1. Ventricular Dysrhythmias11
Ventricular Dysrhythmias
Fast & Easy ECGs – A Self-Paced Learning Program Q I A

2. Ventricular Dysrhythmias
Occur when:
The atria, AV junction, or both, are unable to initiate an electrical impulse
There is enhanced automaticity of the ventricular myocardium

3. Ventricular Dysrhythmias
Key features:
Wide (> 0.12 seconds in duration), bizarre QRS complexes
T waves in the opposite direction of the R wave
Absence of P waves

4. Ventricular Dysrhythmias
Premature ventricular complex (PVC)
Ventricular escape complexes or rhythm
Ventricular tachycardia
Ventricular fibrillation
Asystole

5. Ventricular Dysrhythmias
Can be benign or they can be potentially life-threatening (because the ventricles are ultimately responsible for cardiac output)
Instructional point:
A primary concern when approaching ventricular dysrhythmias is what the impact is on cardiac output. The patient must be carefully assessed for the underlying cause such as myocardial ischemia or infarction. I

6. Premature Ventricular Complexes (PVCs)
Early ectopic beats that interrupt the normal rhythm
Originate from an irritable focus in the ventricular conduction system or muscle tissue
Instructional points:
PVCs can occur for no apparent reason in individuals who have healthy hearts and are usually of no significance. The incidence of PVCs increases with age and can occur during exercise or at rest. However, PVCs may also be significant for two reasons. First, they can precipitate more serious dysrhythmias such as ventricular tachycardia or fibrillation. The danger is greater in patients experiencing myocardial ischemia and/or infarction. Second, PVCs can result in decreased cardiac output due to reduced diastolic filling time and a loss of atrial kick.
PVCs may produce a palpable pulse but they may also produce a diminished or nonpalpable pulse (called a nonperfusing PVC). Patients frequently experience the sensation of “skipped beats.” I

7. Premature Ventricular Complexes
Question to ask the students: “What is a compensatory pause?”
Answer: the pause that follows a premature beat is called a compensatory pause if the normal beat following the premature
complex occurs when it was expected. In other words, the period between the complex before and after the premature beat is the
same as two normal R-R intervals.
Instructional point:
PVCs may produce a palpable pulse but they may also produce a diminished or nonpalpable pulse (called a nonperfusing PVC). Patients frequently experience the sensation of “skipped beats.” Q I

8. Premature Ventricular Complexes

9. Premature Ventricular Complexes
PVCs that look the same are called uniform (unifocal)
PVCs that look different from each other are called multiform (multifocal)
Instructional point:
Multiformed PVCs are more concerning because they suggest that the ventricles are more irritable as the early beats are arising from more than one location.
Multifocal I

10. Premature Ventricular Complexes

11. Premature Ventricular Complexes
Two PVCs in a row are called a couplet and indicate extremely irritable ventricles

12. Premature Ventricular Complexes
PVCs that fall between two regular complexes and do not disrupt the normal cardiac cycle are called interpolated PVCs
Question to ask the students: “Will interpolated PVCs have a compensatory pause?”
Answer: No, they do not. Q

13. Premature Ventricular Complexes
PVCs occurring on or near the previous T wave (R-on-T PVCs) may precipitate ventricular tachycardia or fibrillation
Instructional point:
The reason is that a portion of the T wave is vulnerable to electrical stimulation during what is referred to as the relative refractory period. I

14. Idioventricular Rhythm
Slow dysrhythmia (rate of 20 to 40 BPM) with wide QRS complexes that arise from the ventricles
Question to ask the students: “What is the key difference between idioventricular rhythm, accelerated idioventricular rhythm and ventricular tachycardia?”
Answer: The heart rate.
Instructional points:
The decreased cardiac output associated with this dysrhythmia will likely cause the patient to be symptomatic (hypotension, syncope, etc.). Patient assessment is essential because the escape rhythm may be perfusing or nonperfusing.
Idioventricular dysrhythmias are also common during cardiac arrest as they represent the final escape rhythm to be generated in an attempt to perfuse the body. Q I

15. Idioventricular Rhythm

16. Accelerated Idioventricular Rhythm
Idioventricular rhythm that exceeds the inherent rate of the ventricles (60 to 100 BPM)

