Thermal conductivity and diffusivity of biomaterials measured with self-heated thermistors

Valvano, Jonathan W.; Cochran, Jennifer R.; Diller, Kenneth R.

doi:10.1007/bf00522151

Cited by 284 publications

(214 citation statements)

References 3 publications

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“…S5A). The ventricular wall of the rabbit heart has a nominal thickness h = 1.9 mm, thermal conductivity k = 0.512 W/m/K (44), and a thermal diffusivity α = 0.131 mm 2 /s (45). Computed variations in surface temperature are consistent with experimental findings over the entire time range (∼3 min) without parameter fitting (SI Appendix, Fig.…”

Section: Resultssupporting

confidence: 69%

Electronic sensor and actuator webs for large-area complex geometry cardiac mapping and therapy

Kim

Ghaffari

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

213

167

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Curved surfaces, complex geometries, and time-dynamic deformations of the heart create challenges in establishing intimate, nonconstraining interfaces between cardiac structures and medical devices or surgical tools, particularly over large areas. We constructed large area designs for diagnostic and therapeutic stretchable sensor and actuator webs that conformally wrap the epicardium, establishing robust contact without sutures, mechanical fixtures, tapes, or surgical adhesives. These multifunctional web devices exploit open, mesh layouts and mount on thin, bio-resorbable sheets of silk to facilitate handling in a way that yields, after dissolution, exceptionally low mechanical moduli and thicknesses. In vivo studies in rabbit and pig animal models demonstrate the effectiveness of these device webs for measuring and spatially mapping temperature, electrophysiological signals, strain, and physical contact in sheet and balloon-based systems that also have the potential to deliver energy to perform localized tissue ablation.flexible electronics | semiconductor nanomaterials | stretchable electronics | implantable biomedical devices | cardiac electrophysiology C ardiac arrhythmias occur in all component structures and 3D regions of the heart, resulting in significant challenges in diagnosis and treatment of precise anatomic targets (1). Many common arrhythmias, including atrial fibrillation and ventricular tachycardia, originate in endocardial substrates and then propagate in the transverse direction to affect epicardial regions (1, 2). Characterizing arrhythmogenic activity at specific regions of the heart is thus critical for establishing the basis for definitive therapies such as cardiac ablation (3). Advanced tools that offer sufficient spatial resolution (<1 mm) and intimate mechanical coupling with myocardial tissue, but without undue constraints on natural motions, would therefore be of great clinical importance (4-6). To date, cardiac ablation procedures have largely relied on point ablation catheters deployed in the endocardial space (1, 5, 7-9). Although successful in the treatment of simple arrhythmias originating in and around the pulmonary veins, these devices are poorly suited for treating complex arrhythmias, such as persistent atrial fibrillation (10-13), that arise from various sites inside the left atrium. Other classes of devices have demonstrated the utility of spatiotemporal voltage mapping using various modes of operation, including noninvasive surface mapping designs (14, 15), epicardial voltage-mapping "socks" (16-20), and endocardial contact and noncontact catheters, with densities approaching 64 electrodes (21-31). These solutions all exploit arrays of passive metal wirebased electrodes integrated on wearable vests and socks (14-20) or catheter systems (21-26) for mapping of complex arrhythmias. Building such mesh structures requires manual assembly and is only possible because the individual wires are millimeter scale in diameter and thus sufficiently large to be threaded to form a mesh.Fo...

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Section: Resultssupporting

confidence: 69%

Electronic sensor and actuator webs for large-area complex geometry cardiac mapping and therapy

Kim

Ghaffari

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

213

167

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“…We used the material properties required for solving the bioheat [ (1)] from the literature [9], [14], [15]. Table I summarizes the material properties included in our FEM models.…”

Section: B Materials Propertiesmentioning

confidence: 99%

Three-dimensional finite-element analyses for radio-frequency hepatic tumor ablation

Tungjitkusolmun

Staelin

Haemmerich

et al. 2002

IEEE Trans. Biomed. Eng.

296

184

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Abstract-Radio-frequency (RF) hepatic ablation, offers an alternative method for the treatment of hepatic malignancies. We employed finite-element method (FEM) analysis to determine tissue temperature distribution during RF hepatic ablation. We constructed three-dimensional (3-D) thermal-electrical FEM models consisting of a four-tine RF probe, hepatic tissue, and a large blood vessel (10-mm diameter) located at different locations. We simulated our FEM analyses under temperature-controlled (90 C) 8-min ablation. We also present a preliminary result from a simplified two-dimensional (2-D) FEM model that includes a bifurcated blood vessel. Lesion shapes created by the four-tine RF probe were mushroom-like, and were limited by the blood vessel. When the distance of the blood vessel was 5 mm from the nearest distal electrode 1) in the 3-D model, the maximum tissue temperature (hot spot) appeared next to electrods A. The location of the hot spot was adjacent to another electrode 2) on the opposite side when the blood vessel was 1 mm from electrode A. The temperature distribution in the 2-D model was highly nonuniform due to the presence of the bifurcated blood vessel. Underdosed areas might be present next to the blood vessel from which the tumor can regenerate.

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“…Water predominates as a major determinant of the thermal properties of most soft tissues but its influence may be less important in hard tissues such as bone and dental enamel. Also, fatty tissues such as subcutaneous tissue and fatty atheromatous plaques have significantly different thermal properties than water dominated tissues (Valvano, 1985).…”

Section: Laser and Tissue Parameters: General Considerationsmentioning

confidence: 99%

Pathologic Analysis of Photothermal and Photomechanical Effects of Laser–tissue Interactions

Thomsen

1991

Photochem & Photobiology

531

312

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Abstract-Pathologic analysis of the biologic effects and mechanisms of laser-tissue interactions requires correlation of the irradiation parameters with the biologic status and response of the target tissues over time. The photobiologic mechanisms of laser-induced tissue injury can be separated into three categories, photochemical, photothermal and photomechanical. Anatomic pathologic analysis of laser-induced lesions reveals alterations that represent either specific markers of the photobiologic mechanism or non-specific reactions to tissue injury. Repair, regeneration and wound healing of laser induced lesions appear to be non-specific responses to the type of tissue damage rather than the photobiologic mechanism producing the lesion.

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Thermal conductivity and diffusivity of biomaterials measured with self-heated thermistors

Cited by 284 publications

References 3 publications

Electronic sensor and actuator webs for large-area complex geometry cardiac mapping and therapy

Electronic sensor and actuator webs for large-area complex geometry cardiac mapping and therapy

Three-dimensional finite-element analyses for radio-frequency hepatic tumor ablation

Pathologic Analysis of Photothermal and Photomechanical Effects of Laser–tissue Interactions

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