Elastic recoil following percutaneous transluminal coronary angioplasty and Palmaz-Schatz stent implantation

The post-procedural elastic recoil in 133 lesions treated with the Palmaz-Schatz stent was compared to 133 matched lesions treated with balloon angioplasty to determine the role of prevention of elastic recoil in the creation of a larger initial luminal diameter. Elastic recoil was defined as the difference between the maximal diameter of the inflated balloon and the minimal luminal diameter of the dilated segment immediately after the procedure and was evaluated by quantitative coronary angiography. Overdilatation was defined as a dilatation induced by a balloon with a maximal diameter larger than the pre-procedure reference diameter. The percent diameter stenosis was reduced from 73% to 31% in the balloon angioplasty group and from 72% to -4% in the stent group (31% vs. -4%, p < 0.01). Elastic recoil was significantly larger in the balloon angioplasty group than in the stent group (0.94 +/- 0.29 mm vs. 0.09 +/- 0.09 mm, p < 0.01). Overdilatation and lesion morphology had no significant effects on elastic recoil in the stent group. In the balloon angioplasty group, overdilatation, noncalcified lesions and eccentric lesions were associated with increased elastic recoil. These results indicated that the larger post-procedural luminal diameter associated with the Palmaz-Schatz stent was primarily the result of prevention of elastic recoil, which was not influenced by the degree of overdilatation or lesion morphology.     

Reduction of early elastic recoil by cutting balloon angioplasty as compared to conventional balloon angioplasty

BACKGROUND: Restenosis after successful balloon angioplasty remains problematic. Early elastic response after angioplasty is significant when considering the possible development of restenosis. The purpose of this study was to compare early elastic recoil within 10 minutes after successful percutaneous transluminal coronary angioplasty and early lumen loss at 24 hours after angioplasty in a cutting balloon group and a conventional balloon group. METHODS: Extent of early elastic recoil was quantitatively measured as the difference of mean balloon diameter at maximal inflation pressure and minimal luminal diameter after angioplasty in 82 cutting balloon-treated lesions and 51 conventional balloon-treated lesions. RESULTS: Reference diameter and balloon/artery ratio were similar between the cutting balloon and conventional balloon groups (2.89 0.47 mm vs. 2.88 0.60 mm; 1.19 0.11 vs. 1.19 0.13, respectively). Early elastic recoil after angioplasty was significantly smaller in the cutting balloon than the conventional balloon group (0.96 0.40 mm vs. 1.12 0.37 mm, respectively; p = 0.04). Also, the mean amount of lumen loss from 10 minutes after angioplasty to 24 hours after was significantly smaller in the cutting balloon than the conventional balloon group (0.08 0.28 mm vs. 0.20 0.33 mm, respectively; p = 0.02). CONCLUSION: There is significantly less early elastic recoil in the cutting balloon angioplasty than in the conventional balloon angioplasty group. The efficacy of cutting balloon continues 24 hours after angioplasty.     

Quantitative angiographic assessment of elastic recoil after percutaneous transluminal coronary angioplasty

Little is known about the elastic behavior of the coronary vessel wall directly after percutaneous transluminal coronary angioplasty (PTCA). Minimal luminal cross-sectional areas of 151 successfully dilated lesions were studied in 136 patients during balloon inflation and directly after withdrawal of the balloon. The circumvent geometric assumptions about the shape of the stenosis after PTCA, a videodensitometric analysis technique was used for the assessment of vascular cross-sectional areas. Elastic recoil was defined as the difference between balloon cross-sectional area of the largest balloon used at the highest pressure and minimal luminal cross-sectional area after PTCA. Mean balloon cross-sectional area was 5.2 +/- 1.6 mm2 with a mean minimal cross-sectional area of 2.8 +/- 1.4 mm2 immediately after inflation. Oversizing of the balloon (balloon artery ratio greater than 1) led to more recoil (0.8 +/- 0.3 vs 0.6 +/- 0.3 mm, p less than 0.001), suggestive of an elastic phenomenon. A difference in recoil of the 3 main coronary branches was observed: left anterior descending artery 2.7 +/- 1.3 mm2, circumflex artery 2.3 +/- 1.2 mm2 and right coronary artery 1.9 +/- 1.5 mm2 (p less than 0.025). The difference was still statistically significant if adjusted for reference area. Thus, nearly 50% of the theoretically achievable cross-sectional area (i.e., balloon cross-sectional area) is lost shortly after balloon deflation.     

