Nevada state officials have begun an investigation to determine if payments to cardiologists there by a little-known heart device company were legitimate consulting fees or inducements to the doctors for using its products. Gov. Brian Sandoval on Monday asked state health officials to look into whether the dealings between the doctors and a company called Biotronik had involved improper billing practices or patient safety issues, according to a spokeswoman, Mary-Sarah Kinner. The inquiry follows a report on Sunday in The New York Times that heart device specialists at a Las Vegas practice started using Biotronik implants in nearly all their patients in 2008 after company documents showed they became consultants to the device maker, getting up to $5,000 a month in fees.