Left atrial appendage occlusion

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Left atrial appendage occlusion
Intervention
ICD-9-CM 37.36
The left atrial appendage is the windsock-like structure shown to originate from the left atrium (three o'clock).

Left atrial appendage occlusion is a treatment strategy to prevent blood clot formation in patients suffering from atrial fibrillation (AF). In this heart rhythm disorder, blood clots form in the left atrial appendage (LAA) in 10-20 % of cases.[1] During cardiac catheterization, an expandable nitinol frame can be introduced into the appendage.

LAA occlusion can be used as an alternative for patients who cannot use oral anticoagulants such as warfarin, although it has been studied and approval is sought as an alternative in patients who are eligible for oral anticoagulants. Some patients can not take anticoagulants because of a recent or previous bleeding, non-compliance or pregnancy (17% in one study[2]). A sizeable portion of patients (21% in the above mentioned study[2]) eligible for anticoagulants are not offered them, or are not taking them. This applies particularly to the elderly, although studies have indicated that they can also benefit from anticoagulants.[3]

Devices and alternatives[edit]

On April 23, 2009 an U.S. Food and Drug Administration Advisory panel voted 7 to 5 in favor of approval of the WATCHMAN device (by Atritech Inc., Plymouth, Minnesota) for use in patients with non-valvular AF in centers with heart surgery backup.[4] The panel also advised creation of a registry and a certification program for physicians who implant the device. This decision was based on the results of the PROTECT-AF trial[5] (presented at the 2009 American College of Cardiology Scientific Sessions[6]), which showed less hemorrhagic stroke with the device compared to treatment with warfarin; stroke and all-cause mortality outcomes were non-inferior.

Another device termed PLAATO (percutaneous left atrial appendage transcatheter occlusion) was the first LAA occlusion device,[7][8] although it is no longer being developed by its manufacturer (Appriva Medical, Inc. from Sunnyvale, CA). In 210 patients receiving the PLAATO device, there was an estimated 61% reduction in the calculated stroke risk.[9]

Both LAA occlusion systems are introduced into the right atrium and are then passed into the left atrium through a patent foramen ovale or through a puncture hole. These small iatrogenic atrial septal defects usually disappeared within six months.[10][11] Although these are catheter-based techniques, they are generally performed under general anaesthesia.

The Amplatzer device, used to close atrial septal defects, has also been used to occlude the left atrial appendage.[12][13] This can be performed without general anaesthesia and without echocardiographic guidance. Transcatheter patch obliteration of the LAA has also been reported.[10]

Other devices exhist to occlude the left atrial appendage from the inside of the heart such as the Wavecrest device [14] and the Lariat device.[15] The latter technique entails closing a strangling noose around the LAA, which is advanced from the chest wall with a special sheath, after introducing a balloon in the LAA from the inside surface of the heart (endocardium)

The LAA can also be surgically removed simultaneous with other cardiac procedures such as the maze procedure or during mitral valve surgery.[16][17] Finally, the left atrial appendage has been closed in a limited number of patients using a chest keyhole surgery approach.[18][19]

Adverse events and limitations[edit]

The main adverse events related to this procedure are pericardial effusion, incomplete LAA closure, dislodgement of the device, blood clot formation on the device requiring prolonged oral anticoagulation, and the general risks of catheter-based techniques (such as air embolism).[20] The left atrium anatomy can also preclude use of the device in some patients.[21]

Following implantation, a transesophageal echocardiography has to be performed to judge completeness of closure and the presence of blood clots. Patients need to use low dose aspirin indefinitely, and prolonged clopidogrel can be prescribed as well; oral anticoagulants are needed following implantation of the WATCHMAN device to allow blood vessel lining to form around the device (endothelialization).

