Angiography, angioscopy, and ultrasound imaging before and after percutaneous balloon angioplasty We report two patients undergoing peripheral percutaneous transluminal angioplasty in whom angiography, angioscopy, and ultrasound imaging were performed before and after balloon angioplasty. The first case with smooth atheroma diagnosed by angiography was found to have unrecognized partially occlusive thrombus by angioscopy. After angioplasty, an lntimal tear was identified by angioscopy and ultrasound but it was not seen by angiography. The intravascular ultrasound image showed the tear to extend to the adventitia. In the second case, an apparently smooth intimal surface as imaged by angiography was found by angioscopy and ultrasound to have extensive damage, including subintimal hemorrhage, intimal flaps, and arterial dissection at the angioplasty site. These data suggest that the type of information derived from the three imaging techniques is quite different, and that each may have a specific role in intravascular diagnosis. (AM HEART J lggO;120:1088.)
Robert J. Siegel, MD, Jang-Seong Chae, MD, James S. Forrester, MD, and Carlos E. Ruiz, MD. Los Angeles, Calif.
Angiography defines the contour of the blood vessel wall but provides only inferential information about abnormalities of the blood vessel surface and wa1l.l Although intravascular angioscopy and ultrasound, which image the vessel surface and wall directly, could supplement the diagnostic information provided by angiography, there is no report about the use of these techniques in combination. In this communication we report our experience in our first two patients in whom we combined the use of angiography, angioscopy, and ultrasonic imaging before and after percutaneous peripheral transluminal angioplasty (PTA). The cases illustrate important differences in the information obtained by each technique, and suggest that both an insight into the pathogenesis of vascular syndromes and an alteration of operator behavior during intervention may result from the use of intravascular imaging technologies. METHODSANDRESULTS Case No. 1. This patient wasa 72-year-old man with a history of SO-yardclaudication. On physical examination, the right pedal pulsewasnot palpable. After local lidocaine
From Heart
the Divisions of Cardiology, Cedars-Sinai Medical Institute, The Hospital of The Good Samaritan.
Received Reprint Beverly 411123427
1086
for publication requests: Robert Blvd., Cardiology
April
16. 1990;
d. Siegel, Room
accepted
June
MD, Cedars-Sinai 5314, Los Angeles,
Center,
and The
1, 1990.
Medical Center, CA 90048-0750.
8700
analgesia,an 8F arterial sheath wasplaced in an antegrade direction in the ipsilateral femoral artery by percutaneous catheterization. Angiography wasperformed with Hexabrix contrast medium (Mallinckrodt Medical, St. Louis, MO.). Angioscopy was performed with a 1 mm angioscope,light source,and an occlusionballoon (Baxter Healthcare Corp., EdwardsDivision, Santa Ana, Calif.). A pressurizedsystem was used to flush crystalloid solution to obtain a clear viewing field. Subsequently, an SF 20 MHz ultrasound imaging catheter (Cardiovascular Imaging Systems, Sunnyvale, Calif.) was inserted into the vesseland was passed under fluoroscopic guidanceto the distal tibia1 artery. No flushing wasrequired for imaging.Ultrasound imagingwas performed during antegrade passageand pullback of the catheter. Angioscopic and ultrasonic imageswere viewed on a high resolution monitor (Sony Medical Electronics, Park Ridge, N.J.) and wererecorded on l/2-inch videotape. After the baselineimaging with angiography, angioscopy, and ultrasound, balloon angioplasty wasperformed on the stenotic segments.Subsequently, all three imaging methods were repeated. Fig. 1, A, C, E, and G demonstrate the angiographic,angioscopic,and ultrasonographic imagesrecorded prior to angioplasty. By angiography there is a smooth 4 cm long narrowing in the posterior tibia1 artery (Fig. 1, A). This lesion was classifiedas a stable atheroma causinga 75% diameter stenosis. In contrast, angioscopy of this site showeda raisedred massthat wasclassifiedasa thrombus (Fig. 1, C). Based on this image, the masswas extracted from the vessel by aspiration. Subsequent pathologic examination showedit to be a thrombus. The remainder of the vesselhad a yellow-white surfacewith smoothelevated
Volume
120
Number
5
Imaging
techniques
after PTA
1087
Fig. 1. A, Baselineangiogramof posterior tibia1 artery. Arrows denote smooth4 cm long stenosis.6, Angiogram after percutaneousballoon angioplasty reveals a smooth lumen at the angioplasty sites (arrows). C, Angioscopy identifies a red smooth intralumenal mass(arrows) that wasseenand removed prior to ultrasound imaging and angioplasty. D, Angioscopy following angioplasty revealsintimal tear, identified by arrows, not evident by angiography. E, Baselineultrasound imageat the site of the proximal arrow on angiogram (panel B) reveals a narrowed lumen with thickened walls, consistent with atherosclerotic plaque. F, After angioplasty, ultrasound demonstratesa tear and separationof the arterial plaque down to the level of the adventitia. G, Baselineultrasound, at site of distal arrow on angiogram(B) revealsa narrowed lumen with increased echodensity and acoustic shadowing, suggestingcalcification. H, Following angioplasty, fragmentation of the plaque is evident (arrows).
