500 likes | 1.14k Views
Introduction . In anaesthesia and ICU ,deal with pacemakers, defibrillators in numerous clinical scenarios.Need to have working knowledge, and an approach to these patientsAims of this talk are to try and achieve this. Types of devices. PacemakersPermanentTemporaryTransvenousEpicardialTransth
E N D
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)
1ş 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