Evaluation of hemodialysis arteriovenous fistula before and after surgery: Teaching points

Transcription

1 Evaluation of hemodialysis arteriovenous fistula before and after surgery: Teaching points Poster No.: C-0625 Congress: ECR 2014 Type: Educational Exhibit Authors: L. C. C. Chierighini, P. C. Francolin, M. C. Chammas, G. G. Cerri; Sao Paulo/BR Keywords: Grafts, Fistula, Education and training, Shunts, Diagnostic procedure, Ultrasound-Colour Doppler, Vascular DOI: /ecr2014/C-0625 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 43

2 Learning objectives Demonstrate the normal vascular anatomy of the upper limbs to color Doppler study and the main points to be studied in the pre-operative period for achievement of fistulas for hemodialysis. Demonstrate the main pathologies that may compromise the achievement of an AVF for hemodialysis. Demonstrate the normal anatomy and the standard normal flow of an AVF for hemodialysis, after its realization. Demonstrate the main complications that may lead to the loss of functioning of the AVF after its realization. Recommended protocols for evaluation of an AVF thru the study with color Doppler. Recognition of alternative surgical methods to the AVF with native bed, characterized by the use of synthetic prostheses. Images for this section: Page 2 of 43

3 Fig. 1: B-mode image of normal brachycephalic AVF. Observe the parietal calcified plaques in the brachial artery (ART BRAQ), and anastomosis between the artery and vein (a). Page 3 of 43

4 Fig. 2: Color and pulsed Doppler mapping of the afferent artery in patients with AVF in normal operation, showing the normal pattern of low impedance blood flow in patients with AVF. Page 4 of 43

5 Fig. 3: Color and pulsed Doppler mapping of efferent vein, in a patient with normal functioning AVF, demonstrating the pattern of arterial flow in the veins of patients with AVF. Page 5 of 43

6 Fig. 4: Color and pulsed Doppler in normal efferent vein with AVF. Observe normal turbulent flow in this segment. Page 6 of 43

7 Fig. 5: Color and pulsed Doppler in normal arteriovenous anastomotic. Observe the usual turbulent flow in this segment. Page 7 of 43

8 Background The transplant is the definitive treatment of renal insufficiency, in our days. While waiting for it, the arteriovenous fistula surgery is standard procedure. However, factors such as the local anatomy, technique mistakes and thrombophlebitis may compromise the viability of the fistula as vascular access for hemodialysis. Ultrasound is the main method of diagnostic imaging, because of its low cost, noninvasive, without ionizing radiation associated or iodized contrast. It aims to map the arterial and venous vascular anatomy of the upper limb, evaluating the feasibility of arteriovenous fistulas, their possible complications, maturity and efficiency. It is also sensible for the evaluation of the feasibility of the vascular bed in synthetic graft for hemodialysis. Vascular procedures and their complications represent a major cause of morbidity, hospitalization and cost for patients in hemodialysis. Native arteriovenous fistulas (AVF) are preferable to synthetic arteriovenous grafts (PTFE - Polytetrafluoroethylene) for being associated with lower frequency to thrombosis and infection, as well as a greater longevity. The preoperative physical examination performed by the surgeon is important for setting between AVF and synthetic graft. The preoperative vascular ultrasonographic mapping of upper limb, including nonpalpable and proximal veins, as well as the arterial flow, improve the success rate of the AVF or indicate the selection of the graft as appropriate option. The graft is an option when the vascular anatomy is not appropriate to the positioning of the AVF. Avoid the creation of an AVF in the dominant upper limb. The preoperative diameter criteria used are: all the arteries of 2.0 mm or larger and all the veins, both in the forearm and arm, 2.5 mm or more for the creation of AVF, or veins of 4.0 mm or larger for the creation of the graft. AVF are preferably placed in the wrist or elbow, respectively radial-cephalic and brachialcephalic fistulas. Many fistulas do not mature appropriately for being used in dialysis. Four months is the maximum interval for AVF mature. The early recognition through the ultrasound examination, of problems in the AVF maturation or possible complications that may compromise their viability, offers the opportunity of correction or appropriate treatment. The objective quantitative criteria to assess the maturation of fistulas are: Page 8 of 43

