CONTENTS
- Background
- TREATMENT
- Related topics
- Podcast
- Questions & discussion
- Pitfalls
what is VT/VF storm (a.k.a. “electrical storm”)?
- Definition
- Generally defined as three or more episodes of VF or sustained VT requiring intervention (e.g., defibrillation or ICD shocks) within 24 hours.
- Patients can be shocked out of VT/VF reasonably easily, but then they keep flipping back into to VT/VF (this differentiates VT storm from refractory VT, wherein the patient is continually in VT/VF and never goes back to sinus rhythm).
- If a patient is shocked out of VT/VF and then has a recurrence very soon thereafter, this may be a harbinger of VT/VF storm (and might be considered storm by some).
- Presentation typically dramatic:
- (a) If patient has an ICD (implanted cardiac defibrillator), this may present with recurrent ICD firing.
- (b) If patient doesn't have an ICD, this may cause recurrent symptoms. Depending on the heart rate and cardiac function, symptoms may range from palpitations to recurrent cardiac arrest.
- The problem with VT storm isn't generally breaking any individual episode of VT. Rather, the problem is often that the VT keeps on coming back – so it's difficult to keep patients out of VT for a prolonged period of time.
this chapter is about monomorphic VT, or polymorphic VT due to ischemia
- Polymorphic VT has a complex differential diagnosis as shown in the figure below.(31352528)
- Most polymorphic VT is due to acquired torsade de pointes. This requires specific management as described in the torsade chapter.📖
- Some polymorphic VT is due to acute ischemia. If this causes electrical storm, it should be treated similarly to monomorphic VT (as described in this chapter).
- Occasionally, polymorphic VT may be caused rare, congenital entities (e.g., Brugada Syndrome) that require unique management.
- This chapter discusses a treatment approach to monomorphic VT, or polymorphic VT due to ischemia. The treatment of these entities is very similar, although there may be a greater urgency to persue revascularization in the context of polymorphic VT due to acute ischemia.
VT storm is a vicious cycle
- VT/VF increases intracellular calcium levels, which may be pro-arrhythmic.
- Shocks and episodes of cardiac arrest (e.g. treated with epinephrine) may cause myocardial injury.
- Myocardial injury and pain stimulate an outpouring of endogenous catecholamines, promoting recurrent arrhythmia.
- Key point: The natural history of VT storm is generally to deteriorate (even despite the use of standard ACLS algorithms to interrupt each individual episode of VT). Aggressive therapy is needed to stop this process.
underlying substrate
- Most patients have severe structural heart disease (usually ischemic cardiomyopathy).
- If the patient has a structurally normal heart, this suggests a rare form of arrhythmia requiring specific management (e.g., Brugada syndrome, catecholaminergic polymorphic VT).
🔑 Call for help early and try to think a couple steps ahead (e.g., order IV propranolol early).
magnesium & electrolyte repletion
- 2-4 grams of IV magnesium sulfate may be considered, particularly if the patient is deficient.
- There is no strong evidence to support the use of magnesium. Given that intracellular calcium overload may be implicated in VT/VF storm, magnesium might be expected to alleviate this problem, given that magnesium may antagonize some of calcium's effects.
- Hypokalemia should be aggressively corrected.
1st line antiarrhythmic: amiodarone
- Backbone regimen: 300 mg bolus, then 1 mg/min x6 hours, then 0.5 mg/min.
- Additional boluses can be given for recurrence (up to a total of ~900 mg in boluses).
- Avoid >2.2 grams total dose within 24 hours (i.e., >900 mg in bolus doses).
- If the patient is on chronic oral amiodarone, they should still be reloaded with IV amiodarone.(34257075)
2nd line antiarrhythmic: beta-blockers (may actually be the most effective therapy)
propranolol 💊
- Propranolol is probably superior to metoprolol and esmolol because it antagonizes both beta-1 and beta-2 receptors. Patients often have chronic heart failure, which may lead to down-regulation of beta-1 receptors and up-regulation of beta-2 receptors.(36837606)
- IV regimen: (10942741, 25745472, 32345562)
- Loading bolus 0.15 mg/kg IV over 10 minutes (~10 mg). Follow heart rate and hold the infusion if the heart rate falls <45 b/m.
- Maintenance: 3-5 mg IV Q6hr.
- Oral regimen:
esmolol infusion 💊
- Loading dose is 0.5 mg/kg IV (~30 mg) over one minute.
- Start infusion at 0.050 mg/kg/min (~3 mg/min).
- May re-load & up-titrate infusion in increments of 0.05 mg/kg/min every 10 minutes, up to a maximal dose of 0.3 mg/kg/min (~20 mg/min).
