Zero-Contrast Percutaneous Renal Denervation Guided by Multimodal Image Fusion

Abstract

As a second-line treatment for resistant hypertension or uncontrolled hypertension, renal denervation (RDN) has been widely adopted globally. Conventional RDN procedures require the use of contrast agents, which pose risks of exacerbating renal impairment and increasing cardiac burden for patients with concurrent renal or cardiac insufficiency. A 43-year-old man, diagnosed with hypertension for >10 years, presents with combined chronic kidney disease stage 3 and heart failure. Despite standardized medication therapy, his blood pressure remains poorly controlled. Due to concerns from the patient and his family regarding the risk of contrast-induced nephropathy, our team successfully performed a zero-contrast RDN procedure by integrating magnetic resonance angiography with digital subtraction angiography imaging, guided by transabdominal ultrasound. This approach is safe, feasible, and reproducible, effectively avoiding the potential hazards associated with contrast agents, thereby aiming to improve patient prognosis more effectively.

Graphical Abstract

The 2023 European Society of Cardiology guidelines list percutaneous renal denervation (RDN) as a secondary treatment option for resistant hypertension or uncontrolled hypertension. Currently, >100,000 patients worldwide have undergone RDN. However, in clinical practice, patients with contrast agent allergies or contrast-induced kidney injury are frequently encountered. To avoid such risks, our team successfully performed a zero-contrast RDN procedure guided by multimodal image fusion.

Take-Home Messages

• •Multimodal image fusion-guided renal denervation without contrast agents is safe, feasible, and reproducible.
• •Multimodal image fusion-guided renal denervation without contrast agents offers a new treatment option for patients with hypertension complicated by renal insufficiency and/or cardiac insufficiency, and for those with contrast agent allergies.

Case Presentation

A 43-year-old man with hypertension for >10 years, with a maximum blood pressure of 210/150 mm Hg, was regularly taking sacubitril/valsartan 200 mg once daily, arotinolol 10 mg twice daily, nifedipine controlled-release tablets 30 mg once daily, and spironolactone 20 mg once daily; however, his blood pressure remained poorly controlled. Over the past year, he experienced recurrent episodes of shortness of breath without apparent cause, which worsened after activity. In the past half month, he was admitted due to paroxysmal nocturnal dyspnea. Physical examination included the following: blood pressure 122/91 mm Hg, heart rate 85 beats/min, scattered wet rales in both lungs, apical impulse located 1 cm outside the intersection of the left sixth intercostal space and the midclavicular line, no thrills palpated, no extra heart sounds or murmurs, and no edema in both lower limbs. Laboratory tests included the following: N-terminal pro–B-type natriuretic peptide 2,023 pg/mL, creatinine 177 μmol/L, estimated glomerular filtration rate 38.90 mL/min, urine microalbumin 236 mg/L (normal range: 0-25 mg/L), and urine microalbumin/creatinine ratio 296.9 mg/g (normal <30 mg/g). Cardiac ultrasound included the following: left atrial anterior-posterior diameter 43 mm (normal: 0-38 mm), left ventricular (LV) anterior-posterior diameter in diastole 63 mm (normal: 0-55 mm), interventricular septum thickness 13 mm (normal: 0-11 mm), LV posterior wall thickness 12 mm (normal: 0-11 mm), LV ejection fraction 37% (normal: 50%-80%), LV fractional shortening 18% (normal: >25%), and generalized hypokinesia of the LV wall. Considering the patient's cardiac and renal insufficiency, and to avoid the burden of contrast agents on the heart and kidneys, we opted to perform zero-contrast RDN under real-time fusion of renal artery magnetic resonance angiography (MRA) and digital subtraction angiography (DSA) images, guided by renal artery color Doppler ultrasound.

