Stresses from flexure in composite helical implantable leads

Meagher, J.M.; Altman, Peter

doi:10.1016/s1350-4533(96)00022-7

Cited by 11 publications

(15 citation statements)

References 3 publications

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“…The tensile force resulted from the deflection is given by:

P = \frac{δ G d^{4}}{64 K_{2} {false(R_{0} false)}^{3} n}

The normal stress, σ, and torsional stress, τ, on the conductor wire circular cross-section are:

σ = \frac{32 P R sin α}{π d^{3}}

τ = \frac{16 P R cos α}{π d^{3}}

For the bending load on the close-coiled helical spring, Meaghter et al has developed an analytic model from a strength-of-materials approach proposed by Durelli [8–10]. The accuracy of the model was verified with mechanical bending tests of springs and finite element analysis [8].…”

Section: Methodsmentioning

confidence: 99%

“…The accuracy of the model was verified with mechanical bending tests of springs and finite element analysis [8]. …”

Section: Methodsmentioning

confidence: 99%

“…The bending radius of curvature can be anticipated from the parametric function of the 3D cubic spline (see section above). Given a coil of known rigidity, β, and bending radius ρ, the bending moment is calculated from ( D = coil diameter, d = wire diameter, r = wire radius) [8]:

\frac{1}{ρ} = \frac{M}{β} = \frac{2 E I G J cos α \frac{L}{n}}{D π G J false[1 + {false(sin α false)}^{2} false] + E I {false(cos α false)}^{2}}

Rearrange the equation:

M = \frac{β}{ρ} = \frac{D π G J false[1 + {false(sin α false)}^{2} + E I {false(cos α false)}^{2}}{2 E I G J cos α \frac{L}{n}}

The torsion T θ can be calculated. M res is the integration of the M R and M z

M_{r e s} = \sqrt{{(M cos θ)}^{2} + {(M sin θ sin α)}^{2}}

For the wire with circular cross-section, the curvature stress concentration factor, K , is a function of distance from wire axis, d i, where 0< d i < d .…”

Section: Methodsmentioning

confidence: 99%

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Analytical Modeling for Computing Lead Stress in a Novel Epicardial Micropacemaker

Zhou

Bar‐Cohen

Peck

et al. 2017

Cardiovasc Eng Tech

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Purposes Implantation and maintenance of a permanent cardiac pacing system in children remains challenging due to small patient size, congenital heart defects and somatic growth. We are developing a novel epicardial micropacemaker for children that can be implanted on the epicardium within the pericardial space via a minimally–invasive technique. The key design configurations include a novel open-coiled lead in which living tissue replaces the usual polymeric support for the coiled conductor. To better understand and be able to predict the behavior of the implanted lead, we performed a radiographic image-based modeling study on a chronic animal test. Methods We report a pilot study in which two mechanical dummy pacemakers with epicardial leads were implanted into an adult pig model via a minimally invasive approach. Fluoroscopy was obtained on the animal on Post-Operative Days #9, #35 and #56 (necropsy). We then constructed an analytic model to estimate the in vivo stress conditions on the open-coil lead based on the analysis of orthogonal biplane radiographic images. Results We obtained geometric deformation data of the implanted lead including elongation magnitudes and bending radii from sequenced films of cardiac motion cycles. The lead stress distribution was investigated on each film frame and the point of maximum stress (Mean Stress= 531.4 MPa; Alternating Stress = ± 216.4 MPa) was consistently where one of the leads exited the pericardial space, a deployment that we expected to be unfavorable. Conclusions These results suggest the modeling approach can provide a basis for further design optimization. More animal tests and modeling will be needed to validate whether the novel lead design could meet the requirements to withstand ~200 million cardiac motion cycles over 5 years.

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“…The tensile force resulted from the deflection is given by:

P = \frac{δ G d^{4}}{64 K_{2} {false(R_{0} false)}^{3} n}

The normal stress, σ, and torsional stress, τ, on the conductor wire circular cross-section are:

σ = \frac{32 P R sin α}{π d^{3}}

τ = \frac{16 P R cos α}{π d^{3}}

Section: Methodsmentioning

confidence: 99%

“…The accuracy of the model was verified with mechanical bending tests of springs and finite element analysis [8]. …”

Section: Methodsmentioning

confidence: 99%

\frac{1}{ρ} = \frac{M}{β} = \frac{2 E I G J cos α \frac{L}{n}}{D π G J false[1 + {false(sin α false)}^{2} false] + E I {false(cos α false)}^{2}}

Rearrange the equation:

M = \frac{β}{ρ} = \frac{D π G J false[1 + {false(sin α false)}^{2} + E I {false(cos α false)}^{2}}{2 E I G J cos α \frac{L}{n}}

The torsion T θ can be calculated. M res is the integration of the M R and M z

M_{r e s} = \sqrt{{(M cos θ)}^{2} + {(M sin θ sin α)}^{2}}

For the wire with circular cross-section, the curvature stress concentration factor, K , is a function of distance from wire axis, d i, where 0< d i < d .…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Analytical Modeling for Computing Lead Stress in a Novel Epicardial Micropacemaker

Zhou

Bar‐Cohen

Peck

et al. 2017

Cardiovasc Eng Tech

View full text Add to dashboard Cite

show abstract

“…Meagher and Altman [28] presented a theoretical model for calculating the general stress state in helical implantable leads under bending. The analytical work was based on the previous literature on stress analysis of coil springs.…”

Section: Introductionmentioning

confidence: 99%

In Vivo Stress Analysis of a Pacing Lead From an Angiographic Sequence

Liu

Wang

Yang

et al. 2011

Journal of Biomechanical Engineering

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In this paper, a method is presented to analyze the mechanical stress distribution in a pacing lead based on a sequence of paired 2D angiographic images. The 3D positions and geometrical shapes of an implanted pacemaker lead throughout the cardiac cycle were generated using a previously validated 3D modeling technique. Based on the Frenet-Serret formulas, the kinematic property of the lead was derived and characterized. The distribution of curvature and twist angle per unit length in the pacing lead was calculated from a finite difference method, which enabled a rapid and effective computation of the mechanical stress in the pacing lead. The analytical solution of the helix deformation geometry was used to evaluate the accuracy of the proposed numerical method, and an excellent agreement in curvature, twist angle, and stresses was achieved. As demonstrated in the example, the proposed technique can be used to analyze the complex movement and deformation of the implanted pacing lead in vivo. The information can facilitate the future development of pacing leads.

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“…2 The pitch angle is related to the pitch in the following way: tan(␥) ϭ p/D 2 . The equation itself may appear to be complicated, but bending stiffness is proportional to diameter (D 1 ).…”

mentioning

confidence: 99%

Softness of Endovascular Coils: Fig 1.

Jou¹

2010

AJNR Am J Neuroradiol

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Stresses from flexure in composite helical implantable leads

Cited by 11 publications

References 3 publications

Analytical Modeling for Computing Lead Stress in a Novel Epicardial Micropacemaker

Analytical Modeling for Computing Lead Stress in a Novel Epicardial Micropacemaker

In Vivo Stress Analysis of a Pacing Lead From an Angiographic Sequence

Softness of Endovascular Coils: Fig 1.

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