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Kate Martin CNE April 2009. Beyond Arrhythmias ST & QT Segment Monitoring. Monitoring Practice International Guidelines. Chest pain that prompts a visit to the emergency department, Post cardiac surgery Patients at risk for postoperative cardiac complications after non-cardiac surgery. - PowerPoint PPT Presentation
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Kate Martin CNE
Beyond ArrhythmiasST & QT Segment Monitoring
Kate Martin CNEApril 2009
Kate Martin CNE
Monitoring Practice International Guidelines
Chest pain that prompts a visit to the emergency department,
Post cardiac surgery Patients at risk for postoperative cardiac
complications after non-cardiac surgery.
Kate Martin CNE
Angina
Although chest pain is a real-time indicator of ischemia, up to 80% to 90% of ischemia is "silent" or "concealed”
Kate Martin CNE
Diagnostic Testing
12-lead (ECG), measurement of serum markers of injury, and cardiac catheterization, provide only a static "snapshot" of the dynamic process of ongoing ischemia.
Kate Martin CNE
Diagnostic Relevance
Although the accuracy of continuous ST monitoring has improved with technology the diagnostic relevance of ST changes remains dependant on several factorsST segment changes may be an indication for a 12 lead EKG
Kate Martin CNE
Establishing ST Monitoring
On Admission Ensure skin is properly preppedEnsure leads are in proper positionRecord a baseline ST strip
Kate Martin CNE
Choosing Your Leads
Just like with a 12 lead EKG, lead placement should be accurate.The Phillips monitor can monitor ST segments on up to six leads on a telemetry unit and all 12 leads on a hardwire monitorChoose the leads which monitor the area of the heart most at risk
Kate Martin CNE
12 Lead Limb Lead Placement
Kate Martin CNE
12 Lead Precordial Lead Placement
Kate Martin CNE
12 Lead View
Kate Martin CNE
12 Lead EKG
Kate Martin CNE
Standard Monitor Lead Placement
Kate Martin CNE
EASI Lead Placement
Kate Martin CNE
EASI View
Kate Martin CNE
Continuous ST Monitoring
Kate Martin CNE
ST Segment Map
Kate Martin CNE
The Coronary Arteries
Kate Martin CNE
Anterior Leads
Leads I & V1-4 LAD LM
Kate Martin CNE
Lateral Leads
Leads avR, avL, & V5-6 Circumflex
Kate Martin CNE
Inferior Leads
Leads II, III, & avF RCA Circumflex
Kate Martin CNE
Posterior Leads
Leads I & V1-4 Mirror Image Posterior Artery
Kate Martin CNE
The J Point
The ST segment begins at the point where the QRS ends (J-point). Diagnostic criteria of ST segment changes have been defined to be measured at 60 ms after the J-point (1.5 small squares/.06sec)
Kate Martin CNE
Metabolic Abnormalities Producing ST Changes
Hypokalemia ST depressionHyperkalemia Peaked T wavesHypermagnesemia
ST depressionHyperthyroidism ST elevation with
T wave inversion in inferior leads
Kate Martin CNE
Medications Producing ST Changes
Digitalis ST depression Shortened QT interval
Amiodarone Lengthened QT interval
Kate Martin CNE
Other Factors Producing ST ChangesPericarditis
ST elevationHypothermia
ST depressionPulmonary Infarction
Depressed ST segments and inverted T waves in V 1 – 3
Kate Martin CNE
Effect of ArrhythmiasBundle Branch Blocks
ST segment shiftsPaced Rhythm
ST segments non diagnostic
Kate Martin CNE
Response to change in ST Segment
Is patient experiencing angina symptoms?
Follow ACS protocolIs patient hemodynamically unstable
Stabilize
Kate Martin CNE
United Hospital’s Nassett Heart Center, St Paul, Minnesota
Practice Standard ProtocolFor all patients receiving cardiac monitoring, the default for continuous ST segment monitoring is ‘on’ with alarm set for 2mm change (depression or elevation_ from baseline.Nurse turns ‘off’ for patients with the following• Intraventricular conduction defect
(either left or right bundle branch block)• Pacemakers (where pacing is the
dominant rhythm)• Confirmed Pericarditis or
myocardial contusion• ST segment ‘sagging’ due to
Digoxin
Assessment by RN after ST alarms will include first verifying:• Patient is supine (<45o backrest
elevation)• Leads are correctly placed on
clean dry skinIf the patient has a 2-mm ST change sustained for 15 minutes (with or without symptoms)• Nurse will obtain a 12-lead
electrocardiogram to confirm the ST segment changes (standing order) and call a physician
Kate Martin CNE
The QT Interval
Kate Martin CNE
Pharmacology and the QT Interval
A number of drugs are known to prolong the QT interval and include all of the antiarrhythmics
Kate Martin CNE
Importance of QT monitoring QT prolongation can indicate a risk of
severe arrhythmias, torsades de pointes, and sudden cardiac death.
Kate Martin CNE
What is a QTc?
The QT has an inverse relationship to HR.
QT = QTc at a HR of 60 bpm onlyHeart rate corrected QT interval is
abbreviated as QTcNormal QTc is < 460 ms
Kate Martin CNE
QT Monitoring
Kate Martin CNE
Setting Alarms
Kate Martin CNE
QT Measurement Limitations
“Cannot Analyze QT” INOP message:Flat T, Atrial Fib/FlutterProminent U WavesHighly variable QRS-T waveforms over 10
minutes duration
Clinical Verification:Widened QRS (Paced rhythm, bigeminal
rhythm)High heart rates > 150 due to P waves being
too close to T waves.
Kate Martin CNE
Sources
Leeper, B. Continuous ST-segment monitoring. AACN Clinical Issues 2003. 14(2): 145-154. American Association Of Critical Care Nurses St Segment Monitoring Practice AlertCritical Care Nurse. 2005; Clinical Usefulness of the EASI 12-Lead Continuous Electrocardiographic Monitoring System; Mary Jahrsdoerfer, RN, MHA.,Karen Giuliano, RN, PhD., Dean Stephens, RN, MS