#473 Rapid Response Series: Narrow Complex Tachyarrhythmias with Dr. Noble Maleque

March 3, 2025 | By Meredith Trubitt

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Video

Transcript available via YouTube

Don’t miss a beat as our guest Dr. Noble Maleque guides us through dominating narrow complex tachyarrhythmias (while keeping our own heart rates under control too). @Nobility75 (Emory University)

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Show Segments

• Intro
• Case 1, part 1: Unstable narrow tachyarrhythmias
• Case 1, part 2: Stable, narrow tachyarrhythmias – regular rhythm
• Vagal tone: Valsalva, Modified Valsalva, or Carotid Massage?
• Adenosine
• 2nd line AV nodal blockade: metoprolol, diltiazem
• Case 2: Stable, narrow tachyarrhythmias – irregular rhythm
• AV nodal blockade
• Amiodarone and diltiazem
• Rapid fire questions/Picks of the Week
• Outro

Narrow Complex Tachyarrhythmia Pearls

1. Follow the AHA guidelines for managing tachyarrhythmias.
2. When responding to a page or rapid response for a tachyarrhythmia, ask for a full set of vital signs and patient symptoms over the phone. Ensure there is adequate IV access and either an EKG or rhythm strip for you to analyze as well.
3. Once you arrive in the room, triage whether the patient is stable or unstable using vital signs and symptoms of end-organ dysfunction.
4. For unstable narrow-complex tachyarrhythmias, proceed directly to synchronized cardioversion.
5. For stable narrow-complex tachyarrhythmias, examine the rhythm: regular rhythm includes sinus tachycardia and SVT, and irregular rhythm includes atrial fibrillation and atrial flutter. In all cases, identify and treat underlying precipitants like hypovolemia or infection. 
6. If the arrhythmia persists, attempt a modified Valsalva, followed by intravenous adenosine if there are no contraindications, as these maneuvers can be both diagnostic and therapeutic.
7. If the arrhythmia persists and the patient remains stable, trial other AV nodal blocking agents like metoprolol or diltiazem. If the patient has HFrEF, avoid these agents and consider amiodarone.

Rapid Response Series: Narrow Complex Tachyarrhythmias – Show Notes

Initial Triage

When responding to a page or rapid response for a tachyarrhythmia, ask a few key questions to set you up for success when you arrive in the room. The first box of AHA tachycardia algorithm outlines these questions and suggests initial actions: 

1. “What are the other vital signs?” If the patient is hypotensive, connect them to defibrillator pads, and if they are hypoxemic, provide supplemental oxygen.
2. “Can we connect the patient to the cardiac monitor?” We can use EKG leads if the patient is stable, or defibrillator pads if they are unstable. Telemetry can be a helpful monitoring tool as well, but a cardiac monitor can provide actions like printing a rhythm strip, checking a blood pressure, continue monitoring during transport, cardioversion if indicated, and defibrillation if they become unstable.
3. “What is their IV access?” If you anticipate using adenosine, proximal peripheral access is needed (at the antecubital fossa or higher).
4. “Can we get a 12-lead EKG or rhythm strip?”

Determining Stability

Determining whether the patient is stable or unstable is the first decision to make to identify the appropriate algorithm to use. 

Unstable patients have hypotension or end-organ dysfunction from their tachyarrhythmia. Examples of end-organ dysfunction include altered mental status, chest pain, or acute heart failure. Per the AHA tachycardia algorithm, these patients need urgent synchronized cardioversion, and may require ICU or step-down care, so call cardiology. 

Stable patients may have symptoms (e.g. palpitations) but do not have evidence of end-organ dysfunction. These patients afford you more time to determine the type of tachyarrhythmia, identify and manage any underlying causes, and administer appropriate antiarrhythmics if necessary.

Dr. Maleque also acknowledges that it’s normal to feel nervous in high-acuity situations like this. He encourages thinking out loud and getting input from nursing staff on a patient’s baseline and recent symptoms. He also reiterates that everyone in the room must feel comfortable with the patient’s level of care and to consider escalation of care if indicated.

Differentiating Narrow vs Wide Complexes

Once you have determined whether the patient is stable or unstable, the next branch point in the AHA tachycardia algorithm is determining whether the tachyarrhythmia is narrow or wide complex. Rhythms are wide complex if they are equal to or longer than 0.12 seconds, or 120 milliseconds. This equates to three small boxes on a printed EKG. 

Wide complex tachyarrhythmias should be considered ventricular tachycardia until proven otherwise. These should prompt cardiology consultation and are outside of the scope of today’s episode.

Approach to Identifying Narrow Complex Tachyarrhythmias 

Once you’ve determined that your patient has a narrow complex tachyarrhythmia, the next step is to identify the general type of arrhythmia. Dr. Maleque suggests placing the arrhythmia into one of a few buckets instead of spending valuable time identifying the exact subtype. His expert opinion is that precise identification isn’t essential for bedside management with some rare exceptions (e.g. identifying pre-excitation conditions like Wolff-Parkinson-White, in which case nodal blockers may worsen tachycardia). Plus, even experts have a difficult time determining the rhythm when it is very fast.