lesions of various sizes, which were classified as stable atheroma. After aspiration of the thrombus, intravascular ultrasound imaging wasperformed. The vesselsurfacewas smooth, and the lumen wasdiffusely narrowed, ultrasound
also demonstrated increasedwall thickness at the site of the raised lesions.Basedon these findings, the vesselwas classifiedas exhibiting diffuse stable atherosclerotic disease(Fig. 1, E). The luminal areawasmeasuredas8.3 mm2
1990
1088
Siegel et al.
in the nondiseasedportion of the vessel,and as2.2 mm2at the most severe stenosis.In addition, we noted increased echo density at the stenotic site, suggestiveof calcification (Fig. 1, G). Theselatter data combined with decreasedarterial pulsation were interpreted as suggestingthat high inflation pressuresmight be required during dilatation. Angioplasty was then performed with a 2.5 mm Meditech (Medi-tech Inc., Watertown, Mass.) balloon catheter using manual inflation for 2 minutes with a 10 cm3syringe containing Hexabrix contrast material. Fig. 1, B, D, F, and H show the angiographic, angioscopic,and ultrasonographic imagesfollowing balloon angioplasty. Angiography demonstrateda 25% residualstenosisat the angioplasty site (Fig. 1,B). The vesselsurfaceappears smooth, and there is no evidence of vascular injury or dissection.The angioscopicimage revealed two linear tears on oppositearterial walls that extended from the angioplasty site to the distal portion of the vessel(Fig. 1, D). There is focal disruption of the intimal surface and subintimal hemorrhage. The intravascular ultrasound image alsodocumentedtearing of the arterial plaque at the same two sites (Fig. 1, F). In addition, the depth and extent of the tear were revealed. The depth reachesthe arterial adventitia, and it extends from the mid to the distal segment of the vessel (Fig. 1, H). The angiographic impressionof increasedluminal diameter was confirmed by direct measurement: the lumen area increasedfrom 8.2 to 8.9 mm2 proximally, and from 2.3 to 2.9 mm2in the distal arterial segment. CaseNo. 2. This patient wasa 75-year-old man with a 5-year history of intermittent claudication, who presented with resting right calf pain. On physical examination, the right popliteal and distal arteries were not palpable. The right lower extremity wascooler than the left but without evidence of ulceration. Angiography, angioscopy, and ultrasound were performed as described in caseNo. 1 and again after intervention. In case No. 2, however, a stiff 0.35-inch guide wire wasusedto crossthe totally occluded segmentprior to balloon angioplasty. The superficial femoral artery wasdilated with a 4 mm Meditech (Medi-tech Inc.) peripheral angioplasty balloon usingmanual inflation for 5 minutes with a 10 cm3 syringe filled with Hexabrix contrast material. Fig. 2, A, C, and E showthe vascular imagesprior to angioplasty. Proximal to the complete occlusion, both the angiographicand angioscopicimagesshowed raised, smooth plaquesand the ultrasound imagedemonstrated a diffusely thickened arterial wall with a smooth lumen. Thus all three modalities gave information consistent with stable atheroma proximal to the total occlusion. Fig. 2,B, D, and F showthe angioplasty site following the procedure. Angiography demonstrated a smooth, residual lumen with antegradeflow to the distal extremity (Fig. 2, B). The residual diameter stenosiswas 65% by caliper measurement.In contrast, angioscopydemonstrated a severely disrupted intimal surface. There were intimal flaps and a region in which the arterial plaque appeared fractured (Fig. 2, D). By ultrasound, an echolucent zone was localized within the plaque. This zone extends 3 cm down the vesseland then reentersthe arterial lumen. This image was classifiedas disrupted atheroma with an arterial dis-
