What happens when the aorta – which ensures smooth blood flow throughout the body – malfunctions?
The aorta – extending from the heart to the abdominal area – is the largest artery in the body. It ensures that the blood brings oxygen from the heart to all parts of the body.
But like the rest of the body, it is susceptible to disease.
A common and serious condition is an aortic aneurysm, which happens when the aorta walls swell to more than 1.5 times their normal size, weakening the aorta. If it ruptures, blood spills into the body with serious – even fatal – consequences.
There are many causes. A common one is the accumulation of plague in the arteries (atherosclerosis) caused by untreated high blood pressure that weakens the artery walls.
Other causes include genetic disorders such as Marfan syndrome and Loeys-Dietz syndrome, which cause connective tissue in the blood vessel wall to develop abnormally.
Diagnosing the problem
There are two main types of aortic aneurysms – thoracic and abdominal – depending on where they occur in the aorta. The thoracic type affects the upper body, and the abdominal type happens closer to the belly area.
The thoracic type of ten goes undetected because there may be no symptoms, especially in the early stages, when the swelling is mild. As it progresses, the patient may begin to feel a deep pain in the chest, or have back pain, difficulty in swallowing, shortness of breath, cough or hoarseness in the voice. There could also be varying degrees of discomfort, depending on where and how severe the aneurysm is.
Aneurysms may first be picked up through a physical examination, blood pressure check, by heart murmurs or any pulsating lumps in the abdomen, groin or legs.
Subsequent tests such as coronary angiograms, echocardiograms, computed tomography or magnetic resonance imaging scans are done to confirm the diagnosis and monitor progression.
A ticking time bomb
If not diagnosed or treated, the aneurysm may weaken the inner wall of the aorta so much that it ruptures under the pressure of blood pushing against it, causing an aortic dissection. The patient may then feel a sudden ripping sensation in the chest, or severe pain between the shoulder blades.
If the aorta ruptures in the part closest to the heart, it is a Type A aortic dissection – a medical emergency that can be fatal if the patient does not get emergency surgery.
A Type B aortic dissection, while still serious, is usually not immediately lifethreatening. It happens when the affected site is beyond the blood supply to the left arm, a relatively “safe” distance from the heart. This is usually treated with medication, such as beta blockers, to lower the patient’s blood pressure and prevent a potentially deadly rupture in the aorta.
Aortic dissection, although associated with a high mortality rate, is also rare, affecting two to five out of every 100,000 individuals worldwide.
When the swelling in an aortic aneurysm is at risk of rupture, conventional open surgery can cure it. This involves reconstructing the affected area – “pipe change” using synthetic tubular grafts. Surgery of the aortic valve at the root of the aorta (nearest the heart) may be necessary if it is affected too.
The origins of coronary arteries that supply blood to the heart lie in close proximity to this valve at the aortic root. In some patients with extensive disease, coronary artery bypass grafting surgery restores blood circulation to the patient’s heart. This involves grafting a healthy artery or vein from the body to divert blood flow to the affected portions of the heart that lacks the blood flow.
During open “pipe change” surgery, all blood flow in the patient’s body will have to be halted for a limited duration. The patient’s core body temperature is reduced to induce a deep hypothermic state, which minimises the body’s energy requirements. This reduces the damage incurred by it being artificially put in a state of “suspended animation”.
In a less invasive form of surgery known as endovascular aneurysm repair, an expandable stent is placed within the affected portions of the aorta through punctures in blood vesels in the groin. This treatment is most common for the abdominal type of aortic aneurysm, or when the condition is amenable to this approach.
Prevention better than cure
To avoid a catastrophic crisis, it is important to heed tell-tale signs. This is especially so for men over the age of 60, smokers, or those with untreated high blood pressure and a family history of aortic disease.
Seek medical attention immediately if the chest or back pain increases in frequency, and there is difficulty in swallowing, shortness of breath, coughing or hoarseness of voice.
To reduce the risk or slow down the development of an aortic aneurysm, maintain a healthy lifestyle by eating well, exercising regularly, drinking in moderation, not smoking, and managing stress, blood pressure and cholesterol levels.
Extracted from Murmurs, a publication of the National Heart Centre Singapore (NHCS), with expertise from Associate Professor Soon Jia Lin, Senior Consultant, Department of Cardiothoracic Surgery, NHCS.