EKG Rhythms. Best Arrhythmia Interpretation Guide with Practice Strips & Quiz

EKG Rhythms Interpretation can be tricky especially when it comes to the uncommon ones. With enough understanding of  distinct features of each rhythm, it becomes an easy and fun task. This is a detailed ECG guide with practice quiz and strips to help you master EKG interpretation. It is a critical skill that every nurse and healthcare practitioner should master to be safe, be able to predict pathology, prevent lethal events and save lives. You must be good at EKG interpretation to be good or pass ACLS

This detailed guide covers almost every rhythm any nurse or clinician will ever need to worry about.

This guide gets will only get better with your comments and contribution. Please make sure to leave comments and share with a friend

Please notice that some of the rhythms discussed here are rarely tested because they do not have urgent medical significance. We also have a 12 lead EKG lesson for advanced users

There are 2 ways of classifying EKG rhythms making it a whole lot easier to interpret any rhythm presented to you, be it in clinical setting, in class, ACLS or in an EKG Rhythm Test. I have even included a rhythm practice strips with answers and explanation.

Here are the 2 ways to classify EKG Rhythms;

Stay with me here….

Heart Arrhythmia Classifications

 

  1. Classification based on Rhythm rate and pulse. This might not be the best way to classify them all. The second method is better.
    • Pulseless Rhythms.

      These are also called lethal EKG rhythm demanding immediate action in Basic life skills algorithms (BLS) and/or Advanced Cardiac Life Support (ACLS) algorithms. Notice that some bradyarrhythmias below are also classified as lethal arrhythmia

      • Asystole
      • Ventricular tachycardia
      • Ventricular fibrillation
      • Torsade de Pointes
      • Pulseless Electrical Activity (PEA)
    • Bradyarrythmias:

      These are cardiac rhythms that are slower than 60 beats a minute. Most of them either originate from Atria-ventricular node, Bundle of His or purkije fibers.

      • Sinus Bradycardia
      • 1st Degree Atrio-Ventricular Block
      • 2nd Degree Atrio-Ventricular Block type 1 (Wincheback)
      • 2nd Degree Atrio-Ventricular Block type 2
      • 3rd Degree Atrio-Ventricular Block
      • Junctional Rhythm
      • Idioventricular Rhythm – Lethal arrhythmia
    • Tachyarrythmias:

      These are cardiac rhythms associated with fast heart rate above 100 beats a minute.

      • Sinus Tachycardia
      • Supraventricular Tachycardia (SVT) / Narrow Complex Tachycardia (NCT)
      • Atrial Fibrilation (A-Fib) – Can be controlled under 100 beats
      • Atrial Flutter (A-Flutter) – Atrial rhythm usually as high as 350 beats a minute but the ventricular rhythm is usually less than 100 causing loss of “Atrial Kick”
  2. The second method of classifying EKG Rhythm is based on the origin of the impulse. This is a better way to classify EKG Rhythms than the one above.

Stay with me…. Here we go:

Rhythms originating from Sinoatrial Node:

Sinus Arrest:

Sinoatrial arrest AKA sinus arrest or sinus pause occurs when the the sinoatrial node of the heart transiently ceases to fire. The results is a missed beat.

Characteristics of Sinus Arrest

RhythmIrregular due to pause
RateNormal or slow
P waveNormal
PR IntervalNormal (0.12-0.20 sec)
QRSNormal (0.06-0.10 sec)
Notes/CausesPause time is not an integer multiple of the P-P interval

Sinus Arrhythmia

RhythmIrregular, varying with respiration
RateNormal (60-100 bpm) and rate may increase during inspiration
P WaveNormal
PR IntervalNormal (0.12-0.20 sec)
QRSNormal (0.06-0.10 sec)
NotesHeart rate frequently increases with inspiration, decreasing with expiration
RhythmRegular
RateSlow (< 60 bpm)
P WaveNormal
PR IntervalNormal (0.12-0.20 sec)
QRSNormal (0.06-0.10 sec)
Notes Unless dealing with a trained athlete or asymptomatic patient, think about the underlying cause
RhythmRegular
RateFast (> 100 bpm)
P WaveNormal, may merge with T wave at very fast rates
PR IntervalNormal (0.12-0.20 sec)
QRSNormal (0.06-0.10 sec)
NotesQT interval shortens with increasing heart rate. Treat the underlying cause. Maybe normal depending on age (pediatrics and neonates)

 

EKG Rhythms originating from Atrium. (Atrial Rhythms)

RhythmIrregular
RateVery fast (> 350 bpm) for Atrial, but ventricular rate may be slow, normal or fast
P WaveAbsent – erratic waves are present
PR IntervalAbsent
QRSNormal but may be widened if there are conduction delays
Causes·         High blood pressure.

·         Coronary artery disease.

·         Heart attack.

·         Heart failure.

·         Heart valve disease.

·         Cardiomyopathy.

·         Hyperthyroidism.

·         Lung disease, such as COPD.

·         Having heart surgery

RhythmRegular or irregular
RateFast (250-350 bpm) for Atrial, but ventricular rate is often slower
P WaveNot observable, but saw-toothed flutter waves are present
PR IntervalNot measurable
QRSNormal (0.06-0.10 sec)
Causes·         Hypertension

·         Ischemia

·         Cardiomyopathy

·         Valve diseases

·         Cardiomegaly

·         Hyperthyroidism

·         COPD

·         Hypoxemia

·         Alcohol and most stimulants

RhythmIrregular
RateFast (> 100 bpm)
P WaveOften changing shape and size from beat to beat (at least three differing forms)
PR IntervalVariable
QRSNormal (0.06-0.10 sec)
Causes·         Decompensated chronic lung disease

·         Coronary artery disease

·         Heart failure

·         Valvular heart disease

·         Diabetes

·         Electrolyte Imbalance Especially K+ and Mg+

·         Azotemia especially in renal patients

·         Postoperatively, especially cardiothoracic surgeries

·         Pulmonary embolism

·         Pneumonia

·         Sepsis

·         Methylxanthine toxicity

RhythmIrregular
RateUsually normal but depends on underlying rhythm
P WavePremature, positive and shape is abnormal
PR IntervalNormal or longer
QRS0.10 sec or less
Notes Rarely of any pathological significance. Common causes include caffeine,

Alcohol, stress, fatigue or poor sleep, medication that lists irregular heartbeat as a side effect.

