Chapter30 Aorta

Thoracic Aorta

Chapter 30 n

KATHLEEN JACOBS, MICHAEL J. HOROWITZ, and SETH KLIGERMAN

Aortic Root Anatomy and Variants Aortic Valve Ascending Aorta Aortic Arch Anatomy and Variants Left Arch Variants Right Arch Variants Double Aortic Arch Cervical Aortic Arch Interrupted Aortic Arch Circumflex Aorta Descending Thoracic Aorta Aortic Coarctation Pseudocoarctation Atheroma Aneurysm Sinus of Valsalva Aneurysm

Ascending Thoracic Aorta and Aortic Arch Aneurysms Descending Thoracic Aortic Aneurysms Acute Aortic Syndrome Aortic Dissection Intramural Hematoma Penetrating Atherosclerotic Ulcer Aortic Pseudoaneurysm Aortic Fistulas Acute Traumatic Aortic Injury Postoperative Aorta Complications Thoracic Endovascular Aortic Repair Aortitis Aortic Tumors Conclusion

The thoracic aorta is a tubular, candy-cane–shaped structure that connects the left ventricle to the systemic circulation. It extends from the level of the aortic valve to the diaphragmatic hiatus where it transitions to the abdominal aorta, approxi- mately at the level of T12. The thoracic aorta is anatomically divided into the aortic root, ascending aorta, transverse arch, and descending thoracic aorta (Fig. 30.1).

posteriorly between the right and left atria. Above the sinuses of Valsalva is the sinotubular junction, which is an anatomic waist between the sinuses of Valsalva and tubular ascending aorta. Dimensions of the aorta vary with age, gender, and body size in adults. The aorta is generally largest in diameter at the sinuses of Valsalva and progressively tapers distally. Reported normal diameter of the aortic root is 3.5 to 3.72 cm in females and 3.63 to 3.91 cm in males on CT, measured orthogonal to the aorta. Aortic Valve The aortic valve serves as both a physical and hemodynamic boundary between the left ventricle and aorta. The normal aor- tic valve is composed of three leaflets/cusps which insert into the annular ring and coapt and form a trileaflet valve plane just inferior to the sinuses of Valsalva (Fig. 30.2). The contact points between valve leaflets are termed the valve commissures, which are best visualized during end diastole when the aortic valve is closed. Congenital anomalies of the aortic valve are not uncom- mon and include unicuspid, bicuspid, or quadricuspid valve morphologies. Bicuspid aortic valve is the most common con- genital cardiovascular anomaly with a prevalence of 0.5% to 2%. There are two major morphologic types of bicuspid aortic valve. A true bicuspid valve with completely separate and sym- metric valves without a fused raphe is less frequent, compris- ing approximately 7% of bicuspid aortic valves (Fig. 30.3).

Aortic Root Anatomy and Variants

The aortic root extends from the aortic annular ring to the sinotubular junction. The aortic valve annulus is a fibrous oval ring where the leaflets of the aortic valve attach and extend superiorly toward the sinuses of Valsalva. The aortic annulus is coupled to the mitral annulus via aortomitral fibrous tissue, which is a defining feature of the left ventricle. This is in con- tradistinction to the pulmonary valve, which is supported by the muscular right ventricular outflow tract. Superior to the annulus are the sinuses of Valsalva which are three anatomic bulges of the aorta (Fig. 30.2). The three leaflets of the aortic valve form the valve plane at the level of the sinuses. The coronary artery ostia arise from the sinuses of Valsalva above the valve plane but below the sinotubular junction. The sinuses are named based on their respective cor- onary artery. The right coronary artery (RCA) arises from the right sinus of Valsalva which is directed anteriorly, and the left main coronary artery arises from the leftward facing left sinus of Valsalva. The noncoronary sinus is usually directed

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