A miniaturized heart pump was able to help keep eight out of nine critically ill children alive long enough until a donated organ was available, researchers announced on Monday.

The heart assist devices advertized in the United States are available for almost all adults, but too large for lots of children. The U.S. will have to wait longer until devices adjusted for a child's smaller anatomy will be approved for sale. In other parts of the world, such as the European continent, these types of devices have already been approved. According to study author Dr. Sanjiv Gandhi of the Saint Louis Children's Hospital in Missouri, the main reason they haven't been approved yet in the U.S. is that the market is quite small, and additional clinical trials have to be carried out.

"Up until now there were no available pumps for children who are in end stage heart failure and in need of some sort of bridge while waiting for a suitable donor organ to come along," Ghandi said during a telephone interview.

The team of U.S. researchers tested Excor pediatric ventricular assist device, a mechanical cardiac support system made by Berlin Heart GmbH which is used in severely ill people with heart failure. In the trial, nine children aged 12 days - 17 years received the device under a special program for patients who don’t have an alternative, Bloomberg reported. Whereas devices from World Heart Corp., Thoratec Corp, HeartWare Ltd. and Ventracor Ltd. are accessible or under development both for adults and older children, younger American children have few choices as regards treatment.

All children (seven girls and two boys) were suffering from severe heart failure and were very thin, weighting less than 40 kilograms – or 88 pounds. They were in this critical condition either as a consequence of serious birth defects of the muscular organ, either because of cardiomyopathy, which occurs when the heart muscle becomes inflamed and doesn't work as well as it should.

After the heart assist devices were given to the young patients and while waiting for a heart transplant, one child passed away from kidney failure that aggravated subsequent to the surgery performed to install Excor. The others managed to stay alive and, following the 77 days of follow-up, each one received the needed organ transplant.

Although many people are in need of an immediate heart transplant, they often confront with a major problem: the waiting list. According to the Organ Procurement and Transplantation Network (OPTN), more than 250 children under the age of 17 are waiting to undergo surgery for the transplant.

The price of Excor pediatric ventricular assist device is an estimated $50,000. Berlin Heart, which is the only company worldwide that offers such devices for all patients, no matter their age and body size, initiated a study last December that may lead to Food and Drug Administration approving the device for use in the United States.