PACEMAKER.pptx BY DR MD B MANUAR

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Anesthesia and Pacemaker

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ANAESTHETIC MANAGEMENT OF A PATIENT WITH PACEMAKER:

SPEAKER-DR. MD BABRAK MANUAR 2 ND YR PGT MODERATOR-DR. SAIKAT MAJUMDaR ASSISTANT PROFESSOR DATE-29/05/2013 ANAESTHETIC MANAGEMENT OF A PATIENT WITH PACEMAKER

INTRODUCTION:

INTRODUCTION Many patients live with pacemaker. No definite figures are available for India - but number is increasing. More and more patients with pacemaker come to us for non cardiac surgery. For the sake of safe anesthetic management we should know- The modes of pacing. Their indications & contraindications. Treatment strategies in case of per operative failure.

WHAT IS PACEMAKER????:

WHAT IS PACEMAKER???? It also called artificial pacemaker- so don’t confuse with natural pacemaker of heart. Artificial pacemakers are electronic devices that stimulate the heart with electrical impulses to maintain a normal heart beat in patients with arrhythmia.

FUNCTIONS OF PACEMAKER:

FUNCTIONS OF PACEMAKER Stimulate cardiac depolarization. Sense intrinsic cardiac function. Respond to increased metabolic demand of body by providing rate responsive pacing.

COMPONENTS OF PACEMAKER:

COMPONENTS OF PACEMAKER Pulse generator. Pacing lead. Electrode.

COMPONENTS OF PACEMAKER:

COMPONENTS OF PACEMAKER Pulse generator : contains the electric circuit and battery for energy supply Electrode : the metal portion of lead in direct contact with myocardium Lead : insulated wire that extends from pulse generator to electrode

PULSE GENERATOR:

PULSE GENERATOR Implanted subcutaneously or in sub muscular space. Lithium battery- Power source. Life span-5 to 10 yrs. Electronic circuit- Pacing circuit Sensing circuit Timing circuit

PACING LEAD:

PACING LEAD Flexible insulated metal wire connecting pulse generator & electrodes. Unipolar- Negative electrode-in RA/RV. Positive electrode-in pulse generator. Pacing spikes are large- as current travel long distance. Bipolar- Both positive & negative electrode are in the paced chamber. Pacing spike are very small as current travel less distance.

ELECTRODE:

ELECTRODE An exposed metal end of the lead in contact with the endocardium or epicardium. Has both stimulating & sensing functions. Steroid eluting- prevent tissue reaction around electrode tip.

PACEMAKER CODE DEVELOPED AS JOINT PROJECT BY NORTH AMERICAN SOCIETY OF PACING & ELECTROPHYSIOLOGY (NASPE) AND BRITISH PACING AND ELECTROPHYSIOLOGY GROUP (BPEG) - REVISED 2002:

PACEMAKER CODE DEVELOPED AS JOINT PROJECT BY NORTH AMERICAN SOCIETY OF PACING & ELECTROPHYSIOLOGY (NASPE) AND BRITISH PACING AND ELECTROPHYSIOLOGY GROUP (BPEG) - REVISED 2002 I CHAMBER PACED II CHAMBER SENSED III RESPONSE IV PROGRAMMABILITY V TACHYCARDIA O=None O=None O=None O=None O=None A=Atrium A=Atrium I=Inhibited C=Communicating P=Pacing V=Ventricle V=Ventricle T=Triggered P=Simple programmable S=Shock D=Dual(A+V) D=Dual(A+V) D=Dual(I+T) M=Multiple programmable D=Dual(P+S) R=Rate modulation

PowerPoint Presentation:

First position- chamber being paced. Second position- chamber being sensed. A: Atrium V: Ventricle D: Dual O: None

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Third position: mode of response. I: Inhibiting T: triggered D:Dual O: None

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Inhibition- Most common. Sensed event will inhibit the pacemaker. If no event is sensed – impulse will generated. Eliminates competition. Energy sparing phenomenon. Diathermy – inhibition.

PowerPoint Presentation:

Fourth position- Programmability Rate adaptive function-designed to raise or lower the pacing rate to meet the body’s need during physical activity or rest. Fifth position- Antitachycardia function

CODE INTERPRETATION:

CODE INTERPRETATION If a pacemaker’s code is VVI- Chamber being paced is ventricle. Chamber is being sensed is ventricle. Response mode is inhibition. In the same way if it is AAI- Pacing done at atrium. Sensing is from atrium. Respond to inhibition mode.

