Evaluation of fluid absorption during flexible ureteroscopy in an in vivo porcine model.

OBJECTIVE: To evaluate the relationship between renal pelvis pressure and fluid absorption during ureteroscopy (URS) in a live porcine model. MATERIALS AND METHODS: Flexible URS (fURS) was performed in anaesthetised female Yorkshire pigs. Prior to performing fURS, a 0.3556-mm (0.014″) pressure-sensing guidewire (Comet™, Boston Scientific) was placed to monitor renal pelvis pressure. A simulated fURS procedure was then performed for 1 h. Infusion of irrigation fluid (5% ethanol in saline) at target renal pelvis pressures (37-150 mmHg) was maintained for 1 h using a pressure bag and real-time feedback from the pressure-sensing guidewire. Venous blood was sampled every 10 min. The volume of irrigation fluid absorbed was estimated with established equations. RESULTS: A URS procedure was performed in vivo in 18 porcine kidneys and the volume of irrigation fluid absorbed during the 1 h URS was calculated. The mean (SD) volume of irrigation fluid absorbed after 1 h of simulated URS was 7.6 (5.7), 10.8 (7.1), 26.0 (15.8), and 56.8 (22.3) mL at renal pelvis pressures of 37, 55, 75, and 150 mmHg, respectively. Compared with URS with renal pelvis pressure of 37 mmHg, the volume of fluid absorption was significantly greater at renal pelvis pressures of 75 and 150 mmHg (P = 0.026 and P = 0.047, respectively). In addition, compared with URS with renal pelvis pressure of 37 mmHg, the rate of absorption was significantly greater at renal pelvis pressures of 75 and 150 mmHg (both P < 0.001). CONCLUSION: In this study of an in vivo porcine model of URS, increasing renal pelvis pressures during URS were associated with increases in irrigation fluid absorption and increases in the rate of fluid absorption.

Two Blades-Up Runs Using the JetStream Navitus Atherectomy Device Achieve Optimal Tissue Debulking of Nonocclusive In-Stent Restenosis: Observations From a Porcine Stent/Balloon Injury Model.

PURPOSE: To determine the number of runs with blades up (BU) using the JetStream Navitus to achieving optimal debulking in a porcine model of femoropopliteal artery in-stent restenosis (ISR). METHODS: In this porcine model, 8 limbs were implanted with overlapping nitinol self-expanding stents. ISR was treated initially with 2 blades-down (BD) runs followed by 4 BU runs (BU1 to BU4). Quantitative vascular angiography (QVA) was performed at baseline, after 2 BD runs, and after each BU run. Plaque surface area and percent stenosis within the treated stented segment were measured. Intravascular ultrasound (IVUS) was used to measure minimum lumen area (MLA) and determine IVUS-derived plaque surface area. RESULTS: QVA showed that plaque surface area was significantly reduced between baseline (83.9%±14.8%) and 2 BD (67.7%±17.0%, p=0.005) and BU1 (55.4%±9.0%, p=0.005) runs, and between BU1 and BU2 runs (50.7%±9.7%, p<0.05). Percent stenosis behaved similarly with no further reduction after BU2. There were no further reductions in plaque surface area or percent stenosis with BU 3 and 4 runs (p=0.10). Similarly, IVUS (24 lesions) confirmed optimal results with BU2 runs and no additional gain in MLA or reduction in plaque surface area with BU3 and 4. IVUS confirmed no orbital cutting with JetStream Navitus. There were no stent strut discontinuities on high-resolution radiographs following atherectomy. CONCLUSION: JetStream Navitus achieved optimal tissue debulking after 2 BD and 2 BU runs with no further statistical gain in debulking after the BU2 run. Operators treating ISR with JetStream Navitus may be advised to limit their debulking to 2 BD and 2 BU runs to achieve optimal debulking.

Safety and Feasibility of a Novel Esophageal Balloon for Circumferential Cytologic Sampling.

OBJECTIVES: A prior publication introduced the Strome-Blitzer balloon's ability to obtain circumferential esophageal cytologic sampling. This GLP study was requisite for FDA approval to determine if equivalent cell capture and cellularity was observed with the balloon compared to surface sampling brushes and to determine the balloon's usability for naive otolaryngologists. METHODS: Three naïve users tested the Hobbs brush and Strome-Blitzer balloon on 4 Yorkshire swine. Four anatomical sites were sampled, beginning distally and ending proximally. In 2 animals, the balloon was used first distally and in the remaining 2, 4 new Hobbs brushes were used distally first. Moving proximally, the balloon and brushes were sequentially alternated. In follow-the-leader fashion, the balloon was introduced trans-orally followed by an endoscope to the desired site. The balloon was inflated exposing the abrasive strips to contact the esophageal mucosa. Moving the balloon 1 to 2 cm superiorly and inferiorly effected circumferential cell capture. The balloon was collapsed and removed, preserving the cellularity. The Hobbs brush was passed through the scope's channel. Four brushes, 1 per quadrant, obtained the samples at an anatomical site. The balloon was rated as pass/fail on the following: delivery, kinking, usability, and malfunction. A blinded veterinary pathologist evaluated the cytology. RESULTS: There was no device malfunction, mucosal trauma, or difficulty with device use. Balloon cytologic samples were comparable in cellularity and quality to the brush. CONCLUSION: A single balloon sampling was comparable to 4 brushes in capturing diagnostically relevant cellular volumes and architecture. Naïve users easily performed the procedures after reading the guidelines. LEVEL OF EVIDENCE: 3.