The major buckets that Dr. Maleque identifies are: 

1. Regular rhythm: sinus tachycardia
2. Regular rhythm: supraventricular tachycardia (aka SVT, which includes AVRT and AVNRT)
3. Irregular rhythm: atrial fibrillation (aka Afib) or atrial flutter with rapid ventricular response (aka RVR)

Determining whether the rhythm is regular or irregular can be challenging when the rate is fast, as the p waves and t waves can overlap. Several clues can help you make this determination: 

1. EKG: gold standard, but rhythm identification can be difficult. For review of specific diagnostic ECGs, you can use the library from Life in the Fast Lane.
2. Clinical history or trigger: was their inciting event (e.g. pain, infection, hypovolemia) that may have triggered a tachyarrhythmia such as sinus tachycardia or atrial fibrillation with rapid ventricular rate, or was there no clear trigger as may sometimes be the case with SVT?
3. Onset and/or termination (e.g. slowly ramped up like sinus tachycardia vs immediate start like Afib or SVT)
4. Response to Valsalva maneuver and/or adenosine: the valsalva maneuver and adenosine (both discussed in more detail below) can be diagnostically useful as they can slow down non-reentrant rhythms like sinus tachycardia and Afib or flutter, and may terminate SVT altogether. 

Approach to Managing Narrow Complex Tachyarrhythmias 

First and foremost, identify and treat any potential arrhythmia trigger(s) like infection and hypo- or hypervolemia. For sinus tachycardia, this is your only management option. For other narrow complex tachyarrhythmias such as SVT or Afib with RVR, physical exam maneuvers and/or antiarrhythmic drugs are needed.

Vagal Maneuvers

There are many vagal maneuvers at your disposal, including the Valsalva maneuver, the modified Valsalva, carotid sinus massage, and water immersion, especially cold water immersion of the face (to elicit the “diving reflex”). 

In a randomized control trial of patients presenting to the emergency department with SVT, the modified Valsalva maneuver was more efficacious for restoring sinus rhythm compared to a standard valsalva (43% vs 17% success rate) (Appelboam, 2015). An older, smaller study also compared the efficacy of the Vаlsalva maneuver, right carotid sinus massage, left carotid massage, and eliciting the diving reflex. That study found that the supine Valsаlvа maneuver was the most successful for terminating SVT (54%), followed by the diving reflex (17%), and performing carotid sinus massage on the right (17%) and left (5%) sides (Mehta, 1988).

Antiarrhythmics

The first-line pharmacologic option is adenosine as it can be both diagnostic and therapeutic. Adenosine effectively terminates >80% of cases of SVT, but there are important contraindications to use and adverse effects. Contraindications include reactive airway disease (e.g. COPD) or severe coronary artery disease. Side effects are often uncomfortable for patients and include flushing, palpitations, and the feeling of impending doom. Adenosine can also cause clinician discomfort, as it causes transient asystole, requiring continuous EKG monitoring during administration. Adenosine has a very short half-life (<5 seconds) and thus must be administered at or above the antecubital fossa, via a 3-way stopcock with saline immediately flushing it. Doses escalate from 6mg → 12mg → 12mg if the desired effect is not achieved. 

Second-line AV nodal blocking agents for SVT and first-line rate control agents for Afib with RVR include metoprolol and diltiazem. Diltiazem is dosed 0.25 mg/kg IV for the first dose, and 0.35 mg/kg after 15 minutes for the second dose, if necessary. Dr. Maleque observes that lower doses of diltiazem are often used (e.g. 10 mg) due to fear of hypotension. Metoprolol is dosed 5 mg IV every 5-10 minutes as needed for up to 3 doses. Both of these drugs are negative inotropes, so caution is warranted in patients with acute decompensated heart failure and an unknown ejection fraction. Amiodarone is often a safer choice for such patients. Amiodarone is dosed 150 mg IV over 10 minutes to lower the risk of hypotension, followed by a 1 mg/min infusion. Digoxin is also an option, but this is rarely used in a rapid response situation unless there is a contraindication to amiodarone due to its slower onset of action.

Anticoagulation decisions should be made based on the patient’s CHA₂DS₂-VASc score. 

Links

1. Ninja SLUSHi™ Professional Frozen Drink Maker
2. Snow Leopards at the Woodland Park Zoo in Seattle 

Goal

Listeners will develop a framework to approach the triage, evaluation, and management of narrow complex tachyarrhythmias.

Learning objectives

After listening to this episode listeners will…  

1. Develop an approach for triaging common tachyarrhythmias encountered in the inpatient setting.
2. Learn a tachyarrhythmia algorithm organized by stability of the patient and width of the QRS complex.
3. List diagnostic maneuvers and management pearls for narrow complex, stable tachyarrhythmias.

Disclosures

Dr. Maleque reports no relevant financial disclosures. The Curbsiders report no relevant financial disclosures. 

Citation

Maleque N, Coleman CG, Trubitt ME, Amin M, Williams PN, Watto MF. “#473 Rapid Response Series: Narrow Complex Tachyarrhythmias with Dr. Noble Maleque”. The Curbsiders Internal Medicine Podcast. thecurbsiders.com/category/curbsiders-podcast March 3rd 2025.