17. Accelerated Idioventricular Rhythm

18. Ventricular Tachycardia (VT)
Fast dysrhythmia (100 to 250 BPM) that arises from the ventricles
Instructional point:
Clinically, ventricular tachycardia is always significant. Even if the rhythm results in a pulse, it should be considered as potentially unstable, as patients are likely to develop worse rhythms and cardiac arrest. Usually VT indicates significant underlying cardiovascular disease. I

19. Ventricular Tachycardia
Present when there are 3 or more PVCs in a row
May come in bursts of 6 to 10 complexes or may persist (sustained VT)

20. Ventricular Tachycardia

21. Ventricular Tachycardia

22. Ventricular Tachycardia
Can occur with or without pulses
Patient may be stable or unstable
Instructional point:
The rapid rate and concurrent loss of atrial kick associated with VT results in compromised cardiac output and decreased coronary artery and cerebral perfusion. The severity of symptoms varies with the rate of the VT and the presence or absence of underlying myocardial dysfunction. VT may be perfusing or nonperfusing. It may initiate or degenerate into ventricular fibrillation. I

23. Ventricular Tachycardia
Monomorphic - appearance of each QRS complex is similar
Polymorphic - appearance varies considerably from complex to complex

24. Ventricular Fibrillation (VF)
Results from chaotic firing of multiple sites in the ventricles
Causes heart muscle to quiver rather than contract efficiently, producing no effective muscular contraction and no cardiac output
Instructional point:
On the cardiac monitor, ventricular fibrillation appears like a wavy line, totally chaotic, without any logic. I

25. Ventricular Fibrillation

26. Ventricular Fibrillation

27. Ventricular Fibrillation
Death occurs if patient not promptly treated (defibrillation)
Most common cause of prehospital cardiac arrest in adults

28. Asystole Absence of any cardiac activity
Appears as a flat (or nearly flat) line
Complete cessation of cardiac output
Instructional point:
The presence of asystole should always be verified in two leads prior to initiating treatment. I

29. Asystole

30. Asystole

31. Asystole Terminal rhythm Chances of recovery extremely low
Instructional point:
Asystole may be the primary event in cardiac arrest or it may occur in complete heart block when there is no functional escape pacemaker. I

32. Pulseless Electrical Activity (PEA)
Condition that has an organized electrical rhythm on the ECG monitor (which should produce a pulse) but patient is pulseless and apneic
Instructional point:
Sinus rhythm, sinus tachycardia, idioventricular rhythm, or other rhythms may be the electrical activity seen with PEA. I

33. Practice Makes Perfect
Determine the type of dysrhythmia
Answer: Atrial rate absent, Ventricular rate 40 BPM, regular rhythm, absent P waves, QRS complexes are wide and bizarre-looking at 0.20 seconds, PRI is immeasurable, QT 1.12 seconds. Idioventricular rhythm. I

34. Practice Makes Perfect
Determine the type of dysrhythmia
Answer: Atrial rate absent, Ventricular rate 188 BPM, regular rhythm, absent P waves, QRS complexes are wide and bizarre-looking at 0.16 seconds, PRI is immeasurable, QT 0.32 seconds. Ventricular tachycardia. I

35. Practice Makes Perfect
Determine the type of dysrhythmia
Answer: Immeasurable heart rate, totally irregular, absent atrial waveforms, no QRS complexes, PRI is immeasurable, QT is immeasurable. Ventricular fibrillation. I

36. Practice Makes Perfect
Determine the type of dysrhythmia
Answer: Atrial rate absent, Ventricular rate 56 BPM, regular rhythm, absent P waves, QRS complexes are wide and bizarre-looking at 0.16 seconds, PRI is immeasurable, QT seconds. Accelerated idioventricular rhythm. I

37. Practice Makes Perfect
Determine the type of dysrhythmia
Answer: Atrial rate absent, Ventricular rate 188 BPM, regular rhythm, absent P waves, QRS complexes are wide and bizarre looking at 0.24 seconds, PRI is immeasurable, QT is immeasurable. Ventricular tachycardia. I