American
November Heart Journal
section (Fig. 2, F). The residual luminal area at the angioplasty site was 5.2 mm2. DISCUSSION
Our case studies demonstrate striking differences in diagnostic conclusions derived from three intravascular imaging techniques. Prior to PTA in case No. 1, an angiographic image classified as a smooth atheroma was found to be a partially occlusive thrombus by angioscopy. After PTA in case No. 2, the intimal surface considered smooth by angiography was found by angioscopy and ultrasound to have evidence of extensive intimal damage, including subintimal hemorrhage, intimal flaps, and dissection at the angioplasty site. Our results are part of an emerging body of evidence that angiographic analysis of the vessel after angioplasty does not reveal the extent of vascular damage. In a postmortem study of 26 patients who died after coronary angioplasty, Potkin and Roberts2 found that 98% of angioplasty sites had intimal disruption. Uchida et al3 found that of 10 sites exhibiting intimal hemorrhage and disruption by percutaneous angioscopy after PTCA, seven were read as normal by angiography. There have also been several comparisons of angiography and angioscopy. Johnson et a1.4 found subintimal dissection 26 times by angioscopy, whereas cineangiography did not demonstrate even one of the flaps, and thrombus was present in 30 angioscopic images but was detected by angiography in only 11. Van Stiegmann et al5 found angioscopic endovascular abnormalities undetected by angiography in 26% of patients. Angioscopy revealed free-floating clots, membrane-like obstructions, and atherosclerotic debris undetected by angiography. These data support the conclusion that unique and important information about the blood vessel may be undetectable by angiography. These differences in image interpretation raise the question of the validity of the categorization of images of the vessel site. In this study, we classified each image site as normal, stable atheroma, disrupted atheroma, or thrombus. To establish a histopathologic validation for angioscopic and ultrasound image classification, we have recorded images from postmortem human coronary and peripheral vessels, and compared these results with independent histologic categorization.6 Angioscopic classification agreed with the histologic classification in 79% of the cases; ultrasound classification correlated with histology at 93% of the sites.‘j All the differences in image classification involved cross-classification between stable and disrupted atheroma. Although we observed that angiography has significant limitations for detailed analysis of individual vascular sites, we found that it was substantially su-
Volume Number
120 5
Imaging
techniques
after PTA
1089
Fig. 2. A, Baselineangiogramshowsa total occlusionof the superficial femoral artery. B, Angiogram after percutaneousballoon angioplasty revealsarterial recanalization and a smooth appearanceof the lumen. C, Baseline angioscopy demonstratesstable atheroma (yellow, white areas). Arrow identifies distal lumen from which blood (red) is flowing retrograde toward the angioscope.D, Following balloon angioplasty, angioscopyshowsdisruption of the atheroma and a portion of the intima is showntorn, mobile, and protruding into the lumen. E, Baselineultrasound imagefrom the proximal portion of the arterial stenosisdemonstrates arterial narrowing by concentric atherosclerotic plaque. F, The ultrasound image after balloon angioplasty documentsthe disruption of the atheroma with arrows identifying a site of arterial dissection (separation of the plaque from the arterial wall).
