Research that's been going on in the area of heart failure in a very broad sense has taken on two dimensions. One has been our classic way of understanding heart failure -- and that's been the study of the heart, the physiology of it -- and then trying to design drugs to interact with that physiology to make patients better.
We've been very successful at that and have reduced the morbidity and mortality associated with heart failure as a result of those treatments. However, we haven't had very many new drugs make a major impact in the last several years.
What has made a major impact is the use of devices to treat heart failure. Two in particular have attained broad use and those are the use of implantable cardioverter defibrillators for patients who have low ejection fraction. This is a pacemaker-like device that can provide an electrical shock if somebody's heart should stop to get it started again. And those devices are very efficient at doing that.
It turns out that people who have low ejection fraction are at particularly high risk of having a cardiac arrest. And before they ever have a rhythm disturbance, we can actually give them one of these and improve their chances of living longer. There are pros and cons and this has to be discussed in detail with the patient's doctor. But certainly this is a life-saving therapy that's been developed in the last several years, and now is broadly applied in patients with heart failure.
Also is the use of pacing therapies. I mentioned before when the electrical system of the heart is diseased as many times it is in about a quarter to a third of patients with heart failure, we can overcome those inefficiencies associated with the diseased electrical system by special pacing means. Biventricular pacing or cardiac-resynchronization therapy has been a means that we can improve those. We've been very busy at Hershey in clinical trials regarding those two therapies.
We also have a long history of study in the area of neurocirculatory control -- how the nervous system interacts with the circulation in order to control blood flow and blood pressure. We've studied that in heart failure a great deal and have attained a great deal of knowledge in that area.
One of the areas we're probably best at Hershey as well is in the area of mechanical circulatory support. Hershey was the inventor of the Thoratec left ventricular assist device and another total artificial heart that now is owned by AbioCor was developed there, the Penn State Heart. Those two devices have been very effective in the animal studies and the Thoratec left ventricular assist device has been used for many years throughout the world -- that's the first long term device that was available for use in patients whose circulation had failed.
Now what we're trying to understand is how these hearts recover when they're on mechanical support. We're involved in two projects. One is to look how the hearts recover when the work of the heart is taken away by a mechanical blood pump. And the second is try to understand what gets better when we relieve the stress of the heart and what areas we still need to improve.
Hopefully, we can provide an opportunity for the heart to rest and heal, and then remove the pump. Typically what we do now is either leave the pump in place indefinitely and that's the patient's therapy or we get the patient to a heart transplant where the new heart becomes their ultimate therapy.
Our hope is that we can give the heart a rest when it becomes to an area where it's failing and all our usual therapies are not working, be able to apply a treatment in that interim, and then be able to recover the heart, and hopefully the person will do well for a long period of time.