Traumatic leaflet injury: comparison of porcine leaflet self-expandable and bovine leaflet balloon-expandable prostheses.

OBJECTIVES: The main goal of this study was to compare the occurrence of post-deployment leaflet injury between prostheses made of porcine and bovine pericardium. METHODS: Two types of prostheses, self-expandable prostheses with porcine pericardial leaflet on one side and balloon-expandable prostheses with bovine pericardial leaflet on the other side, were used. In each group, crimped prostheses were compared with control non-crimped prostheses. Following a 15-min period of crimping, prostheses were deployed, and their leaflets were removed and subjected to analyses. The analyses included determination of global and local hydraulic conductance of the leaflets, leaflet plasma insudation and microscopic analysis. The results were expressed as percentage (standard error of the mean) or median (interquartile range). RESULTS: A significant increase in the global hydraulic conductance was only observed in the crimped balloon-expandable prostheses: 20.1 (15.5-41.2) ml/h/m2/mmHg vs 12.3 (9.0-15.6) ml/h/m2/mmHg (P = 0.021). Similarly, areas of marked staining (a marker of local hydraulic conductance) were only seen in the bovine pericardium balloon-expandable prostheses. The incidence of leaflet plasmatic insudation was increased in the crimped prostheses compared with the control prostheses. The microscopic study revealed a higher occurrence of traumatic lesions in the crimped prostheses in comparison with the control prostheses: 33.3 ± 21.1% vs 5.5 ± 5.5% (P = 0.039) and 44.4 ± 20.5% vs 5.5 ± 5.5% (P = 0.017) in the bovine and the porcine leaflets, respectively. CONCLUSIONS: Post-deployment leaflet injury occurred in both types of prostheses. However, alteration of the global and local hydraulic conductance was important in the bovine pericardium balloon-expandable prostheses.

Crimping and deployment of balloon-expandable valved stents are responsible for the increase in the hydraulic conductance of leaflets.

OBJECTIVES: Leaflet injury has been documented to occur during the deployment of valved stents (VSs). The pathological aspects, however, of this injury are difficult to quantify. Conversely, the hydraulic conductance of a (pericardial) membrane may be easily determined. The impact of crimping and deployment of VS on this parameter was therefore investigated. METHODS: Bovine pericardial square (25 × 25 mm) patches were placed within a pressure chamber and their hydraulic conductance was determined. The influence of the pressure gradient and tissue thickness on this parameter was analysed. Six balloon-expandable VS were constructed. The hydraulic conductance of their bovine pericardial leaflets was determined before and after VS crimping and deployment in four of them. Pericardial leaflets of non-crimped VS were used as controls. RESULTS: Hydraulic conductance increased insignificantly with the pressure level within the chamber: from 128 ± 26.9 ml/h/m(2)/mmHg at a pressure of 50 mmHg to 232.3 ± 51.9 ml/h/m(2)/mmHg at a pressure of 250 mmHg (P = 0.117). Hydraulic conductance was not correlated to pericardial thickness, for thickness measurements ranging from 0.34 to 0.76 mm. The hydraulic conductance of VS leaflets significantly increased immediately after crimping from 45.2 ± 7.6 to 667.9.0 ± 527.2 ml/h/m(2)/mmHg (P < 0.001). This increase was still observed 24 h after VS deployment. No change in hydraulic conductance occurred in the control group. CONCLUSIONS: The determination of the hydraulic conductance of pericardial patches was easy to perform, reproducible and not influenced by tissue thickness. The hydraulic conductance of pericardial leaflets dramatically increased after VS crimping and deployment. This parameter might be, in the future, a useful noninvasive tool in studying leaflet trauma.