- Email: [email protected]
Infrapopliteal bypasses to heavily calcified rock-like arteries
lnfrapopliteal Bypasses to Heavily Calcified Rock-Like Arteries Management and Results
Emko Aster, MD, New York, New York
Frank J. Velth, MD, New York, New York shella A. White Florea, RN, MA, New York, New York
Various degrees of arterial calcification are frequently noted during infrapopliteal bypass surgery. Although the presence of scattered areas of calcification in the recipient artery may not impose significant technical difficulties, heavily and circumferentially calcified distal arteries are generally considered to be surgically unapproachable. Over a 5 year period, we have encountered 36 patients with limb-threatening ischemia who were found to have rock-like distal vessels at operation. For these patients, rather than performing a primary major amputation, we have attempted a new technique to overcome the rigidity of the arterial wall, thereby allowing the performance of a bypass operation. The purpose of this study is threefold: to describe this new technique, to report on the longterm graft patency and limb salvage results utilizing this technique, and to compare these results with those obtained from noncalcified vessels and from vessels with lesser degrees of calcification. Patients and Methods Between June 1979 and December 1984, a total of 355 infrapopliteal arterial bypasses were performed in 298 patients at Montefiore Medical Center. There were 148 male and 150 female patients. Age at operation ranged from 39 to 99 years, with a mean age of 72 years. Cardiovascular risk factors were common, with 7’7percent of the patients being diabetic and 69 percent hypertensive. Critical ischemia was the sole indication for operation, with From the Division of Vascular Surgery, Monteflore Medical Center-Albert Einstein College of Medicine, New York, New York. Supported in part by the Manning Foundation, New York, New York. Requests for reprints should be addressed to Enrico Aster, M), Dlvisi~l of Vascular Surgery, Montefiote Medical Center, 111 East 210th Street, New York, New York 10467. Presented at the 14th Annual Meeting of the Society for Clinical Vascular Surgery, Orlando, Florida, April 9-13, 1986.
220
severe rest pain in 23 percent of the patients, nonhealing ischemic ulcer in 30 percent, and gangrene in 47 percent. Autogenous saphenous vein grafts were utilized in 169 of these bypasses, expanded polytetrafluoroethylene grafts in 163, and composite grafts in 23. Bypass inflow originated from the common femoral artery in 123 patients, the superficial femoral artery in 146, the popliteal artery in 69, and from one of the distal arteries in 17. The recipient arteries were the peroneal in 59 cases, the posterior tibial artery in 57 cases, and the anterior tibial artery in 121 cases. One hundred forty-six of these bypasses were performed when the pedal arch was either incomplete or absent, whereas in 209 bypasses, the pedal arch was intact. Each recipient artery was classified according to its degree of calcification as noted by the operating surgeon into one of the following groups: Group I (116 cases) none, Group II (203 cases) mild to moderate, and Group III (36 cases) severe. All groups were comparable for age, diabetic status, type of graft material, and angiographic runoff. Six of the patients in Group III were on long-term hemodialysis. Follow-up data were available in 96 percent of this population. Whenever possible, patients were seen 2 weeks after hospital discharge and every 2 months during the first postoperative year, every 3 to 4 months during the second year, and every 4 to 6 months thereafter. Graft patency was assessed by palpation of distal pulses and, when in doubt, it was objectively assessed by segmental limb pressure measurements and pulse volume recordings. Reappearance of ischemic manifestations, decreased distal pulses, or worsened noninvasive test results were all indications for angiographic evaluation. Cumulative life tables were constructed to evaluate graft patency and limb salvage rates. Statistical comparison of all life table curves was performed by the log-rank test. Our approach to infrapopliteal arteries has been previously reported [I]. If a circumferentially calcified recipient artery is identified, further mobilization is carried out 2 to 3 cm more distally in an attempt to identify any soft segment of artery that can be utilized as a site for distal control. Extreme care should be taken not to injure the
The American Journalol Surgery
lnfrapopliteal
Bypasses to Heavily Calcified Arteries
side branches of the artery during the dissection since they usually represent an important outflow source and their repair may be very difficult in the presence of severe calcification. As shown in Figure 1, the artery is partially fractured at 3 to 4 mm intervals with a hemostat. This maneuver renders the artery suitable for occlusion, incision, and suture placement. Vascular clamps are then applied with the distal one being placed at least 1 cm away from the anticipated arteriotomy site (Figure 1, center). The arteriotomy is performed with a no. 15 knife blade, and stay sutures are placed on either side of the arteriotomy to separate the rigid walls, allowing for thorough inspection of the lumen. As is also shown in Figure 1, intimal damage may occur as a result of the arterial fracturing (11 of 36 cases). If required, the distal portion of the arteriotomy can then be extended to allow repair of the intimal flap or flaps without having to reapply the distal clamp. The intimal flap should be carefully tacked down with interrupted U stitches (Figure 1, bottom). Completion angiograms are routinely performed to confirm the adequacy of such repairs, to verify the luminal integrity of the anastomosis and the occlusion clamp sites, and to rule out distal embolization.
