How do you evaluate an ECG rhythm?

The rhythm is best analyzed by looking at a rhythm strip . On a 12 lead ECG this is usually a 10 second recording from Lead II. Confirm or corroborate any findings in this lead by checking the other leads. A longer rhythm strip, recorded perhaps recorded at a slower speed, may be helpful.

What is rhythm evaluation?

Rhythms can be evaluated by measuring a few key components of a rhythm strip, the PQRST sequence, which represents one cardiac cycle, the ventricular rate, which is the rate at which the ventricles contract, and the atrial rate, which is the rate at which the atria contract.

What are the 4 main ECG rhythms?

There are four possible electrocardiographic rhythms in cardiac arrest: ventricular fibrillation (VF), pulseless ventricular tachycardia (VT), pulseless electrical activity (PEA), and asystole .

How do you evaluate the heart rhythm?

Some tests that can check for an irregular heart rhythm and associated diseases include: Electrocardiogram (ECG or EKG) . Blood tests to check your electrolyte levels or look for a genetic issue.

How do you evaluate an ECG?

Step 1: Locate the P wave. Step 2: Establish the relationship between P waves and the QRS complex. Step 3: Analyze the QRS morphology. Step 4: Search for other clues. Step 5: Interpret the rhythm in the clinical setting. Aug 31, 2023

How do you know if an ECG is a regular rhythm?

The rhythm can be described in 3 ways : Regular ( metronome like with every beat equally spaced ) Regularly Irregular (every beat not equaly spaced but there is a distinct pattern) Irregularly Irregular (sporadic pattern of beats with no clear spacing)

How to tell if a rhythm is regular or irregular?

Carefully measure from the tip of one R wave to the next, from the beginning to the end of the tracing. A rhythm is considered “regular or constant” when the distance apart is either the same or varies by 1 ½ small boxes or less from one R wave to the next R wave .

Can you tell if your heart is out of rhythm?

It may feel like your heart skipped a beat, added a beat, or is “fluttering.” It might feel like it's beating too fast (which doctors call tachycardia) or too slow (called bradycardia). Or you might not notice anything. Arrhythmias can be an emergency, or they can be harmless.

How to detect irregular heart rhythm?

An electrocardiogram (EKG or ECG) is the most common test for diagnosing arrhythmias . An EKG records your heart's electrical activity. Your doctor may do an EKG during a stress test, which records your heart's activity when it is working hard and beating fast.

What is an abnormal heart rhythm on an ECG?

Abnormal heart rhythms (arrhythmias) are sequences of heartbeats that are irregular, too fast, too slow, or conducted via an abnormal electrical pathway through the heart . Heart disorders are the most common cause of an abnormal heart rhythm.

How do you assess rhythm?

Count the number of QRS complexes that occur within 30 large squares (equivalent to 6 seconds). Multiply this number by 10 to give the estimated rate . For example, if 8 QRS complexes appear within 30 large squares the corresponding rate is 80 bpm. This method can be used for regular and irregular rhythms.

How do you assess rate and rhythm?

The pulse rate is counted by starting at one, which correlates with the first beat felt by your fingers. Count for thirty seconds if the rhythm is regular (even tempo) and multiply by two to report in beats per minute. Count for one minute if the rhythm is irregular.

ECG Rhythm Evaluation (2024)

Chris Nickson
Jun 1, 2023

The rhythm is best analyzed by looking at a rhythm strip. On a 12 lead ECG this is usually a 10 second recording from Lead II.

Confirm or corroborate any findings in this lead by checking the other leads.
A longer rhythm strip, recorded perhaps recorded at a slower speed, may be helpful.

7 step approachto ECG rhythm analysis

1. Rate

Tachycardia or bradycardia?
Normal rate is 60-100/min.

2. Pattern of QRS complexes

Regular or irregular?
If irregular is it regularly irregular or irregularly irregular?

3. QRS morphology

Narrow complex: sinus, atrial or junctional origin.
Wide complex: ventricular origin, or supraventricular with aberrant conduction.

