Pacemakers, Implanted Defibrillators & Anaesthesia
Practical Guidelines
Introduction
Pacemakers and implantable defibrillators (ICD) are inserted into patients for a wide variety of cardiac conditions. Rhythm disturbances are the most common indication but pacemakers are also used in patients with poor ventricular performance.
The majority of pacemakers operate with some form of electrical sensing to prevent inappropriate pacing over a natural rhythm. The electrical interference generated by the use of surgical diathermy may be sufficient to inhibit the pacemaker and lead to a failure of effective pacing.
Despite this most pacemakers are very robust and will recover from brief periods of electrical interference without a problem. The effect of placing a magnet over the pacemaker is very variable, some will switch to a non-sensing mode others may switch to end-of-battery life mode. Switching to a non-sensing mode may appear to be reassuring in the presence of monopolar diathermy but exposes the patient to the much greater risk of ventricular fibrillation.
Implanted defibrillators may present serious problems for staff and patients and should be treated with great respect.
Elective Procedures
The majority of patients will carry a card giving details of the pacemaker or ICD that they have along with the date of insertion. This information should be given to the Cardiac Physiologist from the Cardiology department so that they can bring the correct equipment.
If a patient has had a recent pacemaker check (ie in the last 3 months) and a copy of that is available there is no need for a further check. If however there is any concern over the pacemaker function then
on admission the patient should be seen by a Cardiac Physiologist or their equivalent who will check the pacemaker function and advise if any adjustments are required. The majority of devices will not require any changes prior to or after surgery.
Patients with an ICD must be seen prior to surgery. Depending on the site of the surgery to be performed the ICD may need to be deactivated. Advice about the necessity for this should be obtained from the patient’s Implant or Follow-up centre. Arrangements should be made to reactivate the ICD post-operatively if de-activated.
The anaesthetist and the surgeon involved should discuss the implications of a pacemaker or an ICD prior to the case starting. If necessary the case should be discussed with a senior colleague and advice obtained from the implant or follow-up centre..
Facilities for full cardiopulmonary resuscitation must be immediately available including an external defibrillator. Where an ICD is present and deactivated, remote external defibrillator pads should be used if access to the anterior chest wall will interfere with the surgery or the sterile field. In the very unlikely event of a prolonged, life-threatening arrhythmia conventional advanced life support procedures should be followed.
Where possible either diathermy should be avoided or bipolar diathermy should be used. If this is not possible then the monopolar return pad should be positioned so that diathermy current passes as far away from the pacemaker and its leads as possible.
ECG monitoring should start before induction of anaesthesia and should continue until correct functioning of the pacemaker has been confirmed post-operatively, preferably by a Cardiac Physiologist.
Where the mode exists the ECG monitor should be switched to Paced mode. In the unlikely event of a failure to capture the ECG may misinterpret the pacing spikes as QRS complexes and will continue to display a heart rate when the patient is in asystole.
An alternative method of detecting a pulse such as a pulse oximeter or an arterial line must be used.
If detectable pacemaker inhibition occurs with diathermy the surgeon should be informed immediately and the steps described above taken to reduce the effects. If monopolar diathermy has to be used extensively to control the bleeding and pacing is significantly affected then an external magnet may be tried as a last resort.
A small number of patients are fitted with a rate sensitive pacemaker with minute volume detection. These pacemakers may not perform properly during mechanical ventilation and may be affected by respiratory monitoring using impedance plethysmography via the ECG electrodes. This mode can be switched off by the Cardiac Physiologist.
Emergency Procedures
Wherever possible the steps outlined above should be followed in emergency cases as well.
Where it is not possible to get the pacemaker checked before surgery the simple steps outlined above should be followed. Pacemaker function should be checked as soon as feasible post-operatively.
Key Points
- Patients with permanently implanted pacemakers or defibrillators are increasingly presenting for elective or emergency surgery under general, regional and local anaesthesia
- Pacemakers are highly sophisticated and robust and in most cases should not need any adjustment either before, during or after surgery and anaesthesia
- Where possible bipolar diathermy should be used. Where monopolar diathermy has to be used this should be limited to short bursts if pacing is affected
- Implanted defibrillators may need to be de-activated prior to surgery and an alternative means of external defibrillation made available