SYDNEY (AFP) - Australian Olympic swimming champion Kyle Chalmers Tuesday said he had undergone successful surgery to treat a worsening heart condition.

The Rio 100m freestyle gold medallist announced last month that he was pulling out of July's world championships in Budapest to get the problem fixed.

"Double thumbs up because this time my heart surgery was successful! Thank you all for the support," he said on his Instagram page.

A previous operation had not helped the 18-year-old's supraventricular tachycardia, which occasionally causes his heart to race.

The condition forced him to miss Australia's national short course championships late last year, with his doctor and coach deciding he needed surgery to help prolong his career.

Ahead of the surgery, Chalmers said he had suffered symptoms during two of his last three major meets and was following doctor's orders to undergo the procedure.

"The symptoms have reached a point where I must act to ensure I am in peak physical condition for next year's Commonwealth Games trials and hopefully the Commonwealth Games," he said, of the event which will be held in Australia's Gold Coast.