C. Stefanadis et al., EFFECT OF VASA VASORUM FLOW ON STRUCTURE AND FUNCTION OF THE AORTA INEXPERIMENTAL-ANIMALS, Circulation, 91(10), 1995, pp. 2669-2678
Background It is known that vasa vasorum flow contributes substantiall
y to the nutrition of the outer layers of the thoracic aorta. This inv
estigation was undertaken to test the hypothesis that impairment of va
sa vasorum flow would alter the structure of the aortic wall and chang
e the elastic properties of the aorta. Methods and Results The periaor
tic fat that contains the vasa vasorum for the ascending aorta was rem
oved in seven anesthetized dogs, and the results were compared with th
ose obtained from six weight-matched sham-operated control dogs. Aorti
c pressures, aortic diameters, and aortic distensibility were obtained
before and 30 minutes and 15 days after removal of the periaortic vas
a vasorum network. Aortic pressures were measured directly with a flui
d-filled catheter. Aortic diameters were measured simultaneously with
aortic pressures with an elastic, air-filled ring connected to a trans
ducer. Aortic distensibility was calculated by the formula 2Xpulsatile
change in aortic diameter/(diastolic aortic diameterXpulse pressure).
Histology was performed in transverse blocks of aortic wall at the en
d of the experiment in both groups. The efficacy of the technique for
the interruption of vasa vasorum blood supply to the aortic wall was d
emonstrated by histology in four additional animals that were killed w
ithout removal of vasa vasorum (two animals) and immediately after vas
a vasorum removal (two animals). At baseline, heart rate, aortic press
ures, aortic diameters, and aortic distensibility were similar in the
two groups. A significant decrease in aortic distensibility was observ
ed 30 minutes and 15 days after removal of the vasa vasorum in the exp
erimental group (baseline, 3.453+/-1.023; 30 minutes, 2.521+/-0.760; 1
5 days, 1.586+/-0.488 10(-6) . cm(2) . dyn(-1); F=9.532, P<.001). No c
hanges were observed in aortic distensibility in the control group dur
ing the experiment. Histology of the aorta revealed medial necrosis, a
lterations of the elastin fibers, and a trend (P=.055) for altered col
lagen-to-elastin ratio in a region occupying more than the one (outer)
half of the media of the experimental group animals. No changes were
observed in the control group. Conclusions The findings of the present
study demonstrated that interruption of vasa vasorum flow led to an a
cute decrease in the distensibility of the ascending aorta. Moreover,
structural changes of the aortic wall and further deterioration of the
elastic properties of the aorta occurred 15 days after vasa vasorum r
emoval.