Hemodynamic Performance of Self-expandable Transcatheter Aortic Valve Replacement Systems During Valve Deployment: An Interview With Alberto Alperi, MD, PhD

Dr. Alberto Alperi shares background and insights on his paper, “Hemodynamic Performance of Self-expandable Transcatheter Aortic Valve Replacement Systems During Valve Deployment.” Read the article here.

Transcript:

My name is Dr. Alperi. I’m an interventional cardiologist in the University Hospital of Asturias in Oviedo, Spain. I'm the first author of the manuscript entitled "Hemodynamic Performance of Self-Expandable Transcatheter Aortic Valve Replacement Systems During Valve Deployment” for the Journal of Invasive Cardiology.

00:35: What inspired your group to initiate this study?

Actually, in our center in the University Hospital of Asturias, we have great experience with self -expandable devices. More than 80% of our TAVR implantations are performed with self-expandable systems. And over the years, we have observed with the Evolut, with the Medtronic platform, that certain patients remain quite hemodynamically unstable once the valve was partially open, when it was yet recapturable, what we usually call the two-thirds of valve opening. And we did not know the reason why this happened, because it was supposed to perform perfectly, the leaflets to open normally, and we did not know how these patients remain a little bit unstable or hypertensive during valve deployment when the valve was yet recapturable. And this may have an impact on clinical practice, because as we know nowadays, we have to evaluate device depth, depth of implantation, because it has an impact on conduction disturbances after TAVR and this is very significant clinically.

So, we have to evaluate the implantation depth in regards to the non-coronary sinus, especially in the Evolut platform, and if the patient is unstable and if the patient is not tolerating properly the valve hemodynamics at that point, we cannot perform this evaluation. So, we took advantage of our participation in the SAFE-TAVI trial, which is a trial that evaluated the effectiveness and the safety of the SavvyWire in TAVR procedures to perform this study. Just to remind, the SavvyWire is a high -support guide wire that incorporates like a sensor very close to the distal tip that enables pressure monitoring during the structural cardiac procedures. So this allow us to perform our study.

03:05: Why did you choose to focus on these two devices in particular?

Well, the first reason for that is very simple, it’s logistics, because in our center, those are the two self -expandable devices that we use in clinical practice. And secondly, it does not make, let's say sense, to perform these sorts of analysis for balloon-expandable devices because balloon-expandable devices are deployed very quickly and there's no hemodynamics during that point between the left ventricle and the aorta. There's just rapid pacing, the balloon inflates and then the valve is deployed. On the contrary, self-expandable devices are implanted in several steps and the patient has to tolerate the steps in order to evaluate and to analyze how the implantation is going, how the position and the height of the valve, if we are happy with it or not. So our idea was to evaluate only self-expandable systems.

This analysis might be very interesting also for other self-expandable platforms like Navitor, but in our center we use exclusively Evolut and ACURATE Neo self-expandable devices.

04:40: Were you surprised by any of the results?

Honestly, yes, we were very surprised. We expected the Evolut platform to perform once it was partially implanted. It's two-thirds of implantation when the valve is yet recapturable and repositionable, but it should be functional. We expected to observe almost no gradient between the left ventricle and the aorta at that time point, and on the contrary, we observed that the gradients or both mean and peak-to-peak gradients were very similar to what the patient had before the implantation, before the initiation of the type of deployment. So it was like if the patient still had a severe aortic stenosis, and besides probably concomitant with a certain degree of aortic regurgitation, because at that point the valve was not fully open and the force that the nitinol frame was doing against the aortic cavity was probably was not enough to avoid all aortic regurgitation. So I think those two facts all together are the main points that may lead to a hemodynamic deterioration in a subset of patients at this time point when we evaluate implantation height, valve position, etc.

On the contrary, we observed for the ACURATE Neo platform that is deployed in 2 different steps, top-down deployment, that after the expansion of the upper crown, there was almost no gradient between the left ventricle and the so aorta, at this point the valve was completely functional and the hemodynamic tolerance was very, very good. It's true that only very, very small and tiny adjustments of the valve positioning can be performed with this platform at this point after the upper crown deployment, but you can do it very comfortably because the patient will remain very stable because there's almost no gradient between the 2 chambers, the left ventricle and the aorta after this point.

06:56: Is there anything you’d like to study further based on these data?

We are very interested in the subject of, for example, valve durability, which is a hot topic in TAVR nowadays. And we think that probably valve hemodynamics, hemodynamics immediately after TAVR deployment may play a role in valve durability, structural valve deterioration. And we are trying to evaluate also these hypotheses that the greater degree of residual gradients can lead to, let's say, a more rapid valve deterioration, but we have to prove it and we are trying to work this out.

Also this different guide wire that has seen light lately, this SavvyWire, might be very useful in valve -in-valve deployments because we know that there's always a certain degree of residual gradient between the left ventricle and the aorta after valve-in-valve procedures, especially when we perform it in small aortic bioprostheses. And this guide wire will allow us to evaluate in detail the residual gradients and to optimize the results when one is needed. So those 2 points, those 2 main aspects, I think we're going to perform more studies, we're going to gather more data, and will be fields to work in in the near future, that's my guess.

08:42: What do you hope physicians take away from this study?

First of all, the main point, main message is that when we are implanting the Evolut device, the transcatheter valve is not yet completely functional at the last point of unsheathing before it's no longer recapturable-it's functional but only partially. There's yet a very important residual or very important gradient between the left ventricle and the aorta, very close or almost similar to that that the patient had before implantation, so with severe aortic stenosis.

On the contrary, when the valve is deployed, that is 90%, so it's no longer recapturable, but the upper part of the nitinol frame is yet within the sheath. At this point, the valve is very functional, it’s almost very close to what we have observed after the procedure, after the valve is fully implanted. So, at this point you can unsheath and you can finish your implantation very comfortably, very slowly to avoid unexpected release of the tension of the valve. So, you have to evaluate your position quickly when the valve is yet recapturable, but then you can unsheath very slowly because the valve is getting more functional and the gradient diminishes as the valve is being opened.

For the ACURATE platform, on the contrary, once you have done the upper crown deployment, the valve is very functional, there's almost no gradient between the LV and the aorta and you can adjust your position without any rush.

10:35: Is there anything else you’d like to share with our audience?

Well, I think that that's all. I'm very honored to be in this interview. I have spoken on behalf of all the coauthor of the study and especially Dr. Moris and Dr. Avanzas who have shared with me the leadership of this study of the SAFE-TAVI trial and I'm very happy for sharing this information and this interview with you. Thank you very much.