Aortic dissection resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Chetan Lokhande, M.B.B.S [2]

Overview

Aortic dissection is a tear in the layers of the aorta especially in the intima leading to bleeding and separation of the layers of the aorta from within which creates a false lumen. Aortic dissection is a medical emergency and can quickly lead to death, even with optimal treatment, as a result of decreased blood supply to other organs, cardiac failure, and sometimes rupture of the aorta. Diagnosis is made with imaging studies like Transesophageal echocardiography (TEE), Computed tomography (CT) or Magnetic resonance imaging (MRI). Treatment depends according to the anatomic location of the aorta involved. Surgery is usually required for dissections that involve the aortic arch, while dissections of the part further away from the heart may be treated with antihypertensive medications.

Aortic dissection can be further classifies as:

1. Acute aortic dissection- Dissection occurring within 2 weeks of onset of pain
2. Subacute aortic dissection-Dissection occurring witin 2-6 weeks of onset of pain
3. Chronic aortic dissection- Dissection occurring within 6 weeks of pain.

Classification

Aortic dissection can be classified into four types. DeBakey and Daily (Stanford) systems are the commonly used systems used to classify aortic dissection.

• Stanford system classifies dissection into the following two types based on whether ascending aorta is involved or not.

1. Ascending aortic dissection or type A
2. All other dissections or type B

• DeBakey system classifies dissection according to location of the tear.

1. Type I- Starts at ascending aorta and extends upto the aortic arch
2. Type II- Starts and is limited till the ascending aorta
3. Type III- Starts in the descending aorta and progresses proximally or distally
   1. Type III A - Restricted till the descending thoracic aorta
   2. Type III B - Dissection extending below the diaphragm

• The third type of classification divides aortic dissection according to the proximity

1. Proximal- Ascending aortic involvement
2. Distal- Descending aortic involvement distal to left subclavian artery

Causes

Life Threatening Causes

Aortic dissection is a life-threatening condition and must be treated as such irrespective of the causes. Life-threatening conditions may result in death or permanent disability within 24 hours if left untreated.

Common Causes

• Atherosclerosis
• Complication of cardiac procedures
• Chest trauma
• Connective tissue disorders
• Hypertension
• Vasculitis

Management

Shown below is a diagnostic algorithm depicting the management of Aortic dissection according to the Guidelines for Diagnosis and Management of patients with Thoracic Aortic Disease.

Characterize the symptoms: ❑ Cardiac ❑ Chest pain described as tearing, ripping, sharp or stabbing* ❑ Abrupt onset of pain and increasing in intensity* ❑ Chest pain worsened by deep breathing or cough and relieved by sitting upright ❑ Anxiety ❑ Palpitation ❑ Fainting ❑ Sweating ❑ Pale skin ❑ Rapid, weak pulse ❑ Shortness of breath ❑ Peripheral edema ❑ Rapid breathing ❑ Orthopnea ❑ Extra cardiac ❑ Abdominal pain or back pain ❑ Flank pain ❑ Lower and upper extremity weakness, numbness and tingling ❑ Nausea and vomiting ❑ Symptoms suggestive of stroke ❑ Swallowing difficulties due to pressure on the esophagus ❑ Gastrointestinal bleeding ❑ Altered mental status ❑ Feeling of impending doom ❑ Hemoptysis ❑ Drooping of eyelids ❑ Decreased or no sweating ❑ Haematemesis ❑ Hoarseness of voice

