388 Practical Handbook of Advanced Interventional Cardiology patients with complex coronary anatomy a chance to undergo percutaneous revascularization rather than bypass surgery. REFERENCES 1. Reisman M, Rivera L, McDaniel M et al. Absence of recoil following percutaneous coronary rotational ablation: Analysis by quantitative coronary angiography. Eur Heart J 1992; 13 : 425. 2. Reisman M. Guide to Rotational Atherectomy. Physicians’ Press, 1998. 3. Kaplan BM, Safi an RD, Mojares JJ et al. Optimal burr and adjunctive balloon sizing reduces the need for target artery revascularization after coronary mechanical rotational ather- ectomy. Am J Cardiol 1996; 78(11): 1224–9. 4. Safi an RD, Freed M, Reddy V et al. Do excimer laser an- gioplasty and rotational atherectomy facilitate balloon angio- plasty? Implications for lesion-specifi c coronary intervention. J Am Coll Cardiol 1996; 27(3): 552–9. 5. Casterella P, Terstein P. Rotational coronary atherectomy. In: Grech ED, Ramsdale DR, eds. Practical Interventional Cardiology. Martin Dunitz, 1997. 6. Stuver TP, Ling FS. The “furrowing effect”: Guidewire-in- duced “directional” lesion ablation in rotational atherectomy of angulated coronary artery lesions. Cathet Cardiovasc Di- agn 1996; 39: 385–95. 7. Reisman M, Harms V. Guidewire bias: Potential source of complications with rotational atherectomy. Cathet Cardiovasc Diagn 1996; (Suppl 3): 64–8. 8. Bowling LS, Guarneri E, Schatz RA, Teirstein PS. High- speed rotational atherectomy of tortuous coronary arteries with guidewire-associated pseudostenosis. Cathet Cardio- vasc Diagn 1996; (Suppl 3): 82–84. 9. King SB, Douglas J. Rotational coronary ablation. In: King SB, Douglas J, eds. Atlas of Heart Disease, Interventional Cardiology. Mosby, 1997. 10. Cohen BM, Weber VJ, Blum RR et al. Cocktail Attenua- tion of Rotational Ablation Flow Effects (CARAFE) pilot study. Cathet Cardiovasc Diagn 1996; (Suppl 3): 69–72. 11. Sharma SK, Dangas G, Mehran R et al. Risk factors for the development of slow fl ow during rotational coronary atherec- tomy. Am J Cardiol 1997; 80(2): 219–222. 12. Gregorini L, Marco J, Fajadet J et al. Ticlopidine and as- pirin pretreatment reduces coagulation and platelet activation during coronary dilation procedures. J Am Coll Cardiol 1997; 29(l): 13–20. 13. O’Murchu B, Foremean RD, Shaw RE et al. Role of IABP counterpulsation in high-risk coronary atherectomy. J Am Coll Cardiol 1995; 26(5): 1270–5. Rotational Atherectomy 389 14. Piana RN, Paik GY, Mosucci M et al. Incidence and treat- ment of no-refl ow after percutaneous coronary intervention. Circulation 1994; 89: 2514–18. 15. Rawitscher D, Levin TN, Cohen L, Feldman T. Rapid reversal of no-refl ow using abciximab after coronary device intervention. Cathet Cardiovasc Diagn 1997; 42: 187–90. 16. Cohen BM, Weber VJ, Reisman M, Casale A, Dorros G. Coronary perforation complicating rotational ablation: The US multicenter experience. Cathet Cardiovasc Diagn 1996; (Suppl 3): 55–59. 17. Foster-Smith K, Garratt KN, Holmes DR Jr. Guide tran- section during rotational coronary atherectomy due to guide catheter dislodgment and wire kinking. Cathet Cardiovasc Diagn 1995; 35: 224–7. 18. Feldman T. Rotational ablation of stent metal compo- nents: The intersection between coronary intervention and auto body repair. Cathet Cardiovasc Interv 2001; 52: 212–13. 19. Grise M, Yeager M, Terstein P. A case of an entrapped rotational atherectomy burr. Cathet Cardiovasc Interv 2002; 57: 31–3. 391 *Basic; **Advanced; ***Rare, exotic, or investigational. From: Nguyen T, Hu D, Saito S, Grines C, Palacios I (eds), Practical Handbook of Advanced Interventional Cardiology, 2nd edn. © 2003 Futura, an imprint of Blackwell Publishing. Chapter 20 Intravascular Ultrasound Guy Weigold, Neil J Weissman Introduction Angiography versus IVUS Techniques of IVUS Aneurysms: true, false, or misdiagnosis? Intravascular ultrasound guided interventions New advances in IVUS utilization Conclusion INTRODUCTION Intravascular ultrasound (IVUS) is an exciting technology that allows in vivo visualization of vascular anatomy by using a miniature transducer at the end of a fl exible catheter. The catheter is placed into the coronary artery by standard retro- grade catheterization techniques. Because of the high quality cross-sectional images of the atherosclerotic plaque and sur- rounding vascular structures, IVUS is now clinically used to delineate plaque morphology and distribution, and to provide a rationale for guiding transcatheter coronary interventions. 