Intravenous Digital Subtraction Arteriography in the Evaluation of Vascular Grafts F. Michael Ameli, MB, ChB, FRCS (Ed), FRCS (C), FACS, Michael S. Rooney, MD, FRCP (C), Eugene L. St. Louis, MD, FRCP (C), Moni Stein, MD, Harvey Grosman, MD, FRCP (C), Robin R. Gray, MD, FRCP (C), Toronto, Ontario, Canada
Between 1982 and 1986 intravenous digital subtraction arteriography was used to evaluate vascular grafts in 97 patients (54 males, 43 females). Indications included recurrent symptoms, absent or diminished pulses, a drop in Doppler pressure measurements, and clinical uncertainty with respect to graft patency. Problems identified included graft stenosis, stenosis of the anastomosis or its distal vessels, false aneurysm, arteriovenous fistula and emboli. Forty-eight operations were carried out following intravenous digital subtraction arteriography, and radiographic findings were verified surgically. Twice, intravenous digital subtraction arteriography did not show significant graft findings which were discovered at surgery. Thus intravenous digital subtraction arteriography showed a sensitivity of 95.8% and specificity of 100%. Complications following intravenous digital subtraction arteriography were: two patients developed urticaria, and one superficial thrombophlebitis. There were no cases of pulmonary edema or death. In conclusion intravenous digital subtraction arteriography is very useful in the diagnosis of graft-related problems if done on a selective basis looking at graft and anastomosis site only. intravenous digital subtraction arteriography is done on an outpatient basis, has high sensitivity and specificity, good patient acceptance, is safe, fast and is less expensive than conventional arteriography. (Ann Vasc Surg 1991;5:223-228). KEY WORDS: Digital subtraction arteriography; intravenous digital subtraction arteriography See digital subtraction arteriography; graft evaluation.
Evaluation of postoperative vascular graft function is a complex task involving the integration of history, physical examination, laboratory and diagnostic imaging methods. The desire to investigate graft function with minimal morbidity has led to the From the Department of Vascular Surgery, and the Department of Radiology and Diagnostic Imaging, Wellesley Hospital, University of Toronto, Toronto, Canada. Reprint requests: Dr. F. Michael Ameti, 160 Wellesley Street East, Suite 313, E.K. Jones Building, Toronto, Ontario, M4 Y l J3 Canada.
development of alternative diagnostic procedures including the use of Doppler flow studies which are able to provide considerable information about graft function in a completely noninvasive manner. The limitation of this method is its inability to locate the exact anastomotic site and specific nature of an abnormality. The gold standard continues to be arterial arteriography. This procedure provides high resolution definition of the graft and vascular tree but requires an arterial puncture with injection of iodinated contrast material. With the development of intravenous digital subtraction arteriography (IV DSA) the question has
223
224
INTRA VENOUS DIGITAL SUBTRACTION A R T E R I O G R A P H Y
arisen as to its role in the evaluation of graft related problems. This study was undertaken to examine the usefulness of IV DSA as a replacement for arterial arteriography in the evaluation of postoperative vascular grafts.
