Ventricular Dysrhythmias

Learning Goals:

9.1 Describe the various ventricular dysrhythmias.
9.2 Analyze PVCs and their effect on the patient, including basic patient care
and treatment.
9.3 Analyze agonal rhythm and its effect on the patient, including basic patient
care and treatment.
9.4 Analyze idioventricular rhythm and its effect on the patient, including basic
patient care and treatment.
9.5 Analyze accelerated idioventricular rhythm and its effect on the patient,
including basic patient care and treatment.
9.6 Analyze ventricular tachycardia and its effect on the patient, including
basic patient care and treatment.
9.7 Analyze ventricular fibrillation and its effect on the patient, including basic
patient care and treatment.
9.8 Analyze asystole and its effect on the patient, including basic patient care
and treatment.

Ventricular Dysrhythmia General Notes:


  • Ventricular Pacemaker cells are in the Purkinje Fibers

  • The last pacemaker of the 3 are the cells in the heart

  • Rate of automaticity is 20-40bpm (Pacemaker Cells)

  • Current travels from cell to cell (Instead of the “highway” or bundle branches)

  • Wide QRS


Reasons for Ventricular Rhythms

  • Higher pacemakers fail, others will take over either AV or heart Cells

  • All atrial impulses are completely blocked from entering the ventricles, which is why they take cell to cell travel instead of SA or AV conduction

  • All ventricular complexes & rhythms share a missing P wave & wide/ bizzare QRS complexes that measure 0.12 secs or greater


PVC 5 steps:

Rhythm: P-P interval is regular; R-R intervals are regular with exception of early QRS complexes; early complex has a full compensatory pause

Rate: Atrial and ventricular rates are the same for the underlying rhythm; PVCs make ventricular rhythm faster than normal rhythm

P wave: Assumes shape of underlying rhythm; P waves are not present on PVCs

PR Interval: Follows underlying rhythm; P wave not present in PVCs

QRS: typically 0.06-0.10; depending on underlying rhythm; PVC typically 0.12 secs or greater & bizarre; T wave occurs in opposite direction of ventricular depolarization




Dysrhythmias & Types of PVCs:

  • Bigeminy: A pattern of PVCs in which every other Complex is a PVC

  • Trigeminy: a pattern of PVCs in which every 3rd complex is a PVC

  • Quadgeminy: every 4th complex is a PVC

  • coupling: Two PVCs that occur back to back

  • Freqnt PVCs: Six or more PVCs per minuteue

  • Interpolated PVC: PVC that occurs during the normal R-R Interval without interrupting the underlying rhythm


  • Multifocal PVC: Varied shapes and forms of the PVCs, suggesting more than one irritable focus

  • Occasional PVC: Less than 6 PVCs per minute

  • Paroxysmal Event: A witnessed change in any cardiac rhythm, including starting, stopping or both; for ex- sinus rhythm to SVT or Ventricular Tach to Ventricular fibrillation

  • Premature Ventricular Complex (PVC): An ectopic impulse originating in either ventricle that occurs too early in the cycle

  • R on T PVC: PVC that occurs on the downslope of the T wave or the vulnerable period of the relative ventricular refractory period

  • Run of Ventricular Tachycardia: Three or more PVCs occuring in a row at a rate greater than 100bpm

  • Salvo: another term for ventricular Tachycardia; a rapid sequence of abnormal heartbeats, typically 3-30 consecutive beats originating in the ventricles, known as a PVC

  • Triplet PVCs: another name for ventricular tachycardia

  • Unifocal PVC: Early Complexes that have a similar shape, suggesting only one irritable focus present

  • Torsades De Pointes (SVT or VT): Depolarization impulses move from one ventricle to the other, resulting in a “twisted ribbon” or “bow tie” appearance on the ECG tracing; occurs due to electrolyte deficiencies; treatment includes magnesium sulfate


Rhythm: P-P interval usually not identifiable; R-R interval usually regular, can be slightly irregular at times.

Rate: Ventricular rate- 100‒200 beats per minute; Atrial rate- Cannot be determined

P wave: Absent

PR interval: Cannot be determined

QRS: Duration greater than 0.12 second; Wide, bizarre appearance; T wave in opposite direction (usually down) from QRS complex


Lost atrial kick and decreased ventricular filling time result in decreased cardiac output.

