Challenging Cardiac Arrhythmias:A Case-based Approach

Mary G Carey, PhD, RN, CNS, FAHAAssociate Director, Clinical Nursing Research Center, Strong Memorial Hospital

Associate Professor, School of NursingVermont sponsored New England Assembly of Nurse Anesthetists Fall Workshop

October 26, 2013© 2013 Mary G. Carey, PhD, RN, CNS, FAHA

Recommendations vary regarding initial competency

It is unknown what is neccessray to maintain competency

Major interpretation errors are common (4% to 33%) but adverse patient outcomes resulting from these errors are rare (<1%).

Computer analyses of ECGs are useful adjuncts but should not replace a qualified clinician in making patient decisions.

Evidence-Based Knowledge

The best way to avoid errors in interpreting ECGs, is to analyze an ECG systematically, step by step.

• Rate?• Regularity?• P waves?• PR interval?• QRS duration?

Calculate heart rate Regular or irregular Normal or absent

Narrow or wideFixed or variable

Interpretation?

The ECG PaperHorizontally (measure of time)

One small box - 0.04 seconds One large box - 0.20 seconds

Vertically (amplitude) One little box 1mm One large box 5 mm or 0.5 mV

Calculating Heart Rate

Option 1 Count the # of R waves in a 6 second rhythm

strip, then multiply by 10. Best used with irregular rhythms

Interpretation? 9 x 10 = 90 bpm

3 sec

3 sec

Option 2 Find a R wave that lands on a bold line. Count the # of large boxes to the next R wave. Best used with regular rhythms

R wave

Calculating Heart Rate

Marriott's Practical ElectrocardiographyGS Wagner & HJL Marriott

0.12-0.20 (3-5 boxes)

<0.12seconds (3 boxes)

Is the PR interval fixed or variable?

Fixed

Does every P wave cause a

QRS complex?

1st degree

Are some QRS complexes dropped?

2nd degree,Type II

Variable

Is the PR interval lengthening?

2nd degree, Type I

Is the PR interval random?

3rd degree

Flow Chart for Heart Blocks

Rhythm

60 bpm• Rate?• Regularity? Regular

Normal

Narrow

• P waves?• PR interval? Fixed but too long • QRS duration?

Interpretation? 1st Degree AV Block

Rhythm

50 with 6 sec strip30 with R toR• Rate?

• Regularity? Irregularnl, but 4th no QRS

Narrow

• P waves?• PR interval? Lengthens• QRS duration?

Interpretation? 2nd Degree AV Block, Type I

Wenckebach

Rhythm

40 bpm• Rate?• Regularity? Regular

Normal, some blocked

Narrow

• P waves?• PR interval? Fixed• QRS duration?

Interpretation? 2nd Degree AV Block, Type II

Rhythm

40 bpm• Rate?• Regularity? Regular

No relation to QRS

Wide

• P waves?• PR interval? None • QRS duration?

Interpretation? 3rd Degree AV Blockwith a Idioventricular Escape Rhythm

95 bpm• Rate?• Regularity? Irregular

Intermittent

Narrow & wide

• P waves?• PR interval? Fixed, nl or absent

• QRS duration?

Interpretation? Bigeminy with a ventricular couplet

24 year old trauma patient (lead I)

Bradycardia with early repolarization and premature junctional contractions (PJCs)

• Rate?

• Regularity?

• P waves?

• PR interval?

• QRS duration?

37-54 bpm

Regular, irregular

Normal, inverted

NarrowFixed

Tri- athlete

12 Lead ECG Limb leads Precordial leadsRhythm strip

Anatomic Groups

72 yo male, routine resting 12-lead ECG

Sinus rhythm at 80 bpm with a left bundle branch block (LBBB)

Pathological Q waves 0.04s wide (one little box) and ¼ of R amplitude

Fragmented QRS complexes (fQRS)

• Improved sensitivity and negative predictive value (Das, et al. 2006)

• Associated with adverse cardiac events (Pietrasiket al. 2007)

• Regional fQRS patterns predict regional infarction in the absence of Q waves (Mahenthiran, et al. 2007)

I

aVR

II

III

aVF

ECG Methodology

V1

V3

V5

V4

V6

V2

Characteristics of the 12-lead HolterECG in Professional Firefighters

National Institutes of Health Grants R21 NR011077

Mary G. Carey RN, CNS, PhDAssociate ProfessorThe State University of New YorkUniversity at Buffalo September 29, 2010

Sinus at 90bpm

Sinus Rhythm 90bpm

Recognizing ST Deviation

Normal Ischemia, ST depression Injury, ST elevation

Single Lead Monitoring Lead II

Interpretation? Sinus Rhythm with baseline wander and artifact

60 bpm• Rate?• Regularity? Regular

Normal

Narrow

• P waves?• PR interval? Fixed• QRS duration?

Injury is regional, not global

Interpretation? Sinus Rhythm at 60 bpm an acute anterior lateral wall infarction

Challenging Cardiac Arrhythmias:A Case-based Approach

Mary G Carey, PhD, RN, CNS, FAHAAssociate Director, Clinical Nursing Research Center, Strong Memorial Hospital

Associate Professor, School of NursingVermont sponsored New England Assembly of Nurse Anesthetists Fall Workshop

October 26, 2013© 2013 Mary G. Carey, PhD, RN, CNS, FAHA