Eustachian Tube Stent

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Eustachian Tube Stent

  1. 1. Pilot study of a resorbable poly-l-lactide Eustachian Tube stent; feasibility and tolerability in two animal models JA Litner M.D., CJ Linstrom M.D., P Presti, MD, CA Silverman Ph.D., S McCormick M.D., GP Yu M.D., J Arigo M.D.
  2. 2. Middle Ear Disease Susceptibility is clearly multifactorial Hypoventilation is regarded as the root cause ET dysfunction is the principal culprit
  3. 3. Background: The Eustachian tube: *Adam Images and Content under license from adam.com, Inc., © 2002 adam.com, Inc.
  4. 4. Theories of Causality Eustachian tubes are mechanically obstructed Tubal stenosis noted in nearly half of chronic ears1 No significant post-mortem alteration in tube caliber2 Eustachian tubes are functionally obstructed Tubal hypercompliance, The Floppy Tube3 Alteration in tubal surface tension dynamics4-8 1Tos M. Journal of Laryngology and Otology 1980;94:25-30 2Sade et al. American Journal of Otology 1986;7(6) 3Bluestone CD. Head and Neck Surgery- Otolaryngology. Ch. 111; 1993 4Miura M et al. Acta Otolaryngologica. 1996;116:840-44 5Fornadley JA et al. Otolaryngology- Head and Neck Surgery. 1994;110:110-4 6Nemechek AJ et al. Otolaryngology- Head and Neck Surgery. 1997;117:475-9 7Passali D et al. Respiration. 1987;51 supp.1:52-9 8Sujana S et al. Laryngoscope. 2004:114 ; 472-485
  5. 5. Significance  Most Common Reason For Sick visits to PMD’s for Children <3  5 Billion spent annually1  One Million children undergo myringotomy annually 1  Morbidity associated with MT  Frequent returns to the OR  Over prescription of Abx and rising resistance  No Modality that specifically addresses the underlying pathophysiology: Eustachian Tube Dysfunction 1Gates GA. Otolaryngology Head Neck Surg. 1996;114:525-530 Bluestone CD. Head and Neck Surgery- Otolaryngology. Ch. 111; 1993
  6. 6. Historical Interventions ET insufflation prior to 19501 Elaborate surgical shunts, ET irradiation in 1960’s2-4 Armstrong tube invented in 19545 ―Permanent‖ vent tubes Silverstein tube6 Jahn Hydroxylvent tube7 1Shapiro SL. Eye Ear Nose and Throat Monthly. 1969;48:72-7 2Drettner B et al. Archives of Otolaryngology. 1969;90:122-8 3Goode RL et al. Laryngoscope. 1975;85:100-12 4House WF et al. Laryngoscope. 1969;79:1765-82 5Armstrong BW. Archives of Otolaryngology. 1954;59:653-4 6Silverstein H. Archives of Otolaryngology. 1970;91:313-8 7Jahn AF. Otolaryngology- Head and Neck Surgery. 1991;105(5):758-60
  7. 7. Problems with Current Approach Medical Increased antibiotic resistance Surgical Extrusion Scarring/Perforation Infection Cholesteatoma Disruption of graft healing Failure to alter natural course About 25% of procedures are repeat
  8. 8. ET Stenting Wright Jr., 1976 – Silastic Eustachian Tube Prosthesis (SETP)  Series of 138 patients with average 26 month follow- up  80% had an aerated ME behind intact TM after 6 months  Poor results after 6 months  No serious complications Wright Jr. JW et al. Laryngoscope. 1977;87:207-14 Wright Jr. JW et al. ORL. 1978;86:834-7
  9. 9. Hypothesis  Functional restoration most physiologically sensible approach  ET Stenting should augment function and restore ventilation  Success achievable through advances in biomaterials science & capacity to elute drugs  Successful applications to other hollow viscera1-6 1Korpela A et al. Chest. 1999;115:490-95 2Tamai H et al. Circulation. 2000;102:399-404 3Lumiaho J et al. Journal of Urology. 2000;164:1360-3 4Middleton JC et al. Medical Plastics and Biomaterials. 1998;March 5van Berkel A et al. Gastrointestinal Endoscopy. 2000;51:19-22 6Sung JJY. Journal of Industrial Microbiology. 1995;15:152-5
  10. 10. Stent Design Issues  Stent Deployment  Stent Retrieval  Indwelling Effects  Perforation  Migration  Occlusion  Extrusion  Ascending infection  Reflux  Autophony/Patulous symptoms  Longevity
  11. 11. Specific Aims Aim 1– Explore technical ease Aim 2– Establish safety profile Aim 3– Determine tissue response Aim 4– Assess extent of stent resorption
  12. 12. Stent Prototype Manufactured by PPD Méditech Waterville, QC
  13. 13. Stent Location
  14. 14. Methodology- Study 1  Adult Chinchilla ear model  NYMC Dept. Comp. Med. facility—IACUC approved  Sample size of 5 animals  Baseline tympanograms & otomicroscopy  Stent implanted randomly via transbullar approach  Remaining ear matched control
