1. Practice Alert Dysrhythmia Monitoring
Authors & Reviewers:
Nancy M. Richards, RN, CNS, MSN, CCRN, CCNS
Issued April 2008

2. Lecture Content Skin Preparation Lead Placement
Ventricular Dysrhythmias
QT Intervals
Practice Alert - Dysrhythmia Monitoring

3. Skin Preparation Skin oil and debris can cause noisy signals
Clip excessive hair before placing electrodes
Clean skin with alcohol or washcloth to remove skin oils and/or debris
Practice Alert - Dysrhythmia Monitoring

4. Electrode Placement Limb leads (I,II,III) Placement
Place to decrease muscle artifact during limb movement
Placement
Right Arm (RA) infra-clavicular fossa close to right shoulder
Left Arm (LA) infra-clavicular fossa close to left shoulder
Left Leg (LL) below rib cage on left side of abdomen
Ground (RL) anywhere on torso
Practice Alert - Dysrhythmia Monitoring

5. Electrode Placement Precordial Leads
Dependent on patient’s needs and goals of monitoring
Consider marking electrode location with indelible ink
Ensures electrodes will be placed in same position.
Precordial leads misplaced by 1 ICS can change the QRS morphology
Practice Alert - Dysrhythmia Monitoring

6. Dysrhythmia Monitoring
Lead V1 to distinguish Ventricular Tachycardia (VT) from Supraventricular Tachycardia (SVT) with aberrant conduction
V1 lead of choice for dysrhythmia monitoring
Lead II or III if patient condition indicates need to monitor for atrial dysrhythmias
Practice Alert - Dysrhythmia Monitoring

7. Dysrhythmia Monitoring Lead Placement
V1 (5 lead system)
4th intercostal space (ICS) to the right of the sternum
MCL1 (3 lead system)
Practice Alert - Dysrhythmia Monitoring

8. 3 Lead Electrode Placement
Simple 3-electrode lead system
Electrode placement for MCL1
Only 1 lead can be monitored with a 3 lead system
Practice Alert - Dysrhythmia Monitoring
From Philips Cardiac Monitoring Pocket Card 2002

9. 5 Lead Electrode Placement
Angle of Louis
5 lead systems allow for the recording of any of the six limb leads plus one precordial (V) lead.
Shown lead placement for recording V1 or V6.
5 Lead monitoring systems are recommended over 3 lead systems for monitoring QRS morphology V1 V6
Practice Alert - Dysrhythmia Monitoring
From Philips Cardiac Monitoring Pocket Card 2002

10. QRS Morphology Ventricular Tachycardia
V 1 or MCL1
Monophasic R wave
Notched R wave with taller left peak
Biphasic RS
Biphasic qR
Any of the following in V1 or V2
R > 30ms
Slurred or notched S descent
QRS onset to S nadir >60 ms
V6 or MCL6
Biphasic rS with R:S ratio <1.0
Monophasic Q
Notched QS
Biphasic qR
Intrinsicoid deflection > 70ms
Practice Alert - Dysrhythmia Monitoring

11. QRS Morphology Practice Alert - Dysrhythmia Monitoring
From Philips Cardiac Monitoring Pocket Card 2002
Practice Alert - Dysrhythmia Monitoring

12. QRS Morphology SVT with Aberration
V1 or MCL1
Bimodal rR’ or triphasic rsR’
All of the following in V1 or V2
R < 30 ms or no R
Straight S descent
QRS onset to S nadir < 60 ms and no Q in V6
V6 or MCL6
Triphasic qRs with R:s ratio > 1.0
Intrinsicoid deflection < 50 ms
Practice Alert - Dysrhythmia Monitoring

13. QRS Morphology Practice Alert - Dysrhythmia Monitoring
From Philips Cardiac Monitoring Pocket Card 2002

14. QRS Morphology Not Helpful
V1 or MCL1
R slurred or notched with taller right peak
V6 or MCL6
Monophasic R
Notched R with taller left or right peak
Biphasic Rs with R:S ratio > 1.0
Applies only to tachycardias with a positive waveform in V1
Practice Alert - Dysrhythmia Monitoring

15. QRS Morphology Practice Alert - Dysrhythmia Monitoring
From Philips Cardiac Monitoring Pocket Card 2002

16. Accurate Lead PlacementV1 II V1 II
(B) After lead placement was corrected, another episode of wide QRS complex tachycardia showed the “taller left peak” pattern in lead V1 which is strongly suggestive of ventricular tachycardia (Wellens, et al 1978). Subsequent invasive cardiac electrophysiologic study confirmed the patient had ventricular tachycardia.
(A) Onset of wide QRS complex tachycardia shows a “taller right peak” pattern in lead V1, which is unhelpful in distinguishing between ventricular tachycardia and supraventricular tachycardia with aberrant conduction. Examination of the patient revealed that the V1 electrode was misplaced to the 5th, rather than the 4th intercostal space
Practice Alert - Dysrhythmia Monitoring
Used with permission of Barbara J. Drew RN, PhD

17. QT Interval
Approximate measure of the duration of ventricular repolarization.
Measured from the beginning of the Q wave to the end of the T wave
Varies with heart rate
Lengthens with bradycardia
Shortens with tachycardia
Practice Alert - Dysrhythmia Monitoring

18. QT Interval
Measure from beginning of the QRS complex to the end of the T wave
Practice Alert - Dysrhythmia Monitoring
From Philips Cardiac Monitoring Pocket Card 2002

19. QTc Interval QT interval corrected for heart rate (QTc)
Formula for calculating QTc (Bazett’s formula)
QTc > 0.50 seconds considered dangerously prolonged and is associated with a higher risk of Torsades de Pointes.
Practice Alert - Dysrhythmia Monitoring

20. Measuring the QTc
QT = 0.36
R – R = 0.72
Measure the QT of the second complex used in R – R measurement.
Using Bazett’s formula: QTc = 0.36 / √0.72 = 0.36 / 0.85 = 0.42
QTc = 0.42
Practice Alert - Dysrhythmia Monitoring

21. Torsades de Pointes Polymorphic Ventricular Tachycardia
Precipitated by prolonged QT interval
Not responsive to and may be exacerbated by class Ia and some Ic medications
Practice Alert - Dysrhythmia Monitoring

22. Pause
Arrhythmias associated with prolonged QT interval that place the patient at immediate risk for developing torsades de pointes. ECG characteristics include underlying prolonged QT interval, T wave alternans, polymorphic ventricular premature beats that fall near the T-U portion of repolarization, pause-dependent enhancement of the QT interval (arrow), and non-sustained polymorphic ventricular tachycardia.
Practice Alert - Dysrhythmia Monitoring
Used with permission of Barbara J. Drew RN, PhD

23. Torsades de Pointes
Monitor QT interval for patients identified at high risk:
Patients on medications known to prolong QT interval
Quinidine, procainaminde, disopyraminde, sotalol, dofetilide, ibutilide
For more information see:
Patients who overdose on potentially pro- dysrhythmic medications
New onset bradycardia
Severe hypokalemia or hypomagnesemia
Practice Alert - Dysrhythmia Monitoring

24. Treatment Emergency Long Term IV Magnesium Defibrillation Overdrive
pacing
Long Term
Monitor QTc
interval
Discontinue or
modify drug dose
if QTc interval
increases > 0.50
secs
Practice Alert - Dysrhythmia Monitoring

25. Need Further Assistance?
For more information or further assistance, please contact a clinical practice specialist with the AACN Practice Resource Network.
Phone:
(800)
Practice Alert - Dysrhythmia Monitoring