SMART BIPHASIC WAVEFORM
Defibrillation is the only effective treatment for ventricular fibrillation, the
most common cause of sudden cardiac arrest (SCA). The defibrillation
waveform used by a defibrillator determines how energy is delivered to a
patient and defines the relationship between the voltage, current, and patient
impedance over time. The defibrillator waveform used is critical for
defibrillation efficacy and patient outcome.
A BRIEF HISTORY OF DEFIBRILLATION
The concept of electrical
defibrillation was introduced
over a century ago. Early
used 60 cycle alternating
current (AC) household
power with step-up
transformers to increase the
voltage. The shock was
delivered directly to the
heart muscle. Transthoracic
alternating current (AC) waveform
(through the chest wall)
defibrillation was first used in
The desire for portability led to the development of battery-powered direct
current (DC) defibrillators in the 1950s. At that time it was also discovered
that DC shocks were more effective than AC shocks. The first "portable"
defibrillator was developed at Johns Hopkins University. It used a biphasic
waveform to deliver 100 joules (J) over 14 milliseconds. The unit weighed 50
pounds with accessories (at a time when standard defibrillators typically
weighed more than 250 pounds) and was briefly commercialized for use in
the electric utility industry.
Defibrillation therapy gradually gained acceptance over the next two decades.
An automated external defibrillator (AED) was introduced in the mid-1970s,
shortly before the first automatic internal cardioverter-defibrillator (AICD)
was implanted in a human.
Historically, defibrillators used one of two types of monophasic waveforms:
monophasic damped sine (MDS) or monophasic truncated exponential
(MTE). With monophasic waveforms, the heart receives a single burst of
electrical current that travels from one pad or paddle to the other.
HEARTSTART FR3 DEFIBRILLATOR TECHNICAL REFERENCE MANUAL