ECG in patients with ICD shock

Mid Term ISECON, Thane, Nov 2017

Satish Toal

Director Cardiac Electrophysiology, New Brunswick Heart Centre,

Asst Prof., Dept of Medicine, Dalhousie University

Disclosures

• None

Objectives

• Understand the value of ECG in diagnosing the reason for ICD shock

• Using ECG to formulate a treatment strategy to treat and prevent shocks

• Effect of shocks on ECG

Our aim is to have ICDs that do not shock and pacemakers(except BiV) that do not pace

ICD does not prevent VT, Shocks are not benign and Could be inappropriate

• Why does the ICD shock?

• True Shocks: • ICD determines pt is in VT/VF which needs a shock – some parameters are

programmable by the physician

• Shocks may be • appropriate – for VT/VF or

• inappropriate – “external noise”, SVT, Device and lead issues

• Phantom Shocks: • Pt “perceives” shock, none delivered

• When the pt presents to you in ER • He may have ongoing shocks or

• He may have had a shock or multiple shocks and is seeking medical help

• In both cases ECG is essential and helpful

ECG with h/o ICD shocks, no ongoing shock

• Ongoing arrhythmia • Is it SVT or VT?

• Why is the device not treating it?

• No arrhythmia • Normal ECG - does not rule out appropriate or inappropriate therapy

• Ischemic changes

• Post shock changes

• Changes due to electrolytes

ECG with ongoing shock

• Ongoing arrhythmia • SVT

• VT

• No arrhythmia • Inappropriate shock, likely device or lead issues

• Could also be electrolyte issues

Holmes: “To the curious incident of the dog in the night-time.” Gregory: “The dog did nothing in the night-time.” Holmes: “That was the curious incident.”

Pt receiving shock while on monitor, appropriate or inappropriate?

www.ems12lead.com/2009/05/04/ineffective-or-inappropriate-icd-shocks-part-i

Is this a shock?

H/o recent shock, no ongoing shock

• 60 year old male,

• ICD for primary prevention isch CMP,

• no h/o arrhythmias in past,

• comes with shock in morning while on treadmill,

• stressed but otherwise feels normal

Multiple shocks, but none in ER

• 67 yrs male

• BiV ICD for primary prevention 6 yrs ago

• Good parameters and nice response to Bi V pacing with improvement in EF from 28% to 46%

• Last ICD check 3 months ago normal

• Feeling well but comes with multiple shocks

Ongoing shock in ER

• 71 yrs female,

• BiV ICD for primary prevention 5 days ago,

• presents with ongoing shocks,

• Pt stressed but no h/o chest pain, SOB, dizziness

• telemetry strip preceding shock

Pt with ongoing shock

39 yrs, ICD for secondary prevention, on K supplements, Previous app. Shock, few days h/o vomiting loose motions and now comes with shocks

H/O shock

• A 75-year-old man was admitted to the hospital for multiple implantable cardioverter-defibrillator (ICD) shocks.

• The patient had a history of an inferior myocardial infarction (IMI) secondary to a proximal right coronary artery occlusion.

• His ejection fraction was 40%.

• He had recurrent ventricular tachycardia (VT) for 5 years and had an ICD placed in 2001.

http://dx.doi.org/10.1016/j.hrthm.2015.09.032 Josephson and Wellens Josephson and Wellens ECG Lessons

Presentation ECG

Josephson and Wellens Josephson and Wellens ECG Lessons http://dx.doi.org/10.1016/j.hrthm.2015.09.032

Sinus Rhythm ECG

Josephson and Wellens Josephson and Wellens ECG Lessons http://dx.doi.org/10.1016/j.hrthm.2015.09.032

Take home message • Normal ECG with h/o shock (not ongoing) could be appropriate shock

• If ECG shows VT helps in localizing VT - uncommon

• Helps in developing appropriate treatment to prevent VT

• Helps in avoiding AICD shocks

• If no arrhythmia and ongoing shocks helps identify device/lead problems, disable device with magnet with external monitoring

• May detect new arrhythmias like AF helps in management – OAC, reprogramming of device

• May detect hyperkalemia

Emergency department evaluation of patients with ICDs and symptoms of acute arrhythmia or

ICD shocks.

William G. Stevenson et al. Circulation. 2004;110:3866-3869

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