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Moderator : Dr Manju Mani

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1 Moderator : Dr Manju Mani

2  First totally implantable pacemaker : into the chest of 43 yr old Arne Larsson by Dr Ake Senning in Stockholm on Oct 8,1958.  Introduction of external defibrillators in 1962  First internally implanted defibrillator in 1980

3 Device that provides electrical stimulation to cause cardiac contraction when intrinsic cardiac electrical activity is slow or absent

4 1. Stimulate cardiac depolarization 2. Sense intrinsic cardiac function 3. Respond to increased metabolic demand by providing rate responsive pacing

5 1. Aquired AV block AV block  Symptomatic bradycardia  Asystole >3 sec or escape rhythm <40bpm  Post op AV block not expected to resolve  Neuromuscular disease with AV block AV block  Permanent or intermittent symptomatic bradycardia

6 2. After MI  Symptomatic 2 0 AVB or 3 0 AVB  Infranodal AV block with LBBB 3. Bifascicular or Trifascicular block  intermittent complete heart block with symptoms  2 AV block  Bundle branch block

7 4. Sinus Node Dysfunction - with symptoms as a result of long term drug therapy - symptomatic chronotropic incompetence 5. Hypertensive carotid sinus & neurocardiac symptoms - recurrent syncope associated with carotid sinus stimulation - Asystole of > 3 sec duration in absense of any medication

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9  Pulse Generator  Electronic Circuitry  Lead System

10  Subcutaneous or submuscular  Lithium battery  4-10 years lifespan  long life and gradual decrease in power  sudden pulse generator failure is an unlikely cause of pacemaker malfunction

11  Sensing circuit  Timing circuit  Output circuit

12 Bipolar  Lead has both negative, (Cathode) distal and positive, (Anode) proximal electrodes  Separated by 1 cm  Larger diameter: more prone to fracture  Compatible with ICD Unipolar  Negative (Cathode) electrode in contact with heart  Positive (Anode) electrode: metal casing of pulse generator  Prone to oversensing  Not compatible with ICD

13  current travels only a short distance between electrodes  small pacing spike: <5mm Anode Cathode + -

14  current travels a longer distance between electrodes  larger pacing spike: >20mm Anode Cathode + -

15 VVI / 60

16 I Chamber Paced II Chamber Sensed III Response to Sensing IV Programmable Functions/Rate Modulation V Antitachy Function(s) V: Ventricle T: Triggered P: Simple programmable P: Pace A: Atrium I: Inhibited M: Multi- programmable S: Shock D: Dual (A+V) D: Dual (T+I) C: Communicating D: Dual (P+S) O: None R: Rate modulating O: None S: Single (A or V) O: None

17  VVI  Ventricular Pacing : Ventricular sensing; intrinsic QRS Inhibits pacer discharge  VVIR  As above + has biosensor to provide Rate- responsiveness  DDD  Paces + Senses both atrium + ventricle, intrinsic cardiac activity inhibits pacer d/c, no activity: trigger d/c  DDDR  As above but adds rate responsiveness to allow for exercise

18  When the need for oxygenated blood increases, the pacemaker ensures that the heart rate increases to provide additional cardiac output Adjusting Heart Rate to Activity Normal Heart Rate Rate Responsive Pacing Fixed-Rate Pacing Daily Activities

19  Wallet card: 5 letter code  CXR: code visible  Single lead in ventricle: VVI  Separate leads DDD or DVI

20  VVI - lead lies in right ventricle  Independent of atrial activity  Use in AV conduction disease

21  Typically in pts with nonfibrillating atria and intact AV conduction

22  Magnet application  No universal function of magnet  Model-specific magnet, some activate reed switch  asynchronous pacing at pre-set rate  Interrogation / Programming  Model-specific pacemaker programmer can non- invasively obtain data on function and reset parameters

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24  Venous access  Infection  Thrombophelbitis  Pacemaker Syndrome

25  Bleeding  Pneumo / haemothorax  Air embolism

26  2% for wound and ‘pocket’ infection  1% for bacteremia with sepsis  S. aureus and S. epidermidis Rx : If bacteremic: start antibiotics, remove system, new system to be placed

27  Incidence 30-50%  b/c of collateralization only % devp symptoms  Swelling, pain, venous engorgement  Rx Heparin, lifetime warfarin

28  Presents with worsening of original symp post-implant of single chamber pacer - hypotension, syncope,vertigo, exercise intolerance etc  AV asynchrony  retrograde VA conduction  atrial contraction against closed MV + TV  jugular venous distention + atrial dilation  sx of CHF  Rx : dual chamber pacer

29 Pacemaker syndrome

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31 1. Failure to Output 2. Failure to Capture 3. Inappropriate sensing: under or over 4. Inappropriate pacemaker rate

