Pacemaker spikes

Pacemaker spikes are usually very sharp and narrow. They may be difficult to see as some ECG machines can filter them out.

See also: Other waves

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Steven Fruitsmaak

Back in 1996, Sgarbossa et al. also studied ST changes in ventricular-paced rhythms. They found that similar criteria was useful in this setting, i.e. concordant ST elevation, concordant ST depression in V1-3, or excessive discordant ST elevation >5mm was also reasonably specific for acute infarction in patients with a ventricular pacemaker. The sensitivity of these signs is low, meaning that you can't rule out infarction based on the absence of these signs.

So far there is limited data available for using this criteria in other wide complex rhythms such as Accelerated Idioventricular Rhythm (AIVR), but there are some case studies suggesting that it might be relevant for these rhythms too. Case studies have also shown that it is possible to see evidence of coronary occlusion in Ventricular Ectopic Beats (VEBs), even if the underlying rhythm does not always show ST changes.

Right Bundle Branch Block (RBBB) doesn't need the Sgarbossa criteria because it doesn't usually have any associated ST elevation. Any ST elevation is suspicious for MI in the presence of a RBBB!

There are some exclusions and limitations of the Sgarbossa criteria. In both of the original studies, patients were excluded if they had severe hypertension, acute heart failure (pulmonary oedema), extreme tachycardia, or hyperkalemia. In these conditions the ECG can be very abnormal but the first priority should be stabilising the patient.ref

Left Ventricular Hypertrophy (LVH) also causes secondary ST changes and in that setting these criteria have not been found to be very sensitive thus far.ref LVH is known to cause variation in ST segments over time even without ischemia, so even comparing with old ECGs can be difficult.ref

It is also important to note that none of these criteria have 100% sensitivity or specificity. There may still be a critical lesion even when the modified criteria are negative. They are probably most useful in stable patients who present with typical chest pain suggestive of MI.ref Serial ECGs, careful monitoring and clinical judgement remain very important in managing these patients.ref

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In the ECGquest archives, this ECG has been tagged with: - Chest pain 12-Lead Excessive discordant ST elevation Pacemaker spikes Ventricular pacemaker Dr Smith's ECG Blog CC BY-NC
Acute chest pain in a patient with cardiomyopathy and a paced rhythm.

This ECG is from a woman in her 70s who was awoken with sharp chest pain on a background of cardiomyopathy, ICD and LVH.

This ECG shows paced rhythm with modified-Sgarbossa positive discordant ST elevation in I, aVL and V2. Angiogram did not find a culprit and echo did not find a wall motion abnormality. The cause remains a mystery.

In the ECGquest archives, this ECG has been tagged with: - Hypotension 12-Lead Pacemaker spikes Wide QRS Ventricular pacemaker Hyperkalemia Dr Smith's ECG Blog CC BY-NC
What will you do for this altered and bradycardic patient? Repeat ECG after transvenous pacemaker

This ECG is from a woman in her 60s who presented from a nursing home with altered mental status, hypotension, hypoxia and bradycardia. This was the repeat ECG after placement of a transvenous pacemaker.

This ECG shows a very wide ventricular paced rhythm with widespread excessive discordant ST elevation. The cause was hyperkalemia.

In the ECGquest archives, this ECG has been tagged with: - Chest pain Dyspnoea 12-Lead Wandering baseline Excessive discordant ST depression. Excessive discordant ST elevation Pacemaker spikes Regular Tachycardia Wide QRS Ventricular pacemaker Multi-vessel disease Dr Smith's ECG Blog CC BY-NC
Can you see through this wide complex rhythm?

This ECG is from a man in his 70s who presented with intermittent dyspnoea and chest pain over the past 2 weeks. He had a history of a pacemaker, heart failure, aortic stenosis, diabetes, hypertension, stroke, ischemic heart disease, chronic kidney disease and peripheral vascular disease. This was his initial ECG.

This ECG shows a wide complex tachycardia with ventricular pacing. The excessively discordant ST changes in V4-6 and aVR suggested diffuse subendocardial ischemia. He was found to have severe three vessel disease and a proximal left circumflex stenosis was stented.

