Degeneration of the pulmonary autograft: an explant study.
OBJECTIVE
We sought to determine the histologic features of pulmonary autografts explanted after the Ross operation.


METHODS
Histologic sections of 30 explanted autografts and 8 normal heart valves were compared and semiquantitatively scored by a blinded cardiovascular pathologist.


RESULTS
Pulmonary autografts (n = 30) were explanted on average 6.1 +/- 0.6 years (median, 6.6 years; range, 0.1-11.7 years) after the Ross operation (n = 28) or removed at autopsy (n = 2). Twelve (43%) of the patients undergoing reoperation had no or negligible autograft insufficiency on early transthoracic echocardiography, 12 (43%) had grade 1 autograft insufficiency, and 4 (14%) had grade 1-2 autograft insufficiency. Valve regurgitation with root dilatation was the most common indication for reoperation after root replacement (n = 26 [93%]) and regurgitation after subcoronary implanted autografts (n = 2 [7%]). Microscopy of the autograft explants revealed normal laminar architecture and cellularity. Wall specimens were characterized by reduced and fragmented elastin and increased collagen levels (fibrosis). Medial elastin changes were associated with the presence of hypertrophic smooth muscle cells. Fibrosis was most severe in the adventitia. Intimal thickening was a common finding. Valve explants showed significant thickening caused by fibrocellular tissue on the ventricular surface and marked thickening of the free margin. An autopsy explant with normal function before death showed similar features.


CONCLUSIONS
Pulmonary autograft explants showed severe aneurysmal degeneration of the wall, which was characterized by intimal thickening, medial elastin fragmentation, and adventitial fibrosis. Valve leaflets were thickened. The presence of these features in a nonfailing explant suggests these changes represent a common mode of remodeling.
Schoof
Paul H
PH
Department of Cardiothoracic Surgery, University Medical Center Leiden, Leiden, The Netherlands. P.H.Schoof@lumc.nl
Takkenberg
Johanna J M
JJ
van Suylen
Robert-Jan
RJ
Zondervan
Pieter E
PE
Hazekamp
Mark G
MG
Dion
Robert A E
RA
Bogers
Ad J J C
AJ
D000293:Adolescent; D000328:Adult; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D011183:Postoperative Complications / Q000601:surgery*; D011664:Pulmonary Valve / Q000473:pathology* / Q000637:transplantation*