RhythmRegular
RateFast (150-250 bpm)
P WaveMerged with T wave
PR IntervalNormal (0.12 sec)
QRSNormal (.10 sec)
CausesCauses of SVT are many and it is important to look at individual underlying causes. Examples includes

·         Drug toxicity

·         Alcohol

·         Pneumonia

·         COPD

·         Metabolic issues (acidosis, sepsis, etc)

·         Cardiac surgeries

·         Heart defects

 

RhythmMay be irregular
RateNormal (60-100 bpm)
P WaveChanging shape and size from beat to beat (at least three different forms)
PR IntervalVariable
QRSNormal (0.06-0.10 sec)
NotesT wave normal. If heart rate exceeds 100 bpm, then rhythm may be multifocal atrial tachycardia (MAP). P waves may have upright and downward facing morphology depending on the origin of the impulse.
RhythmRegular unless atrial fibrillation present
RateNormal (60-100 bpm)
P WaveNormal
PR IntervalCan be short (<0.12 sec)
QRSUsually wide (> 0.12 sec)
CausesUsually a rare hereditary condition.

 

EKG Rhythms Interpretation: Atrial Ventricular Rhythms.

These rhythms are sometimes called Nodal rhythms or Conduction blocks. Some EKG instructors may combine them with Junctional rhythms classification. These are MUST KNOW for nurses and most clinical healthcare professionals. For critical care nurses preparing for CCRN exams, I highly recommend you listen to Laura Gasparis emphasis on these rhythms.

These rhythms include: –

RhythmRegular
RateThe underlying rate
P WaveNormal
PR IntervalNormal (0.12-0.20 sec)
QRSWide (>0.12 sec)
Notes The most distinct feature of a bundle branch block is the wide QRS.
RhythmRegular
RateThe underlying rate
P WaveNormal
PR IntervalProlonged (>0.20 sec)
QRSNormal (0.06-0.10 sec)
NotesEach QRS is preceded by a P wave only that the PR interval is prolonged >0.20 seconds
RhythmIrregular but with progressively longer PR interval lengthening
RateThe underlying rate
P WaveNormal
PR IntervalProgressively longer until a QRS complex is missed, then cycle repeats
QRSNormal (0.06-0.10 sec)
Notes
RhythmRegular (atrial) and irregular (ventricular)
RateCharacterized by Atrial rate usually faster than ventricular rate (usually slow)
P WaveNormal form, but more P waves than QRS complexes
PR IntervalNormal or prolonged
QRSNormal or wide
Notes
RhythmRegular, but atrial and ventricular rhythms are independent
RateCharacterized by Atrial rate usually normal and faster than ventricular rate
P WaveNormal shape and size, may appear within QRS complexes
PR IntervalAbsent: the atria and ventricles beat independently.
QRSNormal, but wide if junctional escape focus
Notes

 

EKG Rhythms Interpretation: Junctional rhythms:

These are four as below

RhythmRegular
RateNormal (60-100 bpm)
P WavePresent before, during (hidden) or after QRS, if visible it is inverted
PR IntervalNot measurable
QRSNormal (0.06-0.10 sec)
Notes
RhythmRegular
RateSlow (40-60 bpm)
P WavePresent before, during (hidden) or after QRS, if visible it is inverted
PR IntervalNot measurable
QRSNormal (0.06-0.10 sec)
Notes
RhythmRegular
RateFast (100-180 bpm)
P WavePresent before, during (hidden) or after QRS, if visible it is inverted
PR IntervalAbsent or short
QRSNormal (0.06-0.10 sec)
Notes
RhythmRegular with premature beats
RateThe underlying rate
P WavePresent before, during (hidden) or after QRS, if visible it is inverted
PR IntervalAbsent or short
QRSNormal (0.06-0.10 sec)
Notes

 

EKG Rhythms Interpretation: Ventricular Rhythms:

There are 12 ventricular rhythms and all of them are a MUST know for nurses and clinicians. Because these are so important, I have creaed a full lesson, just on ventricular rhythms. These are

  1. Accelerated Idioventricular Rhythm
  2. Idioventricular Rhythm
  3. Premature Ventricular Complex (PVC)
  4. Bigeminy premature ventricular complexes
  5. Trigeminy premature ventricular complexes
  6. Quadrigeminy premature ventricular complexes
  7. Ventricular Tachycardia (V-Tach)
  8. Ventricular Fibrillation (V-Fib)
  9. Monomorphic ventricular tachycardia
  10. Polymorphic ventricular tachycardia
  11. Torsade De Pointes
  12. Asystole

 

RhythmRegular
RateSlow (20-40 bpm)
P WaveAbsent
PR IntervalNot measurable
QRSWide (>0.10 sec), bizarre appearance
Notes
RhythmRegular
Rate50-120 bpm
P WaveAbsent
PR IntervalNot measurable
QRSWide (>0.10 sec), bizarre looking
Notes

 

 

Monomorphic Bigeminy PVC

 

 

 

Trigeminy PVC

 

 

 

 

 

Multifocal PVC

 

 

 

 

 

 

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