In the ECGquest archives, this ECG has been tagged with: - Syncope 12-Lead Pacemaker spikes Failure to capture ECG of the Week CC-BY-NC-SA
ECG of the Week – 10th September 2018 – Interpretation

This ECG is from a man in his 90s who presented following an episode of syncope.

In the ECGquest archives, this ECG has been tagged with: - 12-Lead LA/RA electrode reversal Bradycardia Extreme Axis Pacemaker spikes Regular Wide QRS Ventricular pacemaker ECG of the Week CC-BY-NC-SA
ECG of the Week – 27th August 2018 – Interpretation
In the ECGquest archives, this ECG has been tagged with: - Dyspnoea 12-Lead Discordant ST changes Excessive discordant ST elevation Pacemaker spikes Ventricular pacemaker Dr Smith's ECG Blog CC BY-NC
Patient with Paced Rhythm in Severe Cardiomyopathy Presents with SOB due to Acute Decompensated Heart Failure

This ECG is from a middle-aged male who presented with paroxysmal nocturnal dyspnoea and hypoxia on a background of heart failure, biventricular pacemaker, ICD and previous LV thrombus.

This ECG shows biventricular paced rhythm with RBBB-like morphology and discordant ST elevation in I, aVL, V3-5 due to acutely decompensated heart failure.

In the ECGquest archives, this ECG has been tagged with: - Chest pain Dizziness 12-Lead Absent P waves Discordant ST changes Left Axis Deviation Pacemaker spikes Wide QRS ECG of the Week CC-BY-NC-SA
ECG of the Week – 2nd April 2018 – Interpretation

This ECG is from a man in his 70s who presented following several episodes of chest pain and dizziness.

In the ECGquest archives, this ECG has been tagged with: - Chest pain 12-Lead Serial 12-lead Anterior ST elevation Concordant ST elevation Excessive discordant ST elevation Left Axis Deviation Normal rate Pacemaker spikes Wide QRS Ventricular pacemaker Acute Anterior MI ECG of the Week CC-BY-NC-SA
ECG of the Week – 25th December 2017 – 60 min later

This ECG is from a woman in her 80s who presented with chest pain. She had a history of 2nd degree AV block with PPM in-situ. This repeat ECG was recorded 60 min after presentation when she had further chest pain.

This ECG shows ventricular pacing with concordant ST elevation in I and V6, and excessive discordant ST elevation in V2-4. The cause was an acute anterior MI.

In the ECGquest archives, this ECG has been tagged with: - Chest pain 12-Lead Concordant ST elevation Discordant ST changes Left Axis Deviation Normal rate Pacemaker spikes Wide QRS Ventricular pacemaker Acute Anterior MI ECG of the Week CC-BY-NC-SA
ECG of the Week – 25th December 2017 – Interpretation

This ECG is from a woman in her 80s presented with chest pain. She had a history of 2nd degree AV block with PPM in-situ. This was the initial ECG.

In the ECGquest archives, this ECG has been tagged with: - Dyspnoea Fatigue 12-Lead Serial 12-lead Excessive discordant ST elevation Pacemaker spikes Ventricular pacemaker Acute Inferior MI Acute Posterior MI Dr Smith's ECG Blog CC BY-NC
See what happens when one fails to diagnose STEMI in LBBB and Paced Rhythm 3 – later that night

This ECG is from a female in her 60s presented with 2-3 days of fatigue and shortness of breath. She called EMS when her symptoms acutely worsened while she was shopping. EMS arrived and recorded a heart rate of 27. On arrival to the ED she was noted to be in complete heart block. She was given atropine with transient increase in HR to 80s. This ECG was recorded later that night after a transvenous pacemaker was placed.

This ECG shows ventricular paced rhythm with excessive discordant ST elevation in II, III and aVF. There is reciprocal depression in aVL and I. The cause was an occluded proximal right coronary artery. This diagnosis was delayed and the patient died.

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