Hello Reader,

Welcome to a new week. I hope you had a lovely weekend. First, I have to warn you that this is a rather long newsletter but do read as much as you can. I wanted to capture a lot of the ideas that have been going through my mind this week.

We started last week exploring what makes a good design of a stent. We will finish the second part of that reflection this week. I will also share some behind the scenes content as well as reflection on a quote for the week. Here are the break down of the newsletter content today:

1. Technical Reflection: Markers of a Good stent design - Part 2
2. Behind the Scenes at CM Videos: Reflection on a Unique Video
3. Quote of the Week: Creativity Conduits and Jon Gordon

Let us get into the content!

Technical Reflections

Markers of a good stent design: Part 2

Previously, we identified a stent in the following way:

We established the following as two markers of a good stent namely:

If you want to read about that first part, then click this link: Markers of a good stent design: Part 1. Let us look at two other markers of a good stent.

Foreshortening

This parameter is comparable to the elastic (radial) recoil parameter described above. While the elastic recoil focuses on diameter, the foreshortening term is measured along the length of the stent. It is therefore the ratio of the difference between expanded and recoiled lengths with respect to the expanded length. In other words, it describes the phenomenon in which a stent, when deployed within a blood vessel or anatomical passage way, appears shorter than its actual length. The extent to which this is manifested is called foreshortening.

As with other previously described parameters, foreshortening is also expressed in percentages and results from a lot of factors some of which are: the deployment process of the stent, the material properties, the stent design, and so on. Significant foreshortening will impose excessive shear stress on the walls of the blood vessel or anatomical passage way and hence leads to arterial damager. Typical acceptable values of foreshortening are between 5% and 10%.

If you are interested in learning how to numerically determine this value from a computational assessment of a stent, then watch this video from the CM Videos YouTube channel and please search for stent videos.

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Dogboning Index

When a stent is deployed, it should naturally expand concentrically so that every part of the stent expands homogeneously so that the scaffolding of the blood vessel or anatomical passage way will be uniformly distributed. Unfortunately, this is not always the case due to end-effects as the inflating pressure acting on the stent will often lead to the ends of the stent flaring outwards in a manner that resembles a dogbone shape. This phenomenon is called dogboning and the ratio between the flared end diameters to the central diameter of the stents is called the dogboning index.

The presence of dogboning will always exist during stent deployment but a good stent design should minimize this index. If it is excessive, then there is complications during stent deployment arising in: incomplete stent coverage, vessel damage (from the flared ends poking vessel walls), malapposition (poor contact with the vessel wall) and disruption of blood flow. All these will have the cumulative effect of leading to restenosis and thrombosis: two unwelcome complications of stent management of coronary artery diseases.

Acceptable percentages of dogboning index are ideally limited to 10%. The stent deployment mechanism (balloon expansion) and stent design are crucial factors in creating dogboning index. As usual, if you want to learn how to determine numerically this parameter, then check this video from the CM Videos YouTube channel.

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Other Measures of Stent Design

Whilst the four parameters described above are the common markers of a good stent especially in terms of their structural integrity, there are other measures/markers of stent design that should also be considered and these include the following:

• Damage Assessment Index (DAI): This parameters assesses the strut-level mechanics of a stent to ensure that during the deployment none of it would have failed. It explores material failure of the stent material rather than structural failure of the whole assembly.
• Stent Prolapse index (SPI): This quantifies the degree of stent prolapse during deployment. Prolapse here refers to the phenomenon where the stent struts partially or fully embed into the vessel wall. It has a relationship to material and stent design properties of the stents.
• Stent flexibility and kink-resistance indices: Stents experience bending and torsional deformations during deployment as they travel through the blood vessel. Therefore, another measure of a good stent design is the stent flexibility and kink-resistance indices. The right material, capable of finite deformations, should be used during the design of stents.
• Radiopacity: This refers to a capacity of the stent to be sufficiently radiopaque to allow clear visibility under imaging techniques like fluoroscopy. If the stent is not radiopaque, it can be difficult for the surgeon to track its position during deployment and will influence the ability to position it correctly at the site of occlusion.
• Radial strength: For the restoration of patency of the vessel (at the site of the plaque) to be achieved, the stent must have the strength to actually open up the vessel. The Radial strength is an objective parameter that defines the capacity of a stent to be able to open up the vessel.