perior to angioscopy and ultrasound
for analyzing the entire vascular tree. Since the outer diameter of both the angioscopic and ultrasound catheters is unlikely to become less than 0.5 mm, we believe that the use of these systems will be for detailed analyses of indi-
vidual sites, and will thus be complementary to angiography. In contrast to angiography, angioscopy was particularly well suited for detection of abnormalities of the vessel surface, including subintimal hemorrhage and intimal flaps. Ultrasound was found
1090
Siegel et al.
to be most useful for analysis of lumen morphology and diameter, wall thickness, and the presence of intramural dissection. In practical application, intravascular imaging data may be useful for both understanding the pathogenesis of vascular syndromes and for altering operator decisions during therapeutic vascular procedures. We have previously7 used coronary angioscopy to establish the type and frequency of intimal pathology in stable angina and acute coronary syndromes. We found a strong correlation between symptom classification and the angioscopic appearance of the coronary artery. Specifically, 94% of patients with stable angina had stable atheroma, whereas 92 % of patients with acute coronary syndromes had intimal disruption or partially occlusive thrombus. Acute coronary syndromes also occur in approximately 7% of coronary angioplasty procedures,8; we speculate that there may be a similar correlation between the angioplasty-induced magnitude or type of intimal damage and acute closure. It may also be gossible to demonstrate a relationship between either pre-or post-angioplasty images and late restenosis. There is increasing evidence that restenosis is a hyperplastic response of the myointima to tearing and stretching injury.g Despite evidence of substantial vascular injury induced by angioplasty, however, our two cases had no acute complications and have no clinical evidence of restenosis at 3 and 4 months, respectively. Nevertheless, we believe that correlating the classification of images of the blood vessel surface and wall with acute and late complications could provide a clearer understanding of the pathogenesis of both acute closure and restenosis. The potential value of intravascular imaging to guide or alter interventional or surgical therapy is also illustrated by our two cases. In our first case, a thrombus was detected by angioscopy and was removed by aspiration. Grundfest et allo reported that in 85 peripheral vascular surgeries in which angioscopy was employed, the data provided to the surgeon altered management in 25% of the cases. Hofling et all1 performed percutaneous peripheral vascular angioscopy in 10 patients with 15 stenoses during and after atherectomy. Angioscopy of the treated areas revealed flaps or obstructing residual material at 4 of the 15 angioplasty sites. Based on this information, additional passages of the atherectomy catheter were used to improve the therapeutic outcome. Despite these and other reports, however, neither angioscopy nor ultrasound has yet achieved widespread acceptance as a clinical tool. In our experience, the major limitation of both imaging techniques is that the systems are not yet easy to use. Our early experience
suggests that ultrasound could ultimately be easier to use than angioscopy, however, because flushing of blood during imaging is not required. In conclusion, our case reports show that important intravascular abnormalities such as partially occlusive thrombus, intimal flaps, and vascular dissections may not be detected by angiography. We found that each of the three imaging modalities has an independent value: angiography is superior for visualizing the entire vascular bed, angioscopy for assessing the vascular surface, and ultrasound for evaluating the blood vessel wall. Together these imaging modalities may help to define the pathogenesis of acute closure and reetenosis after angioplasty. It is also possible that with increased ease of use, these devices could be used to aid decision-making during intravascular interventions. The authors thank Ms. Ann Cummings for her word processing assistance.
