Lecture 6 (Case Study)

Question 1

Guidewires

Answer 1

• used for therapeutic and interventional procedures
• facilitate placement of balloons and stents during percutaneous interventional procedures
• typically stainless steel or nitinol
• in class, went over a guidance document describing guidewires intended for use in the coronary vasculature, peripheral vasculature, and neurovasculature

Question 2

Device Description

Answer 2

• device components (function of all pieces, basic operation, identify unique features, sizing, etc.)
• engineering drawing(s) of the device (with all dimensions, can also provide photograph)
• technological characteristics, including specifications
• materials (identify each along with its contact duration)

Question 3

Predicate Comparison

Answer 3

• how is the device similar and different from the predicate (can utilize side by side comparisons)
• explain intended environment/use, indications for use statement, unique features compared to predicate, and why these differences do not raise questions of safety and effectiveness

Question 4

Biocompatibility

Answer 4

• do materials induce biological responses that are harmful
• determine biocompatibility of all patient-contacting materials present
• if identical in composition, can reference previous literature
• otherwise conduct/provide risk assessment, and explain how the risks will be mitigated

Question 5

Aspects of biocompatibility

Answer 5

• cytotoxicity (cell culturing, like death/growth/behavior)
• sensitization (skin/other tissues sensitivity to components responding with inflammatory immune response)
• irritation (skin, eye, and mucous membrane damage)
• hemocompatibility (blood-contacting device effects on blood)
• acute systemic toxicity (potential absorption of toxic leachables and degradation products)
• chronic toxicity (major period of life-span of animal)
• implantation tests (local effects on tissue)
• genotoxicity (gene mutation or DNA toxicities)
• carcinogenicity (cancer inducing?)

Question 6

Sterility

Answer 6

• needed to minimize infections and related complications
• methods include steam, dry heat, ethylene oxide (EtO), and gamma ray

Question 7

Pyrogenicity

Answer 7

• risk of raised temperature reaction due to endotoxins or leached chemicals

Question 8

Shelf Life and Packaging

Answer 8

• conducted to support the proposed expiration date by evaluating package integrity and any changes to device performance
• can repeat bench-top tests on elements potentially affected by aging

Question 9

Non-Clinical Bench Testing

Answer 9

• evaluate material/performance characteristics of your final sterilized device
• use the WORST-CASE design for each test
• prove substantial equivalence

Question 10

Bench Testing examples

Answer 10

• preconditioning (test-dependent, trying to simulate necessary conditions)
• simulated use model (how does the product work in action)
• tensile strength and tip pull for guidewire (test predicate device to set the acceptance criteria)
• torque strength and torqueability
• coating integrity and lubricity
• corrosion and kink resistance
• tip flexibility, radiopacity

Question 11

Clinical Performance Testing

Answer 11

• requested when device may be used in complex clinical scenarios, engineering testing raised issues, indications for use are novel, or is a new technology