Timeline:

• Divide learners into 4 groups at different tables (this approach is suggested for groups of 8 or more

learners and should be modified to 1 or 2 groups so sites with lower numbers of learners)

• 5 min large group review of the Unit 4 Summary “Approach to Bradyarrythmias”

• Give each group 2 copies of the Unit 4 EKG Challenges Packet (merged challenge EKG content for EKGs 13

-16), this allows learner groups to all review content and record their group's answers to the

interpretation and questions for each EKG

• Allow 20 minutes for groups to complete the 4 challenges (give updates at 5min increments)

• 20 minutes large group discussion of answers to challenges. May consider asking each group to present

their responses to a different EKG

Meeting Resources:

• Notify learners in advance of the session that they need to review the unit summary and challenge EKGs

• Before the session, have a few copies of the unit summary (pages 2-6 of this document) printed to give to

learners who forgot their copies/devices and copies of the Unit 4 EKG Challenges Packet to give to groups

• Before the session, make sure to print this document for your own reference during the group discussion

• After the meeting, send out the answer document to learners for independent review

Foundations EKG I

Unit 4 Instructor—Approach to Bradyarrhythmias

Foundations EKG I

Unit 4 Instructor—Approach to Bradyarrhythmias

Unit 4, Case 13—59y/o F with PMH of HTN presents from her PCP for an abnormal ECG. She reports feeling asymptomatic. She was recently started on carvedilol by her primary care physician for her blood pressure. What is your diagnosis based on the history and ECG findings? Are there any therapies that you would initiate in the ED? How would you disposition this patient?

HR: 66 BP: 140/90

RR: 12 O2 Sat: 100%

Unit 4, Case 16—82 y/o F with a PMH of CAD and ischemic cardiomyopathy with an EF of 45% presents for syncope. She arrives pale and diaphoretic and reports feeling lightheaded. What initial actions would you take in the ED? What reversible precipitants of the patient’s current condition would you want to evaluate for? How would you disposition this patient?

HR: 28 BP: 72/40

RR: 20 O2 Sat: 95%

Unit 4, Case 15—70yM with history of CAD, HTN, HL presents after a syncopal episode while walking. An EKG from 1 year ago shows NSR with a right bundle branch block. What are your next steps for this patient?

HR: 42 BP: 100/60

RR: 16 O2 Sat: 100%

Unit 4, Case 14—70yM with history of CAD, HTN, HL presents after a syncopal episode while walking. An EKG from 1 year ago shows NSR with a right bundle branch block. What is the definitive treatment for this patient?

HR: 42 BP: 100/60

RR: 16 O2 Sat: 100%

Foundations EKG I - Unit 4 Summary

Approach to Bradyarrhythmias

Bradyarrhythmias can be secondary to a variety of causes. Determining the specific type of bradyarrhythmia

helps pinpoint where in the heart trouble might lie. Often evaluation requires careful inspection of the rhythm

strip and sometimes of a prolonged 12 lead EKG.

Sinus bradycardia may be due to normal functioning of the heart, or can be caused by electrolyte abnormalities or

pharmacological influences. A rate under 60 bpm in normal adults is considered bradycardic. Note in sinus bradycardia

the rhythm has normal conducting p waves followed by a QRS with normal intervals. In symptomatic patients atropine

is an appropriate first treatment while trying to identify other reversible causes.

Understanding the intrinsic rates of various pacemaker foci within the heart will help you distinguish the

main driver of an impulse. In a normal, healthy heart the SA node is the only pacemaker you will see on the

EKG.

• SA node: 60-100 bpm

• Atria: 60-80 bpm

• Junctional: 40-60 bpm

• Ventricular: 20-40 bpm

In the above example we see a rate of approximately 40 bpm. There are no p waves. The QRS is narrow

(distinguishing it from ventricular conduction in many cases.) It is an example of a junctional rhythm causing

bradycardia.

Courtesy of Susan Torrey of TorreyEKG.com

A rhythm with a progressively prolonging PR interval that eventually leads to a dropped beat, followed by a short

PR interval that again progressively prolongs is consistent with a 2nd Degree AV block, Mobitz I (also known as

Wenckebach Phenomenon).