Resutts Operative mortality at 30 days for the entire patient population was 5.6 percent. Most, deaths re-
sulted from myocardial infarction. The early graft failure rate within 30 days for Groups I, II, and III were 9 percent, 17 percent, and 25 percent, respectively. Of the nine early graft failures in Group III (severe calcification), the cause of failure could be attributed to a technical defect in only four cases. In three of these, the lumen of the recipient artery was less than 1 mm in diameter, and extensive damage to the intima was caused by the fracture technique. In the remaining case, a thick anterior plaque occupying more than 60 percent of the lumen also added to the complexity of the intimal repair. The graft patency results of the 11 cases in Group III which required one or more tacking sutures (4 early and 2 late failures) were not significantly different from the remaining 25 cases with no intimal damage (5 early and 5 late failures). Three year cumulative life table patency rates for Groups I, II, and III were 45 percent, 58 percent, and 47 percent, respectively (Figure 2). Although at, 1 year, the patency rate in Group III was lower than in Group I (54 percent versus 67 percent), by the second year the results were comparable. No statistically significant difference between the three groups was present by the log-rank test. As shown in Figure 3, cumulative limb salvage rates at 3 years for Groups I, II, and III were 66 percent, 73 percent, and 75 percent,, respectively. In all three groups, limb salvage results were superior to graft patency. Although 94 percent of the cases in which graft failure occurred within the first postoperative month resulted in major amputations, 52 percent of the limbs remained viable when graft
VOlume
152, August IS86
Flgwel.T~~erter)rIsp~~yhsclureddSto4mm fntervate wttf~a hemoetat clsmp, aMowfng for w tncfafoq ami euture placemen 1. center, etay slitwee are pfaced to kctfttate tfmmx# tnqwctkm of me adwt8t fumer~ A8 strorm, Intfmal danmge may occur. Bottom, fntem8pted U etttchee we used to tack down the fntfmal flap.
221
Aster et al
M
NoneW116)
e---o
Mild/Moderate
-
Severe w36)
h-203)
Flgure 2. Comparison of graft patency rates according to the degree of cab clflcatlon In the reclplent artery. Numbars of patfents at rkk for each group are shown at yearty httervak
Month5After Operation
occlusion occurred during or after the second postoperative month.
Calcium deposits in the arterial wall are principally located within the media, more specifically within the internal elastic membrane. Thus, the
calcified plaque is in closer proximity to the intima than to the adventitia. In fact, although our fracture technique injured the intima in almost a third of the cases, in no instance was the adventitia found to be perforated. The fracture technique was used in cases when the artery could not be occluded or entered with an ordinary scalpel or Potts scissors, and this occurred in approximately 10 percent of all
90
-
None
o---4
Mild/ModerateMO3)
-
Severe WM)
W116)
B
12
24 Month3 Nter Operation
222
I
36
Ffgure 3. Comparison of limb salvage rate8 accord/ng to the degree of Cal: clffcatlon fn the reclplent artery, Numbers of patfents at rtsk for each group are shown af year/y Intervala
The AmerlcsnJournalot Surgwy
lnfrapopliteal Bypasses to Heavily Calcified Arteries
infrapopliteal reconstructions. This relatively high percentage can be explained by the large number of diabetics in our patient population (77 percent). In addition, a bypass operation was not denied to patients on long-term hemodialysis nor for those patients with severe calcification on roentgenograms. One important factor in determining the acceptable results obtained with this technique is related to the careful repair of any intimal damage. Our previous experience has shown that local vessel endarterectomy is uniformly unsuccessful in distal bypasses. Even when the intima is raised by an atherosclerotic plaque, one should not be swayed by the temptation to perform an endarterectomy of this lesion. Instead, the edges of the plaque, if loose, should be anchored to the arterial wall with interrupted U stitches and the distal end of the graft tailored as a patch over this repair. In our experience, we noted that thick, small vessels with a luminal diameter of 1 mm or less, when accompanied by heavy calcification, had a high early failure rate (four of five bypasses). Theoretic disadvantages of the fracture technique, such as