Aortic dissection resident survival guide
|Aortic dissection resident survival guide Microchapters|
Aortic dissection (AD) is a disruption of the medial layer of the aorta triggered by intramural bleeding. It is commonly due to an intimal tear that causes tracking of blood in a dissection plane within the media. Blood accumulation results in a separation of the aortic wall layers with ensuing formation of a true lumen and a false lumen with or without communication between the two. Aortic dissection is a medical emergency and can quickly lead to death if not treated urgently. Patients classically present with abrupt onset of severe, knife-like chest (most common), back, or abdominal pain. Other important features that increases the probability of aortic dissection include pulse deficits, systolic blood pressure differences between limbs, focal neurologic deficits, new aortic murmurs, shock, and a history of connective tissue disease and aortic valve disease. CT, MRI, or transesophageal echocardiography (TEE) may be used for the diagnosis AD, although CT is preferred because of it's speed, excellent sensitivity, and superiority in diagnosing arch vessel involvement. Serial imaging is recommended to monitor for progression of the dissection. After excluding possible aortic regurgitation, intravenous beta-blockers should be initiated in all patients to reduce the systolic blood pressure (SBP) to 100 to 120 mmHg and controlling the heart rate, to minimize the shear stress on the aortic wall. Treatment depends on the anatomic location of the dissection and complications. Uncomplicated type B dissections should be treated medically whereas type A dissections and complicated type B dissections should be treated surgically. Complications of AD include aortic regurgitation, myocardial ischaemia or infarction, pleural effusion, stroke, mesenteric ischemia, and acute kidney injury.
Originate in the descending aorta (distal to left subclavian artery) and propagate distally, rarely extends proximally (include Debakey type IIIa and IIIb, and Stanford type B)
Click here for the detailed classification schemes.
Life Threatening Causes
Aortic dissection is a life-threatening condition and must be treated as such irrespective of the underlying cause.
- Hypertension (underlying cause in 70% of cases)
- Pre-existing aortic diseases or aortic valve disease
- Blunt chest trauma
- Complication of cardiac procedures
- Connective tissue disorders
- Intravenous drug use (cocaine and amphetamines)
Click here for the complete list of causes.
FIRE: Focused Initial Rapid Evaluation
A Focused Initial Rapid Evaluation (FIRE) should be performed to identify patients in need of immediate intervention.
Boxes in red signify that an urgent management is needed.
Abbreviations: AVR: Aortic valve replacement; BP Blood Pressure, CCU:
Coronary care unit; CHF: Congestive cardiac failure; CXR: Chest X-ray; EKG: Electrocardiogram; MI: Myocardial infarction; OR: Operating room; TAVR: Transcatheter aortic valve replacement; TEE: Transesophageal echocardiogram; TTE: Transthoracic echocardiogram; HEENT: Head eye ear nose throat
Identify cardinal findings that increase the pretest probability of acute aortic dissection
❑ Chest pain or back pain or abdominal pain
Does the patient have the following findings which require urgent management?
Attempt to stabilize patient
❑ Attend to the patient's ABCs (Airway, Breathing, Circulation)
❑ Obtain 12 lead ECG and place the patient on a cardiac monitor
Control blood pressure
❑ Beta blockers are first-line agents, as they circumvent the reflex tachycardia associated with blood pressure lowering
❑ Substitute with non-dihydropyridine calcium channel blockers if beta-blockers are contraindicated
❑ Morphine sulphate
Urgent imaging required
Can aortic dissection be confirmed?
Obtain a secondary imaging study, if there is high clinical suspicion
Complete Diagnostic Approach
A complete diagnostic approach should be carried out after a focused initial rapid evaluation is conducted and following initiation of any urgent intervention.
Characterize the symptoms:
❑ Chest pain
❑ Neck, throat, and jaw pain
Obtain a detailed history:
❑ Past medical history
❑ Family history
❑ Anatomic defects
❑ Social history
❑ Inflammatory vasculitis
Examine the patient:
❑ Obtain vitals:
❑ Perform a HEENT examination looking for:
❑ Perform a cardiovascular examination looking for:
❑ Perform a respiratory examination looking for:
❑ Perform an abdominal examination looking for:
❑ Perform a full neurological examination looking for:
❑ Examine the extremities for:
Consider alternate diagnosis:
Focused bedside pre-test risk assessment
❑ High risk conditions
❑ High risk pain features
❑ High risk exam features
Low pre-test probability
(No features present)
High threshold for aortic imaging
Intermediate pre-test probability
(1 feature present)
Intermediate threshold for aortic imaging
High pre-test probability
(2 or more features present)
Immediate surgical evaluation and expedited aortic imaging
|❑ Can an alternate diagnosis be identified?||❑ Order an EKG
❑ Does EKG show ST elevation ?
❑ Consider immediate surgical consultation and do aortic imaging as soon as possible
❑ Can an alternate diagnosis be identified?
Detailed and accelerated aortic imaging
|❑ Can aortic dissection be confirmed by imaging study|
|❑ Start appropriate therapy|
❑ Obtain a secondary imaging study if there is high clinical suspicion, even if the initial aortic imaging studies are negative
Shown below is an algorithm summarizing the medical management of aortic dissection according to the 2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM guidelines for Diagnosis and Management of patients with Thoracic Aortic Disease.
