scholarly journals Efficacy of radiofrequency RDN may be significantly improved if the procedure is guided by impedance drop during the treatment

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
S Pekarskiy ◽  
A Baev ◽  
M Tarasov ◽  
V Mordovin ◽  
A Falkovskaya ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Nerve Injury ◽  
Structural Changes ◽  
Significant Proportion ◽  
Experimental Studies ◽  
Renal Nerves ◽  
Optical Coherence ◽  
Renal Nerve ◽  
Small Depth ◽  
Superficial Tissue

Abstract Background Experimental studies of radiofrequency renal denervation (RDN) have shown a strong relation of the depth of structural lesions and completeness of renal nerve injury to the relative drop in impedance during the treatment caused by the increased permeability of the cell membranes. Thus, the otherwise successful treatments but with low impedance drop may be, in fact, totally ineffective. Objective We assessed the relation between impedance drop during single radiofrequency treatments and local structural changes of vascular wall at the electrode positions using optical coherence tomography. Methods Optical coherence tomography of the treated segments was performed during radiofrequency RDN in 14 patients with resistant hypertension. The parameters of contrast injection depended on the position of the guiding catheter: for selective branch imaging 15 ml volume was injected at 8 ml/sec speed; otherwise 30 ml of contrast was injected at the speed 15 ml/sec to flush the whole renal artery. Automatic pullback of the sensor was done with the standard speed 20 mm/sec. In total, 423 mm of treated segments in 22 renal vessels (mostly distal branches) had sufficient quality of imaging and were studied for structural changes. Results There was almost no local structural changes of the arterial wall after the treatments with low impedance drop <10% reflecting a rather weak heating of even superficial tissue layers. No effect on the deeper tissue layers is expected in this case because these layers are heated almost exclusively by the heat transfer from superficial layer. In contrast, the treatments with the impedance drop 10% or greater were able to significantly affect the arterial structure causing local edema, small dissections, and local thrombi formation as a result of significant resistive heating of the superficial tissue, and, therefore, high potential for heating of the deep layers containing the renal nerves. Only approximately 40% of the point treatments had the impedance drop 10% or greater suggesting adequate lesion depth and sufficient completeness of renal nerve injury. This may indicate a rather low procedural efficacy of the current mode of radiofrequency RDN due to a large proportion of small-depth treatments marked by only a few percent decrease in impedance yet considered fully “successful”. Also, it means a potential for significant increase in the efficacy of radiofrequency RDN through controlling/guiding the treatment by the impedance drop. Conclusion Our study shows that variable efficacy of radiofrequency RDN may be explained by a significant proportion of the small-depth point treatments ineffective in terms of renal nerve injury, and, thereby, may be significantly improved if the procedure is guided by the impedance drop during the treatment. Funding Acknowledgement Type of funding source: None

scholarly journals Choroidal vessel density in unilateral hyperopic amblyopia using en-face optical coherence tomography

2020 ◽  
Author(s):  
Syunsuke Araki ◽  
Atsushi Miki ◽  
Katsutoshi Goto ◽  
Tsutomu Yamashita ◽  
Tsuyoshi Yoneda ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Normal Control ◽  
Structural Changes ◽  
Vascular Density ◽  
Optical Coherence ◽  
Swept Source ◽  
3 Dimensional ◽  
Face Images ◽  
En Face ◽  
Normal Controls

Abstract Background Structural changes of the choroid, such as choroidal thickening, have been indicated in amblyopic eyes with hyperopic anisometropia as compared to fellow or healthy eyes. The purpose of the present study was to investigate choroidal vascular density (CVD) in children with unilateral hyperopic amblyopia.Methods This study included 88 eyes of 44 patients with unilateral amblyopia due to hyperopic anisometropia with or without strabismus and 29 eyes of 29 age-matched normal controls. The CVD of Haller's layer was quantified from en-face images constructed by 3-dimensional swept-source optical coherence tomography images flattened relative to Bruch's membrane. The analysis area was a 3×3-mm square of macula after magnification correction. Relationships between CVD and other parameters [best-corrected visual acuity (BCVA), refractive error and subfoveal choroidal thickness (SFCT)] were investigated, and CVDs were compared between amblyopic, fellow, and normal control eyes.Results Mean CVD was 59.11 ± 0.66% in amblyopic eyes, 59.23 ± 0.81% in fellow eyes, and 59.29 ± 0.74% in normal control eyes. CVD showed a significant positive relationship with SFCT (p=0.004), but no relationships with other parameters. No significant differences in CVD were evident among amblyopic, fellow, and normal control eyes after adjusting for SFCT (p=0.502).Conclusions CVD was unrelated to BCVA, and CVD did not differ significantly among amblyopic, fellow and normal control eyes. These results suggest that the local CVD of Haller's layer is unaffected in unilateral hyperopic amblyopic eyes.

