Is cutting stress responsible for the limited durability of heart valve bioprostheses?

Páez, J. M. García; Martín, A. Carrera San; Sestafé, José Vicente García; Millán, Isabel; Jorge, Eduardo; Candela, Ignacio; Castillo‐Olivares, J. L.

doi:10.1016/s0022-5223(19)35503-5

Cited by 34 publications

(16 citation statements)

References 3 publications

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“…The suture provokes a significant loss of resistance to rupture ( p < 0.01; Table I). This outcome has also been well documented in calf pericardium 23, 24. Neither the type of suture material nor the angle of suture placement with respect to the longitudinal axis, the site at which the stress is applied, influence the outcome.…”

Section: Discussionmentioning

confidence: 54%

Mechanical behavior of chemically treated ostrich pericardium subjected to uniaxial tensile testing: influence of the suture

Páez

Carrera

Herrero

et al. 2002

J. Biomed. Mater. Res.

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The mechanical behavior of sutured ostrich pericardium was studied by uniaxial tensile testing. One hundred forty-four tissue specimens were assessed: 96 sutured samples (48 in which a centrally located suture was placed at an angle of 90 degrees with respect to the longitudinal axis, whereas in the remaining 48, a centrally located suture was placed at a 45 degrees angle to the longitudinal axis, in sets of 12 samples each, sewn with sutures made of Gore-Tex, nylon, Prolene, or silk), and 48 unsutured controls. Each group of 24 samples sewn at one angle or the other with the different suture materials was assayed together with a corresponding control group of 12 unsutured samples. The mean tensile strengths in the unsutured controls ranged between 30.16 MPa and 43.42 MPa, whereas those of the sutured sets ranged from 14.68 MPa to 21.91 MPa. The latter presented a statistically significant loss of resistance (p < 0.01) when compared with the unsutured tissue samples. The angle of the suture with respect to the longitudinal axis influenced the degree of shear stress produced by the suture, as well as the behavior of the different suture materials used. The set of samples sewn with Prolene appeared to be that most sensitive to changes in the angle of the suture, whereas tissue sewn at a 45 degrees angle with Gore-Tex presented lower shear stress values in comparison with samples in which the other three materials were used. A method of tissue selection based on morphological and mechanical criteria was used to ensure the homogeneity of the results in such a way that the coefficients of determination (R2) for the stress/strain curve fitting equation ranged between 0.888 and 0.995. This excellent fit made it possible, applying regression analysis, to predict the mechanical behavior of a specimen by determining that of a contiguous tissue sample. Thus, it should be possible, at least theoretically, to characterize the behavior of a specific region or zone of the biomaterial. In conclusion, ostrich pericardium exhibits strong resistance to rupture, even when sutured. The selection method used ensures the homogeneity of the samples and, thus, of the results. The angle of the suture with respect to the longitudinal axis, where the load is centered, determines the shear stress produced by the suture and the mechanical behavior of each suture material.

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Section: Discussionmentioning

confidence: 54%

Mechanical behavior of chemically treated ostrich pericardium subjected to uniaxial tensile testing: influence of the suture

Páez

Carrera

Herrero

et al. 2002

J. Biomed. Mater. Res.

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“…Although the number of cycles was low in this study, the application of long‐term fatigue testing to a biomaterial like calf pericardium is known to produce changes in its structural composition (11). The resistance to tearing, indicated by the force required to produce it, guarantees the safety of a biomaterial, which is subjected to shearing force when employed in a cardiac valve leaflet (15,18).…”

Section: Discussionmentioning

confidence: 99%

Changes in the Mechanical Properties of Chemically Treated Bovine Pericardium After a Short Uniaxial Cyclic Test

Claramunt¹,

Álvarez-Ayuso²,

García-Páez³

et al. 2012

Artificial Organs

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The mechanical behavior of calf pericardium, a biomaterial utilized in the manufacture of cardiac bioprostheses, in response to a short tensile cyclic test has been evaluated. The trial involved 120 samples cut longitudinally or transversely, subjected to 10 cycles until a stress of between 1 and 3 MPa was reached. Tests of hardness and tear propagation were performed, and the results were compared with a control series. The energy loss was also computed, and it was approximately 10-fold greater in the first cycle than the loss in the subsequent nine cycles. Despite this singularity, they correlated very precisely. The effect of the direction in which the tissue is cut on energy loss was not significant nor the difference between hardness prior to and after testing. The results of the tear propagation tests gave no statistical differences prior to and after testing. From the obtained results, it seems that the test carried out does not affect significantly the mechanical properties of calf pericardium.

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“…Suture materials present a high resistance to strain and rupture [21], but produce a marked interaction or internal shear stress when used to shape a bioprosthetic cardiac valve leaflet made of calf pericardium since the pericardium is much less resistant and more elastic [13,15,16]. This interaction can be considered one of the causes of valve failure, sometimes occurring early in time [14,18,22].…”

Section: Discussionmentioning

confidence: 99%

“…If, as it appears, sutures play a negative role in the resistance of bioprostheses made of calf pericardium [18], it would be beneficial to replace them with other means of tissue bonding. The use of biological glues or adhesives would be ideal if they guaranteed a good mechanical resistance over time and a good elastic behaviour that would reduce the internal stresses in the valve structure.…”

Section: Introductionmentioning

confidence: 99%

Resistance to Tensile Stress of a Bioadhesive Utilized for Medical Purposes: Loctite 4011

Páez

Herrero²,

Millán

et al. 2004

J Biomater Appl

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Sutures are the materials presently employed to secure and give shape to the valve leaflets of cardiac bioprostheses. Their high resistance and low degree of elasticity in comparison with the calf pericardium of which the leaflets are made generates internal stresses that contribute to the failure of the bioprostheses. Biological adhesives are bonding materials that have begun to be utilized in surgery, although there is a lack of experience in their use with inert tissues or bioprostheses. We report our study of Loctite 4011, a biological glue composed of a cyanoacrylate that has been employed for medical purposes, in which samples of pericardium bonded with this adhesive were subjected to uniaxial tensile stress. The samples were glued in such a way as to leave an overlap of 1 cm2 between the surfaces of the tissue. The series included 83 samples: 12 tested 24 h after bonding, 17 after 45 days, 17 after 90 days, 19 after 106 days and 18 after 152 days. The samples subjected to deferred trials were preserved using three types of chemical substances: glutaraldehyde, glycerol or saline plus antibiotics. The mean resistance to rupture of the series tested 24 h after gluing was 0.15 MPa (1.47 machine kg). This resistance remained nearly unchanged, regardless of the preservation solution employed, for at least 152 days, the time at which the study ended. The stress-strain curves demonstrated a high degree of elasticity throughout the 152 days, a finding that was not influenced by the preservation solution. This adhesive showed a considerable resistance to tensile stress, although probably insufficient to replace sutures. However, it maintained a surprisingly high degree of elasticity in the samples. Perhaps the time has come to combine these two elements, sutures and adhesives, to improve the elasticity of the structure without a loss of resistance, and increase the durability of bioprostheses.

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Is cutting stress responsible for the limited durability of heart valve bioprostheses?

Cited by 34 publications

References 3 publications

Mechanical behavior of chemically treated ostrich pericardium subjected to uniaxial tensile testing: influence of the suture

Mechanical behavior of chemically treated ostrich pericardium subjected to uniaxial tensile testing: influence of the suture

Changes in the Mechanical Properties of Chemically Treated Bovine Pericardium After a Short Uniaxial Cyclic Test

Resistance to Tensile Stress of a Bioadhesive Utilized for Medical Purposes: Loctite 4011

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