Aneurysm: Screening Me Oftly

18. April 2013

Randomness often decides whether aneurysms are noticed in time. Screening programs in a number of countries show that taking a routine snapshot of  the main artery pays off. The search for biological time bombs in Germany could soon become a health insurance matter.

The case involving a prominent and well known presenter and sports journalist, Monica Lierhaus, ensured that the term aneurysm obtained meaning for the average man on the German street. During a medical intervention procedure in which the elimination of a small aneurysm of the cerebral artery was the plan, there were complications, whereupon Lierhaus was placed in an artificial coma, which lasted four months. More than a million people in Germany have a marked weakness in their vascular system. Most know nothing of the mortal danger of that weakspot which relates in particular to two main regions of the body. Aside from the high probability of dying from a rupture, patients with cerebral and aortic aneurysms have little in common.

Rupture is usually fatal

Outgrowths along the brain arteries, which show up in a skull x-ray, are mostly accidental findings. This is currently the situation with aortic aneurysms as well. But that, according to the aspirations of vascular surgeons in Germany, should change. Those such as Hans Henning Eckstein from TU Munich have for years been fighting for regular ultrasound screening of the main aortic artery. “Several large and well-done studies clearly show that where screening is done, fewer aneurysms end up popping.”

Using sections epidemiologists conclude that there is a frequency of aneurysms of large vessels of about two to three per cent. Men strongly represent the majority of carriers. Dissimilarly to those of the brain, they are affected about five times as often as women. Such a rupture is not survived by four out of five patients. However if a physician detects the advanced vascular damage in time, repair using a catheter under certain conditions may prevent the rupture without need for open surgery (DocCheck in 2010 reported in a video post on “EVAR” = endovascular aneurysm repair). It is more expensive in comparison, but in terms of perioperative mortality it is safer: the figures are about 5 per cent for open surgery, compared with 2 per cent for endovascular repair.

Screening: mortality reduction of 40 per cent

At least one aortic screening is done for men at retirement age at present in the U.S., the UK, Italy, Sweden and Australia. Important studies from the United States and especially from England are trying to establish whether viewing the ultrasound of the aorta really does deliver. Already in 1997 in England the UK Multicentre Aneurysm Screening Study (MASS) had begun. It now has, with 13 years of follow-on observation, been evaluated one last time and published in the British Journal of Surgery. The researchers then put the main artery of approximately 27,000 men aged between 65 and 74 under the microscope and compared the fate of these subjects with an equally large control group made up of those who received no invitation to a screening.

Aneurysms of more than three centimetres in size were examined regularly and operated when required. While in the screening group 224 patients died of a ruptured aneurysm, the equivalent number was 381 in the control group; the risk was therefore reduced by over 40 per cent. MASS is, simply due to the high number of participants and its long follow-up observation period, the most important study of aneurysm screening worldwide. Because this is only a one-time screening, in instances of negative finding death rates rise about eight years later due to recurrence of new aneurysms. Nevertheless prevention is, according to the calculations made by the British Health Service (NHS), effective. For each life year gained for the entire population through a campaign like this a cost of about 23,000 Euro is expected. The cost of the aortic ultrasound sits at around 8,700 Euro.

OP recommendation at five centimetres or more

For men an aneurism of about 5.5 cm size surgery means necessary. At that point the risk of rupture is higher than the death rate for the surgical procedure. If the doctor finds an aneurysm of a smaller size, for the patient this means waiting at first and maintaining regular checkups. All the more often if the size is increasing, because massive aneurysms grow faster, as a very recent meta-study in JAMA recently described. For a three-centimetre pistule a three-year interval is usually enough, with five centimetres there should however only be an interval of a few months. With women, according to the authors of the paper, there is on the other hand need for further research in order to be able to make recommendations on screening and follow-ups. For problem cases other rules apply. In smokers the protuberance grows faster, irregularly shaped aneurysms rupture more easily even at a small size.

Cerebral aneurysm: One in a hundred bursts every year

With brain aneurysms the ratios and measures are different and the risks of not discovering them in time are not yet exactly known. A Japanese study from last year examined 6700 unruptured aneurysms and arrived at an average risk of rupture of 0.95 per cent per year. In comparison to those three to four millimetres in size, those of one to two and a half centimetres have a nine times higher risk; with those of more than 2.5 centimetres the risk is increased 70-fold. Even though the survival rate of subarachnoid bleeding has in recent years risen by two-thirds, about half of the survivors nonetheless carry cognitive damage from the arterial tear.
A genetic component contributes to the formation of an aneurysm. Thus, the risk of this vascular weakness is increased fivefold when a relative (first degree) is also affected. Against this background, many experts recommend a control-check. The German Society of Neuroradiology (DGNR) has, however, opposed a mass screening program for cerebral aneurysms. Because the sense of having to live with a “time bomb” in the skull is for many patients just too unbearable. Just as it is within the thorax however the risk of surgery on small swellings is higher than the risk of an unexpected arterial tear.

Software for automated aneurysm detection

The psychological “time bomb” factor plays a role in the arguments for and against a screening program of aortic aneurysms. Therefore many research programs focus on the development process of aneurysms and on markers for their progressing growth. Involving about 60,000 Euro, a project taking place in Freiburg on “biomarkers for wall shear stress and tension” is being promoted. A Chinese research group recently described the role of Cathepsin S in the formation of aneurysms. Knock-out mice designed for this research (with an Apolipoprotein E mutation) developed significantly fewer breaks in the aortic wall. There are promising development approaches in the detection of this damage as well.

At the University of Magdeburg computer scientists and neuroradiologists have most recently joined forces and programmed software that recognises a cerebral aneurysm in MR and CT images and indicates it to the doctor. Since almost all brain aneurysms are still detected as chance findings, this monitoring program could lead to better screening.

Ultrasound Screen: five minutes for a human life

In order to prevent death due to aortic aneurysm over the next 13 years, public health authorities have had to invite 216 men aged between 60 and 65 for screening. Thus, the rate is far below that of other prevention programs. With mammography screening the figure is over 400. Nevertheless, until the present moment very little has been done except for a few starting attempts in getting what is probably quite an effective measure running, one which would also not overly burden the physician: “A whole five minutes for a simple check of the abdominal aorta by means of ultrasound could save the lives of these people”, says Hans Henning Eckstein.

In the foreseeable future however something may happen in health policy in this area. Aside from the applications to Germany’s Federal Joint Committee (G-BA), HTA (HealthTechnolgy Assessment) reports on the costs and benefits of routine checks are currently being created. A decision is due to be made in this area by the G-BA later this year. Defusing many of these vascular explosives would then at least be something within reach.

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