In an asymptomatic patient, this rhythm is benign with low risk of hemodynamic instability and relatively rare pro-

gression to third degree heart block. Atropine usually works for symptomatic patients.

Possible causes include:

• Beta-blocking and calcium channel blocking drugs

• Myocarditis

• Inferior MI

• Increased vagal tone

Courtesy of Edward Burns of Life in the Fast Lane

Creative Commons License

Courtesy of Edward Burns of Life in the Fast Lane

Creative Commons License

Intermittently dropped beats with normal PR intervals are consistent with 2nd degree AV block, Mobitz II. In this pattern

the beat is dropped without any predicable pattern. This rhythm is much more likely to cause hemodynamic instability

than Mobitz I and may develop into third degree heart block. In addition to investigating possible causes these patients

should be immediately admitted for permanent pacemaker placement.

In third degree heart block (also known as complete heart block), the supraventricular impulses are not conducted to

the ventricles. QRS complexes march through the rhythm strip completely independently of the p waves. The

perfusing rhythm is the ventricular rhythm causing severe bradycardia. Even in patients with a normal blood pressure

who are asymptomatic this is a serious emergency—these patients are at risk for ventricular standstill. In symptomatic

or hypotensive patients pacing (external or internal) is indicated. Immediate permanent pacemaker placement is

imperative.

When there is no conduction from supraventricular impulses the rhythm seen is a ventricular escape rhythm. In

this case the only impulses seen on an EKG are the ventricular QRS complexes at a rate of 20-40 bpm. The QRS is

widened in this case because the impulse is from an ectopic focus lying outside of the His-Purkinje system.

Definitive management requires immediate permanent pacemaker placement.

Created by Ashley Deutsch, MD Edited by Nick Hartman, MD; Shanna Jones, MD; & Kristen Grabow Moore, MD, MEd

59y/o F with PMH of HTN presents from her PCP for an abnormal ECG. She

reports feeling asymptomatic. She was recently started on carvedilol by

her primary care physician for her blood pressure.

HR: 66 BP: 140/90

RR: 12 O2 Sat: 100%

What is your interpretation of the EKG?

History/Clinical Picture

Rate

Rhythm

Axis

P Waves

Q/R/S Waves

T Waves

U Waves

PR Interval

QRS Width

ST Segment

QT Interval

What is your diagnosis based on the history and ECG

findings?

Are there any therapies that you would initiate in the ED?

How would you disposition this patient?

Foundations EKG I - Unit 4, Case 13

Triage EKG—Unit 4, Case 13

EKG courtesy of Shanna Jones, MD

What is your interpretation of the EKG? History/Clinical Picture— A relatively healthy middle aged woman presents for a reportedly abnormal EKG

Rate— 66

Rhythm— Second degree AV nodal block, type 1 (Wenkebach or Mobitz I). This rhythm is defined by a PR interval that ex-tends until a beat is dropped. Therefore the PR must be shortest immediately after a dropped beat and longest just before one (can’t measure a PR on a dropped beat because there is no R wave). Also, the P-P interval is usually stable.

Axis— normal P Waves— normal Q, R, S Waves— no pathologic q-waves, poor R wave progression with low amplitude R waves throughout the precordium

T Waves— normal, relatively flat but proportionate to their R waves

U Waves— none

PR Interval— increasingly prolonged, leading to a dropped beat

QRS Width— normal ST Segment— normal, no ST elevation or depression

QT Interval— normal Diagnosis: Second Degree Atrioventricular Block, Type 1 Discussion: Because this patient is asymptomatic, no treatment is indicated at this time. Mobitz I is a benign rhythm and risk of progression to complete heart block is low. AV nodal blocking agents may precipitate this rhythm, and so the patient’s primary care physician may want to consider discontinuing the recently added beta-blocker in favor of an anti-hypertensive without AV nodal blocking properties. If a patient is symptomatic with a second degree AV block type I, it may be reasonable to try atropine (to reduce parasympathetic tone) or isoproterenol (to increase chronotropy). Symptomatic patients should be admitted for evaluation by cardiology. Asymptomatic patients can be discharged home with routine follow up.