1 Furthermore, IVUS technology has advanced our knowledge of atherogenesis, vascular remodeling, and mechanisms as- sociated with coronary interventions and restenosis. ANGIOGRAPHY VERSUS IVUS IVUS provides a cross-sectional view of all layers of the coronary artery: the intima, media and adventitia. Working from the inside of the blood vessel out, the fi rst layer en- countered, adjacent to the lumen, is the intima. The intima is 392 Practical Handbook of Advanced Interventional Cardiology normally 1–2 layers of cells thick but can greatly enlarge with the deposition of atherosclerotic plaque. The intima is imme- diately surrounded by the media, which is predominantly a layer of homogenous smooth muscle cells providing vascular tone to the artery. The adventitia surrounds the media and is composed of multiple bands of fi brous connective tissue providing additional external support for the vessel. The cross-sectional images of the vessel provided by IVUS pre- c i se l y ch a r ac t er i ze t he ex te n t a n d lo c a ti o n of p l aq u e w i t hi n th e artery (Figure 20-1). As demonstrated by the image in Figure 20-1, precise determination of plaque burden, morphology, and distribution of plaques is possible through IVUS. 2,3 The most notable dif- ference between angiography and ultrasound measurement is the extensive amount of plaque seen by ultrasound mea- surement that is not detected by angiography. Angiography displays the luminal contour which allows measurements of only the luminal diameter, typically in two or three orthogonal views. Detection of the presence of plaque is then assessed by comparing the degree of narrowing with that of a segment that is not “narrowed,” assuming that this segment is free of atherosclerosis. Unfortunately, the reference segment is often found to be diseased when it is assessed by IVUS measurement, with up to a third of its cross-sectional area fi lled with plaque. As a result, plaque burden is often underes- timated by angiography and the degree of underestimation is substantial for diffusely diseased vessels. 4 The tomographic view of IVUS (with 180 potential diameters) provides the true minimal and maximal luminal diameters together with mea- surements of cross-sectional area. More importantly, IVUS allows visualization of the arterial (external elastic lamina) area as a reference of the size the artery would be if it were devoid of plaque. IVUS provides greater insight into the composition of ath- erosclerotic plaques than angiography. Denser atheroscle- rotic material, such as calcium, will refl ect more ultrasound Atherosclerotic Plaque IVUS Cathet Lumen Figure 20-1: Cross-sectional image of the artery with the three layers and the extent, location of the plaque. Intravascular Ultrasound 393 and appear very bright. 5 Since calcium is extremely dense, very little ultrasound penetrates to deeper tissues, producing an acoustic shadow beyond the very bright calcium deposit (Figure 20-2). Although IVUS displays a cross-sectional image of the artery, it also provides location information within the coronary artery through the use of perivascular anatomic landmarks. Perivascular structures, such as the pericardium, myocardium and cardiac veins, have a characteristic appear- ance. Combining this information with the branching patterns of the arteries produces information for both axial position and tomographic orientation within the artery. For instance, identifying the pericardium from within the LAD provides the reference for anterior orientation, the diagonal branches for leftward orientation and for “downward” or posterior orienta- tion, and septal branches. Pericardium appears as a bright, relatively thick structure. Typically, a small amount of peri- cardial fl uid is enclosed, thereby providing a strong acoustic interface between itself and the pericardium. This enhances the IVUS appearance of pericardial refl ections. 