Sympathetic crosstalk in the cardiorenal axis

In this thesis, the sympathetic crosstalk of the cardiorenal axis is investigated at multiple levels.
The first part explores the hemodynamic and anti-arrhythmic effects of sympathetic modulation by renal sympathetic nerve ablation (RSD). In concert with previous reports, RSD led to a significant drop in office blood pressure. However, a reduction in sympathetic activity could not be demonstrated on a cardiac level. Also, an evident anti-arrhythmic effect could not be revealed from an extensive literature search. Also, the effects of weight reduction following bariatric surgery is investigated. In morbidly obese normotensive and mildly hypertensive women, gastric bypass surgery led to an improved hemodynamic profile and the enhanced baroreflex sensitivity suggests an altered autonomic balance towards increased parasympathetic heart rate control.
The second part focuses on translating the knowledge from intracoronary hemodynamic measurements - broadly implemented in daily cardiology practice - to the identification of functionally relevant renal artery stenosis. The predictive potentials for treatment outcome of combined measurements of pressure and flow velocity is investigated. Also, we demonstrate that combined measurements of pressure and flow velocity appear feasible and reproducible. A novel method to measure intraglomerular pressure is introduced.
The holy grail would be that these measurements reflecting flow reserve and intraglomerular pressure represent a benchmark for future non-invasive measurements (e.g., computational fluid dynamics). By all means, implementation of these measurements in daily practice will have to be preceded by studies that investigate how to induce hyperaemia with absence of intravascular administration of vasodilators.