Laser balloon angioplasty: clinical, angiographic and histologic results

Laser balloon angioplasty combines conventional coronary angioplasty with laser energy to transiently heat vascular tissue. Laser balloon angioplasty, was performed in 21 patients (aged 56 +/- 13 years), including 10 patients treated urgently after acute failure of conventional angioplasty and 11 patients treated with elective laser balloon angioplasty. Immediately after conventional angioplasty, laser doses (1 to 10 doses of 205 to 380 J each) were delivered during inflation of the laser balloon to a pressure of 4 atm. Seven (70%) of 10 patients with acute failure of conventional angioplasty were successfully treated with laser balloon angioplasty, but 3 (30%) were unsuccessfully treated with the laser procedure and required emergency coronary artery bypass surgery. In all three failures, the 3 mm laser balloon angioplasty catheter was not the optimal size for the vessel. In the 11 patients treated with elective laser balloon angioplasty (reference diameter 2.94 +/- 0.22 mm), the minimal luminal diameter increased from 0.45 +/- 0.25 to 1.85 +/- 0.46 mm after conventional angioplasty and to 2.44 +/- 0.29 mm after laser balloon angioplasty (p less than 0.001). This corresponded to a decrease in diameter stenosis from 84 +/- 9% before to 35 +/- 16% after conventional angioplasty and to 15 +/- 10% after laser balloon angioplasty (p less than 0.001). There were no instances of myocardial infarction, emergency coronary artery bypass surgery or death and no acute complications related to delivery of laser energy in this group. Follow-up coronary angiography was performed 5.5 +/- 1.1 months after laser balloon angioplasty in 18 patients discharged from the hospital after a successful procedure. Ten patients (56%) had angiographic restenosis, defined as recurrent diameter stenosis greater than 50%. Six patients were subsequently treated by directional coronary atherectomy, which revealed intimal proliferation indistinguishable from that in patients with restenosis after conventional angioplasty. In conclusion, laser balloon angioplasty may be effective in sealing severe coronary dissections and reversing abrupt closure associated with failed conventional angioplasty. After uncomplicated conventional angioplasty, laser balloon angioplasty improves immediate luminal dimensions, but restenosis appears to be mediated by intimal hyperplasia, similar to that seen after conventional angioplasty.     

Angiographic and histologic consequences of laser thermal angioplasty: comparison with balloon angioplasty

The angiographic and histologic consequences of laser thermal angioplasty were examined and compared with those of conventional balloon angioplasty in an atherosclerotic rabbit iliac artery preparation immediately and 4 weeks after the procedure. Nineteen vessels in 13 rabbits underwent either laser thermal or balloon angioplasty in random order. Laser thermal angioplasty was performed in a total of nine vessels with either a 1.5 or 2.0 mm laser-heated metallic-capped fiber by delivery of 6 or 8 W, respectively, of argon laser energy for 5 sec duration during continuous advancement through the stenosis. Balloon angioplasty was performed in a total of 10 stenotic lesions with a 2.5 mm balloon catheter. The immediate enlargement of the angiographic luminal diameters was similar for both procedures: from 1.0 +/- 0.2 to 1.9 +/- 0.2 mm for laser thermal angioplasty vs 1.0 +/- 0.1 to 2.0 +/- 0.2 mm for balloon angioplasty. However, 4 weeks later the vessels treated with laser thermal angioplasty had less restenosis, defined as a 20% or greater reduction in luminal diameter (two of nine vessels [22%] vs 10 of 10 vessels [100%]; p less than .001), and a significantly larger mean luminal diameter (1.6 +/- 0.5 vs 1.0 +/- 0.4 mm) than those treated with conventional balloon angioplasty (p less than .02). Histologic examination 4 weeks after the procedure revealed less fibrocellular proliferation after laser thermal angioplasty, whereas those vessels treated with balloon angioplasty demonstrated evidence of prior fracture and dissection of the vessel wall with more of a fibrocellular proliferative response.(ABSTRACT TRUNCATED AT 250 WORDS)     

