1. Dysrhythmia & ST Segment Monitoring
Issued May 2005

2. Lecture Content Skin Preparation Lead Placement
Ventricular Dysrhythmias
QT Intervals
ST Segment Monitoring
Presentation relies on research based guidelines from national groups, governmental agencies or expert groups.
Dysrhythmia/ST Monitoring Practice Alert

3. Skin Preparation Clinically significant ST segment changes > 1mm
Skin oil and debris can cause noisy signals
Shave excessive hair before placing electrodes
Clean skin with alcohol or washcloth to remove skin oils and/or debris
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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)
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5. Electrode Placement Precordial Leads
Dependent on patient’s needs and goals of monitoring
Mark electrode location with indelible ink
Ensures electrodes can be replace in same position.
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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
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7. Dysrhythmia Monitoring Lead Placement
V1 (5 lead system)
4th intercostal space (ICS) to the right of the sternum
MCL1 (3 lead system)
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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
From Philips Cardiac Monitoring
Pocket Card 2002
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9. 5 Lead Electrode Placement
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
From Philips Cardiac Monitoring
Pocket Card 2002
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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
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11. QRS Morphology From Philips Cardiac Monitoring Pocket Card 2002
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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
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13. QRS Morphology From Philips Cardiac Monitoring Pocket Card 2002
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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
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15. QRS Morphology From Philips Cardiac Monitoring Pocket Card 2002
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16. Accurate Lead Placement
Precordial leads misplaced by 1 ICS can change the QRS morphology
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17. Accurate Lead PlacementV1 II
(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
Used with permission of Barbara Drew RN, PhD
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18. Accurate Lead PlacementV1 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.
Used with permission of Barbara Drew RN, PhD
Dysrhythmia/ST Monitoring Practice Alert

19. QT Interval
Indirect measure of the time between ventricular repolarization and depolarization.
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
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20. QT Interval
Measure from beginning of the QRS complex to the end of the T wave
QT interval < 0.50 sec.
From Philips Cardiac Monitoring
Pocket Card 2002
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21. QTc Interval QT interval corrected for heart rate
Formula for calculating QTc
QTc = QT + square root of R to R interval
QTc < 0.50 seconds
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22. Torsades de Pointe Polymorphic Ventricular Tachycardia
Precipitated by prolonged QT interval
Not responsive to and may be exacerbated by class Ia and some Ic medications
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23. 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.
Used with permission of Barbara Drew RN, PhD
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24. Torsades de Pointe
Monitor QT interval for patients identified at high risk
Patients on medications know to prolong QT interval
Quinidine, procainaminde, disopyraminde, sotalol, dofetilide, ibutilide
More information see:
Patients who overdose on potentially prodysrhythmic medications
New onset bradycardia
Severe hypokalemia or hypomagnesemia
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25. Treatment Emergency Long Term IV Magnesium Defibrillation
Overdrive pacing
Long Term
Monitor QT interval
Discontinue or modify drug dose if QT interval increases > 0.50 secs
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26. ST Segment Monitoring Lead Selection
Lead that best defines the patient’s “ST fingerprint”
The pattern of ST segment elevations and depressions that is unique to the patient based on the anatomic site of coronary occlusion.
Can be used to diagnose reocclusion of the affected vessel
Acute Coronary Artery Syndrome
Leads III and V3
Early VAP (within 96 hours) is associated with non-multi-antibiotic-resistant organisms:
E coli
Klebsiella
Proteus
Streptococcus pneumoniae
Hemophylus influenza
Oxacillin sensitive Staphlococcus aureus
Late VAP associated with antibiotic-resistant organisms:
Pseudomonas aeruginosa
Oxacillin resistance Staphaerius and Acinetobacter
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27. High Risk Patients Early phase of acute coronary syndrome
STEMI, NonSTEMI or Unstable Angina
Present with chest pain or angina-
equivalent symptoms
Non-urgent PCI with suboptimal
angiographic results
Variant angina due to coronary
vasospasm
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28. LEAD PLACEMENT Place patient in supine position
Head of bed no more than 450 angle
Mark location of lead placement with indelible ink
All these CDC recommendations are at level IA:
Use a continuous subglottic suction ET tube for all intubations expected to be > 24 hours.
Keep the HOB elevated to at least 30 degrees unless medically contraindicated.
Vent circuit - do not change routinely; change when visibly soiled / malfunctioning. Periodically drain / discard condensate in tubing – away from patient
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29. Alarm Parameters
Set alarm parameters 1-2 mm above and below the patient’s baseline
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30. Measuring the ST Segment
J Point:
The junction of the QRS complex with the ST segment
J point
Measure ST segment changes 60 ms beyond
the J point
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31. Need Further Assistance?
For more information or further assistance, please contact a clinical practice specialist with the AACN Practice Resource Network.
Phone:
(800) , x217
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