Heart failure can be caused by a narrowing of the small blood vessels that supply blood and oxygen to the heart. Another cause is high blood pressure that is not well controlled. This can lead to stiffness and muscle weakening. Coronary artery disease can also be a cause. When plaque builds up in the arteries, less blood can reach the heart, causing it to work harder. Heart attacks can essentially kill parts of the heart muscle which were starved of oxygen, making the heart work more to compensate for the lost muscle. Even lung disease can be a cause: if the lungâ??s ability to provide enough oxygen to the body is impaired, the heart has to compensate by pumping more blood.The CardioFit nerve stimulator acts almost like an implantable pacemaker. Itâ??s placed under the skin of the chest and consists of a stimulator, a sensor lead, and a stimulation lead. The sensor lead monitors changes in the heart and a stimulation lead is attached to the vagus nerve, which can trigger the parasympathetic nervous system when stimulated. The parasympathetic nervous system has been shown to be able to reduce heart rate, which in turn reduces the workload on the heart. Current to the nerve is increased based on the response of the heart rate. The CardioFit can be programmed on and off with external wireless communication. It can take about 6 to 12 weeks to respond to the treatment. Vagus nerve stimulation has also been proven to be effective in treating epilepsy and depression. Thereâ??s one vagus nerve on each side of the body, which runs from the brainstem through the neck then to the chest and abdomen.