Maduro said early Saturday after meeting with Chavez in Cuba that the ailing president is now "in the best moment we've seen him in these days of struggle" following the surgery.
Maduro spoke on state television after returning from Havana to Venezuela, and before he traveled to Chile for the summit.
"We're taking a message prepared by the president, and we're going to turn it over to heads of state who attend the CELAC summit. He makes fundamental proposals," Maduro said, adding that the message was in Chavez's handwriting.
Maduro said Chavez also sent a message for Venezuelans, including that he was "very optimistic" about his treatment. Maduro said Chavez is "hanging on to Christ and to life."
Chavez has undergone repeated surgeries, chemotherapy and radiation treatment for an unspecified type of pelvic cancer. He has undergone much of his treatment in Cuba.
The 58-year-old president won re-election in October, and lawmakers indefinitely put off his inauguration earlier this month in a decision that was condemned by opponents but upheld by the Supreme Court.
The vice president said that Chavez "has reviewed and evaluated reports on different areas and has made decisions."
He said Chavez evaluated the country's economic situation and budget and made decisions about gold reserves, funding for public housing projects and "social investments and economic development." Maduro didn't give more details but said the actions approved by the president were intended to "guarantee the country's economic growth, infrastructure, housing."
Maduro said that one of the documents signed by Chavez dealt with the selection of his socialist party's candidates for mayoral elections later this year. The vice president showed the signature in red ink on one of the documents.
Associated Press writers Jorge Rueda and Ian James in Caracas, Venezuela, and Chris Gillete in Santiago, Chile contributed to this report.
Luis Andres Henao is on Twitter: https://twitter.com/LuisAndresHenao