The procedure was as follows:

• 1.Inflow inversion recovery MRA was performed (CE Signa Premier 3.0T, GE Healthcare), which indicated that the patient had no subsequent branch vessels outside the renal hilum in either the left or right renal artery, and no accessory renal arteries; both renal arteries originated at the upper border of the second lumbar vertebra. The respiratory-triggered axial image inflow inversion recovery MRA 1.3-second sequence was imported into Syngo Workplace (Siemens Healthineers).
• 2.The patient lay supine on the Siemens Artis Q with PURE DSA table (Siemens Healthineers), and a 6-second DSA body fluoroscopy was performed. The images from the respiratory-triggered axial image inflow inversion recovery MRA 1.3-second sequence were merged with the fluoroscopy images using Syngo Workplace. First, the renal contours on the coronal plane were aligned (Figure 1A), then the abdominal aorta and renal contours on the axial plane were aligned (Figure 1B). The MRA images were used for 4-dimensional reconstruction, with window width adjusted to 281 and Window center to 1,211 in this case. Soft tissues were manually subtracted, leaving only the abdominal aorta-renal arteries-kidneys image for live fusion (Figure 1C). The overlay bending value was adjusted (0.15 in this case) to ensure that the MRA image clearly guided the catheter and wire direction without compromising the clarity of the DSA fluoroscopy image (Figure 1D).
• 3.The renal artery ostium indicated by the MRA image was accessed by guiding a RDC guiding catheter (GC) (Medtronic, Inc) with a J-wire. The GC was advanced into the renal artery under the guidance of radiograph, and verified by transabdominal ultrasound (Video 1).
• 4.Under the guidance of the MRA image, a Thunder wire (Medtronic, Inc) was advanced through the GC to the distal segment of the renal artery. A Symplicity Spyral ablation catheter (Medtronic, Inc) was then advanced along the Thunder wire. Ablation was performed from the renal hilum to the renal artery ostium, with 11 successful ablation points on the right side and 5 successful ablation points on the left side (Video 2).

Figure 1.

Fusion of MR Images With DSA Images

(A) Align the renal contours of the magnetic resonance (MR) image with those of the digital subtraction angiography (DSA) image on the coronal plane. (B) On the axial plane, align the contours of the kidneys and abdominal aorta from the MR image with those from the DSA image. (C) Four-dimensional reconstruction of abdominal aorta and kidney MR images. (D) Real-time fusion of MR images and DSA images.

Discussion

RDN is a safe and effective treatment for resistant or uncontrolled hypertension, having received Food and Drug Administration approval in late 2023. The 2024 clinical practice guidelines for the management of hypertension in China also classify it as a class IIb recommendation.¹ Furthermore, as research advances, the clinical benefits of RDN for patients with reduced ejection fraction heart failure are increasingly being validated. RDN can improve LV ejection fraction, reduce N-terminal pro–B-type natriuretic peptide levels, and increase 6-minute walking distance.^2,3 For this patient with hypertension, renal insufficiency, and cardiac insufficiency, RDN is undoubtedly one of the preferred treatment options. Although RDN itself does not adversely affect renal or cardiac function,⁴ the use of contrast agents carries the risk of worsening renal function and increasing cardiac burden, particularly in patients with both renal insufficiency and heart failure. Therefore, our research team successfully performed zero-contrast RDN by integrating MRA and DSA imaging with transabdominal ultrasound guidance. This approach aims to reduce procedure risks and provide greater clinical benefits for such patients.

Limitations

This RDN procedure has several limitations. First, the approach effectively guides ablation of the main vessel and branches outside the renal hilum. However, because intrahilar vascular branches are not clearly visualized, it is not recommended for guiding ablation of intrahilar branches. Studies have shown that the density of nerves was highest in the proximal segments and decreased progressively along the length of the arteries to the distal postbifurcation segments.⁵ Therefore, the efficacy of RDN is unlikely to be significantly compromised. Second, fluoroscopy inevitably increases radiation exposure, as demonstrated in this case (approximately 193 mGy). Finally, patient movement must be strictly restricted after fluoroscopy to avoid errors in image fusion; however, such errors can be corrected through a second alignment using 4-dimensional images.

Funding Support and Author Disclosures

The authors have reported that they have no relationships relevant to the contents of this paper to disclose.

Appendix

Video 1

Advancement of the RDC Catheter (“Equal Sign”) From the Abdominal Aorta Into the Renal Artery, Which Was Verified by Transabdominal Ultrasound

Video 2

Reconstructed Magnetic Resonance Images Were Fused in Real Time With Digital Subtraction Angiography Images to Guide the Symplicity Spyral Catheter Into the Left Renal Artery for Renal Denervation