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John Ormiston

MBChB, FRACP, FRACR, FCSANZ, FAPSIC, FACC, FRCP, ONZM Medical Director Mercy Angiography

Professor, University of Auckland School of Medicine Interventional Cardiologist Auckland New Zealand

10 Mins Sat afternoon after 2pm

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Cardiologists, scientists engineers met for 3.5 hours yesterday to discuss creating a consensus document for bench testing for coronary bifurcations Ormiston, Lefevre, Louvard, Stankovic, Chatzizisis Foin, Mortier, Wentzel Murasato, Hikichi, Iwasaki Mickley, Eckermann, Shehey, Cook, Bliss, Davis Medrano-Garcia, Beier Kassab and Finet could not attend but had provided critical feed back on draft documents .

Why bench test devices in bifurcations •  To understand how devices work, their strengths and weaknesses, and to

test design iterations and procedural changes. •  To shed light on a clinical problem (eg longitudinal distortion), to generate

solutions for the problem (additional connectors=promus premier), and to determine whether the solution works.

•  Bench studies may raise concerns and alter clinical practice •  Bench studies may produce surprises •  Bench studies may be used to validate computational modelling •  Teaching of interventional techniques on the bench is becoming more

important •  Our testing must be independent– some manufacturers may select tests

that show their product in the best light

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•  US Food and Drug Administration (FDA) and the International Organization for Standardization (ISO) provide extensive guidance for general assessment of stents but almost none specifically for bifurcations

•  Our proposed EBC guidance document is intended to assist bench assessment of stents in coronary bifurcations. It has been generated by clinicians, scientists and engineers and will provide general principles rather than be a step-by-step manual.

•  Consistent nomenclature is proposed eg naming of angles between branches. Even at EBC at least two naming systems are operating

Clinical need and endpoints •  It is important to ensure that the unmet clinical need is identified and that it

is clinically relevant. Ensure that endpoints are clinically important.

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Finet “The future of bifurcation models lies with anatomically accuracy, obedience to the scaling laws and construction from materials with an appropriate Young’s Modulus”. They should allow imaging of deployed stents. A small group has been assigned the task of reviewing the bifurcation literature on coronary artery diameters, angles, lengths. Another group will report back on materials and phantom construction

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•  In designing a bench model, it is important to reproduce bifurcation geometries consistent with nature.

•  It is well known that the geometry of a coronary bifurcation obeys a set of geometric rules known as scaling laws (Murray, Huo Kassab, Finet).

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Pau Medrano-Gracia has constructed an Atlas of coronary bifurcations derived from 300 normal CT angiograms. Consensus document will in the first instance develop recommendations for phantom construction based on normal anatomy

Constructed for all major bifurcations LAD/diag, Cx/Om etc

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There are some large anatomical libraries eg Kassab’s and Medtronic’s in Minnesota J Wentzel and colleagues have published a literature review of angles, diams etc.

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Finet. We also have to make sure that the bench model walls meet specific objectives such as having a Young’s modulus (a mechanical property of linear elastic solid materials measuring the force (per unit area) needed to stretch (or compress) a material sample. The higher the Young’s modulus the more rigid the material) matching the mechanical properties of a fibrocellular coronary arterial wall

A sub-committee will look into practical aspects of phantom manufacture eg casting, 3D printing, tubing Mindful of imaging needs

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We hope to meet at TCT.

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