6 TECHNIQUES OF IVUS The risks are minimal, with very low reported complica- tion rates, especially with the progressive miniaturization of transducers and IVUS catheters. The commonly used catheter is 3F, introduced through a guiding catheter over a standard intracoronary wire, imaging with a 40 MHz trans- ducer. Most vessels can be imaged, but the diffusely severely Calcified Lesion Figure 20-2: C a l ci fi e d l e s i on w i t h a c o u st i c s ha d o w c a u s ed b y minimal penetration of ultrasound to deeper tissues beyond the dense calcium deposit. 394 Practical Handbook of Advanced Interventional Cardiology diseased vessel remains a challenge, and an IVUS catheter may simply not pass through such a vessel. After anticoagulation and predilation with intracoronary nitroglycerin (150 –200 µg), the IVUS c atheter is advanced as far down the artery as anatomy and equipment will allow. At this point, motorized pullback withdraws the catheter 0.5 mm per second. Standardization of this pullback is essential for “mapping” the coronary artery. As the catheter is withdrawn, side branches and perivascular landmarks identify the loca- tion of the image being viewed. Longitudinal reconstructions are also useful for vessel mapping, which becomes important when selecting stent or radiation source length. It is important to complete this pullback all the way back to the tip of the guid- ing catheter. Vessel and lumen sizing during on-line IVUS analysis is used to assess lesion severity, select balloon/stent diam- eters for intervention and assess effi cacy of the intervention. Physiologic studies have shown that the minimum lumen area (MLA) of a lesion predicts coronary fl ow reserve, fractional fl ow reserve, and perfusion scan results. 7–9 In general, MLAs (in proximal major epicardial arteries) less than 4.0 mm 2 are considered fl ow-limiting, though considerations of distance from the vessel ostium and size of a patient’s vessels in gen- eral should be considered. In determining stent and balloon size, assessment of the references is necessary. By defi nition, the proximal or distal reference site is that with the largest lumen proximal or distal to a stenosis but within the same segment, usually located within 10 mm of the stenosis with no major intervening branches. 10 IVUS often reveals more plaque than anticipated, and these reference sites may or may not be the sites with the least amount of plaque. The goal of the intervention, from the IVUS standpoint, is to obtain the best “match” between the reference lumen area and the fi nal cross-sectional area of the stented segment. This ensures smooth “infl ow” into and “out- fl ow” out of the stented segment. In addition to equipment sizing, IVUS can also be used to choose type of intervention and to alert operators to the poten- tial for complications prior to proceeding with angioplasty. For example, fi nding signifi cant concentric calcifi cation at a lesion site may prompt use of rotational atherectomy to “break up” calcium prior to attempting vessel dilation, and this “plaque modifi cation” of the vessel may help avoid what would other- wise become a dissection when the vessel is dilated. Since the development of balloon angioplasty and, more recently, cutting balloons, it has become clear that the actual effect of the balloon is much more complex, involving tearing and displacement of the plaque and stretching of the arterial wall. 1 These factors vary from lesion to lesion and are unpredictable from angiographic appearance alone. 1 IVUS allows the visualization of these small splits, tears, fi ssures Intravascular Ultrasound 395 or dissections that occur spontaneously or after a coronary intervention (Figure 20-3). In addition to assessing plaque distribution, IVUS also allows for visualization of vessel injuries, such as intramural hematomas. Intramural hematomas are extravasations of blood localized in the arterial media. These can result from intimal fracture of an atherosclerotic plaque or bruising due to transcatheter interventions. Since intramural hematomas occur in the vessel wall, they may not be detectable through angiography. In one study, 30% of hematomas were not visu- alized by angiography. IVUS, on the other hand, allows visual- ization of all arterial layers, which greatly facilitates detection of intramural hematomas (Figure 20-4). Dissection Dissection Figure 20-3: The entry of the dissections appears at 6 o’clock at the shoulder (junction) between a calcifi ed plaque and the normal intima. Figure 20-4: An intramural hematoma expands from 3 o’clock to 10 o’clock while a calcifi ed