MODES OF PACING:

Single chamber pacing Dual chamber pacing Asynchronous pacing Synchronous pacing MODES OF PACING

SINGLE CHAMBER PACING:

SINGLE CHAMBER PACING This require single pacemaker lead. Lead lies only in one chamber(ventricle). Independent of atrial activity. Used in AV conduction disease.

DUAL CHAMBER PACING:

DUAL CHAMBER PACING AV sequential pacing- atria contract first then after a adjustable PR interval ventricle contract. Requires 2 lead-one in atrium & another in ventricle. Prerequisites-Should have non fibrillating atria & intact AV conduction.

ASYNCHRONUOS/NONSENSING MODE :

ASYNCHRONUOS/NONSENSING MODE Pace at preset fixed rate independent of inherent heart rate. Not inhibited by diathermy-useful to cover surgery. Competition- between inherent heart rate and pacemaker. Wastes energy. Rarely used in normal situation.

SYNCHRONUOS/SENSING MODE:

SYNCHRONUOS/SENSING MODE Demand pacing-paced when spontaneous rate falls below preset rate. No competition. Diathermy interpreted as cardiac activity. Magnet application change it to asynchronous mode.

INDICATIONS OF PERMANENT PAEMAKER:

ACCORDING TO ACC/AHA INDICATIONS OF PERMANENT PAEMAKER

ACQUIRED AV BLOCK:

ACQUIRED AV BLOCK A)3rd˚ AV block: Symptomatic bradycardia. Drug- causing symptomatic bradycardia. Post operative AV block. Neuromuscular disease with AV block. Asystole> 3 seconds or escape rhythm<40bpm. B)2 nd ˚ AV block: Permanent or intermittent symptomatic bradycardia.

PowerPoint Presentation:

After Myocardial infarction: Symptomatic 2 0 AVB or 3 0 AVB. Infranodal AV block with LBBB. Bifasicular or trifasicular block: Intermittent complete heart block with symptoms. 2nd˚ AV block. Bundle branch block.

PowerPoint Presentation:

Sinus Node Dysfunction: With symptoms as a result of long term drug therapy. Symptomatic chronotropic incompetence. Hypersensitive carotid sinus & neurocardiac syndromes: Recurrent syncope associated with carotid sinus stimulation. Asystole of > 3 sec duration in absense of any medication.

TEMPORARY CARDIAC PACEMAKER:

TEMPORARY CARDIAC PACEMAKER Indications: Temporary bradycardia(MI, cardiac surgery) Before permanent pacing for life threatening bradycardia. Elective replacement of permanent pacemaker. During surgical procedure. Types: Trans venous Trans cutaneous

TRANS VENOUS TEMPORARY PACING:

TRANS VENOUS TEMPORARY PACING Leads introduced through subclavian/ jugular /femoral vein. RA/RV under fluoroscopy guided. Leads are bipolar rigid and J shaped.

TRANS CUTANEOUS TEMPORARY PACING:

TRANS CUTANEOUS TEMPORARY PACING Rapid, safe & easy to initiate. Electrodes are large self adhesive surface patch type. Advantage- before trans venous/permanent pacing. Disadvantage- Threshold is high. Severe chest pain

THRESHOLD:

THRESHOLD The lowest amount of energy that will stimulate the heart & produce a paced impulse. Measured in terms of amplitude and duration. Amplitude is programmed in volts or in milliamperes. Duration is measured in milliseconds. Lower the threshold –longer the life of battery.

FACTORS AFFECTING THRESHOLD:

INCREASED DECREASED 1-4 wks after implantation. Myocardial ischemia/infarction. Hypothermia, hypothyroidism. Hyperkalemia, acidosis/alkalosis. Antiarrhythmics Severe hypoxia/hyperglycemia Increased catecholamine's stress, anxiety. Sympathomimetic drugs. Anticholinergics Glucocorticoids Hyperthyroidism Hyper metabolic status. FACTORS AFFECTING THRESHOLD

SENSITIVITY:

SENSITIVITY Voltage (mv) required to activate the pulse generator’s sensing circuit to inhibit or trigger the pacing circuit. Permanent nonprogrammable pace maker it is 2mv.

