
Adaptiv Biphasic Defibrillation
Bi-Phasic vs. Mono-Phasic
Technical
LIFEPAK  Education. Copyright Medtronic Corporation, September 2002
Adaptiv Biphasic Defibrillation

 Definition:
 Termination of lethal heart rhythms by application of a
biphasic defibrillation shock
 Clinical Significance:
 The first major advance in defibrillation technology in 30
years
 Improved first shock efficacy as compared to “gold
standard” monophasic defibrillation
LIFEPAK  Education. Copyright Medtronic Corporation, September 2002
Adaptiv Biphasic Defibrillation Continued . . .

 A Brief History Of Defibrillation
 1950s and prior
• AC defibrillation: Low efficacy, high occurrence of myocardial
damage
 1960s
• Introduction of DC defibrillation: Most devices using a
damped sinusoidal defibrillation waveform (Monophasic,
Lown, Edmark)
• Great improvement in patient outcome; Monophasic DC
defibrillation becomes the standard of care
 1970s, 1980s
• Research continues, but NO IMPROVEMENTS IN THERAPY
 Late 1990s
• Introduction of 3D Biphasic defibrillation technology;
Improved first-shock efficacy, emergence of a new standard
of care
LIFEPAK  Education. Copyright Medtronic Corporation, September 2002
Adaptiv Biphasic Defibrillation Continued . . .

 Monophasic Defibrillation
 Characterized by:
• Unidirectional current flow
• High peak current (>50 amps @ 360 joules)
• Short pulse duration (3 – 10 ms)
Monophasic Defibrillation
C
U
R
R
E
N
T
I Peak
TIME
T10%
(3.1 - 9.2 m s)
LIFEPAK  Education. Copyright Medtronic Corporation, September 2002
Adaptiv Biphasic Defibrillation Continued . . .


 Adaptiv Biphasic Defibrillation
 BTE (Biphasic Truncated Exponential) waveform
 Characterized by:
• Bi-directional current flow
• Lower peak voltage (<2200V @ 360 joules) and current
• Fast rise and fall times
3D Biphasic Defibrillation
C
U
R
R
E
N
T
I1
T PHASE 2
4.5 - 5.3 ms
TIME
T PHASE 1
(6.8 - 7.9 ms)
I4
LIFEPAK  Education. Copyright Medtronic Corporation, September 2002
Adaptiv Biphasic Defibrillation Continued . . .

 Differences In Product Architecture

 The Adaptiv Biphasic defibrillator uses several
components not found in the monophasic model:
• Biphasic PCB assembly
• Energy storage capacitor
 Metalized polypropylene
 196 uF
• Inductive Resistor
• High voltage isolation relay
LIFEPAK  Education. Copyright Medtronic Corporation, September 2002
Adaptiv Biphasic Defibrillation Continued . . .

 How It Works:
 Review: Monophasic defibrillation
• The storage capacitor is charged
• The capacitor discharges through the waveshaping inductor
and the patient impedance in a single-phase pulse
Wav eshaping
Inductor
+ Energy
Energy Storage
Capacitor
Charger
Storage
Capacitor
C
u
r
r
e
n
t
Time
Monophasic
Defibrillator
Transfer
Relay
LIFEPAK  Education. Copyright Medtronic Corporation, September 2002
Adaptiv Biphasic Defibrillation Continued . . .

 Biphasic Defibrillation: The “H” Bridge
 The biphasic shock is delivered through a semiconductor
bridge
• Each element is assigned a map coordinate for identification
 Two different semiconductor components are used:
• SCRs (three in a custom package)
• A single Insulated Gate Bipolar Transistor (IGBT)
The "H" Bridge
Inductive
Resistor
NW
Energy
Storage
Capacitor
NE
Custom
SCR
Package
+
Bridge
Outputs
(To Paddles)
SW
SE
IGBT
LIFEPAK  Education. Copyright Medtronic Corporation, September 2002
Adaptiv Biphasic Defibrillation Continued . . .

 Characteristics Of The “H” Bridge Components
 The SCR
• With gate voltage applied,
the switch closes – current flows
from terminal to terminal
• As long as current is flowing,
• removing gate drive DOES NOT
open the switch
 The IGBT
• With gate voltage applied,
the switch closes – current flows
from terminal to terminal
• Removing gate drive opens the switch
Current
Flow
Gate
Driv e
Current
Flow
Gate
Driv e
LIFEPAK  Education. Copyright Medtronic Corporation, September 2002
Adaptiv Biphasic Defibrillation Continued . . .

