9. Modern Pacemaker
Fully programmable dual chamber pacing
Rate response to activity and metabolic changes
Telemetry of pacer function
Incorporated algorithms to respond to change in
intrinsic rhythms
Store patients arrhythmic events
14. Pacing Lead
Unipolar
•
•
•
•
•
Bipolar
Large spike
More sensitive to interference
Pectoral muscle stimulation
More susceptible to EMI
Smaller lead diameter
• Small spike
• More sensitive to intrinsic
cardiac signals
• No myopotential inhibition
• EMI protected
• Less crosstalk
Anode
“+”
Unipolar
Anode
“+”
Cathod
“-”
Cathod
“-”
Bipolar
17. Myocardial and Epicardial Leads
Leads applied directly to the
heart
Fixation mechanisms include:
Epicardial stab-in
Myocardial screw-in
Suture-on
18. Fundamentals of Electricity
Ohm’s Law
6V
I=6/3=2A
U=IXR
U = Voltage (Volt, V)
I = Current (Ampere, A)
R = Resistance ( Ohm, Ω)
3Ω
12 V
6Ω
I = 12 / 6 = 2 A
21. How pacemaker works
Pacing : Amplitude (V), Pulse width (ms)
Pulse Amplitude (V)
Capture
Noncapture
Pulse Width (ms)
22. How Pacemaker Works
Sensing- Choosing sensitivity
Sensitivity
10.0 mV
Sensitivity
5.0 mV
Sensitivity 1.0 mV
23
23. Considerations in Sensitivity Programming
To make the device more sensitive (to pick up signals it
might be missing), lower the mV setting
To make the device less sensitive (to avoid detecting noncardiac signals), increase the mV setting
Sensitivity should
Pick up low-amplitude cardiac signals
Avoid very low-amplitude non-cardiac signals
24
24. NBG Code
I
II
III
IV
V
Chamber(s)
Paced
Chamber(s)
Sensed
Response to
Sensing
Rate
Modulation
Multisite
Pacing
O = None
A = Atrium
V = Ventricle
D = Dual (A +
O = None
A = Atrium
V = Ventricle
D = Dual (A +
O = None
T = Triggered
I = Inhibited
D = Dual (T +
O = None
R = Rate
O = None
A = Atrium
V = Ventricle
D = Dual (A +
V)
V)
modulation
I)
NASPE/BPEG Generic
NASPE is the North American Society of Pacing and Electrophysiology
BPEG is the British Pacing and Electrophysiology Group
V)
25. Mode Selection Considerations
Status of Atrial Rhythm
Intrinsic
Presence of Atrial
Tachyarrhythmias:
Acute/Chronic
Status of AV Conduction
Normal Slowed Blocked
Presence of Chronotropic
Incompetence
26
Single Chamber ?
Dual Chamber ?
Rate Modulation?
28. History of the AICD
Milestones
1969 - Dr. Mirowski and Dr. Morton Mower
begin collaborating and develop the first
experimental model
29. History of AICD Therapy
Milestones
1975 - The first device is implanted and tested in an
animal
1980 - The first patient is implanted with an AICD
device
34. Dual coil v.s. Single coil
Dual Coil
Single Coil
Advantange
Lower DFT
May easier to
remove
Disadvantage
Difficult to
remove
Higher DFT
35. ICD Modules
Electrogram and Data Storage
Special Functions
no sr eve R
i
y par e hT
not ac fi ssa C
i i
l
Measurements
gn s ne S
i
Induction
36. Therapy
High Voltage shock
Uses of High Voltage Therapy
To terminate:
Ventricular Tachycardia
Ventricular Fibrillation
Ph
ase
1
se
Pha
2
Thanks, I needed that!
