Cardiac vascular connections, anatomy, and ultrasound imaging: Major Blood Vessels Encountered During Routine Echocardiography

Aorta

It arises from the left ventricle and is divided into the aortic root, tubular ascending aorta, aortic arch, descending thoracic aorta, and abdominal aorta ( Fig. 2.1 ). All these aortic segments are assessed during routine echocardiography.

The tubular ascending aorta comprises of a proximal portion, from the sinotubular junction to the pulmonary artery level, and a distal portion, from the pulmonary artery to the origin of the brachiocephalic artery ( Fig. 2.1 ). The aortic arch gives rise to three major branches, the brachiocephalic or innominate artery, the left common carotid artery, and the left subclavian artery; and then continues as the descending thoracic aorta ( Fig. 2.1 ). The aortic arch is the segment between the brachiocephalic artery and the left subclavian artery. Below the diaphragm, the aorta continues as the abdominal aorta.

The descending thoracic aorta has a proximal segment, from the left subclavian artery to the pulmonary artery, and a distal segment, from the pulmonary artery to the diaphragm ( Fig. 2.1 ). The abdominal aorta is divided into a proximal segment, from the diaphragm to the renal arteries (suprarenal aorta), and a distal segment, from the renal arteries to the iliac bifurcation (infrarenal segment) ( Fig. 2.1 ).

The celiac and superior mesenteric arteries that supply blood to the stomach, spleen, pancreas, and intestines arise from the suprarenal aorta and the inferior mesenteric artery that supplies the kidneys and lower portion of the intestines arises from the infrarenal aorta. The aorta then divides into the two common iliac arteries. The external iliac artery continues below the origin of the left and right renal arteries as the femoral artery on either side and supplies blood to the lower extremities. The presence of an aortic aneurysm can be evaluated during routine echocardiography and are most commonly located in the infrarenal portion of the abdominal aorta.

Ultrasound imaging of cardiac vascular connections

Aorta

Ultrasound imaging of the aorta is performed using various imaging windows along its course ( Fig. 2.2 ). The aortic root and ascending aorta are readily visualized during routine parasternal imaging ( Fig. 2.3 ). The aortic root comprises of the aortic annulus, aortic valve, aortic sinuses, and sinotubular junction. The ascending aorta often requires a higher imaging window (one or two intercostal spaces higher) than the aortic root; otherwise, enlargement of this segment of the aorta can be missed ( Fig. 2.4 ). The aortic root and ascending aorta should also be visualized from the right parasternal window when an aortic root, ascending aorta, or aortic valve pathology is suspected ( Fig. 2.5 ). The aortic arch and proximal descending thoracic aorta are visualized from the sternal notch at the base of the neck ( Fig. 2.6 ).

Aortic dimensions are routinely measured at the aortic sinuses and ascending aorta. The mid portion of the descending thoracic aorta can be routinely visualized posterior to the LA in the parasternal long axis (PLAX) view ( Fig. 2.3 ) and lateral to the LA in the apical 4-chamber view. The distal portion of the descending aorta can be visualized in the off-axis 2-chamber view.

The abdominal aorta lies posterior and to the left of the inferior vena cava and is imaged from the subcostal window in the short- and long-axis views and is able to demonstrate normal anatomy ( Fig. 2.7 ), aortic enlargement, aortic dissection flap, and aortic atheroma ( Fig. 2.8 ).