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.
raymond says
I am considering in taking the ACLS course. This information of yours is really help full. More power to you.
mag says
I can’t even get the heart specialist nor the internal medicine doctor i see to recognize my slowed heart beat. They just keep ignoring my complaints. I don’t know what else to do, because i have tried several doctors, who all ignore my symptoms. I feel bad. Why are they letting my health complaints go?
Jeff with admin. says
Hi Mag,
This site is really not the place to answer medical questions. It is a training website for advanced cardiac life support. I would find another physician who will listen. Kind regards, Jeff
muhammad abdullah says
perfectly explained
Danielle Gullo says
This site is the best, simplified rationales and user friendly. How selfless of you to take the time to do this for others. Thank you so much. I will direct all my friends to your site for ACLS preparation. I’m sure I will continue to refer to it to keep my assessments key and interventions appropriate. Thanks again!!! You Rock!
Courtney Bishop says
Haha danielle, I agree. It’s crazy we are both looking at the same site!
Lee Jay says
This was extremely helpful and easy to understand.. This should be kept updated because I will definitely be checking in again.. Thank you for the help and assistance! Much appreciated! Lotsa love!
LORINDA SHAW says
why is TCP not recommended for hypothermia and asystole?
Jeff with admin. says
It has repeatedly been shown to be ineffective to achieve ROSC with PEA and Asystole.
NASSER HATTAB says
clear, easy and helpful,Thanks a lot!
Vivian Trussell says
Great site in perparing for acls.
Thank you very much
CHRISTOPHER ASAPOKHAI says
ECG made easy. Thank you. I love u.
Jacki Allison says
Pray for me, I start the Acls tommorw 3-16 and test on Sunday Mar 18. I seem to have difficulties (especially with recall) with the megacode. Thanks. Jacki
T.Meyer says
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Rosalie Mora says
Great website I have learned so much in such a short amount of time.I only have three days to prepare, wish me luck.
armando fernandez says
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Diego Carta says
I’m so glad I found this site. I’ve only been on for one hour and I’ve learned (caught on to) a lot more than in class! Great work, keep it up!
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