The “OneShot” Irrigated Balloon-Mounted Spiral Electrode Renal Denervation Device

Fig. 11.1

The OneShot irrigated RF renal sympathetic denervation system In (a) is depicted the OneShot balloon with the spiral electrode indicated by the asterisks. The black arrows indicate the eight irrigation holes in the balloon adjacent to the electrode. The balloon is delivered over a 0.014 in. wire (white arrow). The diagram in (b) is a left renal artery cutaway showing the inflated balloon and with the spiral electrode in an orange colour. The sympathetic nerves are shown in yellow. Shown in (c) is a left renal selective angiogram showing the position of the OneShot in this artery. In (d) the balloon is inflated and occludes the renal artery indicating the likelihood of apposition of the electrode to the arterial wall. In (e) is shown saline irrigation from the balloon holes (Reprinted from Ormiston [9] with permission from Europa Digital & Publishing)

The RFG features a touch screen interface for user input and displays instructional messages and procedural feedback such as power delivered, impedance, and remaining treatment time. The RFG displays warning messages and triggers automatic shut-offs to ensure safe operation of the system [8].

The Renal Hypertension Ablation System (RHAS) Trial [9]

The aims of this first-in-human study were to provide hypothesis generating safety and feasibility data concerning the OneShot renal denervation device.

Endpoints

The primary endpoint was the successful insertion and positioning of the OneShot balloon in each renal artery and delivery of low level radiofrequency energy. Secondary endpoints included: (1) acute procedural safety, defined as absence of serious groin complications or vascular access site complications; (2) procedural success, defined as freedom from complications associated with the delivery and/or use of the OneShot Device or the procedure; and (3) blood pressure lowering effects of the procedure measured by the reduction of office systolic blood pressure at 6 months compared with baseline.

Patients

The inclusion and exclusion criteria were similar to those of the Symplicity HTN trials [1, 2]. Patients 18 years and older were suitable for enrollment if they had a consistent office measured systolic BP greater than or equal to 160 mmHg (or greater than 150 mmHg for patients with type 2 diabetes) despite treatment with two or more antihypertensive medications and had renal artery diameters between 4 and 7 mm. Patients were excluded if they had a glomerular filtration rate less than 45 mL/min/1.73 m [2]. Before ablation, all patients underwent computed tomography angiography (CTA) to exclude those with inappropriate renal artery diameters, multiple large arteries, early arterial division, more than mild renal artery stenosis, and serious renal abnormalities.

Follow-up

Patient assessments were carried out before the procedure and at 1, 3, 6 and 12 months follow-up. At each follow-up office blood pressure was measured, medications reviewed and potential adverse events assessed.

Study Management

Data were independently monitored to ensure compliance with the protocol and to verify that the data matched source medical records. An independent Clinical Events Committee adjudicated study endpoints and events that occurred throughout the study. The Data and Safety Monitoring Board reviewed all safety issues.

Statistical Analysis

This study was hypothesis generating and designed to provide initial performance information for the OneShot device. The sample size was not defined on the basis of an endpoint hypothesis. Descriptive statistics were provided for baseline demographics, procedural characteristics, and study outcomes. Continuous variables are expressed as mean (standard deviation) and discrete variables as percentages. Given the small sample size, changes in blood pressure were evaluated using paired t-tests. A P value of <0.05 was used as the cut-off was indicative only hence corrections for multiple t-tests were not made. All statistical analyses were performed using Statistical Analysis System (SAS) for Windows version 9.2 (SAS Institute Inc. Cary, NC).

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