9 - Minimum Diameter of 4 mm (vein) - Flow > 500 ml/min. - Depth of up to 5 mm from the skin Images for this section: Fig. 6: B-mode image demonstrating measurement of the diameter of the normal cephalic vein. Page 9 of 43

10 Fig. 7: Color and pulsed Doppler ultrasonography showing calculation of volume flow in the efferent vein. Page 10 of 43

11 Fig. 8: Color and pulsed Doppler image demonstrating how to perform the calculation of the volume flow. Page 11 of 43

12 Fig. 9: Calculation of systolic peak velocity at the level of the arteriovenous anastomosis with color and pulsed Doppler, for search of stenosis. Page 12 of 43

13 Findings and procedure details The Color Duplex-Doppler ultrasound examination can be accomplished in the preoperative period, to study the best surgical bed available and can be performed in the postoperative control, to identify possible failure factors in the process of AVF maturation. Pre-operative examination: The examination is performed with high frequency linear transducer. Patient seated and the arm to 45 from the body, with appropriate support. The study of the superficial venous system veins can be accomplished with a clipping of the upper limb, respecting the interval of 3 minutes. The exam can also be performed without a clipping, as long as it's applied abundant amount of contact gel and the study is performed without compression of the transducer. We get an overview on B-mode of the upper limb vessels and we do the measures of arteries and veins diameters in the transverse plane. The cephalic and basilic veins diameters are obtained at the wrist level, cubital wrinkle and middle third of the arm. Evaluate the arterial and venous bed patency, with research of thrombosis, thrombophlebitis and arterial stenosis. If there are concentric arterial calcifications, these should be reported because they can harm the anastomosis. The radial and ulnar arteries systolic and diastolic peak speeds are obtained at the wrist level and the brachial artery in the antecubital fossa. Evaluate the palmar arch patency, through compression of the radial artery at the wrist level and visualization of reverse flow distal to the compression. Evaluate the vessels depth and accessory surface venous network. Postoperative examination: The examination is performed with high frequency linear transducer. Patient seated and the arm to 45 from the body, with appropriate support. We get a B-mode overview of the artery feeding the fistula, venous drainage and anastomosis region, including the vessel diameter, both in transverse and longitudinal planes. Page 13 of 43

14 The anteroposterior diameter of the drainage vein is measured in the transverse plane in the distal, middle and proximal portions of the arm or forearm, respectively if fistula is at elbow or wrist. The blood flow is obtained in the middle of the forearm or arm, also depending on if fistula is at wrist or elbow, because stenosis or extremely sinuous drainage veins are rarely seen in this topography, but may limit the flow anywhere in the drainage vein. The main complications found in ultrasonography study after AVF confection includes: - Thrombosis: The thrombosis can be characterized by the presence of echogenic material organized in the lumen veins, with partial or absent flow, depending on the presence of recanalization. Dynamic compression maneuvers are very useful in the evaluation of veins with low speed flow. - Thrombophlebitis: The superficial veins thrombosis can be characterized by the presence of echogenic material organized in lumen of these veins, with partial or absent flow, depending on the presence of recanalization. Dynamic compression maneuvers are very useful in the veins evaluating due to its low speed flow. They are also frequent parietal thickening and caliber reduction, usually translating sequel to previous thrombophlebitis, which shall be described in the final report. - Arterial Stenosis: The arterial stenosis is not frequent in upper limbs in the normal population, when compared with the incidence in the lower limbs. However, chronic renal patients exhibit arterial stenosis in this bed more often than the normal population. We used as a criterion for stenosis the luminal narrowing with Color Doppler mapping, the presence of "Aliasing" at the point of stenosis and an increase of systolic velocity, reaching or exceeding the ratio of 2:1 in relation to the prestenotic bed. - Stenosis at the anastomosis: We used as criteria for arteriovenous anastomosis stenosis, besides the luminal narrowing in B-mode, the increase of systolic velocity, reaching or exceeding the ratio of 3:1 in relation to the pre anastomotic arterial bed. -Stenosis in the efferent vein: The stenosis may result from manipulation (repeated punctures in the same place), partial intraluminal thrombus or narrowing areas in valve sinus. We use as a criteria for stenosis the luminal narrowing at B-mode and Color Doppler mapping, the presence of "Aliasing" at the point of stenosis and an increase of systolic velocity, reaching or exceeding a ratio of 2:1 in relation to the prestenotic bed. Page 14 of 43

