The deaths of up to 250 patients who died following heart surgery at St George's Hospital are to be reviewed.

All the patients underwent surgery at the Tooting site between April 2013 and September 2018.

The review, commissioned by NHS Improvement, comes after the hospital suspended complex heart surgery last year to improve services.

A leaked report suggested that poor relationships between surgeons at the cardiac unit contributed to a higher mortality rate.

The panel will also review deaths between April 2017 and September 1 2018, a period during which improvements were being introduced by the trust.

The trust said families of cardiac surgery patients who died during the review period will be contacted if the panel identifies "any significant concerns about their care".

Jacqueline Totterdell, chief executive at St George's, said: "It is absolutely essential that patients and their families have full confidence in the care our cardiac surgery team provide - and this review of past deaths will be a key part of that process."

During the review, the medical records of those who died will be examined, alongside any investigations conducted by the trust at the time of the patients' deaths.

The leaked report last year said a "toxic" feud between two rival camps at the heart surgery unit left staff feeling a high death rate was inevitable.

St George's Hospital heart unit was said to be consumed by a "dark force" and patients were put at risk by a dysfunctional team of surgeons.

At the time, it said the hospital had a cardiac surgery death rate of 3.7% - above the national 2% average.

Conversations with 39 staff revealed they were shocked by the death rate, but "most felt that poor performance was inevitable due to the pervading atmosphere".

In December, Care Quality Commission inspectors reported they had found top physicians with "strong" personalities unable to work together effectively.

According to their subsequent report, "consultant surgeons mistrusted each other, as well as cardiologists, anaesthetists and senior leaders."

There was also culture of "tribalism", one consultant said.