Approximately 50% of patients become unconscious immediately.

Notify licensed practitioner immediately.

Save rhythm strips in medical record to document rhythm changes.



  • Agonal Rhythm: Occurs when all the pacemakers of the heart have failed; the heart is dying; ventricular rate is less than 20bpm


Rhythm: There is no P-P interval; R-R may or may not be regular

Rate: Ventricular- Less than 20bpm; Atrial- cannot be determined

P wave: No P wave is present

QRS: 0.12 secs or greater; wide, bizarre appearance


Profound loss of cardiac output.

Patient will be unconscious.

Notify health care practitioner immediately.

This is a medical emergency; BLS and ACLS interventions will be initiated.

ECG strips must be saved and put in medical record.


**This is a medical Emergency**

  • Idioventricular Rhythm: Impulse created by the ventricular pacemaker; SA node & junctional Pacemaker failed to initiate impulse; presents with classic QRS, slow ventricular rate; & no P waves; 20-40bpm


Rhythm: R-R interval is regular; P-P interval cannot be determined

Rate: Ventricular- 20-40bpm; Atrial- Cannot be determined

P wave morphology: No P wave is present.

PR interval: Cannot be measured

QRS duration and morphology: 0.12 seconds or greater; Wide, bizarre appearance



**This is a medical Emergency**

Profound loss of cardiac output

The patient will likely be unconscious.

Notify health care practitioner immediately.

This is a medical emergency.

Likely to require medication and/or pacing.

ECG strips must be saved and put in medical record.



  • Accelerated Idioventricular Rhythm: impulse created by the ventricular pacemaker due to SA and AV node failure; The heart rate is faster than an idioventricular rhythm; QRS is wide & bizarre; P waves are absent; 40-100bpm


Rhythm: R-R interval is regular; P-P interval cannot be determined

Rate: Ventricular- 40‒100 bpm; Atrial- Cannot be determined

P wave: No P wave is present

PR Interval: Cannot be identified

QRS: 0.12 second or greater; Wide, bizarre appearance


Decrease in cardiac output due to slow ventricular rate and loss of atrial kick.

Patient may be unconscious.

Notify health care practitioner immediately.

May require medication and/or pacing.

ECG strips must be saved and put in medical record.Ventri

  • ventrcular Tachycardia: Occurs when there is 3 or more PVCs in a row & the HR is over 100bpm; Ventricles are continously contracting & relaxing with no period of repolarization.


Rhythm: P-P interval usually not identifiable; R-R interval usually regular, can be slightly irregular at times.

Rate: Ventricular rate- 100‒200 beats per minute; Atrial rate- Cannot be determined

P wave: Absent

PR interval: Cannot be determined

QRS: Duration greater than 0.12 second; Wide, bizarre appearance; T wave in opposite direction (usually down) from QRS complex

Lost atrial kick and decreased ventricular filling time result in decreased cardiac output.

Approximately 50% of patients become unconscious immediately.

Notify licensed practitioner immediately.

Save rhythm strips in medical record to document rhythm changes.

  • Ventricular Fibrillation: chaotic, asynchronous electrical activity within ventricular tissue; Ventricle walls quiver, preventing ejection of blood; No cardiac output


Rhythm: P-P and R-R intervals cannot be determined because neither P waves nor R waves are present.

Rate: Neither the atrial nor the ventricular rate can be determined.

P wave morphology: No P waves are present.

PR interval: There is no PR interval.

QRS duration and morphology: Cannot be determined.


Always check the patient first.

In true ventricular fibrillation: ***Medical Emergency***

Patient is unconscious, apneic, and pulseless

True emergency situation

Initiate Code Blue and begin CPR/ACLS procedures immediately.

  • Asystole: Absence of ventricular activity and depolarization; no electrical activity is present in the myocardium; straight line/ flatline; Always confirm asystole in at least two different leads to rule out “fine” ventricular fibrillation.


Rhythm: No waveforms are present.

Rate: No atrial or ventricular rates are present.

P wave morphology: No P waves are present.

PR interval: Cannot be measured

QRS duration and morphology: Not measurable


Situation is life-threatening.

Patient will be unconsciousness and apneic.

Patient is in cardiac arrest; initiate emergency procedures.

Always a Code Blue situation.