Collateral Flow in Pulmonary Hypertension


Figure 1. Normal Bronchial Artery

Bronchial arteries supply the airways and provide collateral blood flow to pulmonary arteries that become obstructed. Bronchial arteries have a single internal elastic lamina. Here, the central bronchial artery has eccentric intimal thickening. Multiple small branches surround this artery. Elastic van Gieson stain

Find the central bronchial artery.


Figure 2. Bronchus with Expanded Bronchial Arteries

This bronchus from the 52-year-old man shows an increased number of dilated bronchial vessels, representing an expanded collateral circulation. A bronchial sero-mucous gland is present. The luminal epithelium, which should be at the top is absent--a postmortem change. A segment of bronchial cartilage is present at the lower right.


Figure 3. Pleural "Spider"

Increased perfusion of pleural bronchial arteries may produce "spider-like" vessels radiating from a central focus, similar to those seen in hepatopulmonary syndrome.

This pleural "spider" is from another patient with PAH.

Figure 4. Pleural Bronchial Vessels

Here, a collection of dilated bronchial vessels in the pleura corresponds to the "spider" shown above.

Comment: Dogs developed severe pulmonary hypertension with plexiform and dilation lesions after anastomosis of the aorta to a single segmental artery to the lower lobe. The dilation lesions related to plexiform lesions were filled with gelatin injected via the aorta into the bronchial arteries. The gelatin also appeared in the pulmonary artery [1]. This expansion of collaterals between bronchial and pulmonary arteries bypasses the obstructed pulmonary vessels. During life, some pulmonary artery to bronchial artery flow may bypass the capillary bed to return to the left heart via the pulmonary veins. Such bypassing of capillaries could account for the intrapulmonary shunt that has been demonstrated following vasodilator therapy in some patients with PAH [2], including the 52-year-old man in the case discussion.

References: To return to reference section after viewing abstract, click here before clicking on "abstract".

1. Saldana M, Harley R, Liebow A, Carrington C. Experimental extreme pulmonary hypertension and vascular disease in relation to polycythemia. Am J Pathol 1968; 52:935-981.

2. Castro P, Bourge R, McGiffin D, Benza R, Fan P, Pinkard N, McGoon M. Intrapulmonary shunting in primary pulmonary hypertension. An observation in two patients treated with epoprostenol sodium. Chest 1998; 114:334-336. Abstract

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