Geometrical and Stress Analysis of Factors Associated With Stent Fracture After Melody Percutaneous Pulmonary Valve Implantation

Q: What is the clinical evidence from this study?

Study design: Cohort. Population: Pulmonary artery conduit dysfunction treated with percutaneous pulmonary valve implantation (PPVI) (n=42). Intervention: 3D stent circularity preservation (change in radial asymmetry during recoil) and compressive stresses during balloon deflation. Primary outcome: Melody stent fracture within 1 year after percutaneous pulmonary valve implantation (OR 0.98, 95% CI 0.96-0.99, p=0.006).

Q: What does this research mean for the field?

Preserved stent circularity and lower compressive stresses after balloon deflation are independently associated with a reduced risk of Melody stent fracture after percutaneous pulmonary valve implantation. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.NEUTRAL.

Daria Cosentino; Michael A. Quail; Giancarlo Pennati; Claudio Capelli; Philipp Bonhoeffer; Vanessa Díaz‐Zuccarini; Andrew M. Taylor; Silvia Schievano

doi:10.1161/circinterventions.113.000631

August 1, 2014Circulation Cardiovascular InterventionsOpen Access

Geometrical and Stress Analysis of Factors Associated With Stent Fracture After Melody Percutaneous Pulmonary Valve Implantation

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Key result

Preserved stent circularity after balloon deflation is linked to ~2% lower Melody fracture risk.

OR 0.98
95% CI 0.96-0.99
P=0.006
n=42

Why the study?

Do 3D geometric variations and mechanical stresses during balloon deflation and the cardiac cycle predict stent fracture within 1 year in patients undergoing Melody percutaneous pulmonary valve implantation?

Key Points

To identify geometric and biomechanical stress factors associated with Melody stent fracture using patient-specific three-dimensional reconstructions and computer simulations.
Reconstructed in situ 3D stent geometries from biplane fluoroscopy images in 42 patients after balloon inflation, systole, and diastole to measure 21 geometric parameters across struts, cells, and sections.
Developed patient-specific finite element computer simulations to replicate stent deformation history and evaluate maximum and minimum principal stresses during balloon deflation and the cardiac cycle.
Evaluated associations with stent fracture using univariate and multivariable logistic regression analyses combining geometric and stress variables.
Univariate analysis identified decreased stent circularity after balloon deflation (OR 0.98; 95% CI, 0.96-0.99; P=0.006) and large compressive stresses during deflation (OR 0.98; 95% CI, 0.96-0.997; P=0.03) as significant risk factors for fracture.
In multivariable logistic regression, post-deflation section deformation and compressive stress were independently associated with fracture risk.
The final statistical model correctly classified fracture status in 93% of patients, with a sensitivity of 0.90 (95% CI, 0.55-0.98) and a specificity of 0.94 (95% CI, 0.79-0.99).

Study Design

Type

Cohort (n=42)

Multicenter

No

Structured PICO

Do 3D geometric variations and mechanical stresses during balloon deflation and the cardiac cycle predict stent fracture within 1 year in patients undergoing Melody percutaneous pulmonary valve implantation?

P

Population

42 patients (age range 7-71 years, 35.7% female) undergoing percutaneous pulmonary valve implantation with the Melody device at a single center in the United Kingdom, followed for 1 year.

E

Exposure

3D in situ stent geometric reconstruction from procedural biplane fluoroscopy images and patient-specific finite element (FE) stress analysis (evaluating 21 geometric parameters and 8 stress parameters during balloon deflation/recoil and cardiac cycle)

O

Outcome

Melody stent fracture within the first year after successful PPVI, detected and assessed using routine follow-up chest x-ray images at 1, 6, and 12 monthssafety

Main Result

Odds Ratio: 0.98 (95% CI 0.96–0.99)

p-value: p=0.006

3D fluoroscopic reconstruction and finite element stress analysis immediately after Melody valve deployment can accurately identify patients at high risk for subsequent stent fracture based on stent circularity loss and compressive recoil stress, potentially enabling tailored follow-up.

