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By Ahmed M. Shehata Assistant lecturer

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INTRODUCTION 30,000,000 patients worldwide have been implanted pacemakers while 3,000,000- 5,000,000 have a Implantable Cardioverter Defibrillator (lCD). 115,000 new devices are implanted each year in U.S.

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Temporary Pacing Transcutaneous Pacing External electrode pads and power device Large electrodes over precordium & back at level of heart Output: up to 140 mA Terminate: Tachy- arrhythmia Pacing rate: up to 180 bpm Sensing facility (VVI pacing possible) Transcutaneous Pacing External electrode pads and power device Large electrodes over precordium & back at level of heart Output: up to 140 mA Terminate: Tachy- arrhythmia Pacing rate: up to 180 bpm Sensing facility (VVI pacing possible) Transvenous Pacing Electrode placed via femoral, brachial, IJV or subclavian vein 90% success rate in absence of fluroscopy under ECG guidance Atrial J-shaped electrodes and balloon tipped ventricular electrodes Externally paced generator with output up to l0mA All pacing modes available Transvenous Pacing Electrode placed via femoral, brachial, IJV or subclavian vein 90% success rate in absence of fluroscopy under ECG guidance Atrial J-shaped electrodes and balloon tipped ventricular electrodes Externally paced generator with output up to l0mA All pacing modes available

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Temporary Pacing Indications A. Unstable bradydysrhythmias B. Unstable tachydysrhythmias C. Third degree Atrioventricular block Endpoint: resolution of the problem or permanent pacemaker implantation.

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Permanent PACEMAKER Ventricular / Atrial channel transmits the Pacing impulse to the respective lead. Power source, Circuit Electrodes: 1.Uni /Bi polar

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Indication of Permanent Pacing A. Sinus Node Dysfunction - Symptomatic diseases of impulse formation. Sinus bradycardia, sinus pause or arrest, or sinoatrial block. 5O% implantation. B. Atrial Fibrillation - Dual site atrial pacing to decrease intra-atrial conduction time.

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Indications cont.. C. AV Block: Due to ischaemic / congenital / degenerative / inflammatory. Block within HIS Purkinje system. 3rd block with symptomatic bradycardia, documented asystole. Asymptomatic 3rd block, asymptomatic Type II 2nd block, asymptomatic Type I 2nd block. D. Chronic BBB likely to progress to CHB.

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Indications cont.. E. Miscellaneous Hypertrophic Obstructive Cardiomyopathy, Dilated cardiomyopathy, Hypersensitive Carotid Sinus Syndrome & Neurogenic Syncope, Cardiac Transplant, Prolonged QT interval $ LV systolic dysfunction biventricular / septal.

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Generic Pacemaker Codes The North American Society of Pacing and Electrophysiology (NASPE) and British Pacing and Electrophysiology Group (BPEG) Pacemaker codes.

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Position III: Response to Sensing I (Inhibited): The chamber is paced unless intrinsic electrical activity is detected during the pacing interval. T (Triggered): The pacing device will emit a pulse only in response to sensed event. D (Dual): Provides AV synchrony. Pacing device emits atrial pulse if no sensed atrial event takes place, once an atrial event has occurred, the pacing device will ensure that a ventricular event follows.

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Position IV: Programmability Vibration sensor Motion sensor Minute ventilation sensor the sensor detects exercise, it increases the pacing rate (termed sensor-indicated rate). As the exercise tapers, this sensor-indicated rate returns to the programmed lower rate.

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Position V: Multisite Pacing With 2002 revision the, fifth column describes multisite pacing. Atrial multisite pacing might prevent atrial fibrillation. Ventricular multisite pacing is an acceptable means of pacing patients with dilated cardiomyopathy.

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modes of pacing 4 modes of pacing: - Asynchronous (AOO, VOO and DOO) Used safely in cases with NO ventricular activity. Disadvantages: Competes with patients intrinsic rhythm & results in induction of tachyarrythmias. Continuous pacing wastes energy & decreases battery half-life. - Single-chamber deman Atrial-only antibradycardia pacing. Inappropriate for chronic AF & long ventricular pauses.

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Single Chamber Ventricular Pacing (VVI, VVT) - Ventricular-only antibradycardia pacing. - Indicated complete heart block with chronic atrial flutter, AF & long ventricular pauses. Dual Chamber AV Sequential Pacing (DDD, DVI, DDI, VDD) - Preserve the normal atrioventricular contraction sequence. - Indicated AV block, carotid sinus syncope & sinus node disease. modes of pacing cont..

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PACEMAKER FAILURE Pacemaker failure has three aetiologies: 1) Failure to capture: ( the generator continues to fire but no myocardial depolarization takes place) a. Myocardial ischemia/infarction, b. Acid-base disturbance, c. Electrolyte abnormalities, d. Abnormal antiarrhythmic drug levels. e. External pacing might further inhibit pacemaker. 2) Lead failure, 3) Generator failure.

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Pacemaker syndrome occurs in patients with ventricular pacemakers. The awake patient may experience syncope, breathlessness, postural hypotension, and other symptoms associated with a low cardiac output. pacemaker is stimulating the venticles of the heart so, activation of the heart starts in the ventricles and then spreads upward to the atria. So, the normal activation of the heart electrically is reversed. the atria beat against closed valves.

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ICD (Implantable Cardioverter Defibrillator) Battery powered device to deliver sufficient energy to terminate VT / VF. all discharges are painful Superior to anti- arrhythmic therapy in preventing death in ventricular tachy- arrhythmias.

