Implantable Cardioverter Defibrillators & End of Life Anna Wilson Cardiac Physiologist Waikato Hospital

ICD Operations

Pacemaker and ICD Clinics

Travelling Clinics Pacemaker and ICD patients Taupo 132 patients = 32 ICDs Rotorua 234 patients = 49 ICDs Gisborne 166 patients = 65 ICDs Thames 265 patients = 47 ICDs New Plymouth 298 patients = 85 ICDs Waikato patients 2,447 = 569 ICDs ICDs = 24%

Inventor of the ICD Michel Mirowski, M.D

First Clinical Model Short battery life Shock only 280g Large device Non-programmable Epicardial patch electrodes Abdominal implant Required thoracotomy

Development Small Device Pectoral Implant Usually fully endocardial implant endocardial implant Active ‘Can’

Pacemaker and ICD leads Screw-in (active fixation) pacemaker lead Tined (passive fixation) pacemaker lead ICD lead (active fixation) External shock coil

Implantable Cardioverter Defibrillator (ICD)

Who Benefits from ICD Therapy

Trials Secondary Prevention Trials: In survivors of VT/VF arrest Outcome  ICDs reduced the risk of sudden death over antiarrhythmic drugs Primary Prevention Trials: Who is at risk of a life threatening ventricular arrhythmia? Outcome  ICDs reduced risk of death in heart attack survivors Outcome  ICDs save lives in heart failure and reduced EF

ICD – Implantable Cardioverter Defibrillator Primary indication (prevent SCD): Prophylactic ICD for people at risk of a VT/VF arrest. (NYHA II or III heart failure, EF ≤35%) Secondary indication: For people that have survived a VT/VF arrest. Patients with cardiac conditions associated with high risk of sudden death with unexplained syncope (likely due to ventricular arrhythmia)

Heart Failure Decreased haemodynamic function, exercise tolerance and QoL due to poor LV function. Risk for SCD ICDs  improved outcome and reduction in all cause mortality Heart failure patients with a wide QRS have poor prognoses Mechanical Dyssynchrony

CRT - Cardiac Resynchronisation Therapy

LBBB Wide QRS (>120ms), deep Q/S wave V1, ascending ST elevation V1-V3, deformed QRS pattern (‘M’) V6 followed by negative T wave

CRT - Cardiac Resynchronisation Therapy Used to correct dyssynchrony i.e. Ventricular electromechanical delay - LV and RV not contracting in sync i.e. Ventricular electromechanical delay - LV and RV not contracting in sync Criteria: LVEF ≤35%, SR with LBBB and QRS ≥150ms, NYHA Class II-III. Reduce heart failure symptoms LV Remodelling Pacemaker (CRT-P) or pacemaker and ICD (CRT-D)

CRT – Defibrillator Trials CRT-D Trials:  Reduction in heart failure events, hospitalisation and death  Symptom and haemodynamic improvement in HF patients with low EF, poor pump and wide QRS

MADIT-CRT (long term follow-up) CRT-D implanted in HF patients with LBBB had 41% reduced risk of death compared to conventional ICD. CRT-D had a 5 year survival rate of close to 90%. >80% of CRT-D patients were still alive at 7 years. CRT patients experienced a 62% relative risk reduction in experiencing first HF event MADIT-CRT Multicentre Automatic Defibrillator Implantation with Cardiac Resynchronisation Therapy

ICD Therapies ICDs deliver a range of therapies Bradycardia pacing (it is a pacemaker) Tachycardia pacing (ATP) Cardiac resynchronisation therapy Cardioversion shocks (low energy) Defibrillation shocks (high energy)

Typical ICD settings: 1-3 zones ATP = anti-tachycardia pacing

How many shocks? Usually programmed to deliver 6-8 shocks and then will stop therapy If the rate slows and then speeds up again this will be treated as a new episode i.e. 6-8 shocks could be delivered again i.e. 6-8 shocks could be delivered again

Pacing post a 35J shock

ATP – anti tachycardia pacing Rapid burst of pacing to try and revert rhythm Often several sequences are programmed on If successful shocks will be diverted

ATP successful and prevents a shock ATP VT SR

Inappropriate shocks Rapid AF most common cause Sinus/atrial tachycardia (regular rhythm with1:1 A to V relationship) SVT Abnormal sensing (internal or external) Lead fracture Medications: Important and shouldn’t be changed without consultation with a Cardiologist

Electromagnetic Interference (EMI) Strong electromagnetic fields can interfere with ICDs. Oversensing  Inappropriate shocks!

