The primary conduit for blood, known as the aorta, can weaken and rupture in a significant percentage of the population. Reinforcement of the weakened aorta can be achieved by placement of a lining device known as a stent, but that can also block conduits that branch from the aorta causing further problems. A team of researchers co-led by Mohammad Eslami, MD (pictured top), Professor of Surgery and Bioengineering, University of Pittsburgh, Director of Clinical Research, UPMC Division of Vascular Surgery, and Chief of Vascular Surgery, UPMC Mercy, and McGowan Institute for Regenerative Medicine affiliated faculty member David Vorp, PhD (pictured bottom), Associate Dean for Research, Swanson School of Engineering, University of Pittsburgh, John A. Swanson Professor of Bioengineering, Co-Director of the Center for Medical Innovation, and the Director of the Vascular Bioengineering Laboratory, are developing a new method to create holes in the stent, while within the patient, to allow passage of blood to branching conduits.
This 2-year project entitled “Endovascular Orifice Detection (EOrD) Device for In Situ Fenestration of Abdominal Aortic Aneurysm” has been funded by the National Heart, Lung, and Blood Institute. The abstract reads:
Abdominal aortic aneurysm (AAA) is a localized dilatation of the aorta and if left untreated may go on to rupture which is associated with a 90% mortality rate. This is the 15th leading cause of death in the United States with more than 15,000 deaths reported annually. When an aneurysm reaches the maximum diameter criteria (greater than 5.0 – 5.5 cm), clinicians will intervene with either open surgery or endovascular repair (EVAR). For complex AAA cases, a minimally invasive fenestrated EVAR (FEVAR) is preferred over high-risk open surgery, however, fenestrated stent-grafts extend past the visceral arteries (renal, superior mesenteric artery and celiac artery) and must be revascularized after deployment requiring the stent-graft to be prefabricated. Currently, there is only one FDA-approved fenestrated graft on the market, the Cook Zenith Graft, that requires additional imaging for fabrication with a 6 – 8 week delivery time, costs up to 3 times more than traditional EVAR stent-grafts, and can be technically challenging when passing guidewires through the orifices of the fenestrations. The objective of this project is to develop a medical device for endovascular orifice detection (EOrD) which will both locate visceral arteries and perform in situ fenestration. This device can then be applied in the cases of AAA, ascending aneurysms, and traumatic aortic injury. Preliminary in vitro experiments were performed to determine whether visceral arteries could be detected through chelated sheep blood and stent-graft material using infrared (IR) waves. A scaled-up sensor array was built using phototransistors along with an analog to digital converter to detect the reflected IR waves. Distinct signal responses were collected while sweeping the sensor array over the orifice of the visceral artery, confirming feasibility. After an orifice of the visceral artery is detected, we plan to create a fenestration using a low-powered laser or mechanical puncturing mechanism that simultaneously inserts a guidewire to deploy the bridging stents. Our initial EOrD prototype with the proposed approach will be delivered through a catheter sheath and tested for orifice detection, puncture, and guidewire insertion using realistic in vitro AAA phantoms and cadavers. Continuous feedback from our clinical experts will improve design iterations to develop a final prototype that is able to reliably and reproducibly perform in situ fenestration of stent-grafts to treat aortic aneurysms. With our novel device, we can improve patient healthcare and reduce overall costs associated with AAA repair.
Illustration: University of Pittsburgh Department of Surgery (Eslami)/McGowan Institute for Regenerative Medicine (Vorp)
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