REFERENCES
1. Ambrose JA, Winters SL, Arora RR. Coronary angiographic morphology and the pathogenesis of unstable angina pectoris. J Am Co11Cardiol 1985;5:609-16. 2. Potkin BN. Roberts WC. Effects of nercutaneous transluminal coronary angioplasty on athero&erotic plaque and relation of plaque composition and arterial size to outcome. Am J Cardiol 1988;62:41-50. 3. Uchida Y, Hasegawa K, Kawamura K, Shibuya I. Angioscopic observation of the coronary luminal changes induced by percutaneous transluminal coronary angioplasty. AM HEARTJ 1989;117:769-76. 4. Johnson C, Hansen DD, Vracko R, Ritchie J. Angioscopymore sensitive for identifying thrombus, distal emboli, and subintimal dissection [Abstract]. J Am Co11 Cardiol 1989;13:146A. 5. Van Stiegmann G, Pearce WH, Bartle EJ, Rutherford RB. FIexible angioscopy seems faster and more specific than arteriography Arch Surg 1987;122:279-82. 6. Siegel RJ, Fishbein MC, Chae JS, Helfant RJ, Hickey A, Forrester JS. Comparative studies of angioscopy and ultrasound for the evaluation of arterial disease. Echocardiography 1990;7:495-502. I. Sherman CT, Litvack F, Grundfest W, Lee M, Hickey A, Chaux A, Kass R, Blanche C, Matloff J, Morgenstern L, Ganz W, Swan HJC, Forrester J. Coronary angioscopy in patients with unstable angina pectoris. N Engl J Med 1986;315:913-9. a. Detre K, Holubkov R, Kelsey S, Bourassa M, Williams D, Holmes D Jr, Dorros G, Faxon D, Myler R, Kent K, Cowley M, Cannon R, Robertson T. One-year follow-up results of the 19851986 National Heart, Lung, and Blood Institute’s percutaneous transluminal coronary angioplasty registry. Circulation 1989;80:421-8. 9. Forrester JS, Fishbein M, Helfant R, Fagin J. The cellular and molecular biology of restenosis after angioplasty. J Am Co11 Cardiol (In press, 1990) 10. Grundfest WS, Litvack F, Glick D, Segalowitz J, Treiman R, Cohen L, Foran R, Levin P, Cossman D, Carroll R, Spigelman A, Forrester JS. Intraoperative decisions based on angioscopy in peripheral vascular surgery. Circulation 1988;78(suppl I):I13-7. 11. Hofling G, Polnita A, Bauriedel G, Backa D, Lauterjung L, Simpson J. Use of angioscopy to assess the results of percutaneous atherectomy. Am J Cardiac Imaging 1989;3:20-6.
Robert J. Siegel, MD, Jang-Seong Chae, MD, James S. Forrester, MD, and Carlos E. Ruiz, MD. Los Angeles, Calif.
Angiography defines the contour of the blood vessel wall but provides only inferential information about abnormalities of the blood vessel surface and wa1l.l Although intravascular angioscopy and ultrasound, which image the vessel surface and wall directly, could supplement the diagnostic information provided by angiography, there is no report about the use of these techniques in combination. In this communication we report our experience in our first two patients in whom we combined the use of angiography, angioscopy, and ultrasonic imaging before and after percutaneous peripheral transluminal angioplasty (PTA). The cases illustrate important differences in the information obtained by each technique, and suggest that both an insight into the pathogenesis of vascular syndromes and an alteration of operator behavior during intervention may result from the use of intravascular imaging technologies. METHODSANDRESULTS Case No. 1. This patient wasa 72-year-old man with a history of SO-yardclaudication. On physical examination, the right pedal pulsewasnot palpable. After local lidocaine
From Heart
the Divisions of Cardiology, Cedars-Sinai Medical Institute, The Hospital of The Good Samaritan.
Received Reprint Beverly 411123427
1086
for publication requests: Robert Blvd., Cardiology
April
16. 1990;
d. Siegel, Room
accepted
June
MD, Cedars-Sinai 5314, Los Angeles,
Center,
and The
1, 1990.
Medical Center, CA 90048-0750.
