If you’ve ever found yourself facing a fast heartbeat on a monitor during an emergency, you know how important it is to act fast—but also smart. Tachycardia can quickly worsen, and knowing precisely what to do next can be the difference between stabilization and deterioration. That’s where the ACLS Tachycardia Algorithm comes into play, a step-by-step approach according to the American Heart Association (AHA) guidelines to guide your decisions when every second counts.
Whether you’re a nurse, EMT, paramedic, or physician, knowing this algorithm equips you to respond promptly, safely, and effectively when a patient presents with a high heart rate and a pulse. In this article, you will find a comprehensive, guided walkthrough of the Tachycardia ACLS Algorithm. We’ll also discuss essential medications, electrical therapy, and some common pitfalls to avoid.
Ready to take your emergency response skills to the next level? Let’s dive in.
By definition, tachycardia is a heart rate greater than 100 beats per minute. However, in ACLS, it’s not just a number; it’s a potentially life-threatening condition that requires immediate intervention if the patient is symptomatic. The ACLS Tachycardia Algorithm focuses only on managing tachycardias with a pulse, enabling you to recognize whether the rhythm is stable or unstable and make the appropriate intervention.
According to the study conducted by Gopinathannair and Olshansky, effective management of tachycardia is crucial, as persistently elevated heart rates can lead to tachycardia-mediated cardiomyopathy. Tachycardia is not just about treating a fast heart rate; it is about finding out what is causing it, whether the patient is in danger, and the correct use of either electrical or pharmacological intervention. The algorithm provides a transparent road map so you aren’t second-guessing when it matters the most.
Let’s break down the core of the algorithm step by step:
01.
Are they experiencing symptoms like low blood pressure, chest pain, altered mental status, or signs of shock? If yes, they’re unstable.
02.
03.
04.
05.
Have defibrillation and airway management supplies ready
06.
Use the Hs and Ts approach (Hypoxia, Hypovolemia, Tension Pneumothorax, etc.)
When you’re standing at the bedside, and a patient’s heart rate is racing, you always want to determine: Are they stable or unstable? That single choice establishes the tone for all that comes next. And it’s not just a clinical call — it’s a life-saving judgment.
Let’s start with the basics. Not every fast heart rate needs immediate emergency intervention, but some do. So, how do you distinguish between the two? Look closely for signs that the heart’s rapid rhythm affects the patient’s ability to maintain adequate circulation. These red flags scream “unstable”:
If any of those symptoms are present, you’re not just treating a number but a potentially crashing patient. That’s when you reach for the synchronized cardioversion button.
But if your patient is awake, has good blood pressure, and is not in distress, then congratulations—they are stable. This buys you some time so you can manage the rhythm more conservatively, often with medication and ongoing monitoring.
In simple terms:
Unstable = Electricity
Stable = Drugs + Watchful Monitoring
So, you’ve identified an unstable patient. What now?
Synchronized cardioversion is your go-to move here. It’s a controlled electrical shock that’s timed (or “synced”) to the R-wave of the ECG to reset the heart’s rhythm without sending it into something worse, like ventricular fibrillation.
Here’s what you need to know about the energy levels:
If the first shock doesn’t work? Don’t panic—increase the energy and try again.
If you deliver a shock unsynchronized, you can get into dangerous territory. And don’t forget sedation. If the patient is awake, being shocked is painful. If you have time and your patient is conscious, a quick sedative like midazolam can make it a more tolerable experience.
While preparing for cardioversion or starting medication, don’t overlook the simple but essential things:
Even if the situation seems under control, always prepare for escalation—because sometimes, it does.
If your patient is stable, medications are the best shot you have at slowing or converting the rhythm. However, you must choose the right one based on what you see on the ECG.
Here’s a breakdown of the core ACLS drugs you should have on your radar:
|
Medication |
When to Use It |
Dosage |
|
Adenosine |
Regular narrow-complex SVT |
6 mg IV push → repeat with 12 mg |
|
Amiodarone |
Stable VT with a pulse |
150 mg IV over 10 minutes |
|
Procainamide |
Wide-complex tachycardia |
20–50 mg/min until controlled |
|
Sotalol |
Alternative for wide-complex VT |
1.5 mg/kg IV over 5 minutes |
A word of caution: Never administer adenosine if you’re not sure the rhythm is regular or if you are dealing with irregular wide-complex tachycardia (e.g., pre-excited atrial fibrillation). It can make things even worse — quickly.
Another tip: If you’re unsure whether the rhythm is ventricular or supraventricular in origin, treat it as if it were ventricular until proven otherwise. It’s the safer route.
Even experienced providers can make mistakes in high-stress cardiac emergencies. Here are the most common errors to avoid in ACLS management of tachycardia with a pulse:
Knowing the Tachycardia ACLS Algorithm isn’t just about memorizing steps—it’s about staying calm, thinking fast, and taking the right action when every second matters. Real readiness comes from hands-on training, consistent practice, and staying updated with the latest American Heart Association (AHA) guidelines. If it has been a while since your last ACLS course, now’s the time to revisit and re-hone those crucial skills. Don’t wait for an emergency to discover you’re out of practice. Get ACLS certified with Bayside CPR and earn more than a certification — get the confidence to save a life.
The first-line treatment for unstable tachycardia in ACLS is synchronized cardioversion. This is used when the patient has a pulse but shows signs of instability like hypotension, altered mental status, or chest pain.
CPR is only given for pulseless ventricular tachycardia (VT). If the patient has a pulse but is unstable, synchronized cardioversion is indicated instead of CPR.
Ventricular tachycardia is considered significant when there are three or more consecutive ventricular beats at a rate of over 100 beats per minute. It’s a serious rhythm that requires prompt assessment.
ACLS recommends antiarrhythmic drugs like amiodarone for stable VT with a pulse. Synchronized cardioversion is indicated for unstable VT with a pulse. If the VT is pulseless, follow the cardiac arrest algorithm with CPR and defibrillation.
For synchronized cardioversion of unstable tachycardia, the recommended energy dose typically starts at 50–100 joules for narrow complex and 100 joules or more for wide complex tachycardia, depending on the device and patient response.
