IF you are a male 60 years and above, you may think having a recurrent pain in the tummy (abdomen) or back is nothing to worry about. While recurrent pain in the abdomen or back pain are common symptoms, they may warn of something more serious, as in the case of Mr A and Mr B. Both were in their 60s, had significant artery disease and had recurrent discomfort in their abdomen which was not due to run-of-the-mill conditions but a sinister condition called aortic aneurysm, which is the term for abnormal swelling of the large artery called the aorta.

Biggest artery

The aorta, the largest artery in the body, arises from the heart and makes a 180-degree turn downwards towards the lower part of the body where it divides into two main arteries, one to each leg. Along its course, it gives off branches which supply blood to all the organs in the entire body.

The diameter of the aorta decreases in a gradual manner from its origin in the heart to the lower part of the body. At the abdomen, the diameter of the aorta does not exceed 3cm in a normal person. The wall of the aorta has elastic tissue which allows it to expand slightly when blood is being pumped out of the heart. When the heart is resting to fill up its heart chambers with blood, the wall of the aorta "springs" back to its resting normal size (elastic recoil), and continues to push blood forward even when the heart is not pumping. This blood pressure generated by the aorta when the heart is resting (also called diastolic blood pressure or DBP) plays an important role in pushing blood through the heart arteries.

Swelling of the aorta

High blood pressure, diabetes mellitus, high cholesterol levels and smoking are risk factors which can weaken and stiffen the wall of the aorta. Less commonly, inherited conditions which cause decreased elastic tissue in walls of arteries, infection, or trauma can also damage the wall of the aorta. The most common segment of the aorta which gets damaged and weakened is the segment of the aorta in the abdomen below the origin of the kidney arteries. When the wall weakens, the diameter of the aorta widens. When the diameter of the aorta increases to 4cm or more, this bulging segment is called an aneurysm (derived from the Greek word meaning "to widen"). Generally, the aneurysm will progressively get larger and may eventually rupture. Rupture of an aneurysm is often life-threatening. In the US, rupture of an aneurysm accounts for about 2 per cent of all deaths in men over the age of 65 years.

Although aortic aneurysms occur more often in the abdominal aorta, it can also occur in the thoracic aorta. The incidence of ruptured thoracic aneurysms in individuals aged 60 to 69, 70 to 79 years and 80 to 89 years is about 10 per 1,000, 30 per 1,000, and 55 per 1,000 respectively. The prevalence of aortic aneurysms in the abdomen (abdominal aortic aneurysm or AAA) is about 5 per cent in men over 50 years of age.

In a study of aortic aneurysm patients considered unsuitable for surgery, of which post mortems were carried out in almost half the patients, the incidence of aneurysm rupture was estimated as about 8 per cent, 10 per cent, and 20 per cent per year for aneurysms of diameter 5.5 to 5.9, 6.0 to 6.9, and >7.0 cm, respectively. The above findings were published in the Journal of the American Medical Association in 2002.

Risk factors

If you are male, 60 years of age or more and have family members with aortic aneurysm, your risk of developing it is much higher. About 20 per cent of brothers of patients with AAA develop the condition.

Smoking is a significant risk factor. It increases the risk of developing AAA, increases AAA swelling, increases the risk of rupture and is associated with a worse prognosis. Studies show that current smokers can have a 15 to 20 per cent increase in the rate of expansion of the aneurysm and double the risk of rupture.

In the Oxford Vascular Study, male current smokers of 65 to 74 years have an approximate 3 per cent 10-year risk of acute AAA rupture. The study by Dominic published in the Journal of the American Heart Association in 2015 prospectively examined the population in Oxfordshire, in the UK, from 2002 to 2014 for AAA.

High cholesterol level is associated with a higher risk of AAA and hence, cholesterol reduction should be considered in patients.

The association between high blood pressure and AAA is less clear although intuitively, one would have considered that high blood pressure will increase the risk of AAA. This could be because patients with high blood pressure are treated with medication and the level of control of blood pressure may vary from patient to patient. In addition, the drugs used to treat high blood pressure may also affect the development of AAA.

Data from a study published in the Journal of Vascular Surgery in 2002 by Wilmink reported an association between aortic aneurysm and blood pressure only in patients receiving calcium channel blockers. Calcium channel blockers are the most potent of the high blood pressure medications and it may be possible that these patients were those with more severe high blood pressure.

A meta-analysis study published in the British Journal of Surgery in 2012 by Sweeting reported that high blood pressure increases the risk of aortic aneurysm rupture by 30 per cent per 10 mm Hg increase in mean blood pressure. This association is particularly seen in women and women with AAA have a four-fold increase in risk of AAA rupture as compared to men.

Less commonly, genetically inherited disorders which weaken the wall of arteries will predispose a person to aneurysm. These include Marfan's syndrome and Ehler-Danlos syndrome, conditions which are associated with hypermobile joints and increased flexibility of joints. Hence, if you have joints that can bend beyond the usual angulation and if your body habitus is tall and thin, you may have one of these conditions and must be mindful that you have a higher risk of developing an aortic aneurysm.

Aneurysm formation can be caused by bacterial infections (such as syphilis and staphylococcus aureus infection), inflammation of the arterial wall (such as giant cell arteritis, Behcet's disease and Kawasaki syndrome), consumption of harmful drugs (such as cocaine and amphetamines) and trauma. However, these causes are rare.

Screening

Currently the UK and the US Medicare programmes provide for AAA screening of men aged 65 years who have a history of smoking. You may need an ultrasound or computed tomography X-ray scanning of the aorta to look for aortic aneurysm if your risk of developing aneurysm is high. This includes the following situations:

Male smokers aged 65 years and above;

Mr A agreed to undergo stent graft insertion for his AAA and till today has remained well. Mr B, on the hand, kept on postponing the insertion of a stent graft. One day, when he was overseas, he developed abdominal pain and low blood pressure and was hospitalised. Sadly, the AAA ruptured and he did not make it.

Where AAA is concerned, early treatment is necessary once it reaches a critical size, otherwise the consequence will be deadly.