I'm guessing she wants to know how those attributes are "acquired". How does one acquire focus and deep expertise in Cardiology billing?
Practice. Practice. Practice.
Work in a Cardiologists office to learn the language and the procedures.
Do Cardiology billing, but with access to an experienced Cardiologist biller who can answer your questions.
Billing for any specialty (Cardiology; Gastroenterology; OB/Gyn; etc.) is a much different animal than simply billing for office visits in a General Practitioner's office.