Effects of renal sympathetic denervation on myocardial structure, function and perfusion: A serial CMR study.

BACKGROUND AND AIMS: Echocardiographic studies have shown improvements in cardiac indices associated with renal sympathetic denervation (RDN), however, the benefits on myocardial perfusion have never been assessed. This trial was designed to study the effects of RDN on myocardial perfusion using cardiac magnetic resonance (CMR) imaging. METHODS: A total of 14 patients with resistant hypertension were recruited for RDN and myocardial perfusion, alongside other CMR indices, was assessed at baseline and at 6 months. RESULTS: RDN showed significant reduction of mean office blood pressures from 181/100 ±â€¯19/16 mmHg to 147/85 ±â€¯19/17 mmHg, 6 months after the procedure (p < 0.0001). This was combined with significant improvement in regional aortic distensibility (p < 0.02) and associated with trends of improved myocardial perfusion reserve index (baseline = 2.2 ±â€¯1; 6 months = 2.9 ±â€¯1 units) (p = 0.08). Left ventricular end systolic volume index decreased from baseline to 6 months post procedure, 27 ±â€¯13 ml/m2vs. 22 ±â€¯10 ml/m2 (p = 0.03), but there was no significant change in left ventricular end diastolic volume index (p = 0.09). There was significant improvement in mean left ventricular ejection fraction from 68 ± 10% to 72 + 9%, 6 months post procedure (p = 0.04). T1 mapping failed to detect fibrosis in these patients at baseline and therefore no change was noted, however, extracellular volume percent improved from 46 ±â€¯4% at baseline to 41 ±â€¯8% at 6 months (p = 0.002). CONCLUSIONS: This study demonstrates that renal sympathetic denervation increased myocardial perfusion by 32% as assessed by CMR, and, this was associated with improvements in cardiac volumes and function. Larger well controlled and randomized studies are required to assess the clinical significance of these findings.

Renal sympathetic denervation increases renal blood volume per cardiac cycle: a serial magnetic resonance imaging study in resistant hypertension.

AIM: Preclinical studies have demonstrated improvements in renal blood flow after renal sympathetic denervation (RSDN); however, such effects are yet to be confirmed in patients with resistant hypertension. Herein, we assessed the effects of RSDN on renal artery blood flow and diameter at multiple time points post-RSDN. METHODS AND RESULTS: Patients (n=11) with systolic blood pressures ≥160 mmHg despite taking three or more antihypertensive medications at maximum tolerated dose were recruited into this single-center, prospective, non-blinded study. Magnetic resonance imaging indices included renal blood flow and renal artery diameters at baseline, 1 month and 6 months. In addition to significant decreases in blood pressures (p<0.0001), total volume of blood flow per cardiac cycle increased by 20% from 6.9±2 mL at baseline to 8.4±2 mL (p=0.003) at 1 month and to 8.0±2 mL (p=0.04) 6 months post-procedure, with no changes in the renal blood flow. There was a significant decrease in renal artery diameters from 7±2 mm at baseline to 6±1 mm (p=0.03) at 1 month post-procedure. This decrease was associated with increases in maximum velocity of blood flow from 73±20 cm/s at baseline to 78±19 cm/s at 1 month post-procedure. Notably, both parameters reverted to 7±2 mm and 72±18 cm/s, respectively, 6 months after procedure. CONCLUSION: RSDN improves renal physiology as evidenced by significant improvements in total volume of blood flow per cardiac cycle. Additionally, for the first time, we identified a transient decrease in renal artery diameters immediately after procedure potentially caused by edema and inflammation that reverted to baseline values 6 months post-procedure.