distal embolization of calcium fragments, increased intraoperative bleeding from the distal anastomosis, and false aneurysm have not yet been observed in our patients. Although the patency results for Groups I and III were less than 50 percent at 3 years, the limb salvage results were quite acceptable. The major contributing factor for this difference is that in many cases, the ischemic ulcer or amputation site had healed and remained so even after graft thrombosis had occurred [2,3]. The present data do not substantiate the general belief that severe arterial calcification should preclude attempts at limb salvage bypass surgery. Conversely, intraoperative measurements of outflow resistance and type of graft material utilized continue to be the most important predictors of outcome of infrapopliteal bypass [4-61. Summary Of the 355 consecutive infrapopliteal bypasses for limb salvage performed over a 5 year period at our institution, 116 (Group I) were to noncalcified vessels, 203 (Group II) were to vessels of varying degrees of calcification (mild to moderate), and 36 (Group III) were to heavily and circumferentially calcified arteries. A new intraoperative fracture technique was used to overcome the rigidity of the arterial wall in the latter group. Three year cumulative patency rates for Groups I, II, and III were 45 percent, 58 percent, and 47 percent, respectively. Comparable limb salvage rates for Groups I, II, and III were 66 percent, 73 percent, and 75 percent. No significant difference in patency or limb salvage results could be elicited between the three groups by the log-rank test. These findings suggest that arteri-
Volume 152, August 1956
al calcification is an invalid predictor of failure in small vessel bypasses. Even circumferentially calcified arteries, which are generally thought to be surgically unapproachable, should not be a deterrent to limb salvage attempts. References 1. Veith FJ, Gupta SK. Femoral-distal artery bypasses. in: Bergan JJ, Yao JST, eds. Operative techniques in vascular surgery. New York: Grune 8. Stratton, 1980:141-50. 2. Brewster DC, LaSalle AJ, Robinson JG, Strayhorn EC, Darling RC. Femoropopliteal graft failures: clinical consequences and success of secondary reconstructions. Arch Surg 1983:118:1043-7. 3. Veith FJ, Gupta SK, Samson RH, et al. Progress in limb salvage by reconstructive arterial surgery combined with new or improved adjunctive procedures. Ann Surg 1981; 194:386-401. 4. Aster E, Veith FJ, Morin, et al. Components of outflow resistance and their correlation with graft patency in lower extremity arterial reconstructions. J Vast Surg 1984;l: 817-28. 5. Aster E, Veith FJ, Morin L, et al. Quantitative assessment of outflow resistance in lower extremity arterial reconstructions. J Surg Res 1964;37:8-15. 6. Veith FJ, Gupta SK, Aster E, et al. Six year prospective multicenter randomized comparison of autologous saphenous vein and expanded polytetrafluoroethylene grafts in infrainguinal arterial reconstructions. J Vast Surg 1986;3:104-14.
Discussant (name unknown): Why do you have to attempt to crack the plaque? Why not apply some other technique for excluding the segment for the anastomosie and go right into the plaque? Bruce Fellows (Wilmington, DE): It seems to me that Fogarty catheter proximal and distal control may be better conceptually. In addition, it may be just as easy to enter the vessel, crack the plaque on the wall where you are going to work, and therefore perhaps have less of a thrombogenic surface when you do your bypass at the distal anastomosis. Sheldon M. Levin (San Francisco, CA): Instead of fracturing the whole vessel with possible damage to the wall, why not fracture the upper third, and leave the bottom two thirds intact? Enrico Aster (closing): Arterial reconstructions to heavily and circumferentially calcified distal vessels were limited to patients with critical ischemia. The fracture technique was utilized only when no soft arterial segment was found and the artery could not be incised with an ordinary scalpel or Potts scissors. Dr. Fellows, inserting catheters and inflating balloons in diseased arteries for control of back bleeding may be hazardous, especially when one is dealing with small vessels. Dr. Levin, fracturing only a third of the vessel would be very difficult using this technique. I am in the process of developing techniques that utilize ultrasonic principles to facilitate such procedures and to make them less traumatic to the intimal layer.
