Five Questions and an Elevator Pitch: Circardium

1. What is the need that your project seeks to address?

Pedro: We are focused on hypoplastic left heart syndrome [HLHS], a rare congenital heart defect in which the left side of a baby's heart is underdeveloped. Multiple surgeries are required to treat the condition, in many cases as a bridge to transplant, starting soon after birth. These challenging surgeries are focused on creating novel cardiovascular circuitry more akin to normal blood flow. The ultimate goal is to allow the right ventricle to supply both the lungs and body with oxygenated blood, bypassing the poorly functioning left side of the heart. Between the first and second operations, which are done approximately four months apart, oxygenated and oxygen-poor blood intermix, creating a need to measure and monitor the Qp/Qs ratio, or the ratio of pulmonary to systemic blood flow. Currently, there isn't a straightforward method for measuring this critical value accurately or easily. We hope to develop a better way to measure blood oxygenation to help providers make the best care decisions and improve outcomes for newborns with this life-threatening condition.

Zofia: The current standard for Qp/Qs measurement is an invasive catheterization requiring general anesthesia. Because of this, the catheter-based Qp/Qs measurements may not be generalizable. However, this is one of the most important values that physicians assess to make care decisions. We’re finding a way to measure blood flow more accurately without the use of anesthesia.

Khanh: These complex cases tend to have a large team of care providers, and there is sometimes disagreement because of the infrequency and subjectivity of Qp/Qs estimation between invasive measurements. This can lead to inconsistent care decisions, which is not ideal for ensuring that these babies are experiencing optimal blood flow following the first surgery

Dylan: Our physician mentor, Dr. Ritu Asija, who is a pediatric cardiologist, works with critically ill HLHS kids in the neonatal intensive care unit [NICU] and says that the current method of estimating blood flow rates can lead to severe organ injuries, underdevelopment, underfeeding, and long-term effects on the child, including cognitive deficits. It is an area of great unmet clinical need. Dr. Asija emphasized to us that she really wants to be able to see, over short periods of time, how changes in medication or the feeding plans that she prescribes affect the baby's Qp/Qs ratio.

2. How does your solution work?

Zofia: Our idea modifies existing vascular flow measurement technologies, which take the form of handheld probes. We are looking at ways to turn these technologies into a small implant that is powered and communicated with wirelessly. It would be implanted during the first surgery for HLHS treatment and removed during the second, allowing continuous readings of the all-important Qp/Qs ratio for the critical window between them.

Pedro: After the baby’s first surgery, called the Norwood procedure, a surgically created ‘neo-aorta' allows the right ventricle to pump blood into both the pulmonary and systemic circuits. To allow the communication of blood across these circuits, a GoreTex shunt is placed.

Amin: Our implant would then be removed during the second operation, called the bidirection Glenn procedure, which is when the GoreTex shunt is removed. Our solution wouldn’t involve any extra surgeries, and by avoiding catheterizations, decreases stress on the baby during the intraoperative period. The system would provide continuous, accurate measurements of the Qp/Qs ratio.

3. What motivated you to take on the project? And what activities have you undertaken?

Zofia: We first learned about this need space during our Bioengineering Senior Capstone Design class.

Dylan: We were able to observe some of these babies in the NICU. It's heartbreaking.

Amin: We also saw how much Dr. Asija has to manage when caring for three or four babies at the same time, all with complex pathologies. She does this in collaboration with other NICU physicians, radiologists, nurses, and parents, so we all felt that a better solution could make a huge difference in enabling more informed care decisions and better patient outcomes.

Zofia: This quarter, all of our team members decided to continue this project beyond the BioE Capstone course, and we have focused our efforts on the necessary modifications to existing flow monitoring technologies. We have also learned from several new mentors in the biomedical devices field, and we’re excited that they, along with our Stanford Biodesign mentors, have been very willing to help us. 

Amin: We first focused on demonstrating that the individual components of our solution could work in a neonatal implant. We did some calculations to see how much power the implant would require and if it’s something we could viably supply wirelessly. We also did some proof-of-concept testing of the graft material with different fluids and flow rates to see if we could get signals through without too much loss. Now we’re doing a lot of circuit design and prototyping.

Khanh: The major challenge for our device is making the implant wireless. We’re investigating doing that through inductive coupling, where the power and data between the reader and the implanted device are transmitted via inductive coils. Powering and communicating with our implant wirelessly will help us meet size constraints in the neonatal context, and will allow the implant to take Qp/Qs measurements on-demand.

4. What are the most important things you learned in advancing your project?

Dylan: When we first started the project, it felt daunting to create an implantable device for newborn babies. But what we realized is that some of the individual parts of our solution are already being used in medical and other contexts, so by tapping a network of expert mentors, we’ve been able to pull it all together.

Pedro: We could not have foreseen all the challenges we’ve encountered along the way – for example, how complex circuit design would be under our specific medical constraints, since we don’t come from electrical engineering backgrounds. But we’ve addressed each challenge by seeking out knowledge, as needed.

5. What advice do you have for other aspiring health technology innovators?

Dylan: Don't be afraid to try something. If you had asked us a year ago if we could find a solution to such a technically complicated problem, we probably would have said it isn't possible in such a short timeframe.  But we’ve been able to devise a solution, even if it isn't all the way there yet, which has been very inspiring.

Zofia: Bring your passion into the project and focus on that. It’s surprising and motivating to see how many others are as excited as you are about solving a particular health issue.