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
-
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.
-
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.
-
Q: What is TCP?
A: TCP means transcutaneous pacing.
-
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.
Vivire says
I had a patient, symptomatic bradycardia. Fully conscious and alert,talking,not in respiratory distress BP 100/80 (he known hypertensive). And had complete heart block. He presented with multiple syncopal attack.he had 2 episodes of syncope and near syncope in ED (witnessed). My question is, between chemical pacing and TCP, which is superior /preferred . Can we do simultaneous pacing? (Both chemical and tcp). Thank you
Vivire says
P/s .patient 3rd degree block. Rate 30.
Is there any studies conducted for chemical pacing vs TCP? (Couldnt find online)
Jeff with admin. says
PubMed would be the place to look for these types of studies. You would be wading through a lot of literature to get your answers. This is why AHA does a lot of this work for us, and then develops guidelines. AHA makes their guidelines after a regular and thorough review of the medical literature. The AHA now states that chemical pacing is just as effective as an alternative to TCP. Personally, I like electrical pacing. It seems to me like it can be more closely regulated and easily discontinued. However, their literature review seems to indicate that chemical pacing is just as good.
In the situation you experienced something like demand pacing for a heart rate less than 50 or 60 many have been the right way to go especially with complete block.
If you were to attempt chemical pacing, you would probably want to infuse to maintain a HR greater than 60 or 70 and keep the patient free of symptoms until a pacemaker could be placed.
I’m not an expert in this area, and I imagine that even most internal med residents and such would get with a cardiologist rather quickly on cases like this.
Hope this helps.
Kind regards,
Jeff
fitri says
i had a patient with blackout,airway n breathing was clear, BP 90/60,HR 40x,what should i do first?sugestion please..i decided to iv line loading RL n epineprine 0,5 im is that correct?
regards
Jeff with admin. says
Considering that the Heart rate was 40 and the patient was symptomatic AHA ACLS guidelines would have directed toward IV, EKG, atropine 0.5mg IV push. You would also want to immediately start looking for the cause of the bradycardia and also ensure that the bradycardia was the cause of the blackout.
Kind regards,
Jeff
Jean says
If pt fails with atropine n T C P which is first choice dopamine
or adrenaline
Jeff with admin. says
Either is considered equally effective and either can be used as an acceptable alternative to TCP.
Kind regards,
Jeff
Nicola says
Today we witnessed a cardiac arrest where the patient was experiencing a palpable beat centrally at an irregular rate of approximately 6 per minute; for a sustained period of approximately 25 minutes. Could you please tell me if there is a minimum heart rate for atropine to be successful in raising the heart rate?
Thank you!
Jeff with admin. says
You cannot have cardiac arrest and bradycardia at the same time. Most likely, this irregular beat was chaotic and should not be considered a perfusion generating pulse.
If the patient was in cardiac arrest then atropine would not be appropriate. By definition cardiac arrest means that the heart is no longer providing effective perfusion to the vital organs. CPR would be the appropriate action in this case. It is not uncommon to think that a pulse if felt or to feel a random pulse. The fall back would be to obtain a peripheral blood pressure. If you cannot obtain a blood pressure then you have no effective perfusion. In this case, CPR Should be performed and the pulseless arrest algorithm should be used.
You also would need to look for the cause of this arrest. Understanding why the arrest is very important so that any reversible causes can be addressed.
Kind regards,
Jeff
melsa says
is there any limit for the heart rate in asymptomatic sinus bradicardiab that should given atropine 0,5 mg? thx
Jeff with admin. says
If a patient is asymptomatic with a heart rate of 30 and they are not an athlete, it would be surprising. Atropine should be used when a pt. has symptoms. If the HR is low and there is no reason and the patient is asymptomatic, they should probably should have a cardiology evaluation. Also, they probably would become symptomatic with activity.
Anyway, if they are severely bradycardic but asymptomatic, they should be evaluated by a cardiologist. I do not think it would be recommended to use atropine unless they are symptomatic.
Kind regards,
Jeff
Pacer says
We were wondering if pacing is less invasive than IO atropine. As in you can not get an IV not serious signs and systems but deteriorating. Would it be better to pace or IO atropine.
Jeff with admin. says
IO is really only used in emergencies. If the above scenario occurred in an ER, I think that most ER physicians would get a quick central line in if possible. If this were not possible, I think that most ER physicians would go with TCP and then get a line once pacing was initiated. Pacing is very non-invasive with minimal complications, and it can be discontinued easily.
