Shocking(ly) Not Enough: Electrical Storm and Refractory VT/VF

Author: Calvin Tan, MD

Based on EM-CCM lecture presented by Taylor Douglas, MD

 

Case presentation: 

A 55-year-old woman with past medical history of HTN and IDDM is brought in by EMS with her husband reporting that she “keeps passing out”. The patient is noted to have an episode of upper extremity contractions and fixed gaze lasting about one minute with immediate return to baseline. During this episode, she is maintaining her airway, spontaneously breathing, and has positive blink-to-threat on exam. 

Following the resolution of the episode, the patient is alert and oriented. The patient is moved to the resuscitation room, placed on a monitor, and IV access is established. FS is 360 mg/dL. Triage vitals were: HR 109/min, RR 18/min, BP 164/95 mm Hg, Temp 97.4F, SpO2 97% on RA. The patient is compliant with home medications and has no known drug allergies.

During the initial evaluation, the patient has a second episode of shaking but before midazolam can be administered for presumed seizure, the patient becomes unresponsive and pulseless. The ED team initiates ACLS to treat the following rhythms:

Ventricular fibrillation (VF)

- Defibrillation x 3

- Epinephrine x3, CaCl, NaHCO3
- ROSC after 12 minutes

One minute later, pulseless ventricular tachycardia (VT)
- Defibrillation x 2
- ROSC after 2 minutes
- Lidocaine bolus and infusion
- Epinephrine infusion, magnesium bolus

20 minutes later, VT with pulse
- Shock delivered
- Epinephrine discontinued

An ECG is obtained:

There is posteroinferior ischemia likely due to occlusion MI. The cath lab is activated for emergent PCI.

The patient then develops multiple episodes of malignant ventricular tachydysrhythmia and is treated with electrical therapy. The patient is started on norepinephrine infusion and transferred to the cath lab for PCI. 

Ventricular tachycardia/ventricular fibrillation storm (VT/VF storm):

VT/VF storm is defined as three or more episodes of VF or sustained VT within a 24-hour period. The aberrant rhythms in these patients are often easily aborted with electrical conversion, but will, by definition, recur. Note that VT/VF storm is different from refractory VT in which sinus rhythm is never restored.

It is important to differentiate VF/VT storm from Torsades de Pointes. The best way to do this is to get an ECG when the aberrant tachyarrhythmia stops or is aborted and calculate the QTc. If the QTc is within normal range for the patient, Torsades is effectively ruled out. However, if the etiology is unclear or non-arrhythmic EKG cannot be obtained or is delayed, magnesium should be given empirically to cover for possible Torsades and may also help resolve VT/VF storm through antagonism of calcium. [12]

The cause of VT/VF storm is identified in only about 10% of cases.[1] Possible triggers include acute coronary occlusion, CHF exacerbation, electrolyte imbalance, medication toxicity, medication non-adherence, thyrotoxicosis, and sepsis. The common thread is that these triggers either alter the membrane potential of cardiac myocytes, increase sympathetic tone, or both, which puts the heart in a more excitable state.

The presentation of VT/VF storm can be variable but should be on the differential for any patient with recurrent symptoms of possible cardiac etiology. The range of symptoms and presentations may be as benign as palpitations or as severe as recurrent, unstable rhythms or cardiac arrest (as in the above patient). In a patient with an implanted cardiac defibrillator (ICD), the patient may present for persistent ICD firing.

 

Pathophysiology:
Notwithstanding the triggering event, an episode of VT/VF in and of itself can prime the myocardium for VT/VF storm through a series of physiologic changes and increased sympathetic tone in response to pain and malperfusion.

Repeated, rapid depolarization of the cardiac myocytes leads to increased intracellular calcium which further destabilizes the membrane potential. Electrical shocks delivered in order to defibrillate or cardiovert the heart can lead to injury of the myocardium as can myocardial hypoperfusion caused by the unstable rhythm itself. [1,11]

The combination of an unstable myocyte membrane potential, myocardial injury, and the stress and pain of cardiac resuscitation leads to increased sympathetic tone through catecholamine release which further promotes arrhythmogenicity in an already unstable myocyte membrane and potentiates the cycle. 

