Following months of planning by the Canadian Blood Services, four people with severe kidney failure received new kidneys from living donors in simultaneous operations in three cities Wednesday.

The four-way, multi-city kidney swap was a Canadian first, and involved surgeries in three hospitals in three cities in three time zones: Toronto, Edmonton and Vancouver.

Three of the four patients had relatives willing to offer a kidney but who weren't good matches because of incompatible blood group or tissue type. The fourth patient was on a waiting list to receive a kidney from a deceased person.

The "domino effect" was set off after an altruistic donor from B.C. who offered to give one of his or her two healthy kidneys to a stranger (The names and genders of the donors and recipients have not been revealed).

That recipient then had his or her donor partner give a kidney to another patient in the registry. That recipient's donor partner gave a kidney to a third person in the registry, whose partner then gave to a patient on the waiting list without a partner.

This logistically complex "domino" transplant began at 10:30 a.m. (ET) in three time zones. The kidneys were removed from the donors and the four transplant operations went ahead in sequence with the help of two dozen doctors and nurses.

By Wednesday evening, all four donors and recipients were recovering, with two pairs in Toronto recovering in the same hospital on different wards to safeguard their anonymity.

The transplants were coordinated to all occur on the same day to lessen the possibility that any of the donors would change their minds once their own partners had recieved their new organs.

Ed Cole, head of the University Health Network's kidney transplant program in Toronto, said the swap was a great success, noting that the people who got kidneys would have waited on transplant lists for years.

"It shows what can be done when we work together," he told the Globe and Mail.

Both the Toronto General Hospital and the Ottawa Hospital have done their own rounds of "kidney swap" surgeries, but Wednesday surgeries were the first national domino exchange.

The domino transplant was made possible thanks to the CBS's new national kidney registry, called the Living Donor Paired Exchange Registry. It allows donors who can't give a kidney to their loved one because of a mismatch to sign up in pairs to swap kidneys with another incompatible donor-recipient pair. It also allows for those who want to donate their kidney anonymously to anyone who needs it.

When CBS announced the program in February, it forecast that the registry would increase live kidney donations in Canada by 20 per cent or more. Already, the registry has about three dozen incompatible donor-recipient pairs looking to "swap" kidneys.

The CBS is expanding the registry and is already planning a second domino transplant this summer.

About 35,000 Canadians suffer from kidney disease and 3,000 of them are on waiting lists for a transplant, according to the Canadian Organ Replacement Register (CORR).

In 2007, there were nearly 1,200 kidney transplants performed in Canada, with about 480 coming from live donors.

While kidney transplants carry some medical risk, the benefits to kidney disease patients are enormous. Many are able to end dialysis treatments and return to normal lives.

Studies have also shown that kidney transplants conducted through paired donations save the healthcare system an average of $1 million per transplant compared to the costs of keeping that patient on long-term kidney dialysis.