The National Party says the health service will have difficulty increasing the rate of cardiac surgery because of a shortage of specialist nurses.

Health Minister David Cunliffe announced today $50 million over four years would be reallocated from other areas so that more heart operations could be carried out.

His announcement coincided with the release of a report which said New Zealand was lagging behind other developed countries in heart surgery rates and patients were waiting longer than they should.

It also found that there was "little correlation" between how acutely a person needed surgery and when they got it.

Mr Cunliffe commissioned a working group of cardiac surgeons and others in the field to prepare the Cardiac Surgery Services in New Zealand report.

It said New Zealand suffered a relatively high level of heart disease but the surgery rate was lower than in comparable countries.

National's health spokesman, Tony Ryall, said the Government was warned about the falling rate of cardiac surgery in a 2003 ministry report.

"Right now, patients' lives are at risk from these failing cardiac services," he said.

"The expansion of cardiac surgery will be important, but difficult with the shortage of cardiac intensive care unit nurses, particularly in Auckland."

Mr Ryall said there was a general shortage of nursing and theatre staff in other surgical areas as well.

"After nine years and 55 reports on the health workforce crisis, Labour is still missing in action on that issue," he said.

The report said it was concerning is that waiting times for publicly funded cardiac surgery have been reduced to clinically acceptable levels in many other countries, but not in New Zealand.

It said there were "significant" variations depending which part of the country a patient lived in.

The number of cardiac surgical operations declined between 2002-03 and 2006-07.

The level of service patients got in Australia was 85 percent higher than in New Zealand. Canada was 75 percent higher and the United Kingdom was 37 percent higher.

The working group said cardiac surgery rates should be increased from 54 per 100,000 people to 73 over the next five years -- a 35 percent increase.

The report said funding was not the only factor limiting improvements and the biggest challenge was capacity of District Health Boards to deliver.

Recruitment and retention of key staff was vital.

In response, Mr Cunliffe said the Government had set higher targets than those recommended in the report.

"Moving towards nationally consistent prioritisation of patients across the five cardiac centres will ensure those with greatest need and ability to benefit get fairer access to services regardless of where they live," he said.

"The nature of this complex service means we are working closely with the sector to improve the service in a sustainable manner that will reduce surgery cancellation."

Mr Cunliffe said all recommendations would be implemented.