventricular pacing is to synchronize ventricular contraction. This mode of pacing, referred to as cardiac resynchronization therapy (CRT), reduces morbidity and mortality in chronic systolic heart failure with a wide QRS complex. CRT does not, however, reduce morbidity and mortality in patients with QRS duration of less than 130 msec (1-4).

Fusion and pseudofusion

Fusion implies that the ventricle is simultaneously depolarized by the pacemaker stimulus and the intrinsic impulse passing through the His-Purkinje system. Fusion occurs if the pacemaker fails to sense intrinsic ventricular depolarization. It can also occur if the pacemaker senses the intrinsic depolarization too late.

Because the ventricle is activated both by the pacemaker stimulus and the intrinsic impulse, the QRS morphology resembles a fusion between a normal beat and a paced beat (Figure 8A).

Pseudofusion occurs in the same situations as fusion, but the depolarization from the pacemaker stimulus fails to spread through the myocardium (because it is refractory after conducting the intrinsic impulse). A stimulation artifact is seen, but the QRS complex is not affected (Figure 8B).

Acute myocardial infarction in a patients with pacemakers

Atrial pacing does not affect the QRS and ST-T segment. Thus, atrial pacing does not affect the interpretation of myocardial ischemia on ECG.

Ventricular pacing, however, results in a wide QRS complex and secondary ST-T-changes, which complicates detection of ischemia. As in left bundle branch block, these secondary ST-T changes may mask or mimic acute myocardial ischemia . There are three methods to approach this problem:

• Temporarily inactivate the pacemaker , if the patient has intrinsic cardiac activity. This potentially allows for examination of the ST-T segments during normal depolarization and repolarization. Note that switching off the pacemaker is a risky procedure, and cardiac memory may result in persisting ST-T changes even during normal ventricular depolarization. Cardiac T-wave memory implies that ST-T changes seen during pacing persist for a period after pacing is inactivated.
• Compare the current ECG tracing with previous tracings , in order to evaluate ST-T changes. Such changes may suggest ongoing ischemia.
• Use the Sgarbossa criteria , although they have not yet been validated for paced rhythms.

Pacemaker malfunction, including ECG interpretation , is discussed in the next chapter.

• Ruschitzka et al (N Engl J Med 2013; 369:1395-1405) – Cardiac-Resynchronization Therapy in Heart Failure with a Narrow QRS Complex
• Goldenberg et al (N Engl J Med 2014; 370:1694-1701) – Survival with Cardiac-Resynchronization Therapy in Mild Heart Failure
• Tang et al (N Engl J Med 2010; 363:2385-2395 – Cardiac-Resynchronization Therapy for Mild-to-Moderate Heart Failure
• Moss et al (N Engl J Med 2009; 361:1329-1338) – Cardiac-Resynchronization Therapy for the Prevention of Heart-Failure Events.

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Wandering Pacemaker

When several pacemakers are competing, p-waves with different origins and thus configurations occur. The rhythm is slightly different from beat to beat.

note If the heart rate increases to above 100bpm, it is called Multifocal Atrial Tachycardia . Possible causes are hypoxia, COPD and medication such as digoxin.

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Pacemaker Rhythms – Normal Patterns

• Ed Burns and Robert Buttner
• Jul 7, 2022

Pacemaker Components

1. pulse generator.

• Power source
• Control circuitry
• Transmitter / Receiver
• Reed Switch (Magnet activated switch)
• Single or multiple
• Unipolar or bipolar

Pacemaker Classification

• Pacemakers are classified by the nature of their pacing mode.
• Classification follows pacemaker code developed by the North American Society of Pacing and Electrophysiology (NASPE) and the British Pacing and Electrophysiology Group (BPEG).
• The NASPE/BPEG Generic (NBG) Pacemaker Code was last revised in 2002, although many textbooks still use the previous version from 1987.
• The code is expressed as a series of up to five letters.

