Aortic Dissection

Epidemiology

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Risk Factors

Aortic Coarctation (see Aortic Coarctation)
Aortic Instrumentation/Surgery
- Abdominal Aortic Aneurysm Repair (Open or Endovascular)
- Cardiac Catheterization (see Cardiac Catheterization)
- Cardiac Surgery
- Carotid Repair
- Thoracic Aortic Aneurysm Repair
Atherosclerosis: present in most cases
Bicuspid Aortic Valve (see Bicuspid Aortic Valve)
Genetically-Mediated Collagen Disorders
- Annuloaortic Ectasia
- Ehlers-Danlos Syndrome (see Ehlers-Danlos Syndrome)
- Marfan Syndrome (see Marfan Syndrome)
Hypertension (see Hypertension)
- Crack Cocaine (see Cocaine)
- Energy Drinks
- Ergotism (see Ergotism)
- Methamphetamine Intoxication (see Methamphetamine)
Pre-Existing Aortic Aneurysm (see Thoracic Aortic Aneurysm)
Pregnancy/Delivery (see Pregnancy)
- Risk is Compounded by Presence of Marian Syndrome and Bicuspid Aortic Valve
Turner Syndrome
Trauma
- Rare Etiology of Aortic Dissection: deceleration injuries more commonly cause aortic rupture or transection
- Can Cause a Localized Tear in the Area of the Aortic Isthmus
Vasculitis
- Temporal (Giant Cell) Arteritis (see Temporal Arteritis)
- Rheumatoid Arthritis (RA) (see Rheumatoid Arthritis)
- Syphilitic Aortitis (see Syphilis)
- Takayasu’s Arteritis (see Takayasu’s Arteritis)

Physiology

Site of Involvement

Ascending Aortic Dissection is Almost Twice as Common as Descending Aortic Dissection
- Right Lateral Wall of the Ascending Aorta is the Most Common Site of Aortic Dissection (Am J Cardiol, 1984) [MEDLINE]
- In the Presence of Ascending Aortic Dissection, Aortic Arch Involvement Occurs in 30% of Cases (Circulation, 2003) [MEDLINE]

Diagnosis

Chest X-Ray (see Chest X-Ray)

Findings
- Widened Mediastinum
Clinical Data
- Chest X-Ray was Abnormal in 87.6% of Cases (JAMA, 2000) [MEDLINE]

Electrocardiogram (EKG) (see Electrocardiogram)

Clinical Data
- EKG was Abnormal in Only 68.7% of Cases (JAMA, 2000) [MEDLINE]

Plasma D-Dimer (see Plasma D-Dimer)

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Aortogram (see Aortogram)

Classical Procedure (Since the 1960’s) to Diagnose Aortic Dissection: not routinely used due to availability of other methods

Transesophageal Echocardiogram (TEE) (see Echocardiogram)

Technique

Advantages
- Ability to Diagnose Aortic Insufficiency

Clinical Efficacy

Systematic Review and Meta-Analysis Examining the Diagnostic Accuracy of Transesophageal Echocardiogram, Helical CT, and MRI Imaging for the Diagnosis of Thoracic Aortic Dissection (Arch Intern Med, 2006) [MEDLINE]
- Transesophageal Echocardiogram, Helical CT, and MRI Imaging All Yield Clinically Equally Reliable Diagnosis of Thoracic Aortic Dissection

CT Aortic Angiogram (see Chest Computed Tomography)

Technique

CT is the Most Commonly Utilized Initial Diagnostic Modality (JAMA, 2000) [MEDLINE]: used in 61.1% of cases
Sensitivity/Specificity for the Diagnosis of Aortic Dissection: 83-95%/87-100%
Accuracy of CT Aortic Angiogram is Improved with Spiral (Helical) CT and Possibly Multidetector (Multislice) CT
Disadvantages
- Intimal Flap is Identified in <75% of Cases: diagnosis requires the identification of two distinct lumens
- Site of Entry is Rarely Identified
- Requirement for Nephrotoxic Intravenous Contrast
- No Ability to Diagnose Aortic Insufficiency

Clinical Efficacy

Systematic Review and Meta-Analysis Examining the Diagnostic Accuracy of Transesophageal Echocardiogram, Helical CT, and MRI Imaging for the Diagnosis of Thoracic Aortic Dissection (Arch Intern Med, 2006) [MEDLINE]
- Transesophageal Echocardiogram, Helical CT, and MRI Imaging All Yield Clinically Equally Reliable Diagnosis of Thoracic Aortic Dissection

MR Aortic Angiogram (see Magnetic Resonance Aortic Angiogram)

Clinical Efficacy

Systematic Review and Meta-Analysis Examining the Diagnostic Accuracy of Transesophageal Echocardiogram, Helical CT, and MRI Imaging for the Diagnosis of Thoracic Aortic Dissection (Arch Intern Med, 2006) [MEDLINE]
- Transesophageal Echocardiogram, Helical CT, and MRI Imaging All Yield Clinically Equally Reliable Diagnosis of Thoracic Aortic Dissection

