Aortic Dissection Overview

Aortic dissection is defined as a tear in the aortic intima through which blood enters the aortic wall, consequently destroying the media and stripping the intima from the adventitia.

Type 1 (70%): Involvement of the ascending, transverse, and descending aorta; includes Types 2 and 3.
Type 2 (5%): Dissection involving the ascending aorta, stopping proximal to the brachiocephalic artery.
Type 3 (25%): Dissection confined to the descending thoracic aorta, often extending into the abdominal aorta.
Note: Type 2 + Type 3 = Type 1.

Type A: All dissections that involve the ascending aorta (including DeBakey types 1 and 2).
Type B: All dissections that do not include the ascending aorta (DeBakey Type 3).

Systemic Hypertension: A key risk factor for development.
Arterial Disease: Includes atherosclerosis, and is more prevalent in certain congenital conditions.
Genetic Factors:
- Bicuspid aortic valve: Associated with a ninefold increase in risk of dissection compared to trileaflet aortic valve.
- Marfan syndrome.
- Ehlers-Danlos syndrome.
- Loeys-Dietz syndrome.
Congenital Factors: Conditions like aortic coarctation, Turner syndrome, and Tetralogy of Fallot are linked to a higher risk.
Trauma: Can occur due to catheter or stent insertion, intraaortic balloon pumps, or motor vehicle accidents.
Miscellaneous Factors: Includes giant cell arteritis, Takayasu arteritis, Behcet disease, syphilis, pregnancy, cocaine use, aging, strenuous physical exertion, discontinuation of beta blockers, and renal disease.

Clinical Features:
- Systemic hypertension and congenital heart disease, like bicuspid aortic valve.
- Severe chest pain often described as "tearing," radiating to the back or abdomen (90% of cases).
- Myocardial ischemia/infarction (10%).
- Heart failure symptoms (dyspnea, orthopnea, paroxysmal nocturnal dyspnea, fatigue, cough, weight gain) found in 7% of cases.
- Neurological symptoms, such as syncope (13%) and cerebral vascular accident (6%).
Physical Exam Signs:
- Pulse deficits.
- Elevated jugular venous pressure.
- Brisk arterial pulse.
- Pericardial friction rub.

Major systemic artery occlusions (carotid, coronary, renal).
Heart failure or cardiogenic shock, potentially leading to death from hemopericardium or rupture.

May show:
- Lack of changes despite severe chest pain.
- Left ventricular hypertrophy (25% of cases).
- Signs of myocardial ischemia/infarction, usually involving the inferior wall.

Chest X-ray/CMR/CT Findings:
- Widening of the aortic silhouette (90%).
- Signs of cardiomegaly and possible pleural effusion (usually on the left in 20%).
- CT with contrast to assess the intimal flap, the two lumens, involvement of aortic branches, and presence of thrombus in the false lumen.
- CMR is valuable for determining the extent of the dissection and branch vessel involvement.
Cardiac Catheterization:
- Angiogram to visualize true and false aortic lumens, compromised arteries, and assess ventricular function and valvular issues.

Focus on managing systemic hypertension.
Close follow-up for high-risk patients (e.g., those with Marfan's syndrome, Ehlers-Danlos).
Medications:
- Morphine for pain management.
- Sodium nitroprusside for blood pressure control.
- Intravenous propranolol/labetalol for heart rate and blood pressure management.
Medical therapy may suffice for dissections localized to the descending thoracic aorta.

May include:
- Transection of ascending aorta, with resection of the intimal tear and use of Dacron grafts for reconnection.
- Endoluminal grafts (ELG) or stenting.

2D Imaging: Require comprehensive views to visualize the entire aorta, including several standard positions (parasternal, apical, subcostal, and suprasternal views).
Key Findings:
- Presence of intimal flap (demonstrated in multiple views).
- Compression of the false lumen during ventricular systole.
- Spontaneous echo contrast and thrombus in the false lumen.
- Assessment and management of cardiac structures like the left atrium and potential pericardial effusion.
Doppler Evaluation: Assess forward flow in true lumen and reverse or absent flow in false lumen, presence of aortic/mital regurgitation, and cardiac tamponade based on flow variations.

Evaluate potential complications such as recurring aortic disease, presence of intimal flaps, and performance of valves.
Follow-up for organ blood flow and adequacy of repairs (like that of the aortic valve).

Acute aortic syndrome encompasses aortic dissection, intramural hematoma, penetrating aortic ulcer, atherosclerotic plaque rupture, and aneurysm rupture.
Intramural hematoma constitutes 5-10% of aortic dissections.
Surgical intervention is often recommended for DeBakey types I and II dissections.
Differentiation between true lumen and false lumen is crucial for management, with the true lumen usually presenting smaller, expanding in systole, having a more regular shape, and not containing spontaneous echo contrast or thrombus.