Cardiac allograft vasculopathy: real or a normal morphologic variant?
BACKGROUND
Naive coronary vessels may appear to have intimal thickening histologically characteristic of cardiac allograft vasculopathy (CAV). This study appraises the experimental and clinical impact of this observation.


METHODS
Tissue sections from 12 naive hearts of miniature swine, 13 native porcine hearts of recipients of heterotopic cardiac allografts, 3 native human hearts and 3 human hearts with CAV were compared with light microscopy and morphometric analysis. Results were also compared with morphometric data previously gathered from 3 grafts in a standard experimental model of CAV (rejectors) and 3 grafts harvested from swine rendered tolerant to their donor hearts (chimeras).


RESULTS
In the naive and native porcine hearts, the prevalence of CAV "mimics" was 0% to 6.94% (mean +/- SD: 1.99 +/- 1.97%) and 0% to 7.57% (2.97 +/- 2.20%), respectively (p = 0.12). The prevalence of CAV in the grafts of porcine rejectors and chimeras was 9.9% to 14.8% (12.4 +/- 2.5%) and 0.6% to 4.5% (2.6 +/- 2.0%), respectively (p < 0.05). CAV in the chimeras was similar in prevalence to that of the naive and native hearts. In native human hearts and human grafts, the prevalence was 1.86% to 2.00% (1.95 +/- 0.08%) and 9.09% to 17.50% (12.80 +/- 4.29%), respectively (p = 0.01).


CONCLUSIONS
Smooth muscle bundles inside the internal elastic laminae are similarly prevalent in human and porcine coronary vasculature. Their histologic similarity to intimal thickening of CAV could lead to an inaccurate distinction between graft tolerance and CAV in both clinical and experimental studies of heart transplantation.
Houser
Stuart
S
Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, USA. houser.stuart@mgh.harvard.edu
Muniappan
Ashok
A
Allan
James
J
Sachs
David
D
Madsen
Joren
J
D000818:Animals; D003324:Coronary Artery Disease / Q000209:etiology* / Q000473:pathology*; D003331:Coronary Vessels / Q000473:pathology*; D016027:Heart Transplantation / Q000009:adverse effects*; D006801:Humans; D013552:Swine; D013556:Swine, Miniature