Clinical Manifestations

General Comments

Clinical Classification Schema

Stanford System
- Type A: involves the ascending aorta
  - May Progress to Involve the Aortic Arch and Thoracoabdominal aorta
- Type B: involves the descending aorta or thoracoabdominal aorta distal to the left subclavian artery without involvement of the ascending aorta
Debakey System
- Type I: involves the ascending aorta, arch, and descending thoracic aorta
  - May Progress to Involve the Abdominal aorta
- Type II: confined to the ascending aorta
- Type IIIa: involves the descending thoracic aorta distal to the left subclavian artery and proximal to the celiac artery
- Type IIIb: involves the thoracic and abdominal aorta distal to the left subclavian artery
DISSECT Classification (Eur J Vasc Endovasc Surg, 2013) [MEDLINE]
- Accounts for 6 Clinical Features of Aortic Dissection
  - Clinical Complications of the Dissection
  - Duration of Disease
  - Intimal Tear Location
  - Segmental Extent of Aortic Involvement
  - Size of the Dissected Aorta
  - Thrombus within the Aortic False Lumen

Duration of Symptoms

During the First 2 wks (Acute Phase), Life-Threatening Complications (Aortic Rupture, Branch Involvement, etc) are More Likely to Occur than During the Timeframe After 2 wks (Chronic Phase) (JAMA, 1990) [MEDLINE]

Cardiovascular Manifestations

Aortic Insufficiency (AI) (see Aortic Insufficiency)
- Physiology: due to progression of the aortic dissection into the aortic valve
- Clinical
  - Severe Aortic Insufficiency May Occur Acutely: present in only 31.6% of cases (JAMA, 2000) [MEDLINE]
Chest Pain/Back Pain (see Chest Pain and Back Pain)
- Physiology
  - Aortic Dissection Itself
  - Obstruction of the Coronary Ostia with Myocardial Ischemia/Infarction
- Clinical
  - Sudden Onset of Severe Sharp Chest Pain: most common single presenting complaint (JAMA, 2000) [MEDLINE]
Hemopericardium/Tamponade (see Hemopericardium and Tamponade)
- Physiology: due to rupture of aortic dissection into the pericardium
- Clinical
  - Hypotension (see Hypotension)
- Hypotension (see Hypotension)
- Etiologic Mechanisms
  - Acute Aortic Insufficiency (AI) (see Aortic Insufficiency)
  - Hemoperitoneum (see Hemoperitoneum)
  - Hemothorax (see Pleural Effusion-Hemothorax)
  - Myocardial Infarction (MI) (see Coronary Artery Disease)
  - Tamponade (see Tamponade)
Myocardial Infarction (MI) (see Coronary Artery Disease)
- Physiology: due to obstruction of the coronary ostia
- Clinical
  - Chest Pain (see Chest Pain)
Syncope (see Syncope)
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Gastrointestinal Manifestations

Colonic Ischemia (Ischemic Colitis) (see Colonic Ischemia)

Neurologic Manifestations

Focal Neurologic Deficits
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Renal Manifestations

Acute Kidney Injury (AKI) (see Acute Kidney Injury)
- Physiology: due to compromise of renal artery blood flow

Vascular Manifestations

Pulse Deficit
- Physiology: due to intimal flap or compression by hematoma
- Clinical
  - Impaired/Absent Carotid/Brachial/Femoral Pulses: present in only 15.1% of cases (JAMA, 2000) [MEDLINE]
  - Discrepancy in Blood Pressures (>20 mm Hg) Between the Arms (or Legs)

Treatment

Ascending (Type A) Aortic Dissection

Medical Management
- Blood Pressure Management
Surgery
- Type A Dissection is a Surgical Emergency: due to reported mortality rate of 1-2% per hour early after symptom onset without surgical Intervention (Circulation, 2003) [MEDLINE]
Endovascular Repair (see Aortic Endograft)
- Limited Experience
- May Be Useful in Patients with Ischemic Complications
Hybrid Approach (“Frozen Elephant Trunk Repair”)
- Open Surgical Repair of Ascending Aorta + Aortic Endograft for Descending Aorta

