Traumatic leaflet injury during the use of percutaneous valves: a comparative study of balloon- and self-expandable valved stents

No comparison of balloon- or self-expandable valved stents (VSs) regarding tissue injury (if any) has been reported yet. The objective was to evaluate the occurrence and compare the severity of traumatic injury to leaflets from balloon- or self-expandable VSs. Twelve homemade VSs were used for this experiment. These three-leaflet bovine pericardial bioprostheses had either a stainless steel (Group A) or a nitinol stent (Group B). After a 30-min period of compression (external diameter of VS reduced to 7 mm), the prostheses were deployed by balloon inflation (Group A) or by unsheathing (Group B). After H&E staining, pericardial leaflets were subsequently analyzed qualitatively and quantitatively for microscopic lesions. Non-crimped pericardial leaflets were used as a control group (Group C). All deployed VSs had microscopic lesions evocating traumatic injury to pericardial leaflets. Transverse fractures and longitudinal cleavages were the two main lesions encountered. Transverse fractures (no. per field) were significantly more frequent in the VS in comparison with the control group: 5 (range: 0-13), 4 (range: 0-9) and 0 (range: 0-1) in Groups A, B and C, respectively (P < 0.001). Cleavages (no. per field) were also more frequent with balloon-expandable VSs compared with self-expandable VSs [3 (range: 0-7) vs 1(range: 0-8); P = 0.03]. Traumatic injury to the pericardial leaflets does occur during crimping and deployment of balloon- or self-expandable VSs. Injury may be more severe with the balloon-expandable VSs. The impact of such an injury on prosthesis durability requires a further investigation.