Case:
70 yo F arrives as level 2 trauma for fall with head trauma on blood thinners. Patient had a syncopal event which led to the fall.
Initial vitals: HR 38, RR 18, BP 110/80, 97% on RA
Exam: Bruising to forehead, slow to answer questions, AOx3, non-focal neurologic exam
Flow of the Case:
Patient arrives bradycardic, normotensive and provides a history of syncope
> EKG shows:
ECG from https://litfl.com/av-block-3rd-degree-complete-heart-block/
> ECG interpretation: 3rd degree heart block
> The patient becomes hypotensive and less responsive
> Atropine is attempted and does not improve the bradycardia
> Transcutaneous pacing is initiated but only captures at 80mA and improves BP
> Cardiology is consulted and patient goes to cath lab for pacemaker placement
Learning Objectives:
Consider Differential Diagnosis for Bradycardia:
Medications/Tox:
o Beta-blocker, calcium channel blockers, clonidine, digoxin, cholinergic medications
Metabolic:
o Hyperkalemia, hypermagnesemia, hypothyroid, hypothermia
o Severe hypoxia, hypercarbia, hyperacidemia (bradycardia often indicator of impending death)
o Myocardial Infarction
o Anterior Wall MI (LAD) – can cause death of the conduction system (often does not respond to atropine or pacing)
o Inferior wall MI (RCA) – less severe blocks due to vagal irritation, typically responsive to atropine
The Pharmacology for Bradycardia:
o Atropine 0.5mg IV push every 3-5 min, may be repeated up to total dose of 3mg
o Epinephrine push dose or epinephrine gtt 2-10 mcg/min
How do I make push dose epi?
10ml syringe of NS, remove 1ml > draw up 1ml of cardiac epinephrine (100mcg/ml) into the syringe > now you have 10mls of 10mcg/ml
Why should I pace?
o Attempt transcutaneous pacing in unstable bradycardia or if patient is not responding to medical therapy for bradycardia
How to pace:
o Turn control dial to green pacer control
o Set rate (usually ~70 bpm)
o Set mA to capture (usually captures 40-80mA) – if patient CRASHING > start high then go low.. otherwise okay to slowly increase by 10mA until you get ventricular capture
How to confirm capture:
o Spike followed by a wide QRS + palpable pulse that correlates with set pace
ECG from https://www.aclsmedicaltraining.com/blog/transcutaneous-pacing-tcp-without-capture/
o Do not be fooled by pseudo-pacing – just because you see pacer spikes on monitor, confirm that the heart is actually beating at the set rate!
A final checklist:
Check: Pulse oximetry waveform shows a pulse matching the pacemaker
Check: Bedside echocardiogram confirms myocardial contraction with pacing
Check: Pulse, preferably far away from the chest
Written by Dr. Emily Dedonato, MD
Cook County Health, Simulation Fellow
For more Sim information: https://www.chicagosimfellowship.com/features.