15 - Arterial occlusions: the arterial occlusion will be characterized by the absence of detectable Color and Pulsed Doppler mapping. It is important the correct parameters setting of the device (PRF, wall filter, gain and frequency) in order to avoid false positives. - Collections: The collections can be developed by multiple reasons, highlighting hematomas and abscesses in surgical beds. Are particularly feared the infected collections related to the synthetic prostheses, which often evolve with necessity of its withdrawal. They are characterized by the presence of anechogenic or hypoechogenic content, in some situations organized and correlation with clinical data should be performed. - Aneurysms: The vascular dilations can occur in both afferent arteries as in efferent veins. Its determination through the ultrasound is easy, being related to dilated vascular structure, previously displayed at clinical examination. It is important to determine if there is any venous or arterial obstructive process associated. - Steal syndrome: The arteriovenous fistula is a shunt between a high pressure system (arterial) and a low pressure system (venous). Usually the palmar arch compensates circulatory deficiencies of one of the arteries. However, if the palmar arch is incompleted and or the arteriovenous fistula presenting high throughput, it can kidnap the flow originally intended to distal bed, determining ischemic symptoms. This phenomenon can be observed by the inversion of flow direction of the distal artery bed. - Synthetic prostheses (PTFE): Besides the evaluation by B-mode to exclude the possibility off collections, we do studies with color and pulsed Doppler to characterize the patency and exclude synthetic graft stenosis. We use as standard the following parameters: - Flow below 1,300 ml/min. - Stenosis > 50% at B-mode - Systolic peak speed > 400 cm/s - Maturity: The maturity assessment is performed through clinical examination and ultrasonographic analysis, being used as criteria the following parameters: - Minimum Diameter of 4 mm (vein) - Flow > 500 ml/min - Depth of up to 5 mm from the skin Page 15 of 43

16 Images for this section: Fig. 10: B-mode image demonstrating subacute thrombosis of cephalic vein. Page 16 of 43

17 Fig. 11: B-mode image demonstrating the presence of thrombus in the efferent vein of an AVF. Page 17 of 43

18 Fig. 12: B-mode image showing the efferent vein occlusion in AVF (VEIA). Note that the afferent artery (ARTERIA) presents pervious. Page 18 of 43

19 Fig. 13: Color Doppler mapping showing occlusion of the efferent vein in AVF (VEIA). Note that the afferent artery (ART) presents pervious. Page 19 of 43

20 Fig. 14: B-mode image demonstrating intraluminal thrombus in the brachial vein. Note the lack of compressibility (right). Page 20 of 43

21 Fig. 15: B-mode image showing endoluminal organized thrombus in the right subclavian vein. Page 21 of 43

22 Fig. 16: Color and pulsed Doppler mapping demonstrating occlusion of the brachial artery. Page 22 of 43

23 Fig. 17: Color Doppler mapping of occluded radiocephalic AVF, demonstrating thinning and absence of flow in the left cephalic vein (V CEF ESQ). Page 23 of 43

24 Fig. 18: Conventional B-mode ultrasound, of stenosis in efferent vein near the arteriovenous anastomosis, showing area of narrowing well characterized by method (arrow). Page 24 of 43

25 Fig. 19: Color Doppler image of efferent vein stenosis next arteriovenous anastomosis, demonstrating an area of narrowing associated with aliasing at color Doppler. Page 25 of 43

26 Fig. 20: Color and pulsed Doppler image near efferent vein stenosis in arteriovenous anastomosis, showing area of narrowing with the presence of color Doppler aliasing. Note that the peak systolic velocity in the stenosis exceeds the ratio of 3:1 with respect to speed calculated in arteriovenous anastomosis. Page 26 of 43

27 Fig. 21: B-mode image showing stenosis of efferent vein in AVF. Page 27 of 43

28 Fig. 22: B-mode image showing stenosis of efferent vein in AVF. Page 28 of 43

29 Fig. 23: B-mode image showing stenosis of efferent vein in AVF. Page 29 of 43

30 Fig. 24: Color and pulsed Doppler mapping demonstrating efferent vein stenosis in AVF. Fig. 25: B-mode image demonstrating efferent vein stenosis, in transverse (left) and longitudinal scans (right). Page 30 of 43

