9/18/2013

1

Challenging Cardiac

Arrhythmias:

A Case-Based Approach

Critical Care Symposium 2013 Mary G Carey, PhD, RN, CNS, FAHA

Associate Director, Clinical Nursing Research Center, Strong

Memorial Hospital

Associate Professor, School of Nursing

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

Recommendations vary regarding initial

competency

It is unknown what is necessary 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

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2

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 wide

Fixed or variable

Interpretation?

The ECG Paper Horizontally (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

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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?

3

sec

3

sec

Option 2

Find an 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

9/18/2013

4

Marriott's Practical Electrocardiography

GS Wagner & HJL Marriott

0.12-0.20 (3-5 boxes)

<0.12seconds (3 boxes)

Rhythm

• Rate?

• Regularity?

• P waves?

• PR interval?

• QRS duration?

Interpretation?

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Rhythm

• Rate?

• Regularity?

• P waves?

• PR interval?

• QRS duration?

Interpretation?

Rhythm

• Rate?

• Regularity?

• P waves?

• PR interval?

• QRS duration?

Interpretation?

9/18/2013

6

Rhythm

• Rate?

• Regularity?

• P waves?

• PR interval?

• QRS duration?

Interpretation?

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

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• Rate?

• Regularity?

• P waves?

• PR interval?

• QRS duration?

Interpretation?

24 year old trauma patient (lead I)

• Rate?

• Regularity?

• P waves?

• PR interval?

• QRS duration?

Tri- athlete

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12 Lead ECG Limb leads

Precordial leads

Rhythm strip

72 yo male, routine resting 12-lead ECG

9/18/2013

9

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 (Pietrasik

et al. 2007)

• Regional fQRS patterns predict regional infarction

in the absence of Q waves (Mahenthiran, et al. 2007)

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I

aVR

II

III

aVF

ECG Methodology

V1

V3

V5

V4

V6

V2

Characteristics of the 12-lead

Holter ECG in Professional

Firefighters

National Institutes of Health Grants R21 NR011077

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Recognizing ST Deviation

Normal Ischemia, ST depression Injury, ST elevation

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Single Lead Monitoring Lead II

Interpretation?

• Rate?

• Regularity?

• P waves?

• PR interval?

• QRS duration?

Injury is regional, not global

Interpretation?

9/18/2013

14

Challenging Cardiac

Arrhythmias:

A Case-Based Approach

Critical Care Symposium 2013 Mary G Carey, PhD, RN, CNS, FAHA

Associate Director, Clinical Nursing Research Center, Strong

Memorial Hospital

Associate Professor, School of Nursing

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