Theoretical concerns surround the role of the LAA in thirst regulation and water retention because it is an important source of atrial natriuretic factor.[22][23] Preserving the right atrial appendage might attenuate this effect.[24]

Footnotes[edit]

  1. ^ Blackshear JL, Odell JA (February 1996). "Appendage obliteration to reduce stroke in cardiac surgical patients with atrial fibrillation". Ann. Thorac. Surg. 61 (2): 755–9. doi:10.1016/0003-4975(95)00887-X. PMID 8572814. 
  2. ^ a b Gottlieb LK, Salem-Schatz S (September 1994). "Anticoagulation in atrial fibrillation. Does efficacy in clinical trials translate into effectiveness in practice?". Arch. Intern. Med. 154 (17): 1945–53. doi:10.1001/archinte.154.17.1945. PMID 8074598. 
  3. ^ Mant J, Hobbs FD, Fletcher K, et al (August 2007). "Warfarin versus aspirin for stroke prevention in an elderly community population with atrial fibrillation (the Birmingham Atrial Fibrillation Treatment of the Aged Study, BAFTA): a randomised controlled trial". Lancet 370 (9586): 493–503. doi:10.1016/S0140-6736(07)61233-1. PMID 17693178. 
  4. ^ Michael O’Riordan. FDA Advisory Panel Votes 7 to 5 to Recommend Approval of Watchman LAA Closure Device. Heartwire (Medscape), April 23, 2009.
  5. ^ Fountain RB, Holmes DR, Chandrasekaran K, et al (May 2006). "The PROTECT AF (WATCHMAN Left Atrial Appendage System for Embolic PROTECTion in Patients with Atrial Fibrillation) trial". Am. Heart J. 151 (5): 956–61. doi:10.1016/j.ahj.2006.02.005. PMID 16644311. 
  6. ^ Susan Jeffrey. ACC 2009: PROTECT-AF: Device Closure of LAA May Provide Alternative to Warfarin to Prevent Stroke in AF. Medscape Medical News. March 28, 2009.
  7. ^ Sievert H, Lesh MD, Trepels T, et al (April 2002). "Percutaneous left atrial appendage transcatheter occlusion to prevent stroke in high-risk patients with atrial fibrillation: early clinical experience". Circulation 105 (16): 1887–9. doi:10.1161/01.CIR.0000015698.54752.6D. PMID 11997272. 
  8. ^ Ostermayer SH, Reisman M, Kramer PH, et al (July 2005). "Percutaneous left atrial appendage transcatheter occlusion (PLAATO system) to prevent stroke in high-risk patients with non-rheumatic atrial fibrillation: results from the international multi-center feasibility trials". J. Am. Coll. Cardiol. 46 (1): 9–14. doi:10.1016/j.jacc.2005.03.042. PMID 15992628. 
  9. ^ Bayard Y, Omran H, Kramer P et al (2005). "Worldwide experience of percutaneous left atrial appendage transcatheter occlusion (PLAATO)". J. Neurol. Sci. 238: S70–S70 [abstract].
  10. ^ a b Onalan O, Crystal E (February 2007). "Left atrial appendage exclusion for stroke prevention in patients with nonrheumatic atrial fibrillation". Stroke 38 (2 Suppl): 624–30. doi:10.1161/01.STR.0000250166.06949.95. PMID 17261703. 
  11. ^ Schmidt H, Hammerstingl C, von der Recke G, Hardung D, Omran H (2006). "Long-term follow-up in patients with percutaneous left atrial appendage transcatheter occlusion system (PLAATO): risk of thrombus formation and development of pulmonary venous obstruction after percutaneous left atrial appendage occlusion". J. Am. Coll. Cardiol. 47: 36A.
  12. ^ name=pmid14571497>Meier B, Palacios I, Windecker S, et al (November 2003). "Transcatheter left atrial appendage occlusion with Amplatzer devices to obviate anticoagulation in patients with atrial fibrillation". Catheter Cardiovasc Interv 60 (3): 417–22. doi:10.1002/ccd.10660. PMID 14571497. 