 The Biphasic Shock - 1st Phase Begins
 NW and SE switches close
• Under control of the biphasic PCB processor
• Current flows for the 1st phase
Biphasic Discharge
Ind uctive
Resistor
NW
Energy
Sto rage
Cap acitor
NE
+
SW
SE
C
U
R
R
E
N
T
0V
TIME
LIFEPAK  Education. Copyright Medtronic Corporation, September 2002
Adaptiv Biphasic Defibrillation Continued . . .

 The Biphasic Shock – 1st Phase Ends
 SE switch is opened
• Interrupts current flow
• NW switch opens spontaneously when current flow stops
 Charge remains on storage capacitor
Biphasic Discharge
Ind uctive
Resistor
NW
Energy
Sto rage
Cap acitor
NE
+
SW
SE
C
U
R
R
E
N
T
0V
TIME
LIFEPAK  Education. Copyright Medtronic Corporation, September 2002
Adaptiv Biphasic Defibrillation Continued . . .

 The Biphasic Shock – Interphase Time
 All switches open for 500 uS
• Current flow settles to zero
Biphasic Discharge
Ind uctive
Resistor
NW
Energy
Sto rage
Cap acitor
NE
+
SW
SE
C
U
R
R
E
N
T
0V
TIME
LIFEPAK  Education. Copyright Medtronic Corporation, September 2002
Adaptiv Biphasic Defibrillation Continued . . .

 The Biphasic Shock – 2nd Phase Begins
 NE and SW switches close
• Current flows in the opposite direction
• 2nd phase is created
Biphasic Discharge
Ind uctive
Resistor
NW
Energy
Sto rage
Cap acitor
NE
+
SW
SE
C
U
R
R
E
N
T
0V
TIME
LIFEPAK  Education. Copyright Medtronic Corporation, September 2002
Adaptiv Biphasic Defibrillation Continued . . .

 The Biphasic Shock – 2nd Phase Ends
 All switches close
• Any remaining charge is shorted out through the A14
Inductive Resistor
Biphasic Discharge
Ind uctive
Resistor
NW
Energy
Sto rage
Cap acitor
NE
+
SW
SE
C
U
R
R
E
N
T
0V
TIME
LIFEPAK  Education. Copyright Medtronic Corporation, September 2002
Adaptiv Biphasic Defibrillation Continued . . .

 The Biphasic Shock – Energy Dump
 To dump unwanted energy, all switches close
• The A14 Inductive Resistor acts as the dump resistor
Indu ctive
Resistor
NW
Energy
Storage
Cap acitor
NE
+
SW
SE
LIFEPAK  Education. Copyright Medtronic Corporation, September 2002
Components

Continued . .
Inductive Resistor
 Less resistance and inductance than monophasic
waveshaping inductor
• 5 ohms, 700uH vs. 10.8 ohms, 21mH

Performs Several Critical Functions
 Limits current during shorted paddles discharge
 Limits current during internal dump (acts as dump
resistor)
 Truncates 2nd phase (absorbs remaining energy)
LIFEPAK  Education. Copyright Medtronic Corporation, September 2002
Adaptiv Biphasic Defibrillation Continued . . .

 Adaptive Defibrillation

 The Adaptiv Biphasic waveform adapts to the impedance
of the patient
• Optimizes the energy delivered
 Three variable parameters:
• Peak voltage
• Duration
• Tilt
 Adaptations are based on patient impedance measurement
LIFEPAK  Education. Copyright Medtronic Corporation, September 2002
Adaptiv Biphasic Defibrillation Continued . . .

Which waveform is right for you???
LIFEPAK  Education. Copyright Medtronic Corporation, September 2002
Adaptiv Biphasic Defibrillation Continued . . .

 Paddles Patient Impedance Measurement
 Based on voltage measurements taken during defibrillation
• 1st measurement - peak voltage of 1st phase
• 2nd measurement – after 4.5 ms
• Delta-V calculation; provides patient impedance
Impedance Measurement
V1
V2
4.5
mS
LIFEPAK  Education. Copyright Medtronic Corporation, September 2002
Adaptiv Biphasic Defibrillation Continued . . .

 Patient Impedance Measurement Continued . . .
 1st phase duration is adjustable
• As a function of measured patient impedance
• “Tilt” changes as a by-product of the duration adjustment
 Compensates the shock for the patient’s impedance
Impedance Measurement
1st Phase
Duration Adj usts
LIFEPAK  Education. Copyright Medtronic Corporation, September 2002
Adaptiv Biphasic Defibrillation Continued . . .

 Two Subsequent Measurements Are Taken
 End of 1st phase, end of 2nd phase
• 2nd phase duration always 2/3 of first phase
 Used to sense open or shorted discharge
• “Energy Fault” message is displayed
Impedance Measurement
V3
V4
LIFEPAK  Education. Copyright Medtronic Corporation, September 2002