When bradycardia is being treated in ACLS, if an underlying cause cannot be identified and corrected, medications are indicated.
There are three medications used in the bradycardia algorithm: atropine, epinephrine, and dopamine. Each drug and its use within the bradycardia algorithm is explained below.
Atropine
Atropine is the first drug used to treat bradycardia in the bradycardia algorithm. It is classified as an anticholinergic drug and increases firing of the SA Node by blocking the action of the vagus nerve on the heart resulting in an increased heart rate.
Atropine should be used cautiously in the presence of myocardial ischemia and hypoxia since it increases oxygen demand of heart and can worsen ischemia.
The dosing for Atropine is 0.5 mg IV every 3-5 minutes as needed, and the maximum total dosage that can be given is 3 mg.
Atropine should be avoided in hypothermic bradycardia and it will not be effective for Mobitz type II/Second Degree Block Type 2.
You may have read that Atropine is not effective for Mobitz II (2nd-degree block type II) and Complete Heart Block (3rd-degree block)
Click here to find out why
First, let’s look at atropine and how it works. Atropine increases firing of the sinoatrial node (atria) and conduction through the atrioventricular node (AV) of the heart by blocking the action of the vagus nerve.
With 3rd-degree block, there is a complete block and disassociation of the electrical activity that is occurring in the atria and ventricles. Since atropine’s affect is primarily on the SA node in the atria, a 3rd-degree block would prevent its affect on the SA node from influencing the rate of ventricular contraction which is needed to improve perfusion.
With Mobitz-II, aka, Second-degree AV Block Type II, the situation is similar. There is a partial block in the electrical impulses from the atria (SA) to the ventricles, and thus the affects of atropine would not significantly change the status of the ventricles.
This block can also rapidly progress to 3rd-degree block.
To summarize, Atropine may speed the firing rate of the SA node (atria), but the ventricles are not responding to anything the atria (SA node) puts out. Thus, the heart rates will not increase.
There may be some action at the AV-node with atropine, but the effect will be negligible and typically not therapeutic. Atropine in most cases will not hurt the patient with 3rd-degree block unless they are unstable and you delay pacing to give atropine.
It is important to note that Mobitz II and Complete Heart Block may be associated with acute myocardial ischemia. In this case, if atropine is used and it increases the heart rate there is a high potential for worsening of the myocardial ischemia due to the increased oxygen consumption. The increased heart rate will also reduce the diastolic filling time which may worsen coronary perfusion.
Since new onset mobitz II and Complete Heart Block are commonly associated with myocardial infarction, it would be ideal to keep the HR slow (50-60) to increase diastolic filling time. Anytime you increase HR, the diastolic filling time is what takes the biggest hit.
Transcutaneous Pacing should be the first line in symptomatic Mobitz II and Symptomatic Complete Heart Block. It is very safe & less painful than in previous times due to technology improvements. Research has shown that most individuals can tolerate > 15min of transcutaneous pacing without too much difficulty.
Now back to the bradycardia drugs
Epinephrine and Dopamine
Epinephrine and dopamine are second-line drugs for symptomatic bradycardia. They are both used as infusions in the bradycardia algorithm if atropine is ineffective.
ACLS guidelines state that if bradycardia is unresponsive to atropine, an equally effective alternative to transcutaneous pacing is the use of an IV infusion of the beta-adrenergic agonists (dopamine or epinephrine).
Dosing:
Begin the epinephrine infusion at 2 to 10 mcg/min and titrate to patient’s response.
The goal of therapy is to improve the patient’s clinical status rather than target an exact heart rate.
Begin the dopamine infusion at 2 to 20 mcg/kg/min and titrate to the patient’s response.
Precautions
Prior to use of ACLS drugs in the treatment of symptomatic bradycardia, contributing factors of the bradycardia should be explored then ruled out or corrected.
Angela says
Hi I just found this site because I was researching more on bradycardia. I discovered that the symptoms of this condition is exactly what I am experiencing from yesterday low pulse. I have oybeen to the hospital yet but reading your information is of help. I am experiencing shortness of breath at 5 to 10 minutes intervals. What should I do in this situation. …I am a diabetic patient that my medical history . Please I trust that your comment on this will go a long way.
Jeff with admin. says
This website is for education and training. Your symptoms may be very serious and you should see your healthcare provider as soon as possible.