MATERIALS AND METHODS Ninety-seven patients were admitted for clinical investigation of problems associated with vascular grafts. These patients underwent a total of 112 IV DSA examinations in a four year period from 1982 to 1986. These included 54 males and 43 females ranging in age from 39 to 82 years (mean = 62 years). All of these patients were admitted to our institution under the care of a vascular surgeon for investigation and treatment of graft problems. All patients had a careful history and physical examination carried out and all were examined noninvasively using Doppler studies and transcutaneous oxygen measurements. Patients considered suitable for the IV DSA study were those who: presented with recurrent claudication or symptoms and signs of severe ischemia such as night or rest pain. Other patients presented with reduced peripheral pulses or absent graft pulse with reduction in flow studies. Other concerns regarding the graft were: infection, false aneurysm, and patients who developed harsh bruits over the anastomosis. More recently, in situ femoropopliteal bypasses were evaluated with regard to arteriovenous fistula and graft stenosis. A careful discussion was then carried out between the surgeon and the vascular radiologist regarding the information that was required. We felt it essential that the proximal end of the graft and the inflow and outflow vessels be visualized along with the mid graft. Patients who required complete arteriography from the renal arteries down to the pedal arch were excluded from this study. All studies were reviewed by both the staff surgeon and the staff radiologist. On the basis of the information available a presumptive diagnosis was made. Those patients who then had further surgery were identified and correlation was made between the operative findings and the IV DSA findings. The equipment used was an ADAC DPS unit*, interfaced to a Siemens high velocity triple mode intensifier?. The image intensifier was mounted on an Angioskop systemw in one room and in a second arteriography room to a CGR Prestilix Angio unit**, which also had a triple mode image intensifier. All images were acquired on a 512 x 512 matrix and those done on the Siemens unit had CECG grating. A 5 French pigtail catheter was introduced into the right atrium either through the brachial vein
ANNALS OF VASCULAR SURGERY
(90%) or a femoral vein (10%). A volume of 50-60 cc of contrast was then injected at a rate of 22 cc/sec (80% of the studies used ionic agents, since many of the studies were performed before the availability of the nonionic agents). Intravenous glucagon was used for the abdominal cases. The field size was 9, 12 or 14 inches. All exposures were AP except the origins of the femoropopliteal grafts which were approximately 60 degrees oblique to demonstrate the profunda origin and the distal femoropopliteals which were done approximately 30 degrees oblique to open the trifurcation runoffs. The data obtained by IV DSA was then analyzed to determine graft stenosis, stenosis of the anastomosis or distal vessels, false aneurysm, and the presence of arteriovenous fistulae and emboli. Sensitivity and specifity of IV DSA were calculated based on the comparison between surgical and radiological findings.
RESULTS Ninety-seven consecutive patients were entered into the study with a total of 112 IV DSA examinations performed (some patients had more than one graft site). All patients had noninvasive studies including Doppler, spectral analysis, and transcutaneous oxygen studies prior to the arteriogram. The type of grafts looked at included: aortobifemoral (42), femoral-popliteal (37), in situ (femoral-popliteal) (6), axillofemoral (9), femorofemoral crossover (5), ascending aortobifemoral (3), popliteal patch (3), external iliac profunda (2), aorto-renal (2), common femoral patch (1), aorto-superior mesenteric artery (I), and femoral peroneal (1). Of the 43 femoral popliteal grafts investigated (37 femoral-popliteal and 6 in situ), 23 were patent and 20 occluded, five patients had stenosis distal to the graft insertion, two had false aneurysm, one had an arteriovenous fistula, and one had a popliteal embolus. In 42 aortobifemoral grafts, 33 were patent, nine had stenosis, nine had occlusions of one or both limbs of the graft. As well, there were four false aneurysms and 11 stenoses distal to the graft insertion. There was a single case of a kinked limb of the graft. Of the remaining 27 grafts, 18 were patent and nine occluded. Of the patent grafts, two had graft stenosis and 11 had stenosis distal to graft insertion. Following the IV DSA examinations 48 operations were carried out and the radiographic findings were verified surgically. There were two differences between surgical and IV DSA findings. Twice IV DSA did not show significant graft findings which were discovered at surgery (two false negatives). Thus, sensitivity of IV DSA was 95.8%. There were no false positives and therefore specificity was 100%.
VOLUM~ 5 N o 3 - 1991
I N T R A V E N O U S DIGITAL SUBTRACTION A R T E R I O G R A P H Y
225
%
j ~=.
@..
J
~
,
~
.%..
N
/
~~ , , , =
,;~ ......
%
i
,
~: "i
Fig. 1. Intravenous digital subtraction arteriography is ideally suited to demonstrate normal graft function (a) as seen in widely patent left limb of aortobifemoral graft; (b) in left-to-right femorofemoral crossover graft; and (c) in distal insertion of femoropopliteal graft.
