Heart Rate: Goals, Differential Diagnosis, and the Drugs That Change It

CA-1 · draft

CA-1 Bootcamp day 6. Authored from cited abstracts; every claim carries a PMID.

Not reviewed. This deck cannot be opened, downloaded or sent until you approve it. Read every point and its source first — they were drafted from search results, not from clinical judgement.

Before induction

The top of the adult range is the end that tracks with harm: in the VISION cohort a maximum intraoperative heart rate above 100 beats per minute was associated with myocardial injury, myocardial infarction and 30-day mortality, and a separate cohort analysis found the definition of intraoperative tachycardia with the strongest predictive power for death and infarction was a heart rate of at least 100 sustained for at least 30 minutes.
The bottom of the range is far less frightening than residents expect — in the same VISION analysis a minimum intraoperative heart rate below 55 beats per minute was associated with less myocardial injury and lower mortality, and a retrospective analysis of time spent above 90 beats per minute found no association with myocardial injury at all, so a slow rate with a good pressure is a number to explain rather than a number to chase.
Most intraoperative bradycardia in a healthy adult is drug or reflex rather than disease: in a multivariable analysis of adult surgical records the strongest predictor was the absence of anticholinergic premedication, with propofol induction and neuraxial blockade adding risk, and neostigmine-glycopyrrolate reversal is itself a dose-dependent cause of both bradycardia and tachycardia in the same patient.
Glycopyrrolate and atropine both raise heart rate, but glycopyrrolate protects better against neostigmine-induced bradycardia while producing less initial tachycardia, fewer arrhythmias and less junctional rhythm, whereas intravenous atropine produces the more marked and more immediate tachycardia — which is why glycopyrrolate is the routine partner for neostigmine and atropine is what you reach for when you need rate right now.
Esmolol is a cardioselective beta-1 blocker with rapid onset and a short duration of action, which is exactly why it suits a heart rate you want under control within minutes and are willing to hand back afterwards; its main tolerability cost is hypotension, and that hypotension is itself rapidly reversible.
Labetalol antagonises alpha-1 as well as beta-1 and beta-2 receptors, so it lowers blood pressure and peripheral resistance with a less pronounced fall in heart rate than a pure beta-blocker, while metoprolol is the longer-acting beta-1 choice — and POISE is the reason nobody starts a beta-blocker on the morning of surgery, because extended-release metoprolol cut myocardial infarction from 5.7% to 4.2% but raised stroke from 0.5% to 1.0% and death from 2.3% to 3.1%.

Questions in the room

The heart rate moved and the blood pressure did not — what does that combination tell you that either number alone does not?
Before you treat this rate, what have you actually excluded: light anaesthesia, hypovolaemia, pain, hypercarbia, fever, the surgeon pulling on something?
How long do you want this effect to last? Now pick the drug whose duration matches that answer.
If you slow this heart and the blood pressure follows it down, what is your next move — and do you have it drawn up?

Oral boards stem

You are anaesthetising a 68-year-old with hypertension and a remote drug-eluting stent for an open right hemicolectomy. Forty minutes in, at roughly 1 MAC of sevoflurane, with the blood pressure stable at 118/70 and the surgeon working deep in the pelvis, the heart rate climbs from 72 to 118 and stays there. The examiner wants you to talk through what you would consider before you touch a syringe, what you would do first, and — if you decided the rate itself needed treating — which drug you would give, at what dose, and how long you expect that decision to bind you.

Sources

Abbott et al., Anesth Analg 2018 PMID 29077608
Shcherbakov et al., Eur J Anaesthesiol 2022 PMID 34690273
Ruetzler et al., Eur J Anaesthesiol 2019 PMID 30507620
Yorozu et al., J Anesth 2007 PMID 17458640
Shay et al., Anesth Analg 2020 PMID 30896593
Ostheimer, Anesth Analg 1977 PMID 322545
Oduro, Can Anaesth Soc J 1975 PMID 1139387
Takkunen et al., Acta Anaesthesiol Scand 1984 PMID 6485732
Wiest et al., Clin Pharmacokinet 2012 PMID 22515557
Garnock-Jones, Drugs 2012 PMID 22191799
Carter, Drug Intell Clin Pharm 1983 PMID 6354658
Devereaux et al., Lancet 2008 PMID 18479744
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