Base rate pacing often 40ppm with an ICD Base rate pacing often 40ppm with an ICD VVI pacing 40ppm and external pacing 70ppm – sensed as VF by ICD and shocks received Intrinsic rhythm (slow) External pacing sensed as VF and shocks delivered

Can you touch an ICD patient receiving a shock? YES! External shock uses more energy than an internal one External shock uses more energy than an internal one Energy escaping to the surface is difficult to detect and harmless Energy escaping to the surface is difficult to detect and harmless

External Defibrillation Do not withhold therapy for fear of damaging ICD ICDs are designed to withstand external defibrillation but can be damaged Position pads as far away (>10cm) from ICD as possible CPR chest compressions can be performed as usual

Adverse psychological effects of ICD shocks – whether appropriate or inappropriate AnxietyAngerDepression Avoid activities Family members also become anxious Quality of life?

Support group Patient run support group Meet annually Can meet other people with ICDs Arrhythmia Alliance Australia Facebook page: Shock Absorbers

End of Life Increase use of life saving/prolonging devices can extend life Increase use of life saving/prolonging devices can extend life Cardiac disease is often progressive Cardiac disease is often progressive Device likely to be in place at death Device likely to be in place at death Duty of care to preserve the dignity of dying Duty of care to preserve the dignity of dying The ICD clinic needs to know that a patient has been referred to Hospice The ICD clinic needs to know that a patient has been referred to Hospice

Remain in contact with the ICD Clinic Your patient may receive a shock Your patient may receive a shock Shock therapy may need to be deactivated Shock therapy may need to be deactivated - Programmer - Magnet Your patient may die Your patient may die - Device may alarm or vibrate - Plan after death: Marae, cremation

ICD Beeping/Vibrating Alerts ICD Beeping/Vibrating Alerts An audible beep heard or vibration felt by the patient to alert them to phone the ICD clinic Will occur after death if not deactivated Distress to family members Call the ICD clinic – the earlier the better

Pacemaker Patients at End of Life Nothing needs to be done The pacemaker will not keep someone alive or prolong the dying process If pacemaker pulse will not initiate a heart beat in a heart that is electrically inert and mechanically dormant

Magnets A magnet placed over an ICD will stop tachycardia therapy i.e. all shocks and ATP will be suspended Pacing will continue As soon as the magnet is removed tachycardia therapy will resume

When to use a magnet with an ICD In theatre when diathermy is being used (patient must be monitored throughout) If a patient is receiving inappropriate shocks (e.g. AF, lead fracture) If a patient is receiving appropriate therapy but patient is conscious and haemodynamically stable (e.g. slow VT) To stop ICD therapies in a dying patient IF IN DOUBT DO NOT USE check with a Cardiologist

Position of Magnet over ICD

Turning off ICDs permanently If the patient is at end stage it may be appropriate to have the device turned off to prevent shocks Needs consultation with patient, family, Cardiologist (authorise deactivation) Physiologist can turn off (accompanied by senior nurse if outside of DHB) or use of a magnet Protocol in place

Home Monitors

Plugged into the power and uses either cellular network (predominantly) or landline Communicates with ICD and to a secure internet server Website accessed by the ICD clinic Website accessed by the ICD clinic Alerts us to any serious issues immediately (battery or lead failures, arrhythmias) Advantage for outreach patients as it may save a trip to Waikato

Home monitor send for lead impedances out of range