During his 29-year career in central Illinois, Dr. Geiss has performed cardiac surgery on over 10,000 patients ranging in age from 92 years to just a few hours old. He grew up in Fargo, North Dakota and entered the seminary at age 14. When he decided the priesthood wasn't his calling, he earned degrees in psychology and classical languages and began postgraduate studies in neurophysiology. "Ultimately I figured out I wasn't meant to study the soul or the brain, but the heart," he says.

He went on to earn his medical degree in Texas during the pioneering cardiac surgery era of Drs. DeBakey and Cooley. After completing his surgical residencies, he sought further training in congenital cardiac surgery. Dr. Geiss began the pediatric cardiac surgery program at the Children's Hospital of Illinois within OSF Saint Francis Medical Center, which now ranks among the top congenital heart programs in the United States.

His practice includes both children and adults. As an extension of his pediatric practice, he has also developed expertise in aortic valve-sparing techniques in adults and in mitral valve repairs, for which he is nationally regarded. "Working with the tiniest and often most complex hearts has made me better at fixing adult hearts, too," he says.

This lead to his interest in robotic cardiac surgery. "It’s a natural extension of minimally invasive pediatric heart surgery." Robotic surgery is much less invasive, avoids a sternal incision, which then facilitates a faster recovery with less discomfort.

Dr. Geiss and his wife have two daughters and four grandchildren. He enjoys biking and flying.