NBG Pacemaker Code (2002)

• Refers to chambers paced.
• Refers to the location where the pacemaker senses native cardiac electrical activity.
• Refers to pacemakers response to sensed native cardiac activity.
• T = Sensed activity results in triggering of paced activity
• I = Sensed activity results in inhibition of pacing activity
• Indicates ability for rate modulation designed to altered heart appropriately to meet physiological needs e.g. physical activity. Sensors may measure and respond to variables including vibration, respiration, or acid-base status.
• Allows indication of multiple stimulation sites within one anatomical area e.g. more than one pacing site within the atria or biatrial pacing

• Same as 2002 guidelines.
• Reflects the programming options available for pacemaker set-up or presence of rate modulation ability.
• Refers to presences of anti-tachydysrhythmia functions. Superseded by the NASPE/BPEG Defibrillator Code.

Common Pacing Modes

AAI – Atrial pacing and sensing

• If native atrial activity sensed then pacing is inhibited.
• If no native activity sensed for pre-determined time then atrial pacing initiated.
• Used in sinus node dysfunction with intact AV conduction.
• Also termed atrial demand mode.

VVI – Ventricle pacing and sensing

• Similar to AAI mode but involving ventricles instead of the atrium.
• Used in patients with chronic atrial impairment e.g. atrial fibrillation or flutter.

DDD – pacing and sensing the atria and ventricles

• Commonest pacing mode.
• Atrial pacing occurs if no native atrial activity for set time.
• Ventricular pacing occurs if no native ventricle activity for set time following atrial activity.
• Atrial channel function is suspend during a fixed periods following atrial and ventricular activity to prevent sensing ventricular activity or retrograde p waves as native atrial activity.

Magnet mode

• Applying a magnet to a pacemaker will initiate the magnet mode.
• This mode varies with pacemaker set-up and manufacturer.
• Usually initiates an asynchronous pacing mode – AOO, VOO, or DOO.
• Asynchronous modes deliver constant rate paced stimuli regardless of native rate of rhythm.
• In asynchronous ventricle pacing there is a risk of pacemaker-induced ventricular tachycardia.
• Note this differs from magnet application to an Implantable Cardioversion Defibrillator (ICD) which results in defibrillator deactivation.

Criteria for Pacemaker Insertion

• The 2002 American College of Cardiology, American Heart Association and North American Society for Pacing and Electrophysiology guidelines for implantation of cardiac pacemakers .
• ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities

Paced ECG – Electrocardiographic Features

The appearance of the ECG in a paced patient is dependent on the pacing mode used, placement of pacing leads, device pacing thresholds, and the presence of native electrical activity. Features of the paced ECG are: Pacing spikes

• Vertical spikes of short duration, usually 2 ms.
• May be difficult to see in all leads.
• Amplitude depends on position and type of lead.
• Bipolar leads result in a much smaller pacing spike than unipolar leads.
• Epicardially placed leads result in smaller pacing spikes than endocardially placed leads.

Atrial Pacing

• Pacing spike precedes the p wave.
• Morphology of p wave dependent of lead placement but may appear normal.

Ventricular Pacing

• Pacing spike precedes the QRS complex.
• Right ventricle pacing lead placement results in a QRS morphology similar to LBBB .
• Left epicardial pacing lead placement results in a QRS morphology similar to RBBB .
• ST segments and T waves should be discordant with the QRS complex i.e. the major terminal portion of the QRS complex is located on the opposite side of the baseline from the ST segment and T wave.

Dual Chamber Pacing

• Dependent on areas begin paced.
• May exhibit features of atrial pacing, ventricular pacing or both.
• Pacing spikes may precede only p wave, only QRS complex, or both.

The absence of paced complexes does not always mean pacemaker failure as it may reflect satisfactory native conduction. ECG Features

ECG Examples

A-V sequential pacing:

• Atrial and ventricular pacing spikes are visible before each QRS complex.
• There is 100% atrial capture — small P waves are seen following each atrial pacing spike.
• There is 100% ventricular capture — a QRS complex follows each ventricular pacing spike.
• QRS complexes are broad with a LBBB morphology, indicating the presence of a ventricular pacing electrode in the right ventricle.