32 absence of pacemaker spikes despite indication to pace  dead battery  fracture of pacemaker lead  disconnection of lead from pulse generator unit  Oversensing  Cross-talk: atrial output sensed by vent lead

33 spikes not followed by a stimulus-induced complex  change in endocardium: ischemia, infarction, hyperkalemia, class III antiarrhythmics (amiodarone, bertylium)

34 Failure to sense or capture in VVI

35 Pacemaker incorrectly misses an intrinsic deoplarization  paces despite intrinsic activity  Appearance of pacemaker spikes occurring earlier than the programmed rate: “overpacing”  may or may not be followed by paced complex: depends on timing with respect to refractory period  AMI, progressive fibrosis, lead displacement, fracture, poor contact with endocardium

36  Pacemaker does not “see” the intrinsic beat, and therefore does not respond appropriately Intrinsic beat not sensed Scheduled pace delivered VVI / 60

37 Detection of electrical activity not of cardiac origin  inhibition of pacing activity  “underpacing”  pectoralis major: myopotentials oversensed  Electrocautery  MRI

38  An electrical signal other than the intended P or R wave is detected Marker channel shows intrinsic activity......though no activity is present VVI / 60

39  Rare reentrant tachycardia seen w/ dual chamber pacers  Premature atrial or vent contraction  sensed by atrial lead  triggers vent contraction  retrograde VA conduction  sensed by atrial lead  triggers vent contraction  etc etc etc  Tx: Magnet application: fixed rate, terminates tachyarrthymia,  reprogram to decrease atrial sensing

40  Circuitry or power source of pulse generator  Pacemaker leads  Interface between pacing electrode and myocardium  Environmental factors interfering with normal function

41  Loose connections  Similar to lead fracture  Intermittent failure to sense or pace  Migration  Dissects along pectoral fascial plane  Failure to pace  Twiddlers syndrome  Manipulation  lead dislodgement

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43  Dislodgement or fracture (anytime)  Incidence 2-3%  Failure to sense or pace  Diagnosed with CXR, lead impedance  Insulation breaks  Current leaks  failure to capture  Diagnosed with measuring lead impedance (low)

44  Early or late  Usually well tolerated  Asymptomatic  inc’d pacing threshold, hiccups  Diagnosis : hiccups, pericardial friction rub CXR, Echo

45 MRI Electrocautery Arc welding Lithotripsy Microwaves Mypotentials from muscle

46  Allows a lower rate between sensed events to occur; paced rate is higher Lower Rate 70 ppm Hysteresis Rate 50 ppm

47 47 MAC To provide comfort To control dysrhythmias To check for proper function/capture Have external pacer & Atropine ready Continuous ECG and peripheral pulse monitoring

48 48

49  Invasive (Direct) cardiac Pacing  Epicardial Stainless steel Teflon coated wires.  Endocardial Flow directed balloon electrodes Catheter with guidewire With PA catheter- Side port for ventricular pacing  Non Invasive (Indirect)  Transcutaneous Pacing Combined pacing, cardioversion and defibrillation with ECG monitoring in a single unit Instituted quickly Safely by minimally trained person

50  Disadvantages of transcutaneous pacing  Inability to obtain reliable capture in Emphysema Pneumothorax Morbid obesity  Difficulty with lead placement Surgical Field Patient position  Failure of TCP to preserve AV synchrony For patients with poor ventricular diastolic function

51  Uses  Noninvasive electrophysiological studies  Termination of reentrant tachydysrhythmias  Temporary bradycardia pacing  Disadvantages  Not suitable for ventricular pacing  Intact AV conduction is required

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53  Indications  Recurrent VT/VF  Not responding to medical therapy  Poor risk for surgical ablation  2/3 rd patients still require medical therapy  High cost  Survival rate is similar

54 54 Gives a shock at joules Usually 25 joules Takes 5-20 seconds to sense VT/VF Takes 5-15 seconds more to charge second delay before next shock is administered Total of 5 shocks, then pauses If patient is touched, may feel a buzz or tingle If CPR is needed, wear rubber gloves for insulation

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57 PG assembly cc 120 cc 80 cc 72 cc 54 cc 62 cc 49 cc 39.5 cc 36 cc 38 cc 39.5 cc Implantable Defibrillators ( )

58 PG assembly 2010

59 Position 1 Shock chambers Position 2 Anti tachycardia pacing chambers Position 3 Tachycardia detection Position 4 Anti bradycardia pacing chambers O = none E = electrocardiogram O = none A = atrium H = haemodynamic A = atrium V = VentricleV = ventricle D = dual (A+ V)

60  Non thoracotomy (More common)  Fluoroscopically Transvenous Monitored anesthesia care. General anesthesia- if repeated induction of arrhythmia.  Thoracotomy ( For Pediatric patients- epicardial leads)  Median sternotomy  Left thoracotomy  Subxiphoid approach  Subcostal approach

61 61 MAC vs General Usually general due to induction of VT/VF so AICD can be checked for performance Lead is placed in heart Generator is placed generally in upper chest

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63 A. Establish whether a patient has a cardiac rhythm management device (CIED). 1. Conduct a focused history (patient interview, medical records review, and review of available chest x-rays, electrocardiograms, or any available monitor or rhythm strip information). 2. Conduct a focused physical examination (check for scars and palpate for device).

