Pacing Critical Care

1. Pacing & Critical Care

2. Introduction In anaesthesia and ICU ,deal with pacemakers, defibrillators in numerous clinical scenarios. Need to have working knowledge, and an approach to these patients Aims of this talk are to try and achieve this

3. Types of devices Pacemakers Permanent Temporary Transvenous Epicardial Transthoracic

4. Temporary Pacing 65 yr man post AVR with epicardial pacing wires. The ICU nurse comes to you �The pacemaker isn�t capturing,and seems to be undersensing in DDD. Can you fix it, or should I just stick it in VVI, or VOO at a backup, or put in a skin wire and reverse the polarities�.�

5. Temporary Pacing Electrodes Mode Sensitivity Output Troubleshooting

6. Electrodes Unipolar : one conducting wire and electrode. Electric current returns to pacemaker via tissue. Rarely used for temporary pacing as require skin wire for return current. Used for permanent

7. Electrodes Bipolar : 2 conducting wires surrounded by insulation. Current passes down one wire to an electrode, passes through tissue to cause depolarisation, returns to pacemaker via second electrode and wire. Method of choice for temporary pacing Can reverse electrodes If one limb fails, can convert to unipolar with skin electrode

8. Mode NASPE/BPEG Generic code 1st 3 positions refer to antibradycardic functions 4th,5th refer additional functions on implantable devices

9. Mode Position I - chamber paced (V,A,D) Position II - chamber sensed (V,A,D) Position III - response to sensing I (inhibition) - pacemaker discharge inhibited by sensed signal (AAI,VVI) T (trigger) - pacemaker discharges after sensed signal (VAT) D (dual)

10. Mode Position 4 - programmability P (programmability) : ability to externally change simple parameters ie rate, output M (multi) : more parameters C (communicating) : telemetry function R (rate-adaptive) : vary pacing rate by sensing biological parameters that reflect need for increased cardiac output. Include vibration, resp, Q-T, core temp, RV O2 sats, blood pH

11. Mode Position 5 - tachyarrhythmic functions P (pacing) : tachycardias S (shock) : deliver DC shock when sense tachycardia (usually VF,VT) D (dual) : both

12. Modes - Single Chamber AOO, VOO : asynchronous AAI : sense & pace atria inhibit if atrial activity greater than set rate. need functional atria to pace Need intact AV pathway

13. Modes - Single Chamber VVI - similar AAI but lose atrial synchrony Very safe fall back mode as not relying on AV conduction

14. Modes - Dual Chamber DDD both paced and sensed Atrial impulse - inhibit atrial output, trigger ventricular if no impulse in set PR interval Upper rate limits prevent ventricular pacing following excess atrial activity Common post cardiac surgery

15. Modes - Dual Chamber DVI (AV sequential) Both chambers paced Ventricle sensed & inhibited if AV conduction occurs Pacemaker rate must be set higher than atrial rate Can precipitate AF (asynchronous atrial) If sense atrial spike in ventricle asystole can occur (no demand in ventricle)

16. Terms Sensitivity : pacemaker senses electrical activity by potential difference between 2 electrodes. Testing involves turning output to 0 (prevent discharge) , setting rate below native rate, and reducing sensitivity (increase amplitude) until competition between paced and native occurs. Sensitivity is then set at half amplitude this occurs ie sensitivity increased.

17. Terms Pacing Threshold : current applied to heart. Defaults to 10 mA. Set rate at 10-15 bpm higher than native rate Check lowest output at which capture occurs Set 2-3 times higher

18. Temporary pacing 65 yr man post AVR with epicardial pacing wires. �The pacemaker isn�t capturing,and seems to be undersensing in DDD. Can you fix it, or should I just stick it in VVI at a backup, or put in a skin wire and reverse the polarities�.�

19. What to do? Undersensing : the pacemaker is not sensing underlying activity and pacing inappropriately Check native rate Reduce paced rate to below this Check sensitivity Consider reverse electrodes Consider change modes

20. What to do? Not capturing; Rate is 45, but not pacing Trying to pace - how can you tell? Not capturing Increase output Reverse polarity Skin electode Change mode

21. Temporary Pacing #2 Called to cardiac arrest in CCU to 67 yr man post inferior AMI in pulseless broad complex rhythm What is your management?

