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….

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
     • 1^st Degree Atrio-Ventricular Block
     • 2^nd Degree Atrio-Ventricular Block type 1 (Wincheback)
     • 2^nd Degree Atrio-Ventricular Block type 2
     • 3^rd 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:

• Sinus rhythms – Originates from Sino-Atria Node
• Atrial rhythms – Originates from the Atrium
• Atrioventricular rhythms – Originates from Atrioventricular Node (AV-Node)
• Junctional rhythms – May originate from either SA or AV nodes
• Ventricular Rhythms – Originates from ventricles
• Pace maker rhythms – Originates from artificial pace maker devices.

Rhythms originating from Sinoatrial Node:

• Normal Sinus Rhythm (NSR)

  The normal sinus rhythm (NSR) denotes a specific type of sinus rhythm where all other measurements on the ECG also fall within designated normal limits, giving rise to the characteristic appearance of the ECG.

  Normal Sinus Rhythm Characteristics

  Rhythm	Regular
  Rate	Normal (60-100 bpm)
  P Wave	Normal (positive & precedes each QRS)
  PR Interval	Normal (0.12-0.20 sec)
  QRS	Normal (0.06-0.10 sec)
  Notes

  

  

• Sinoatrial Exit Block:

  In an SA block, the electrical impulse is delayed or blocked on the way to the atria, thus delaying the atrial beat
  

  Characteristics of Sinoatrial Block

  Rhythm	Irregular when SA block occurs
  Rate	Normal or slow
  P wave	Normal
  PR Interval	Normal (0.12-0.20 sec)
  QRS	Normal (0.06-0.10 sec)
  Notes/Causes	Pause time is an integer multiple of the P-P Interval

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

Sinus Arrhythmia

• Sinus Bradycardia. A regular heart rhythm originating from SA-Node but slower than 60 beats a minute.

• Sinus Tachycardia. Asinus rhythm is a regular  elevated rate of impulses greater than 100 beats/min (bpm) in an average adult.

EKG Rhythms originating from Atrium. (Atrial Rhythms)

• Atrial Fibrillation (A-Fib). A quivering irregular heart rhythm (R-R intervals are irregular) with no predictable pattern and no desirable P wave. It is said to be “Irregulary Irregular with no desirable P wave.

• Atrial Flutter. An abnormal heart rate, or arrhythmia that occurs when the atrium beat too fast, approximately 350 beats a minute and the ventricular rate is much slower.

• Multifocal Atrial Tachycardia: Multifocal atrial tachycardia (MAT) is a cardiac arrhythmia caused by multiple sites of competing atrial activity. It is characterized by an irregular atrial rate greater than 100 beats per minute (bpm). Atrial activity is well organized, with at least 3 morphologically distinct P waves, irregular P-P intervals, and an isoelectric baseline between the P waves. Edward Burn’s Blog has good explanation.

• Premature Atrial Complex (PAC): A premature beat arising from an ectopic focus within the atria. PAC’s occur when a beat occurs early in the heart cycle than expected. One of the most common symptoms of APCs is heart palpitations or unusual awareness of your heartbeats.

• Supraventricular Tachycardia (SVT): By definition, it is a rapid heart rate, usually above 150 beats per minute with impulses originating from the ventricles. For the purpose of this lesson, I will not get into the details about different types of SVT. It may not be of much use to a nurse.

• Wandering Atrial Pacemaker (WAP): A wandering atrial pacemaker is an atrial arrhythmia that occurs when the natural cardiac pacemaker site shifts between the sinoatrial node (SA node), the atria, and/or the atrioventricular node (AV node). The name defines what is happening and paying close attention to the morphology of the P wave will make it easier to recognize the rhythm.

• Wolff-Parkinson-White Syndrome: Wolff-Parkinson-White (WPW) syndrome is a condition in which there is an extra electrical pathway in the heart.

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: –

• Bundle Branch Blocks: Bundle branch block is a condition in which there’s a delay or obstruction along the pathway that electrical impulses travel to make your heart beat. The delay or blockage may occur on the right or left bundles causing right or left bundle branch block

• 1^st Degree Heart Block: First-degree atrioventricular (AV) block, or first-degree heart block, is defined as prolongation of the PR interval to more than 200 msec.

• Second Degree AV Block – Type 1 (Winchebach or Mobitz 1): Mobitz 1 heart block is characterized by progressive prolongation of the PR interval on consecutive beats followed by a blocked P wave (i.e., a ‘dropped’ QRS complex). After the dropped QRS complex, the PR interval resets and the cycle repeats again.

• Second Degree Heart Block Type II: In Type II (Mobitz) AV block the PR intervals are constant until a nonconducted P wave occurs. There must be two consecutive constant PR intervals to diagnose Type II AV block. The RR interval of the pause is equal to the two preceding RR intervals.

• Third Degree Heart Block AKA – Complete heart Block is a disorder of the cardiac conduction system where there is no conduction through the atrioventricular node. Therefore, complete dissociation of the atrial and ventricular activity exists. The P waves and QRS has no correlation. Since the QRS is originating from the ventricular impulses, the rate is usually less than 40 beats a minute.

EKG Rhythms Interpretation: Junctional rhythms:

These are four as below

• Accelerated Junctional Rhythm: (AJR) occurs when the rate of an AV junctional pacemaker exceeds that of the sinus node.

• Junctional Escape Rhythm: A junctional escape beat is a delayed heartbeat originating not from the atrium but from an ectopic focus somewhere in the AV junction. It occurs when the rate of depolarization of the sinoatrial node falls below the rate of the atrioventricular node. This dysrhythmia also may occur when the electrical impulses from the SA node fail to reach the AV node because of SA or AV block.

• Junctional Tachycardia: It is a form of supraventricular tachycardia associated with the generation of impulses in a focus in the region of the atrioventricular node due to an A-V disassociation. Since the intrinsic rate of ventricles is 40-60 beats per minute, Junctional tachycardia has a rate above 60 beats a minute.

• Premature Junctional Complex (PJC): Premature junctional complexes (PJCs) are premature depolarizations from the AV node or the proximal portion of the His-Purkinje system

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

• Idioventricular Rhythm (IDVR)
  Ectopic ventricular rhythms occur commonly in acute myocardial infarction. The rate is usually 20-40 bpm. If the rate is >40 bpm, it is called accelerated idioventricular rhythm. The rate of 20-40 is the “intrinsic automaticity” of the ventricular myocardium. It can be regarded as a “backup plan” or “redundancy” built into the body.

• Accelerated Idioventricular Rhythm: Defined as an enhanced ectopic ventricular rhythm with at least 3 consecutive ventricular beats, which is faster than normal intrinsic ventricular escape rhythm (≤40 bpm), but slower than ventricular tachycardia. AIVR results when the rate of an ectopic ventricular pacemaker exceeds that of the sinus node often associated with increased vagal tone and decreased sympathetic tone.

• Premature Ventricular Complex (PVC): A premature beat arising from a single or multiple  ectopic focus within the ventricle.
  

  Rhythm	Irregular
  Rate	The underlying rate
  P Wave	Absent
  PR Interval	Not measurable
  QRS	Wide (> 0.10 sec), bizarre appearance
  Notes	Two PVCs together are termed a couplet

  

• Ventricular Tachycardia (V-Tach)