The Ravenclaw

The Pediatric BiVAD

Group Members:

Sylvana Guirguis, Jinesh Patel, Wee Wen Leow, Laura Hernandez-Cruz, Jake Mitchell, Allen Jarzombek, and Darren Drake

For this project, our problem was to design a totally implantable pediatric heart that serves as either a bridge to recovery, bridge to transplant, or a permanent device. Although one in five people suffer left-side ventricular failure, only a minority are candidates for VADs. To be considered for a VAD, patients must meet specific criteria with regard to blood flow, blood pressure, and general health. VADs are actually available to all patients in cardiovascular crisis, but their uses is not recommended for patients with certain diseases such as severe liver disease, advanced age, infections, irreversible renal failure, etc. Some of the difficulties we faced when working on this device was the patient size, anticoagulation, and growth.

The Ravenclaw BiVAD Device

The device features a magnetically levitated impeller that minimizes blood-related complications such as thrombus formation and hemolysis. There are two such impellers stacked on top of each other inside a titanium casing. The blood flow is continuous. Other components of the device include a flow-straightener and a diffuser. We are using titanium inlet cannulae to connect the pump to the ventricular apexes of the heard and Dacron weave tubes to connect the pump to the aorta and pulmonary artery. Our tubing is going to have a textured surface to promote neointima formation which will reduce the risk of thromboembolic complications. The entire device and pump will be monitored and controlled by a microship inserted in the pump. Our device will be powered by an internal power supply as well as an internal power supply, so that no cords or wires will be coming out of the patient’s body, thus reducing risk of infection.

There are several aspects we will need to monitor with this device, and we do this by using probes that are inserted to collect such important data as blood velocity, frequency of flow, and volume of flow. We will also be using Doppler ultrasound as a monitoring system for our design.

As an added innovation to the traditional BiVAD, we will also be using Angiotensin II as another monitoring device. We will use sensors to detect receptor gene expression in the cardiomyocytes. This will then send feedback to the device. The more gene expression that is seen, then the older child is getting, and thus we will lower the heart rate to match the weight-to-biding site ratio. Another innovative component is our rate-adaptive pacing system which uses “activity sensing” to achieve rate modulation at a speed proportional to the lever of exercise load.

The Ravenclaw is indicated for use to provide temporary left side mechanical circulatory support as a bridge to cardiac transplantation for pediatric patients in these ranges:

• 7-16 years of age
• With Body Surface Area > 1.0 m2 and <1.5>
• Who are in NYHA Class IV end-stage heart failure
• Who are refractory to medical therapy and who are (listed) candidates for cardiac transplantation.

Some considerations of using the device include but are not limited to use of anti-coagulants to prevent thrombosis and to allow for recirculation underneath the imepllers, preventative antibiotics to combat infection, possible shearing of red blood cells, patients cannot engage in excessive exercise, and cannot be exposed to MRIs.