Cardiovascular Safety Profile of Electrical Stun
Guns (TASER-X26): Effects of Cocaine
Intoxication on Induction of
Ventricular Fibrillation
Dhanunjaya Lakkireddy MD, Andrea Natale MD & Patrick Tchou MD

Presentation Title l May 22, 2009 l 1

Disclosure & funding information

• This study was funded by a research grant from
TASER International, Scottsdale, AZ. The funding
source had no role in the study design, performance
and data collection or analysis.

• None of the authors have any kind of conflict of interest
with TASER International.

Presentation Title l May 22, 2009 l 2

Background:
• Electrical stun guns, a.k.a neuromuscular incapacitation devices
(NMIDs), are increasingly used by law enforcement personnel
over traditional lethal and non-lethal weapons. From here
onwards we will use TASER synonymous to NMID.
• A frequently employed model (TASER X-26, TASER ®
International, Scottsdale, AZ) delivers high voltage-low current
electrical energy to the body, causing transient neuromuscular
disruption with incapacitation.
• The safety of these devices is under intense scrutiny with
several deaths being claimed to be related to its use.

Presentation Title l May 22, 2009 l 3

Background:

• Violent subjects who pose a threat to law enforcement
officers are often intoxicated from illicit drugs such as
cocaine, phencyclidine and amphetamines.

• Cocaine has a variety of cardiac effects including
potential proarrhythmic effects.

• Arrhythmogenic effects of TASER when applied to the
body surface at varying proximity to the heart and
orientations along the cardiac axis are not clearly
understood

• The interplay of cocaine and TASER current on the
induction of arrhythmias is not known.

Presentation Title l May 22, 2009 l 4

Objective:

• To determine vulnerability for VF induction by a
TASER at varying locations on the body surface
with and without cocaine

Presentation Title l May 22, 2009 l 5

Methods & Materials
• Animals: A total of 13 anesthetized adult pigs
• Stun gun: TASER® X26 is a 26-watt pistol-like device that
shoots two tethered darts and delivers up to 6000 volts
(typical output about 1500 volts) of peak electrical potential
at 19 rapid pulses per second over 5 seconds. Arcing
voltage (50,000 volts) is strictly “open-circuit”
• The average net current is < 2 mA (19 X 100μC) & Energy
per pulse is about 70 mJ with an output power < 1.5 W = 19
pps • 70 mJ.

Presentation Title l May 22, 2009 l 6

TASER-X26 and the modified current wave form
TASER X26 Current Waveforms

I~

2

t\ '"~

~

"'" "'"~
@

.,
I-

~

'~

-

1X

5X

------

~

10X

~

~

Current waveform characteristics at
x1, x5, x10 and x30 of the
standard discharge from TASER
X-26. Waveform of the standard
pulses has a duration of about
100 µs and a net delivered charge
of about 100 µC at standard
output. Variations of the current
waveform with increased output
are shown in this figure. Due to
effects of the transformers in the
output stages in front of the
capacitors, there is both an
increase in pulse duration and
peak current.
Presentation Title l May 22, 2009 l 7

Experimental protocol
VF vulnerability to application of
TASER current at multiples of
standard outputs @ 5 paireddart positions:
1. Sternal notch (SN) – point of
maximum cardiac impulse (PMI)
(Position-1),
2. SN – supra-umbilical region
(Position-2),
3. SN – infra-umbilical region
(Position-3),
4. side to side across the chest
(Position-4) &
5. upper to mid posterior region
(Position-5).

Front

Back

Cocaine infusion: In 5 pigs,high
dose cocaine was infused
intravenously at 8 mg/kg over 30
minutes. Plasma cocaine and
benzoylecognine levels 30 minutes
after infusion were 557±280 U/L and
462±123 U/L

Presentation Title l May 22, 2009 l 8

Results
Differences in VF vulnerability at the 5 tested positions
70

Output Multiples

60

Comparisons of the five positions
for MinVFIM and MaxSM
(p<0.001, Friedman test).
The symbols †, *, and + indicate
paired comparisons where
p > 0.05 by the Wilcoxon test. All
other paired comparisons had
p< 0.05.