~! 1
Complications were limited to three patients (3.1%) and included two cases of hives and a single case of superficial thrombophlebitis. No cases of cardiac arrest or pulmonary edema were encountered. With the increasing use of nonionic contrast agents, this complications rate will likely drop. Figures l(a), l(b), and l(c) show normal graft function in aortobifemoral, femorofemoral and femoropopliteal grafts, respectively. Figures 2(a) and 2(b) show occlusions of femoropopliteal grafts. Figure 3 shows a high grade stenosis at the insertion of an aortobifemoral graft.
DISCUSSION
:5:: :;,:~
The maintenance of adequate blood flow through a vascular graft is essential in order to provide adequate limb perfusion. Numerous complications, both early and late, can occur, leading to compromise of graft patency. These include stenosis, occlusion, false aneurysm formation, graft kinking
226
INTRA V E N O U S DIGITAL SUBTRACTION A R T E R I O G R A P H Y
ANNALS OF VASCULAR SURGERY
Fig. 2. Occlusion of vascular graft is also obvious, as seen in two examples, including (a) blockage of origin of femoropopliteal graft and (b) at distal insertion of femoropopliteal graft.
and progression of natural disease, plus other less common problems. Methods of postoperative follow-up included noninvasive Doppler flow measurements from which much information can be derived. Magnetic resonance imaging is a new modality that shows early promise in demarcating the vascular tree [1]. However, until this or some other modality is fully developed, arteriography using iodinated contrast medium will remain the mainstay of investigation and demonstration of graft-related anatomy, Our purpose in this study was to assess the role of
IV DSA in the evaluation of graft related problems. Specifically, we asked, can IV DSA replace arterial arteriography in this particular clinical setting? This question has been addressed to some degree by previous authors [2-5], but our study of 112 grafts in 97 patients over a four year period appears to be the largest series reported to date in English language publications dealing with this specific question. The patients in this study comprised all vascular graft patients requiring arteriography followed over a period from 1982 to 1986. Indications for arteriography included: changes in Doppler measure-
VOLUME 5 No 3 - 1991
INTRA VENOUS DIGITAL SUBTRACTION ARTERIOGRAPHY
.... ~
~h~ ,
!
'~i
..
Fig. 3, intravenous digital subtraction arteriography clearly demonstrates high grade stenosis at insertion of right limb of aortobifemoral graft, ments, recurrent symptoms, or changes in peripheral pulses. Of the 112 IV DSA examinations carried out, no technical failures occurred with diagnostic studies being obtained in all cases. The abnormalities demonstrated, as mentioned earlier, included stenosis, occlusion, graft kinking, aneurysm formation, and arteriovenous fistula. Incidental findings were also seen and included five cases of occluded inferior mesenteric arteries and one case each of iliac artery stenosis and aortic ectasia. Surgery was performed in 48 cases and comparisons were made between radiographic and surgical findings. Only twice did IV DSA fail to show significant graft pathology. Sensitivity and specificity of IV DSA were 95.8% and 100%, respectively. A similar, very high level of accuracy has been documented previously [6,7]. Obviously, since most negative studies would not undergo surgery, it would be possible to miss false negative results. This is however, unlikely, as an abnormal graft should cause symptoms of a severity that would likely bring it to the attention of the clinician.