38. Practice Makes Perfect
Determine the type of dysrhythmia
Answer: Atrial rate 86 BPM, Ventricular rate 86 BPM, frequent irregularity, upright and normal P waves in the underlying rhythm there are no P waves associated with premature beats, normal QRS complexes at 0.08 seconds in underlying rhythm wide, bizarre looking QRS complexes at 0.16 seconds in early beats, PRI seconds in underlying rhythm and absent in the premature beats, QT in the underlying rhythm and 0.40 seconds in the premature beats. Normal sinus rhythm with frequent premature atrial complexes (PACs) (2nd, 5th complexes). I

39. Practice Makes Perfect
Determine the type of dysrhythmia
Answer: Atrial rate 136 BPM, Ventricular rate 136 BPM, patterned irregularity (every fourth beat is a premature beat quadrigeminy), P waves are upright and tall in the underlying rhythm but absent with the premature beats, QRS (more accurately described as QS) complexes
are 0.06 seconds in duration in the underlying rhythm but wide and bizarre in the early beats at 0.20 seconds, PRI seconds in duration for the normal beats but absent with the premature beats, QT 0.28 seconds in the underlying rhythm and 0.36 seconds in the early beats. Sinus rhythm with quadrigeminal premature ventricular complexes (PVCs). I

40. Practice Makes Perfect
Determine the type of dysrhythmia
Answer: Atrial rate 98 BPM, Ventricular rate 98 BPM, frequent irregularity, upright and notched P waves in the underlying rhythm but P waves are absent with the premature beats, QRS complexes are normal at 0.12 seconds in duration in the underlying rhythm but wide and bizarre in the early beats at 0.14 seconds, PRI seconds in duration for the normal beats but absent with the premature beats, QT seconds
in the underlying rhythm and 0.40 seconds in the premature beats. Normal sinus rhythm with frequent multiformed premature ventricular complexes (PVCs) (2nd, 4th, 7th and 9th complexes). I

41. Practice Makes Perfect
Determine the type of dysrhythmia
Answer: Atrial rate 82 BPM, Ventricular rate 82 BPM, occasional irregularity, upright and normal P waves in the underlying rhythm but P waves are absent with the premature beats, QRS complexes are normal at 0.08 seconds in duration in the underlying rhythm but wide and bizarre in the early beats at 0.14 seconds (in the 1st PVC) and 0.20 seconds (in the 1st PVC), PRI 0.12 seconds in duration for the normal beats but absent with the premature beats, QT 0.30 seconds in the underlying rhythm and 0.36 to 0.40 seconds in the premature beats. Normal sinus rhythm with multiformed premature ventricular complexes (PVCs) (2nd and 7th complexes). I

42. Summary
Ventricular dysrhythmias occur when the atria, AV junction, or both, are unable to initiate an electrical impulse or when there is enhanced excitability of the ventricular myocardium.
A key feature of ventricular dysrhythmias are wide (greater than 0.12 seconds in duration), bizarre QRS complexes that have T waves in the opposite direction of the R wave and an absence of P waves.
Ventricular dysrhythmias include: premature ventricular contraction (PVC), ventricular escape complexes or rhythm, ventricular tachycardia, ventricular fibrillation, and asystole.

43. Summary
Premature ventricular complexes are early ectopic beats that interrupt the normal rhythm and originate from an irritable focus in the ventricular conduction system or muscle tissue.
Idioventricular rhythm is a slow dysrhythmia with wide QRS complexes that arise from the ventricles at a rate of 20 to 40 beats per minute.

44. Summary
Ventricular tachycardia is a fast dysrhythmia, between 100 to 250 beats per minute that arises from the ventricles.
It is said to be present when there are three or more PVCs in a row.
It can occur with or without pulses, and the patient may be stable or unstable with this rhythm.

45. Summary
VT may be monomorphic, where the appearance of each QRS complex is similar, or polymorphic, where the appearance varies considerably from complex to complex.
Ventricular fibrillation (VF) results from chaotic firing of multiple sites in the ventricles causing the heart muscle to quiver rather than contracting efficiently, producing an absence of effective muscular contraction and cardiac output.
Asystole is the absence of any cardiac activity. It appears as a flat (or nearly flat) line on the monitor screen and produces a complete cessation of cardiac output.

46. Summary
Pulseless electrical activity (PEA) is a condition in which there is an organized electrical rhythm on the ECG monitor (which should produce a pulse) but the patient is pulseless and apneic.
Sinus rhythm, sinus tachycardia, idioventricular rhythm, or other rhythms may be the electrical activity seen with PEA.