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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Accurate Lead Placement V1 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

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

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

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

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

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

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

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: http://www.arizonacert.org/medical-pros/drug-lists/printable-drug-list.cfm Patients who overdose on potentially pro- dysrhythmic medications New onset bradycardia Severe hypokalemia or hypomagnesemia Practice Alert - Dysrhythmia Monitoring

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

Need Further Assistance? For more information or further assistance, please contact a clinical practice specialist with the AACN Practice Resource Network. Email: practice@aacn.org Phone: (800) 394-5995 Practice Alert - Dysrhythmia Monitoring