3. Results
A total of 21,204 patients received either surgically implanted internal or external BiVADs between 2009 and 2015. The mean age of the population was 51.2 years (standard deviation or SD = 14.4) at the time of implantation (see Table 1). Approximately one quarter (25.1%) of all patients were female, and two thirds (63.7%) were Caucasians. Almost half of the patients (48.4%) had private insurance, and 30.9% had Medicare coverage. Most implantations took place in large (86%), urban teaching hospitals (90.3%), and 18.5% of them occurred as elective admissions.