Obtain a detailed history: ❑ Past medical history ❑ Hypertension ❑ Pheochromocytoma ❑ Family history ❑ Aortic disorder* ❑ Connective tissue disorder* ❑ Anatomic deformities ❑ Aortic valve disease* ❑ Thoracic aortic aneurysm* ❑ Coarctation of aorta ❑ Polycystic kidney disease ❑ Iatrogenic ❑ Recent aortic manipulation* ❑ Chronic steroid usage ❑ Immunosuppressive therapy ❑ Lifestyle ❑ Cocaine abuse ❑ Heavy weight lifting ❑ Trauma ❑ Genetic ❑ Marfan's syndrome* ❑ Ehlers-Danlos syndrome ❑ Turners syndrome ❑ Biscuspid aortic valve ❑ Loeys-Dietz syndrome ❑ Familial thoracic aneurysm and dissection syndrome ❑ Inflammatory vasculitis ❑ Takayasu arteritis ❑ Giant cell arteritis ❑ Behcet's arteritis ❑ Pregnancy ❑ Infections involving the aorta

Examine the patient: ❑ General examination: ❑ Pulse rate - ↑ ❑ Blood pressure - ↑ or ↓ ❑ Respiratory rate - ↑ ❑ Wide pulse pressure ❑ Difference in the blood pressure in both extremities* ❑ Signs of shock (hypoperfusion)* ❑ Pulse deficit involving carotid, femoral or subclavian arteries* ❑ Increased sweating or anhidrosis ❑ Head/neck examination: ❑ ↑ JVP ❑ Signs of vocal cord paralysis ❑ Pemberton's sign ❑ Venous distention in the neck and distended veins in the upper chest and arms (Superior vena cava syndrome) (SVC) ❑ Cardiovascular examination: ❑ Diastolic murmur suggestive of aortic regurgitation* ❑ Wheeze (cardiac asthma) (CHF) ❑ Pericardial friction rub ❑ Respiratory examination ❑ Crackles / crepitations / rales ❑ Decreased movement of the chest on affected side ❑ Stony dullness to percussion ❑ Diminished breaths sounds ❑ Decreased vocal fremitus ❑ Pleural friction rub. ❑ Abdominal examination: ❑ Ascites ❑ Claudication of buttocks ❑ Absent femoral pulses ❑ Neurological examination: ❑ Altered mental status* ❑ Signs of peripheral neuropathy ❑ Signs suggestive of stroke* ❑ Extremity examination: ❑ Pedal edema ❑ Ophthalmological examination ❑ Miosis ❑ Ptosis

❑ Assess the severity by counting the high risk features marked in bold and by *

Consider alternate diagnosis: ❑ Aortic regurgitation ❑ Aortic stenosis ❑ Aortic aneurysm ❑ Atherosclerotic or cholesterol embolism ❑ Cardiac tamponade ❑ Cardiogenic shock ❑ Cholecystitis ❑ Esophageal perforation or rupture ❑ Gastroenteritis ❑ Hemorrhagic shock ❑ Hernias ❑ Hypertensive emergencies ❑ Hypovolemic shock ❑ Musculoskeletal pain ❑ Mediastinal tumors ❑ Myocardial infarction ❑ Myocarditis ❑ Myopathies ❑ Pancreatitis ❑ Pericarditis ❑ Pleuritis ❑ Peptic ulcer disease or perforating ulcer ❑ Peripheral vascular injuries ❑ Pleural effusion ❑ Pulmonary embolism ❑ Thoracic outlet syndrome

Low Risk ❑ No high risk features present ❑ Clinical presentation is not initially suggestive for dissection but aortic imaging may help in the absence of alternative diagnosis

Intermediate Risk ❑ Single high risk present ❑ Concerning presentation for acute dissection and requires aortic imaging if no alternate diagnosis can be reached

High Risk ❑ Two or more high risk features present ❑ Acute dissection requiring immediate surgical evaluation and expedited aortic imaging

❑ Can alternate diagnosis be ruled out

❑ Order an EKG ❑ Does EKG show ST elevation

Yes

No

Yes

No

❑ Consider immediate surgical consultation and accelerate aortic imaging

❑ Treat accordingly

❑ Order a chest X-ray ❑ Check Vitals specially blood pressure for hypotension ❑ Is there evidence of ❑ Hypotension ❑ Widened mediastinum

❑ Initiate appropriate therapy ❑ Check whether it helped to alleviate the symptom If no then order