227
The technique of IV DSA was first described by Kruger and associates in 1979 [8]. In the early stages of IV DSA it was expected to replace standard arteriography as the method of choice in the evaluation of all peripheral vascular disease. The initial enthusiasm waned as limitations became apparent. These included; high contrast dose, limited field of view, and limitations related to patient factors such as movement, cardiac function and bowel gas shadows [9,10]. Spatial resolution does not equal that of conventional film screen arteriography which can become a factor when dealing with small peripheral vessels. Kinneson and colleagues [11] suggested a "tailored" approach to the study of peripheral vascular disease in patients with certain clinical histories. He relied upon other modalities in an attempt to locate the area of major disease prior to IV DSA. In this way IV DSA can be used to examine a more specific region. The limitation of this approach is that it will miss asymptomatic disease. Intravenous digital subtraction arteriography is ideally suited for the evaluation of vascular grafts. This is true for several reasons. Intravenous digital subtraction arteriography can be used to confirm normal graft appearance and function (Fig. 1), while it is equally effective at confirming graft occlusion (Fig. 2) or graft related abnormality (Fig. 3). Most grafts can be fully demonstrated with only a few exposures. The relatively large size of most grafts negates any limitations due to spatial resolution. The less invasive nature of a venous injection is also of significant benefit both to the patient and clinician. The theoretical risks of IV DSA are essentially reduced to that of a contrast injection. In our series minor complications occurred in three patients and included two cases of urticaria and one case of superficial thrombophlebitis. Most patients found the hot flush associated with a central venous injection to be less unpleasant than the burning associated with an arterial injectionl The requirement for IV analgesia and sedation frequently necessary for an arterial injection is not necessary for a venous injection. An IV DSA study can usually be completed in less than one hour with the patient being discharged almost immediately after. The cost of IV DSA is roughly equal to arterial arteriography when performed on an outpatient basis. If hospital admission is required, then an arterial arteriogram becomes considerably more expensive. There is also a subgroup of patients in whom arterial puncture is undesirable or even contraindicated due either to recent or earlier surgery or clotting abnormalities. This is true especially if arterial access requires graft puncture. Limitations of this technique were not a significant problem. Overlapping of vessels can be overcome by the use of oblique views. In no case was an arterial study required to clarify the findings of an
228
INTRA V E N O U S DIGITAL SUBTRACTION A R T E R I O G R A P H Y
IV DSA. Theoretical limitations to the use of IV DSA do exist, although they were not a factor in our patient population. A significant degree of patient compliance is required and agitated or confused patients may be unsuitable. Iodinated contrast is nephrotoxic and can worsen renal function in patients with marginal renal reserve. Renal failure is a relative contraindication to any form of arteriography. Adequate cardiac function is also necessary as the injection is into the venous side of the cardiac circulation. Congestive heart failure for any reason is also a contraindication to the procedure. Although IV DSA has been used to evaluate specific laboratory or clinical concerns, the possibility~of using the technique as a postoperative screening method to find early or subclinical changes has also been suggested in the literature [12], the theory being that detection of lesions prior to the occlusion stage can lead to a better surgical result due to early intervention. This idea has merit but requires further clinical investigation. Intravenous digital subtraction arteriography is of particular value when clinical examination is equivocal, for example, in the case of a soft clinical finding for which the clinician does not want to subject the patient to a full arteriogram. Of particular importance is the early postoperative period when arterial puncture may be contraindicated. In a study that compared clinical impression (without using Doppler) to arteriography, Butler and coworkers [13] found that the clinical impression could be inaccurate. This was particularly true in the first postoperative week where four of nine (44%) clinical diagnoses were found to be incorrect. This rate fell sharply to only 6% (two errors in 35 cases) following the end of the first week. These results would suggest that, if any doubt exists as to the validity of Doppler or clinical studies, especially in the early postoperative period, then IV DSA should be performed to clarify the situation.
CONCLUSION In summary, we have found IV DSA to be a highly sensitive and specific method for examining
IIIIB
ANNALS OF
VASCULARSURGERY
vascular grafts when limited to the graft and anastomotic site. The test is easily performed on an outpatient basis, has high patient acceptance, and is safer than arterial arteriography.