IMPLANTABLE CARDIOVERTER DEFIBRILATOR(ICD):

IMPLANTABLE CARDIOVERTER DEFIBRILATOR(ICD) Battery powered device consist of pulse generator and lead for tachyarrhythmia detection and therapy. It provides- Antitachycardia and antibradycardia pacing. Synchronised or nonsynchronised shocks. Even stores electrogram and history logs.

ICD-HOW IT WORKS?:

ICD-HOW IT WORKS? Measures each R-R interval. Categorize the rate (normal, too fast or too slow) If sufficient number of short R-R interval within in a period of time– it will declare tachycardia episode Based on the programmed algorithm- internal computer decide between antitachycardia pacing and shock.

ICD-SETTINGS:

ICD-SETTINGS Usually gives a shock of 25 joule. Takes 5-20 seconds to sense VT/VF. Takes another 5-15 seconds to charge. Delay 2.5-10 seconds before next shock is administered. Total 5 shocks in a episode then pauses. It sense cautery as VF and deliver shock. Magnet application disable its antitachycardia function. If CPR needed- wear rubber gloves for insulation.

ICD(CONT..):

ICD(CONT..) Indications- Recurrent VT/VF-not responding to medical therapy. Spontaneous sustained VT with structural heart disease. 2/3 rd of patients still require medical therapy. Cost is high. Survival rate is similar.

GENERIC DEFIBRILLATOR CODE(NASPE/BPEG):

GENERIC DEFIBRILLATOR CODE(NASPE/BPEG) Letter I Shock chamber Letter II Antitachycardia pacing chamber Letter III Tachycardia detection chamber Letter IV Anti bradycardia pacing chamber O= None O= None E= Electrogram O= None A= Atrium A= Atrium H= hemodynamic A= Atrium V= Ventricle V= Ventricle V= Ventricle D= Dual (A+V) D= Dual (A+V) D= Dual (A+V)

PREOPERATIVE EVALUATION:

HISTORY EVALUATION OF PACEMAKER EXAMINATION INVESTIGATION PREOPERATIVE EVALUATION

HISTORY:

HISTORY Detailed of underlying cardiovascular disease responsible for pacemaker insertion. Associated medical problem- CAD, HT, DM Preimplantation symptoms- lightheadedness, dizziness or fainting. Evaluation of cardiac status- dobutamine stress test.

EVALUATION OF PACEMAKER:

EVALUATION OF PACEMAKER When implanted and last checked. Manufacturer preset rate. Battery status- 10% reduction from initial rate suggests depletion of battery. Manufacturer identification card- pacing mode, stimulus threshold and sensing function. Examination for scar , palpation of device .

EXAMINATION:

EXAMINATION Pulse- regular or irregular (competition). Blood pressure. Bruits Sing and symptoms of congestive cardiac failure. Location of generator. Consciousness level.

INVESTIGATIONS:

INVESTIGATIONS Routine biochemical and hematological investigation, coagulation screening. Serum electrolyte measurement(specially k+ level) . Well penetrated chest X-ray- model number of pacemaker (radio opaque marker), integrity and position of leads. Baseline 12-lead ECG- No or intermittent pacing spike- own rhythm . Pacing spike before every beat- PM dependent.

PREOPERATIVE PREPARATION:

PREOPERATIVE PREPARATION Determine whether EMI is likely to occur during the procedure. Temporary reprogramming to asynchronous mode. Suspend antitachyarrhythmia functions in case of ICD. Advice surgeon to use bipolar electrocautery or ultrasonic scalpel. Temporary pacing and defibrillator should be kept ready. Emergency drug like atropine, isoprenaline . Magnet should available.

CHOICE OF ANAESTHESIA:

CHOICE OF ANAESTHESIA Based on the underlying disease. Regional- No guideline favoring or contradicting. Paced heart cannot compensate hypotension by tachycardia- used cautiously. General anaesthesia - Both narcotics and inhalational are safe. Etomidate , ketamine should avoided. Avoid shivering due to perioperative hypothermia. Succinylcholine should avoided. Nondepolarising muscle relaxant is safe.

INTRAOPERATIVE MONITORING:

INTRAOPERATIVE MONITORING Pulse oximeter- specially the plethesmograph. NIBP ETCO2 ECG- II & V5 (interference) IBP-based on surgery. Pulmonary artery catheter-caution (can dislodge <4wks old) Central venous line- caution. Manual palpation pulse. Capillary refilling. Trans esophageal or precordial stethoscope.

