All you need to know about a 'heart assist device'

Chennai: Tamil Nadu Chief Minister J Jayalalithaa suffered cardiac arrest on Sunday, just days after doctors said she was well and could leave Apollo Hospital whenever she wanted to.

Following the development, the CM was put on an extracorporeal membrane oxygenation (ECMO) device, commonly called a heart-assist device.

Read: Tamil Nadu CM Jayalalithaa very critical, on life support: Apollo Hospitals

So what exactly is an ECMO or heart-assist device?

An extracorporeal medical procedure is one which is performed outside the body. ECMO is a technique of providing both cardiac and respiratory support to persons whose heart and lungs are unable to provide an adequate amount of gas exchange to sustain life.

ECMO works by removing blood from the person's body and artificially removing the carbon dioxide and oxygenating red blood cells.

The blood is pumped directly into the body to energise it as the heart and lungs are unable to perform the pumping function.

The procedure was earlier performed mostly on children but is now being increasingly used on adults too.

Criteria for the initiation of ECMO include acute severe cardiac or pulmonary failure that is potentially reversible and unresponsive to conventional management, according to the Extracorporeal Life Support Organisation.

The use of ECMO has been shown to improve survival rates, say some scientific  papers.

A 2009 scientific paper by US-based doctors Thomas V Brogan, Ravi R Thiagarajan, Peter T Rycus, Robert H Bartlett and Susan L Bratton said that survival rates of 50 to 70  per cent have been recorded in uncontrolled clinical trials.