REFERENCES 1. DUOULIN CL, HART HR. Magnetic resonance angiography. Radiology 1986;161:117-201. 2. CRUMMY AB, STROTHER CM, SACKETI" JF, et al. Computerized fluoroscopy: digital subtraction for intravenous angiocardiography and arteriography. A JR 1980;135:1131-1140. 3. CRUMMY AB, STROTHER CM, LIEBERMAN RP, et al. Digital video subtraction angiography for evaluation of peripheral vascular disease. Radiology 1981 ;141:33-37. 4. ARLART IP, MUTSCHENREITER S. Intravenous digital subtraction angiography in patients with femoral arteriovenous fistulae and ilio-iliac crossover graft. Cardiovasc Intervent Radiol 1985;8:64-67. 5. MYEROWITZ PD, SWANSON DK, TURNIPSEED WD. Applications of digilal subtraction angiography in cardiovascular diagnosis. Surg Clin N Am 1985;65(3):423-437. 6. POND GD, OSBORNE RW, CAPP MP, et al. Digital subtraction angiography of peripheral bypass procedures. A JR 1982;138:279-281. 7. TURNIPSEED WD, ARCHER CW. Postoperative surveillance: an effective means of detecting correctable lesions that threaten graft patency. Arch Surg 1985;120:324-328. 8. KRUGER RA, MISTRETTA CA, HOOK TL. Computerized fluoroscopy in real time for non invasive cardiovascular imaging. Preliminary studies. Radiology 1979;130(1):4%57. 9. GUNTHANER DF, WEXLER L, ENZMANN DR, et al. Evaiuation of peripheral vascular disease using digital subtraction angiography. Radiology 1983;147:393-398. 10. STACUL F, MAFFESANTI M, POZZI-MUSELLI R, et al. Digital subtraction angiography in postoperative evaluation of peripheral vascular disease. Europ J Radiol 1984;4:38--41. 11. KINNiSON M, PERLER BA, WHITE RI, et al. Tailored approach for evaluation of peripheral vascular disease: intravenous digital subtraction angiography. A JR 1984;142: 1205-1209. 12. WOLFE JH, LEA THOMAS M, JAMIESON CW, et al. Early diagnosis of femorodistal graft stenosis. Br J Surg 1987;74:268-270. 13. BUTTLER P, WILLIAMSON B. Intravenous digital subtraction angiography in patients with suspected bypass graft occlusion following surgery for peripheral vascular disease. Br J Radiol 1986;59:329-332.
Between 1982 and 1986 intravenous digital subtraction arteriography was used to evaluate vascular grafts in 97 patients (54 males, 43 females). Indications included recurrent symptoms, absent or diminished pulses, a drop in Doppler pressure measurements, and clinical uncertainty with respect to graft patency. Problems identified included graft stenosis, stenosis of the anastomosis or its distal vessels, false aneurysm, arteriovenous fistula and emboli. Forty-eight operations were carried out following intravenous digital subtraction arteriography, and radiographic findings were verified surgically. Twice, intravenous digital subtraction arteriography did not show significant graft findings which were discovered at surgery. Thus intravenous digital subtraction arteriography showed a sensitivity of 95.8% and specificity of 100%. Complications following intravenous digital subtraction arteriography were: two patients developed urticaria, and one superficial thrombophlebitis. There were no cases of pulmonary edema or death. In conclusion intravenous digital subtraction arteriography is very useful in the diagnosis of graft-related problems if done on a selective basis looking at graft and anastomosis site only. intravenous digital subtraction arteriography is done on an outpatient basis, has high sensitivity and specificity, good patient acceptance, is safe, fast and is less expensive than conventional arteriography. (Ann Vasc Surg 1991;5:223-228). KEY WORDS: Digital subtraction arteriography; intravenous digital subtraction arteriography See digital subtraction arteriography; graft evaluation.
Evaluation of postoperative vascular graft function is a complex task involving the integration of history, physical examination, laboratory and diagnostic imaging methods. The desire to investigate graft function with minimal morbidity has led to the From the Department of Vascular Surgery, and the Department of Radiology and Diagnostic Imaging, Wellesley Hospital, University of Toronto, Toronto, Canada. Reprint requests: Dr. F. Michael Ameti, 160 Wellesley Street East, Suite 313, E.K. Jones Building, Toronto, Ontario, M4 Y l J3 Canada.
development of alternative diagnostic procedures including the use of Doppler flow studies which are able to provide considerable information about graft function in a completely noninvasive manner. The limitation of this method is its inability to locate the exact anastomotic site and specific nature of an abnormality. The gold standard continues to be arterial arteriography. This procedure provides high resolution definition of the graft and vascular tree but requires an arterial puncture with injection of iodinated contrast material. With the development of intravenous digital subtraction arteriography (IV DSA) the question has
223
224
INTRA VENOUS DIGITAL SUBTRACTION A R T E R I O G R A P H Y
arisen as to its role in the evaluation of graft related problems. This study was undertaken to examine the usefulness of IV DSA as a replacement for arterial arteriography in the evaluation of postoperative vascular grafts.