Limitations

Follow-up data at 1 year relied on chest radiographs without dynamic fluoroscopy, potentially underestimating stent fractures.
Finite element analysis did not include residual stresses from asymmetrical manual crimping or multiple post-PPVI balloon inflations.
Inability to distinguish the effects of implantation site/tissue environment from percutaneous delivery technique on stent recoil.
Small cohort size (n=42) with potential for model overfitting, requiring prospective validation.
3D reconstruction and parameter measurement require specialized technical image processing not widely available in clinical settings.
Did not differentiate between clinically significant (major) and minor stent fractures.
Follow-up at 1 year used chest radiographs without dynamic fluoroscopy, which may underestimate the number of stent fractures
Finite element analysis did not account for residual stresses from asymmetrical manual crimping or multiple post-PPVI balloon inflations
Cannot distinguish the effects of implantation site/surrounding tissue environment from percutaneous delivery technique on stent recoil
Small sample size with risk of overfitting, requiring prospective validation
3D reconstruction process requires specialized technical image processing unavailable in many clinical environments
Analysis did not differentiate between major (hemodynamically significant) and minor stent fractures

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Implication

May inform deployment technique to reduce fracture risk; leaves open prospective validation in Melody PPVI.

Abstract

BACKGROUND: Patients treated with the Melody device (Medtronic) for percutaneous pulmonary valve implantation experience stent fractures in ≈25% of the cases. The aim of this study is to identify the risk factors associated with fracture using 3-dimensional (3D) analyses. METHODS AND RESULTS: In situ 3D shape of the Melody stent was reconstructed from 42 patients using procedural biplane fluoroscopy images, after balloon inflation, at systole and diastole. Four geometric parameters at systole and their variation during balloon deflation and cardiac cycles were measured to describe the 3D strut, cell, section, and stent configuration. Furthermore, patient-specific computer simulations were set up to replicate the history of stent deformations for each patient. Maximum and minimum principal stresses resulting from these analyses were monitored during balloon deflation and cardiac cycle. Univariate logistic regression analyses of 21 geometric parameters and of 4 stress parameters respectively, identified the decreased stent circularity after balloon deflation (odds ratio 0.98; 95% confidence interval, 0.96-0.99; P=0.006) and large compressive stresses during balloon deflation (odds ratio, 0.98; 0.96-0.997; P=0.03), as associated with the risk of fracture. In a multivariable logistic regression model, the 2 covariates identified on univariate analysis (1 geometric and 1 stress) were found to be independently associated with the risk of fracture. The resultant statistical model correctly identified fracture/no fracture in 93% of patients. CONCLUSIONS: Changes in stent section shape after balloon deflation are important variables influencing fracture. This methodology could help design tailored follow-up for patients after percutaneous pulmonary valve implantation.

Discussion

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Cite This Study

Cosentino et al. (2014) conducted a cohort in Pulmonary artery conduit dysfunction treated with percutaneous pulmonary valve implantation (PPVI) (n=42). 3D stent circularity preservation (change in radial asymmetry during recoil) and compressive stresses during balloon deflation was evaluated on Melody stent fracture within 1 year after percutaneous pulmonary valve implantation (OR 0.98, 95% CI 0.96-0.99, p=0.006). Preserved stent circularity after balloon deflation (OR 0.98, 95% CI 0.96-0.99, P=0.006) and lower compressive stresses (OR 0.98, P=0.03) were associated with reduced Melody stent fracture risk.

synapsesocial.com/papers/6a8426759c773709530b9bc0 https://doi.org/10.1161/circinterventions.113.000631

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Geometrical and Stress Analysis of Factors Associated With Stent Fracture After Melody Percutaneous Pulmonary Valve Implantation

Key Points

Study Design

Structured PICO

Main Result

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

Geometrical and Stress Analysis of Factors Associated With Stent Fracture After Melody Percutaneous Pulmonary Valve Implantation

Key Points

Study Design

Structured PICO

Main Result

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

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