Resource Links: Life in the Fast Lane — great overview Dr. Steve Smith’s Blog – good case

Created by William Burns, MD & Duncan Wilson, MD Edited by Nick Hartman, MD & Kristen Grabow Moore, MD, MEd

Unit 4, Case 13—2nd Degree, Type 1 AV Block

Drop Drop Drop

PR PR PR

Drop

PR PR PR PR PR PR PR PR PR

70yM with history of CAD, HTN, HL presents after a syncopal epi-

sode while walking. An EKG from 1 year ago shows NSR with a

right bundle branch block.

What is your interpretation of the EKG?

History/Clinical Picture

Rate

Rhythm

Axis

P Waves

Q/R/S Waves

T Waves

U Waves

PR Interval

QRS Width

ST Segment

QT Interval

What is the definitive treatment for this patient?

Foundations EKG - Unit 4, Case 14

HR: 42 BP: 100/60

RR: 16 O2 Sat: 100%

Triage EKG—Unit 4, Case 14

EKG courtesy of Shanna Jones, MD

What is your interpretation of the EKG?

History/Clinical Picture—elderly, syncopal episode

Rate—42

Rhythm—Sinus with intermittent dropped beats

Axis—Right Axis Deviation (I neg, aVF positive)

P Waves—normal

Q, R, S Waves—RSR’ in V1

T Waves—Normal

U Waves—None

PR Interval—Fixed with normal conduction through the AV node but intermittent dropped beats

QRS Width—Wide at ~140ms in V1

ST Segment—No ST elevation or depression

QT Interval—Normal

Diagnosis—Second Degree AV Block Type II because there is no indication of PR prolongation that would be suggestive of Second Degree AV Block Type I (Wenckebach). RBBB is also present given RSR’ in V1 and prolonged QRS.

What is the definitive treatment for this patient?

Permanent pacemaker placement. Any 2nd degree block that is not clearly Type I (Wenckebach) should be assumed to

be Type II and the patient should be admitted for a cardiology/electrophysiology consult to determine if the is an

indication for a pacemaker.

EKG Resource Links: Life in the Fast Lane Dr. Ken Grauer’s Blog

Created by William Burns, MD Edited by Nick Hartman, MD & Kristen Grabow Moore, MD, MEd

Unit 4, Case 14—2nd Degree, Type 2 AV Block

Drop Drop Drop

PR PR PR PR

Drop Drop

PR PR

Drop

PR PR PR PR PR

70yM with history of CAD, HTN, HL presents after a syncopal epi-

sode while walking. An EKG from 1 year ago shows NSR with a

right bundle branch block.

What is your interpretation of the EKG?

History/Clinical Picture

Rate

Rhythm

Axis

P Waves

Q/R/S Waves

T Waves

U Waves

PR Interval

QRS Width

ST Segment

QT Interval

What are your next steps for this patient?

Foundations EKG I - Unit 4, Case 15

HR: 42 BP: 100/60

RR: 16 O2 Sat: 100%

Triage EKG—Unit 4, Case 15

What is your interpretation of the first EKG?

History/Clinical Picture—elderly man with lightheadedness

Rate—42

Rhythm—Unclear. As demonstrated in the ladder diagram below QRS complexes 6/7 seem to have a consistent PR

interval but none of the other QRS other complexes are preceded by P waves.

Axis—Mild Left Axis Deviation (I pos, aVF neg, II neg)

P Waves—normal morphology, more P waves than QRS complexes (as seen below in ladder diagram)

Q, R, S Waves—non-pathologic Q waves in I & aVL, R & S waves normal

T Waves—T wave inversion in V1/2 and III.

