Travis, 54, last month completed his court-ordered rehab stemming from a 2012 drunk driving arrest and was touring again when he was struck down by pneumonia, which led to complications of viral cardiomyopathy.
He was airlifted Sunday to an undisclosed Texas hospital where his publicist told People.com Travis Tuesday "underwent placement of an Impella peripheral left ventricular assist device for stabilization prior to transferring hospitals."
"We are very thankful to the fans for their love and support during this time," the representative said.
Sources told TMZ the recording artist's friends and family are privately "frantic" over the deterioration of his health.
Travis' planned concert at South Dakota's Deadwood Mountain Grand Wednesday has been canceled.