8700
analgesia,an 8F arterial sheath wasplaced in an antegrade direction in the ipsilateral femoral artery by percutaneous catheterization. Angiography wasperformed with Hexabrix contrast medium (Mallinckrodt Medical, St. Louis, MO.). Angioscopy was performed with a 1 mm angioscope,light source,and an occlusionballoon (Baxter Healthcare Corp., EdwardsDivision, Santa Ana, Calif.). A pressurizedsystem was used to flush crystalloid solution to obtain a clear viewing field. Subsequently, an SF 20 MHz ultrasound imaging catheter (Cardiovascular Imaging Systems, Sunnyvale, Calif.) was inserted into the vesseland was passed under fluoroscopic guidanceto the distal tibia1 artery. No flushing wasrequired for imaging.Ultrasound imagingwas performed during antegrade passageand pullback of the catheter. Angioscopic and ultrasonic imageswere viewed on a high resolution monitor (Sony Medical Electronics, Park Ridge, N.J.) and wererecorded on l/2-inch videotape. After the baselineimaging with angiography, angioscopy, and ultrasound, balloon angioplasty wasperformed on the stenotic segments.Subsequently, all three imaging methods were repeated. Fig. 1, A, C, E, and G demonstrate the angiographic,angioscopic,and ultrasonographic imagesrecorded prior to angioplasty. By angiography there is a smooth 4 cm long narrowing in the posterior tibia1 artery (Fig. 1, A). This lesion was classifiedas a stable atheroma causinga 75% diameter stenosis. In contrast, angioscopy of this site showeda raisedred massthat wasclassifiedasa thrombus (Fig. 1, C). Based on this image, the masswas extracted from the vessel by aspiration. Subsequent pathologic examination showedit to be a thrombus. The remainder of the vesselhad a yellow-white surfacewith smoothelevated
Volume
120
Number
5
Imaging
techniques
after PTA
1087
Fig. 1. A, Baselineangiogramof posterior tibia1 artery. Arrows denote smooth4 cm long stenosis.6, Angiogram after percutaneousballoon angioplasty reveals a smooth lumen at the angioplasty sites (arrows). C, Angioscopy identifies a red smooth intralumenal mass(arrows) that wasseenand removed prior to ultrasound imaging and angioplasty. D, Angioscopy following angioplasty revealsintimal tear, identified by arrows, not evident by angiography. E, Baselineultrasound imageat the site of the proximal arrow on angiogram (panel B) reveals a narrowed lumen with thickened walls, consistent with atherosclerotic plaque. F, After angioplasty, ultrasound demonstratesa tear and separationof the arterial plaque down to the level of the adventitia. G, Baselineultrasound, at site of distal arrow on angiogram(B) revealsa narrowed lumen with increased echodensity and acoustic shadowing, suggestingcalcification. H, Following angioplasty, fragmentation of the plaque is evident (arrows).
lesions of various sizes, which were classified as stable atheroma. After aspiration of the thrombus, intravascular ultrasound imaging wasperformed. The vesselsurfacewas smooth, and the lumen wasdiffusely narrowed, ultrasound
also demonstrated increasedwall thickness at the site of the raised lesions.Basedon these findings, the vesselwas classifiedas exhibiting diffuse stable atherosclerotic disease(Fig. 1, E). The luminal areawasmeasuredas8.3 mm2
1990
1088
Siegel et al.
in the nondiseasedportion of the vessel,and as2.2 mm2at the most severe stenosis.In addition, we noted increased echo density at the stenotic site, suggestiveof calcification (Fig. 1, G). Theselatter data combined with decreasedarterial pulsation were interpreted as suggestingthat high inflation pressuresmight be required during dilatation. Angioplasty was then performed with a 2.5 mm Meditech (Medi-tech Inc., Watertown, Mass.) balloon catheter using manual inflation for 2 minutes with a 10 cm3syringe containing Hexabrix contrast material. Fig. 1, B, D, F, and H show the angiographic, angioscopic,and ultrasonographic imagesfollowing balloon angioplasty. Angiography demonstrateda 25% residualstenosisat the angioplasty site (Fig. 1,B). The vesselsurfaceappears smooth, and there is no evidence of vascular injury or dissection.The angioscopicimage revealed two linear tears on oppositearterial walls that extended from the angioplasty site to the distal portion of the vessel(Fig. 1, D). There is focal disruption of the intimal surface and subintimal hemorrhage. The intravascular ultrasound image alsodocumentedtearing of the arterial plaque at the same two sites (Fig. 1, F). In addition, the depth and extent of the tear were revealed. The depth reachesthe arterial adventitia, and it extends from the mid to the distal segment of the vessel (Fig. 1, H). The angiographic impressionof increasedluminal diameter was confirmed by direct measurement: the lumen area increasedfrom 8.2 to 8.9 mm2 proximally, and from 2.3 to 2.9 mm2in the distal arterial segment. CaseNo. 2. This patient wasa 75-year-old man with a 5-year history of intermittent claudication, who presented with resting right calf pain. On physical examination, the right popliteal and distal arteries were not palpable. The right lower extremity wascooler than the left but without evidence of ulceration. Angiography, angioscopy, and ultrasound were performed as described in caseNo. 