Conclusion

We have explored some of the parameters that a stent designer and researcher must be aware of when developing bespoke stents. This is going to be the more important as surgeons begin to demand more patient-specific healthcare delivery to patients which is known to lead to high recovery outcomes for the patients. The interest I have in the above is clearly from the computational modelling perspective. Here is a recent paper where the above were discussed in more depth, if you are interested in this.

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Behind the Scenes at CM Videos

Reflection on a Unique Video

I published the video shown below about 5 months ago. It was a response to my students who wanted help with designing posters as part of their Final Year Project work. So, there was nothing really special with the video and it had a functional purpose. So, why am I reflecting about it in this video.

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Here is a chart from YouTube that shows what has happened to the video 5 months after it was published.

Some of the conclusions which are very interesting are the following:

• The first 100 days of the video being published, the video only experience 587 views.
• For the next 69 days, the video has been viewed 4024 times.
• The video has achieved a watch time of 296.3 hours which is 246.3 hours more than what is typical for this channel. This indicates that the video is loved and watched for a long time by my audience.
• The video alone has contributed 41 subscribers to the channel with 39 of those audience coming in the last 69 days.
• The video has also generated a revenue of $18.37 during this time, which is good.

My thoughts: The lesson from the above is that a video has the potential of going viral (at least in the case of my channel even 100 days after it was first published. I have also learnt that beyond just publishing about computational modelling topics, there is an appetite in my audience for ancillary videos that can help them deal with issues associated with academic research i.e. in this case preparing a poster to use for a conference. It is certainly what I had suspected would be the case so the performance of this video has given me the confidence that when I make videos as the above, it will help my audience. Please let me know if this is the case from your end.

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Quote of the Week

Creativity Conduits and Jon Gordon

I am taking the quote for the week from a comment from Jon Gordon, who was speaking on The Think Media Podcast under the episode title: 256: Never Run out of Content Ideas Again and the quote goes as follows:

This is a podcast I listen to a lot because the host Sean Cannel is someone I look up to a lot in the content creation aspect of YouTube. He is a christian and has bible-based principles behind his advice on how to succeed in YouTube. Right from the start of my YouTube journey, I have been following him and enjoy his words of wisdom. His values align with mine too.

In this particular episode, his guest Mr Jon Gordon was describing how creators should never run out of content ideas. The particular quote expressed a philosophical idea that a content creator - like myself with my YouTube channel and newsletters - must see oneself as a Conduit of Creativity. What does that mean?

A conduit is a pipe. It channels fluid from one point (usually at a higher potential/altitude - the discharging station) to another end (lower potential - the receiving station). The way nature and God has designed humanity is that there are always creativity ideas all around us. Nature is replete with them. It is always there discharging into the cosmos. It is left for a conduit, a pipe, a channel, a receptacle to harness those discharged creative ideas, distil them and send them out to the recipient which is the world around.

Put simply, there are ideas all around you. You just have to be open to receive them. As soon as the idea hits, then write them down, note them as they may not be there again when you are ready to tap into them. As Jon advised and this is what I do, always carry a notepad with you (physical or virtual on your phone) where you store ideas as they come. When you are ready to distil the ideas into a form to release to your world, then start with those recorded ideas from your notepad. This is what a conduit of creativity does.

I will urge you to try the same in your careers. You might not be creating contents for YouTube or writing newsletters as I do, but in your research, you might want to also note ideas that come to you in the most inappropriate times. Note them down, even on a napkin, and then work on them. This way, you are a veritable conduit of creativity and your product will be in great demand by the world because you are here, in the world at this time, because there is something unique that nature and God has you planned to do here on earth.

I wish you a wonderful week and I will catch up with you again next time. Let me know in a reply of anything that pique's your interest in what I have shared in this and maybe the previous newsletter. Take care and God bless you.