Question 8

A 59-year-old patient with a known history of ischaemic dilated cardiomyopathy (ejection fraction (EF) 25%), with an automatic implantable cardioverter defibrillator (AICD) in situ, has presented to the Emergency Department as the AICD has appropriately delivered 15 shocks in the past 4 hrs. ECG shows sinus rhythm with pre-existing left bundle branch block (LBBB).

The patient is cooperative with a GCS of 15 but distressed by the repetitive shocks.

The airway is maintained. Blood pressure is 90/65 mmHg, heart rate is 105/minute, sinus rhythm. Peripheral oxygen saturations are 96% on room air.
Outline your management of this patient.

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College Answer

Syllabus topic/section:

2.1.4    Cardiovascular Intensive Care – L1.

Aim:
Assess a candidate’s knowledge of AICD and management of VT storm.
Discussion:
Candidates scored marks if they mentioned accurate patient risk stratification and appropriate management according to hemodynamic tolerability e.g. Patient is GCS 15 - organ perfusion maintained- categorized as stable VT.
Higher marks were achieved if the answer Included – ruling out all potentially reversible causes, administering anti-arrhythmic drugs in staged sequence and then considered general anesthesia (to reduce the sympathetic surge) and mechanical hemodynamic support (as EF 25%- Poor LVEF) as a rescue therapy prior to proceeding to Radiofrequency ablation (definitive therapy).

Candidates scored poorly if focus concentrated on a malfunctioning AICD as the stem specified that the shocks delivered were appropriate. Candidates did not score marks for elaborating on assessment when management (resuscitation, definitive treatment, initial and ongoing monitoring with supportive treatment) had been specifically asked.

Suggested strategies for improvement:

•    Read the SAQ carefully (e.g. the AICD was functioning).
•    Provide a tiered strategy for Mx of refractory VT.
•    Use the glossary of terms to understand the direction of the question.
•    Have practiced an approach of thinking both long term as well as short term.
 

Discussion

The "outline your management" part of the question may have confused some of the candidates, who may not have included assessment elements in their answer (such as ruling out reversible causes). Similarly, the question stem has given several data points that help you decide whether the patient is stable or unstable (i.e. we know the patient is conscious and has a perfusing rhythm), which would have made it difficult to identify the need to restate these in the answer as a "risk stratification" statement. 

Still, if this is what they wanted,

  • Risk stratification
    • The patient is hypotensive, but there is no evidence of organ hypoperfusion
    • This suggests definitive management can be delayed until the patient is stabilised in the ICU
      • Alternative would have been to go to cath lab for RF ablation on VA ECMO
  • Assessment for reversible causes
    • Biochemistry, including ABG (to exclude electrolyte derangement and acidosis)
    • ECG (evidence of ischaemia)
    • TTE (regional wall motion abnormalities)
  • Tiered management of VT
    • Antiarrhythmics
      • Amiodarone loading dose (5-7mg/kg) followed by infusion
      • Can add lignocaine infusion as second dier
      • Mexelitine and phenytoin are third and fourth line agents
      • When haemodynamically improved, beta-blockade
    • Supportive management
      • Keep sodium ~145 mmol/L using sodium bicarbonate
      • Keep magnesium 1.5-2.0 mmol/L
      • Sedate/anaesthetise the patient to reduce sympathetic drive
  • Refractory VT with cardiogenic shock
    • While waiting for mechanical circulatory support:
      • Inotropes, acknowledging the risk of worsening the arrhythmia
      • Overdrive pacing using transvenous pacing wires or the AICD itself (at 110-120 bpm)
      • Stellate ganglion block or similar sympatholytic technique
    • Mechanical support (IABP or preferably VA ECMO)
  • Definitive management
    • ​​​​​​​Radiofrequency ablation
    • Revascularisation of ischaemic regions
    • Return to ICU on mechanical cardiovascular support

References

Aronow, Wilbert S. "Treatment of Ventricular Arrhythmias." (2014).

Stevens, S., et al. "When Shocking The Electrical Storm Does Not Work..." Am J Respir Crit Care Med 189 (2014): A6153.

Tung, Roderick, and Kalyanam Shivkumar. "Neuraxial modulation for treatment of VT storm." Journal of biomedical research 29.1 (2015): 56.

Scheinman, Melvin M., et al. "Dose-ranging study of intravenous amiodarone in patients with life-threatening ventricular tachyarrhythmias." Circulation 92.11 (1995): 3264-3272.

Kowey, Peter R. "An overview of antiarrhythmic drug management of electrical storm." The Canadian journal of cardiology 12 (1996): 3B-8B.

Gorenek, Bulent, et al. "Cardiac arrhythmias in acute coronary syndromes: position paper from the joint EHRA, ACCA, and EAPCI task force." Europace (2014): euu208.

Kurisu, Satoshi, et al. "Temporary overdriving pacing as an adjunct to antiarrhythmic drug therapy for electrical storm in acute myocardial infarction." Circulation Journal 69.5 (2005): 613-616.

Patel, Rishin A., et al. "Left Stellate Ganglion Blockade for the Management of Drug‐Resistant Electrical Storm." Pain medicine 12.8 (2011): 1196-1198.

Nademanee, Koonlawee, et al. "Treating Electrical Storm Sympathetic Blockade Versus Advanced Cardiac Life Support–Guided Therapy." Circulation 102.7 (2000): 742-747.

BELLA, PAOLO DELLA, and Stefania Riva. "Hybrid therapies for ventricular arrhythmias." Pacing and clinical electrophysiology 29.s2 (2006): S40-S47.