OTHER VASCULAR DISORDERS

David Goldemund M.D.
Updated on 07/11/2023, published on 05/05/2023

• the aorta is the main artery of the human body, divided by the diaphragm into the thoracic and abdominal segments
• in healthy adults, the aorta is usually less than 40 mm in diameter and gradually narrows downwards
  • aorta increases its diameter by approx. 0.9 mm in men and 0.7 mm in women every 10 years
    
• aortic dissection is characterized by a tear in the intimal layer of the aorta, allowing blood to enter and dissect the layers of the wall
• a relatively rare disorder with a high mortality rate; it is the most common form of acute aortic syndrome (AAS)
  • AAS = a group of aortic emergencies with similar clinical characteristics, including intramural hematoma, penetrating aortic ulceration, dissection, and rupture
• aortic dissection remains one of the few absolute contraindications to intravenous thrombolysis

• an intimal tear (or ulcer penetration) leads to bleeding into the medial layer of the aortic wall, subsequently forming a true and false lumen 
  • the true lumen is lined by the intima; the false lumen is a blood-filled channel within the medial layer
  • the process may be followed by aortic rupture or reentry into the true lumen via a secondary intimal tear (reentry point)
• main complications:
  • cardiac tamponade
  • aortic regurgitation
  • proximal or distal malperfusion syndromes (periphery, CNS)
• classifications
  • DeBakey
    • type I – begins in the ascending aorta and extends to the abdominal segment
    • type II – dissection is limited to the ascending aorta
    • type III – dissection originates in the aortic isthmus and involves the descending aorta, potentially extending to the abdominal segment
  • Stanford classification
    • type A – the ascending aorta is affected (twice as common as type B)  (∼ 60%)
    • type B – the descending aorta is affected
  • classification based on timing
    • acute: ≤ 14 days from symptom onset
    • subacute:  14 days – 3 months
    • chronic: > 3 months from symptom onset
  • communicating x non-communicating
  • DISSECT classification (Duration, Intimal tear, Size of the dissected aorta, Segmental extent of involvement, Clinical complications, Thrombosis of the false lumen)

• a complication of an underlying inherited connective tissue disorder
  • Marfan syndrome
  • Ehlers-Danlos syndrome
  • Loeys-Dietz syndrome
• idiopathic  (with some known predisposing factors)
  • atherosclerosis (penetrating ulcer)
  • hypertension (medial degeneration)
  • vasculitis
  • structural aortic abnormalities (bicuspid aortic valve, aortic coarctation)
  • pregnancy
  • previous intervention (cardiac or aortic surgery, intra-aortic balloon pump)
  • use of fluoroquinolones

• incidence 6/100,000/year
• typically occurs in elderly hypertensive patients; higher incidence in men than in women
• up to 38% of cases remain undiagnosed at the initial examination
• prognosis is worse in women due to atypical symptoms and delayed diagnosis

• chest pain (70-80%) or back pain (more common in type B)
  • the most typical symptom; however, about 6% of patients are completely pain-free
  • sudden onset of severe, shooting pain in the chest and/or back
  • sometimes intermittent or migrating
• aortic regurgitation (40-70%) – dissection leads to dilatation of the aortic root and aortic annulus, tearing of the aortic cusps;  a diastolic murmur over the aorta is clinically present
• hypotension or signs of shock (25% of patients)
  • may result from aortic rupture, acute significant aortic regurgitation, massive myocardial infarction, cardiac tamponade, or major blood loss
• myocardial ischemia (10-15%)
• congestive heart failure
• syncope (type A 15%, type B < 5%)
• evidence of malperfusion (depending on the extent of dissection and occlusion of aortic branches)
  • neurologic symptoms
    • stroke (< 5-10%)
    • spinal ischemia (< 1%) due to involvement of the artery of Adamkiewicz
  • abdominal ischemia (mesenteric artery)
  • limb ischemia (different BP in upper and lower extremities, weak pulsations)
  • renal failure – 20% of patients with acute type A and approx. 10% of patients with type B

• diagnostic procedures aim to confirm or exclude dissection; their choice depends on the risk assessed by the medical history and clinical presentation (ADD-RS)
• D-dimer testing is advised only in stable, low-risk patients (not recommended in cases with a high clinical probability of aortic dissection)
  • with a low clinical probability of AAS, negative D-dimers should be considered as an exclusion of AAS
  • intermediate clinical probability of AAS together with a positive D-dimer result warrants further imaging studies
    
• transthoracic echocardiography (TTE) is recommended as the initial imaging, followed by:
  • computed tomography (CT) or transesophageal echocardiography (TEE) in unstable patients
  • CT, TEE, or MRI in stable patients
• if initial imaging is negative, reimaging (CT/MR) is recommended if AAS is still suspected
• for uncomplicated type B dissection managed conservatively, reimaging (CT/MR) within 24 hours is recommended

• pseudodissection caused by the aortic pulsations (use ECG-gated CTA to avoid this motion artifact)
• “pseudo flap” appearance on some MRI sequences (due to susceptibility artifact)
• mural thrombus
• intramural hematoma, penetrating atherosclerotic ulcer (both part of an acute aortic syndrome)

• pharmacotherapy for pain control and blood pressure optimization is recommended for all patients with aortic dissection (ESC 2014 I/C)
  • target SBP < 100-120 mm Hg
  • target HR < 60/min
  • beta-blockers are preferred
• urgent surgical treatment is recommended for patients with aortic dissection type A  (ESC 2014 I/B)
• in patients with type A + malperfusion, a hybrid approach should be considered (i.e., replacement of the ascending aorta and/or aortic arch combined with any percutaneous intervention on the aorta or outflowing arteries)  (ESC 2014 IIa/B)
• in patients with uncomplicated type B dissection, pharmacotherapy is recommended (ESC 2014 I/C)
• consider TEVAR (thoracic endovascular aortic repair) in patients with uncomplicated type B (ESC 2014 IIa/B)
• TEVAR is recommended in patients with complicated type B (ESC 2014 I/C)
• surgical treatment may be considered in patients with complicated type B (ESC 2014 IIb/C)

Type A and B

• malperfusion due to:
  • dissection with stenosis/occlusion of aortic branches
  • distal thromboembolism
• aneurysmal dilatation
• aortic rupture
• hemothorax

Stanford type A  specific complications

• coronary artery occlusion with MI
• aortic incompetence
• aortic valve insufficiency
• hemopericardium with cardiac tamponade
• hemorrhagic shock