Renal Sympathetic Denervation Improves Outcomes in a Canine Myocardial Infarction Model

Effects of renal denervation on the incidence and severity of cardiovascular diseases

Renal denervation (RDN) is a neuromodulation therapy performed in patients with hypertension using an intraarterial catheter. Recent randomized sham-controlled trials have shown that RDN has significant antihypertensive effects that last for more than 3 years. Based on this evidence, the US Food and Drug Administration has approved two devices, the ultrasound-based ReCor ParadiseTM RDN system and the radiofrequency-based Medtronic Symplicity SpyralTM RDN system, as adjunctive therapy for patients with refractory and uncontrolled hypertension. On the other hand, there have been no randomized sham-controlled prospective outcome trials on RDN, and the effects of RDN on cardiovascular events such as myocardial infarction, heart failure, and stroke have not been elucidated. This mini-review summarizes the latest findings focusing on the effects of RDN on organ protection and physiological function and symptoms in both preclinical and clinical studies. Furthermore, the feasibility of using blood pressure as surrogate marker for cardiovascular outcomes is discussed in the context of relevant clinical studies on RDN. A comprehensive understanding of the beneficial effects of RDN on the incidence and severity of cardiovascular diseases with their underlying mechanisms will enhance physicians' ability to incorporate RDN into clinical strategies to prevent cardiovascular events including myocardial infarction, heart failure, and stroke. This mini-review focuses on the effects of RDN on organ protection and physiological function and symptoms in preclinical and clinical studies. RDN is expected to reduce the onset and progression of cardiovascular diseases including myocardial infarction, heart failure, and stroke in clinical practice. LV left ventricular, LVEF left ventricular ejection fraction, VO2max maximal oxygen uptake, VT ventricular tachycardia, VF ventricular fibrillation, 6MWD 6-min walk distance, NT-proBNP N-terminal pro-B-type natriuretic peptide, NYHA New York Heart Association, BBB blood-brain barrier, BP blood pressure.

Animal models and animal-free innovations for cardiovascular research: current status and routes to be explored. Consensus document of the ESC Working Group on Myocardial Function and the ESC Working Group on Cellular Biology of the Heart

Cardiovascular diseases represent a major cause of morbidity and mortality, necessitating research to improve diagnostics, and to discover and test novel preventive and curative therapies, all of which warrant experimental models that recapitulate human disease. The translation of basic science results to clinical practice is a challenging task, in particular for complex conditions such as cardiovascular diseases, which often result from multiple risk factors and comorbidities. This difficulty might lead some individuals to question the value of animal research, citing the translational 'valley of death', which largely reflects the fact that studies in rodents are difficult to translate to humans. This is also influenced by the fact that new, human-derived in vitro models can recapitulate aspects of disease processes. However, it would be a mistake to think that animal models do not represent a vital step in the translational pathway as they do provide important pathophysiological insights into disease mechanisms particularly on an organ and systemic level. While stem cell-derived human models have the potential to become key in testing toxicity and effectiveness of new drugs, we need to be realistic, and carefully validate all new human-like disease models. In this position paper, we highlight recent advances in trying to reduce the number of animals for cardiovascular research ranging from stem cell-derived models to in situ modelling of heart properties, bioinformatic models based on large datasets, and state-of-the-art animal models, which show clinically relevant characteristics observed in patients with a cardiovascular disease. We aim to provide a guide to help researchers in their experimental design to translate bench findings to clinical routine taking the replacement, reduction, and refinement (3R) as a guiding concept.

Renal Sympathetic Denervation Attenuates Congestive Heart Failure in Angiotensin II-Dependent Hypertension: Studies with Ren-2 Transgenic Hypertensive Rats with Aortocaval Fistula

OBJECTIVE

We examined if renal denervation (RDN) attenuates the progression of aortocaval fistula (ACF)-induced heart failure or improves renal hemodynamics in Ren-2 transgenic rats (TGR), a model of angiotensin II (ANG II)-dependent hypertension.

METHODS

Bilateral RDN was performed 1 week after creation of ACF. The animals studied were ACF TGR and sham-operated controls, and both groups were subjected to RDN or sham denervation. In separate groups, renal artery blood flow (RBF) responses were determined to intrarenal ANG II (2 and 8 ng), norepinephrine (NE) (20 and 40 ng) and acetylcholine (Ach) (10 and 40 ng) 3 weeks after ACF creation.

RESULTS

In nondenervated ACF TGR, the final survival rate was 10 versus 50% in RDN rats. RBF was significantly lower in ACF TGR than in sham-operated TGR (6.2 ± 0.3 vs. 9.7 ± 0.5 mL min-1 g-1, p < 0.05), the levels unaffected by RDN. Both doses of ANG II decreased RBF more in ACF TGR than in sham-operated TGR (-19 ± 3 vs. -9 ± 2% and -47 ± 3 vs. -22 ± 2%, p < 0.05 in both cases). RDN did not alter RBF responses to the lower dose, but increased it to the higher dose of ANG II in sham-operated as well as in ACF TGR. NE comparably decreased RBF in ACF TGR and sham-operated TGR, and RDN increased RBF responsiveness. Intrarenal Ach increased RBF significantly more in ACF TGR than in sham-operated TGR (29 ± 3 vs. 17 ± 3%, p < 0.05), the changes unaffected by RDN. ACF creation induced marked bilateral cardiac hypertrophy and lung congestion, both attenuated by RDN. In sham-operated but not in ACF TGR, RDN significantly decreased mean arterial pressure.

CONCLUSION

The results show that RDN significantly improved survival rate in ACF TGR; however, this beneficial effect was not associated with improvement of reduced RBF or with attenuation of exaggerated renal vascular responsiveness to ANG II.