• A-V sequential pacing — atrial and ventricular pacing spikes precede each QRS complex with 100% capture.

• Another example of A-V sequential pacing.

Ventricular paced rhythm:

• Ventricular pacing spikes precede each QRS complex (except perhaps complex #2 — although the QRS morphology in this complex is identical to the rest of the ECG, suggesting that this beat is also paced)
• No atrial pacing spikes are seen.
• The underlying native rhythm is probably coarse atrial fibrillation — there are several possible P waves visible in V1 but otherwise the atrial activity is chaotic.

• Ventricular pacing spikes precede most of the QRS complexes.
• The 6th and 7th beats are narrower, with a different morphology — these are non-paced (“capture”) beats, probably supraventricular in origin.
• There is a pacing spike superimposed on beat #6, but this does not appear to alter its morphology — i.e. no evidence of a fusion complex.

• Ventricular pacing spikes precede the QRS complexes, most of which exhibit LBBB morphology consistent with a RV pacing electrode.
• The 5th, 6th and 11th complexes are narrower with a different morphology — these are fusion beats produced when the ventricle is simultaneously activated by both paced and supraventricular (native) impulses. You can see how the pacing spike is shortened and the QRS duration narrowed by the co-incident native impulse.
• The 4th complex is probably a supraventricular capture beat , although there may still be some hybridisation with a pacing spike.

Atrially paced patients often have evidence of 1st degree AV block or Wenckebach conduction on their paced ECG that is not apparent on their baseline tracing.

This is because the sort of patients that require atrial pacing (e.g. post-op cardiac surgery) commonly have some degree of AV node dysfunction (e.g. due to age-related AV-nodal degeneration / their underlying cardiac condition / post-operative ischaemia / AV-nodal blocking drugs).

When these patients are paced at a faster rate than their AV node can handle, the AV node becomes “fatigued” resulting in 1st degree AV block or Wenckebach phenomenon on the paced ECG. This abnormality is not clinically important provided that the patient’s cardiac output is not compromised.

Atrial paced rhythm with 1st degree AV block:

• There are regular pacing spikes at 90 bpm.
• Each pacing spike is followed by a P wave, indicating 100% atrial capture.
• P waves are conducted to the ventricles with a prolonged PR interval (280 ms).

Atrial paced rhythm with Wenckebach conduction:

• There are regular atrial pacing spikes at 90 bpm; each one is followed by a small P wave indicating 100% atrial capture.
• However, not every P wave results in a QRS complex — the PR interval progressively lengthens, culminating in failure of AV conduction (“dropped QRS complexes”).
• There is a co-existent 2nd degree AV block with Mobitz I conduction (Wenckebach phenomenon).
• The Mobitz I is due to the patient being paced at a rate faster than his AV node can handle — at his own intrinsic rate of 50-60 bpm he had only a 1st degree AV block.

To find out the story behind this ECG, check out ECG Exigency 011 .

Pacemaker Puzzler

Can you work out what is going on in this ECG?

• There is an irregularly irregular rhythm with multiple atrial and ventricular pacing spikes.
• The majority of the QRS complexes are broad (120ms) and preceded by ventricular pacing spikes.
• The LBBB morphology is consistent with a ventricular pacing electrode located in the right ventricle.

The varying relationship between the atrial and ventricular pacing spikes is best understood by examining the lead II rhythm strip (below):

• Beat 1 is narrow — this appears to be a native ventricular complex triggered by an atrial pacing spike. This indicates that AV conduction is intact to some degree (i.e. 3rd degree AV block cannot be present).
• Beat 9 is broad with a completely different morphology and axis to the rest of the strip — this is a ventricular ectopic beat.
• Beats 3, 6, 8, 10 and 12 are preceded by both atrial and ventricular pacing spikes — sequential A-V pacing.
• Beats 2, 4, 5, 7 and 11 are preceded by ventricular pacing spikes only. The absence of atrial pacing spikes suggests that the pacemaker is responding to native supraventriclar impulses.
• Given the absence of discernible P waves and the very irregular rhythm, it is likely that the underlying native rhythm is atrial fibrillation.

