1.37k likes | 4.78k Views
ANAESTHETIC MANAGEMENT OF A PATIENT WITH A PACEMAKER. Dr. Vandana Talwar Senior Specialist & Associate Professor VMMC and Safdarjang Hospital, New Delhi. www.anaesthesia.co.in anaesthesia.co.in@gmail.com.
E N D
ANAESTHETIC MANAGEMENT OF A PATIENT WITH A PACEMAKER Dr. Vandana Talwar Senior Specialist & Associate Professor VMMC and Safdarjang Hospital, New Delhi www.anaesthesia.co.in anaesthesia.co.in@gmail.com
Artificial pacemakers are electronic devices that stimulate the heart with electrical impulses to maintain or restore a normal heart beat in patients with arrhythmias
Pacing lead Pulse generator Electrodes (heart muscles)
Power source (thin metal box) • Lithium iodine battery • 4-10 years • Low rate of self discharge • Electrical circuits • Pacing circuit • Sensing circuit • Implanted / External
Flexible insulated metal wire or lead • Ni, Co, Cr, Mb, Fe • Unipolar • Negative electrode (cathode) – RA / RV • Positive electrode (anode) – pulse generator • Works if anode is in contact with the body • Bipolar • ‘pos’ and ‘neg’ are in the paced chamber • Coaxial
THRESHOLD R-WAVE SENSITIVITY
THRESHOLD • Lowest amount of energy that will stimulate the heart and produce a paced impulse • Acute threshold • Chronic threshold • Lower the threshold – longer the life
R-wave sensitivity • Voltage (mv) required to activate the generator’s sensing circuit to inhibit / trigger the pacing circuit • Permanent non-programmable PM – 2mv
Acquired AV block • Third degree and advanced second degree block Symptomatic bradycardia Drugs sympt bradycardia Asystole > 3 sec or escape rate < 40 beats / min Acute MI Postoperative AV block After catheter ablation of AV junction
Chronic bifascicular and trifascicular block Intermittent 3° AV block Type II 2° AV block • Sinus node dysfunction Symptomatic bradycardia Symptomatic chronotropic incompetence • Hypersensitive carotid sinus syndrome and neurocardiogenic syncope
First position : chamber being paced Second position : chamber being sensed A : Atrium V : Ventricle D : Dual O : Neither, PM switched off / asynchronous mode
Third position : mode of sensing I : Inhibition T : Triggering D : Dual O : Neither
Inhibition • Most common • Sensed event will inhibit the PM • If no sensed event impulse • Eliminates competition • Energy sparing • Diathermy inhibition
Fourth position Programmable Rate adaptive function – designed to raise or lower the pacing rate to help meet the body’s need during physical activity or rest Fifth position Antitachycardia function
Most widely used • At flutter/AF and heart block or long ventricular pauses • Not recommended • Sinus node disease (chronic AF) • AV block • Pacemaker syndrome • Loss of AV synchrony
AV block • Sinus node disease • Carotid sinus syncope • 2 pacing leads • RA appendage • RV apex • Atrial event will inhibit or trigger a ventricular response
Advantages • Maintains AV synchrony • Preserves atrial contribution to preload (áCO – 34%) • Disadvantages • Pacemaker mediated reentrant tachycardia
Asynchronous / non-sensing mode (AOO, VOO, DOO) • Fixed rate pacing • Rarely used Advantages • Not inhibited by diathermy • Useful to cover surgery Disadvantages • Competition – R on T vent arrhythmias • Wastes energy
Synchronous / sensing mode • Demand pacing • No competition • 2 circuits • Impulse formation • Sensing circuit • Inhibited / triggered • Diathermy interpreted as cardiac activity
Temporary bradyarrhythmia (MI, cardiac surgery) • Before permanent pacing for a life threatening bradyarrythmia • Elective replacement of permanent PM • During surgical procedures
Leads introduced subclavian / jugular / femoral • RA / RV under fluoroscopy • Bipolar • Pacing leads are more rigid (J shaped)
TRANSCUTANEOUS (EXTERNAL PACING)
Rapid, safe, easy to initiate • Large self adhesive surface patch electrodes (8cm) • Advantages • Before transvenous / permanent • Disadvantages • High threshold • Severe chest pain
History • CAD – 50% • HT – 20% • DM – 10% • Drug history (digoxin, antiarrythmics) • Indication for PM implantation • Return of pre PM symptoms (vertigo, syncope)
When was it implanted and last checked • Factory preset rate • Battery status (10% reduction in rate) • What type of generator (I-Card) Pacing mode, stimulation threshold, sensing function • S/S cerebral hypoperfusion when exercising muscles around generator