INTRAOPERATIVE MANAGEMENT:

Goal- decrease electro magnetic interference INTRAOPERATIVE MANAGEMENT

MEASURES TO DECREASE EMI:

MEASURES TO DECREASE EMI Bipolar cautery – preferable. Unipolar cautery- Use minimum current. Do not use within 15cm of pulse generator. Limit to 1 sec bursts in every 10secs. Ground plate- Close to operative site. Good skin contact (thigh). Away from pulse generator.

UNIPOLAR DIATHERMY:

UNIPOLAR DIATHERMY Electrical plate is placed under patient and acts as indifferent electrode Current passes between instrument and indifferent electrode

BIPOLAR DIATHERMY:

BIPOLAR DIATHERMY Two electrodes are combined in the instrument (e.g. forceps) Current passes between tips and not through patient

INTRAOPERATIVE PACEMAKER FAILURE:

INTRAOPERATIVE PACEMAKER FAILURE No intrinsic and no PM rhythm Stop diathermy immediately. Apply high powered magnet over pulse generator. Atropine / Isoproterenol / Inotropes . Temporary pacing. Repeated precordial thumps. CPR

EXTERNAL DEFIBRILLATOR:

EXTERNAL DEFIBRILLATOR Use lowest defibrillator current. High energy current-thermal burn. Paddles should be as far as possible away from pulse generator. It should be perpendicular to line between lead and pulse generator. At least 10-15 cm from the pulse generator.

POSITION OF PADDLES:

POSITION OF PADDLES Left or right pectoral implant showing recommended anterior posterior pad placement. Left pectoral implant showing anterior apex pad placement. Lateral view of the anterior posterior pad placement.

PACEMAKER & SPECIFIC SITUATIONS:

PACEMAKER & SPECIFIC SITUATIONS TURP- Coagulation current has no effect. Cutting (high frequency) current can suppress bipolar demand ventricular pacing. Rx-convert preoperatively into asynchronous mode. LITHOTRIPSY- 1. Avoid focusing the lithotripsy beam near the pulse generator. 2. If the lithotripsy system triggers on the R-wave, consider preoperative disabling of atrial pacing.

PowerPoint Presentation:

MRI- MRI is generally contraindicated in patients with PM. If MRI must be performed, consult with the ordering physician, cardiologist, radiologist and pacemaker manufacturer. RADIOTHERAPY- Radiation therapy can be safely performed. Surgically relocate the PM if the device will be in the field of radiation.

PowerPoint Presentation:

RADIOFREQUENCY ABLATION- Advise surgeons to avoid direct contact between the ablation catheter and Pulse generator and leads. Advise surgeons to keep radiofrequency current path far away from Pulse generator and leads. ELECTROCONVULSIVE THERAPY- ECT is safe in patient with pacemaker. But seizure may inhibit pacemaker. ECG monitoring is must. PM should be changed to asynchronous mode.

POSTOPERATIVE MANAGEMENT:

POSTOPERATIVE MANAGEMENT Shivering and fasciculation should be avoided. Ventilation must be controlled and constant. Otherwise change PM to asynchronous mode. Function of pacemaker should be checked before and after initiation of mechanical ventilation.

TAKE HOME MESSAGE:

TAKE HOME MESSAGE Know indication. Know when it was implanted and last checked. Know about types of pacemaker, initial pacing rate and half life of pacemaker battery. Search for manufacturer book and magnet kept with party. If needed assistance from cardiologist and manufacturer representative should be taken.

TAKE HOME MESSAGE:

TAKE HOME MESSAGE Determine whether electromagnetic interference is likely to occur during the procedure. Determine whether reprogramming of pacemaker function needed or not. Suspend anti arrhythmic function of ICD if needed. Advise surgeon to use bipolar electrocautery or ultrasonic scalpel. Be sure about the availability of temporary pacing, defibrillator and drugs for resuscitation.

TAKE HOME MESSAGE:

TAKE HOME MESSAGE Monitor ECG with interference. Frequently check for pulse. If unipolar diathermy is to be used- Ground plate should close to operative site and away from pulse generator and close contact with skin. Diathermy should not be used within 15 cm from pulse generator. Frequency should be 1 second burst in every 10 seconds. Use minimum current.

TAKE HOME MESSAGE:

TAKE HOME MESSAGE Avoid drugs that cause myoclonic activity or fasciculation. Avoid hypothermia and shivering. Central venous line or pulmonary artery catheter should be used with caution.

PowerPoint Presentation:

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