Biomedical polymers — For vascular grafts or heart bypass applications, which tubing materials are commonly used as substitutes for human blood vessels?

Introduction / Context:
Vascular grafts require materials with biocompatibility, chemical stability, suitable porosity or surface for tissue integration, and appropriate mechanical compliance. Historically, PTFE (Teflon) and PET (Dacron) have been widely used for such grafts and bypass conduits.

Given Data / Assumptions:

• Application: blood vessel substitutes (arterial grafts, bypass).
• Material choices include common commodity plastics and established biomedical polymers.
• We seek clinically used, well-documented options.

Concept / Approach:
Expanded PTFE (ePTFE) and woven/knitted PET (Dacron) provide the necessary strength, porosity, and biostability. They have long clinical histories, unlike PVC, PS, or PE in this specific role. Surface modifications may be applied to improve hemocompatibility.

Step-by-Step Solution:
Identify established graft materials: PTFE (Teflon) and PET (Dacron).Exclude commodity plastics with poor hemocompatibility or mechanical mismatch.Therefore, select PTFE/PET as the correct answer.

Verification / Alternative check:
Surgical literature and device registries document PTFE and PET grafts across decades of practice.

Why Other Options Are Wrong:

• PVC, PE, PS, PP: although used in medical devices and tubing, they are not standard for permanent vascular grafts.

Common Pitfalls:
Confusing general medical tubing materials with implantable vascular graft materials; overlooking the importance of long-term hemocompatibility.

Final Answer:
Teflon (PTFE) / Dacron (PET)