Renal sympathetic nerves – what have they got to do with cardiovascular disease?

Abstract

What is the topic of this review? This review examines the role played by renal sympathetic nerves in the regulation of cardiovascular function, focusing on changes that occur during the development of hypertension and heart failure. What advances does it highlight? While elevated levels of renal sympathetic activity are a feature of many cardiovascular diseases, the relationship is not straightforward, especially in the case of hypertension. This review highlights that before consideration of targeting the renal nerves in the clinical management of cardiovascular diseases it is essential that their role in the development of the disease is established. In recent years, with the development of new clinical techniques to target the renal nerves specifically, we have seen a renewed interest in the role of the renal sympathetic nerves in the development of cardiovascular diseases. In understanding the potential of renal nerve ablation for the treatment of cardiovascular disease, first the role played by these nerves in cardiovascular regulation must be determined. Elevated renal sympathetic activity not only has the potential to increase fluid retention but may also act in a feedforward manner to increase sympathetic activation further, increasing the workload of the heart and the potential for arrhythmias. Direct recordings of renal sympathetic nerve activity in animal models of hypertension and renal noradrenaline spillover levels in individual patients with hypertension have illustrated that hypertension is not always accompanied by an increase in renal sympathetic activity. Elevated renal sympathetic nerve activity is a feature of severe heart failure, but whether removal of the renal nerves then compromises the ability to maintain cardiac function when faced with a stressor such as sepsis remains unclear. Understanding when increased renal sympathetic drive is contributing to the progression of cardiovascular diseases such as hypertension and heart failure would appear to be the key to understanding when renal nerve ablation is likely to be of benefit.