ACE SHEAR (Harmonic Scalpel) – Need for Speed

ACE SHEAR (Harmonic Scalpel)
–
Need for Speed
Mr. Mahesh Patwardhan
Consultant Gynaecologist
Queen Elizabeth Hospital
Woolwich, London
Rationale for HARMONIC
technology in surgery
Cutting and coagulation can be
achieved with minimal tissue
damage and reduced risk
TECHNOLOGY
Electrical energy is passed to the handpiece
Piezo-electric ceramic disks in handpiece become excited
Disks transfer electrical energy into mechanical energy
Mechanical (longitudinal) motion is amplified at nodes in shaft
Reaches max. amplitude of 55,500 cycles/sec at blade tip
TISSUE EFFECT
Blade comes into contact w/tissue, pressure causes
coaptation of blood vessel
H+ bonds are broken, protein in cells is denatured
Denatured protein forms a sticky coagulum
This allows for simultaneous cutting and coagulation to
take place at a lower temperature than electrocautery
Cutting and hemostasis can be achieved with
minimal tissue damage and minimal risk
BALANCE OF TISSUE
EFFECTS
Cavitation
Cutting
Balance
Coaptation
Coagulation
CUT
n 
n 
The active blade vibrates
back and forth (50 - 100
µm) with 55.500 Hertz
The vibrating blade edge
cuts tissue by stretching it
beyond its elastic limit
CAVITATION
Motion of the blade creates an area of low pressure,
causing water to boil at a lower temperature.
vapor
at 37°C
tissue plane
energy
cavitation
Water vapor expands, causing the layers to separate which
enhances visualization of avascular plane of dissection.
COAPTATION
HARMONIC Blade
Blood Vessel
Ultrasound
Pressure
Coapted
Blood Vessel
COAGULATION
n 
n 
n 
Secondary heat from friction causes
protein denaturation (> 63° C)
Depends on exposure time (coupling
of tissue with ultrasonic energy)
In practice: fluent transition between
coaptation and coagulation
COAPTIVE COAGULATION
Vessel walls are collapsed/approximated due to pressure. The blade is
then activated...
…this causes the proteins within the cells to denature, forming a sticky
coagulum that coagulates the vessels.
ACTIVE SURGICAL
TEMPERATURES
Electrosurgery/Laser Surgery
HARMONIC
Protein
Coagulation
50º C
Proteins
disorganize
to form a
coagulum
Tissue
Dessication
100º C
150º C
Vaporization
of water
dessicates
tissues
Eschar
(oxidation)
400º C+
Eschar forms
when tissues
burn
LATERAL SPREAD OF
COAGUALTION
70
60
Lateral
spread
(cc²)
Electrosurgery
50
40
30
20
10
0
UltraCision
0
1
2
3
4
5
Time (sec)
Amaral JF, Chrostek CA. SAGES, 1995.
6
7
8
9
10
COMPARISON OF INCISION
Hepatic Tissue in Porcine Model
HARMONIC
Max Power = 35 Watts
Monopolar Pencil
50 watts Blend
5 FACTORS AFFECTING
CUTTING AND COAGULATION
! 
Power Level
! 
Tissue Tension
! 
Grip Force
! 
Blade Sharpness
! 
Time
POWER LEVEL
TISSUE TENSION
GRIP FORCE
Strong grip
Strong grip
Light grip
Light grip
BLADE SHARPNESS
Sharper
blade
•  Faster cutting
•  Less hemostasis
Blunt
surface
•  Slower cutting
•  More hemostasis
TIME
Less
time
More
time
•  Faster cutting
•  Less hemostasis
•  Slower cutting
•  More hemostasis
Raising the Standards
u 
u 
I want to decrease Operating
time
I want reliable vessel sealing
«  “I
«  I
want to sleep at night”
want no leakers at the seal
«  I
want minimal surrounding
thermal damage
u 
u 
I want to easily rotate the
instrument 360 degrees and be
a one handed instrument
I would like hand activation
HARMONIC ACE
Convex Surface
Blunt Nose
Concave Surface
Knife-Down
FEATURES
SEALS VESSELS UP TO 5mm IN DIAMETER
HALVES THE TRANSECTION TIME
GRASPING FORCE INCREASED BY 2 TIMES
SEAL STRENGTH IN EXCESS OF 2 TIMES SYSTOLIC PRESSURE
OPTIMAL OCCLUSION PRESSURE
AUDIBLE FEEDBACK “CLICK”
ALL PRODUCTS INCLUDE HAND ACTIVATION
HARMONIC ACE
INVENTIONS
n 
n 
Finger actuation vs.
Thumb actuation
eliminates “numb
thumb”.
7
Hand activation
buttons aligned to
prevent inadvertent
activation.
8
9
1
Pressure Profile
2
Pad Material
3
4
Force limiting
Spring Mech.
5
Improved end
effector
6
Click
7
Thumb
activation
8
9
1
0
1
1
1
2
Ergo handle,
Trigger, &
Mechanism
Pad Life
Clamp Force
SEALS VESSELS 66%
LARGER
*IN ANIMAL MODEL
*
SURGICAL STEPS
GENERATOR GEN04
Ready
Indicator
Increase
Standby Power
Level
Graphic
Display
Test
HandActivation
Capability
Alarm
Indicator
Power switch
Volume
Decrease
UserPower
Settable
Level
Minimum
Power
Setting
Maximum
Power
Level
Hand Piece
Receptacle
Has ACE really changed my
practice?
…
any questions?
Thank you