The major ECG rhythms classified as bradycardia include:
- -Sinus Bradycardia
- -First-degree AV block
- -Second-degree AV block
- -Type I —Wenckebach/Mobitz I
- -Type II —Mobitz II
- -Third-degree AV block complete block
Bradycardia vs. Symptomatic Bradycardia
Bradycardia is defined as any rhythm disorder with a heart rate less than 60 beats per minute. (Usually less than 60)
Symptomatic bradycardia, however, is defined as a heart rate less than 60/min that elicits signs and symptoms, but the heart rate is typically less than 50/min.
Symptomatic bradycardia exists when the following 3 criteria are present: 1.) The heart rate is slow; 2.) The patient has symptoms, and 3.) The symptoms are due to the slow heart rate.
Relative bradycardia occurs when a patient may have a heart rate within normal sinus range, but the heart rate is insufficient for the patient’s condition. An example would be a patient with a heart rate of 80 bpm when they are experiencing septic shock.
Bradycardia Pharmacology
There are 3 medications that are used in the Bradycardia ACLS Algorithm. They are atropine, dopamine (infusion), and epinephrine (infusion). More detailed ACLS pharmacology information is reviewed following this page.
- The single dose administration of atropine was increased from 0.5 mg to 1 mg. Now give 1 mg for the first dose and then repeat every 3-5 minutes at the 1 mg dose.
- Also, the dopamine infusion rate for chemical pacing was changed to 5-20 mcg/kg/min.
The previous rate from the 2015 guidelines was 2-20 mcg/kg/min. - The demand rate may be set at a range from 60-80/min. 2015 guidelines had the start demand rate to start at only 60/min.
2015 AHA Update: For symptomatic bradycardia or unstable bradycardia IV infusion a chronotropic agent (dopamine & epinephrine) is now recommended as an equally effective alternative to external pacing when atropine is ineffective.
Atropine: The first drug of choice for symptomatic bradycardia. The dose in the bradycardia ACLS algorithm is 1 mg IV push and may repeat every 3-5 minutes up to a total dose of 3 mg.
Dopamine: Second-line drug for symptomatic bradycardia when atropine is not effective. Dosage is 5-20 micrograms/kg/min infusion.
Epinephrine: Can be used as an equal alternative to dopamine when atropine is not effective. Dosage is 2-10 micrograms/min.
Bradycardia Algorithm
The decision point for ACLS intervention in the bradycardia algorithm is determination of adequate perfusion. For the patient with adequate perfusion, observe and monitor the patient. If the patient has poor perfusion, preparation for transcutaneous pacing should be initiated, and an assessment of contributing causes (H’s and T’s) should be carried out.
Click below to view the bradycardia algorithm diagram. When finished, click again to close the diagram.
Bradycardia Algorithm Diagram
or Download the High Resolution PDF Here. (This will open in another window.)
Transcutaneous pacing (TCP)
Preparation for TCP takes place as atropine is being given. If atropine fails to alleviate symptomatic bradycardia, TCP is initiated. Ideally, the patient receives sedation prior to pacing, but if the patient is deteriorating rapidly, it may be necessary to start TCP prior to sedation.
For the patient with symptomatic bradycardia with signs of poor perfusion, transcutaneous pacing is the treatment of choice.
Do not delay TCP for the patient with symptomatic bradycardia with signs of poor perfusion. The starting rate for TCP is 60-80/min and adjust up or down based on the patient’s clinical response. The dose for pacing is set at 2mA (milliamperes) above the dose that produces observed capture.
TCP is contraindicated in the patient with hypothermia and is not a recommended treatment for asystole.
Do not use a carotid pulse check for the assessment of circulation as TCP can create muscular movements that may feel like a carotid pulse. Assess circulation using the femoral pulse.
Identification of contributing factors for symptomatic bradycardia should be considered throughout the ACLS protocol since reversing of the cause will likely return the patient to a state of adequate perfusion.
Top Questions Asked on This Page
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Q: Should I use atropine in all cases of symptomatic bradycardia regardless of the level of block? The prep test for AHA ACLS seems to support giving atropine initially in symptomatic second-degree block type II, but not for complete block.
A: There are a couple of things to mention here. First, atropine may be used for any type of block but may negatively affect outcomes if the bradycardia is being caused by myocardial infarction.
This negative effect may occur because atropine increases the heart rate and myocardial oxygen demand. In the case of bradycardia caused by MI, it would be safer to transcutaneous pace (TCP) at a rate of 60 and move toward some type of cardiac intervention. You should use the 12 lead ECG to help determine MI. This will help determine if atropine may exacerbate the patient’s condition. If the patient has severe symptoms, you should not delay transcutaneous pacing (TCP).
