Ventricular escape beat

A ventricular escape beat is an extra beat that originates within the ventricles. The QRS is always wide, because depolarisation does not spread via the normal conduction highways. Unlike a premature beat, an escape beat arrives later than expected.

See also: Extra Beats

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References

  • Making Sense of the ECG: A Hands-on Guide, Third Edition
  • Alila Medical Media
  • Hampton J, Hampton J. The ECG Made Easy. 9th edition. Elsevier

Topics

Sometimes an ECG looks regular except for an extra beat (or two). These extra beats can be harmless, or they can be a critical failsafe preventing a cardiac arrest when the normal conduction fails.

Ectopic beats can originate from any part of the heart.

Atrial ectopic beats

Atrial ectopic beats often have abnormally shaped P waves but the QRS can still be narrow because it is a supraventricular rhythm.

Junctional ectopic beats

Junctional ectopic beats may have no P waves (or the P wave may occur after the QRS) but the QRS can be narrow.

Ventricular ectopic beats

Ventricular ectopic beats are wide because conduction through the ventricles is slow when outside of the normal conduction highways.

Ectopic beats can be divided into those that are early and those that are late. Ectopic beats that arise earlier than the next expected beat can be called Premature beats, e.g. Premature Ventricular Complexes (PVCs). Ectopic beats that arise late can be called Escape beats, .e.g Ventricular Escape Beats (VEBs).

Patients frequently present to us with palpitations, but not all of these require specialist review. Anxious patients often have benign causes to their symptoms, but not always! GPs who are confident in identifying ectopic beats may be able to avoid specialist review unless there are other factors present.

Premature vs. Escape Beats
(Premature) (Escape)

Extra beats can arrive too early (premature beats) or too late (escape beats). Single premature ectopic beats are very common and often benign, even if the patient is aware of them. Patients will often report a slight ‘thump’ – this usually occurs with the beat immediately after the ectopic beat (the heart will pause to reset after the ectopic and the extra filling time creates a stronger beat). Isolated premature beats usually do not require cardiology review if the patient is otherwise well. Risky patients such as known coronary disease or symptoms need assessment (echo +/- stress test). Escape beats are more serious as they suggest there is a significant underlying rhythm problem that the heart is needing to ‘escape’ from – i.e. a serious bradycardia or pause that will require cardiologist input.

Premature Ventricular Complex (PVCs)

PVCs arrive sooner than the next beat is expected. The QRS is very wide and abnormal.

Premature Junctional Complexes

Junctional ectopics have a narrow QRS and either no P wave or a retrograde P wave that occurs after the QRS.

Premature Atrial Complexes (PACs)

PACs have an abnormal P wave shape because they start outside of the SA node. The QRS can be narrow.

Bigeminy and Trigeminy

Premature beats can sometimes occur very frequently, i.e. every second beat (bigeminy) or every third beat (trigeminy). Cardiology review may not be required for this in isolation if the patient is otherwise well. If it is frequent then the patient should have EUC, TFTs, echo +/- stress test for ischaemia.

Non-Sustained VT

If you see a run of 3 or more beats that are fast (>120 bpm) and wide (QRS >3mm), it could be VT. This can cause chest pain, palpitations, syncope, dyspnoea or no symptoms. It is more likely if there is underlying heart disease. Cardiology review is needed if stable, or send to ED if unstable.

Supraventricular Tachycardia (SVT)

Technically any fast arrhythmia with narrow QRS complexes can be called an SVT, but most people think of SVT as the re-entrant tachycardia at the AV node. Patients with SVT are likely to be symptomatic with dizziness, dyspnoea, tachycardia and hypotension during the episode. It may respond to a strong Valsalva manoeuvre. If they are unstable, send them straight to ED. If the SVT has been captured on a Holter monitor, cardiologist input may be required – though if it is really SVT and quite intermittent it may not need referral.

Wolff Parkinson White

Even if the palpitations have resolved, you may be able to see a subtle slurred upstroke to the QRS complex (a delta wave). If this is present, Cardiology review is required to assess for an accessory conduction pathway that may predispose them to arrhythmias.