❑ Order a coronary angiography and Treat like a primary acute coronary syndrome (ACS) unless perfusion deficits are present then consider immediate coronary reperfusion therapy ❑ Can the lesion be identified by coronary angiography

No

Yes

Yes

No

❑ Evaluate clinical scenario for risk factors for Thoracic Aortic Disease (TAD) ❑ Advanced age ❑ Risk factor for aortic diseases ❑ Syncope

Detailed and accelerated aortic imaging

❑ Do a detailed aortic imaging for thoracic aortic disease

❑ Accelerated aortic Imaging ❑ Transesophageal echocardiography (TEE) (Done in an emergency or unstable patient) ❑ Computed tomography (CT) ❑ Magnetic resonance imaging (MRI) (Can visualize aorta from chest to pelvis)

❑ Can aortic dissection be confirmed by imaging study

Yes

No

❑ Start appropriate therapy

❑ Obtain a secondary imaging study if there is high cinical suscpicion even if the initial aortic imaging studies are negative

Shown below is an algorithm depicting the medical management of Aortic dissection according to the Guidelines for Diagnosis and Management of patients with Thoracic Aortic Disease.

❑ Imaging study confirms aortic dissection ❑ Check whether dissection occurred in ascending aorta

Yes

No

❑ Start Medical management

❑ Check Vitals ❑ Specially blood pressure in both arms ❑ Take the highest reading for treatment or goal therapy ❑ Patient hemodynamically stable

Yes

No

❑ Control rate and pressure ❑ I.V Beta blocker or labetalol ❑ Substitute diltiazem and verapamil If betablockers are contraindicated ❑ Goal Heart rate should be 60 beats per minute ❑ Pain control ❑ Use Opiates

❑ Type B dissection ❑ Intravenous fluid replacement ❑ Maintain mean arterial pressure (MAP) of 70 mm of hg ❑ Start vasopressor if still hypotensive ❑ Find out etiology of hypertension ❑ Imaging to find out contained rupture ❑ Perform Transthoracic echocardiogram (TTE) to assess cardiac function ❑ Consider surgical evaluation

❑ Type A dissection ❑ Expedited surgical consultation and consider surgery (Urgent) ❑ Maintain Euvolemic status ❑ Intravenous fluid replacement ❑ Maintain mean arterial pressure (MAP) of 70 mm of hg ❑ Rule out complications using imaging study ❑ Pericardial tamponade ❑ Rupture of aorta ❑ Aortic insufficiency

No

❑ Can the cause of hypotension respond to surgical management

❑ Monitor vitals closely ❑ Maintain systolic BP <120 mm of hg

Yes

Yes

No

❑ Check whether dissection involves ascending aorta

No

Yes

❑ Control blood pressure ❑ Intravenous vasodilator

❑ Monitor vitals closely ❑ Maintain systolic BP <120 mm of hg

❑ Check for any complications which might require surgery ❑ Malperfusion ❑ Progressing dissection ❑ Expansion of aortic aneurysm ❑ Uncontrolled or refractory hypertension

Yes

❑ Consider surgical management

No

❑ Switch to oral medications ❑ Betablockers ❑ Antihypertensive regimen ❑ Follow up in the outpatient

Shown below is an algorithm depicting the surgical management of Aortic dissection according to the Guidelines for Diagnosis and Management of patients with Thoracic Aortic Disease.

❑ Imaging study confirms aortic dissection ❑ Check whether dissection occurred in ascending aorta

No

Yes

❑ Assess suitability for surgery ❑ Patient stable for pre-op testing?

No

Medical management

Yes

❑ Age>40?

No

Yes

❑ Assess need for pre-operative coronary angiography ❑ Known CAD? ❑ Significant risk factors for CAD?

No

Yes

❑ Perform angiography Is significant CAD detected on angiography?

