The feasibility, efficacy, and safety of RDN procedure using CO2 angiography through radial artery in severe chronic kidney disease patients

Renal denervation: a key approach to hypertension and cardiovascular disease

Sympathetic activation plays a critical role in the development of hypertension and cardiovascular disease, including heart failure and arrhythmias. Renal nerves contribute to the regulation of blood pressure and fluid volume through renal sympathetic efferent nerves, and to the modulation of sympathetic outflow through renal sensory afferent nerves. Previous studies including ours suggest that selective afferent renal denervation with preservation of efferent renal nerves can significantly decrease central sympathetic outflow in animal models of hypertension with renal damage. In Dahl salt-sensitive rats fed high salt diet from an early age, a model of hypertensive heart failure, this central sympathoinhibition by afferent renal denervation may attenuate the development of heart failure without significant blood pressure reduction. Accumulating clinical evidence supports the efficacy of renal denervation as an antihypertensive treatment. However, it remains important to clarify the appropriate indications and predictors of responders to renal denervation in the treatment of hypertension. Several clinical studies suggest beneficial effects of renal denervation in patients with heart disease, with or without hypertension, although most were not sham-controlled. In particular, some clinical studies have demonstrated that renal denervation reduces the incidence of atrial fibrillation or cardiovascular events even without a significant antihypertensive effect. It is essential to accumulate more insightful data in patients undergoing renal denervation, to establish the efficacy of renal denervation in patients with cardiovascular disease in the clinical setting, and to elucidate the therapeutic mechanisms of renal denervation and the renal nerves-linked pathophysiology of cardiovascular disease in basic research. This review outlines the effects of renal denervation on sympathetic activity and organ damage in animal models of hypertension and hypertensive heart failure, including our own data. Beyond the antihypertensive effects, the beneficial effects of renal denervation on cardiovascular disease are also discussed based on clinical studies. Several animal and clinical studies suggest the cardioprotective effects of renal denervation even in the absence of significant blood pressure reduction, probably due to its sympathoinhibitory effects.

Aspects of renal function and renal artery anatomy as indications for renal denervation

Renal denervation (RDN) is a minimally invasive, endovascular catheter-based procedure using radiofrequency, ultrasound, or alcohol-mediated ablation to treat resistant hypertension. As more attention is focused on the renal sympathetic nerve as a cause and treatment target of hypertension, understanding the anatomy of the renal artery may have important implications for determining endovascular treatment strategies as well as for future selection of devices and appropriate candidates for RDN treatment. However, the anatomical structure of the renal artery (RA) is complex, and standardized morphological evaluations of the RA structure are lacking. Computed tomography angiography or magnetic resonance angiography imaging is useful for assessing RA anatomy before conducting RDN. RA echocardiography is an established noninvasive screening method for significant stenosis. Major randomized controlled trials have limited enrollment to patients with preserved renal function, usually defined as an estimated glomerular filtration rate (eGFR) ≥ 45 mL/min/1.73 m2. Therefore, the level of renal function at which RDN is indicated has not yet been determined. This mini-review summarizes the characteristics of renal artery anatomy and renal function that constitute indications for renal denervation. (Role of Clinical Trials: K. Kario is an Executive Committee Principal Investigator for the Spyral OFF MED, the Spyral ON MED, the DUO and the REQUIRE; a Coordinating investigator for the TCD-16164 study; a Site Principal Investigator for the HTN-J, the Spyral OFF MED, the Spyral ON MED, the DUO, the REQUIRE and the TCD-16164 study). Evaluation of renal arteries for radiofrequency renal denervation. A Simultaneous quadrantal ablations at four sites in the main renal artery or the equivalent renal artery to the main renal artery. B If there is a renal artery branch with a diameter >3 mm in the middle of the main renal artery, this branch is the distal end of the main renal artery. In this case, four simultaneous and quadrantal ablations can be performed on the equivalent renal arteries. C Four simultaneous and quadrantal ablations can be performed in the branch renal artery. D Sonication should be spaced at least 5 mm (one transducer*) apart. Perform 2 to 3 mm proximal to the arterial bifurcation. Perform 2 to 3 mm distal to the abdominal aortic inlet.