Applicability of laser to assist coronary balloon angioplasty

Severe atherosclerotic obstructed coronary artery disease (CAD) may preclude passage of a balloon catheter for transluminal coronary angioplasty (TCA). Since lasers have been shown to effectively vaporize CAD plaque, the initial application of laser to effect a lumen large enough to accommodate the angioplasty catheter for further dilatation was explored. Eleven postmortem human CAD segments which did not permit passage of a 1.33 mm shaft diameter angioplasty catheter were studied. Argon laser radiation (14 to 90 J) transmitted via 400 micron core diameter quartz fiber onto the stenotic channel of 0.58 mm created a vaporized lumen of 1.77 mm (mean increase of 1.31 +/- 0.25 mm, p less than 0.001). The laser procedure allowed the balloon angioplasty catheter to be pushed into the stenosis. TCA was then performed (7 atm, 45 seconds) and expanded the channel to 2.12 mm (additional mean increase of 0.38 +/- 0.07 mm, p less than 0.001). In terms of percent luminal narrowing, laser radiation reduced obstruction from 80% to 45% (mean difference of -38.7 +/- 4.6%, p less than 0.001), and TCA caused a further decrease to 37% (mean difference of -9.3 +/- 1.9%, p less than 0.001). Thus, in tight atherosclerotic lesions, the laser may be useful in creating an initial opening enabling the placement of the balloon angioplasty catheter which, in turn, can further dilate the lased stenotic coronary lumen.     

Efficacy of a new angioplasty catheter for severely narrowed coronary lesions

Conventional over the wire dilation catheters may be unsuccessful in crossing coronary lesions that are severely narrowed. Hence, a new, extremely low profile coronary angioplasty catheter specifically designed to dilate such lesions was investigated. The catheter features a 2.0, 2.5 or 3.0 mm (inflated diameter) balloon mounted on a guide wire. The deflated profile of the 2.0 mm balloon measures 0.020 +/- 0.001 in. (0.51 +/- 0.03 mm). The catheter can be used in conjunction with 7F angiographic or 8F guide catheters. The catheter was used in 61 patients, aged 43 to 86 years, with predominantly Canadian Cardiovascular Society class III-IV angina. Dilation was attempted in 77 lesions. Lesion length averaged 5.7 +/- 3.1 mm (mean +/- 1 SD), minimal diameter 0.51 +/- 0.25 mm and internal vessel diameter 2.27 +/- 0.43 mm. Sixty lesions (78%) were successfully dilated to less than 50% residual stenosis with this catheter alone; nine lesions were further dilated with a larger balloon catheter. The new catheter was unable to cross 13 lesions (17%); only 2 of these lesions were subsequently crossed with a conventional over the wire system. On the other hand, the catheter was used after failure of conventional dilating catheters in 21 lesions and was successful in 16. The new catheter was particularly valuable for distal lesions and those demonstrating 90 to 99% diameter reduction. For all lesions crossed, stenosis decreased from 76 +/- 11 to 29 +/- 12% after 2.9 +/- 2.7 inflations and peak inflation pressure of 8.0 +/- 2.9 bar. Complications were rare; coronary occlusion occurred in two lesions (3%) and dissection in three lesions (4%).(ABSTRACT TRUNCATED AT 250 WORDS)     

The Falconª Eccentric Coronary Balloon Angioplasty Catheter: A Randomized Safety and Efficacy Study

Percutaneous coronary angioplasty (PTCA) is usually performed using concentric shaped balloon catheters with the guidewire passing through the center of the shaft. The Falcona balloon catheter features a guide wire lumen on the outside of the balloon so that an eccentric balloon catheter profile is obtained concentrating the dilating force on the wire supported side, allowing lower inflation pressures and potentially causing less vessel injury. The aim of this study was to evaluate the safety and efficacy of this new balloon catheter in patients with stable and unstable angina. In 95 prospectively randomized patients, 57 lesions were dilated with a concentric balloon and 51 with the eccentric balloon. Technical success in the two groups was similar (73.3% vs. 74.5% control vs. Falcon respectively). Procedural success was 96.5% vs. 96.1% in the control and Falcon groups respectively. The mean increase in minimum luminal diameter (MLD) was 1.01 +/- 0.41 mm in the control vs 0.85 +/- 0.45 mm in Falcon (p = 0.053). There was an increase in type A dissections in the Falcon group 18 (36.75%) vs. 10 (19.23%) in the control group (p = 0.07) with no difference in stent implantation, myocardial infarction, CABG or death between the two groups. All patients with a technically successful PTCA were followed up. Seventeen (43.6%) in the control and 11 (32.4%) in the Falcon had repeat coronary angiography (p = 0.38), 12 (30.8%) vs. 7 (20.6%) had repeat PTCA (p = 0.37) and time to PTCA was 116 +/- 70 days vs. 154 +/- 103 days respectively (p = 0.36). The Falcon performed technically as well as the concentric balloons. Despite a smaller MLD and increase in Type A dissections there was no associated increase in complications or reintervention for restenosis. Further investigation is required to evaluate the role of this mechanism of dilatation in restenosis.     

