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The blood pressure (BP) response to renal denervation (RDN) is highly variable. In addition, the changes in renal artery (RA) dimensions induced by RDN have rarely been quantified and never been related to BP changes.
We investigated RAs of 16 patients (7 females, 11 diabetics, mean age 62.6 years) pre and post RDN (Symplicity Flex in 9 pts, Symplicity Spyral in 7 pts; both Medtronic Inc) with intravascular ultrasound (Atlantis pro, Boston Scientific iLab). IVUS images were analyzed with QCU-CMS research software (LUMC) yielding global measures of RA size (RA vessel volume VV, lumen volume LV, wall volume WV), and measures of most pronounced focal changes (minimum and maximum vessel area VA, lumen area LA and wall burden WB) - Figure. Patients were followed with office and 24 hour blood pressure monitoring at month 1, 3, 6, and 12.
Pre RDN, 24 hour BP was 153/88 mm Hg, mean number of ablation points was 11.3 (SD 3.4). After 1, 3, 6, and 12 months, 24 hour BP decreased by 12/7, 6/4, 17/9, and 21/11 mm Hg, respectively. RDN induced a non-significant decrease in RA vessel volume of 5.6 (SD 9.8) %, a significant decrease of RA lumen volume of 8.8 (SD 10.7)%, and a non-significant increase of RA wall volume of 6.1 (SD 10.9) %. Max and min LA decreased significantly by 7.3 (SD 9.4) and 10.5 (14.3) %, respectively, as did min VA by 7.1 (12.5) %. Max vessel area and min and max wall burden did not change significantly. Women had smaller RAs, which was related to their lower body height. Changes in RA size were similar between men and women, as were changes in blood pressure. ABPM-based BP change at 1 (SBP, DBP), 3 (SBP, DBP), 6 (DBP) and 12 (DBP) months was significantly and directly related to changes in min LA and min VA (correlation coeffficients 0.63-0.80, p-values 0.002-0.02). At 1 year, decrease in SBP was related to increase in wall volume post RDN (r= -0.88, p=0.004). Patients with a decrease in minimal VA post RDN above the median had a significantly better BP response at 1 and 3 months. Patients with an increase in WV post RDN had a significantly better SBP response at 6 and 12 months.
RDN leads to effects on RA dimensions (decrease in vessel and lumen size, increase in wall thickness), which can be quantified by IVUS. A higher degree of changes may be associated with a better BP response to the procedure.
ENDOVASCULAR: Hypertension Therapies and Renal Denervation