You will usually have time to try atropine as you prepare for TCP.
Second, AHA states “For Mobitz II and complete block (3rd Degree block), atropine should not be relied upon.” This does not mean that it is contraindicated. It just means that it should not be relied upon because there is a good chance that it will not work.
It may not work because atropine blocks the action of the vagus nerve. Atropine works at the SA and AV node through its effect on the vagus nerve, and since conduction abnormalities associated with 2nd-degree block type II and 3rd-degree heart block are below (distal) the site of action for atropine, the drug will typically have an insignificant effect.
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Q: Why is pacing contraindicated in hypothermia?
A: Bradycardia may be physiologic in the hypothermic patient. This type of bradycardia is an appropriate response to the decreased metabolic rate that normally occurs with hypothermia.
Also the hypothermic ventricle is more prone to fibrillation with any sort of irritation. Thus the irritation of TCP could induce VF. Once the hypothermic ventricle begins to fibrillate, it is more resistant to defibrillation. Warm the patient and then treat any remaining arrhythmias.
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Q: What is TCP?
A: TCP means transcutaneous pacing.
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Q: What is chemical pacing?
A: Chemical pacing is when IV medications (epinephrine or dopamine) are used to increase the heart rate rather than the transcutaneous pacing which uses electricity to increase the heart rate.
smlitzen says
What would be recommended for sedation prior to pacing? Thank you!
Jeff with admin. says
A recent study concluded that propofol, methohexital, thiopentone and etomidate all seem to be good choices.
Kind regards,
Jeff
Wendy says
how will we categorize stable and unstable patients? what are the parameters?
Jeff with admin. says
Hypotension, chest pain, signs of shock, SOA, altered mental status, weakness, fatigue, and syncope are all signs and symptoms of a patient who is unstable/symptomatic.
Kind regards,
Jeff
Grey says
What does SOA stand for?
Jeff with admin. says
SOA means “short of air.” Basically, short of air and short of breath are interchangeable. It just depends upon what your hospital accepts as a use of acceptable abbreviation.
Kind regards,
Jeff
lilpeanut226 says
I just have to say this is the BEST EMS sight I have ever been on. Very simple to use and very nicely put together. Organized and easy to find what you need information on. it doesn’t overload you on detailed information that racks your brain. You should really think about doing a PALS and ITLS websight. Thank you so much for a great place to learn…
Bonnie says
Agree! Thank you so much. Very understandable, concise explanations. What a gift!
itsKevin says
Why do some resources(AHA) state that you can give atropine in second degree type 2 and Third degree block? Then in the same resource it states because of lack of vagal innervation it will not work and possibly make a block worse. Doesn’t seem very cut and dry to me. Which is correct. Let me ask you. If you were taking care of a patient in complete heart block would you attempt to use atropine while waiting for TCP/chronotropes? Honestly I am sure it wouldn’t take any longer to start TCP/chronotropes than give atropine but lets just say that for some reason that your one crash cart is unavailable and you are awaiting another defibrillator/pacer from another floor in the hospital.
Thanks,
Kevin
Chris with admin. says
I think the reason they do this is because there is not enough evidence and
the recommendations are based on expert consensus. If a patient is having an
MI and you increase their heart rate, you may make the MI worse. If it was
me, I would go to pacing if it was readily available. A lot of folks would
probably push atropine. I bet most cardiologists would opt for pacing.
Kind regards, Chris
Jessica says
In my ACLS review they stated, “IV epi and IV dopamine are preferred over transcutaneous pacing when Atropine is ineffective”. I’m confused, because everything else I read seems to indicate you should move right to TCP if Atropine is ineffective. Can you clarify the recommendations?
Jeff with admin. says
Here is what the AHA ACLS provider manual states pg. 163:
“For symptomatic bradycardia, the AHA now recommends IV infusion of chronotropic agents (dopamine or epinephrine) as an equally effective alternative to external transcutaneous pacing when atropine is ineffective.
The wording “equally effective alternative” would be the most important language in the statement. It does not say “preferred.” I would say that the statement that epinephrine and dopamine would be “preferred” would be incorrect.
Kind regards,
Jeff
monita says
can you use atropine for bradycardia in the setting of Mobitz I and Mobitz II blocks?
Jeff with admin. says
Atropine can be used but it may be ineffective because atropine’s affect is at the SA node. These blocks occur at the AV node.
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 in with 3rd degree block unless they are unstable and you delay pacing to give atropine.
However, the major reason why you would not want to give it is because of the risk of worsening already existing myocardial ischemia as is common with a new onset of 2nd degree block Type 2 or complete heart block.
