1 Bradycardia Algorithm Review Romulo B. Babasa III, MD

2 Case Scenario An 87-year-old woman reports feeling weak and short of breath for 2 hours while walking short distances. She feels exhausted moving from the car to the ED stretcher. On physical exam she is pale and sweaty; HR = 35 bpm; BP = 90/60 mm Hg; RR = 18 rpm. Rhythm: see next slide.

3 87-Year-Old Woman: Symptomatic Bradycardia t Identify A, B, and C t Which one is most likely to be her rhythm? A B C

4 Rhythms to Learn t Sinus bradycardia t Heart blocks 1 st degree 2 nd degree type I 2 nd degree type II 3 rd degree

5 Cardiac Conduction System 1 Left bundle branch Posterior division Anterior division Purkinje fibers Right bundle branch Bundle of His AV node Internodal pathways Sinus node

6 Cardiac Conduction System 2

7 Rates of Intrinsic Cardiac Pacemakers t Primary pacemaker Sinus node ( bpm) t Escape pacemakers AV junction (40-60 bpm) Ventricular (<40 bpm)

8

9 Determining the Rate

10 Determining the Rate

11 Analyzing Rhythm Strips t Key questions Are QRS complexes present? Are P waves present? How is the P wave related to the QRS complex?

12 Relationship of P Waves and QRS Complexes t Every P wave is followed by a QRS complex with a normal P–R interval t Every P wave is followed by a QRS complex but the P–R interval is prolonged t Some P waves are not followed by a QRS complex; more P waves than QRS complexes

13 What Is This Rhythm?

Sinus Bradycardia 14

15 What Is This Rhythm?

16 First Degree AV Block

17 Diagnosis?

18 Second Degree AV Block Type I

19 Diagnosis?

20 Second Degree AV Block Type II

21 What Is This Rhythm?

22 Third Degree AV Block Type III

23 Differentiation of Second- and Third-Degree AV Blocks More P’s than QRSs PR fixed? no QRSs that look alike regular? no yes 2 nd -degree AV block Fixed Mobitz II 3 rd -degree AV block 2 nd -degree AV block Variable Mobitz I Wenckebach

24 Bradycardia Algorithm (1 of 2) Bradycardia Heart Rate less than 60 bpm and inadequate for clinical condition Maintain patent airway; assist breathing as needed Give oxygen Monitor ECG (identify rhythm), blood pressure, oximetry Establish IV access Serious signs or symptoms of poor perfusion caused by the bradycardia? (eg. acute altered mental status, ongoing chest pain, hypotension or other signs of shock)

25 Bradycardia Algorithm (2 of 2) Observe/Monitor Prepare for transvenous pacing Treat contributing causes Consider expert consultation Poor Perfusion Adequate Perfusion Prepare for transcutaneous pacing; use without delay for high degree block (type II second -degree block or third- degree AV block) Consider Atropine 0.5 mg/IV while awaiting pacer. May repeat to a total dose of 3 mg. If ineffective, begin pacing. Consider Epinephrine ( 2 to 10 µg/min) or dopamine ( 2 to 10 µg/kg/min infusion while awaiting pacer or if pacing ineffective. Reminders If pulseless arrest develops go to Pulseless Arrest Algorithm Search for and treat possible contributing factors: H ypovolemia H ypoxia H ydrogen ion (acidosis) H ypo/Hyper-kalemia H ypoglycemia H ypothermia T oxins T amponade, cardiac T ension pneumothorax T hrombosis (coronary or pulmonary) T rauma (hypovolemia, inc ICP)

26 What Is This Rhythm?

27 Treatment?

28 Treatment?

Transcutaneous Pacing 29

30 Indications for Transcutaneous Pacing t Hemodynamically unstable bradycardias t In the setting of AMI: sinus node dysfunction, type II 2 nd -degree block, 3 rd -degree heart block t Bradycardia with symptomatic ventricular escape beats

Transcutaneous Pacing 31

Transcutaneous Pacing t The pacing rate is set at 80 beats per minute. t In conscious bradycardic patients, pacing is begun in the demand mode at rates slightly faster than the native rhythm and at minimal current output t The current is gradually increased by 5 to 10 mA at a time until cardiac capture is documented, which defines the pacing threshold. The final current output should be set at the pacing threshold or 5 to 10 mA above it. 32

Transcutaneous Pacing t In the setting of a bradysystolic arrest or with unconscious patients, it is recommended to turn the stimulating current to maximal output (200 mA) to ensure ventricular capture t Once capture is achieved, the current may be gradually decreased until loss of capture, which defines the pacing current threshold 33

34 Transcutaneous Pacing

35 Transcutaneous Pacing: “Capture” vs “No Capture” Pacing below threshold: no capture Pacing above threshold: with capture Pacing Spike Capture: Spike + broad QRS QRS: opposite polarity 25 Feb 88 Lead I Size 1.0 HR=41 25 Feb 88 Lead I Size 1.0 HR=43 35 mA 25 Feb 88 Lead I Size 1.0 HR=71 60 mA Bradycardia: No Pacing Pacing Below Threshold (35 mA): No Capture Pacing Above Threshold (60 mA): With Capture (Pacing-PulseMarker ) Bradycardia: no pacing