Dr. M. Piazza: "Standarized PMEG may allow a more reliable understanding on safety and efficacy"

Today in our 'Scrub with the Experts' section, we have Dr. Michele Piazza. Dr. Piazza works as a vascular surgeon and associate professor at the Padua Hospital in Italy, and he is a global leader in complex aortic therapy, with numerous publications and participation in multicenter registries concerning aortic pathology.

Dr. Piazza recently published in 'JVS Cases, Innovations, and Techniques' a model of standardized modification for complex endovascular treatment of the thoracoabdominal aorta.

Javier Rio: First of all, congratulations on your publication regarding the standardization of PMEG. What do you believe are the benefits of carrying out stent-graft modifications in a standardized way?

Michele Piazza: Thanks Javier. Even if PMEG have demonstrated world-wide excellent outcomes especially for complex AAA, the major limitation is lack of standardization and quality control.

Developing a 4 fenestrated standardized PMEG graft, that can be performed in multiple centers with the same approach, may allow in the near future for a more reliable understanding on safety and efficacy of this specific method of endo repair for non deferrable aortic aneurysms.

J.R.: Since you began modifying stent-grafts, has your technique changed significantly? What have you learned through experience?

M.P.: I started my approach to PMEG only in urgent cases with simple single fenestration or scallop. Over time, increasing knowledge of different grafts characteristics, I increased progressively the complexity of modification and have developed a single method for 4 fen in case of iuxta-pararenal AAA and type IV TAAA; this primarily to have the possibility to treat with a single graft a large range of complex AAA with low biases related to different approaches to modification.

What I learned, is that again, other that have a good and safe technique for modification, patient anatomic selection represent a major point for success.

J.R.: Considering the entire process (planning-modification-implantation), which steps do you consider the most important to achieve good outcomes?

M.P.: Planning is a crucial and very complex point for standardized 4 fen graft. Technical success and long-term efficacy is directly related to perfect alignment of the fenestration to the target vessel ostium.

In this regard, we are developing a simple and fast method for standardized measurements at the preoperative CT angiogram and fenestration allocation into the graft, that is tapered for each patient specific anatomy.

J.R.: What is your preferred stent-graft for modification, and what advantage does it offer over others?

M.P.: The thoracic Valiant Captiva is in my opinion the graft of choice for 4 fen PMEG.

1- Large distances between struts (between 18 and 25 mm depending on graft diameter) for easy fen allocation within fabric space

2- easy to resheat

3- posterior constraining wire with no need for fabric puncture

4- Nitinol stents with high conformability to diameter mismatch between the supraceliac aorta proximal sealing area and the pararenal aorta.

J.R.: Your standardized technique modifies a straight tube graft. Under what circumstances would you consider modifying a bifurcated stent-graft?

M.P.: The major difference between a bifurcated graft and a tube to modify is:

1- in the bifurcated device is difficult to have a constraining wire for graft rotation

2- also the length of the main body in bifurcated devices, at today, is generally short to obtain a safe and long sealing length and incorporate multiple vessels.

For these reasons I generally use a bifurcated device for a single lowest renal fenestration in case of iuxtarenal (4 -8mm) aneurysm with different level renals take off.

In case of iuxtarenal (0 -4 mm),pararenal and Type IV I go directly to 4 fen graft with a single tube graft followed by a distal bifurcated device as is general hystorical rule today with CMD.

J.R.: If you could modify something about conventional stent-grafts to improve or facilitate their modification, what would it be?

M.P.: To have dedicated tools for rounded hole creation in the fabric, rounded reinforcement, and preexisting constraining wire in the posterior wall.

J.R.: To conclude the interview, do you believe it is feasible, in the short to medium term, to reach a scenario where we have a stent-graft in which the possibility of modification by the physician is included in the instructions for use?"

MP. Nowadays, strong efforts comes from physicians and companies in this direction; regulatory issues for safety and efficacy of these procedures need to be addressed and will require additional time. As experts in the field, our major role is to define clear indication on patient anatomical and clinical selection for adequate treatment.