Kind regards,
Jeff
gACLS says
I see since the last time I took ACLS that Isuprel is no longer on the bradycardia algorithm. Has it been removed?
gACLS says
Also I was looking for something on transplanted hearts. Are there any exceptions to the algorithms for transplanted hearts?
Jeff with admin. says
I could not find anything stating that the treatment of patients with heart transplants would be any differently during cardiac arrest.
I did find this article that speaks specifically to CPR and this issue.
I have sent an e-mail to my brother who has more experience in this area. If I find out any other information, I will let you know.
Kind regards,
Jeff
Jeff with admin. says
Although Isoprel is no longer a first-line medication in the ACLS bradycardia algorithm, it is still can be used. Here is a quote from AHA 2010 guidelines on this issue:
“Although not first-line agents for treatment of symptomatic bradycardia, dopamine, epinephrine, and isoproterenol are alternatives when a bradyarrhythmia is unresponsive to or inappropriate for treatment with atropine, or as a temporizing measure while awaiting the availability of a pacemaker. Alternative drugs may also be appropriate in special circumstances such as the overdose of a β-blocker or calcium channel blocker.” Here is the link to the AHA article.
Kind regards,
Jeff
Carmesuze Joseph says
I have such a hard time differentiate between a complete blocks ,Sinus exit block and sinus pause Cant get them straight…..please help!
Jeff with admin. says
The easiest why I explain it is as follows.
In a 3rd degree heart block is a persistent rhythm having P waves and QRS complexes that are not associated with one another. Further, the P waves march out with one another as do the QRS complexes.
Sinus Arrest/Pause is not a persistent rhythm/ It’s intermittent. P waves and QRSs are associated with one another. i.e you have a PR interval except for when you have sinus arrest, then you just have no electrical impulse for a beat.
Does that make since. Here is a great sight to view and study 12 lead ECGs
Hope this helps.
Kind regards,
Chris
Tgrieser says
I have such a hard time with the blocks! Cant get them straight…..please help!
Jeff with admin. says
There are a series of webpages on this website regarding blocks that will be considerable help to you. You can find them here in the bradyarrhythmias section.
Kind regards,
Jeff
nizam says
There are some statement said, we cannot give IV atropine less than 0.5mg. it may cause paradoxically result in further slowing the heart rate. Can you elaborate more thank you
dalal alhasan says
Hello,
1.do we have to give atropine to all symptomatic bradycardia patients even if mobtiz II and 3rd degree heart blocks? if no what should bemy first action?
2. in mobtiz II or 3rd degree heart block and un available TCP is it safe to give dopamine or adrenaline?
Jeff with admin. says
1. “Do not rely on atropine in Mobitz type II or 3rd degree AV Block or in patient with 3rd degree AV block with a new wide QRS complex.”
Therefore if a patient is unstable, in this situation, it is ok to go to electrical pacing.
2. Yes, dopamine and epinephrine infusions are acceptable replacements for electrical pacing.
Kind regards,
Jeff
Jacqueline Watson says
Excellent,extremely beneficial
chibi says
hi, im just confused, if patient is with stable bradycardia, should the patient still be given the first line drug atropine or the dopamine/ epinephrine? or should the patient be monitored and observed only?
Jeff with admin. says
For the patient with stable bradycardia, the patient would be monitored and observed. Common practice would be to admit the patient to an ICU or telemetry unit and consult with cardiology.
Kind regards,
Jeff
Blazegirl1 says
Why is pacing contraindicated in hypothermia?
Great site…huge help in studying for recert!!
I’m a Navy veteran myself, so thank you for your service and sacrifice!
Jeff with admin. says
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.
Kind regards,
Jeff
riyas says
How long we should wait and see whether 1st line management is working. ….and before giving atropine can we give a sympathetic stimulation and see whether it’s increasing or not….and my another question is I had seen lot of cases with patient who is coming with heart rate of 40 and some odd , so that occasion is it mandator to give some intervention especially if patient is under spinal anaesthesia
Jeff with admin. says
Atropine should have it affect within 30 seconds after administration. If you do not see an improvement in the patients condition within 1-2 minutes max., You should through the bradycardia algorithm. Atropine blocks the action of the vagus nerve, a part of the parasympathetic system of the heart whose main action is to decrease heart rate. You should see a direct effect on the rate of the heart. If the heart rate does not improve and the patients symptoms do not improve, you should move on.
I do not understand what you are trying to ask in your second question.
Kind regards,
Jeff