Kind regards,
Jeff
Dr. Rob says
You 100%, without a doubt, should see your doctor immediately. This can be caused by any number of things including, but not limited to:
Heart block
Myocardial ischemia (heart attack)
Sinus node (natural pacemaker) dysfunction.
In a female (especially with diabetes) the symptoms of a heart attack may not be the classic chest pain. You can not assume that this is not something very serious until you have it checked out by a doctor (most likely a cardiologist).
jennifer says
fantastic information on here, thanks for sharing.
Could you explain a little more about why atropine in contraindicated if the patient is hypothermic…. or rather, what could be the outcome if it were administered in this situation?
Many thanks!
Jeff with admin. says
The main reason why atropine is contraindicated for the patient that is hyperthermic is because bradycardia in the presence of hypothermia is typically related to the hypothermia. Reading the cause of the bradycardia by aggressive rewarming will often times reverse the bradycardia.
Also, the hypothermic myocardium may become more irritable with the administration of Atropine or TCP, and drug metabolism may be reduced.
There is also a theoretical concern that medications could accumulate to toxic levels in the peripheral circulation if given repeatedly to the severely hypothermic victim. For these reasons, previous guidelines suggest withholding IV drugs if the victim’s core body temperature is <30°C (86°F).
Hope that helps.
Kind regards,
Jeff
Ronnie says
Could treating a mobitz or complete heart block with atropine actually cause harm to the patient. I am thinking that administering this will increase atrial rate but depending on where the block is, no change in ventricular rate. This increases rate of dissociation and reduced fill times for the heart-maybe causing a PEA?
Thanks
Jeff with admin. says
It is unlikely that the 0.5 mg dose of atropine used for the treatment of symptomatic bradycardia would have such a profound effect to result in PEA as suggested.
Atropine in most cases will not hurt the patient with 3rd-degree block unless they are unstable and you delay pacing to give atropine.
If Atropine has been administered and symptomatic bradycardia does not improve, transcutaneous pacing should be initiated as soon as possible.
Also, determining the level of the heart block prior to treatment can reduce the chance that your interventions will cause harm.
Kind regards,
Jeff
Robyn Parker says
I am wanting to reference this in an assignment; please could you tell me who the author is and the year it was published?
Jeff with admin. says
The author is Jeffery Jack, RN/BSN, and this article was last revised and republished in 2017.
Kind regards,
Jeff
Marco says
I wish there could be a like button for your comments and your excellent information! I come often to your page to get a clear idea of the different cardiovascular situations and their treatments. Thanks for your help!!
I found you on Facebook. Do you have an Instagram page?
Keep the great work! Gracias!
Sincerely,
Marco
Jeff with admin. says
Thanks for the encouraging words. I am so glad that the site has been helpful for you. Unfortunately, at this time, I do not have an Instagram page. Kind regards, Jeff
Alessandro Ciucà says
Hi,
Thank you for the great work you’re doing here
Regarding atropine,in the setting of a intraoperative (so already ongoing anesthesia ,25/30min)rapid bradycardia in a patient with no pregress cardiac symptoms:
-Is 0.5 mg the right dose of atropine?
-Is there any indication do give 1.0 ,also given the fact the patient is more than 70kg (78kg,smoker,diabetic, bmi 29.5)?
Thanks for you help
Alex
Jeff with admin. says
According to AHA guidelines, 0.5 mg of atropine will be the correct dose and subsequent repeat doses can be given if necessary. According to AHA guidelines, there is no indication for giving 1 mg of atropine in a single dose.
Although AHA gives no recommendations for higher doses, I have seen literature that discusses the use of higher doses of atropine for bradycardia that does not respond well to 0.5 mg. In light of this, I would say that the use of higher does is not out of the question.
Kind regards,
Jeff
Andrea Robert says
If you don’t have one of the newer IV pumps that have a dopamine drip program, can anyone share an easy way to give a dopamine infusion?
Jeff with admin. says
Hi Andrea,
Here is brief article that summarizes the process for calculating a dopamine drip: Calculating a Dopamine Drip
Kind regards,
Jeff
susan Conforzi says
I have seen isuprel infusions used for symptomatic bradycardia but it is not mentioned in acls
can you comment on this
thanks
allen rasnick says
the AHA guideline dose for Dopamine for bradycardia is 2 – 20 mcg/kg/min. the ROSC dose for Dopamine is 5-10 mcg/kg/min. we re using the same drug/drip to achieve different results. remember if the heart rate is SLOW start Dopamine LOW to get the desired impact.
