Tuesday, December 20, 2011

Arrhythmias can be treated by cutting nerves

When the heart beats in an irregular fashion, it can cause all kinds of problems. Our body requires a steady flow of blood, which can be adjusted based on individual requirements of organs and muscles. However, some people have a dysregulated heart beat, called arrhythmia. Our heart beat is ultimately controlled by our brain, which is connected to the heart by nerves. When our natural pacemaker goes haywire, we have a problem. Based on that, researchers from the University of California have developed a method to alleviate the severity of the irregular beats, which is based on cutting some of the nerves that control the heart. This should reduce the high number of deaths associated with arrhythmias.

The therapy is based on cutting four groups of nerves that are set to give impulses to the heart. The required surgery was performed on a total of six patients, to assess whether it would be in any way effective. As it turned out, four out of six patients were completely cured of their arrhythmias, and one of them had only a partial response. Sadly, one of the participants showed no improvement whatsoever. It does however reveal that snipping the nerves can be a very effective treatment.

The nervous system
Surgeons snip the nerves that belong to a specific part of the nervous system: the sympathicus. This part is involved with regulating autonomous functions of our bodies, predominantly in what is described as the 'fight or flight' response. The sympathic nervous system sends signals that readies our body to perform physical activity and halts the blood flow to the intestines, which need not to be very active at that point. The parasympathic part of the nervous system works in exactly the opposite way, and is sometimes referred to as 'rest and digest'.

Heart beats
The sympathic nervous system increases the speed at which our heart beats, as we need a high supply of blood to our muscles during the fight or flight response. We already know this from experience: in a stressful situation, your heart beat rises. This is also influenced by adrenalin. However, if the impulses coming from the sympathicus are not properly regulated, our heart can suddenly start beating much faster. In what scientists call an 'electrical storm' the heart can be overloaded with impulses, which leads to damage, and in 400.000 cases each year in the US, to death.

Normally, arrhythmias can be countered by inducing a proper rhythm with an artificial pacemaker, but this does not help in severe, and lethal, cases. Albeit a quite drastic surgery, snipping the sympathic nerves seems to be effective in preventing deadly arrhythmias. However, the scientists will need a larger clinical trial to confirm their findings, which are likely to be underway already.
The ECG of an arrhythmic patient. Distance between the peaks varies, indicating irregular heart beats.

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