223
Emko Aster, MD, New York, New York
Frank J. Velth, MD, New York, New York shella A. White Florea, RN, MA, New York, New York
Various degrees of arterial calcification are frequently noted during infrapopliteal bypass surgery. Although the presence of scattered areas of calcification in the recipient artery may not impose significant technical difficulties, heavily and circumferentially calcified distal arteries are generally considered to be surgically unapproachable. Over a 5 year period, we have encountered 36 patients with limb-threatening ischemia who were found to have rock-like distal vessels at operation. For these patients, rather than performing a primary major amputation, we have attempted a new technique to overcome the rigidity of the arterial wall, thereby allowing the performance of a bypass operation. The purpose of this study is threefold: to describe this new technique, to report on the longterm graft patency and limb salvage results utilizing this technique, and to compare these results with those obtained from noncalcified vessels and from vessels with lesser degrees of calcification. Patients and Methods Between June 1979 and December 1984, a total of 355 infrapopliteal arterial bypasses were performed in 298 patients at Montefiore Medical Center. There were 148 male and 150 female patients. Age at operation ranged from 39 to 99 years, with a mean age of 72 years. Cardiovascular risk factors were common, with 7’7percent of the patients being diabetic and 69 percent hypertensive. Critical ischemia was the sole indication for operation, with From the Division of Vascular Surgery, Monteflore Medical Center-Albert Einstein College of Medicine, New York, New York. Supported in part by the Manning Foundation, New York, New York. Requests for reprints should be addressed to Enrico Aster, M), Dlvisi~l of Vascular Surgery, Montefiote Medical Center, 111 East 210th Street, New York, New York 10467. Presented at the 14th Annual Meeting of the Society for Clinical Vascular Surgery, Orlando, Florida, April 9-13, 1986.
220
severe rest pain in 23 percent of the patients, nonhealing ischemic ulcer in 30 percent, and gangrene in 47 percent. Autogenous saphenous vein grafts were utilized in 169 of these bypasses, expanded polytetrafluoroethylene grafts in 163, and composite grafts in 23. Bypass inflow originated from the common femoral artery in 123 patients, the superficial femoral artery in 146, the popliteal artery in 69, and from one of the distal arteries in 17. The recipient arteries were the peroneal in 59 cases, the posterior tibial artery in 57 cases, and the anterior tibial artery in 121 cases. One hundred forty-six of these bypasses were performed when the pedal arch was either incomplete or absent, whereas in 209 bypasses, the pedal arch was intact. Each recipient artery was classified according to its degree of calcification as noted by the operating surgeon into one of the following groups: Group I (116 cases) none, Group II (203 cases) mild to moderate, and Group III (36 cases) severe. All groups were comparable for age, diabetic status, type of graft material, and angiographic runoff. Six of the patients in Group III were on long-term hemodialysis. Follow-up data were available in 96 percent of this population. Whenever possible, patients were seen 2 weeks after hospital discharge and every 2 months during the first postoperative year, every 3 to 4 months during the second year, and every 4 to 6 months thereafter. Graft patency was assessed by palpation of distal pulses and, when in doubt, it was objectively assessed by segmental limb pressure measurements and pulse volume recordings. Reappearance of ischemic manifestations, decreased distal pulses, or worsened noninvasive test results were all indications for angiographic evaluation. Cumulative life tables were constructed to evaluate graft patency and limb salvage rates. Statistical comparison of all life table curves was performed by the log-rank test. Our approach to infrapopliteal arteries has been previously reported [I]. If a circumferentially calcified recipient artery is identified, further mobilization is carried out 2 to 3 cm more distally in an attempt to identify any soft segment of artery that can be utilized as a site for distal control. Extreme care should be taken not to injure the
The American Journalol Surgery
lnfrapopliteal
Bypasses to Heavily Calcified Arteries
side branches of the artery during the dissection since they usually represent an important outflow source and their repair may be very difficult in the presence of severe calcification. As shown in Figure 1, the artery is partially fractured at 3 to 4 mm intervals with a hemostat. This maneuver renders the artery suitable for occlusion, incision, and suture placement. Vascular clamps are then applied with the distal one being placed at least 1 cm away from the anticipated arteriotomy site (Figure 1, center). The arteriotomy is performed with a no. 15 knife blade, and stay sutures are placed on either side of the arteriotomy to separate the rigid walls, allowing for thorough inspection of the lumen. As is also shown in Figure 1, intimal damage may occur as a result of the arterial fracturing (11 of 36 cases). If required, the distal portion of the arteriotomy can then be extended to allow repair of the intimal flap or flaps without having to reapply the distal clamp. The intimal flap should be carefully tacked down with interrupted U stitches (Figure 1, bottom). Completion angiograms are routinely performed to confirm the adequacy of such repairs, to verify the luminal integrity of the anastomosis and the occlusion clamp sites, and to rule out distal embolization.