plaque with an acoustic shadow covers the rest of the arterial wall. Calcifi ed plaque Calcifi ed HematomaHematoma 396 Practical Handbook of Advanced Interventional Cardiology Intr amu ral h em atom a pro du c ti on i s as so ci ated w it h c l in i- cal vascular outcomes. Therefore it is important to be aware of t h i s c o m p l i c a t i o n o f P T C A i f i t o c c u r s . I V U S c a n r e l i a b l y i d e n t i f y it. In a study of 905 patients in native coronary arteries, 11 IVUS detected 72 hematomas out of 1025 PTCAs (7% of PTCAs), occurring in 68 (7.5%) of patients. Surprising, only a minority (18%) of hematomas occurred at the site of the lesion itself, while the remainder occurred in either the proximal (26 of 72) or distal (33 of 72) reference segment, which is defi ned as the segment with the largest lumen within 10 mm of the lesion. One-month target vessel revascularization was signifi cantly higher in the patients who developed an intramural hematoma (6.3%) versus those who did not (1.9%, P=0.046). ANEURYSMS: TRUE, FALSE, OR MISDIAGNOSIS? IVUS can clarify the morphology of coronary abnor- malities which appear to be aneurysms on angiography. What appear to be aneurysmal dilatations or “outpouchings” of a coronary vessel on angiography may actually be complex plaques, or even normal arteries adjacent to stenosed seg- ments. In an intracoronary ultrasound study of 77 coronary aneurysms diagnosed by angiography, 12 21 (27%) were true aneurysms (Figure 20-5) with an intact, three-layered ves- sel wall, but 41 (53%) were actually short normal segments fl anked by stenotic portions. Three (4%) were actually pseu- doaneurysms (Figure 20-6), in which vessel perforation had resulted in a disrupted vessel wall, leaving only a residual out- ward “bulging” monolayer. Twelve (16%) were not aneurysms at all, but complex plaques. All of the pseudoaneurysms appeared as “saccular” types on angiography, while most (80%) of the normal seg- ments fl anked by stenoses had a “fusiform” appearance. True aneurysms and complex plaques appeared as either form equally, thus the angiographic shape of the aneurysm could not predict the true lesion anatomy. Figure 20-5: True aneurysm has intact, three-layered wall as seen from 1 o’clock to 6 o’clock position. Intravascular Ultrasound 397 In summary, what appear to be coronary aneurysms on angiography may in many cases actually be pseudoaneu- rysms or not aneurysms at all. This can only be distinguished by IVUS analysis. Therapeutic and interventional decisions are likely to be heavily infl uenced by IVUS fi ndings in these scenarios. INTRAVASCULAR ULTRASOUND GUIDED INTERVENTIONS IVUS can provide valuable insight prior to coronary inter- vention. Many lesions of various etiologies angiographically appear as areas of haziness. These hazy angiographic sites are often irregular plaques, distorted lumens, napkin-ring lesions, thrombi, or dissections. Also, because IVUS allows visualization beyond the lumen, vascular remodeling assess- ment or intervention planning in a remodeled vessel can be accomplished. Glagov et al. 13 have shown that coronary arter- ies will enlarge to accommodate focal deposition of plaque in an attempt to maintain luminal integrity. Since successful compensatory enlargement will preserve the luminal contour, there will be no angiographic stenosis despite the deposition of signifi cant plaque. IVUS measurement can detect expan- sion of vessels (enlargements of media-to-media diameter) and the focal plaque burden, and allow the interventionalist to size the device appropriately. Since many stents are diffi cult to visualize by angiog- raphy, complete assessment of adequate deployment is dependent upon IVUS. Angiographic assessment of stent Figure 20-6: The pseudoaneurysm has only one layer in its wall which is the adventitia. The media was ruptured. Pseudoaneurysm The characteristic finding is a “br e the media. Compare to true aneur y 23-5 ) . The characteristic fi nding is a “break” in the media. Compare to true aneurysm (Fig. 20-5) [...]