- The advantage of esmolol is titratability. From a mechanistic standpoint, esmolol may be less effective than propranolol because it lacks efficacy at beta-2 receptors.(25033747, 10942741)
IV metoprolol 💊
- May be used if nothing else is readily available.
- Dose: 5 mg IV every 5 minutes for total of 15 mg.
3rd line antiarrhythmic: lidocaine 💊
utility
- Lidocaine is traditionally recommended as the third-line antiarrhythmic, after amiodarone and beta-blockers.
- Lidocaine is only modestly effective in scar-related monomorphic VT, but it may be more useful in the context of acute ischemia.(28706587; 31352528)
- Lidocaine is relatively hemodynamically stable, but class-I antiarrhythmics can worsen cardiac function due to negative inotropic effects – so exercise some caution.(30554598)
dose
- Bolus with 1-1.5 mg/kg and then infuse at a rate of 0.02 mg/kg/min (~1.5 mg/min).(28706587)
- May re-bolus with 0.5-0.75 mg/kg IV, up to a total dose of 3 mg/kg.
- May titrate the lidocaine infusion up to ~4 mg/min.
intubation
- This is generally required for a true VT storm. Intubation offers numerous benefits:
- Patients may lose airway control during episodes of VT/VF.
- Sedation itself is therapeutic.
- Intubation may facilitate safe performance of procedures (e.g., VT ablation).
analgesia
- Analgesia is important for any intubated patient, but it's especially important in VT storm because untreated pain can drive sympathetic tone and promote recurrent arrhythmia.
- Initially err on the side of over-aggressive analgesia (until the VT storm is controlled).
sedation
- Deep sedation can help break the VT storm.
- Propofol seems to work particularly well here.(12419728)
- Propofol may cause hypotension due to vasodilation; this may be counteracted with the use of vasoconstrictors (e.g., phenylephrine).
- Dexmedetomidine may also reduce sympathetic tone, so it's not a terrible choice here. However, dexmedetomidine has some drawbacks which probably make it 2nd line here (at least initially until the storm has abated):
- Dexmedetomidine is sluggish to titrate.
- Dexmedetomidine can't achieve the same depth of deep sedation that propofol can.
- To date, there is no evidence on using dexmedetomidine in VT storm.
- Benzodiazepine may be used if the patient is unable to tolerate propofol/dexmedetomidine due to severe hypotension.
arterial line
- These patients are often very hemodynamically labile (e.g., with recurrent episodes of cardiac arrest). Additionally, we will usually be aggressively titrating medications that cause hypotension (e.g., propofol, amiodarone, beta-blockers).
- An arterial line is often helpful.
pressors
- Phenylephrine may be the best choice, because it won't stimulate cardiac beta-receptors.
- Pressor support may facilitate the use of propofol and beta-blockers to treat VT storm.
- The left ventricle coronary circulation is perfused in diastole, so don't allow the diastolic Bp to decrease too much.
reverse any identifiable triggers, e.g.:
- Acute MI.
- Recurrent VT/VF should always prompt consideration for emergent cardiac catheterization.
- Additional therapies for acute coronary syndrome should also be considered (e.g., aspirin, P2Y12 inhibitor). More on the treatment of Type I MI: 📖
- Electrolyte abnormalities, especially:
- Hypokalemia.
- Hypomagnesemia.
- Medications:
- Pro-arrhythmic drug toxicity.
- Medication non-adherence.
- Substance abuse (e.g., sympathomimetics).
- Thyrotoxicosis.
- Sepsis. (30554598)
- Volume overload.
- Severe anemia.
ICD (implanted cardioverter-defibrillator) optimization
- Any patient with an ICD requires device interrogation.
- Ensure that the device is truly detecting VT (rather than over-responding to artifact). Additionally this may help clarify whether the patient has monomorphic or polymorphic VT.
- Anti-tachycardia overdrive pacing may be optimized to break episodes of VT without requiring shocks.
catheter ablation of VT/VF
- Recent meta-analysis of 417 patients with VT storm demonstrated clinical arrhythmia suppression in 92% of patients, with an impressive safety profile (complication rate of 1% and periprocedural mortality of <1%).(23264584)
- Urgent ablation is recommended by numerous society guidelines for the management of refractory VT.(34257075)
- Patients who have had a VT/VF arrest causing anoxic brain injury require temperature management to prevent neurologic injury. 📖
basics of the stellate ganglion block
- Nerve block in the neck cuts off sympathetic outflow to the myocardium.
- Supported by case-study level data, which show a dramatic reduction in arrhythmia burden.(30554598)
- Seems fairly safe (e.g. used as an outpatient procedure for control of neuropathic pain).
- Sensible intervention for patients failing to respond to intubation & anti-arrhythmics.
- The block should cause an ipsilateral Horner's syndrome (pupillary constriction), which is evidence of a successful block.
left stellate ganglion block versus bilateral blocks?