MATERIALS AND METHODS Ninety-seven patients were admitted for clinical investigation of problems associated with vascular grafts. These patients underwent a total of 112 IV DSA examinations in a four year period from 1982 to 1986. These included 54 males and 43 females ranging in age from 39 to 82 years (mean = 62 years). All of these patients were admitted to our institution under the care of a vascular surgeon for investigation and treatment of graft problems. All patients had a careful history and physical examination carried out and all were examined noninvasively using Doppler studies and transcutaneous oxygen measurements. Patients considered suitable for the IV DSA study were those who: presented with recurrent claudication or symptoms and signs of severe ischemia such as night or rest pain. Other patients presented with reduced peripheral pulses or absent graft pulse with reduction in flow studies. Other concerns regarding the graft were: infection, false aneurysm, and patients who developed harsh bruits over the anastomosis. More recently, in situ femoropopliteal bypasses were evaluated with regard to arteriovenous fistula and graft stenosis. A careful discussion was then carried out between the surgeon and the vascular radiologist regarding the information that was required. We felt it essential that the proximal end of the graft and the inflow and outflow vessels be visualized along with the mid graft. Patients who required complete arteriography from the renal arteries down to the pedal arch were excluded from this study. All studies were reviewed by both the staff surgeon and the staff radiologist. On the basis of the information available a presumptive diagnosis was made. Those patients who then had further surgery were identified and correlation was made between the operative findings and the IV DSA findings. The equipment used was an ADAC DPS unit*, interfaced to a Siemens high velocity triple mode intensifier?. The image intensifier was mounted on an Angioskop systemw in one room and in a second arteriography room to a CGR Prestilix Angio unit**, which also had a triple mode image intensifier. All images were acquired on a 512 x 512 matrix and those done on the Siemens unit had CECG grating. A 5 French pigtail catheter was introduced into the right atrium either through the brachial vein
ANNALS OF VASCULAR SURGERY
(90%) or a femoral vein (10%). A volume of 50-60 cc of contrast was then injected at a rate of 22 cc/sec (80% of the studies used ionic agents, since many of the studies were performed before the availability of the nonionic agents). Intravenous glucagon was used for the abdominal cases. The field size was 9, 12 or 14 inches. All exposures were AP except the origins of the femoropopliteal grafts which were approximately 60 degrees oblique to demonstrate the profunda origin and the distal femoropopliteals which were done approximately 30 degrees oblique to open the trifurcation runoffs. The data obtained by IV DSA was then analyzed to determine graft stenosis, stenosis of the anastomosis or distal vessels, false aneurysm, and the presence of arteriovenous fistulae and emboli. Sensitivity and specifity of IV DSA were calculated based on the comparison between surgical and radiological findings.
RESULTS Ninety-seven consecutive patients were entered into the study with a total of 112 IV DSA examinations performed (some patients had more than one graft site). All patients had noninvasive studies including Doppler, spectral analysis, and transcutaneous oxygen studies prior to the arteriogram. The type of grafts looked at included: aortobifemoral (42), femoral-popliteal (37), in situ (femoral-popliteal) (6), axillofemoral (9), femorofemoral crossover (5), ascending aortobifemoral (3), popliteal patch (3), external iliac profunda (2), aorto-renal (2), common femoral patch (1), aorto-superior mesenteric artery (I), and femoral peroneal (1). Of the 43 femoral popliteal grafts investigated (37 femoral-popliteal and 6 in situ), 23 were patent and 20 occluded, five patients had stenosis distal to the graft insertion, two had false aneurysm, one had an arteriovenous fistula, and one had a popliteal embolus. In 42 aortobifemoral grafts, 33 were patent, nine had stenosis, nine had occlusions of one or both limbs of the graft. As well, there were four false aneurysms and 11 stenoses distal to the graft insertion. There was a single case of a kinked limb of the graft. Of the remaining 27 grafts, 18 were patent and nine occluded. Of the patent grafts, two had graft stenosis and 11 had stenosis distal to graft insertion. Following the IV DSA examinations 48 operations were carried out and the radiographic findings were verified surgically. There were two differences between surgical and IV DSA findings. Twice IV DSA did not show significant graft findings which were discovered at surgery (two false negatives). Thus, sensitivity of IV DSA was 95.8%. There were no false positives and therefore specificity was 100%.
