AE 1.8 - Great Vessels

Aortic wall (layers & functions)

intima

• thin, inner lining

• smooth layer for blood flow

media

• thick, middle muscle layer

• for constriction & dilation

• pulsatile flow

adventitia

• outer layer

• anchor, connect, & support aorta

Major segments of the thoracic aorta

aortic root

ascending aorta

aortic arch

descending aorta

Branches of the aortic arch

innominate artery

• right subclavian

• right common carotid

left common carotid

left subclavian

Basic function of the aorta as a conduit & reservoir

conduit

• high flow of oxygen rich blood to whole body

• blood from LV —> systemic circuit of arteries

reservoir

• acts as elastic buffer, propels blood forward

• expands during systole —> store large part of SV

• recoils during diastole —> to maintain continuous blood flow

Standard echocardiographic windows used to evaluate each portion of the aorta

PLAX & PSAX

• ascending aorta

• descending aorta

Apicals (4, 2, long axis)

• descending thoracic aorta

Subcostal

• abdominal aorta

Suprasternal

• ascending, arch, descending aorta

Right sternal border

• ascending aorta (more distal)

Advantages & limitations of TTE for assessing the aorta

advantages

• quick

• portable

• non invasive

• can see aortic root well

limitations

• sensitivity not sufficient distal to aortic root

• descending thoracic aorta imaged less easily and accurately

• misses IMH (inter mural hemorrhage) and PAU (ulcer)

Proper aortic measurement technique

Timing

• Aortic root & distal: end-diastole (AV closed, one beat before it opens)

• Aortic annulus/LVOT: mid-systole (AV open at peak systole)

Measurement conventions & orientation

• leading edge to leading edge

• made perpendicular to long axis of the aorta

• should be interpreted when indexed to an individual’s height & weight

Common locations where specific aortic measurements are obtained

• Aortic root (sinus) – largest diameter from the right coronary sinus of Valsalva to the non coronary cusp

• Sinotubular junction – measured where the curvature of the sinus transitions to the straight walls of the ascending aorta

• Mid-ascending aorta – measure at the level of the right pulmonary artery

• Distal ascending aorta – between right PA and the right innominate artery, usually found in RSB window

• Aortic arch – between the origin of the right innominate artery and the left subclavian artery

• Descending aorta – measure between the left subclavian artery and the diaphragm (proximal, mid and distal descending)

• Abdominal aorta – measure between the diaphragm and the iliac bifurcation

Definition of an aneurysm

• dilation of aorta ≥ 50% of normal diameter

• with intact vessel layers

Common locations of thoracic aneurysms

• Ascending aorta

• Descending aorta

• Aortic arch

• Thoracoabdominal

Risk factors & associated conditions (Thoracic Aortic Aneurysms)

Risk factors

• Familial/Genetic (20%)

  • Marfan Syndrome

  • Bicuspid aortic valve — related aortopathy

  • Ehlers-Danlos syndrome type IV

  • Loeys-Dietz syndrome

• Acquired

  • Hypertension

  • Family History

  • Atherosclerosis

  • Trauma

  • Tobacco use

  • Advanced age

  • Male

Types of aneurysms

True

• contain all 3 layers

• Saccular aneurysm

• Fusiform aneurysm

  • most aortic aneurysms 

False

• Pseudoaneurysm

  • rare

  • contained ruptures of the aorta

  • most of the aortic wall has been breached

  • luminal blood is held in only by a thin rim of the remaining wall or adventitia

  • result of penetrating or blunt trauma, penetrating atherosclerotic ulcers

• Dissecting aneurysms

• Sinus of valsalva

  • congenital anomaly where there is weakening of one of the sinuses resulting in dilation

  • most common is the right sinus

Role of echocardiography in evaluating aneurysms

• Identify the presence of aneurysm

• Measure max diameter of aneurysm

• Define extent of the aneurysm

• Determine involvement of the aortic valve, arch vessels

• Assess for aortic dissection

• Detect mural thrombus (difficult in TTE)

Marfan Syndrome

clinical features

• Early glaucoma

• Early cataracts

• Detached retina

• Dislocated lens

• Nearsightedness

• Spontaneous pneumothorax

• Dural ectasia (swelling of the spine)

echocardiographic features

• Proximal aorta dilation (onion-shaped)

• Sinotubular junction diameter effacement

• Pulmonary artery dilation

• Myxomatous mitral valve

• Aortic Insufficiency

• Mitral regurgitation

• Aortic dissection

• Rupture of Sinus of Valsalva aneurysm

Turner Syndrome

clinical features

• Hypertension

• Hearing loss

• Vision problems

• Kidney problems

• Autoimmune disorders (celiac disease, Hashimoto’s thyroiditis, diabetes)

• Skeletal (Scoliosis, kyphosis, brittle bones)

• Learning disabilities

• Infertility

echocardiographic features

• Associated with bicuspid aortic valve (BAV)

• Coarctation of the aorta

• Mitral valve prolapse or regurgitation

• Cardiac dextroposition

• Ventricular septal defect

• Thoracic aortic aneurysms and dissections

• Most of these patients will also demonstrate abnormal aortic arch anatomy

• Because of their stature, aorta size index must be used

Ehlers-Danlos Syndrome (vascular type)

clinical features

• Overly flexible joints

• Joint dislocations

• Early-onset arthritis

• Fragile skin may develop scarring

• Walls of blood vessels, intestines or uterus can rupture

echocardiographic features

• Aortic root dilation

• Mitral valve and aortic valve prolapse

• Aneurysm of the sinus of Valsalva

• Dilatation of the proximal innominate artery

• Membranous ventricular septal aneurysm

Loeys-Dietz Syndrome

clinical features

• Scoliosis

• Premature fusion of the skull bones

• Easily bruise

• Spontaneous pneumothorax

• Hernias

• Immune system-related problems (food allergies, asthma, eczema, inflammatory bowel disease)

echocardiographic features

• Aortic root aneurysms and dissections

  • Dissections can occur at dimensions smaller than in other inherited disorders

• Marked aorta tortuosity (winding) 

• Pulmonary artery dilation 

Bicuspid Aortic Valve (related aortopathy)

clinical and echocardiographic features

• Aortic dilation may occur in 20% to 30% of patients with BAV

• Aortic dilation typically involves the aortic root and ascending aorta

• Aneurysm may occur even in absence of significant valve dysfunction

Basic pathophysiology (Aortic Dissection)

Stanford classification (Type A vs. Type B)

Major risk factors (Aortic Dissection)

Typical clinical presentation (Aortic Dissection)

Role & limitations of echocardiography (Aortic Dissection)

Characteristics of the true & false lumen

Common complications of Aortic Dissection

General treatment differences between Type A & Type B aortic dissections

Typical location (Coarctation of the Aorta)

Common associated congenital abnormalities (Coarctation of the Aorta)

Echocardiographic findings (Coarctation of the Aorta)

Characteristic Doppler findings (Coarctation of the Aorta)

Normal anatomy & function (Pulmonary Artery)

Normal branching pattern (Pulmonary Artery)

Standard echocardiographic windows used to visualize (pulmonary artery & branch pulmonary arteries)

Normal measurement technique (Pulmonary Artery)

Pulmonary hypertension

basic echocardiographic findings & clinical significance

Pulmonary artery aneurysm

basic echocardiographic findings & clinical significance

Pulmonary artery stenosis

basic echocardiographic findings & clinical significance

Pulmonary embolism

basic echocardiographic findings & clinical significance