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In this lesson, we're going to cover tachycardia, including some things to be aware of when dealing with tachycardic patients, types of tachycardia, underlying causes, and some information on the best courses of treatment to resolve that patient's tachycardia.
Tachycardias can be both stable and unstable. In adults, tachycardia is technically defined as heart rates greater than 100 beats per minute.
Types of Tachycardia
Common types of tachycardia include:
- Atrial fibrillation
- Atrial flutter
- Sinus tachycardia
- Supraventricular tachycardia (SVT)
- Ventricular tachycardia
- Ventricular fibrillation
Causes of Tachycardia
Many things can cause tachycardia, including semi-benign causes such as fever or stress. More serious causes of tachycardia include:
- Shock
- Medications
- Metabolic dysfunction
- Hypoxemia
- Damage to the heart muscle
Perfusion problems may develop when the patient's heart beats too fast and the ventricles are not able to fill properly with blood, which is technically called ejection fraction compromise.
This occurs due to a lack of preload before the heart fully contracts and can cause a decrease in cardiac output and poor perfusion, which can lead to hemodynamic instability.
Pro Tip #1: It's important to quickly assess a tachycardic patient and determine if their signs and symptoms are the result of the tachycardia. It's equally important to find underlying causes of the tachycardia and treat those causes.
Patients with heart rates between 100 and 150 beats per minute will rarely have symptoms related to the tachycardia. Rather, symptoms in this range are normally the result of other medical issues.
However, the higher the heart rate, the more likely that the tachycardia is the culprit of the patient's symptoms. For this reason, a thorough primary and secondary survey will help you properly assess the patient's condition.
Identifying and Treating Tachycardia
When you have a patient with tachycardia, the first step is to identify whether or not the patient is stable. A stable patient has no serious signs or symptoms as a result of the increased heart rate, such as:
- Altered mental status
- Chest pain
- Hypotension
- Other signs of shock
For stable patients, you should do the following:
- Check their vital signs
- Monitor their oxygen saturation
- Give oxygen as needed
- Get an ECG or 12 lead
- Identify their heart rhythm
- Start an IV
Pro Tip #2: If you determine a patient to be unstable, as in one that has some of those more serious symptoms listed in the list above, synchronized cardioversion is the treatment of choice and should be done immediately.
Remember, electrical therapy can cause some discomfort. If time permits and the patient is conscious, consider sedation. But if time does not permit, you may need to defibrillate regardless of sedation.
If you have a patient with no pulse, treat this rhythm as if it was ventricular fibrillation (VFib) and follow the pulseless arrest algorithm.
Pro Tip #3: The first step to identifying tachycardic heart rhythms is to determine if the QRS complexes are wide or narrow. Wide QRS complexes are .12 seconds or greater, while narrow QRS complexes are less than .12 seconds.
Narrow complex tachycardias typically originate above the ventricles. While wide complex tachycardias typically originate in the ventricles and pose a higher risk of deteriorating into cardiac arrest.
For patients with regular narrow complex stable tachycardia:
- It's appropriate to first attempt vagal maneuvers.
- If that doesn't work, give adenosine at 6mg via rapid IV push.
- If the patient does not convert and remains stable, give a second dose of adenosine at 12mg via rapid IV push.
Pro Tip #4: While you understand the side effects of adenosine, your patient probably does not. So, after administering the medication, tell them they may get a feeling of breathlessness, a flushed feeling, or the feeling that their heart is skipping a beat. And let them know these side effects will pass quickly.
For stable patients with irregular narrow complex QRS tachycardia, it's probably atrial fibrillation (AFib), atrial flutter (AF), or a multi-focal atrial tachycardia and would require expert consultation to treat.
For stable patients with regular or irregular wide complex QRS tachycardia, this would usually be treated with antiarrhythmics like procainamide or amiodarone and will also require expert consultation.
It's also important to remember that management and treatment of wide complex stable tachycardia requires advanced knowledge of ECG rhythm interpretation and antiarrhythmic therapy.
