Peter Antevy explains that unstable bradycardia is defined by hypotension, not symptoms. Treating rate with atropine during an MI can worsen ischemia. External pacing is first-line for hypotensive bradycardic patients, with 6 mg IV etomidate for sedation.
Questions this video answers
Presence of hypotension (low blood pressure).
Etomidate 6 mg IV.
Chapters
We're going to talk about bradycardia and what unstable bradycardia really means. And we actually look up unstable at BradyCardia and ACLS. It talks about things like chest pain, dizziness, short of breath, etc. Those things, in my mind, don't make you unstable. What makes you unstable with bradycardia is if you are hypotensive. And the reason why we have this distinction is because sometimes bradycardia is the cause of symptoms and sometimes bradycardia is a symptom of whatever the cause is. And let me give you an example of what I mean. If you are having an inferior wall or right ventricular infarct, the blood supply to the sinus node may be interrupted, leading you to have bradycardia. In this case, the patient's chest pain is from the mi, not from the bradycardia. The bradycardia is because you're having an mi. If you were to give that person atropine, you've now increased the myocardial oxygen demand of the heart. You've made the MI worse.
So the answer for bradycardia is not to give them all atropine just because of the pulse rate. So remember the old adage, treat the patient, not the monitor. If your patient is hypotensive and bradycardic, you yes. Then the problem is, at least in part, bradycardia. Those folks don't have enough cardiac output to maintain enough blood pressure. So it's not an absolute number that we're trying to fix. It's not that we want to get everybody above 60. It has to be. You have to look at the heart rate along with the blood pressure, along with the symptoms. So an asymptomatic patient whose heart rate is slow needs nothing. A patient who has chest pain, whose heart rate is slow, yet their blood pressure is fine, atropine can make them worse if necessary. You've got a patient who is bradycardic and they may be having an mi and you're deciding whether to give them atropine or pace them because they're hypotensive. Keep in mind that pacing is probably the right thing to do in that scenario, because pacing can be fine tuned to get them just up to maybe 60 or 65, just enough to give them some increased cardiac output so their blood pressure comes up. If you give them atropine, it's really unpredictable what their heart rate's going to go to. And if you end up overshooting and making that person at 100, well, you've sort of done them a disservice because while in both scenarios you are increasing the oxygen demand on the heart by making it go faster, clearly there's a difference between raising them by a external pacemaker to 60 versus giving them atropine and giving them up to 100. So our first line of therapy in these folks where they're hypotensive and yes, they're having an MI and yes, they are bradycardic, we want to use our external pacemaker as first line for these folks to try to gently raise their blood pressure and heart rate up. So on those folks, the pacing is painful and we once again have etomidate 6mg IV as a low dose to give them enough sedation so they can tolerate the third therapy.
