What is aortic dissection? An aortic dissection is a potentially fatal condition in which, through a tear in the inner layer of the aortic wall, blood enters between the middle and outer layers separating (or dissecting) them.

• Deterioration of the arterial wall due to high blood pressure is the most common reason for aortic dissections.
• A severe pain appearing suddenly across the chest and at the back may indicate an aortic dissection.
• X-rays and CT scans help with diagnosis and assessment of the extent and location of the damage.
• Antihypertensive drugs and surgical repairs constitute the treatment.

 Blood leaking out through a tear in the inner wall of the aorta, results in the separation or dissection of the middle and outer layers, forming a pocket of blood there. Men are 3 times more prone to this condition, which usually occurs in the age group of 40 to 70. While its occurrence is less common in Asians; blacks, especially African- Americans are predisposed to this condition.

Deterioration of the walls of the aorta due to high blood pressure is the most common cause of aortic dissection, accounting for two thirds of the cases. Connective tissue disorders, especially the inherited condition called Marfan syndrome, predispose people to aortic dissection. Patent ductus arteriosus and coarctation of aorta and aortic valve defects are some of the congenital abnormalities that may cause an aortic dissection. Atherosclerosis and severe injury to chest also may be a cause. Accidental injury during a catheterization procedure such as angiography or other surgical procedures also may result in aortic dissection.

Symptoms

Severe ripping pain appearing suddenly across the chest and sometimes high up at the back is the symptom of aortic dissection. The pain also spreads along with the extension of the dissection.

Blockages can occur at the branching of the arteries when the dissection reaches there, cutting off blood supply to the different areas supplied by those arteries. When renal arteries are affected, it results in pain in the lower back area. Blockage in spinal arteries may cause freezing of limbs or tingling sensation in them. Abdominal pain results from blockage in the mesentery arteries which supply to the intestines. Heart attack and stroke are the outcomes of blocks in coronary and cerebral arteries respectively.

A leaking dissection causes accumulation of blood in the chest, which leads to pericardial effusion that may steadily worsen to cause cardiac tamponade. This potentially fatal condition requires immediate intervention.

Many of the symptoms appearing due to aortic dissection may resemble symptoms of other conditions, but there are certain symptoms which are characteristic of this particular condition. So, doctors can often diagnose an aortic dissection from those symptoms. Pulse may become undetectable or decreased in the limbs, in two thirds of cases. When dissection extends towards the heart, a stethoscope can detect a distinct murmur.

Aortic dissection can be detected by chest x-rays which shows an enlargement in the aorta but it cannot be considered as a foolproof confirmation. A trans-esophageal echocardiography with the ultrasound probe inserted into the esophagus, can detect dissections, especially in the first part of the aorta. But a CT scan is the ideal test, to detect the location and assess the extent of the dissection when it is done after the injection of a radio opaque dye.

Prognosis and Treatment

Prognosis is poor for people who do not get the right treatment; three fourths of them succumbing to it within two weeks. The death may be caused either due to the issues directly related to the dissection or due to other disorders precipitated or worsened by the dissection.  About 40% of those who get treatment, if they survive the first two weeks, have a good prognosis of extended life of up to ten years. The other 60% may not live beyond five years even with continued medication. People who have dissection in parts of aorta farther away from the heart have a better prognosis, than those who have aortic dissections much closer to the heart.

Drug treatment is started as soon as the patients are admitted in the intensive care unit for continuous monitoring, since aortic dissection can become suddenly fatal. A beta blocker and nitroprusside are administered intravenously to lower blood pressure and heart rate to the minimum possible levels needed to maintain life. In the meantime, doctors assess the need and suitability of surgical options.

For the part of aorta immediately after its emergence from the heart, surgery is the usual option considered by doctors. Drug therapy is initiated for dissections appearing in areas of the aortic artery further away from heart. But, if there is a leak in the artery causing internal bleeding, it has to be repaired surgically. If there is progression in the dissection or if blood supply to the limbs or important internal organs is compromised, immediate surgery may become necessary. For people with Marfan syndrome, doctors do not wait and watch, and surgery is always recommended to prevent avoidable emergencies. Surgery of the areas away from heart is riskier than the surgeries for dissections much more closer to the heart, the risk for the latter being around 15%.

Part of the affected artery is removed and the rest is repaired by closing the false channel that had developed due to dissection. Using a synthetic graft which provides strength and structural support, the walls of the aorta are reconstructed. The aortic valve is either repaired or replaced, if there is valve dysfunction and regurgitation. This surgery is time consuming, extending up to 6 hours. Prolonged hospital stay of over a week is also required. Endovascular stent grafting is a newer option, in which a catheter threaded up the femoral artery, carries a collapsible stent to the location of the dissection. The stent is enlarged at the site to repair the damaged aorta. It usually gets over in two to four hours and hospital stay is also reduced to less than three days.

Drugs to keep the blood pressure low, is an integral part of treatment, even after surgical correction of aortic dissections, as it helps to lower the stress inflicted on the walls of the aorta. An ACE inhibitor, in addition to one of the drugs belonging to either calcium channel blockers or beta-blockers, is taken for life. People with atherosclerosis are given anti-cholesterol medication and are advised to make suitable diet modifications.

Patients who have undergone surgical repair of dissections should be monitored at regular intervals to detect complications. Recurrence of dissection and formation of aneurisms, which may result in aortic valve dysfunction and regurgitation, are possible complications which should be treated promptly.

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Yasser Elnahas

MD, PHD, Professor Of CardioVascular Surgery

Dr. Yasser Elnahas, Is an associate Professor of Cardiovascular Surgery. Dr. Elnahas was trained as a fellow At Texas Heart Institute And Mayo Clinic Foundation.Dr. Elnahas is dedicated to educating the general public about different disease conditions and simplifying the medical knowledge in an easy to understand terminology.

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