• Atrial fibrillation with DDD pacing and occasional ventricular ectopics.

Related Topics

• Pacemaker essentials: Medmastery
• Pacemaker malfunction
• Left bundle branch block
• Right bundle branch block
• Sgarbossa Criteria
• Bernstein AD, Camm AJ, Fletcher RD, Gold RD, Rickards AF, Smyth NP, Spielman SR, Sutton R. The NASPE/BPEG generic pacemaker code for antibradyarrhythmia and adaptive-rate pacing and antitachyarrhythmia devices . Pacing Clin Electrophysiol. 1987 Jul;10(4 Pt 1):794-9.
• Bernstein AD, Daubert JC, Fletcher RD, Hayes DL, Lüderitz B, Reynolds DW, Schoenfeld MH, Sutton R. The revised NASPE/BPEG generic code for antibradycardia, adaptive-rate, and multisite pacing. North American Society of Pacing and Electrophysiology/British Pacing and Electrophysiology Group . Pacing Clin Electrophysiol. 2002 Feb;25(2):260-4
• Gregoratos G et al. ACC/AHA/NASPE 2002 guideline update for implantation of cardiac pacemakers and antiarrhythmia devices: summary article: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (ACC/AHA/NASPE Committee to Update the 1998 Pacemaker Guidelines) . Circulation. 2002 Oct 15;106(16):2145-61

Advanced Reading

• Wiesbauer F, Kühn P. ECG Mastery: Yellow Belt online course. Understand ECG basics. Medmastery
• Wiesbauer F, Kühn P. ECG Mastery: Blue Belt online course : Become an ECG expert. Medmastery
• Kühn P, Houghton A. ECG Mastery: Black Belt Workshop . Advanced ECG interpretation. Medmastery
• Rawshani A. Clinical ECG Interpretation ECG Waves
• Smith SW. Dr Smith’s ECG blog .
• Zimmerman FH. ECG Core Curriculum . 2023
• Mattu A, Berberian J, Brady WJ. Emergency ECGs: Case-Based Review and Interpretations , 2022
• Straus DG, Schocken DD. Marriott’s Practical Electrocardiography 13e, 2021
• Brady WJ, Lipinski MJ et al. Electrocardiogram in Clinical Medicine . 1e, 2020
• Mattu A, Tabas JA, Brady WJ. Electrocardiography in Emergency, Acute, and Critical Care . 2e, 2019
• Hampton J, Adlam D. The ECG Made Practical 7e, 2019
• Kühn P, Lang C, Wiesbauer F. ECG Mastery: The Simplest Way to Learn the ECG . 2015
• Grauer K. ECG Pocket Brain (Expanded) 6e, 2014
• Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice: Adult and Pediatric 6e, 2008
• Chan TC. ECG in Emergency Medicine and Acute Care 1e, 2004

LITFL Further Reading

• ECG Library Basics – Waves, Intervals, Segments and Clinical Interpretation
• ECG A to Z by diagnosis – ECG interpretation in clinical context
• ECG Exigency and Cardiovascular Curveball – ECG Clinical Cases
• 100 ECG Quiz – Self-assessment tool for examination practice
• ECG Reference SITES and BOOKS – the best of the rest

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Emergency Physician in Prehospital and Retrieval Medicine in Sydney, Australia. He has a passion for ECG interpretation and medical education | ECG Library |

Robert Buttner

MBBS (UWA) CCPU (RCE, Biliary, DVT, E-FAST, AAA) Adult/Paediatric Emergency Medicine Advanced Trainee in Melbourne, Australia. Special interests in diagnostic and procedural ultrasound, medical education, and ECG interpretation. Editor-in-chief of the LITFL ECG Library . Twitter: @rob_buttner

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