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Indications for ICDs A. Ventricular Tachycardia B. Ventricular Fibrillation C. Brugada Syndrome (RBBB, ST-segment elevation in V 1 to V 3 ) D. Arrhythmogenic RV Dysplasia E. Long Q-T Syndrome F. Hypertrophic cardiomyopathy G. Prophylactic use in patient who has cardiomyopathy with EF 35% & Post-MI patients with EF 30%.

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Generic Defibrillator Code NASPE/BPEG:

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Effect of Magnet Each PM/ICD is programmed to respond in a specific manner to magnet placement. Magnet usually result in pacemaker to switch to asynchronous mode. Magnet never turn off pacemaker. ICD will be inhibited to deliver antitachycardia therapy when magnet is applied. Pacemaker function of ICD is not inhibited.

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Effect of Magnet Magnet placement is not an advisable practice to employ in all cases. If the patient is not pacemaker dependent, an asynchronous mode will compete with the intrinsic rhythm. Some types of pacemakers, application of a magnetic field is a step required to initiate reprogramming of the generator. Random reprogramming when exposed to magnetic fields.

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Magnet application to a VVI pacemaker. Normal sinus rhythm with normal AV conduction Magnet application Fixed rate, ventricular pacing

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Anesthetic Considerations Preoperative Evaluation History; special attention for CV system, AMI, arrhythmia, underlying rhythm medical records review, review CXR, ECG Physical examination (check for scars, palpate for device). Direct interrogation with a programmer remains the only reliable method for evaluation; type, dependency on pacing, programmed function. Obtain manufacturers identification card. Get CXR if no other data available.

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Anesthetic Considerations Preoperative Evaluation cont.. Permenant pacemaker reprogramming: - Asynchronous pacing mode at a rate greater than the patients underlying rate ICD reprogramming: - Disabling the antitachycardia therapie function always indicated - With pacing function Disabling the anti- tachycardia therapy + Asynchronous pacing mode

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Single chamber pacemaker

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Dual chamber pacemaker

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Preoperative Preparation Determine whether EMI is likely to occur during the procedure. Determine whether reprogramming pacing function to asynchronous mode or disabling rate responsive function is advantageous or not Suspend antitachyarrhythmia functions if present. Anesthetic Considerations

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Preoperative Preparation cont Advise surgeon to consider use of a bipolar electrocautery or ultrasonic (harmonic) scalpel. Temporary pacing and defibrillation equipment should be immediately available. Evaluate the possible effects of anesthetic techniques and of procedure on PM function. Anesthetic Considerations

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Intraoperative Management Monitor operation of PM by: ECG. Monitor peripheral pulse (manual pulse palpation, pulse oximeter plethysmogram, arterial line). Because of the vasodilating effects of potent inhaled anesthetics, pacemaker syndrome in the anesthetized patient will be more significant than in the awake patient Preservation of intrinsic rhythm of the patient with a demand pacemaker is achieved by preventing bradycardia. Anesthetic Considerations

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Intraoperative Management cont.. beta agonists have potent inotropic, chronotropic and vasodilatory effects. This causes an increase in myocardial oxygen requirements and a decrease in systemic vascular resistance. Ischemia, myocardial infarction, or dysrhythmias may result. when suxamethonium is to be used in a patient with a permanent pacemaker, consideration should be given to reprogramming the pacemaker to asynchronous mode before induction of anaesthesia. Anesthetic Considerations

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Factors affecting pacing response decrease 1-4 weeks after implantation Myocardial ischaemia/infaction Hypothermia, hypothyroidism Hyperkalaemia, acidosis/alkalosis Antiarrythmics Severe hypoxia & hypoglycaemia. increase Increased catecholamines Stress, anxiety Sympathomimetic drugs Anticholinergics Glucocorticoides Hyperthyroidism Hypermetabolic status.

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Manage potential PM dysfunction due to EMI. 1. Electrocautery. Assure that electrosurgical receiving plate is positioned so that current pathway does not pass through PM. Advise surgeons to avoid proximity of cautery to PM or leads. Advise surgeons to use short, intermittent, and irregular bursts at the lowest feasible energy levels. Advise surgeons to reconsider use of bipolar electrocautery system. 2. Radiofrequency ablation. Advise surgeons to avoid direct contact between the ablation catheter and PM and leads. Advise surgeons to keep radiofrequency current path as far away from PM and leads.

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3. Lithotripsy. Advise surgeons to avoid focusing the lithotripsy beam near pulse generator. 4. MRI. MRI is generally contraindicated If MRI must be performed, consult with the ordering physician, cardiologist, radiologist and PM manufacturer.

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5. Radiation therapy. Radiation therapy can be safely performed. Surgically relocate the PM if the device will be in the field of radiation. 6. Electroconvulsive therapy. No significant damage if PM disabled Consult with the ordering physician, cardiologist, PM manufacturer.

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Postoperative Management Continuously monitor HR & rhythm. Have backup pacing & defibrillation equipment available throughout the immediate postoperative period. Interrogate and restore PM function in the immediate postoperative period. Restore all antitachyarrhythmic therapies in ICDs. Assure that all other settings of the PM are appropriate.

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References Practice Advisory for the Perioperative Management of Patients with Cardiac Rhythm Management Devices: Pacemakers and Implantable Cardioverter Defibrillators, ASA, Anesthesiology 103: 186198. T. V. Salukhe, D. Dob and R. Sutton, Pacemakers and defibrillators: anaesthetic implications, Br J Anaesth; 93: 95-104. ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities, J. Am. Coll. Cardiol.; 51; e1-e62 Kaplans Cardiac Anesthesia. Millers Anesthesia. Stoeltings Anesthesia & Co-existing Disease

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