4. P waves

Absent: sinus arrest, atrial fibrillation
Present: morphology and PR interval may suggest sinus, atrial, junctional or even retrograde from the ventricles.

5. Relationship between P waves and QRS complexes

AV association(may be difficult to distinguish from isorhythmic dissociation)
AV dissociation
- complete:atrial and ventricular activity is always independent.
- incomplete:intermittent capture.

6. Onset and termination

Abrupt: suggests re-entrant process.
Gradual: suggests increased automaticity.

7. Response to vagal manoeuvres

Sinus tachycardia,ectopic atrial tachydysrhythmia: gradual slowing during the vagal manoeuvre, but resumes on cessation.
AVNRTorAVRT: abrupt termination or no response.
Atrial fibrillationandatrial flutter: gradual slowing during the manoeuvre.
VT: no response.

Differential Diagnosis

Follow links below for examples of individual rhythms.

Narrow Complex (Supraventricular) Tachycardia

ATRIAL – REGULAR

Sinus tachycardia
Atrial tachycardia
Atrial flutter
Inappropriate sinus tachycardia
Sinus node re-entrant tachycardia

ATRIAL – IRREGULAR

Atrial fibrillation
Atrial flutter with variable block
Multifocal atrial tachycardia

ATRIOVENTRICULAR

Atrioventricular re-entry tachycardia (AVRT)
AV nodal re-entry tachycardia (AVNRT)
Automatic junctional tachycardia

Broad Complex Tachycardia (BCT)

REGULAR BCT

Ventricular tachycardia
Antidromicatrioventricular re-entry tachycardia (AVRT).
Anyregularsupraventricular tachycardia with aberrant conduction— e.g. due to bundle branch block, rate-related aberrancy.

Note: All regular BCTs should be considered to be VT until proven otherwise.

IRREGULAR

Ventricular fibrillation
Polymorphic VT
Torsades de Pointes
AF with Wolff-Parkinson-White syndrome
Anyirregularsupraventricular tachycardia with aberrant conduction — e.g. due to bundle branch block, rate-related aberrancy.

Bradycardia

P WAVES PRESENT

1. Every P wave is followed by a QRS complex (= sinus node dysfunction)

Sinus bradycardia
Sinus node exit block
Sinus pause / arrest

2. Not every P wave is followed by a QRS complex (= AV node dysfunction)

AV block: 2nd degree, Mobitz I (Wenckebach)
AV block: 2nd degree, Mobitz II (Hay)
AV block: 2nd degree, “fixed ratio blocks” (2:1, 3:1)
AV block: 2nd degree, “high grade AV block”
AV block: 3rd degree (complete heart block)

P WAVES ABSENT

Narrowcomplex:Junctional escape rhythm
Broadcomplex:Ventricular escape rhythm

For escape rhythms to occur there must be a failure of sinus node impulse generation or transmission by the AV node.

Advanced Reading

Online

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.

Textbooks

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

ECG LIBRARY

more EKG…

Chris Nickson

Chris is an Intensivist and ECMO specialist at theAlfred ICU in Melbourne. He is also a Clinical Adjunct Associate Professor at Monash University.He is a co-founder of theAustralia and New Zealand Clinician Educator Network(ANZCEN) and is the Lead for theANZCEN Clinician Educator Incubatorprogramme. He is on the Board of Directors for theIntensive Care Foundationand is a First Part Examiner for theCollege of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s educationwebsite,INTENSIVE. He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of theFOAMmovement (Free Open-Access Medical education) and is co-creator oflitfl.com,theRAGE podcast, theResuscitologycourse, and theSMACCconference.

His one great achievement is being the father of three amazing children.

OnTwitter, he is@precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

One comment

P WAVES ABSENT
Narrow complex: Junctional escape rhythm
Broad complex: Ventricular escape rhythm
Two comments
In ventricular escape rhythm P wave are present but not conducted.
One not uncommon cause of bradycardia with absent P waves is Atrial fibrillation with slow ventricular rate P wave are absent.

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