... anticipated short- and long-term *Basic; * *Advanced; ***Rare, exotic, or investigational From: Nguyen T, Hu D, Saito S, Grines C, Palacios I (eds), Practical Handbook of Advanced Interventional Cardiology, 2nd edn © 2003 Futura, an imprint of Blackwell Publishing 4 07 408 Practical Handbook of Advanced Interventional Cardiology clinical benefits are the major determinants of the role of catheter techniques... six-month follow-up of 56 patients receiving paclitaxel-coated stents in Asia, IH burden amounted to 13 to 18 mm3, compared to 31 mm3 in patients receiving bare metal stents.26 This represented 13% to 17% 402 Practical Handbook of Advanced Interventional Cardiology of the stent volume, compared to 30% in the control group Minimum lumen area (the cross-sectional area of the “worst” part of the stent)... via the left common femoral artery, and balloon angioplasty of both the right and left common iliac arteries is performed (Figure 2 1-1 0); “kissing” stents are positioned (Figure 2 1-1 1) 422 Practical Handbook of Advanced Interventional Cardiology Figure 2 1-6 Figure 2 1 -7 Percutaneous Ilio-femoral Revascularizations 423 Figure 2 1-8 Figure 2 1-9 ... two-dimensional images to provide a three-dimensional reconstruction of the coronary and a longitudinal view, Normal Distal Internal Carotid Calcified Carotid Lesion Figure 2 0-8 : Cross-sectional images of the distal internal carotid artery with minimal plaque and the origin of the internal carotid artery with calcified plaque 400 Practical Handbook of Advanced Interventional Cardiology Figure 2 0-9 :... treating a stenosis versus an occlusion (>90% vs 75 –85%, respectively) Additionally, close attention must be paid to the number of patent infrapopliteal vessels as patients with poor run-off (0–1 vessels) consistently show poorer longterm outcomes than those with 2–3 vessel run-off.1 410 Practical Handbook of Advanced Interventional Cardiology Table 2 1-2 The TASC recommendations for femoropopliteal... after implantation of sirolimus-eluting stents in human coronary arteries Circulation 2003; 1 07: 381–83 25 Serruys PW, Degertekin M, Tanabe K et al Intravascular ultrasound findings in the multicenter, randomized, doubleblind RAVEL (Randomized study with the sirolimus-elucint Velocity balloon-expandable stent in the treatment of patients 406 Practical Handbook of Advanced Interventional Cardiology with... Glidewire (Wholey Wire or Magic Cross Wire) 0.035" Soft and Extra-Stiff hydrophilic J and angled wires (Glidewire – MediTech) 0.018" hydrophilic glidewire (V-18 Wire – Medi-Tech) 5F hydrophilic end-hole catheters (Glide-Cath – Medi-Tech) 4F NYL Exchange Catheter (Medi-Tech) cally (DSA is best) to determine the occlusion length, extent of calcification, takeoff of collateral vessels, vessel tortuosity, and... Advanced Interventional Cardiology Figure 2 1-3 Figure 2 1-4 Percutaneous Ilio-femoral Revascularizations 421 Figure 2 1-5 placed in the hub of the sheath Using a vascular clamp, the external portion of the vascular sheath with the glidewire within the sheath is clamped and the wire is externalized as the vascular sheath with the attached wire is pulled through the right groin site (Figure 2 1-6 ) 7 A 7F sheath... hypothesized that the radiation dose fall-off at the edges of the stent might be causing this hyperproliferation (Figure 2 0-1 0) Preventing restenosis: Drug-eluting stents: IVUS has played a key role in the evaluation of early and long-term effects of drug-coated stents IVUS is now considered the gold standard for assessing growth and severity of intimal hyperplasia The drug-eluting stents (DES) have performed... Intravascular Imaging 19 97; 1: 73 –9 15 Russo RJ, Nicosia A, Teirstein PS for AVID Investigators Angiography versus intravascular ultrasound-directed stent placement [abstract] J Am Coll Cardiol 19 97; (suppl): 70 7–14 16 Goldberg SL, Colombo A, Nakamura S et al Benefit of intracoronary ultrasound in the deployment of Palmaz-Schatz stents J Am Coll Cardiol 1994; 24: 996–1003 17 Nakamura S, Colombo A, Gaglione . randomized, double- blind RAVEL (Randomized study with the sirolimus-elucint Velocity balloon-expandable stent in the treatment of patients 406 Practical Handbook of Advanced Interventional Cardiology with. study of 905 patients in native coronary arteries, 11 IVUS detected 72 hematomas out of 1025 PTCAs (7% of PTCAs), occurring in 68 (7. 5%) of patients. Surprising, only a minority (18%) of hematomas. stenosed seg- ments. In an intracoronary ultrasound study of 77 coronary aneurysms diagnosed by angiography, 12 21 ( 27% ) were true aneurysms (Figure 2 0-5 ) with an intact, three-layered ves- sel