39. Automatic Sensitivity Control (ASC)
Automatic Sensitivity Tracking
GAIN
From Sense/Pace
Leads
FILTER
Threshold adjusts
+ and - to adapt
to the signal
THRESHOLD
COMP
Sensed Event
40. Defib with slow VT and Fast VT
No therapy
Non-Treatment
SVT discrimination, VT
therapy deliver when VT
indicated
VF therapy
deliver
Treatment
Treatment
Treatment
Tach A
(Slow VT)
Tach B
(Fast VT)
(ATP and
CV Shocks)
(ATP and
CV Shocks)
500 ms
(120 bpm)
375 ms
(160 bpm)
Sinus
>500 ms
(<120 bpm)
Fib
(Shock)
300 ms
(200 bpm)
42. Ventricular Resynchronization with CRT
Pacing @ left lateral free wall in addition
to right side
Symmetric lateral and septal wall
conduction & contraction
More efficient pump
46
43. Optimal LV Lead Placement
Coronary Sinus
approach
Right Atrial
Lead
Left Lateral Free wall
LV Lead
Right Ventricular Lead
47
44. Venograms and LV Lead Placement
Anterior
Right
Lateral
Basal
Posterior
Align to CS
OS/ Middle
Vein
Mid
LAO
AP
Apical
RAO
1928: Mark Lidwell
Lidwell's device ran on alternating current and required a needle to be inserted into the patient's ventricle. In 1928 he used intermittent electrical stimulation of the heart to save the life of a child born in cardiac arrest
1932Hyman's device, described in 1932 (Fig.(Fig.40,40, ,41),41), was powered by a spring-wound hand-cranked motor and called by Hyman himself an “artificial pacemaker”, a term still in current use.
John Hopps (Fig. 48), an electrical engineer, was recruited on a part-time basis by the National Research Council of Canada and designed what was perhaps the first electronic device specifically built as a cardiac pacemaker. It was an external unit driven by vacuum tubes. The electrical impulses were transmitted via a bipolar catheter electrode to the atria using a transvenous approach. Atrial pacing was readily achieved and heart rate could be controlled with no uncomfortable chest wall contractions
Mr Larrson, 1915-2001, 25 replacement in his lifetimeThe first clinical implantation into a human of a fully implantable pacemaker was in 1958 at the Karolinska Institute in Solna, Sweden, using a pacemaker designed by Rune Elmqvist and surgeon Åke Senning, connected to electrodes attached to the myocardium of the heart by thoracotomy. The device failed after three hours. A second device was then implanted which lasted for two days. The world's first implantable pacemaker patient, Arne Larsson, went on to receive 26 different pacemakers during his lifetime. He died in 2001, at the age of 86, outliving the inventor as well as the surgeon.
EMI : electrical magnet interferrencecrosstalk means sensing the pacing of another chamber
Epicardial or myocardial leads are implanted to the outside of the heart. These implants represent less than 5% of leads implanted, and are used primarily in pediatric cases or for patients in whom transvenous lead implant is contraindicated.
The resulting signal, after filtering, will be compared to the programmed sensitivity. Any signal of less amplitude than the sensitivity level will be under sensed. This is again one way of avoiding over-sensing. A signal of good quality and amplitude will exceed the sensitivity level and thus be sensed.
The diagram points out how much of a balancing act it can be to program sensitivity. Let’s say the little signal indicated is a true cardiac signal that just happens to be small. You want the sensitivity “bar” low enough that such signals are detected. On the other hand, if that little signal was muscle noise or something else you did not want to detect, you would want sensitivity programmed high enough to not sense it.
This is why sensitivity must be programmed for each patient individually and evaluated (and possibly reprogrammed) at every follow-up session!
Guidant logo in upper right corner/
DF1-unipolar config
Frontier – LV for bottom
830V per maximum
In this configuration the device can deliver Tach A and B therapy (ATP and/or CV) and Fib therapy (HV Shocks).
Any rate less than 500 ms or 120 bpm will be called sinus and no therapy will be delivered.
Any rate above 500 ms or 120 bpm but less than 375 ms or 160 bpm will receive Tach A therapy.
Any rate greater than 375 ms or 160 bpm but less than 300 ms or 200 bpm will receive Tach B therapy.
Any rate greater than 300 ms or 200 bpm will receive Fib or shock therapy.
This configuration would be used rarely. The patient would have to have 2 different VT’s one fast and one slow.
An epicardial approach was used initially to attach a lead to the posterolateral wall of the LV via a thoracotomy. Although the transvenous approach is now used more widely because of reduced intraoperative complications and an easier postoperative recovery, the epicardial approach may still be considered when coronary access can not be achieved.
Notice sternal wires to confirm view
Notice LV and RV leads are in parallel
Notice sternal wires to confirm view
Notice LV and RV leads are in parallel
Notice LV and RV leads are as far apart as possible, separating Septal wall from LV free wall