Page 44 - BH-1-2

Brain & Heart RDN guided by novel blood pressure responses

systemic sympathetic tone. Recently, it was considered filtration rate of <45 mL/min per 1.73 m . Medication
2
an effective option in the management of hypertension. regimens, ambulatory BP (ABP) monitoring, office BP
Although the neutral results of several randomized sham- (OBP), renal artery computed tomography angiography,
controlled trials questioned the effectiveness of RDN [1-3] , and estimated glomerular filtration rate were recorded at
posthoc analysis and the final report of the hypertension-3 baseline and follow-up periods. Measuring BP (BP) every
(HTN-3) trial suggested that it can cause a significant 20 min during the day and 1 h at night was used in the
reduction of office and ambulatory blood pressure ABP monitoring. The electronic sphygmomanometer
(ABP) [4,5] . Coincidentally, recent trials with state-of-the- (Intellisense, HEM-7130, OMRON, Dalian, China)
art methodology reconfirmed the real antihypertensive was used to obtain the OBP (average values of triplicate
effect of RDN [6-9] . Meanwhile, nearly 30% of patients with measures). All patients were willing to complete the
hypertension did not respond to RDN treatment, even interventional procedure and provided informed consent.
with their BP rising instead of falling. We believe that the This study was approved by the hospital’s ethics committee.
cause of this phenomenon should be closely related to renal
nerve function. Since the current ablation strategy is based 2.2. RDN Procedure
on the anatomical distribution of renal nerves, it is not Every patient underwent bilateral renal arteriography,
considered that renal nerves may also have the function high-frequency RNS, and catheter-based radiofrequency
of lowering BP in addition to raising BP. Therefore, the ablation. The surface ECG was continuously recorded
anatomical destruction of renal nerves potentially results throughout the procedure by a multichannel recorder
in this heterogeneity of postoperative BP response . (Sichuan Jinjiang Electronic Science and Technology
[10]
Selective ablation of the sites with suitable renal nerves may Company, Chengdu, China). The right femoral artery
be a key to further improving the effectiveness of RDN. was punctured under sterile conditions, and 50 IU/kg
Previous studies suggested that various BP responses, of unfractionated heparin was administered. A 6F JR4
including elevation, drop, and no change, can be induced Judkins catheter (Cordis Corporation, Miami, Florida) was
by renal nerve stimulation (RNS) [11-14] , which is in line with used to perform angiography via the right femoral artery.
the different physiological functions of various renal nerve The invasive BP monitoring continuously recorded the
fibers located in one nerve bundle [10,15,16] . Based on these patient’s BP through the left/right radial artery. Intravenous
results, we speculated that the patterns of BP response application of fentanyl (initial injection with 0.002 mg/kg
evoked by RNS depend on the synthetical effects of and continuous intravenous infusion with 0.002 mg/kg/h)
different renal nerve fibers . In other words, the detailed was used for analgesia. A dedicated 6F bipolar micropores
[17]
BP response might assist in assessing the innervation at the irrigated ablation catheter (AquaSense, Synaptic Medical
stimulated sites, and this is important for effective ablation. Limited, Beijing, China) was deployed in the renal artery
Recently, our team reported five patterns of BP response via the right femoral artery.
and found that ablation at the sites with BP elevation led to High-frequency bipolar electrical stimulation was
efficient BP lowering in the canine [18,19] . However, whether performed orderly from the bifurcation (if the diameters of
there were similar responses in humans was unclear. The renal branches and the accessory renal arteries were more
aims of this study were to identify the BP responses induced than 3.5 mm, RNS was also permitted to deliver) to the
by RNS and use these responses to guide the selection of ostium of the renal artery via the saline-irrigated electrode
effective targets for RDN in patients with hypertension. using a nerve and muscle stimulator (SynNuo-C4, Sichuan
Jinjiang Electronic Science and Technology Company,
2. Materials and methods Chengdu, China). Electrical stimulation was delivered
2.1. Patient population with a frequency of 10 Hz, a current of 15 mA, and a pulse
In our center, renal electrical stimulation mapping was width of 2 ms for 30 s. The sites with an elevation of systolic
performed meticulously in the first 14 patients with BP (SBP) >5 mmHg during RNS were ablated using the
resistant hypertension. Patients were eligible if their same catheter. After ablation, the position of the electrode
was unchanged, and electrical stimulation was performed
average ambulatory systolic BP was ≥130 or their diastolic
BP was ≥80 mmHg after receiving and adhering to at least again with the same parameters.
three antihypertensive drugs (except when not tolerated). Radiofrequency-based ablation was performed at the
Exclusion criteria included abnormal anatomy of the renal sites with the SBP elevation during RNS. The temperature
artery, severe renal stenosis, stent implantation in the renal of the intima-electrode interface was decreased through
artery, identification of secondary hypertension or type 1 the 6–8 ml/min saline irrigated manually during
diabetes mellitus, pregnancy, and an estimated glomerular radiofrequency delivery. Conventional radiofrequency

Volume 1 Issue 2 (2023) 2 https://doi.org/10.36922/bh.0384