Aortic dissection symptoms
Aortic dissection symptoms
Aortic dissection is a condition which results from the tear in the tunica intima that leads to a surge of blood into the aortic wall. This will later lead to the formation of a false lumen from the the split that is formed between the outer part and the inner part of the tunica media. The blood will fill the false lumen and form hematoma. The continuous accumulation of blood in the false lumen will lead to a propagation of the dissection.
Aortic dissection is associated with smooth muscle of the aortic tunica media that undergoes degenerative changes. The risk factor for developing aortic dissection may include hypertension which accounts for 70% of patient with aortic dissection. Other risk factors may include , collagen abnormalities disorder ( Ehler - Danlos syndrome, Marfan syndrome, Noonan syndrome and Turner syndrome), inflammatory arthritis ( giant cell arteritis, tertiary syphilis and Takayasu arteritis ), congenital cardiovascular abnormalities ( bicuspid aortic valve, alpha 1 anti trypsin deficiency and coarctation of the aorta), trauma of the chest, aortic atherosclerosis, iatrogenic causes ( cardiovascular surgery, insertion of aortic balloon pump and angioplasty ), pregnancy, elderly and recreational drug use as well as smoking.
Aortic dissection is also associated with other condition such as syphilis, relapsing polychondritis, osteogenesis imperfecta, aortic stenosis and during pregnancy due to cystic medial necrosis.
Aortic dissection most commonly presents in people aged between 30 to 40 years old. It is also present in patients who suffer from Marfan syndrome. Male is more commonly affected than women. In terms of incidence 2000 new cases are diagnosed every year. 1 in 10 000 patients who are admitted to the hospital may suffer from aortic dissection. Aortic dissection is found in 1 in 350 patients at autopsy.
The patient typically presents with abrupt /sudden onset of sharp, stabbing, tearing pain from the anterior part of the chest which will radiate to the interscapular region on the back. The patient may also complain of back pain at the same time. This patient is typically presented with background history of hypertension. An elderly patient who suffers from aortic dissection is likely to suffer from past history of aneurysm, atherosclerosis or iatrogenic dissection. Suspicion of aortic dissection is raised with positive family history. Occlusion of the aorta and branches are commonly associated with aortic dissection. The patient may suffer from blackout, hemiparesis and dysphasia due to carotid artery obstruction. Angina or myocardial infarction is most commonly associated with coronary artery occlusion. Occlusion of the spinal artery may lead to paraplegia. Ataxia or syncope is associated with subclavian artery obstruction.Ischemic bowel or severe abdominal pain is associated with coeliac arteries obstruction. The patient may also suffer from anemia or renal failure as a result of renal artery occlusion.
On examination, the patient is presented with unequal pulse and blood pressure, wide pulse pressure, pulse deficit, pyrexia, hypotension or hypertension, early diastolic murmur (aortic regurgitation/insufficiency), dullness if the lung base (pleural effusion), cardiac tamponade, spinal cord defect/syndrome, symptoms and signs of congestive heart failure, limb ischemia, stroke and abrupt onset of sharp thoracic and abdominal pain.
In terms of pathology, aortic dissection is presented as cystic degeneration of tunica media ( cystic medial degeneration ). It consists of a fragment of elastic tissue that separates the elastic, muscular and fibrous element of the tunica media. In terms of gross pathology aortic dissection is classified according to Stanford classification and De Bakey classification. Stanford classification is more widely used. Type A Stanford classification involves the ascending aorta and its aortic arch while type B Stanford classification involves the descending aorta. De Bakey classification is divided into three types. Type 1 De Bakey classification is an aortic dissection that is originating from the ascending aorta and later propagates into the aortic arch. Type 2 De Bakey classification is an aortic dissection that is originating from the ascending aorta while Type 3 De Bakey classification is an aortic dissection that is originating from the descending aorta and propagates distally and proximally. 60% of aortic dissection affect the ascending aorta, 20% affect the descending aorta, 10% affect the aortic arch and the abdominal aorta and the remaining affect the ligamentum arteriosum as well as left subclavian artery. The cystic medial necrosis are most commonly seen in patients who suffer from Ehler - Danlos syndrome or Marfan syndrome where there is a defect in the connective tissue and elastin. Death is usually due to cardiac tamponade.
The investigation requires may include full blood count, ECG, chest X ray, trans esophageal echocardiography, chest CT scan, MRI scan and aortogram. The blood test may include monitoring the renal function ( urea and electrolyte studies) and cross match 10 units of blood. The ECG strip will show a pattern of left ventricular hypertrophy and if the dissection affecting the Ostia of the coronary artery the inferior myocardial infarction pattern is noted. The pattern of nonspecific ST-T changes or ischemic changes may also present on the ECG strip.
