New Technology: 核磁共振相容節律器 - ”MRI Standard of Care for Pacemaker”)_20130907北區

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New Technology: 核磁共振相容節律器 - ”MRI Standard of Care for Pacemaker”)_20130907北區

  1. 1. MRI Conditional Pacemaker 核磁共振相容節律器 Sep 07, 2013 振興醫院 張鴻猷醫師 2013 Taiwan Heart Rhythm Society – Allied Professional Education Program
  2. 2. MR Conditional Labeling* MR Safe MR Conditional MR Unsafe *ASTM standard F2503: Standard Practice for Marking Medical Devices and Other Items for Safety in the Magnetic Resonance Environment An item that has been demonstrated to pose no known hazards in a specified MRI environment with specified conditions of use.
  3. 3. MRI 基本步驟 •1. 把人放進去MRI裡 •2. 給能量去激發人體內的氫原子 •3. 把能量關掉 •4. 接收氫原子激發後回傳的能量波 •5. 轉換此能量波訊號成為影像
  4. 4. 設備圖 Magnet Gradient Coil RF Coil RF Coil 4T magnet gradient coil (inside) B0
  5. 5. Main Components of a MRI Scanner • Static Magnetic Field Coils • Gradient Magnetic Field Coils • Magnetic shim coils • Radiofrequency Coil • Control computer 1.5 or 3.0 telsa 1 telsa (T) = 10000 gauss 地球磁場 = 0.5 gauss
  6. 6. Transmit Receive RF coil RF coil Main magnet Main magnet GradientShimming Control Computer
  7. 7. 質子 (Proton) •帶正電 •會自旋
  8. 8. The Effect of Irradiation to the Spin System Lower Higher Spin System After Irradiation
  9. 9. MRI 原理 •利用磁場原理,把人體置於強大且均勻的靜磁場 (static magnet) 中,再利用特定的射頻無線電 波脈衝,激發人體組織內的氫原子核 •由於人體內的水分子和脂肪都含有氫原子核,這 些氫原子核本身又具有磁場特性,如同一個小小 的磁鐵 •若使儀器改變體內氫原子核的旋轉排列方向,原 子核就會釋放吸收的能量,能量激發後放出電磁 波信號,再經由電腦分析組合成影像,這就是一 般所看到的 MRI 影像 •由於不同的組織受到刺激後,釋出不同的回波, 因此在影像上便會產生非常良好的對比
  10. 10. MRI 優點 •非侵入性、無傷害的診斷系統,沒有使用 X 光及 放射線物質 •安全、無痛苦,能呈現具體的多方向切面影像 •可以很精細的提供腦部、脊椎、軟組織的狀況 •所測量的不僅是組織的解剖影像,更重要的是組 織的各種功能性影像,具備對各種組織器官功能 性與新陳代謝性障礙的診斷能力 •檢查前病患不需要特別做什麼準備,例如在檢查 前不需要空腹、可以進食
  11. 11. MRI 缺點 •設備費用昂貴,檢查費用較高 •掃描時間需時較長 •對肺部的檢查不優於X射線或CT檢查 •對身體移動非常敏感,若移動易產生偽影,故不 適合急診病患及危急病人,也容易引發禁閉恐懼 症 •心律調節器、金屬性人工心臟瓣膜、各類電子傳 導器、腦動脈瘤手術夾等裝置會受到磁場干擾, 患者不適合 MRI 檢查 •無法鑑別鈣化點
  12. 12. 裝置節律器的病人常需要MRI檢查 It is estimated that 50 to 75% of pacemaker patients will have a medical need for an MRI over the lifetime of their device Average Age of Pacemaker Patient 13% Ages 25-64 86% Age 65+ The Prevalence of Common Comorbidities Increases Rapidly Over Age 65
  13. 13. 慢性病多、需要多專科同時照護 Number of Comorbidities in Pacemaker Patients 85% of all pacemaker patients have one or more comorbidities 15% 0 comorbidities 30% 1 comorbidity 28% 2 comorbidities 27% 3 or more comorbidities Opthalmology Otolaryngology Neurosurgery Neurology Cardiothoracic Surgery Surgical Oncology Nephrology Gynecologic Oncology Urology Rheumatology Oncology Radiation Oncology Interventional Radiology Gastrointestinal Surgery Orthopedic Surgery Vascular Surgery 85%1 1 or more comorbidities 1 Kalin R, Stanton MS. PACE. 2005;28:326-328.
  14. 14. MRI: Three Powerful Fields Static Field Gradient Field RF Field MP – 14
  15. 15. 背景磁力永遠存在
  16. 16. Static Gradient RF Device Interactions Stimulation (UCS) Lead Heating UCS = unintended cardiac stimulation - Inhibitor pacemaker function - Trigger rapid pacing - Deliver inappropriate shocks
  17. 17. Lead Heating Clinical Impact • PCT = Pacing Capture Threshold • PCT is lowest at implant • Healing produces scar • Increased distance increases PCT • Significant heating causes tissue damage • Increased scar volume increases PCT
  18. 18. Stimulation hazard gradient-induced high rate pacing Start of Scan EKG Pulse Ox Canine Test Unintended Stimulation Clinical Impact The MRI scanner is pacing the heart
  19. 19. Device Interactions Clinical Impact Failures can be temporary or permanent MP – 53