Resutts Operative mortality at 30 days for the entire patient population was 5.6 percent. Most, deaths re-
sulted from myocardial infarction. The early graft failure rate within 30 days for Groups I, II, and III were 9 percent, 17 percent, and 25 percent, respectively. Of the nine early graft failures in Group III (severe calcification), the cause of failure could be attributed to a technical defect in only four cases. In three of these, the lumen of the recipient artery was less than 1 mm in diameter, and extensive damage to the intima was caused by the fracture technique. In the remaining case, a thick anterior plaque occupying more than 60 percent of the lumen also added to the complexity of the intimal repair. The graft patency results of the 11 cases in Group III which required one or more tacking sutures (4 early and 2 late failures) were not significantly different from the remaining 25 cases with no intimal damage (5 early and 5 late failures). Three year cumulative life table patency rates for Groups I, II, and III were 45 percent, 58 percent, and 47 percent, respectively (Figure 2). Although at, 1 year, the patency rate in Group III was lower than in Group I (54 percent versus 67 percent), by the second year the results were comparable. No statistically significant difference between the three groups was present by the log-rank test. As shown in Figure 3, cumulative limb salvage rates at 3 years for Groups I, II, and III were 66 percent, 73 percent, and 75 percent,, respectively. In all three groups, limb salvage results were superior to graft patency. Although 94 percent of the cases in which graft failure occurred within the first postoperative month resulted in major amputations, 52 percent of the limbs remained viable when graft
VOlume
152, August IS86
Flgwel.T~~erter)rIsp~~yhsclureddSto4mm fntervate wttf~a hemoetat clsmp, aMowfng for w tncfafoq ami euture placemen 1. center, etay slitwee are pfaced to kctfttate tfmmx# tnqwctkm of me adwt8t fumer~ A8 strorm, Intfmal danmge may occur. Bottom, fntem8pted U etttchee we used to tack down the fntfmal flap.
221
Aster et al
M
NoneW116)
e---o
Mild/Moderate
-
Severe w36)
h-203)
Flgure 2. Comparison of graft patency rates according to the degree of cab clflcatlon In the reclplent artery. Numbars of patfents at rkk for each group are shown at yearty httervak
Month5After Operation
occlusion occurred during or after the second postoperative month.
Calcium deposits in the arterial wall are principally located within the media, more specifically within the internal elastic membrane. Thus, the
calcified plaque is in closer proximity to the intima than to the adventitia. In fact, although our fracture technique injured the intima in almost a third of the cases, in no instance was the adventitia found to be perforated. The fracture technique was used in cases when the artery could not be occluded or entered with an ordinary scalpel or Potts scissors, and this occurred in approximately 10 percent of all
90
-
None
o---4
Mild/ModerateMO3)
-
Severe WM)
W116)
B
12
24 Month3 Nter Operation
222
I
36
Ffgure 3. Comparison of limb salvage rate8 accord/ng to the degree of Cal: clffcatlon fn the reclplent artery, Numbers of patfents at rtsk for each group are shown af year/y Intervala
The AmerlcsnJournalot Surgwy
lnfrapopliteal Bypasses to Heavily Calcified Arteries
infrapopliteal reconstructions. This relatively high percentage can be explained by the large number of diabetics in our patient population (77 percent). In addition, a bypass operation was not denied to patients on long-term hemodialysis nor for those patients with severe calcification on roentgenograms. One important factor in determining the acceptable results obtained with this technique is related to the careful repair of any intimal damage. Our previous experience has shown that local vessel endarterectomy is uniformly unsuccessful in distal bypasses. Even when the intima is raised by an atherosclerotic plaque, one should not be swayed by the temptation to perform an endarterectomy of this lesion. Instead, the edges of the plaque, if loose, should be anchored to the arterial wall with interrupted U stitches and the distal end of the graft tailored as a patch over this repair. In our experience, we noted that thick, small vessels with a luminal diameter of 1 mm or less, when accompanied by heavy calcification, had a high early failure rate (four of five bypasses). Theoretic disadvantages of the fracture technique, such as