Commissural dehiscence and pannus formation of porcine heart valve bioprostheses

A 10-year comparison of explanted Hancock-II and Carpentier–Edwards supraannular bioprostheses

BACKGROUND

Bioprosthetic heart valves are more frequently being used in valve replacement procedures today. Although second-generation bioprosthetic valves have improved functionality over their first-generation counterparts, they still often fail due to primary tissue degeneration.

METHODS

This study examines two second-generation porcine valves after surgical explantation, the Hancock-II (HAN; Medtronic Heart Valve Division, Irvine, CA, USA) and the Carpentier-Edwards supraannular (CE-SAV; Baxter Healthcare Corporation, now Edwards LifeSciences, Irvine, CA, USA), with special attention to morphological/histological changes and reasons for valve failure. A total of 98 HAN and 65 CE-SAV valves were explanted and seen over a 10-year period.

RESULTS

CE-SAV valves had a longer average implant duration than HAN valves (13.9+/-3.9 years vs. 10.0+/-5.1 years). Compared with HAN valves, CE-SAV valves also had a higher incidence of stent deformation (41.5% vs. 14.3%), calcification (75.4% vs. 54.1%), and pannus (100% vs. 91.8%).

CONCLUSIONS

The greater degenerative changes seen with CE-SAV valves over HAN valves may be due to the longer implant duration of CE-SAV valves in this series. To our knowledge, the present study is the first direct morphological comparison of these two valve models.

Commissural dehiscence: A rare and peculiar cause of porcine valve structural deterioration

OBJECTIVE

Calcification is the main cause of structural valve deterioration; however, other causes of failure have been identified, and among them, dehiscence of a commissure from the stent has been reported in several models of porcine valves. The aim of this study was to analyze the rate and mode of occurrence of this complication in first- and second-generation porcine bioprosthetic explants.

METHODS

Among 586 porcine xenografts explanted and analyzed at the Institute of Pathological Anatomy of the University of Padua, 17 (2.9%) have been replaced for incompetence because of commissural dehiscence. All these explants were in the mitral position, with the exception of a Carpentier-Edwards supra-annular aortic valve prosthesis.

RESULTS

Dehiscence was observed in 9 (1.9%) of 455 Hancock standard explants, in 1 (3.2%) of 31 Hancock II, in 3 (8.6%, 2 standard and 1 supra-annular) of 35 Carpentier-Edwards, in 1 (2.4%) of 42 Bioimplants, and in 3 (50%) of 6 Xenotech after a mean time function of 157 +/- 50, 156, 96 +/- 29, 143, and 130 +/- 8 months, respectively. Dehiscence was the sole cause of incompetence in 6 cases. An impending commissural dehiscence caused by blood creeping was observed in one case. This might be an explanation for the dehiscence other than excessive trimming of the aortic wall.

CONCLUSIONS

Commissural dehiscence is an uncommon and peculiar mode of failure of porcine valves implanted in the mitral position and was observed earlier and more frequently with Carpentier-Edwards porcine explants (P < .05). We speculate that pericardial strip protection of the suture between the Dacron fabric and porcine aortic wall, as used in the Biocor porcine valve, might prevent this complication.