As a commonly used medical device for cardiac interventional procedures, cardiac stents play an important role in the treatment of heart diseases. Firstly, cardiac stents can unclog blood vessels and reduce myocardial ischaemia and heart burden, and their appearance fills the gap of traditional treatment methods. Secondly, the manufacturing materials and surface roughness of cardiac stents are crucial to the therapeutic effect.

Below, Dr Yoshi will present an application example of Atometrics White Light Interferometer AM-7000 series measuring the surface roughness of a cardiac stent.

一、 What is a cardiac stent?

Cardiac stents, also called "coronary stents", are a commonly used medical device for cardiac interventions, generally used to treat acute myocardial infarction, exertional angina pectoris, unstable angina pectoris, tetralogy of Fallot, or other complex congenital heart disease, etc. For the patients, cardiac stents are able to unclog the blood vessels, dilate the narrowed blood vessels, improve the blood flow, and reduce the ischemia of the myocardium and the burden on the heart.

The emergence of cardiac stents has filled the gap of traditional treatment methods. In the past, the treatment of cardiovascular diseases mainly relied on medication and open surgery, but there are certain limitations: medication needs to be taken for a long period of time and has limited efficacy, and is prone to drug tolerance and side effects; while open surgery treatment is associated with greater surgical trauma and surgical risk, and a longer recovery period. In contrast, the emergence of cardiac stents provides patients with a more convenient, safe and effective treatment option. Firstly, cardiac stent has less surgical trauma, relatively faster recovery and fewer postoperative complications, which can greatly reduce patients' pain as well as recovery time; secondly, cardiac stent surgery has less risk, higher success rate and more stable treatment effect, which can effectively improve patients' quality of life.

Cardiac stents are mainly manufactured from stainless steel, cobalt chromium alloy or nickel titanium alloy. Among them, traditional cardiac stents are mainly simple metal mesh tubes, which can be selected and implanted according to the size and shape of the patient's blood vessels; there are also drug-coated cardiac stents, where the drugs on the coating can be released continuously to effectively prevent restenosis of blood vessels and thrombosis by inhibiting proliferation of the cells in the tubes, thus enhancing the long-term effect of the procedure.

二、Cardiac Stent Surface Roughness Measurement

There are strict requirements for the production of cardiac stents, in which the surface roughness of cardiac stents with Ra>10μm will affect the mechanical properties, biocompatibility and delivery mode of the interface between the stent and the organism, while 10nm<Ra<10μm will have less effect on the mechanical properties at the interface and more effect on the biocompatibility. Generally speaking, micron-level surface roughness facilitates cell adhesion, which is conducive to improving the biocompatibility of scaffold materials to a large extent. Different types and configurations of cardiac stents have different surface roughness requirements, and if the surface roughness does not meet the established requirements, there will be risks of puncturing blood vessels, affecting the passage of platelets, and so on, which will affect the therapeutic effect, and therefore the surface roughness of cardiac stents needs to be controlled.

Below is an example of an application using the Atometrics White Light Interferometer AM-7000 Series to measure the surface roughness of a cardiac stent:

Surface roughness measurement of the inner wall of cardiac stents

Surface roughness measurement of the outer wall of cardiac stents

Atometrics White Light Interferometer AM-7000 Series has sub-nanometre accuracy;

Highest RMS repeatability up to 0.002nm;

With piezoelectric ceramic devices, the highest scanning speed of 400μm/sec;

3200Hz plus the industry's first SST + GAT algorithm.

Can instantly complete the highest 5 million point cloud acquisition;

Covering international standard measurement tools commonly used in the market.

Highly efficient and easy to analyse 3D data, easy to deal with the applications of various industries.