 

Management:
Management of a patient with VT/VF storm begins with assessing for a pulse. In the case described above, the patient reportedly had spontaneous respirations even while losing pulses during arrhythmic episodes; ACLS resuscitation should be guided by whether or not pulses are present.

If the patient is pulseless, resuscitation can start with rhythm assessment - shockable (pulseless VT or VF) vs non-shockable (PEA, asystole). If the patient has a pulse, management should begin with trying to identify a cause; however, patients in VT/VF storm may not have a readily identifiable cause. Patients with persistent arrhythmia, like the one described in the case, are at risk of losing airway control and intubation should be considered while trying to identify and correct underlying etiologies. The sedation used following intubation - especially propofol - can be a helpful first step in treating VT/VF storm by decreasing sympathetic tone. [10]

While aggressive sedation may help in controlling the pathophysiologic VT/VF storm cycle (described above) of increasing sympathetic tone, ischemia/malperfusion, and pain; the use of a sedative such as propofol may be limited by its propensity to cause hypotension from vasodilating effects. This can be counteracted directly by use of phenylephrine or use of a different sedative agent such as dexmedetomidine or a benzodiazepine. [11,12]

With airway and breathing controlled, management can move to circulation, more specifically maintaining blood pressure. An arterial line should be strongly considered for accurate real-time blood pressure monitoring. Early initiation of pressor support should be considered in these patients as it can help facilitate use of beta blockers and/or propofol. Additionally, maintaining adequate diastolic blood pressure helps support coronary artery perfusion. Because phenylephrine is a purely alpha-adrenergic agent, it may the best pressor choice in patients with VT/VF storm. Other pressor agents such as epinephrine, norepinephrine, or dopamine have effects on beta-receptors which are pro-arrhythmic. This can lead to increased heart rate and oxygen demand in already ischemic myocardium further promoting arrhythmia. [2,3,4]

As seen in the described case, patients with VT/VF storm are prone to spontaneously returning to  disorganized and/or non-perfusing rhythms. If pulses or organized cardiac rhythm is lost during assessment, resuscitation should begin again per ACLS starting with assessment of pulse status.

Rhythm control

First line: Amiodarone [13]		300 mg bolus 0.5-1 mg/min drip Can repeat bolus (max 1200 mg total)
Second line: Beta blocker [5,6]	Esmolol	0.5 mg/kg bolus 0.05 mg/kg/min drip (max 0.3 mg/kg/min) Requires additional bolus with each drip increase
	Propranolol*	0.15 mg/kg bolus over 10 minutes Repeat 3-5 mg push every 6 hours
Third line: Lidocaine [7]**		1-1.5 mg/kg bolus 0.02 mg/kg/min drip (max 4 mg/min) Can repeat bolus (0.5-0.75 mg/kg, max 3 mg/kg total)

*May be preferred due to activity on both B1 and B2 receptors

**Efficacy may be limited to acute MI-related tachydysrhythmia (automatic, not reentrant)

 

Treatment of cause

Ultimately, termination of VT/VF storm centers on addressing the underlying cause if one can be identified. If the patient’s arrhythmia, as in the above case, is thought to be due to occlusion MI then reperfusion (thrombolysis or PCI) and mechanical circulatory support, if needed, should be initiated while managing VT/VF storm.

In one randomized controlled study, patients with out of hospital cardiac arrests found to be in refractory VF were sorted into two groups - rapid VA-ECMO vs standard ACLS. Survival to hospital discharge between the two groups was 43% to 7%, respectively. 6-month survival in studied patients was 43% vs 0% in favor of patients randomized to VA-ECMO. While these results may help support the role of VA-ECMO in patients with arrest in the setting of VF/VT storm, institution-specific factors may play a large role in recreating these benefits. [8]

If no underlying cause is identified, catheter ablation of VT/VF storm is another option for definitive treatment in both the emergent and long-term settings. Though the mortality benefit of catheter ablation has not been demonstrated in a randomized control trial, multiple studies have shown successful termination of arrhythmias as well as long-term rhythm control compared to escalating anti-arrhythmic drug therapies. [9]

Other causes of VF/VT storm such as electrolyte abnormality, sepsis, or medication toxicity should be managed in order to terminate the aberrant rhythm. Management of the underlying cause should be conducted in conjunction with management of the patient’s arrhythmia. 

