Dr. John Ochsner, a surgeon who performed about 12,000 operations, including the first heart transplant in Louisiana, during a career spanning nearly six decades, died Friday morning (July 6) at Ochsner Medical Center of complications of influenza, said his daughter-in-law, Lori Ochsner. He was 91.

The son of Dr. Alton Ochsner, one of the five founders of the medical institution bearing his surname, Dr. Ochsner was a native New Orleanian who earned his medical degree at Tulane University and was a surgical resident at Baylor College of Medicine and Texas Children's Hospital before beginning a New Orleans-based practice that lasted 57 years.

The landmark heart transplant occurred in 1970.

In addition to operating, Dr. Ochsner wrote articles for about 300 medical publications, Ochsner Health System spokeswoman Giselle Hecker said.

In a statement describing Dr. Ochsner as "a consistent, larger-than-life presence," Andy Wisdom, Ochsner Health System board chairman, and Warner Thomas, Ochsner Health System's president and CEO, said, "His sphere of influence spanned across New Orleans, generations of Ochsner physicians and colleagues and the international medical community."

Dr. Ochsner reigned as Rex, king of Carnival, in 1990, following in the royal footsteps of his father, who presided over the 1948 celebration.

Survivors include his wife, Mary Lou Ochsner; two sons, Dr. John L. Ochsner Jr. and Frank Ochsner, both of New Orleans; two daughters, Joby Ochsner of Los Angeles and Dr. Katherine Ochsner of Wilmington, N.C.; a sister, Isabel Ochsner Mann of New Orleans; and two grandchildren.

Funeral arrangements, which are being handled by Lake Lawn Metairie Funeral Home, are incomplete.

Stay with NOLA.com for more on this developing story, including a full obituary.