31 Fig. 26: Color and pulsed Doppler demonstrating elevation of peak systolic velocities at the point of efferent vein stenosis. Page 31 of 43

32 Fig. 27: Color and pulsed Doppler demonstrating elevation of peak systolic velocities at the point of efferent vein stenosis (right, "ESTENOSE"). Observe the low speed prestenotic (left, "FLUXO PRE"). Page 32 of 43

33 Fig. 28: B-mode image of AVF, showing dilatation of the cephalic vein at the level of the arteriovenous anastomosis (VEIA). Page 33 of 43

34 Fig. 29: Doppler amplitude mapping of AVF, demonstrating dilatation of the cephalic vein at the level of the arteriovenous anastomosis (VEIA). Page 34 of 43

35 Fig. 30: Color Doppler mapping showing signs of "kidnapping" in the radial artery. Note that the proximal arterial segment encoding presents in red, and the distal artery anastomosis of AVF presents encoding blue, featuring inversion of its direction of flow. Page 35 of 43

36 Fig. 33: B-mode image demonstrating a synthetic PTFE prosthesis, used for making hemodialysis graft. Page 36 of 43

37 Fig. 34: B-mode image showing the proximal anastomosis of a fistula for hemodialysis, performed with use of synthetic prosthesis. Page 37 of 43

38 Fig. 35: B-mode image of distal anastomosis of PTFE graft without detectable collections. Page 38 of 43

39 Fig. 36: Color and pulsed Doppler demonstrating the normal flow patterns of a patent fistula for hemodialysis, performed with use of synthetic prosthesis. Page 39 of 43

40 Fig. 37: Mapping with color Doppler demonstrating proximal anastomosis of a patent fistula for hemodialysis, performed with use of synthetic prosthesis. Page 40 of 43

41 Fig. 38: Mapping with color and pulsed Doppler demonstrating occlusion in a fistula for hemodialysis, performed with use of synthetic prosthesis. Page 41 of 43

42 Fig. 39: B-mode image of extensive hypoechoic collection in right arm, related to prosthetic PTFE (left). Observe the patent anastomosis of prosthesis with color Doppler mapping, characterizing the extent of the collection until this topography (right). Fig. 40: B-mode image demonstrating intraluminal thrombus in cephalic vein (left), associated with thickening and increased echogenicity of the superficial planes, translating local inflammatory process (thrombophlebitis). Compare with the normal appearance of the subcutaneous tissue of the contralateral limb (right). Page 42 of 43

43 Conclusion The Color Doppler ultrasound is an excellent noninvasive method to analyze the feasibility of arteriovenous fistulas and their possible complications. It is also an excellent method of preoperative evaluation allowing the surgeon an arterial and venous system global vision, making possible to establish the best place for realization of arteriovenous fistula for hemodialysis. Personal information References Robbin M.L., Chamberlain N.E., Lockhart M.E., Gallichio M.H., Young C.Y., Deierhoi M.H., Allon M. Hemodialysis Arteriovenous Fistula Maturity: US evaluation /radiol Radiology 2002; 225: Wiese P., Nonnast-Daniel B. Colour Doppler ultrasound in dialysis access. Nephrol Dial Transplant (2004) 19: Singh P., Robbin M., Lockhart M.E., MD, Allon M. Clinically ImmatureArteriovenous HemodialysisFistulas: Effect of US on Salvage. Radiology 2008; 246: Robbin M.L., Gallichio M.H., Deierhoi M.H., Young C.Y., Weber T.M., Allon M. US Vascular Mapping before Hemodialysis Access Placement. Radiology 2000; 217: Pitta GBB, Castro AA, Burihan E, editores. Angiologia e cirurgia vascular: guia ilustrado.página 2 de 10. Maceió: NCISAL/ECMAL & LAVA; Dumars MC, Thompson WE, Bluth EI. et al. Management of suspected hemodialysis graft dysfunction: usefulness of diagnostic US. Radiology 2002; 222: Page 43 of 43