VOLUM~ 5 N o 3 - 1991
I N T R A V E N O U S DIGITAL SUBTRACTION A R T E R I O G R A P H Y
225
%
j ~=.
@..
J
~
,
~
.%..
N
/
~~ , , , =
,;~ ......
%
i
,
~: "i
Fig. 1. Intravenous digital subtraction arteriography is ideally suited to demonstrate normal graft function (a) as seen in widely patent left limb of aortobifemoral graft; (b) in left-to-right femorofemoral crossover graft; and (c) in distal insertion of femoropopliteal graft.
~! 1
Complications were limited to three patients (3.1%) and included two cases of hives and a single case of superficial thrombophlebitis. No cases of cardiac arrest or pulmonary edema were encountered. With the increasing use of nonionic contrast agents, this complications rate will likely drop. Figures l(a), l(b), and l(c) show normal graft function in aortobifemoral, femorofemoral and femoropopliteal grafts, respectively. Figures 2(a) and 2(b) show occlusions of femoropopliteal grafts. Figure 3 shows a high grade stenosis at the insertion of an aortobifemoral graft.
DISCUSSION
:5:: :;,:~
The maintenance of adequate blood flow through a vascular graft is essential in order to provide adequate limb perfusion. Numerous complications, both early and late, can occur, leading to compromise of graft patency. These include stenosis, occlusion, false aneurysm formation, graft kinking
226
INTRA V E N O U S DIGITAL SUBTRACTION A R T E R I O G R A P H Y
ANNALS OF VASCULAR SURGERY
Fig. 2. Occlusion of vascular graft is also obvious, as seen in two examples, including (a) blockage of origin of femoropopliteal graft and (b) at distal insertion of femoropopliteal graft.
and progression of natural disease, plus other less common problems. Methods of postoperative follow-up included noninvasive Doppler flow measurements from which much information can be derived. Magnetic resonance imaging is a new modality that shows early promise in demarcating the vascular tree [1]. However, until this or some other modality is fully developed, arteriography using iodinated contrast medium will remain the mainstay of investigation and demonstration of graft-related anatomy, Our purpose in this study was to assess the role of
IV DSA in the evaluation of graft related problems. Specifically, we asked, can IV DSA replace arterial arteriography in this particular clinical setting? This question has been addressed to some degree by previous authors [2-5], but our study of 112 grafts in 97 patients over a four year period appears to be the largest series reported to date in English language publications dealing with this specific question. The patients in this study comprised all vascular graft patients requiring arteriography followed over a period from 1982 to 1986. Indications for arteriography included: changes in Doppler measure-
VOLUME 5 No 3 - 1991
INTRA VENOUS DIGITAL SUBTRACTION ARTERIOGRAPHY
.... ~
~h~ ,
!
'~i
..
Fig. 3, intravenous digital subtraction arteriography clearly demonstrates high grade stenosis at insertion of right limb of aortobifemoral graft, ments, recurrent symptoms, or changes in peripheral pulses. Of the 112 IV DSA examinations carried out, no technical failures occurred with diagnostic studies being obtained in all cases. The abnormalities demonstrated, as mentioned earlier, included stenosis, occlusion, graft kinking, aneurysm formation, and arteriovenous fistula. Incidental findings were also seen and included five cases of occluded inferior mesenteric arteries and one case each of iliac artery stenosis and aortic ectasia. Surgery was performed in 48 cases and comparisons were made between radiographic and surgical findings. Only twice did IV DSA fail to show significant graft pathology. Sensitivity and specificity of IV DSA were 95.8% and 100%, respectively. A similar, very high level of accuracy has been documented previously [6,7]. Obviously, since most negative studies would not undergo surgery, it would be possible to miss false negative results. This is however, unlikely, as an abnormal graft should cause symptoms of a severity that would likely bring it to the attention of the clinician.