  13. ^ Amplatzer left atrial appendage occlusion: Single center 10-year experience. Nietlispach F, Gloekler S, Krause R, Shakir S, Schmid M, Khattab AA, Wenaweser P, Windecker S, Meier B. Catheter Cardiovasc Interv. 2013 Feb 14. doi: 10.1002/ccd.24872.Epub ahead of print
  14. ^ Yanping Cheng; Jenn McGregor; Robert Sommer; TCT-764 Safety and Biocompatibility of the Coherex WaveCrest™ Left Atrial Appendage Occluder in a 30-Day Canine Study J Am Coll Cardiol. 2012;60(17_S)
  15. ^ Bartus K, Han FT, Bednarek J. Percutaneous Left Atrial Appendage Suture Ligation Using the LARIAT Device in Patients With Atrial Fibrillation: Initial Clinical Experience. J Am Coll Cardiol. 2013 Jul 9;62(2):108-18.
  16. ^ Crystal E, Lamy A, Connolly SJ, et al (January 2003). "Left Atrial Appendage Occlusion Study (LAAOS): a randomized clinical trial of left atrial appendage occlusion during routine coronary artery bypass graft surgery for long-term stroke prevention". Am. Heart J. 145 (1): 174–8. doi:10.1067/mhj.2003.44. PMID 12514671. 
  17. ^ Healey JS, Crystal E, Lamy A, et al (August 2005). "Left Atrial Appendage Occlusion Study (LAAOS): results of a randomized controlled pilot study of left atrial appendage occlusion during coronary bypass surgery in patients at risk for stroke". Am. Heart J. 150 (2): 288–93. doi:10.1016/j.ahj.2004.09.054. PMID 16086933. 
  18. ^ Johnson WD, Ganjoo AK, Stone CD, Srivyas RC, Howard M (June 2000). "The left atrial appendage: our most lethal human attachment! Surgical implications". Eur J Cardiothorac Surg 17 (6): 718–22. doi:10.1016/S1010-7940(00)00419-X. PMID 10856866. 
  19. ^ Blackshear JL, Johnson WD, Odell JA, et al (October 2003). "Thoracoscopic extracardiac obliteration of the left atrial appendage for stroke risk reduction in atrial fibrillation". J. Am. Coll. Cardiol. 42 (7): 1249–52. doi:10.1016/S0735-1097(03)00953-7. PMID 14522490. 
  20. ^ Sick PB, Schuler G, Hauptmann KE, et al (April 2007). "Initial worldwide experience with the WATCHMAN left atrial appendage system for stroke prevention in atrial fibrillation". J. Am. Coll. Cardiol. 49 (13): 1490–5. doi:10.1016/j.jacc.2007.02.035. PMID 17397680. 
  21. ^ Fountain R, Holmes DR, Hodgson PK, Chandrasekaran K, Van Tassel R, Sick P (October 2006). "Potential applicability and utilization of left atrial appendage occlusion devices in patients with atrial fibrillation". Am. Heart J. 152 (4): 720–3. doi:10.1016/j.ahj.2006.05.001. PMID 16996847. 
  22. ^ Zimmerman MB, Blaine EH, Stricker EM (January 1981). "Water intake in hypovolemic sheep: effects of crushing the left atrial appendage". Science 211 (4481): 489–91. doi:10.1126/science.7455689. PMID 7455689. 
  23. ^ Yoshihara F, Nishikimi T, Kosakai Y, et al (August 1998). "Atrial natriuretic peptide secretion and body fluid balance after bilateral atrial appendectomy by the maze procedure". J. Thorac. Cardiovasc. Surg. 116 (2): 213–9. doi:10.1016/S0022-5223(98)70119-9. PMID 9699572. 
  24. ^ Omari BO, Nelson RJ, Robertson JM (August 1991). "Effect of right atrial appendectomy on the release of atrial natriuretic hormone". J. Thorac. Cardiovasc. Surg. 102 (2): 272–9. PMID 1830916.