1 and again after intervention. In case No. 2, however, a stiff 0.35-inch guide wire wasusedto crossthe totally occluded segmentprior to balloon angioplasty. The superficial femoral artery wasdilated with a 4 mm Meditech (Medi-tech Inc.) peripheral angioplasty balloon usingmanual inflation for 5 minutes with a 10 cm3 syringe filled with Hexabrix contrast material. Fig. 2, A, C, and E showthe vascular imagesprior to angioplasty. Proximal to the complete occlusion, both the angiographicand angioscopicimagesshowed raised, smooth plaquesand the ultrasound imagedemonstrated a diffusely thickened arterial wall with a smooth lumen. Thus all three modalities gave information consistent with stable atheroma proximal to the total occlusion. Fig. 2,B, D, and F showthe angioplasty site following the procedure. Angiography demonstrated a smooth, residual lumen with antegradeflow to the distal extremity (Fig. 2, B). The residual diameter stenosiswas 65% by caliper measurement.In contrast, angioscopydemonstrated a severely disrupted intimal surface. There were intimal flaps and a region in which the arterial plaque appeared fractured (Fig. 2, D). By ultrasound, an echolucent zone was localized within the plaque. This zone extends 3 cm down the vesseland then reentersthe arterial lumen. This image was classifiedas disrupted atheroma with an arterial dis-
American
November Heart Journal
section (Fig. 2, F). The residual luminal area at the angioplasty site was 5.2 mm2. DISCUSSION
Our case studies demonstrate striking differences in diagnostic conclusions derived from three intravascular imaging techniques. Prior to PTA in case No. 1, an angiographic image classified as a smooth atheroma was found to be a partially occlusive thrombus by angioscopy. After PTA in case No. 2, the intimal surface considered smooth by angiography was found by angioscopy and ultrasound to have evidence of extensive intimal damage, including subintimal hemorrhage, intimal flaps, and dissection at the angioplasty site. Our results are part of an emerging body of evidence that angiographic analysis of the vessel after angioplasty does not reveal the extent of vascular damage. In a postmortem study of 26 patients who died after coronary angioplasty, Potkin and Roberts2 found that 98% of angioplasty sites had intimal disruption. Uchida et al3 found that of 10 sites exhibiting intimal hemorrhage and disruption by percutaneous angioscopy after PTCA, seven were read as normal by angiography. There have also been several comparisons of angiography and angioscopy. Johnson et a1.4 found subintimal dissection 26 times by angioscopy, whereas cineangiography did not demonstrate even one of the flaps, and thrombus was present in 30 angioscopic images but was detected by angiography in only 11. Van Stiegmann et al5 found angioscopic endovascular abnormalities undetected by angiography in 26% of patients. Angioscopy revealed free-floating clots, membrane-like obstructions, and atherosclerotic debris undetected by angiography. These data support the conclusion that unique and important information about the blood vessel may be undetectable by angiography. These differences in image interpretation raise the question of the validity of the categorization of images of the vessel site. In this study, we classified each image site as normal, stable atheroma, disrupted atheroma, or thrombus. To establish a histopathologic validation for angioscopic and ultrasound image classification, we have recorded images from postmortem human coronary and peripheral vessels, and compared these results with independent histologic categorization.6 Angioscopic classification agreed with the histologic classification in 79% of the cases; ultrasound classification correlated with histology at 93% of the sites.‘j All the differences in image classification involved cross-classification between stable and disrupted atheroma. Although we observed that angiography has significant limitations for detailed analysis of individual vascular sites, we found that it was substantially su-
Volume Number
120 5
Imaging
techniques
after PTA
1089
Fig. 2. A, Baselineangiogramshowsa total occlusionof the superficial femoral artery. B, Angiogram after percutaneousballoon angioplasty revealsarterial recanalization and a smooth appearanceof the lumen. C, Baseline angioscopy demonstratesstable atheroma (yellow, white areas). Arrow identifies distal lumen from which blood (red) is flowing retrograde toward the angioscope.D, Following balloon angioplasty, angioscopyshowsdisruption of the atheroma and a portion of the intima is showntorn, mobile, and protruding into the lumen. E, Baselineultrasound imagefrom the proximal portion of the arterial stenosisdemonstrates arterial narrowing by concentric atherosclerotic plaque. F, The ultrasound image after balloon angioplasty documentsthe disruption of the atheroma with arrows identifying a site of arterial dissection (separation of the plaque from the arterial wall).
