BIOMED PhD Research Proposal
Title:
Development of a Geometrically Tunable Cardiovascular Shunt for Pediatric Heart Reconstruction
Speaker:
Akari Seiner, PhD Candidate
School of Biomedical Engineering, Science and Health Systems
Drexel University
Advisor:
Christopher Rodell, PhD
Assistant Professor
School of Biomedical Engineering, Science and Health Systems
Drexel University
Details:
Congenital heart defects (CHDs) are among the top eight causes of infant mortality worldwide. Annually, CHDs affect around 40,000 infants in the United States, with approximately one in four having a critical CHD that requires surgical intervention within the first year of life. A subset of critical CHDs, such as hypoplastic left heart syndrome (HLHS), are characterized by single ventricle (SV) anatomy, wherein hypoplasia of the left ventricle and aorta leads to the right ventricle needing to support both pulmonary and systemic circulation. Without surgical intervention, SV defects are universally fatal. The current standard of care is a palliative three stage open heart reconstruction procedure, referred to as the Norwood–Glenn–Fontan procedure.
The first stage typically involves the creation of a neo-aorta and installation of a fixed-diameter modified Blalock–Taussig (mBT) shunt composed of expanded polytetrafluorethylene (ePTFE) tubing to connect the innominate or subclavian artery to the pulmonary artery. This connection of pulmonary and systemic circulation is crucial, as it allows for sufficient blood supply to the body and lungs by a single ventricle. However, maintaining a proper balance of pulmonary to systemic blood flow is difficult to achieve, as it is dependent on the careful selection of shunt diameter—too narrow of a shunt may lead to high internal resistance, high shear stress, and hypoperfusion, whereas too wide of a shunt may lead to pulmonary over-circulation and heart overload. While procedural modifications have improved patient prognosis, mortality rates remain among the highest in cardiothoracic surgery and have failed to improved substantially since the procedure was developed over thirty years ago. A primary limitation is the shunt’s inability to accommodate the physiological changes associated with the infant growth during 3–6 months after shunt implantation (the Norwood stage). As a result, 28% of patients experience major adverse events, and nearly half (47.9%) require at least a second open thoracotomy to revise the shunt diameter, increasing the risk of peri- and post-operative complications and mortality.
There is a dire need for innovative solutions that enable these blood shunts to change in diameter without major surgery. Such a geometrically tunable blood shunt would provide clinicians with the unique ability to precisely balance pulmonary and systemic blood flow in direct proportion to infant growth. Towards that, we aim to develop a photoresponsive hydrogel lined conduit, wherein the outer surface of the shunt would provide the mechanical strength required for blood pressure resistance and a biocompatible polymer based hydrogel coated on the inside of the shunt would provide on demand inner lumen diameter increases upon exposure to minimally invasive light-emitting catheter. The ability to regulate the inner lumen diameter of the shunt could allow for more precise hemodynamic control, improving patient outcomes and reducing the risk of life-threatening complications. The unique approach holds promise to pave the way for other dynamic medical devices, such as vascular grafts or other implants, that can be temporally controlled for personalized medicine.