PERIOPERATIVE MANAGEMENT: CARDIAC PACEMAKERS AND DEFIBRILLATORS DR SUSAN CORCORAN CARDIOLOGIST
ONCE UPON A TIME.. Single chamber pacemakers Programmed at 70/min VVI 70
UNIPOLAR SYSTEMS A Unipolar Pacing System Contains a Lead with Only One Electrode Within the Heart. In this system the impulse: Flows through the tip electrode (cathode) Stimulates the heart Returns through body fluid and tissue to the Pulse generator (anode) Anode + _ Cathode
BIPOLAR SYSTEMS A Bipolar Pacing System Contains a Lead with Two Electrodes Within the Heart. In this system the impulse: Flows through the tip electrode located at the end of the lead wire Stimulates the heart Returns to the ring electrode above the lead tip Anode Cathode
NOW.. DDD(R) or DDI or AAI>DDD CRT-P Dual Chamber Pacemaker RV septal lead position Biventricular Pacemaker
AND THERE S MORE CRT-D Implantable loop recorders ICD
GENERAL RULES OF PROGRAMMING Pacemakers are programmed to pace the ventricle as little as possible Defibrillators are usually programmed to never pace the ventricle unless there is a pacing indication. Biventricular devices (most of these are defibrillators) are programmed to ALWAYS pace both ventricles.
UNFORTUNATELY. There is no one size fits all for perioperative management of a patient with an implanted cardiac device.
AIM TO PREVENT THESE
- BUT ALSO TO UNDERSTAND THESE
WHAT DO I WANT TO AVOID? Failure to deliver pacing, defibrillation, or both Changes in pacing behaviour Inappropriate delivery of a defibrillator shock (if an ICD is present) Damage to the device, the leads, or site of lead implantation Inadvertent electrical reset to backup pacing modes Stone ME et al. British Journal of Anaesthesia 107 (S1): i16 i26 (2011)
ELECTROMAGNETIC INTERFERENCE
WORST CASE SCENARIO? Unipolar pacemaker with unipolar diathermy with current pacing crossing the device
OPERATIVE FACTORS TO MINIMISE THE RISK OF INTERFERENCE BY DIATHERMY Use bipolar diathermy whenever possible When using unipolar diathermy place the indifferent plate to direct current away from the current path of the pacemaker Ensure the indifferent plate is firmly applied Minimise bursts of unipolar diathermy to <5 seconds particularly when operating in close proximity to the device, or the device has a unipolar lead configuration. Procedures performed below the diaphragm in patients with bipolar pacing configurations are low risk for interference Stone ME et al. British Journal of Anaesthesia 107 (S1): i16 i26 (2011) Crossley JH et al. Heart Rhythm. 2011 Jul;8(7):1114-54.
RATE RESPONSE Accelerometer +/- Minute Ventilation Closed Loop Stimulation
OTHER EMI INTERFERENCE - MINUTE VENTILATION RATE RESPONSE SENSORS
FUNNY PACING ALGORITHMS
PACING ALGORITHMS TO MINISMISE VENTRICULAR PACING AV search AAI to DDD AV block detected
AUTOMATIC THRESHOLD AND IMPEDANCE TESTING Automatic Impedance testing Automatic ventricular threshold testing
PACING TOO FAST? Specialised algorithm for the management of vasovagal syncope Atrial fibrillation pre and post mode switching DDD>DDI Mitrani,R.D. and others,cardiac Pacemakers,Hurst's The Heart,10th edition,vol.1,pp.963-992
PACING TOO SLOW? Hysteresis Sleep and Rest Rates
HRS GUIDELINES FOR PREOP DEVICE EVALUATION.. Crossley JH et al. Heart Rhythm. 2011 Jul;8(7):1114-54.
WHAT DO I NEED TO KNOW FOR PERIOPERATIVE DEVICE MANAGEMENT? PATIENT FACTORS Why does the patient have the device? What device does the patient have? Is the patient pacemaker dependent? How is the device programmed? Brady and tachy therapies. When was the pacemaker last checked? What funny algorithms might make me worry?
WHAT DO I NEED TO KNOW FOR PERIOPERATIVE DEVICE MANAGEMENT? OPERATIVE FACTORS Where is the surgery in relation to the device? What might cause abnormal device behaviour in the perioperative period? Does the device require checking preoperatively? Does the device require reprogramming for the operation? Can I just use a magnet?
MAGNET OPERATION Pacemakers Defibrillators Asynchronous pacing single or dual chamber depending on programming rate between 80-100/min depending on manufacturer can revert to programmed rate Tachycardia therapies disabled No change to bradycardia therapies Healy JS et al. Canadian Journal of Cardiology 28 (2012) 141 151
MOST OF THE TIME REPROGRAMMING IS NOT NECESSARY A MAGNET IS FINE Risks of reprogramming a device Have to have someone available to reprogram it postoperatively need to stay in a monitored environment until this is done Might not be reprogrammed before discharge tachycardia therapies remain programmed off or asynchronous pacing stays programmed on. Proarrhythmia from asynchronous pacing Can t use the device to manage arrhythmias should they occur
WHEN TO CONSIDER REPROGRAMMING Patient/Device factors Pacemaker dependent +/- defibrillator and cannot readily access the device during the procedure. Minute ventilation rate response sensor Operative factors: Unipolar diathermy Surgery involving the upper body (<15cm from the device) Radiofrequency ablation long duration of current application Lithotripsy triggered to R wave ECT Patient position precludes easy access with a magnet
INTRAOPERATIVE MANAGEMENT AP placement of patches for defibrillation or external pacing Indifferent plate positioned to direct current away from the device Magnet available may be taped to the patient if defibrillator functions to be suspended Healy JS et al. Canadian Journal of Cardiology 28 (2012) 141 151 Pulse wave monitoring Pulse oximeter or arterial line
DEVICE CHECK POST-OP? Checking of a device in the immediate post-op period is not necessary unless: The device was reprogrammed pre-op Radiofrequency ablation has been used Patient required external cardioversion You saw unusual device behaviour during the procedure In which case the device must be checked whilst the patient remains monitored in recovery. In most cases: Routine follow-up is fine Device check predischarge if the patient has undergone Lithotripsy or ECT or unipolar diathermy above the diaphragm has been used. Crossley JH et al. Heart Rhythm. 2011 Jul;8(7):1114-54 Stone ME et al. British Journal of Anaesthesia 107 (S1): i16 i26 (2011)
SUMMARY Most of the time the pacemaker or defibrillator does not require reprogramming a magnet will be fine May help to develop a proforma to send through to cardiologists/pacemaker clinics with the information you require. If in doubt a post op pacemaker check is a god idea.