Tachyarrhythmias and tachycardia both refer to heart rhythms that are over 100 beats per minute. While tachycardia usually refers specifically to sinus rhythms over 100 beats per minute, the two terms are often used interchangeably. Consequently, we use tachycardia to refer to all rhythms (sinus or non-sinus) that are > 100 beats per minute. 

The algorithm for tachycardia with a pulse is used to manage patients who present with tachycardia. Like bradycardias, it is useful to evaluate three factors:

• The patient has a tachycardia
• The patient has symptoms or signs caused by tachycardia
• The patient can be stable or unstable

Algorithm: Short Description

This algorithm outlines the steps to guide the provider to efficiently assess and manage a patient with tachycardia with a pulse.

Algorithm at a Glance

• The provider identifies tachycardia and assesses the patient to determine if the heart rate is appropriate for the patient’s condition.
• If possible, the provider identifies and treats the cause of the tachycardia.
• Vagal maneuvers may be attempted if the patient’s condition allows it.
• If the patient is symptomatic, the provider considers administering sedation followed by synchronized cardioversion.

Goals for the Management of Adult Tachycardia

The provider must succeed in the following goals to successfully manage patients with tachycardia: 

• Identify the tachycardic rhythms, including:
  • Sinus tachycardia
  • Atrial fibrillation
  • Atrial flutter
  • Supraventricular tachycardia (SVT)
  • Wide complex tachycardia
• Identify symptomatic tachycardia with a pulse
• Appropriately treat the patient with symptomatic tachycardia with a pulse.

The Adult Tachycardia Algorithm

This algorithm was created to outline the steps for assessing and managing patients presenting with symptoms of tachycardia.

Adult Tachycardia With a Pulse Algorithm

Related Video: Understanding the ACLS Tachycardia with a Pulse Algorithm

Box 1: Assessing Appropriateness of Heart Rate for Patient’s Condition

A fast heart rate may be due to a physiologic response to stress, such as dehydration or fever. Significant tachyarrhythmia, however, is a heart rate > 150 beats/minute. Clinicians agree that when the heart rate is < 150 beats/minute, patients are unlikely to experience symptoms and instability unless there is preexisting impaired ventricular function. 

When diagnosing a patient, the clinician must distinguish whether the tachyarrhythmia is a primary cause of the patient’s symptoms or a result of physiologic stress from other disease conditions. 

Box 2: Identifying and Treating the Underlying Cause 

Hypoxemia can cause tachycardia, which is quite common. The team treats symptomatic patients based on the signs and symptoms of increased breathing effort (e.g., tachypnea and intercostal retractions). Oxygen saturation should be determined immediately using a pulse oximeter and oxygen administered to the hypoxemic patient. 

The patient should be monitored carefully using a cardiac monitor and with intermittent blood pressure readings. A 12-lead ECG can better evaluate the tachyarrhythmia diagnosis, but cardioversion should not be delayed if it is indicated. 

At this stage, the provider looks at the possible causes of tachyarrhythmia and treats it promptly. A decision to seek expert help may be made at any time during the management of a tachycardic patient.

Box 3: Tachycardia with Persistent Symptoms

After initial evaluation and treatment with airway and oxygen supplementation, the patient may have ongoing symptoms. The provider determines that the symptoms are due to the tachyarrhythmia and diagnoses it as the primary cause. 

Unstable symptoms are secondary to reduced cardiac output, as the heart beats too fast or ineffectively due to a lack of coordination between the atria and ventricles. Especially when persistent, this arrhythmia can cause hypotensive symptoms, altered mental status, ischemic chest discomfort, acute heart failure, and signs of shock. 

If the patient is hemodynamically stable, the team proceeds to Box 4. If hemodynamically unstable, they proceed to Box 5.

Box 4: Synchronized Cardioversion

Before administering synchronized cardioversion to a patient with unstable tachyarrhythmia, the team attempts to establish IV or IO access for possible sedation. Although sedation is preferable for the conscious patient, cardioversion should not be delayed if the patient is unstable, as cardiac arrest may ensue.

