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Clinica's Medtech Ventures: Sonavex, Inc.

This article was originally published in Clinica

Executive Summary

Specialty area(s): Ultrasound to detect postoperative thrombosis
Based in: Baltimore, Maryland, US
Founded in: 2013
No. of employees: 3
Total investment received to date: $1m
Investors: Abell Foundation; Blue Jay Syndicate; Angel investors

Since the advent of free-flap surgery more than 30 years ago, whereby autologous soft tissue is moved, and arteries or veins reconnected, the risk of a blood clot forming in the newly connected vessels during the postoperative period is ever-present. EchoSure from Sonavex designed to provide reliable, early detection of thrombosis, coupled with an excellent device safety profile, by detecting changes in blood flow using Doppler ultrasound. This will provide the earliest possible sign of a blood clot after surgery, according to company CEO David Narrow. EchoSure consists of two components: an echogenic marker implanted intraoperatively and software loaded onto the company’s Doppler ultrasound machine for postop monitoring. The clinician uses the ultrasound probe to scan the surgical site, whereas the software provides precise navigation and processes the data.

“No one has been able to figure out a way to prevent these clots from occurring, but everyone recognizes that early detection enables a successful salvage of the procedure,” Narrow says. “Our tool should provide surgeons exactly what they need to hypothetically prevent all these failures they are experiencing.”

Every year in the US, 550,000 patients undergo either reconstructive, transplant or vascular surgery, for a potential annual market opportunity of about $1bn for EchoSure.

Sonavex co-founders Narrow and Devin O’Brien Coon first met in 2012 at Johns Hopkins University, where they were in classes together as master’s degree students in biomedical engineering. Coon, already a plastic reconstructive surgeon at the university, and Narrow decided to find a solution to thrombosis that Coon encountered on a routine basis. The two entrepreneurs believed that ultrasound was the key because it is used in a wide variety of vascular applications. However, image-analysis expertise was required, so they turned to third co-founder Jerry Prince, a professor of electrical and computer engineering at Johns Hopkins with decades of experience in medical image processing.

Two challenges of developing EchoSure were optimizing the visibility of the implant, and software that was robust enough so non-skilled sonographers could easily use the system to generate reliable information. “Successful imaging requires a marker,” Narrow notes. “Without an implant, you are unable to identify the proper blood vessels and the position where the clot will form.” Further, the natural anatomical positioning of the vessels after these surgeries does not enable accurate data collection. “Our implant not only enables the clinician to find the proper location, but ensures sufficiently accurate data,” Narrow says.

Narrow, who earned his master’s degree in 2013, served as a consultant for Health Advances LLC from 2013 to 2014, and co-founded MonoMano Cycling Inc. (adaptive cycling equipment for those with physical limitations) in 2012. Prince co-founded Diagnosoft Inc. (cardiac MRI) in 2002.

Sonavex has two pending (none issued) patents. The company declines to say if it has a licensing agreement or will be sharing royalties and/or revenues with another entity.

EchoMark is the name of the bioabsorbable implant that is placed at the time of surgery to enable localization of the surgical site postoperatively. The marker, which is about the size of a human thumb, is sutured into the soft-tissue bed below the blood vessels, immediately prior to standard closing of the patient. Most surgical procedures will require only one implant, with the exception of certain transplant cases that may require two. The marker takes about a year to completely absorb.

The other component, EchoFind software, is first employed by the surgeon right after surgery to navigate to the surgical site so the region can be scanned with Doppler ultrasound for about two minutes to collect the appropriate data. “We monitor blood flow across one specific position – where the blood vessels are connected [the anastomosis],” Narrow explains. “The marker highlights the vessels on the ultrasound screen.” The software then processes the data and shows the clinician visually and quantitatively the volumetric flow rate in the vessels, so that the clinician can flag any abnormal blood flow. Information appears on the monitor as a number and a plot over time. EchoSure has been shown to successfully detect changes in blood flow in animal studies.

During the first 24 hours after surgery, patients are monitored hourly with EchoFind, then every other hour on the second day and once every four hours on the third day. “If a clot forms, it will happen within the first 72 hours,” Narrow states. After the first scan, immediately after surgery, nurses without specialized sonographic training can take over, “which is a huge value add,” he says.

Narrow notes that up to 15% of patients develop thrombosis, for which there is an established surgical intervention to quickly remove the blood clot. In cases where thrombosis is not detected and treated in a timely manner, the affected tissue becomes necrotic and must eventually be removed surgically. There are also two or three follow-on procedures to restore healthy tissue and up to an additional one-month hospitalization to recover, “for which the hospital has to pay out-of-pocket for all these costs, which range between $57,000 and $500,000 per patient,” Narrow says.

Adds surgeon Coon, “When these failures occur, it is a drawn-out disaster for patients and surgeons both, which is why it carries so much impact for us as an unsolved clinical problem.”

Competitor ViOptix Inc. (T.Ox) uses a near-infrared spectroscopy skin oxygen sensor (a pulse oximeter) for monitoring. However, the external pad placed on the skin “is unreliable because oxygen levels fluctuate after surgery, for reasons other than a blood clot,” Narrow conveys. This device also requires near-complete occlusion before detecting a problem, “which obviously delays the time for intervention.” Moreover, T.Ox is limited to a subset of target surgeries because of depth constraints. A second rival, Cook Group Inc.’s Cook Medical (Cook-Swartz Doppler Probe Flow), evaluates blood flow via an audible noise. The device is an internal silicone cuff that wraps around the delicate vessel. “But there are serious safety risks with the probe because the cuff leads to a wire that extends from the body and is connected to a unit that processes the signal,” Narrow explains. “Any time the patient moves or the wire pulls from box repositioning, excessive force is applied to the very delicate vessel.”

510(k) and CE mark are being pursued concurrently and should be in place within the next two years. Once launched, EchoSure reimbursement will come from a bundled payment for an inpatient procedure.

The $1m Sonavex has raised to date represents multiple grants, including one from the National Institutes of Health last spring and one from the National Science Foundation last summer. Before that, the company received two separate grants from Maryland Technology Development Corp., one in 2013 and the other in late 2014, as well as a Coulter Translational Research Award from Johns Hopkins University in 2014. In addition, a seed round funded by Abell Foundation, Blue Jay Syndicate and angel investors concluded last summer. A Series A in the range of $1-3m should initiate later this year, targeting early-stage medtech investors.

Sonavex has partnered with an ultrasound company for OEM production. The most likely exit strategy is acquisition by a surgical or imaging company. The start-up also has two other ultrasound-related products in development, both in the perioperative space.

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