DYNAMICS OF PULMONARY CIRCULATION 1 679 



NORMAL 



NUTRIENT 



© 



BRONCHIECTASIS 



PA 



C2) 



HEMODYNAMIC? 



TETRAD 



©PA 



COi 



RESPIRATORY ? 



® 



PROXIMAL 

 BV 



mm Hg 5 mm Hg 



NORMAL 



10 mm Hg 5 mmHg 



RIGHT HEART FAILURE 



fig. 1 1 . Pulmonary collateral circula- 

 tion. Upper half: The arterial portion. A: 

 usual nutrient function; B: expansion to 

 constitute a hemodynamic burden, as in 

 diffuse suppurative disease; C: participa- 

 tion in external respiration when systemic 

 arterial hypoxemia coexists with inade- 

 quate pulmonary arterial blood flow. 

 Lower half: The venous portion. D: usual 

 emptying of proximal bronchial veins; E: 

 alternate emptying of proximal bronchial 

 veins when right atrial pressures exceed 

 left atrial pressures. [After Fishman (133).] 



pulmonary and systemic circulations are grossly 

 visible (264). 



The proliferation generally does not affect the 

 entire collateral circulation in a uniform manner 

 (fig. 11). Thus, in the portion of the lung which lies 

 adjacent to an area of pulmonary inflammation, as 

 well as in the lung with a severely compromised 

 pulmonary arterial blood supply, it is the arterial 

 portion of the collateral circulation which expands; 

 on the other hand, the venous portion of the collateral 

 circulation undergoes the more striking expansion in 

 certain types of pulmonary emphysema and in mitral 

 stenosis (263). If the expanded collateral circulation 

 becomes sufficiently large — as in diffuse suppurative 



disease of the lung (263) — it may carry large volumes 

 of blood, and transmit systemic blood pressures, to 

 the point of constituting a hemodynamic burden on 

 the pulmonary circulation. 



It should be noted that as the collateral circulation 

 proliferates, the difficulties in measuring the rate of 

 collateral blood flow also grow. Particularly trouble- 

 some, from the technical point of view, are the 

 multiple origins of the collateral arterial branches on 

 the one hand and the alternate venous outlets on the 

 other (fig. 1 1). Indeed, on account of this anatomical 

 arrangement, it is difficult to measure volumetrically 

 the total collateral blood flow even in the open-chest 

 dog in which the heart and thoracic vessels are 