Descending (Type B) Aortic Dissection

Medical Management: recommended initial approach for type B dissection
- Blood Pressure Management
- Imaging Surveillance
Surgery
- May Be Required for Rare Cases of Type B Aortic Dissection Which are Not Amenable to Aortic Endograft or Cases Which are Genetically-Mediated
Endovascular Repair (see Aortic Endograft)
- Thoracic Endovascular Aortic Repair (TEVAR) Has Been Used Instead of Surgery for Type B Aortic Dissection*
Clinical Efficacy
- International Registry of Aortic Dissection (IRAD) Database of Outcome in Medically-Managed Type B Dissection (Circulation, 2003) [MEDLINE]
  - In-Hospital Mortality Rate: 10%
- INvestigation of STEnt Grafts in Patients with Aortic Dissection (INSTEAD) Trial in Uncomplicated Type B Dissection (Circulation, 2009) [MEDLINE]: randomized trial (n = 140)
  - Thoracic Endovascular Aortic Repair (TEVAR) Failed to Improve 2-Year Survival and Adverse Event Rates, as Compared to Medical Management
- INSTEAD-XL Trial Examining Long-Term F/U After TEVAR (Circ Cardiovasc Interv, 2013)
  - Endovascular Treatment was Associated with Favorable Aorta-Specific Mortality Rate, as Compared to Medical Management Alone

Prognosis

In-Hospital Mortality Rate: 27.4% (JAMA, 2000) [MEDLINE]
- Type A Dissection
  - Managed Surgically: 26%
  - Not Managed Surgically (Usually Due to Advanced Age or Comorbidity): 58%
- Type B Dissection
  - Managed Surgically (Surgery was Performed in 20% of Patients with Type B Dissection): 31.4%
  - Not Managed Surgically: 10.7%
Mortality Rate of 1-2% Per Hour Early After Symptom Onset without Surgical Intervention in Type A Dissection (Circulation, 2003) [MEDLINE]
Predictors of Death in Aortic Dissection (Circulation, 2002) [MEDLINE]
- Age ≥70 y/o (OR, 1.70; 95% CI, 1.05 to 2.77; P=0.03)
- Abnormal EKG (OR, 1.77; 95% CI, 1.06 to 2.95; P=0.03)
- Abrupt Onset of Chest Pain (OR 2.60; 95% CI, 1.22 to 5.54; P=0.01)
- Hypotension/Shock/Tamponade (OR, 2.97; 95% CI, 1.83 to 4.81; P<0.0001)
- Kidney Failure (OR, 4.77; 95% CI, 1.80 to 12.6; P=0.002)
- Pulse Deficit (OR, 2.03; 95% CI, 1.25 to 3.29, P=0.004)

References

Risk factors for aortic dissection: a necropsy study of 161 cases. Am J Cardiol. 1984;53(6):849 [MEDLINE]
The diagnosis and management of aortic dissection. JAMA. 1990;264(19):2537 [MEDLINE]
The International Registry of Acute Aortic Dissection (IRAD): new insights into an old disease. JAMA. 2000;283(7):897 [MEDLINE]
Diagnosis and management of aortic dissection. Eur Heart J. 2001 Sep;22(18):1642-81 [MEDLINE]
Predicting death in patients with acute type a aortic dissection. Circulation. 2002;105(2):200 [MEDLINE]
Surgical treatment of complicated distal aortic dissection. Semin Vasc Surg. 2002;15(2):97 [MEDLINE]
Clinical profiles and outcomes of acute type B aortic dissection in the current era: lessons from the International Registry of Aortic Dissection (IRAD). Circulation. 2003;108 Suppl 1:II312 [MEDLINE]
Aortic dissection: new frontiers in diagnosis and management: Part II: therapeutic management and follow-up. Circulation. 2003;108(6):772 [MEDLINE]
Thoracic aortic aneurysms. Acta Chir Belg. 2006 May-Jun;106(3):307-16 [MEDLINE]
Diagnostic accuracy of transesophageal echocardiography, helical computed tomography, and magnetic resonance imaging for suspected thoracic aortic dissection: systematic review and meta-analysis. Arch Intern Med. 2006 Jul 10;166(13):1350-6 [MEDLINE]
Aortic dissection: perspectives in the era of stent-graft repair. J Vasc Surg. 2006;43 Suppl A:30A [MEDLINE]
The aortic arch and ascending aorta: are they within the endovascular realm? Semin Vasc Surg. 2007 Jun;20(2):97-107 [MEDLINE]
Etiology, pathogenesis and management of thoracic aortic aneurysm. Nat Clin Pract Cardiovasc Med. 2007 Aug;4(8):418-27 [MEDLINE]
Randomized comparison of strategies for type B aortic dissection: the INvestigation of STEnt Grafts in Aortic Dissection (INSTEAD) trial. Circulation. 2009;120(25):2519. Epub 2009 Dec 7 [MEDLINE]
DISSECT: a new mnemonic-based approach to the categorization of aortic dissection. Eur J Vasc Endovasc Surg. 2013 Aug;46(2):175-90. Epub 2013 May 28 [MEDLINE]
INSTEAD-XL Trial. Endovascular repair of type B aortic dissection: long-term results of the randomized investigation of stent grafts in aortic dissection trial. Circ Cardiovasc Interv. 2013 Aug;6(4):407-16. Epub 2013 Aug 6