scholarly journals Glaucomatous Macular Vasculature: A Quantitative Analysis

2020 ◽  
Vol 9 (3) ◽  
pp. 185-197
Author(s):  
Pedro Arede ◽  
Joanna Przezdziecka-Dolyk ◽  
Fabian Debowy ◽  
Jacek Olszewski ◽  
Carla Fernandes ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Structural Changes ◽  
Open Angle Glaucoma ◽  
Major Axis ◽  
Foveal Avascular Zone ◽  
Control Group ◽  
Equivalent Diameter ◽  
Optical Coherence ◽  
Fiber Layer ◽  
Avascular Zone

Background: The aim of this study was to evaluate the characteristics of the macular vessel density (VD) and the foveal avascular zone (FAZ) in glaucoma quantitatively using the optical coherence tomography angiography (OCT-A). Methods: Twenty-five eyes of 13 patients with primary open angle glaucoma (POAG) and 12 eyes of 6 healthy participants were enrolled retrospectively. Functional visual field (VF) and structural Spectral-Domain optical coherence tomography (SD-OCT) Retinal Nerve Fiber Layer Thickness (RNFLT) were assessed in all participants. OCT-A was performed on a fovea centered, 15x10 degrees, macular region. OCT-A scans were processed with MATLAB software and automatically graded to define FAZ parameters. The parafoveal VD in the superficial and deep retinal vascular plexus (SVP and DVP) was analyzed by quadrant and circular segmented zones. Results: Foveal Avascular Zone -Major Axis Length (p=0.02), Area (p=0.04), Equivalent Diameter (p=0.04) and Perimeter (p=0.04) were significantly larger in glaucoma than the control group. Regarding SVP and DVP, the average macular total VD were lower in glaucoma patients compared to the control group (p<0.01; p<0.01). Additionally, the inner circular region (p=0.04; p<0.01 respectively for SVP and DVP) and all quadrants except for North had a lower VD in glaucoma group compared to the control group. Assessment of the total VD successfully predicted RNFLT (p<0.001) and was significantly associated with the probability of glaucoma (p=0.009). Conclusion: OCT-A parameters, namely the FAZ morphology and the macular VD, were associated with glaucomatous functional and structural changes. The macular VD showed a considerable diagnostic value. It may be a modern biomarker, representing microvascular network disruption of the macular perfusion in glaucoma.

Abstract 5999: Optical Coherence Tomography Findings At Two Years Follow Up In Fully Biodegradable Everolimus Eluting Stents

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Nieves Gonzalo ◽  
Patrick W Serruys ◽  
Rafael Freire ◽  
Jurgen Ligthart ◽  
Wim vd Giessen ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Vessel Wall ◽  
Structural Changes ◽  
Optical Coherence ◽  
Very Late Stent Thrombosis ◽  
Degradable Polymer ◽  
Full Dataset ◽  
Biodegradable Stents ◽  
Time Of Presentation

Fully biodegradable stents may avoid the potential long-term complications of metallic drug-eluting stents such as late and very late stent thrombosis. We sought to evaluate the structural changes in a bioabsorbable DES and its interaction with the coronary vessel wall over time using optical coherence tomography (OCT). We investigated 14 consecutive patients undergoing implantation of a bioabsorbable everolimus-eluting coronary stent (BVS: Abbott Laboratories, IL, USA), composed of a poly-L-lactic acid backbone, coated with a degradable polymer/everolimus matrix. OCT (LightLab Imaging, Inc., Westford, MA) was performed immediately after stent implantation, at 6 months and at 24 months follow-up. All patients tolerated OCT imaging without complications. At baseline, OCT could detect the interface between the BVS stent and other tissues or fluid, but the inside of the strut appeared black, giving a unique box appearance. After 6 months, the struts were still clearly visible; however, their optical properties had changed considerably. In patients undergoing two years follow up (n=5, full dataset will be available at time of presentation) the majority of struts was not visible anymore and all visible struts were embedded into the vessel wall with complete tissue coverage. In contrast to 6months follow-up, at 2 years no intraluminal thrombi or dissections were visible. At 2 years follow-up the majority of stent struts were not visible by OCT. All the visible struts were covered and apposed. The lumen surface was smooth without intraluminal thrombi or dissections.