The chest X ray may reveal a localized bulging of the aortic arch as well as widening of the mediastinum . Besides that double density of the descending aorta and irregular aortic contour and rightwards displacement of the aorta as well as pleural effusion can also be detected.
The tests of choice for detecting aortic dissection in an unstable patient may include trans esophageal echocardiography . It is useful in detecting cardiac complication . However it is limited in evaluating the thoracic aorta . Spiral CT scan is a sensitive and specific in detecting aortic dissection than chest CT scan. If the patient is hemodynamically stable , MRI scan is the test of choice for delineation of the vascular anatomy.
Cardiac catheterization or aortogram is on one of the invasive method that is useful in evaluating aortic dissection. This procedure allows us to detect any intimal flap, compression of true lumen, the present of 2 lumens and any alteration of flow pattern as well as ulcer like projection.
The differential diagnosis of aortic dissection may include pulmonary embolism, pleurisy, pneumonia, pericarditis, aortic regurgitation, myocardial infarction, musculoskeletal pain , acute pancreatitis, cholecystitis, angina , atherosclerosis embolism and penetrating peptic ulcer.
The management of aortic dissection involves admitting the patient to the intensive care unit where the patient blood pressure, pain level and hemodynamic stability is assessed. Intubation is performed in a patient who is hemodynamically unstable. Intravenous access is established ( central or arterial lines). Fluid replacement with colloid solution and blood product is given to the patient. Cross match 10 units of blood is performed for blood transfusion. Pain reliever such as diamorphine is also given to the patient. The patient's pulse, blood pressure and central venous pressure of the patient are monitored. Urinary output is monitored using urinary catheter. The blood pressure needs to be controlled. The target blood pressure is 100-120mmHg and the blood pressure is controlled with IV labetalol/beta blocker or sodium nitroprusside. Alternatively diltiazem or verapamil can be used to achieve a heart rate around 60 beats per minute. Inotropes are avoided if the patient is hypotensive. The hypotensive condition is treated by correcting the predisposing factors such as blood loss, cardiac tamponade and heart failure. The patient is carefully observed for any evidence of organ dysfunction such as renal failure with Foley catheter to follow the urine output. Any neurological signs or impairment is observed. Swan - Ganz catheter is used to monitor the cardiac filling pressure and performance as a result of cardio depressive or vasoactive drugs.
Medical therapy is the treatment of choice of aortic dissection without cardiac complication. It depends on the shearing force of myocardial contraction and the decreasing blood pressure. Medical therapy is useful for Stanfard classification Type B or De Bakey classification type 3.
The medical treatment involves the control of blood pressure and prevent further dissection with intravenous labetalol and sodium nitroprusside. The patient is advised not to take anything orally until surgical evaluation is complete
Surgery is the treatment of choice for aortic dissection that affect the ascending aorta in 80% of cases ( Stanford classification Type A) It is a surgical emergency and it is performed to avoid the risk of developing myocardial infarction, cardiac tamponade and aortic regurgitation. A tube graft is replacing the affected aorta. The aortic valve replacement is also performed. Hemorrhagic stroke is a relative contraindication for the patient who is undergoing surgical repair due to its intra operative anticoagulant risk.
In some cases, Type B aortic dissection may require surgical intervention. These conditions are due to bleeding into the pleural space, continued aortic expansion, extension of dissecting, occlusion of major aortic branch and impending rupture as well as inability to control pain. Stent grafting and endovascular stenting are another form of alternative treatments.
The complication of aortic dissection may include obstruction of spinal, mesenteric, carotid, renal and subclavian arteries as well as myocardial infarction, pulmonary edema, cardiac tamponade and aortic rupture.
The patient is admitted to the hospital if there is any complaint of thoracic or abdominal pain with evidence of pulse deficit. The prognosis of surgical success is poor in cases of abrupt onset of chest pain, the age of the patient is more than 70 years old, renal failure, abnormal ECG with ST elevation, cardiac tamponade, hypertensive or hypotensive patient and any underlying pulmonary disease. Untreated patient the mortality is around 90% in 3 months, 60% in 2 weeks and 33% in 24 hours. 70% of patient will survive with medical and surgical treatment. Mortality is around 29% - 38% in the dissection of ascending aorta which is treated surgically. 10 years survival rates is 40% of the patient who is treated surgically. 10 years survival rates is similar in both medical and surgical treatment. Risk of re dissection for 5 years are 13% and 23% for 10 years.
Patient with dissection of aorta will require regular follow up visit of 1 months than 3 month interval. During the follow up, check and pay careful attention for the back and chest pain, and signs and symptoms of aortic insufficiency as well as development of the saccular aneurysm on chest film. Routine chest CT scan or chest film may be appropriate for a patient who is medically treated. Systolic blood pressure is maintained at 120mmHg /16kPa.
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