Confirmed aortic dissection
❑ Consider urgent surgical consultation
❑ Consider transfer to other medical facility if resources not available for adequate management
❑ Is patient hemodynamically stable ?
Control rate and pressure
(choose ONE of the following agents)
Substitute with non-dihydropyridine calcium channel blockers if betablockers are contraindicated
❑ Type A dissection
❑ Surgical emergency, expedited transfer to operating room
❑ Type B dissection
❑ Intravenous fluid replacement
❑ Rule out a possible complication causing hypotension:
|Systolic blood pressure still >120 mm Hg?||No||Yes||Can hypotension be corrected by surgical intervention?|
Add IV vasodilator with SBP goal <120 mmHg
(involving ascending aorta)?
|Yes||Proceed to Surgical Management|
❑ Continue medical management
❑ Maintain SBP<120 mm Hg
❑ Continue medical management
❑ Maintain SBP<120 mm Hg
❑ Complications that require operative or interventional management?
Refer for surgical management
Is the patient hemodynamically stable?
❑ Age > 40?
❑ Plan for CABG at the time of aortic dissection repair
❑ Perform urgent operative management
History and Examination
- For pre-test risk determination include information about:
- Do a detailed physical examination to identify findings for certain high risk conditions like:(class I, level of evidence B)
- Check for genetic mutations predisposing to dissection:(class I, level of evidence B)
- Ask about recent aortic or surgical or catheter manipulation.(class I, level of evidence C)
- Ask in detail about the pain. Include the following: (class I, level of evidence B)
- Check for the following features on examination:(class I, level of evidence B)
- Patients less than 40 years of age and presenting with sudden onset chest, abdominal or back pain should be evaluated for high risk conditions.
- Patients presenting with features of syncope along with features of dissection should have a detailed neurological examination and cardiovascular examination to rule out pericardial tamponade and other neurological deficits.(class I, level of evidence C)
- Do an emergent CT or a transesophageal echocardiography (TEE). If the patient is hemodynamically unstable, then a transesophageal echo can be performed in the operating room after the patient has been induced and is being prepared for surgery.
- Do a magnetic resonance imaging contrast aortography (MRI) only if:
- Do an EKG when patients presents with symptoms of dissection.(class I, level of evidence B)
- Treat the patient as an acute cardiac event, if ST elevation is present in EKG then, unless the patient has high risk factors for acute dissection.
- Order an X-ray for all patients with intermediate to low risk to rule out an alternate diagnosis.(class I, level of evidence C)
- Evaluate high risk patients by transesophageal echocardiogram, computed tomography or magnetic resonance imaging to rule out dissection.(class I, level of evidence B)
- Obtain a secondary imaging study, if the initial aortic imaging studies are non conclusive, and there is a high clinical suspicion.(class III, level of evidence C)
- Do a plasma smooth muscle myosin heavy chain protein, D-dimer and high sensitive C-reactive protein to rule out alternate diagnosis.
- Medical management should be aimed at decreasing aortic wall stress.(class I, level of evidence C)
- Titrate beta blocker to maintain heart rate of 60 beats/minute.(class I, level of evidence C)
- Use nondihyropyridine calcium channel blockers to control rate, if beta blockers are contraindicated.(class I, level of evidence C)
- Use angiotensin converting enzyme (ACE) inhibitors or vasodilators to maintain end organ perfusion, if BP remains above 120 mm of Hg, after medical treatment.(class I, level of evidence C).
- Do a pericardiocentesis for pericardial bleeding and dissection related hemopericardium.
- Order a surgical consultation for all patients once diagnosed with aortic dissection. This applies to patients presenting with dissection at any location. (class I, level of evidence C)
- Perform an emergent repair in acute dissection of ascending aorta to prevent complications like rupture.(class I, level of evidence C)
- Consider surgical repair for all type A dissections as they involve the aortic valve. type A|Ascending aortic dissections (Type A Stanford)]] often involve the aortic valve, which having lost its suspensory support, telescopes down into the aortic root, resulting in aortic incompetence. This needs re-suspending to re-seat the valve and repair / prevent coronary artery injury. The area of dissection is removed and replaced with a dacron graft to prevent further dissection from occurring.
- Suspect malperfusion in type B aortic dissection, if following sings are present, Refractory hypertension (decreased renal perfusion), tensed abdomen, progressive metabolic acidosis, increasing liver enzymes (impaired perfusion of truncus celiacus, mesenteric arteries).
- Consider medical management for type B dissections, unless there is leaking, rupture or compromise to other organs, e.g. kidneys and life threatening conditions like perfusion deficit, dissection enlargement, aneurysm enlargement or blood pressure refractory to treatment.(class I, level of evidence C)
- Perform an MRI before discharge and repeat at 6 mo and 1 yr, then every 1 to 2 yr.
- Don't delay aortic imaging even if chest x-ray is negative (class III, level of evidence C).
- Don't use beta blocker among patients with severe acute aortic regurgitation as they inhibit the compensatory tachycardia needed to maintain cardiac output.
- Don't use nitroprusside without a β-blocker or non-dihydropyridine calcium channel blocker in order to prevent reflex sympathetic activation which can increase aortic shear stress and potentially worsen the dissection.
- Hemorrhagic stroke is a relative contraindication to urgent surgical intervention done for type A tears, as intraoperative heparinization and restoration of cerebral blood flow can worsen ongoing stroke outcomes.
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