Case Conclusion:

Coronary angiography identifies diffuse, 100% stenosis of the RCA with thrombus that is successfully stented with 0% residual stenosis. Ventriculography demonstrates EF of 35% with hypokinesis in multiple areas. Subsequent TTE shows EF of 15% with significant, severe hypokinesis and markedly reduced RV function. 

The decision is made to transfer the patient to an ECMO and cardiac transplant center for further evaluation and possible advanced intervention. During the first inpatient week, the patient has one episode of recurrent VT that resolves with antiarrhythmic therapy. She is eventually weaned off pressors and extubated.

She is ambulatory by hospital day 11 and is discharged on guideline-directed medical therapy, wearable defibrillator, and amiodarone. The amiodarone is discontinued at one-month follow-up, and the defibrillator is discontinued at three months. 

 

Take-home points:

- VT/VF storm is defined as 3 or more episodes of VF or sustained VT within a 24-hour window. Arrhythmias are usually amenable to electrical or pharmacologic termination but continue to recur.
- Identifying and treating the underlying cause is the most effective way to abort the VT/VF storm cycle and prevent arrhythmia recurrence.
- Whether or not an underlying cause is identified, management should follow ACLS guidelines depending on whether or not the patient has a pulse and the specific rhythm.
- Decreasing sympathetic tone through sedation, airway control, pain control, or a combination thereof can help decrease arrhythmogenicity of the myocardium.
- Consider amiodarone, beta-blockers, or Class 1 antiarrhythmics as indicated for pharmacologic rhythm control.
- In patients with VT/VF storm, consider VA-ECMO and catheter ablation in addition to pharmacologic therapies. 

 

References

[1] Muser D, Santangeli P, Liang JJ. Management of ventricular tachycardia storm in patients with structural heart disease. World J Cardiol. 2017;9(6):521-530.

[2] Midei MG, Suguira S, Maughan WL, et al. Preservation of ventricular function by treatment of ventricular fibrillation with phenylephrine. J Am Coll Cardiol. 1990;16(2):489-494.

[3] Richards E, Lopez MJ, Maani CV. Phenylephrine. StatPearls. 2021.

[4] Lankadeva YR, Evans RG, Bellomo R, et al. Chapter 225 - Vasoactive Drugs, Renal Function, and Acute Kidney Injury. Critical Care Nephrology (Third Edition). 2019;1344-1348.e2.

[5] Fita G, Gomar C, Rovira I. Esmolol in anesthesiology: pharmacology and indications. Rev Esp Anestesiol Reanim. 1999;46(9):404-414.

[6] Shahrokhi M, Gupta V. Propranolol. StatPearls. 2021

[7] Geraghty L, Santangeli P, Tedrow UB, et al. Contemporary management of electrical storm. Heart Lung Circ. 2019;28(1):123-133.

[8] Yannopoulos D, Bartos J, Raveendran G, et al. Advanced reperfusion strategies for patients with out-of-hospital cardiac arrest and refractory ventricular fibrillation (ARREST): a phase 2, single centre, open-label, randomised controlled trial. Lancet. 2020;396(10265):1807-1816.

[9] Sapp JL, Wells GA, Parkash R, et al. Ventricular tachycardia ablation versus escalation of antiarrhythmic drugs. N Engl J Med. 2016;375(2):111-121.

[10] Burjorjee J, Milne B. Propofol for electrical storm;  a case report of cardioversion and suppression of ventricular tachycardia by propofol. Can J Anaesth. 2002;49(9):973-977.

[11] Eifling M, Razavi M, Massumi A. The evaluation and management of electrical storm. Tex Heart Inst J. 2011;38(2):111-121.

[12] Farkas J. Non-torsade VT/VF storm. The Internet Book of Critical Care. 2016. Accessed 08/2021. https://emcrit.org/ibcc/storm/

[13] Sorajja D, Munger TM, Shen W. Optimal antiarrhythmic drug therapy for electrical storm. J Biomed Res. 2015;29(1):20-34.