  20. 20. Pacemaker System Design Solutions
  21. 21. Device Design Solutions • Minimize ferromagnetic content Unintended cardiac stimulationDevice interactionsForce and Torque • Hybrid-case connection • Hall sensor • Optimize input circuitry
  22. 22. Lead Heating Design Solution • Lead inner conductor coil design mitigates lead heating • 4 filar to 2 filar increases inductance and reduces heating • 5086 provides 3:1 reduction in lead tip heating 0 10 20 30 40 50 60 70 80 90 100 0 5 10 15 20 25 30 35 40 45 50 PercentofMaximum Lead Path 5076 vs. 5086MRI Comparison 5076-52 5086-52
  23. 23. Clinical Confirmation of Safety
  24. 24. Clinical Study Experience (EnRhythm MRI) • Prospective, randomized, multi- center – Implantation: 464 subjects – 41 international centers • 21 Europe, 13 U.S., 6 Canada, 1 Middle East • Enrollment: – February 2007 through July 2008 • Primary End Points: – Consistent Capture Thresholds – Consistent Sensed Amplitudes
  25. 25. MRI Group MRI Scans 9-12 Week Visit Post-MRI Pre-MRI Control Group No MRI 1-Week Post-MRI Visit 1-Month Post-MRI Visit Enrollment 2 Month Visit Implant and Randomization Clinical Visit Schedule 6-Month Post-Implant Visit and Every Six Months Thereafter
  26. 26. Primary Effectiveness Endpoint No measurable difference between MRI and control groups Atrial & Ventricular Capture Threshold: Pre-visit to 1-month post-visit 0 20 40 60 80 -1 -0.5 0 0.5 1 Change in Atrial Threshold (V) %ofPatients MRI (n=165) Control (n=164) 0 20 40 60 80 -1 -0.5 0 0.5 1 Change in Ventricular Threshold (V) %ofPatients MRI (n=190) Control (n=184)
  27. 27. Clinical Confirmed Safety and Effectiveness • Safety demonstrated – No MRI-related complications – No sustained ventricular arrhythmias or asystole • Effectiveness demonstrated – Consistent capture thresholds – Consistent sensed amplitudes
  28. 28. • Complete system: MRI compatible pacemaker with two MRI compatible leads • Implanted for at least 6 weeks • No abandoned leads • Pacing capture threshold ≤ 2.0 V at 0.4 ms • Lead impedance of 200 Ω to 1500 Ω • SureScan programming US Conditions of Use – Cardiology
  29. 29. • 1.5 Tesla Scanner • Gradient field: – Maximum Gradient Slew Rate ≤ 200 T/m/s (per axis) • RF field: Normal Operating Mode – Whole body SAR ≤ 2.0 W/kg – Head SAR < 3.2 W/kg • Patient monitoring US Conditions of Use – Radiology
  30. 30. Patient Care Pathway 1. Pre-Screening and Scheduling 2. Pre-scan 3. Scan 4. Post-Scan
  31. 31. Pre-screening • Ways to ID pacemaker system: 1. Patient ID Card 2. X-Ray 3. Call cardiology 1 PRESCREENING 2 PRE-SCAN 3 SCAN 4 POST SCAN
  32. 32. X-Ray Radiopaque identifies the system via unique radiopaque visible under x-ray 1 PRE- SCREENING 2 PRE-SCAN 3 SCAN 4 POST SCAN 1 Location of the device radiopaque symbol 2 Device radiopaque MRI symbol 3 Lead radiopaque MRI symbol
  33. 33. Programmer print out Programmer Printout Provides confirmation that the system is MR- Conditional, model number and checklist for relevant conditions 1 PRE- SCREENING 2 PRE-SCAN 3 SCAN 4 POST SCAN
  34. 34. SureScan Programming Steps 1 PRE- SCREENING 2 PRE-SCAN 3 SCAN 4 POST SCAN
  35. 35. During the Scan – Monitoring • Patient must be monitored during the MRI scan: – Visual and verbal contact – Pulse oximetry – Blood pressure – Electrocardiography (rate only) • There is no requirement for the monitoring person to be from cardiology. 1 PRE- SCREENING 2 PRE-SCAN 3 SCAN 4 POST SCAN
  36. 36. Post-Scan 1 PRE- SCREENING 2 PRE-SCAN 3 SCAN 4 POST SCAN
  37. 37. Thank you!!

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