*

*

+
+

50
40

†

30

†

20
10
0
P1

P2

P3

P4

P5

Positions
MinVFIM

VFT

MaxSM

Presentation Title l May 22, 2009 l 9

VF induction:
• At the standard strength of TASER current no fatal
ventricular arrhythmias were noted at any of the five tested
positions.
• However, at higher strengths of TASER current (approx. 4x)
Ventricular fibrillation could be induced at Position-1, while it
took up to 40X the TASER current to induce VF at position-5.
• This shows that the front of the body is more vulnerable for
VF induction than the back of the body at significantly higher
strengths of TASER current.
• The VF vulnerability decreased by at least 1.5 to 2 fold after
cocaine infusion.

Presentation Title l May 22, 2009 l 10

Differences in Maximum Safety Multiple (MaxSM), Maximum Ventricular
Fibrillation Induction Multiple (MinVFIM) and Ventricular Fibrillation Threshold
(VFT) at different positions before (B) and after (C) cocaine infusion.

Lo(

B-M:nSM

t-MuSM

p

B-MinVlIM

t-MinVTIM

P

B-VTI

t-VlT

P

PI

42±I.l0

8.6±6 .88

0.192

8.o±2.14

15 .o±lO.oo

0.135

6.l±1.92

113±2.19

o 2 tIl

P2

12.o±1.58

28.04.41

o ill 0

2O.o±1O .0

33.04.41

o ill 1

14st9.59

33.04.41

0.032

P3

22.o±8.31

50.0±l8.11

0.009

32.o±831

tIl .o±l8.11

0.009

21.o±s31

55.o±18.11

0.009

P4

30.o±1.01

48.o±11.89

0.010

4O.o±1.o1

58 .o±11.89

0.010

35.o±1.o1

53.o±11.&]

0.010

P5

38.04.41

60.o±14.l4

0.011

48.04.41

10 .o±14.l4

0.011

43.04.41

65.o±14.14

o.on

Presentation Title l May 22, 2009 l 11

Physiology behind our observations
• Na+ channel blocking + hypersympathetic = Arrhythmia (Cocaine)
• Cocaine + substrate = Arrhythmia (Substrate includes – myocardial
ischemia, infarct, metabolic abnormalities, artificial infusion of
catecholamines etc)
• Cocaine in the absence of an appropriate substrate may not be
arrhythmogenic and contrarily, may exert significant Na+ (class-Ia, Ib)
channel blocking effect like quinidine, procainamide, lidocaine,
disopyramide and mexiletine increasing VF thresholds
(Tisdale JE, Pharmacotherapy 1996 ; Inoue H, JACC1988; Wang RY, Am J Emerg Med 1999 ; Euler DE, J Cardiovasc Pharmacol 1988 )

Presentation Title l May 22, 2009 l 12

Limitations
• Findings may not apply to the diseased heart (potential substrate for
sustained ventricular tachycardia).
• Cocaine may interact differently in the presence of a substrate

• Presence of other substances of abuse could interact differently.

Presentation Title l May 22, 2009 l 13

Public health implications
• A standard 5-second stun gun application is unlikely to cause
life-threatening arrhythmias, at least in the normal heart
irrespective of the position of application.
• Avoidance of anterior chest as a target site would greatly
reduce any concern for induction of fatal ventricular
arrhythmias

Presentation Title l May 22, 2009 l 14

Conclusions
• Standard discharge from a TASER X-26 weapon did not
induce VF at any of the five tested locations and cocaine
increased the safety margin by 50-150% above the baseline
safety margin
• Applications away from the cardiac axis and cardiac apex
have higher VF safety margins than those close to it.

Presentation Title l May 22, 2009 l 15