Kind regards,
Jeff
Paul says
If the patient is severely symptomatic do you forgo atropine in favor of TCP? or is it always indicated to try atropine first. Not asking in regards to “real life” scenarios but more of a “how to answer a test question” scenario.
Jeff with admin. says
In the case of a severely symptomatic patient, the use of TCP should not be delayed. If you can give atropine without delaying the use of TCP it is ok to give it. for a scenario, I would say something like “While the TCP is being prepared, I am going to give 0.5mg of atropine.”
Kind regards,
Jeff
mohaneje3 says
What is tcp
Jeff with admin. says
TCP means transcutaneous pacing.
Kind regards,
Jeff
DsT says
In regards to Dopamine; In one of the previous ACLS textbooks there was mention of the 2-5 mcg dose was no longer recommended due to lack of data, etc. It advised that the new dose range is 5-20 mcg/kg/min. In the newer texts, I no longer find a reference of this, and the recommended dose continues to be 2-20 mcg, even though we will not be using the 2-5 mcg range.
Any insight of an upcoming change?
Thanks!
Jeff with admin. says
Since at least 2008, the dosing recommendation for chemical pacing using bradycardia has been 2-10 mcg/kg/min. I am not aware of any changes from the 2-10 mcg/kg/min dosing.
Kind regards,
Jeff
Kenny says
what is the max milla amp u can go up to in order to try and achieve capture?
Jeff with admin. says
There is really no max. You keep going up until you get capture and then if your machine allows, you go up 2 milliamperes.
It is interesting you asked that question. I actually discussed this very thing yesterday with a cardiologist at the Hospital I work at.
Usually capture will occur between 30-50 milliamperes. You can go higher if needed.
Kind regards,
Jeff
Jessica says
Why is it recommended to increase 2 mA following 100 % capture. In Aehlert’s 2012 ACLS study guide it simply just states doing so, without explanation. My guess is to maintain threshold?
Thanks!
Jeff with admin. says
This practice is recommended to ensure that the threshold of capture is met and exceeded. Just for your own information, many pacemakers go in increments in 5 or 10 mA, and you may have to set the pacemaker at 5 to 10 mA above capture.
Kind regards,
Jeff
Mateo says
What if you had a sinus brady STEMI or a bradycardic rhythm that showed ST elevation on a 3 lead monitor? I have always heard that Pacing a STEMI could actually cause too much stress to the already starving for oxygen heart and put the patient into arrest. Is this true or fallacy?
Jeff with admin. says
If you have symptomatic bradycardia with STEMI, you would be ok to pace but keep the rate at around 60 or less. The object would be to keep the rate as low as possible to maintain adequate perfusion. Any intervention may increase oxygen consumption of the heart. This type of patient should receive coronary intervention as soon as possible. You would also start anticoagulation therapy, control pain with nitro and morphine, and provide coronary intervention as soon as possible.
Kind regards,
Jeff
jprosen1 says
If the TCP is not available, do you keep giving the atropine up to 3 mg or go for the pressors.
Jeff with admin. says
If TCP is not available you would attempt chemical pacing with a epinephrine drip or a dopamine drip according to the bradycardia AHA ACLS protocol.
You could continue use of atropine along with the drip if the rate does not improve.
Kind regards,
Jeff
HAI says
hi
I want to know if you continue with Atropine when it has has failed to alleviate symptomatic bradycardia and TCP has been initiated.
Jeff with admin. says
If you have initiated TCP there would be no need to continue with the use of atropine.
Kind regards,
Jeff
Corey says
When do you pace? do you pace for every kind of bradychardia when the heart rate is low, or only certain ones?
Jeff with admin. says
You will use transcutaneous pacing if the patient has symptomatic bradycardia and atropine has not been effective for improving the heart rate and symptoms.
Any am symptomatic bradycardia can be paced.
Kind regards,
Jeff
Malachi Shane Cole says
At what point during severe bradycardia do you start CPR? Is it always once you lose a pulse or would you start it at say 15 or 20 bpm? Just curious because I was told the other day by a nurse it was policy at her hospital to start CPR if atropine is not successful and the HR dropped below 20 BPM until epi or dop drips arrive or TCP arrives. Thank you
Jeff with admin. says
AHA has no specific set pulse at which to start CPR for the bradycardia algorithm. Clinical judgment of the situation should dictate what interventions are performed. Of primary importance is adequate perfusion of the vital organs. Signs and symptoms should direct your course of action.
The policy that you mention sounds reasonable. If the patient is having serious symptoms, atropine has failed, and you do not have the means to pace whether with drugs or with electricity then CPR could be warranted.
If you have the means to pace that would be the next appropriate intervention.
Kind regards,
Jeff
Dr.Punitha says
I had the same doubt in my mind. Got it clarified with your answer . Thank you