Renal Artery Denervation in Chronic Heart Failure

Overview

Heart failure is a common condition with debilitating symptoms and a poor prognosis. Patients with heart failure have a massively overactive sympathetic nervous system which attempts to compensate for their poorly functioning heart. This ultimately has only detrimental effects. One of the principle mediators for this sympathetic response is found in the nerve cells in the kidneys. Whilst a significant proportion of medications used to treat heart failure act on these harmful pathways, none target the kidney sympathetic-nerve cells specifically. Additionally, because of their multiple sites of action these drugs all have side effects. A new procedure that has recently been developed for the treatment of high blood pressure is renal denervation. This involves inserting a small catheter through the femoral artery and passing it to the kidney artery under x-ray guidance. From there, using radiofrequency waves, the sympathetic nerves within the kidney can be destroyed. The investigators anticipate that this procedure will have a significant positive effect on patients with heart failure and aim to perform a pilot safety study on 7 individuals with advanced heart failure to assess its safety and effectiveness. The investigators hypothesise that renal artery denervation will lead to significant clinical and biochemical improvements in patients with marked heart failure.

One of the key physiological changes seen in heart failure patients is overactivity of the sympathetic nervous system. This is a homeostatic response produced by the body in an attempt to compensate for a poorly functioning heart and the resultant underperfused tissues. In acute heart failure this has a positive effect but in chronic heart failure, the long standing sympathetic overactivity causes multiple undesirable side effects including profound vasoconstriction, increased sodium reabsorption by the kidneys, renin release and decreased renal blood flow. Afferent and efferent sympathetic chains in the renal artery play an important role in the mediation of this response. Current management of heart failure principally hinges on drugs that attempt to attenuate or interrupt this response via renin angiotensin system, adrenoreceptors or the renal tubules. These drugs have multiple side effects, partly because of their multiple sites of action. None directly target the sympathetic discharge at its source. The development of renal artery denervation opens a unique opportunity for potentially longlasting relief of this intense renal sympathetic over-activity. The technique has a current role in the management of resistant hypertension where it has shown very favourable results with minimal side effects. The investigators envisage that this technique could also be highly beneficial to patients with heart failure by directly interrupting this sympathetic overactivity. This initial study involving 7 patients is a pilot safety study to assess this potential.