Dr. Tierney graduated from the combined Siena College/Albany Medical College Program of Science, Humanities and Medicine in Albany, New York where he was one of the first students in the country to take part in a premedical program with emphasis on the humanities. It was one of the first medical education programs with a distinct focus on service to others. As part of the program, he completed medical missions at orphanages in Mexico and at the Infant Welfare Society in downtown Chicago. 

After medical school, Dr. Tierney completed a combined residency in Internal Medicine and Pediatrics at Loyola University Medical Center. He then completed fellowships in Adult Cardiology and Clinical Electrophysiology, also at Loyola. He is currently Board Certified in Cardiology and Clinical Cardiac Electrophysiology. He has previously served as Assistant Professor at Loyola University Medical Center prior to joining Heart Care Centers of Illinois in 2004. He currently is Director of The Electrophysiology Lab at MetroSouth Medical Center (formerly known as St. Francis) in Blue Island since 2005. 

Dr. Tierney performs implantation of pacemakers, defibrillators and biventricular devices used to improve congestive heart failure. He also performs catheter ablations to help cure fast heart rhythm conditions. His research interests include applications of biventricular device therapy and prevention of sudden death along with the diagnosis and treatment of syncope or passing out.