227
The technique of IV DSA was first described by Kruger and associates in 1979 [8]. In the early stages of IV DSA it was expected to replace standard arteriography as the method of choice in the evaluation of all peripheral vascular disease. The initial enthusiasm waned as limitations became apparent. These included; high contrast dose, limited field of view, and limitations related to patient factors such as movement, cardiac function and bowel gas shadows [9,10]. Spatial resolution does not equal that of conventional film screen arteriography which can become a factor when dealing with small peripheral vessels. Kinneson and colleagues [11] suggested a "tailored" approach to the study of peripheral vascular disease in patients with certain clinical histories. He relied upon other modalities in an attempt to locate the area of major disease prior to IV DSA. In this way IV DSA can be used to examine a more specific region. The limitation of this approach is that it will miss asymptomatic disease. Intravenous digital subtraction arteriography is ideally suited for the evaluation of vascular grafts. This is true for several reasons. Intravenous digital subtraction arteriography can be used to confirm normal graft appearance and function (Fig. 1), while it is equally effective at confirming graft occlusion (Fig. 2) or graft related abnormality (Fig. 3). Most grafts can be fully demonstrated with only a few exposures. The relatively large size of most grafts negates any limitations due to spatial resolution. The less invasive nature of a venous injection is also of significant benefit both to the patient and clinician. The theoretical risks of IV DSA are essentially reduced to that of a contrast injection. In our series minor complications occurred in three patients and included two cases of urticaria and one case of superficial thrombophlebitis. Most patients found the hot flush associated with a central venous injection to be less unpleasant than the burning associated with an arterial injectionl The requirement for IV analgesia and sedation frequently necessary for an arterial injection is not necessary for a venous injection. An IV DSA study can usually be completed in less than one hour with the patient being discharged almost immediately after. The cost of IV DSA is roughly equal to arterial arteriography when performed on an outpatient basis. If hospital admission is required, then an arterial arteriogram becomes considerably more expensive. There is also a subgroup of patients in whom arterial puncture is undesirable or even contraindicated due either to recent or earlier surgery or clotting abnormalities. This is true especially if arterial access requires graft puncture. Limitations of this technique were not a significant problem. Overlapping of vessels can be overcome by the use of oblique views. In no case was an arterial study required to clarify the findings of an
228
INTRA V E N O U S DIGITAL SUBTRACTION A R T E R I O G R A P H Y
IV DSA. Theoretical limitations to the use of IV DSA do exist, although they were not a factor in our patient population. A significant degree of patient compliance is required and agitated or confused patients may be unsuitable. Iodinated contrast is nephrotoxic and can worsen renal function in patients with marginal renal reserve. Renal failure is a relative contraindication to any form of arteriography. Adequate cardiac function is also necessary as the injection is into the venous side of the cardiac circulation. Congestive heart failure for any reason is also a contraindication to the procedure. Although IV DSA has been used to evaluate specific laboratory or clinical concerns, the possibility~of using the technique as a postoperative screening method to find early or subclinical changes has also been suggested in the literature [12], the theory being that detection of lesions prior to the occlusion stage can lead to a better surgical result due to early intervention. This idea has merit but requires further clinical investigation. Intravenous digital subtraction arteriography is of particular value when clinical examination is equivocal, for example, in the case of a soft clinical finding for which the clinician does not want to subject the patient to a full arteriogram. Of particular importance is the early postoperative period when arterial puncture may be contraindicated. In a study that compared clinical impression (without using Doppler) to arteriography, Butler and coworkers [13] found that the clinical impression could be inaccurate. This was particularly true in the first postoperative week where four of nine (44%) clinical diagnoses were found to be incorrect. This rate fell sharply to only 6% (two errors in 35 cases) following the end of the first week. These results would suggest that, if any doubt exists as to the validity of Doppler or clinical studies, especially in the early postoperative period, then IV DSA should be performed to clarify the situation.
CONCLUSION In summary, we have found IV DSA to be a highly sensitive and specific method for examining
IIIIB
ANNALS OF
VASCULARSURGERY
vascular grafts when limited to the graft and anastomotic site. The test is easily performed on an outpatient basis, has high patient acceptance, and is safer than arterial arteriography.
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