Aortic Dissection

Aortic Dissection

Information for Patients from the International Registry of Acute Aortic Dissection

What Happens During an Aortic Dissection?

An aortic dissection is a tear in the wall of the aorta that allows blood to flow within the layers of the aorta. Early diagnosis and treatment of this illness is critical for survival. Certain types (Type A) of dissections, if left untreated, kill 33% of patients within the first 24 hours, 50% of patients within 48 hours, and 75% of patients within 2 weeks.

What is the aorta?

The aorta is the main vessel that sends blood away from the heart to the rest of the body. It is shaped like a candy cane and is about as wide as a garden hose (2.5-3.5 cm). When blood is pumped by the heart, it first travels through the aorta. Similar to a plumbing system, blood is then delivered through connecting vessels to the rest of the body.

Figure 1: the Aorta
aorta

The wall of the aorta consists of 3 layers: the intima, media, and adventitia. The intima is the innermost layer; the media, the middle layer; the adventitia, the outer later. These layers are shown in Figure 2.

Figure 2: LAYERS OF THE AORTIC Wall
layers of the aortic wall

What is an aortic dissection?

A dissection occurs when a tear of the intima (the inner lining) allows blood to leak into the media (middle layer). This creates two passages for blood: a true lumen, which is the normal passageway of blood, and a false lumen, the newly created passageway. A normal aorta and a dissected aorta are shown in Figure 3.

Figure 3: Normal Aorta and Dissected Aorta
Normal and Dissected Aorta

What problems do dissections cause?

As blood flows into the false lumen, the false lumen may enlarge and block blood flow into the true lumen. The false lumen may also divert blood flow away from the true lumen. In addition, after an initial tear causes a dissection, the dissection may spread and involve branching vessels, valves, or even the sac surrounding the heart. Multiple tears may even form as a result of the initial tear.

The end result of an aortic dissection is that the amount of oxygen and nutrients available for organs of the body is decreased. As can be seen in Figure 4, the aorta is in close proximity to many organs. The brain, kidneys, intestines, heart, and even the arms and legs may be affected by an aortic dissection.

For example, the following organs can be involved:

  • Brain: if the common carotid arteries are involved
  • Kidneys: if the renal arteries are involved

Figure 4: Major vessels from the aorta
vessels of the aorta

How often do dissections occur?:

Approximately 2000 new cases are reported every year in the United States. It is a rare but serious condition that mostly occurs in men aged 60 to 80. However, the male-to-female ratio is 3:1 and aortic dissections do occur in young people, especially those with risk factors.

What puts a person at risk?

The following risk factors have been associated with aortic dissections. Please see the Glossary for more information about many of the conditions listed below.

  • Hypertension – the most important predisposing risk factor. In research published by IRAD, hypertension has been associated in over 70% of patients.
  • Preexisting aortic aneurysm – more common cause in patients under age 40
  • Connective Tissue Disorders
    • Marfan syndrome
    • Ehlers-Danlos syndrome
  • Inflammatory diseases that cause a vasculitis (disease that causes damage to blood vessels)
    • Giant cell arteritis
    • Takayasu arteritis
    • Rheumatoid arthritis
    • Syphilitic aortitis
  • Bicuspid aortic valve – a congenital anatomic abnormality
  • Turner syndrome
  • Coronary Artery Bypass Graft surgery – dissection is a rare complication of this surgery
  • Cardiac catheterization – a rare complication of this procedure
  • High-intensity weight lifting – during significant weight training a patient’s blood pressure may increase significantly. Especially in patients with risk factors or family history of aneurysms, strenuous weight lifting can be extremely dangerous.
  • Family history – first degree relatives with history of aneurysms or dissections
  • Crack cocaine – average time between last cocaine use and dissection was 12 hours

How are dissections classified?

Physicians divide the aorta into 3 sections: the ascending aorta, the descending aorta, and the abdominal aorta. These divisions are shown in Figure 5. A dissection may occur anywhere along this path.

Figure 5: Divisions of the aorta
Divisions of the aorta

Aortic dissections are classified by physicians based on where the tear in the inner lining occurred. The 2 most common classification systems are the DeBakey and Stanford classification system. Depending on where in the aorta a dissection occurs, the treatment may range from medications to surgery.

  • DeBakey Classification:
    • Type I – originated in ascending aorta
    • Type II – originated in and is confined to ascending aorta
    • Type III – originated in descending aorta
  • Stanford Classification system
    • A – Originated and involves ascending aorta.
    • B – Originated and involves descending aorta

Figure 6: Type A and Type B Dissections

Key Points

  • Aortic Dissections are caused by a tear in the intimal layer, allowing blood to leak into the middle medial layer.
  • Depending on where the tear occurs and how far it spreads, the brain, kidneys, heart, arms, or legs could be affected.
  • Most dissections are associated with hypertension or connective tissue disorders.
  • Dissections are classified by where the tear originated.
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3 gedachtes over “Aortic Dissection

  1. JAMA. 2000 Feb 16;283(7):897-903.
    The International Registry of Acute Aortic Dissection (IRAD): new insights into an old disease.
    Hagan PG, Nienaber CA, Isselbacher EM, Bruckman D, Karavite DJ, Russman PL, Evangelista A, Fattori R, Suzuki T, Oh JK, Moore AG, Malouf JF, Pape LA, Gaca C, Sechtem U, Lenferink S, Deutsch HJ, Diedrichs H, Marcos y Robles J, Llovet A, Gilon D, Das SK, Armstrong WF, Deeb GM, Eagle KA.
    Source

    University of Michigan, Ann Arbor, USA.
    Abstract
    CONTEXT:

    Acute aortic dissection is a life-threatening medical emergency associated with high rates of morbidity and mortality. Data are limited regarding the effect of recent imaging and therapeutic advances on patient care and outcomes in this setting.
    OBJECTIVE:

    To assess the presentation, management, and outcomes of acute aortic dissection.
    DESIGN:

    Case series with patients enrolled between January 1996 and December 1998. Data were collected at presentation and by physician review of hospital records.
    SETTING:

    The International Registry of Acute Aortic Dissection, consisting of 12 international referral centers.
    PARTICIPANTS:

    A total of 464 patients (mean age, 63 years; 65.3% male), 62.3% of whom had type A dissection.
    MAIN OUTCOME MEASURES:

    Presenting history, physical findings, management, and mortality, as assessed by history and physician review of hospital records.
    RESULTS:

    While sudden onset of severe sharp pain was the single most common presenting complaint, the clinical presentation was diverse. Classic physical findings such as aortic regurgitation and pulse deficit were noted in only 31.6% and 15.1% of patients, respectively, and initial chest radiograph and electrocardiogram were frequently not helpful (no abnormalities were noted in 12.4% and 31.3% of patients, respectively). Computed tomography was the initial imaging modality used in 61.1%. Overall in-hospital mortality was 27.4%. Mortality of patients with type A dissection managed surgically was 26%; among those not receiving surgery (typically because of advanced age and comorbidity), mortality was 58%. Mortality of patients with type B dissection treated medically was 10.7%. Surgery was performed in 20% of patients with type B dissection; mortality in this group was 31.4%.
    CONCLUSIONS:

    Acute aortic dissection presents with a wide range of manifestations, and classic findings are often absent. A high clinical index of suspicion is necessary. Despite recent advances, in-hospital mortality rates remain high. Our data support the need for continued improvement in prevention, diagnosis, and management of acute aortic dissection.

    From:
    http://www.ncbi.nlm.nih.gov/pubmed/10685714

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