No

Yes

❑ Plan for CABG at the time of aortic dissection repair

❑ Perform urgent operative management

❑ Perform intra-operative assessment of aortic valve by TEE for presence of one of the following: ❑ Aortic regurgitation ❑ Dissection of aortic sinuses

No

Yes

❑ Perform graft replacement of ascending aorta ± aortic arch

❑ Perform graft replacement of ascending aorta ± aortic arch ❑ Consider repair/replacement of aortic valve

Do's

History and Examination

• For pre-test risk determination include information about:
  • Medical History
  • Family history and ask specifically for family history of aortic dissection or thoracic aneurysm
  • Pain history
• Do a detailed physical examination to identify findings for certain high risk conditions like: (class I, level of evidence B)
  • Marfan's syndrome
  • Loeys-Dietz syndrome
  • Ehlers-Danlos syndrome
  • Turner's syndrome
  • Connective tissue disorder
• Check for genetic mutations predisposing to dissection: (class I, level of evidence B)
  • Fibrillin 1 (FBN1)
  • Transforming growth factor, beta receptor I (TGFBR1)
  • Transforming growth factor, beta receptor II(TGFBR2)
  • Alpha-actin-2(ACTA2)
  • Myosin-11 (MYHH11)
• Any 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)
  • Onset of pain whether abrupt or instantaneous
  • Severity of pain
  • Quality of pain whether ripping, tearing,stabbing or sharp.
• Check for the following features on examination: (class I, level of evidence B)
  • Pulse deficits
  • Blood pressure (systolic) difference of above 20 mm of hg in limbs
  • New aortic regurgitation features
  • Focal neurological deficit
• Patients less than 40 years of age and presenting with sudden 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)

Screening Tests

• Do an EKG on all patients with dissection symptoms. (class I, level of evidence B)
• If ST elevation is present in EKG then treat the patient as an acute cardiac event unless the patient has high risk factors for acute dissection.
• If EKG shows ST elevation with no dissection features then perform a coronary angiography and then do a thrombolysis or percutaneous coronary intervention.
• Do a X-ray for all patients with intermediate risk and low risk to rule out alternate diagnosis. (class I, level of evidence C)
• High risk patients should be evaluated 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 there is high cinical suscpicion even if the initial aortic imaging studies are negative. class III, level of evidence C

Initial Management

• 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)
• If beta blockers are contra indicated then use nondihyropyridine calcium channel blockers to control rate. (class I, level of evidence C)
• If BP remains above 120 mm of hg even after medical treatment then use angiotensin converting enzyme and other vasodilators to maintain end organ perfusion. (class I, level of evidence C)

Definitive Management

• Do 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)
• Do an emergent repair in acute dissection of ascending aorta to prevent complications like rupture. (class I, level of evidence C)
• Treat all descending aorta medically unless complicated by life threatening conditions like perfusion deficit, dissection enlargement, aneurysmal enlargement or blood pressure refractory to treatment. (class I, level of evidence C)
• Do a definitive aortic imaging study as soon as Chest X-ray suggests widened mediastinum.
• Goal should be to maintain heart rate less than 60 beats / minute and blood pressure between 100 and 120 mm hg.
• Use Esmolol if asthma, congestive heart failure or chronic obstructive pulmonary disease.
• Use Labetalol to maintain heart rate and blood pressure, it prevents usage of another vasodilator.
• Do pericardiocentes for pericardial bleeding and dissection related hemopericardium.
• Do a plasma smooth muscle myosin heavy chain protein, D-dimer and high sensitive C-reactive protein to rule out alternate diagnosis.

Dont's

• Don't use beta blocker in patients having aortic regurgitation as they may block the tachycardia caused by compensation.
• Don't use vasodilator before heart rate is controlled otherwise there would be reflex tachycardia which would increase the stress on aorta and worsening the dissection.
• Use Sodium nitroprusside as the first line for treating hypertension. Nicardipine, nitroglycerin and fenoldopam are other drugs used to treat hypertension.
• Don't delay aortic imaging even if chest x-ray is negative. (class III, level of evidence C).