- The left stellate ganglion is more important in autonomic regulation of the heart, so most literature has described unilateral left-sided blockade.
- In a recent systematic review of the literature, 34/38 reported cases received left-sided block, with the remaining four receiving bilateral blocks.(29270467)
- However, bilateral blockade may be most effective. Some authors are currently advocating for bilateral blockade.(28471068)
basic anatomic principles
- (1) Operate at the level of the C6 transverse process (Chassaignac's tubercle; figure above).
- This bony structure might be appreciated with deep palpation adjacent to the trachea at the level of the cricoid membrane.
- The C6 transverse process should be visible during the procedure as a bright, bony signal.
- The C6 transverse process provides a back-stop which blocks the needle from hitting the vertebral artery (although ideally you should never hit the bone).
- (2) The injection target is just anterior to the longus coli muscle, which runs underneath carotid artery.
overview of two different techniques
Two general techniques may be used. There's no firm evidence regarding which is better, so both will be described here.
“landmark technique” approach
- Traditionally, stellate ganglion blocks were performed using a landmark technique as follows:
- Palpate the neck adjacent to the trachea to locate the lateral process of C6 (Chassaignac's tubercle)
- Insert a needle straight into the neck until it hits Chassaignac's tubercle.
- Inject some local anesthetic, then withdraw 1-2 mm and inject some more anesthetic.
- This is a fast and simple technique (see video below). The problem is that if you're off a little (either too cephalad or caudad) the needle could slip past Chassaignac's tubercle and hit the vertebral artery.
- This approach can be replicated using ultrasonography, which allows needle visualization and prevents going too deep. Ideally anesthetic should be placed just anterior to the longus coli muscle.
lateral approach
- In this approach, the patient's head is turned to the contralateral side. The longus coli is approached lateral to the carotid artery (figure below). As with any technique, the goal is to deposit anesthetic just anterior to the longus coli muscle.
- This technique has the advantage of providing a greater margin of safety between the needle and vital structures (e.g. the carotid artery and thyroid).
A more detailed illustration of the sono-anatomy at the level of C6 is shown below:(24760493)
- The key sono-landmarks are the carotid artery and the Chassaignac's tubercle (marked “at” in the figure below).
- The longus coli (with the ganglion anterior to it) are sandwiched between the carotid artery and the anterior tubercle.
- Using some gentle posterio-medial pressure with the ultrasound probe may displace the carotid artery medially, opening up this space between the carotid and Chassaignac's tubercle.(28455598)
The following video illustrates this general approach, albeit at the C7 level (not my preferred level because, as you can see in the video, incorrect angulation of the needle could risk laceration of the vertebral artery)
Another short video to reinforce the anatomic structures:
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- Unawareness of the entity of VT storm and its specific treatment pathway.
- Failing to differentiate between torsade de Ppointes (TdP) versus non-torsade electrical storm This distinction is critical, because a torsade storm requires entirely different management.📖
- A wait-and-see approach, which will often fail these patients (VT storm is a vicious cycle which often deteriorates without aggressive management). Once a patient has had two-three episodes of VT within a day, strongly consider progressing down the VT storm pathway (with intubation and sedation).
- Under-utilization of sedation, analgesia, and beta-blockers.
Guide to emoji hyperlinks
- = Link to online calculator.
- = Link to Medscape monograph about a drug.
- = Link to IBCC section about a drug.
- = Link to IBCC section covering that topic.
- = Link to FOAMed site with related information.
- 📄 = Link to open-access journal article.
- = Link to supplemental media.
References
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- 12419728 Burjorjee JE, Milne B. Propofol for electrical storm; a case report of cardioversion and suppression of ventricular tachycardia by propofol. Can J Anaesth. 2002 Nov;49(9):973-7. doi: 10.1007/BF03016886 [PubMed]
- 24760493 Narouze S. Ultrasound-guided stellate ganglion block: safety and efficacy. Curr Pain Headache Rep. 2014 Jun;18(6):424. doi: 10.1007/s11916-014-0424-5 [PubMed]
- 25033747 Driver BE, Debaty G, Plummer DW, Smith SW. Use of esmolol after failure of standard cardiopulmonary resuscitation to treat patients with refractory ventricular fibrillation. Resuscitation. 2014 Oct;85(10):1337-41. doi: 10.1016/j.resuscitation.2014.06.032. Epub 2014 Jul 14. PMID: 25033747 [PubMed]
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- 28455598 Kim H, Song SO, Jung G. A lateral paracarotid approach for ultrasound-guided stellate ganglion block with a linear probe. J Anesth. 2017 Jun;31(3):458-462. doi: 10.1007/s00540-017-2354-y [PubMed]
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