Dr Krishnan initially did her medical school, residency, and fellowship training in India. Subsequent to that she moved to the United States to complete her pediatrics residency at New York medical college and her Pediatric Cardiology fellowship at Columbia University. She then returned to India to head the Department of Pediatric Cardiology at the Institute of Cardiovascular Diseases and Madras Medical Mission in Chennai India. She set up the first fellowship program, training Indian and international fellows in Pediatric Cardiology in India and getting accreditation for Pediatric Cardiology with the National board of Education in New Delhi. She also co-founded the Pediatric Cardiology Society of India. In 2001 Dr Krishnan moved back to New York to take a faculty position at New York Medical College. She left there is 2010 to take a position at Columbia University in 2010 where she is currently.