Synchronized cardioversion is a method of delivering a shock that is in sync with the QRS complex (delivered at the peak of the R wave). A shock during the relative refractory period of the cardiac cycle in tachyarrhythmias can produce VF, thus worsening the condition of the patient.¹⁶

Related Video: Synchronized Cardioversion for Tachycardia

If the tachyarrhythmias have polymorphic QRS complexes (i.e., torsades de pointes) in the ECG tracing, synchronization cannot occur. Thus, attempting synchronized cardioversion would be ineffective, and the team should treat torsades de pointes like VF with unsynchronized defibrillation. 

Some patients with a regular, narrow complex tachycardia may respond to adenosine administration rather than cardioversion. 

No data are available to recommend one type of biphasic defibrillator over another. Responders should follow the manufacturer’s instructions to choose the dose of energy for the initial shock. If there are no instructions, the maximal energy dose available should be used.

Box 5: Is the QRS Complex Regular or Wide?

Wide-Complex Tachycardia

If the patient is stable and does not require immediate cardioversion, it must be determined whether the QRS is normal or wide (> 0.12 seconds). 

An unstable patient diagnosed with wide complex tachycardia should be presumed to have VT, and the appropriate treatment is cardioversion. The team proceeds to Box 6. 

If a defibrillator is not immediately available in a case of witnessed, monitored unstable ventricular tachycardia, the provider can attempt a precordial thump unless doing so would delay definitive treatment.

If the QRS is < 0.12 seconds wide, the team proceeds to Box 7.

VT is a common form of wide-complex tachycardia. SVT with aberrancy, pre-excited tachycardias, and ventricular paced rhythms are also wide-complex tachycardias that can either be VT or SVT with aberrancy. The only difference is that SVT with aberrancy is, as the name suggests, supraventricular. 

To distinguish between the two, the team can treat SVT with aberrancy with AV-nodal blocking agents. However, patients with VT may suffer precipitous hemodynamic deterioration if erroneously administered an AV-nodal blocking agent. An electrocardiographic differentiation between the two is not always possible. It is critical to seek expert consultation when there is difficulty in determining the patient’s rhythm.

The team must determine if the wide-complex tachycardia has a regular or irregular rhythm. If it has a regular rhythm, then it is likely due to VT or SVT with aberrancy. An irregular rhythm is due to atrial fibrillation with aberrancy, pre-excited atrial fibrillation, or torsades de pointes. Providers may need to seek expert help in diagnosing wide-complex tachycardia. 

Box 6: Therapy for Wide-Complex Tachycardia

It is ideal first to identify if the wide-complex tachycardia is due to VT or SVT with aberrancy and determine the proper treatment as suggested in the algorithm. If the team is unable to distinguish between the two, it is reasonable to treat the patient with IV adenosine to provide a diagnostic benefit as long as the patient is stable. 

Continuous ECG monitoring is necessary. If the rhythm changes to sinus after adenosine, then the wide-complex tachycardia was due to SVT with aberrancy. If the rhythm does not improve, then adenosine has not affected the rhythm (with the exception of idiopathic VT, which is rare). 

Adenosine 6 mg is administered as a rapid IV push followed by a 20 mL normal saline flush. If the rhythm fails to convert, then it can be followed with 12 mg of adenosine. A defibrillator is always on standby when giving this treatment. At this point, the team leader considers an antiarrhythmic infusion and expert consultation.

Related Video: Adenosine – ACLS Drugs

If the patient is unstable, adenosine might cause the rhythm to revert to VF, which is more detrimental, causing hemodynamic failure. Hence, unstable wide-complex tachycardia is a contraindication for adenosine. Verapamil should not be used for wide-complex tachycardia unless it is supraventricular in origin.

It is appropriate to give IV antiarrhythmics such as procainamide, amiodarone, or sotalol for wide-complex tachycardias. However, for patients with prolonged QT interval, procainamide and sotalol should be avoided. 

Whenever antiarrhythmic therapy fails, it is appropriate to try cardioversion, and the provider should consider expert consultation.

Box 7: Narrow Complex Tachycardia

For a narrow-complex tachycardia, the team obtains IV or IO access and a 12-lead ECG. It is reasonable to attempt vagal maneuvers and adenosine. The provider may order β-blockers or calcium channel blockers and calls for an expert consultation.

Box 8: Persistent Tachycardia

In the presence of refractory tachycardia, the provider determines the underlying cause and considers adding antiarrhythmic medications.

Following this initial evaluation, determining the types of tachycardia and treating the patient according to their underlying causes will be important.

Related Video: Understanding the ACLS Tachycardia with a Pulse Algorithm