Tachycardia/tachyarrhythmia is defined as a rhythm with a heart rate greater than 100 bpm.
An unstable tachycardia exists when cardiac output is reduced to the point of causing serious signs and symptoms.
Serious signs and symptoms commonly seen with unstable tachycardia are: chest pain, signs of shock, SOA (short of air), altered mental status, weakness, fatigue, and syncope.
One important question you may want to ask is: “Are the symptoms being caused by the tachycardia?” If the symptoms are being caused by the tachycardia treat the tachycardia.
Causes
There are many causes of both stable and unstable tachycardia and appropriate treatment within the ACLS framework requires identification of causative factors. Before initiating invasive interventions, reversible causes should be identified and treated.
The most common causes of tachycardia that should be treated outside of the ACLS tachycardia algorithm are dehydration, hypoxia, fever, and sepsis. There may be other contributing causes and review of the H’s and T’s of ACLS should take place as needed.
Click below to view the H and T’s table. When done click again to close the diagram.
H's and T's Table
Administration of OXYGEN and NORMAL SALINE are of primary importance for the treatment of causative factors of sinus tachycardia and should be considered prior to ACLS intervention.
Once these causative factors have been ruled out or treated, invasive treatment using the ACLS tachycardia algorithm should be implemented.
Associated Rhythms
There are several rhythms that are frequently associated with stable and unstable tachycardia these rhythms include:
- Supraventricular tachycardia (SVT)
- Atrial fibrillation
- Atrial flutter
- Monomorphic VT
- Polymorphic VT
- Wide-complex tachycardia of uncertain type
ACLS Treatment for Tachycardia
Click below to view the tachycardia algorithm diagram. When done click again to close the diagram. Tachycardia Algorithm Diagram.
The first question that should be asked when initiating the ACLS tachycardia algorithm is: “Is the patient stable or unstable?” The answer to this question will determine which path of the tachycardia algorithm is executed.
Unstable Tachycardia
Patients with unstable tachycardia should be treated immediately with synchronized cardioversion. If a pulseless tachycardia is present patients should be treated using the cardiac arrest algorithm.
The initial recommended synchronized cardioversion voltage doses are as follows:
- narrow regular: 50-100 J; i.e., SVT and atrial flutter
- Narrow irregular: 120-200 J biphasic or 200 J monophasic; i.e., atrial fibrillation
- Wide regular: 100 J; i.e., monomorphic VT
- Wide irregular: defibrillation dose (not synchronized)
Stable Tachycardia
Patients with stable tachycardia are treated based upon whether they have a narrow or wide QRS complex. The following flow diagram shows the treatment regimen for stable tachycardia with narrow and wide QRS complex.
- Stable (narrow QRS complex) → vagal maneuvers → adenosine (if regular) → beta-blocker/calcium channel blocker → get an expert
- Stable (wide/regular/monomorphic) → adenosine → consider antiarrhythmic infusion → get an expert
Carol Wollenstein says
I’m confused by the idea of treating SVT with cardioversion. Couldn’t an SVT actually be sinus tachycardia? I did not think that was a shockable rhythm. I would think there was a very large risk.
ACLS says
The treatment of SVT with cardioversion is rare. Vagal maneuvers and rapid IV push adenosine have a very high conversion rate for SVT.
However, elective cardioversion for superventricular tachycardia can be performed safely. You would need to ensure that the cardioversion is synchronized and you use the appropriate shock dose. There is minimal risk for synchronize cardioversion using the appropriate starting shock dose of 50J.
Kaitlyn Uhrig says
If an unstable polymorphic VT is displayed, it states to shock at a defibrillation dose. (My protocol states defib dose is automatically 360) but my question is would you shock at 100 (cardioversion dose) or the defib dose -per ACLS would be 200?
ACLS says
You would shock at the defibrillation dose. Different protocols may have different starting doses. AHA guidelines recommend a starting dose of 120-200 J.
Kind regards,
Jeff
Mustafa says
Hi
If patient stable with AF fast what is best drug..??
If patient stable with VT what is best drug .. ..??
Thx
ACLS says
There are a lot of variables that would affect the answer to your questions. Pre-existing conditions such as renal failure and heart failure would affect the choice made.
The underlying cause of each of these conditions would also need to be evaluated prior to choosing an intervention or medication.
There is no simple best drug for either a fib with RVR or or stable VT and both would require prior expert consultation. Both of these would also be beyond the scope of ACLS.
Kind regards,
Jeff
Kkress says
Afib rvr/a flutter is usually treated with calcium channel blockers like diltiazem, VT w/pulse is usually treated with Amiodarone or Lidocaine
Andrea Zimroth says
Is there a certain amount if time between syncronized shocks?
ACLS says
There is no set amount of time that is designated for waiting before providing additional synchronized shocks.
The reason why there is a two minute period between each shock for cardiac arrest is to ensure adequate circulation with CPR.
When dealing with tachycardia with a pulse, you already have circulation and therefore the time period between shocks is not as important.
Kind regards,
Jeff