Dr. Callahan was born in State College, Pennsylvania and remained local as an undergraduate at Penn State University. He subsequently attended Drexel University College of Medicine for his medical degree and completed his pediatric residency and pediatric cardiology fellowship training at the Children’s Hospital of Pittsburgh. Dr. Callahan then came to Boston Children’s Hospital where he completed a senior fellowship in interventional pediatric cardiology. As staff in the invasive cardiology division, his primary interest includes transcatheter management of congenital heart disease, with a focus on pulmonary vein stenosis and the treatment of right ventricular outflow tract dysfunction. Further, he is interested in simulation and applying it to the training of cardiology fellows in the catheterization laboratory.