64 3. Define the type of CIED. a. Obtain manufacturer’s identification card from patient or other source. b. Order chest x-ray if no other data are available.

65 B. Determine the dependence on pacing function of the CIED. 1. Patient has history of symptomatic bradyarrhythmia resulting in CIED implantation. 2. Patient has history of successful atrioventricular nodal ablation. 3. Patient has inadequate escape rhythm at lowest programmable pacing rate.

66 C. Determine CIED function. 1. Interrogate device (consultation with a cardiologist or pacemaker-ICD service may be necessary). 2. Determine whether the device will capture when it paces (i.e., produce a mechanical systole with a pacemaker impulse).

67 A. Determine whether EMI (electromagnetic interference) is likely to occur during the planned procedure. The pacemeker senses cautery signal as electrical activity, & may be inhibited causing asystole. In case of ICD, it may sense cautery as ventricular fibrillation and deliver a shock.

68 1. Determine whether reprogramming pacing function to asynchronous mode or disabling rate responsive function is advantageous. 2. Suspend antitachyarrhythmia functions if present. 3. consider use of a bipolar electrocautery system or ultrasonic (harmonic) scalpel. 4. Temporary pacing and defibrillation equipment should be immediately available

69 Monitor operation of the CIED. 1. Conduct electrocardiographic monitoring per ASA standard. 2. Monitor peripheral pulse (e.g., manual pulse palpation, pulse oximeter plethysmogram, and arterial line). 3. Pacemaker is not an indication for insertion of pulmonary artery & central venous catheter.

70  Narcotics & inhalational agents can be used successfully.  Succinylcholine fasciculations can inhibit stimulation and hence should be avoided.  Etomidate & ketamine should be avoided : cause myoclonic movements  Cases of pacemeker dislodgement by IPPV  Nitrous oxide entrapment in pacemeker pocket.

71 Factors that increase pacing threshold: - Acidosis / alkalosis - Hypothermia - Hyperkalemia - Hypoglycemia - Severe hypoxia - Hypothyroidism - Myocardial ischemia/ infarction

72 1.Assure that electrosurgical receiving plate is positioned so the current pathway does not pass through or near the CIED system. It placed on a site different from the thigh (e.g., the superior posterior aspect of the shoulder contralateral to the generator position for a head and neck case). 2. Avoid proximity of the cautery’s electrical field to the pulse generator or leads.

73 3. use short, intermittent and irregular bursts at the lowest feasible energy levels. 4. consider the use of a bipolar electrocautery system or ultrasonic (harmonic) scalpel in place of a monopolar electrocautery system if possible

74 1. Avoid direct contact between the ablation catheter and the pulse generator and leads. 2. keep the RF’s current path as far away from the pulse generator and lead system as possible.

75 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.

76 1. MRI is generally contraindicated in patients with CIEDs. 2. If an MRI must be performed, consult with the ordering physician, the patient’s cardiologist, the diagnostic radiologist, and the CIED manufacturer.

77 1. Radiation therapy can be safely performed in patients who have CIEDs. 2. Surgically relocate the CIED if the device will be in the field of radiation.

78 A. terminate all sources of EMI while the magnet is removed. b. Remove the magnet to reenable antitachycardia therapies. c. If the above activities fail to restore ICD function, proceed with emergency external defibrillation or cardioversion.

79 a. Position defibrillation/cardioversion pads or paddles as far as possible from the pulse generator. b. Position defibrillation/cardioversion pads or paddles perpendicular to the major axis of the CIED to the extent possible by placing them in an anterior-posterior location.

80 c. If it is technically impossible to place the pads or paddles in locations that help to protect the CIED, then defibrillate/cardiovert the patient in the quickest possible way and be prepared to provide pacing through other routes.

81 A. Continuously monitor cardiac rate and rhythm and have back-up pacing and defibrillation equipment immediately available throughout the immediate postoperative period.

82 B. Interrogate and restore CIED function in the immediate postoperative period. 1. Interrogate CIED; consultation with a cardiologist or pacemaker-ICD service may be necessary. 2. Restore all antitachyarrhythmic therapies in ICDs. 3. Assure that all other settings of the CIED are appropriate

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