The aorta is the largest artery in the body – your personal equivalent of Highway 401 (a motorway that is 18 lanes wide in parts). Because the aorta is so large, it is subjected to high pressures, which can cause it to weaken and dilate. This can lead to a complication of high blood pressure known as aortic aneurysm. If an aortic aneurysm ruptures, a catastrophic loss of blood can occur.
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The aorta leads away from the left ventricle of the heart, and is subjected to immense pressure as blood surges through with each heartbeat. This makes the lining of the aorta a hotspot for hardening and furring up (atherosclerosis) especially if you have poorly controlled hypertension, a raised cholesterol, poorly controlled diabetes or smoke cigarettes.
If your blood pressure is continually in the hypertensive range, the aorta can dilate to form a weakened bulge known as an aortic aneurysm.
A dilation that occur in the chest is known as a thoracic aortic aneurysm.
Those that occur in the abdomen are known as abdominal aortic aneurysms.
Abdominal aortic aneurysms are three times more common than thoracic aortic aneurysms, and nine out of ten develop below the level of the kidneys.
In the diagram, A shows a healthy aorta, B shows a thoracic aortic aneurysm and C shows an abdominal aortic aneurysm.
How common are aortic aneurysms?
One in every thousand people will develop an abdominal aortic aneurysm between the ages of 60 and 65, and this number continues to rise with age. Over the age of 65, an estimated 13% of men and 6% of women are affected.
Symptoms of aortic aneurysm
Most aortic aneurysms do not cause obvious symptoms. When symptoms are present, dilation of an abdominal aortic aneurysm may cause stretching pains in the abdomen, back or around the navel. You may also feel a pulsating sensation in the chest, abdomen, back or scrotum.
Symptoms of a thoracic aortic aneurysm may include coughing, hoarseness, shortness of breath, difficulty swallowing or stretching pain in the jaw, neck, back or chest.
These symptoms are often dismissed as indigestion or ‘one of those things’, but if you experience persistent pain or throbbing in the abdomen, chest or back, or a steady gnawing discomfort, it is important to tell your doctor.
Your doctor may feel a pulsating lump in the abdomen as a sign that an abdominal aortic aneurysm is present.
Risk of aortic aneurysm rupture
Once an aortic aneurysm expands to a diameter of 5.5cm there is a one in three chance that the weakness will rupture within the next 5 years. Routine ultrasound screening programs are therefore available in some countries to help detect these aneurysms before they become large enough to rupture.
Early detection and elective surgical repair can be life-saving.
Elective treatment of aortic aneurysm
Elective surgical grafting to re-line an aortic aneurysm is usually performed as a keyhole procedure, as this is safer and less invasive than the traditional open approach in which the abdominal wall is cut.
The newer endovascular techniques involve inserting a catheter up to the level of the aneurysm via arteries in the groin (A).
Once in place, a stent that is folded within the catheter is released and expanded to create a new aortic lining (B).
Elective repair is usually advised if an abdominal aortic aneurysm causes symptoms, if it is enlarging at a rate of more than one centimetre in diameter per year, or if it reaches 5.5cm in diameter.
Survival following planned, elective surgery, using the traditional open method, is 95.3%.
Survival with new, less invasive techniques, in which an abdominal aortic graft is inserted under X-ray control, via small incisions in the groin, is as high as 98.3%.
Ruptured aortic aneurysm
Having uncontrolled hypertension increases the likelihood that an aortic aneurysm will form and continue to dilate. If not detected via ultrasound screening, and repaired, the aneurysm may continue to dilate until it becomes weak enough to burst.
As blood pressure falls during deep sleep, then rises significantly before waking, the most common time for a weakened aortic aneurysm to rupture is early morning before 6am. A ruptured aortic aneurysm can occur at any time, however.
One in five aortic aneurysms rupture forward so that blood leaks under pressure into the abdominal or chest cavities. This is a catastrophic event and, sadly, few patients survive to reach hospital. Luckily, four out of five ruptured aneurysms leak backwards behind the peritoneal membrane (retroperitoneal space) where the resistance of surrounding tissues may slow blood loss long enough for emergency surgery to repair the rupture.
Overall, a ruptured aortic aneurysm is the 15th leading causes of death and become more common with increasing age. Men are four times more susceptible than women.
Symptoms of a ruptured aortic aneurysm
If an abdominal aortic aneurysm ruptures, or the wall splits into layers (dissection) symptoms can include:
- nausea or vomiting
- sudden severe pain in the lower abdomen or back
- feeling dizzy, clammy, light-headed with sweating skin
- a rapid heart rate when standing up
- collapse with a sudden low blood pressure (shock).
If a thoracic aortic aneurysm ruptures, or the wall splits into two or more layers (dissection) you may experience sudden, severe, sharp or stabbing pains in the chest or upper back which may move down towards the abdomen or into the arms.
The bottom line is, if you high a high blood pressure it’s important to take your medication as prescribed, and to make diet and lifestyle changes to reduce the chance of developing an aortic aneurysm.
If you notice persistent chest, back or abdominal symptoms, or feel a pulsating swelling in your chest or abdomen, seek medical advice. Early detection and monitoring can be life-saving.
Image credits: National Institutes of Health