Distensible behavior of pulmonary artery

¹ Cardiovascular Research Laboratory, College of Medical Evangelists, Los Angeles County General Hospital, Los Angeles, California

Pressure-volume determinations were made in a reproducible proximal segment of the pulmonary arterial system of swine using a known reciprocating volume at physiologic rates of cycling. The distensible response of vessels separated from normal supporting structures depended on extraneous mechanical influences. Antecedent freezing decreased distensibility and altered the pattern of response. At low inputs fresh specimens in continuity with supporting structures displayed pressure-volume curves of increased distensibility with increasing volume. At high inputs the curves were of sigmoid shape with a lower region of increased instantaneous distensibility and a higher region of decreased instantaneous distensibility. The findings differ from distensibility studies of large arteries by other methods.