Pacemaker & Anaesthesia

Speaker: Dr. Rajesh Choudhuri, PGT Moderator: Dr. V. Majumder, Asst. Prof.

Dept of Anaesthesiology

History

• Battery-operated pacing devices were introduced by C. W. Lillehei (a cardiothoracic surgeon) and Earl Bakken (an electrical technician) in 1958.

• In 1960, Wilson Greatbatch, an engineer in Buffalo, New York, created the first implantable battery-powered device.

• Invention of the implantable cardioverter-defibrillator (ICD * ) around 1980 by Michael Morchower (of Baltimore).

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Pacemakers Today• Single or dual chamber.• Multiple programmable features,• Adaptive rate pacing.• Programmable lead configuration.Internal Cardiac Defibrillators (ICD)• Transvenous leads.• Multiprogrammable• Incorporate all capabilities of contemporary

pacemakers.• Storage capacity.

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Permanent Pacing Indications• Complete heart block• Chronic Bifascicular and Trifascicular Block.• AVHB after Acute MI.• 2nd degree heart block / Mobiz type 2• Hypersensitive Carotid Sinus and Neurally Mediated Syndromes.• Sick sinus syndrome( Sinus Node Dysfunction)• Stroke Adams syndrome.

Indications for ICDs• Cardiac arrest due to VT/VF not due to a transient or reversible cause.• Spontaneous sustained VT.• Syncope with hemodynamically significant sustained VT or VF

Pacer malfunction symptoms

1. Vertigo/Syncope*Worsens with exercise

2. Unusual fatigue3. Low B/P/ peripheral pulses4. Cyanosis5. Jugular vein distention6. Oliguria7. Dyspnea/Orthopnea8. Altered mental status

Anesthesia for Insertion• MAC– To provide comfort– To control dysrhythmias– To check for proper function/capture

• Have external pacer/Isoproterenol/Atropine ready

• Continuous ECG and peripheral pulse.• Pulse ox with plethysmography to see

perfusion of each complex.

Preoperative Evaluation :• Indication for implanted pacemaker/ICD

– Sustained /intermittent tachyarrhythmia or bradyarrhythmias.– Heart failure

• Type of device:• Clinical indication of the device• Appraisal of patient’s degree of dependence on the devices(for patient

requiring pacing for bradyarrhythmias)• Assessment of device function,

– A preoperative history of vertigo, pre syncope, or syncope in a patient with a pacemaker could reflect pacemaker dysfunction.

– A 10% decrease in heart rate from the initial heart rate setting may reflect battery depletion.

– An irregular heart rate could indicate competition of the pulse generator with the patient's intrinsic heart rate or failure of the pulse generator to sense R waves.

• Continue antiarrythmic drug and other cardiac drugs as mandated • Consider Electromagnetic and Mechanical Interference (EMI)

Monitoring• Manual pulse palpation• Pulse oximetry• Continuous ECG monitoring• Auscultation of heart sounds• Intra-arterial blood pressure

Investiagtion:• Routine investigation along with s. electrolytes/acid –

base analysis.• Chest xray:

– Location and external condition of pacemaker electrodes.– If bi-ventricular pace maker(position of coronary sinus lead

when insertion of central line or PA catheter planned ).

Management of a Patient --Intra Operatively

• Application of magnet over pulse generator of pace maker…no longer an acceptable practice.

• Results in asynchronous fixed rate.(chance of R on T phenomenon)

• But Difficult to assess the effect of magnet on cardioverter- defibrilator.

• Transcutaneous pacing is always kept ready.• Rate responsive pacemakers should have rate responsive

mode disabled before surgery.• Central venous catheterisation: chance of pacing leads

dislodgement.

Factors affecting the pacing threshold

Increase threshold• 1-4 wks after implantation• MI• Hypothermia/Hypothyroidism• Hyperkalaemia/acidosis/

alkalosis• Antiarrhythmics(class

1a,1b,1c)• Severe hypoxia/hyperglycemia• Inhalational –local

anaesthesia

Decrease threshold• Increases catecholamines• Stress,anxiety

• Sympathomimetic drugs

• Anticholinergics

• Glucocorticoids• Hyperthyroidism

• Hypermetabolic status

Choice of Anaesthesia

• Technique may not influence directly but physiological changes (acid-base,electrolytes) & hemodynamic shifts ( heart rate, rhythm, hypertension, coronary ischemia) can change CIED function& adversely effect patient outcome.

Effects of Anaesthetic Drugs• Drugs that causes hyperkalemia (increases the

pacemaker threshold) like sch which also may inhibit a normally functioning cardiac pace maker by causing contraction of skeletal ms groups (myo potentials)that the pulse generator could interpret as intrinsic R wave.

• If SCH to be used defasiculating dose of non depolarizing ms relaxants should be given prior to this.

• Etomidate and ketamine should be avoided as these cause myoclonic movements.

• Chance of dislodgement of pacemaker leads by positive pressure ventilation or nitrous oxide entrapment in the pacemaker pocket

Factors affecting CIED FUNCTION---Electro cautery/ MRI /Radio frequency ablation

Effect of MRI on pacemaker• Inhibition of pacing• Asynchronous pacing• Inappropriate defibrillation /complete device

failure• Shielding reduces problems now a days.

Effect of Cautery on Pacemaker

• Mainly coagulation setting in mono ploar cautery than the cutting.

• Bipolar & ultrasonic harmonic scalpel less likely, mono polar effects more.

• Use cautery with low current ,short burst, avoid using in the area of pulse generator and electro leads.

• Use of cautery at least 15 cm from the pulse generator, 1 sec burst with 10-15 sec gap.

• Grounding electrodes for electrocautery should be as far as possible from pulse generator.

• Patient under going lithotripsy keeping the focus of lithotripsy beam away from pulse generator.

• Radiation field: chance of pace maker failure & runway pace maker..

• ECT Therapy: – anti tachycardia function should be suspended.– Myopotential during seizure may inhibit pacemaker

activity.• Peripheral nerve stimulators /evoked potential

monitors/shivering/medication induced ms fasciculation also cause pacemaker interference.

• If emergency defibrillation needed ,keep the defibrillator away( 12 cm) from the pulse generator & lead system(antero-posterior direction pads).

Post Operative Management

• Interrogating the device & restoring baseline settings( like anti tachycardia therapy).

• Cardiac rate ,rhythm monitoring continuously, Hypothermia prevention.

• Reprogramming.

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Pace maker failure1. Failure to pace2. Failure to capture3. Undersensing / failure to sense4. Oversensing

Pace maker failure

THANK YOU