22. ACLS Guidelines

23. Temporary Pacing #2 You shock him Patient is clammy, cool periphery Rhythm strip shows�.

24. Rhythm strip

25. Management ACLS ABC Drugs Adrenaline Atropine CHB pharmacological atropine isoprenaline pacing transthoracic transvenous

26. Isoprenaline Synthetic catecholamine Predominantly chronotropic, ?1 effect Vasodilatory Net effect increase heart rate, BP stay the same or drop 1-50 mcg/min

27. Transthoracic pacing

28. Temporary transvenous pacing Sterile technique Seldinger insertion of pacing wire Fluoroscopic guidance optimal or balloon tipped catheter or atrial J wire, but easy to do without

29. Temporary transvenous pacing In emergent situation transvenous VVI with balloon tipped catheter Bipolar lead Should get ventricular ectopy then capture Set rate above native rate and test threshold Test sensing if safe

30. What are the complications CVL Insertion: needle injury to other structure, perforation, arrhythmia, embolism etc.. Maintenance:infection, perforation, thrombus etc Pacing related Undersensing, oversensing Failure capture Diaphragmatic pacing (common while in SVC, RV perforation)

31. Permanent Pacemaker 74 yr old having THR tomorrow morning. You see him 6:00 pm on ward, and he tells you he has PPM. What are the issues, how will you manage this?

32. Issues The patient The pacemaker The surgery

33. The Patient Why has he got a PPM Heart block Heart failure Heart transplant

34. Indications for PPM Class I (generally agreed) Symptomatic 2,3� block, SA node disease with syncope Class II (controversial but recognised) Asymptomatic CHB, resistant sinus bradycardia with minimal symptoms Class III (not indicated) 1� HB, asymptomatic sinus brady

35. Heart Failure & Pacing Theoretical benefits of pacing Optimal diastolic filling if prolonged PR interval, dual chamber pacing with short AV delay may be of benefit Short-term increases in CO up to 38% No long term studies

36. Heart Failure & Pacing Theoretical benefits of pacing Interventricular conduction 30-50% have defects Progress over time Make hemodynamically compromised verntricle worse with inco-ordinate conduction Biventricular pacing can improve synchrony and conduction

37. Heart Failure & Pacing Biventricular pacing In NYHA III,IV pts with prolonged QRS or LVED > 5.5cm, EF < 35% Prospective, randomised trials Improves quality of life indices, ex tolerance Reduces NYHA class, rehospitalisation LV paced by lead in distal branch coronary sinus

38. The Patient Is his heart OK? Very likely to have underlying heart disease History - ex tolerance, recent changes, etc Assess clinically Investigations - echo etc..

39. The Patient Other related issues Medications Antiarrhyhmics Antifailure agents Anticoagulants Antiplatelet agents

40. The Patient Other related issues Organ function Renal Diabetes Vascular

41. The Surgery Type of operation Interference Cardiac Output

42. Type of Operation Surgical field Does it include pacemaker/wires eg R mastectomy

43. Interference How will pacemaker respond to surgical millieu Diathermy Ventilation Muscle movement

44. Cardiac Output Is it going fast enough

45. Surgery What will you do to stop all these problems from happening?

46. The Pacemaker Find out more about it Type - antibrady, tachy, both When inserted When checked How will it respond to diathermy, OR, magnet Can settings be changed preop

47. The combination Usual anaesthetic appropriate for patients premorbid state Antibiotic prophylaxis Bipolar diathermy Tell surgeon not to cut or buzz things that might be important Have plan for malfunction Have phone number of technician

48. Implantable Defibrillator (AICD) You are down to give an anesthetic for the insertion of an AICD in cath lab tomorrow morning. What are the issues, how will you manage?

49. Issues Patient Heart disease Other co-morbidity Medications Procedure

50. Procedure Location Equipment Monitoring Positioning Operation - insertion, testing