Kate Martin CNE April 2009

Kate Martin CNE  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 Although chest pain is a real-time indicator of ischemia, up to 80% to 90% of ischemia is "silent" or "concealed”

Kate Martin CNE 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 Although the accuracy of continuous ST monitoring has improved with technology the diagnostic relevance of ST changes remains dependant on several factors ST segment changes may be an indication for a 12 lead EKG

Kate Martin CNE On Admission Ensure skin is properly prepped Ensure leads are in proper position Record a baseline ST strip

Kate Martin CNE 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 monitor Choose the leads which monitor the area of the heart most at risk

Kate Martin CNE

Leads I & V 1-4  LAD  LM

Kate Martin CNE Leads avR, avL, & V 5-6  Circumflex

Kate Martin CNE Leads II, III, & avF  RCA  Circumflex

Kate Martin CNE Leads I & V 1-4  Mirror Image  Posterior Artery

Kate Martin CNE 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 Hypokalemia  ST depression Hyperkalemia  Peaked T waves Hypermagnesemia  ST depression Hyperthyroidism  ST elevation with T wave inversion in inferior leads

Kate Martin CNE Digitalis  ST depression  Shortened QT interval Amiodarone  Lengthened QT interval

Kate Martin CNE Pericarditis  ST elevation Hypothermia  ST depression Pulmonary Infarction  Depressed ST segments and inverted T waves in V 1 – 3

Kate Martin CNE Bundle Branch Blocks  ST segment shifts Paced Rhythm  ST segments non diagnostic

Kate Martin CNE Is patient experiencing angina symptoms?  Follow ACS protocol Is patient hemodynamically unstable  Stabilize

Kate Martin CNE

A number of drugs are known to prolong the QT interval and include all of the antiarrhythmics

Kate Martin CNE QT prolongation can indicate a risk of severe arrhythmias, torsades de pointes, and sudden cardiac death.

Kate Martin CNE The QT has an inverse relationship to HR. QT = QTc at a HR of 60 bpm only Heart rate corrected QT interval is abbreviated as QTc Normal QTc is < 460 ms

Kate Martin CNE

“Cannot Analyze QT” INOP message: Flat T, Atrial Fib/Flutter Prominent U Waves Highly 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 Leeper, B. Continuous ST-segment monitoring. AACN Clinical Issues (2): American Association Of Critical Care Nurses St Segment Monitoring Practice Alert Critical 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