Patients may present to their GP complaining of (or incidentally noting) recent chest pain that has now resolved. They may also present with other symptoms such as dyspnoea, dizziness, nausea or tiredness that are frequently unrelated to critical cardiac events and do not always require urgent referral to the Emergency Department. GPs have an important gatekeeper role in deciding who goes to ED, who gets referred to a cardiologist’s rooms and who does not need further cardiac investigation.

ST changes

ST elevation or depression tends to happen fast and be very dynamic, so the absence of ST changes is not reassuring in a patient whose symptoms have resolved. Patients can have a normal ECG even with a critical coronary stenosis. If you think they are at high risk for ischemia based on their symptoms and background, they need referral.

T wave changes

Nonspecific ST-T wave changes are common. If possible, try to compare with a previous baseline ECG (and make sure this was done when well and pain free, or it is not a good baseline!). Make sure that the electrodes are placed accurately, else the T waves may be upside down without pathology (see Evil Bunny Ears above).

Pathological Q waves

Pathological Q waves are at least 1mm wide and 25% of the QRS depth. If present and new, they may be a sign of a recent infarction and referral is needed. They can also occur with left ventricular hypertrophy (tall QRS complexes), left bundle branch block or cardiomyopathy (including hypertrophic cardiomyopathy).

Fragmented QRS complex

A fragmented QRS is a fairly recently-discovered sign that can suggest scarring from a completed myocardial infarction – especially if in two leads representing similar anatomical areas. It has one or more extra R or S wave notches. Unlike in bundle branch blocks, the QRS is not wide.

Wellens' syndrome

Wellens’ syndrome features biphasic or inverted T waves in V2-3 in patients whose chest pain has now resolved. This sign is specific for a critical LAD stenosis. These patients should be sent to ED even if their pain has resolved, as they are high risk of imminent occlusion.

Exertional Syncope

Another red flag presentation is a syncopal event during exercise, i.e. fainting during a sports game. There are benign causes but serious causes such as VT / cardiomyopathy / long QT syndrome must be excluded. There is a risk of sudden cardiac death if this is not investigated.

Intermittent AV blocks

Atrioventricular (AV) blocks can be intermittent or fluctuating in severity. If there are signs of a 2nd degree block (i.e. intermittent P waves without a QRS after them), they are at risk of developing complete heart block. Cardiologist input is required – urgently if they are unstable.

Sick Sinus Syndrome

Sinus node dysfunction can be intermittent. Be suspicious with elderly patients who have dizziness, fatigue, palpitations or syncope. The ECG may show bradycardia, pauses, slow AF, paroxysmal tachycardia or it may be normal. Cardiologist review is needed and a Holter monitor may be beneficial.

Hypertension

Hypertensive patients are very common in General Practice, including patients who are infrequent attenders / poorly compliant with medication who may not come to the attention of specialists / inpatient teams while they remain asymptomatic. Having an ECG on file can assist with Cardiovascular Risk Assessment at the 45 year health assessment. There are no strict guidelines about the frequency of ECG monitoring but consider an ECG every 1-2 years for hypertensive patients.

Antipsychotics

Psychotropic medications can affect the QT interval. After they are acutely stabilised, patients with chronic mental health conditions are often discharged back into the care of their GP. Annual ECGs are often recommended to monitor these patients. The QT is abnormal if >400msec in men or >460 msec in women, but >500msec is particularly dangerous. If the heart rate is normal, a useful rule of thumb is that the QT should be less than half the distance between two beats.

Pacemakers & ICDs

Patients who have pacemakers / ICDs should be having 6 monthly device reviews and annual cardiologist reviews. Advanced pacemaker problems are likely beyond the scope of General Practice, but an ECG is likely to be required if they develop symptomatic bradycardia, tachycardia, palpitations, general fatigue or dizziness.

Pre-operative Assessment

All patients over the age of 55 years are currently required to have an ECG before undergoing elective procedures.

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