U Waves—None

PR Interval—no consistent PR interval

QRS Width—normal

ST Segment—no ST elevation or depression

QT Interval—normal

Diagnosis: 3rd Degree AV Block (Complete Heart Block)

P Waves

AV Node

QRS Complexes

Unit 4, Case 15—3rd Degree AV Block

What treatment options do you have for this patient? Presuming the patient is maintaining his triage blood pressure of 100/60 you are unlikely to need to pace them immediately so while preparing to pace if needed try to figure out why they are in a 3rd degree block IV, O2, Monitor Place defibrillation/transcutaneous pacing pads Transvenous Pacer kit to the bedside Send complete set of labs including CBC, BMP, Magnesium, Phosphorus, Ionized Calcium, Troponin, BNP with a VBG or iStat to facilitate rapid assessment of the potassium level if possible Focused cardiac and medication history as well as screening for Lyme or hypothyroidism Complete head to toe exam with a special focus on tissue perfusion and mental status Consult cardiology If the patient becomes unstable, attempt transcutaneous pacing and then transvenous if necessary. If pacing is ineffective at increasing the heart rate and/or the blood pressure ACLS also recommends using dopamine or epinephrine infusions

EKG Resource Links: Life in the Fast Lane Dr. Steve Smith’s Blog Dr. Ken Grauer’s Blog

Created by William Burns, MD Edited by Nick Hartman, MD; Shanna Jones, MD; & Kristen Grabow Moore, MD, MEd

Image courtesy of Kristen

Grabow Moore, MD, MEd

Unit 4, Case 15—3rd Degree AV Block

Introducer Sheath (Cordis)

82 y/o F with a PMH of CAD and ischemic cardiomyopathy with

an EF of 45% presents for syncope. She arrives pale and

diaphoretic and reports feeling lightheaded.

HR: 28 BP: 72/41

RR: 20 O2 Sat: 95%

What is your interpretation of the EKG?

History/Clinical Picture

Rate

Rhythm

Axis

P Waves

Q/R/S Waves

T Waves

U Waves

PR Interval

QRS Width

ST Segment

QT Interval

What initial actions would you take in the ED?

What reversible precipitants of the patient’s current con-

dition would you want to evaluate for?

How would you disposition this patient?

Foundations EKG I - Unit 4, Case 16

Triage EKG—Unit 4, Case 16

EKG courtesy of Shanna Jones, MD

What is your interpretation of the EKG? History/Clinical Picture—elderly woman with ischemic cardiomyopathy & hemodynamic instability

Rate—30

Rhythm—ventricular escape

Axis—difficult to assess given low amplitude and rare QRS complexes however there is likely left axis deviation LAD) given that I is positive and II & aVF are predominately negative. Additionally, there is left bundle branch block morphology which also supports LAD.

P Waves—none present

Q, R, S Waves—LBBB morphology is present with deep QS complexes in V1-V3

T Waves—diffuse inversion possibly resulting from LBBB, tall T waves in V1-V3 consistent with LBBB

U Waves—none present

PR Interval—not present

QRS Width—abnormally wide at 140-160ms

ST Segment—no significant ST elevation or depression

QT Interval—prolonged. QT is 720ms with QTc of approximately 540ms

Diagnosis: sinus arrest with ventricular escape rhythm

What initial actions would you take in the ED? The ventricles are pacing the heart at their inherent rate of 20-40 beats per minute as higher pacemakers (the sinus node and AV node) have failed. Emergent treatment of this hemodynamically unstable bradycardia include medications (atropine, isoproterenol, dopamine, epinephrine). If medications fail then transcutaneous or transvenous pacing is the next step. What reversible precipitants of the patient’s current condition would you want to evaluate for? The emergency physician should seek to identify any reversible precipitants of the bradycardia. Common reversible causes include ischemia, hyperkalemia, and medication overdose (beta-blockers, calcium channel blockers, and digoxin). Reversible causes should be treated. How would you disposition this patient? If the bradycardia persists, the patient should be admitted to an ICU. If the patient is hemodynamically stable they may be appropriate for a monitored floor with electrophysiology consult for permanent pacemaker consideration.

Resource Links: Life in the Fast Lane — great overview Dr. Steve Smith’s Blog – good case

Created by Duncan Wilson, MD Edited by Nick Hartman, MD; Shanna Jones, MD; & Kristen Grabow Moore, MD, MEd

Unit 4, Case 16—Ventricular Escape