scholarly journals Longitudinal assessment of optic nerve head changes using optical coherence tomography in a primate microbead model of ocular hypertension

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Anita S. Y. Chan ◽  
Tin Aung Tun ◽  
John C. Allen ◽  
Myoe Naing Lynn ◽  
Sai Bo Bo Tun ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Optic Nerve ◽  
Ocular Hypertension ◽  
Optic Nerve Head ◽  
Structural Damage ◽  
Structural Changes ◽  
Lamina Cribrosa ◽  
Optical Coherence ◽  
Longitudinal Assessment ◽  
The Mean

Abstract In humans, the longitudinal characterisation of early optic nerve head (ONH) damage in ocular hypertension (OHT) is difficult as patients with glaucoma usually have structural ONH damage at the time of diagnosis. Previous studies assessed glaucomatous ONH cupping by measuring the anterior lamina cribrosa depth (LCD) and minimal rim width (MRW) using optical coherence tomography (OCT). In this study, we induced OHT by repeated intracameral microbead injections in 16 cynomolgus primates (10 unilateral; 6 bilateral) and assessed the structural changes of the ONH longitudinally to observe early changes. Elevated intraocular pressure (IOP) in OHT eyes was maintained for 7 months and serial OCT measurements were performed during this period. The mean IOP was significantly elevated in OHT eyes when compared to baseline and compared to the control eyes. Thinner MRW and deeper LCD values from baseline were observed in OHT eyes with the greatest changes seen between month 1 and month 2 of OHT. Both the mean and maximum IOP values were significant predictors of MRW and LCD changes, although the maximum IOP was a slightly better predictor. We believe that this model could be useful to study IOP-induced early ONH structural damage which is important for understanding glaucoma pathogenesis.

Macular capillary plexuses after macular hole surgery: an optical coherence tomography angiography study

2017 ◽  
Vol 102 (7) ◽  
pp. 966-970 ◽  
Author(s):  
Yoon Jeon Kim ◽  
Jaehyuck Jo ◽  
Joo Yong Lee ◽  
Young Hee Yoon ◽  
June-Gone Kim
Keyword(s):  
Optical Coherence Tomography ◽  
Macular Hole ◽  
Structural Changes ◽  
Foveal Avascular Zone ◽  
Vascular Density ◽  
Optical Coherence ◽  
Foveal Thickness ◽  
Functional Changes ◽  
Spectral Domain Oct ◽  
En Face

AimsTo investigate the structural changes of the superficial capillary plexuses (SCP) and deep capillary plexuses (DCP) using optical coherence tomography (OCT) angiography (OCTA) in patients with idiopathic macular hole (MH) after surgery, determine the factors related to changes of macular capillary plexuses and evaluate its association with postoperative visual outcomes.MethodsThirty-three patients with unilateral MH who were followed for ≥6 months after surgery were included. Ophthalmologic evaluations included best corrected visual acuity (BCVA) and spectral-domain OCT before surgery and 6 months postsurgery. En face OCTA images were obtained for both eyes at 6 months postsurgery, and the postoperative foveal avascular zone (FAZ) area and parafoveal vascular density were identified.ResultsCompared with fellow eyes, eyes after MH surgery had a smaller FAZ area in both SCP and DCP (p<0.05 for all). The FAZ area was positively correlated with postoperative foveal thickness of the whole, inner and outer layers (p<0.05 for all). In the parafoveal region, eyes after MH surgery had a tendency to have lower parafoveal vascular density, particularly in DCP (p=0.019). The parafoveal vascular density in DCP was positively correlated with retinal thickness of the whole, inner and outer layers (p<0.05 for all). Correlations between BCVA and FAZ area in both SCP and DCP were significant 6 months after MH surgery (p<0.05 for all).ConclusionAssessment of macular capillary plexuses using OCTA may be useful for monitoring retinal structural and functional changes in MH.

Sign in / Sign up

Export Citation Format

Share Document