perior to angioscopy and ultrasound
for analyzing the entire vascular tree. Since the outer diameter of both the angioscopic and ultrasound catheters is unlikely to become less than 0.5 mm, we believe that the use of these systems will be for detailed analyses of indi-
vidual sites, and will thus be complementary to angiography. In contrast to angiography, angioscopy was particularly well suited for detection of abnormalities of the vessel surface, including subintimal hemorrhage and intimal flaps. Ultrasound was found
1090
Siegel et al.
to be most useful for analysis of lumen morphology and diameter, wall thickness, and the presence of intramural dissection. In practical application, intravascular imaging data may be useful for both understanding the pathogenesis of vascular syndromes and for altering operator decisions during therapeutic vascular procedures. We have previously7 used coronary angioscopy to establish the type and frequency of intimal pathology in stable angina and acute coronary syndromes. We found a strong correlation between symptom classification and the angioscopic appearance of the coronary artery. Specifically, 94% of patients with stable angina had stable atheroma, whereas 92 % of patients with acute coronary syndromes had intimal disruption or partially occlusive thrombus. Acute coronary syndromes also occur in approximately 7% of coronary angioplasty procedures,8; we speculate that there may be a similar correlation between the angioplasty-induced magnitude or type of intimal damage and acute closure. It may also be gossible to demonstrate a relationship between either pre-or post-angioplasty images and late restenosis. There is increasing evidence that restenosis is a hyperplastic response of the myointima to tearing and stretching injury.g Despite evidence of substantial vascular injury induced by angioplasty, however, our two cases had no acute complications and have no clinical evidence of restenosis at 3 and 4 months, respectively. Nevertheless, we believe that correlating the classification of images of the blood vessel surface and wall with acute and late complications could provide a clearer understanding of the pathogenesis of both acute closure and restenosis. The potential value of intravascular imaging to guide or alter interventional or surgical therapy is also illustrated by our two cases. In our first case, a thrombus was detected by angioscopy and was removed by aspiration. Grundfest et allo reported that in 85 peripheral vascular surgeries in which angioscopy was employed, the data provided to the surgeon altered management in 25% of the cases. Hofling et all1 performed percutaneous peripheral vascular angioscopy in 10 patients with 15 stenoses during and after atherectomy. Angioscopy of the treated areas revealed flaps or obstructing residual material at 4 of the 15 angioplasty sites. Based on this information, additional passages of the atherectomy catheter were used to improve the therapeutic outcome. Despite these and other reports, however, neither angioscopy nor ultrasound has yet achieved widespread acceptance as a clinical tool. In our experience, the major limitation of both imaging techniques is that the systems are not yet easy to use. Our early experience
suggests that ultrasound could ultimately be easier to use than angioscopy, however, because flushing of blood during imaging is not required. In conclusion, our case reports show that important intravascular abnormalities such as partially occlusive thrombus, intimal flaps, and vascular dissections may not be detected by angiography. We found that each of the three imaging modalities has an independent value: angiography is superior for visualizing the entire vascular bed, angioscopy for assessing the vascular surface, and ultrasound for evaluating the blood vessel wall. Together these imaging modalities may help to define the pathogenesis of acute closure and reetenosis after angioplasty. It is also possible that with increased ease of use, these devices could be used to aid decision-making during intravascular interventions. The authors thank Ms. Ann Cummings for her word processing assistance.
REFERENCES
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