Southland rugby player Hoani Macdonald has undergone heart surgery as he continues to recover from a cardiac arrest during Saturday's championship semifinal at Pukekohe.

Stags manager Glenn Morrison said tests to date on Macdonald's heart had been encouraging and had identifed no long term damage.

As a safeguard Macdonald underwent a procedure this morning where an implantable cardioverter-defibrillator (ICD) was implanted in his chest.

"He has made real improvements in the last few days and is looking forward to being able to move onto the next stage of his recovery with his family,'' Morrison said.

An ICD  is a small battery-powered electrical impulse generator that is implanted in the chest of at risk patients programmed to detect and correct cardiac arrhythmia.

Stags captain Jamie Mackintosh said Macdonald's team mates had been deeply affected by the incident.

''The lads were really worried there for a while, when its one of your mates, especially someone who has been around the team for as long as Hoon. it's hard to comprehend something like this happening. We were all a bit in shock really.''

The Stags called off their annual end of season bus trip on Sunday and instead stayed in Invercargill as a team while they waited for news from Middlemore Hospital.

The team and Rugby Southland staff have signed a Stag-themed get well card for Macdonald which will be delivered this weekend.

''We are all behind him in his recovery 100 per cent, he is a special guy to Southland rugby and, while it was touch and go there for a while, he is a tough bugger and it's showing through in how he is bouncing back,'' Mackintosh said.

Rugby Southland has a book available at reception for those wishing to send a short personal message to Macdonald and his family.

- © Fairfax NZ News