Pulmonary Vessels

*It is not possible to measure the diameter of the MPA from the plain film (usually subjective); but if there are variable

degrees of bulging, means enlarged MPA.

*Assessment of the hilar pulmonary arteries is more objective & the diameter of the Rt. lower lobe artery at its

mid-point (normally 9 – 16 mm).

*The size of pulmonary vessels with the lung reflects the pulmonary blood flow.

*Increase pulmonary blood flow is seen in ASD, VSD& , PDA, & all of these will lead to Systemic to Pulmonary (Lt.

to Rt. shunt) & these will to increase pulmonary blood flow.

Pulmonary Vessels

*Hemodynamically significant Lt. to Rt. shunt is (2/1 ratio or more) & this will produce CXR findings; if less ratio

there will be no CXR findings & all the pulmonary vessels will (from the MPA to the periphery of the lung) will be

enlarged, & this is called "Pulmonary Plethora."

*There is good correlation between the size of the vessel on CXR & degree of the shunt.

*Decrease pulmonary blood flow, all the vessels are small

" Pulmonary Oligemia."

*The commonest cause of decrease pulmonary blood flow is TOF & pulmonary stenosis.

*Obstruction of the Rt. ventricle outflow + VSD will lead to Rt. to Lt. shunt.

*Pulmonary stenosis will cause oligemia only is severe cases & babies or very young children.

Pulmonary Vessels

Pulmonary Arterial Hypertension

*The pressure in the pulmonary artery depends on:

1 -Cardiac output.

2 -Pulmonary vascular resistance.

Pulmonary Arterial Hypertension

*Conditions that cause significant pulmonary arterial hypertension all increase the resistance of blood flow

through the lungs, examples:

1 -Various lung diseases (cor pulmonale). 2 -Pulmonary embolism.

3 -Pulmonary arterial narrowing in response to mitral valve diseases or Lt. to Rt. shunt.

4 -Idiopathic pulmonary hypertension.

Pulmonary Arterial Hypertension

*By CXR: There will be enlargement of the mean pulmonary artery + the hilar pulmonary artery, vessels within the lung tissue are normal or small.

*Eisenmenger's syndrome:

Greatly raised pulmonary artery resistance in associationwith ASD, VSD, & PDA leading to reverse shunt (i.e. : Rt. to Lt. shunt).

Pulmonary Arterial Hypertension

*The cause of pulmonary arterial hypertension may be visible on the CXR as cor pulmonale & mitral valve

diseases.

Pulmonary Arterial Hypertension due to ASD & Eisenmenger's

syndrome

Pulmonary Venous Hypertension

*The commonest causes of pulmonary venous hypertension are:

1 -Mitral valve diseases. 2 -Lt. ventricular failure.

*In normal upright person (by CXR) the lower zone vessels

are larger than the upper zone.

*In pulmonary venous hypertension the upper zone vessels are enlarged.

*In severe cases, the upper zone vessels become larger

than that of the lower zone, & eventually Pulmonary Edema will supervene & may obscure the blood vessels.

Pulmonary Venous Hypertension

Pulmonary Venous Hypertension in a patient with Mitral Valve

Disease

Aorta *With aging the aorta becomes elongated, elongation

necessarily involve unfolding, where the ascending aorta will deviate to the Rt. & the descending aorta to the Lt.,

because the aorta is fixed at the aortic valve & the diaphragm.

*Unfolding aorta is easily confused with aortic dilatation. *Aortic dilatation of the ascending aorta is due to:

1 -Aneurysm. 2 -Aortic regurgitation or aortic stenosis.

3 -Systemic hypertension. *The two common causes of descending aortic aneurysm

are: 1 -Atheroma.

2 -Aortic dissection. (Also, there is a rare cause as previous trauma following decelerating injury.)

Aorta *By CXR:

1 -The diagnosis of aortic aneurysm may be obvious, but substantial dilatation may be needed before the bulge of

Rt. mediastinal border can be recognized.

2 -Atheromatous aneurysm invariably shows calcification of their walls.

*CT scan with IVCM or CT angiography or MRA are very useful to assess the aneurysm.

Note:

IVCM = I.V. Contrast Media.MRA = Magnatic Resonance Angiography.

Dissecting Aortic Aneurysm

It is important to know the extent of the dissecting aneurysm as those involving the ascending aorta are treated surgically & those confined to the descending aorta are treated with hypotensive drugs.

*By CXR: Two congenital aortic anomalies can be seen, & they are:

1 -Coarctation of Aorta. 2 -Rt. sided aortic arch, in association with TOF,

Pulmonary Atresia, & Truncus Arteriosus, or it also can be isolated with no clinical significance.

Dissecting Aortic Aneurysm

Trans-Esophageal Echocardiogram showing the True (T) & False (F)

lumina in the descending aorta

Dissecting Aortic Aneurysm

CT-scan showing the displaced intima (arrows) separating the

true & false luminae in the ascending & descending aorta