Mr. Chair, members, I thank you for your invitation.
I am a biomedical engineer. A biomedical engineer develops new tools to diagnose and treat illnesses. I have developed computer models that calculate how the current passes through the human torso, in order to improve electrocardiogram diagnoses. I have also developed systems for cardiac activation mapping to guide arrhythmia surgery.
[Editor's note: audiovisual presentation]
On the screen, you can see the surgeon applying a net with hundreds of electrodes to the surface of the heart. The signals from the net are analyzed by the computer, which gives an image of the electrical activation sequence of the heart during an arrhythmia, in order to identify the origin of the abnormal arrhythmia. So we could say that my expertise is in the fields of bioelectricity and cardiac arrhythmias.
Let us try to understand what happens when an electrical current is applied with a taser. First, a hundred 50,000-volt impulses are released. This current, which circulates through the body regardless of where the dart lands, is enough to stimulate the muscles and nerve endings. A warning signal is immediately sent to the autonomic nervous system. In turn, the autonomic nervous system mobilizes different organs. It sends signals to the heart telling it to beat more quickly. The heart rate will accelerate. It will go from 72 beats per minute at rest to between 137 and 140 beats per minute. This happens in every case.
When the electrodes get close to the heart, part of the current can stimulate one section of the heart. The stimulation in this section can spread to the rest of the heart, and the impulse current will cause an accelerated heartbeat. This is referred to as capture. This phenomenon has been well-documented in experiments on pigs and on humans wearing implantable pacemakers. Later on I will speak more about capture, that is, the way a taser impulse can cause the heart to contract.
There is a third possibility, which Dr. Hall mentioned earlier. If the electrodes are even closer to the heart and there is a sufficient current density, the current can stimulate several sections of the heart. These different sections of the heart will desynchronize and each contract based on their own rhythms. Instead of an organized, rapid contraction, it becomes anarchy, an electrical storm in the heart. This is referred to as ventricular fibrillation. Since the heart stops pumping blood efficiently, it leads to death.
However, everyone agrees that this phenomenon is very unlikely, because the current required to cause fibrillation is around 50 milliamps, but the current released by the taser is around two milliamps. But scientific literature shows that a group of researchers in Toronto reported a case in which, by using a taser to apply a current, fibrillation was directly induced in a pig.
That is a summary of the immediate effects of the taser. We are concerned with the deaths caused by taser shocks. A study by Dr. Strote and Dr. Range Hutson from the University of Washington provides more information about the nature of these deaths. The study covered the period from 2001 to 2004, during which it found that in the United States, there were 75 deaths that occurred less than 24 hours after the individual was shocked by a taser. The study did not include the other deaths for which an immediate cause of death could be determined.
Working with these cases, they spoke with the pathologists and were able to obtain 37 autopsy reports. The reports revealed that 54% of the deceased suffered from illnesses affecting the coronary arteries, which irrigate the heart, or from cardiomyopathy, which is a deterioration of the heart muscle. So, more than half of these people were suffering from heart diseases. In 78% of the cases, the individuals had consumed illegal substances, stimulants; in 76% of the cases, there was a diagnosis of excited delirium; in 27% of the cases, the doctors determined that the taser was a potential cause of death or a contributory cause of death.
However, that last point is debatable. I will focus on the presence of heart diseases in more than half of the cases. Why? Because it is possible to determine heart disease in an autopsy. It is possible to see a deterioration of the muscle. It is important to contrast the 54% with the prevalence of heart disease. In this case, we are talking about heart disease in the United States, where the prevalence is 8% of the general population. In men under the age of 45, the prevalence is much lower, between 2% and 4%.
In examining these figures, a statistician would note that if the taser did not in any way cause death, meaning that there was no association between the taser and death, the study sample should have the same proportion of heart diseases as the general population, which is 4% to 8%. But this is not the case. So a statistical association is being made, which is not enough to establish a cause-and-effect relationship.
To go further, we must examine the mechanisms involved. We can make an analogy between the taser and the programmed stimulation protocol that cardiologists use in diagnoses. If a patient presents with palpitation or syncope symptoms, the cardiologist will insert a catheter into the heart, through which a series of electrical impulses are emitted. Each impulse will cause the ventricles to contract. In the electrocardiogram, the left side indicates the normal rhythm. The red arrows represent the electrical impulses emitted by the catheter. We can also see the heart's response. The doctor follows about ten of these impulses with one or several premature impulses. Then the stimulation is stopped.
There are two possible outcomes. In the first case, the heart rate returns to normal—and that is what happens with normal subjects—and the cardiologist can reassure the patient. In the second case, one of the possibilities is that there could be ventricular tachycardia. The heart rate accelerates, reaches more than 100 beats per minute and continues. It is important to note that ventricular tachycardia happens only in cases where there is an arrhythmia substrate, for example, in the presence of an old myocardial infarction. In this case, part of the heart muscle has been replaced by a layer of scar tissue. The ventricular tachycardia may continue for a few seconds or even a few minutes. After a few minutes, the heartbeat may return to normal, or ventricular fibrillation may occur.
During a cardiological exam, the cardiologist has access to a defibrillator and can shock the patient to bring the heart rate back to normal. I think we can make an analogy between the series of impulses used by cardiologists to provoke arrhythmias and the series of impulses an individual receives from a taser.
In conclusion, I think that there is a clear statistical association between death after taser shock and heart diseases, and that there is a plausible explanation for how this device can lead to death. There could be a ventricular tachycardia which deteriorates into fibrillation after a few seconds or minutes. That could explain the cases when an individual dies a few minutes after a taser shock. There are other possible explanations. In some cases, there could be a ruptured aneurysm caused by increased blood pressure because of an increased heart rate, as we discussed earlier; there could be an electrolyte imbalance, and thus an imbalance in the concentration of ions, caused by the stimulation of the nervous system. So there are many avenues of investigation for research.
Heart diseases increase the probability of death after taser shocks, and the studies on healthy subjects are really insufficient to conclude that the taser is completely safe. We can study hundreds or thousands of volunteer 25-year-old police officers, who are athletic and in good health, but it does not mean a thing because in the general population there are people with all kinds of medical problems.
I was surprised to see in the warnings issued by TASER International to its clients—to the people purchasing tasers—a rather long paragraph which states:
...it is important to remember that the very nature of use of force and physical incapacitation involves a degree of risk that someone will get hurt or may even be killed due to physical exertion, unforeseen circumstances and individual susceptibilities.
Thus, there could be deaths in cases of predisposition to cardiac arrhythmia. This contradicts the statements made by the president of the company, who publicly said that this device did not pose any risks. The company's lawyers acknowledge that there is a risk.
I am not sure if it is my place to make recommendations, but I think that because of the real risk of death, if we use the taser, we must take precautions and limit its use to aggressive and dangerous subjects. Or, it should be used as a last resort. Police training should focus on the possibility of death. We must stop saying that this device does not pose a risk. I do not believe that is true. We must publish detailed incident reports to facilitate research. I agree on this with my colleague, Dr. Hall, who is trying to develop databases. It is very difficult to obtain information.
I think that the taser should be defined as an electrical weapon. We must stop calling it an impulse device, which means nothing. A television remote control is an impulse device. I think that term trivializes this object. It is a weapon.
Thank you.