Two keys to managing patients with unstable tachycardia are, first, quickly recognizing that the patient has significant symptoms and is unstable, and second, quickly recognizing that the patient's signs and symptoms are caused by the tachycardia. You need to decide if the tachycardia is producing the hemodynamic instability and serious signs and symptoms or if the signs and symptoms are producing the tachycardia—for example, the pain and distress of an acute MI could be causing the tachycardia. Making this decision can be difficult. Generally, a heart rate between 100 bpm and approximately 130 bpm is usually caused by an underlying process that is represented as sinus tachycardia (see Stable Tachycardia module for more information on sinus tachycardia). Heart rates > 150 bpm may be symptomatic. The higher the rate, the more likely the symptoms are a result of the tachycardia. Underlying heart disease or other problems can cause symptoms at lower heart rates. Keep in mind the following considerations:
The ACLS Tachycardia Algorithm is organized around the following four questions:
If the patient does not have a pulse and his or her rhythm is a tachycardia, follow the ACLS Pulseless Arrest Algorithm.
If a pulse is present, answer these three questions to help determine treatment options for tachycardia:
Assess the patient using the primary and secondary surveys:
Look for altered mental status, ongoing chest pain, hypotension, or other signs of shock.
Remember:rate-related symptoms are uncommon if heart rate is less than 150 bpm.
If the signs and symptoms continue after you have given oxygen and supported the airway and circulation AND if significant symptoms are due to the tachycardia, then the tachycardia is UNSTABLE and immediate cardioversion is indicated.
If you determine that the patient has an unstable tachycardia, perform immediate synchronized cardioversion.
If you determine that the patient has a stable tachycardia, start an IV and obtain a 12-lead ECG
For a patient with a stable tachycardia, decide if the QRS complex is wide or narrow and if the rhythm is regular.
|Narrow (< 0.12 sec) QRS complex||Try vagal maneuvers|
|Regular rhythm||Give adenosine 6 mg rapid IV push|
|Repeat 12 mg dose once if necessary|
Does the patient's rhythm convert? If it does, it was probably reentry supraventricular tachycardia. At this point you watch for a recurrence. If the tachycardia resumes, treat with adenosine or longer-acting AV nodal blocking agents, such as diltiazem or beta-blockers.
|Narrow (< 0.12 sec) QRS complex||Consider expert consultation|
|Irregular rhythm||Control patient's rate with diltiazem or beta-blockers. Use beta-blockers with caution for patients with pulmonary disease or congestive heart failure.|
If the rhythm pattern is irregular narrow-complex tachycardia, it is probably atrial fibrillation, possible atrial flutter, or multi-focal atrial tachycardia.
|Wide (< 0.12 sec) QRS complex||Expert consultation is advised.|
|Regular rhythm||Expert consultation advised.|
|If patient is in ventricular tachycardia or uncertain rhythm||Amiodarone 150 mg IV over 10 min; repeat as needed to maximum dose of 2.2 g in 24 hours Prepare for elective synchronized cardioversion|
|If patient is in SVT with aberrancy||Adenosine 6 mg rapid IV push If no conversion, give 12 mg rapid IV push; may repeat 12 mg dose once|
|Wide (>0.12) QRS complex|
|Irregular rhythm||Seek expert consultation|
|If pre-excited atrial fibrillation (AF + WPW)||Avoid AV nodal blocking agents such as adenosine, digoxin, diltiazem, verapamil|
|Consider amiodarone 150 mg IV over 10 min|
|If recurrent polymorphic VT||Seek expert consultation|
|If torsades de pointes||Give magnesium (load with 1-2 g over 5-60 min; then infuse|
ou may not always be able to tell from the ECG whether the rhythm is ventricular or supraventricular. Most wide-complex tachycardias originate in the ventricles (particularly if the patient is older or has underlying heart disease). If the patient does not have a pulse, treat the rhythm as ventricular fibrillation and follow the Pulseless Arrest Algorithm.
If the patient is unstable and has a wide-complex tachycardia, assume the rhythm is VT until you can prove otherwise.