  15. 15. Methodology All animals treated with peri-operative systemic antibiotics Serial testing at 4,6,8,10,14,18,22,26 weeks Digital otomicro photos taken at each interval One animal sacrificed at 10, 18, & 26 weeks Temporal bones sectioned and evaluated blindly by head and neck pathologist Statistical comparison of between-group differences in ME pressures over time
  16. 16. Results 2 animals died intra-operatively due to respiratory arrest Follow-up available for 3 animals up to time of sacrifice One animal developed transient post-operative otorrhea in implanted ear via existing myringotomy incision; resolved with ototopical antibiotics
  17. 17. Otomicroscopy Baseline 4 weeks 12 weeks 26 weeks Test Ear Control Ear
  18. 18. Tympanometry 100 100 Animal #1, Control ear 75 Animal #1, Test ear 75 Peak Compliance Peak Compliance 50 50 (daPa) 25 (daPa) 25 0 0 -25 -25 -50 -50 -75 -75 -100 -100 Base 4 6 8 10 14 18 22 26 Base 4 6 8 10 14 18 22 26 Time (weeks) Time (weeks) 100 Control 100 Test Peak Compliance (daPa) Animal #2, Control ear 75 Animal #2, Test ear 75 50 Peak Compliance Peak Compliance 50 25 25 (daPa) (daPa) Ear 0 -25 -25 0 Ear -50 -50 -75 -75 -100 -100 -125 -125 Base 4 6 8 10 14 18 22 26 Base 4 6 8 10 14 18 22 26 Time (weeks) Time (weeks) 100 100 75 Animal #3, Control ear 75 Animal #3, Test ear Peak Compliance Peak Compliance 50 50 (daPa) 25 (daPa) 25 0 0 Data Points -25 -25 -50 Zero Point -50 -75 -75 -100 -100 Base 4 6 8 10 14 18 22 26 Base 4 6 8 10 14 18 22 26 Time (weeks) Time (weeks)
  19. 19. Pathology– Gross
  20. 20. Pathology– Micro N Control Ear LP C Original Magnification x 60 O B TVP
  21. 21. Pathology– Micro N C Test Ear LP Original Magnification x 60 O TVP B
  22. 22. Pathology– Micro Control Ear Test Ear G G
  23. 23. Pathology– Micro TZ C Test Ear
  24. 24. Stent Resorption
  25. 25. Data Analysis Number Mean Standard Z value† P value Peak Compliance(daPa) deviation Animal #1 Left 5 6.0 8.2 0.00 >0.05 Right 5 8.0 26.1 Animal #2 Left 9 -11.7 48.5 2.49 0.013 Right 9 -40.6 58.4 Animal #3 Left 7 8.6 22.7 1.89 0.058 Right 7 -17.9 46.4 † Wilcoxon signed ranks test.
  26. 26. Methodology- Study 2  Adult NZ White Rabbit ear model  NYMC Dept. Comp. Med. facility—IACUC approved  Sample size of 10 animals  Similar study protocol- serial otomicroscopy at 2 week intervals  All animals sacrificed at 6 months
  27. 27. Results Findings on Otomicroscopy in Test Ears Test Week Week Week Week Week Week Week Week Week Week Week Week Animal 1-2 3-4 5-6 7-8 9-10 11-12 13-14 15-16 17 –18 19-20 21 –22 23-24 #1 Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal #2 OM OM and Facial Resolved Normal Normal Normal Normal Normal Normal Normal Normal Normal Cellulitis OM #3 Normal Normal Normal Normal OM OM Normal Normal Normal Normal Normal Normal #4 Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal #5 Normal Normal OM Normal Normal Normal Normal Normal Normal Normal Normal Normal #6 Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal #7 Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal #8 OM Resolved Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal #9 Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal #10 Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal
  28. 28. Results Histologic Findings at 6 months Specimen Implanted Ear Control Ear 1 No Inflammation No Inflammation 2 No Inflammation No Inflammation 3 No Inflammation No Inflammation / Cholesteatoma 4 No Inflammation No Inflammation 5 No Inflammation No Inflammation 6 No Inflammation No Inflammation 7 No Inflammation No Inflammation 8 No Inflammation No Inflammation 9 No Inflammation No Inflammation 10 No Inflammation No Inflammation
  29. 29. Results Transient infections in 4 test ears No chronic inflammatory response in all test ears after 6-month incubation No remnants of stents noted at 6 months
  30. 30. Conclusions Stents were easily implanted Stents were well tolerated with development of transient otorrhea in few subjects Stents engendered negligible inflammatory response Differential resorption- Stents were minimally resorbed at 6 months in the Chinchilla model
  31. 31. Future Directions Technology merits further testing for efficacy Determine appropriate sterilization procedures Clarify resorption spectrum Explore use of surface agents or drug elution to improve biocompatilibity and reduce biofilm
  32. 32. Acknowledgments Dr. Ellen Levee, DVM for supervision of animal care New York Medical College DCM Staff PPD Meditech, 50 Raymond, Waterville, QC for manufacture and supply of stent prototypes
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