distal embolization of calcium fragments, increased intraoperative bleeding from the distal anastomosis, and false aneurysm have not yet been observed in our patients. Although the patency results for Groups I and III were less than 50 percent at 3 years, the limb salvage results were quite acceptable. The major contributing factor for this difference is that in many cases, the ischemic ulcer or amputation site had healed and remained so even after graft thrombosis had occurred [2,3]. The present data do not substantiate the general belief that severe arterial calcification should preclude attempts at limb salvage bypass surgery. Conversely, intraoperative measurements of outflow resistance and type of graft material utilized continue to be the most important predictors of outcome of infrapopliteal bypass [4-61. Summary Of the 355 consecutive infrapopliteal bypasses for limb salvage performed over a 5 year period at our institution, 116 (Group I) were to noncalcified vessels, 203 (Group II) were to vessels of varying degrees of calcification (mild to moderate), and 36 (Group III) were to heavily and circumferentially calcified arteries. A new intraoperative fracture technique was used to overcome the rigidity of the arterial wall in the latter group. Three year cumulative patency rates for Groups I, II, and III were 45 percent, 58 percent, and 47 percent, respectively. Comparable limb salvage rates for Groups I, II, and III were 66 percent, 73 percent, and 75 percent. No significant difference in patency or limb salvage results could be elicited between the three groups by the log-rank test. These findings suggest that arteri-
Volume 152, August 1956
al calcification is an invalid predictor of failure in small vessel bypasses. Even circumferentially calcified arteries, which are generally thought to be surgically unapproachable, should not be a deterrent to limb salvage attempts. References 1. Veith FJ, Gupta SK. Femoral-distal artery bypasses. in: Bergan JJ, Yao JST, eds. Operative techniques in vascular surgery. New York: Grune 8. Stratton, 1980:141-50. 2. Brewster DC, LaSalle AJ, Robinson JG, Strayhorn EC, Darling RC. Femoropopliteal graft failures: clinical consequences and success of secondary reconstructions. Arch Surg 1983:118:1043-7. 3. Veith FJ, Gupta SK, Samson RH, et al. Progress in limb salvage by reconstructive arterial surgery combined with new or improved adjunctive procedures. Ann Surg 1981; 194:386-401. 4. Aster E, Veith FJ, Morin, et al. Components of outflow resistance and their correlation with graft patency in lower extremity arterial reconstructions. J Vast Surg 1984;l: 817-28. 5. Aster E, Veith FJ, Morin L, et al. Quantitative assessment of outflow resistance in lower extremity arterial reconstructions. J Surg Res 1964;37:8-15. 6. Veith FJ, Gupta SK, Aster E, et al. Six year prospective multicenter randomized comparison of autologous saphenous vein and expanded polytetrafluoroethylene grafts in infrainguinal arterial reconstructions. J Vast Surg 1986;3:104-14.
Discussant (name unknown): Why do you have to attempt to crack the plaque? Why not apply some other technique for excluding the segment for the anastomosie and go right into the plaque? Bruce Fellows (Wilmington, DE): It seems to me that Fogarty catheter proximal and distal control may be better conceptually. In addition, it may be just as easy to enter the vessel, crack the plaque on the wall where you are going to work, and therefore perhaps have less of a thrombogenic surface when you do your bypass at the distal anastomosis. Sheldon M. Levin (San Francisco, CA): Instead of fracturing the whole vessel with possible damage to the wall, why not fracture the upper third, and leave the bottom two thirds intact? Enrico Aster (closing): Arterial reconstructions to heavily and circumferentially calcified distal vessels were limited to patients with critical ischemia. The fracture technique was utilized only when no soft arterial segment was found and the artery could not be incised with an ordinary scalpel or Potts scissors. Dr. Fellows, inserting catheters and inflating balloons in diseased arteries for control of back bleeding may be hazardous, especially when one is dealing with small vessels. Dr. Levin, fracturing only a third of the vessel would be very difficult using this technique. I am in the process of developing techniques that utilize ultrasonic principles to facilitate such procedures and to make them less traumatic to the intimal layer.
223