GIANMARCO RUFFATTI BATLLE says
In a patient with cetoacidosis and hypovolemic shock that develops bradicardia (44 bpm) due to hyperkalemia, can he receive intensive IV fluid therapy (2 litter normal saline bolus), should he be given atropine (patient has 11/15 glasgow but I believe it is mostly due to hypovolemia and increased osmolarity.)
Jeff with admin. says
Atropine. Followed quickly with 10 units of regular insulin and 50 grams of dextrose.
Also, the intensive IV fluid therapy would be used to correct the hypovolemic shock.
Kind regards,
Jeff
Elaine McKinney says
great information THANKS
Brandon says
DA (Dopamine) is a precursor to Epi. The reason some docs like to use one over the other is as follows: Your myocardium and nervous tissue transport DA into a vesicle that contains a specific enzyme that will convert it to Epi and then that vesicle must be trafficked to the proper receptor (typically on the outside of the cell) that will cause increased permeability to calcium and eventual muscle contraction. If you give Epi, you bypass this conversion system and get the effect you want sooner. Both are relatively quick processes, it just comes down to personal preference.
Kev says
In relation to the “Bainbridge Reflex”… would aggressive IV fluid treatment not be an effective way of raising heart rate in patients with symptomatic bradycardia? This is not what is indicated pre-hospital – so why not?
Jeff with admin. says
I’m not sure what the mean by brain bridge reflex but fluids will not stimulate the sympathetic nervous system. Atropine will increase heart rate. Transcutaneous pacing will increase heart rate.
Kind regards,
Jeff
Ethan says
Speaking from an SNS perspective, wouldnt aggressive IV fluids end up decreasing the heart rate further due to a rise in blood pressure? HR increases with a drop in blood pressure such as in hypovolemic shock so IV fluids would not elicit the desired response here.
It’s all situation as to the contributing factors leading to the bradycardia.
sarfaraz says
Dopamine dose in bradycardia?
http://emedicine.medscape.com/article/2172085-overview
Jeff with admin. says
This document is from 2014. The AHA guidelines were released in late 2015. Prior to 2015, the AHA Guidelines for dopamine was 2-10 mcg/kg/min. This was changed to 2-20 mcg/kg/min in 2015. Kind regards, Jeff
Hilgendh says
What’s the major differences between Dopamine and Epinephrine besides the dose ranges? In my readings, i see that dopamine is a precursor to epi, and that both have a Beta- effect at low doses and an increasing Alpha effect at higher doses. Why is epinephrine prefered for everything? What would be reasons to choose one over another?
Thanks!!!
Jeff with admin. says
For the treatment of bradycardia, dopamine or epinephrine infusions are both classified equal in their effect (Class IIb LOE B) and either choice would be equally acceptable for the treatment of symptomatic bradycardia.
The major difference would be that if you have a patient who is hypotensive along with the bradycardia, epinephrine would probably be a better choice to start with. This is due to the fact that epinephrine can simultaneously increase the heart rate and blood pressure. Whereas with dopamine, you have to titrate different doses to achieve either an increase in heart rate or increased blood pressure.
I would not say that epinephrine is always preferred for everything. I have often seen a physicians first choice for hypotension or bradycardia be dopamine.
Kind regards, Jeff
SheilaK says
The dopamine infusion rate – on the algorithm chart it states 2-10 mcg/kg/mn but on the information above in bold it states 2-20mcg/kg/mn. Which is the correct dose?
Jeff with admin. says
Can you please let me know which “algorthm chart” you are asking about? The correct dosing is 2-20 mcg/kg/min.
Is the 2-10 mcg/kg/min dosing you referenced from this website or another chart you are looking at?
Kind regards,
Jeff
Ellen Mosca says
On the AHA ACLS Bradycardia Algorithm listed on this site
Jeff with admin. says
If you can provide the link to the algorithm you are looking at that would be great. I cannot locate any bradycardia algorithm on the site that lists dopamine infusion for bradycardia at 2-10 mcg/kg/min. The correct dosing is 2-20 mcg/kg/min. Kind regards, Jeff
Ren says
EPI is for if BP >100 systolic
Dopamine is used if BP <100 systolic
That is, if TCP is unavailable or treatment is contraindicated.
britt says
this is incorrect. Epi raises both HR and BP, dopa is better for raising HR but can also raise BP depending on the dosage.