Am. J. Respir. Crit. Care Med.,
Volume 158, Number 4, October 1998, 1245-1252
Airway Structure and Function in
Eisenmenger's Syndrome
KAREN O.
MCKAY,
PETER R. A.
JOHNSON,
JUDITH L.
BLACK,
ALLAN R.
GLANVILLE,
and
CAROL L.
ARMOUR
Departments of Pharmacology and Pharmacy, University of Sydney; and the Cardiopulmonary Transplant Unit,
St. Vincent's Hospital, Darlinghurst, New South Wales, Australia
The responsiveness of airways from patients with Eisenmenger's syndrome (n = 5) was compared
with that in airways from organ donors (n = 10). Enhanced contractile responses to cholinergic stimulation were found in airways from patients with Eisenmenger's syndrome. The maximal responses
to acetylcholine, carbachol, and parasympathetic nerve stimulation in airway tissue from these patients were 221%, 139%, and 152%, respectively, of the maximal responses obtained in donor tissue.
Further, relaxation responses to isoproterenol and levocromakalim were absent (n = 2) or markedly impaired (n = 3) in airways from patients with Eisenmenger's syndrome. This attenuated relaxation
response was nonspecific in that it was also absent after vasoactive intestinal peptide, sodium nitroprusside, papaverine, and electrical field application. These observations can most likely be explained
by a decrease in intrinsic smooth muscle tone, as precontraction of airways revealed relaxation responses that were equivalent to those obtained in donor tissues. Morphometric analysis of tissues
used for the functional studies revealed no differences in the airway dimensions (internal perimeter) or airway wall components (e.g., smooth muscle, cartilage) or total area to explain these observations. Although the mechanism for this observed decrease in intrinsic airway smooth muscle tone is
not certain, it may be due to alteration in the substructure of the airway wall or, alternatively, may result from the continued release of depressant factors in the vicinity of the smooth muscle which permanently alters smooth muscle responsiveness.
