ANGIOGRAPHY
If your doctor suspects that something is awry, he may trot you off for angiography, an x-ray test supposed to examine the state of your arteries via a contrast dye. The doctor will place a catheter into a blood vessel in your arm or leg, guide it towards the heart, and inject what is usually an iodinated dye like isosorbide dinitrate, which then travels into the main pump of the heart. Once all this is in place, the doctor will then snap pictures of your heart from different angles, all the while replenishing the supply of dye.
There’s plenty of evidence that this test also has a poor batting average, wrongfully setting in motion one of a number of potentially lethal heart operations. In one test in Boston, half of the 171 patients recommended to have a coronary angioplasty (the operation where furred-up veins are opened by tiny inflated balloons) on the basis of their angiograph were found not to need the operation. In the end, only 4 per cent of the patients advised to have the angiograph really needed one.33
Angiographs are also especially open to misinterpretation. In another study in which the pathology reports of deceased patients were compared with prior angiographs, two-thirds were found to be wrong.34 A number of critics blame the test itself, which only examines the main coronary arteries, will not show any vessel smaller than a 0.5 mm in diameter and will only highlight, at best, a quarter of all the blood flowing to the heart.
Many patients with an abnormal angiogram are referred for surgery, when, at best, the procedure can locate the site of a block and its severity, but not overall heart function. Angiography, for instance, cannot distinguish between patients with stable and unstable angina.
There’s also a problem with accuracy. In one instance, after the deaths of three patients unsuccessfully treated by angioplasty, pathology reports found that the angiography on which the procedure was recommended had given misleading information about the patients’ conditions.35
Finally, this nasty little test is not without its own dangers. The procedure itself causes death in two of every 1,000 patients or, at very least, can trigger a heart attack, stroke or severe blood loss.
Serious side-effects occur, regardless of the type of dye used,36 and reactions to the dye often appear up to a week later. In one study, nearly half the patients involved complained of delayed reactions – including itchiness, rash and nausea – from one hour to seven days later.37 More than 5 per cent of patients suffer reactions to the dye of moderate intensity, particularly those who have had the test before,38 and one in ten will have a reaction of some sort. Although most are mild, at least 1 in every 2,500 is quite severe.39
If you have to have such a test, the less dangerous option may be magnetic-resonance-imaging angiography, which doesn’t require either x-rays or dyes, but a magnetic field and pulses of radiowave energy to produce pictures of soft body tissues.40 And as it provides pictures in three dimensions and on multiple planes, it shows better differentiation of tissues.
X-RAYS
X-rays are the most common procedure you’re likely to be exposed to at least once in your lifetime. Today they represent approximately 10 per cent of any Western nation’s health expenditure. Ionizing radiation is actually comprised of very high-frequency waves, which pass through living tissue. Depending on how dense the tissues are, the body retains some of this radiation. These absorbed rays are what gets recorded on the film as white or grey; those that pass completely through hit a plate of photographic film and show up as dark grey or black. Besides mammograms, bone x-rays and dental x-rays, the newest kind of x-rays include CAT scans, in which a moving beam of x-rays creates a three-dimensional picture, usually of the brain, and fluoroscopy, which sends the x-ray shadow picture onto a television screen. Occasionally contrast dyes like iopamidol or mediums like barium are used to provide a clearer picture.
Although the newest equipment uses lower and more precisely targeted doses, there is still no such thing as a safe x-ray (that goes for dental x-rays, too). In all of medicine there is virtually no disagreement that ionizing radiation is damaging – and those risks are multiplying as our understanding of the medium grows. ‘Medical irradiation is by far the largest man-made contribution to the radiation burden of the population of developed countries,’ R. Wootton, professor and director of Medical Physics at Hammersmith Hospital in London, wrote in a textbook on the subject. In the UK, he says, x-rays ordered by doctors account for over 90 per cent of the total radiation exposure of our population.41
X-rays harm people in three ways. First, they can damage individual cells (although the harm caused by the lower doses is usually quickly repaired). Rarely (but depending on exposure), this damage can convert the cell to a cancer cell. Although we don’t know exactly how this works, it has been proposed that, since a cell is 75 per cent water, most of the radiation will be absorbed by the water, forming free radicals, which are known to be carcinogenic.42
Second, if a woman is pregnant, it can injure the developing foetus, causing death or malformations.
Finally, x-rays can damage the sperm or ovaries of children or adults, causing abnormalities in future generations. We also know that x-ray exposure is cumulative; the danger of something going wrong may increase every time you get another one.
We’re still coming to grips with exactly how dangerous x-rays are, however. Unnecessary radiation from x-rays may be responsible for 700 cancer deaths in the UK every year, and perhaps 5,700 cancer deaths per year in the US, according to a recent Oxford University study.43 But these figures may still be conservative. A UK National Academy of Science committee reviewed the usual assumptions that x-rays were responsible for 1 per cent of all leukaemias and 1 to 2 per cent of all other cancers, and concluded that the real risk could be as much as four times higher44 – a conclusion also reached that same year by the International Commission on Radiological Protection.45 Recently, multiple x-rays have even been linked with multiple myeloma – a form of bone cancer now sharply on the rise. Those who’d had the most exposure had a four times increased risk, the National Cancer Institute found.46
As far back as the 1950s, medicine discovered a link between leukaemia and prenatal x-rays. X-raying pregnant woman used to be routine, on the ludicrous notion that x-rays could tell a doctor whether her pelvis was ‘wide enough’ for the foetus to fit through during birth. We now know that if children are exposed to x-rays in utero their risk of all cancers is increased by 40 per cent, of leukaemias by 70 per cent, and of tumours of the nervous system by 50 per cent.47 There also may not be a safe ‘dose threshold’; single babies who’d received five to six times less radiation than twins who’d been x-rayed more frequently had the same incidence of cancer.48 To put these numbers in perspective, for every million babies exposed in the womb to even a single rad of x-rays