Angiographic patterns of balloon inflation during percutaneous transluminal coronary angioplasty: role of pressure-diameter curves in studying distensibility and elasticity of the stenotic lesion and the mechanism of dilation

There are few in vivo data concerning the mechanisms of balloon inflation during coronary angioplasty. To characterize how lesions dilate, videodensitometry was used to measure the diameter of the inflated balloon across 29 coronary lesions in 27 patients. Pressure-diameter curves for each lesion were derived with use of a standardized incremental inflation protocol in which pressures between 2 and 6 atm in 3 mm low profile balloons approximated normal vessel diameter. The diameter of coronary stenosis before and after angioplasty was also measured. Pressure-diameter curves showed that the most improvement in luminal caliber occurred at low inflation pressure. A distensibility factor was defined as the ratio of the amount of balloon inflation at 2 atm compared with the balloon diameter at 6 atm. Eccentric irregular lesions (n = 11) had a greater distensibility factor (0.49 +/- 0.17) than did lesions (n = 18) without this configuration (0.33 +/- 0.14) (p less than 0.02). The former were soft, presumably because of thrombus in these lesions. In addition, there were no differences in patterns of balloon inflation for lesions requiring additional inflation or for dilations resulting in an intimal crack or dissection after angioplasty. There was often a loss of luminal caliber when balloon diameter at 6 atm was compared with the diameter after angioplasty. This was defined as elasticity or recoil. There was a significant direct correlation between the amount of elasticity and the extent of balloon inflation at 6 atm (that is, lesions more fully dilated at 6 atm showed more elasticity).(ABSTRACT TRUNCATED AT 250 WORDS)     

Importance of balloon size in coronary angioplasty

The effect of balloon size on the success of coronary angioplasty was studied to develop quantitative criteria for optimal selection of balloon size. Coronary dimensions of 165 stenotic lesions were measured by computer-assisted cinevideodensitometry in 120 patients who had undergone angioplasty with a balloon selected by visual estimates. Cross-sectional areas and diameters of normal and stenotic arterial segments were measured before and after angioplasty by a previously validated cinevideodensitometric technique. The diameter of the inflated balloon compared with that of the normal arterial segment was expressed as a ratio for sizing balloons. Oversized balloons with a ratio greater than 1.3 (n = 35) caused a high (37%) incidence of dissection, with three severely compromised arterial lumens. Undersized balloons with a ratio less than 0.9 (n = 29) often resulted in significant (greater than 50% diameter stenosis) residual stenotic lesions (21%) and a significantly (p less than 0.05) higher rate of repeat angioplasty for restenosis. Selection of balloon sizes with ratios in the 0.9 to 1.3 range (n = 101) resulted in a low (4%) incidence of dissection with few patients (3%) having significant residual stenosis. Mean residual stenosis (percent diameter reduction) was most severe for undersized (35.0 +/- 18%) or oversized (23.1 +/- 19%) balloons and least severe for balloons with a ratio of 0.9 to 1.3 (18.7 +/- 14%) (p less than 0.001). Repeat angioplasty for restenosis was more frequently required (p less than 0.05) for lesions dilated with undersized balloons. Thus, selection of angioplasty balloons that approximate or slightly exceed the diameter of the normal arterial diameter yields optimal angiographic results with minimal dissections and minimal residual stenotic lesions.     

Coronary vessel stent implantation in patients with symptomatic dissections following balloon dilatation

Dissections after coronary balloon angioplasty are risk factors for acute or subacute vessel closure. Intracoronary stenting was developed to avoid this complication by wrapping the intimal and medial flaps against the vessel wall, which reduces the risk of acute thrombosis. A total of 17 stents were implanted into the coronary arteries of 10 patients with angiographically documented dissections after balloon angioplasty, who presented angina and ischemic ECG changes. Mean minimal stenosis diameter was 1.11 +/- 0.35 mm (65.1%) before, and 1.48 +/- 0.56 mm (53.9%, n.s.) and 2.45 +/- 0.62 mm (23.5%, p less than 0.005), respectively, after balloon angioplasty with and without taking the dissection membrane into account. All patients reported an immediate recovery of their anginal complaints after stent delivery, and ischemic ECG changes disappeared. The mean residual stenosis after coronary stenting was measured as 3.33 +/- 0.23 mm (0%, p less than 0.001). The immediate control angiograms and these after 24 h depicted smooth vessel walls without any irregulations at the site of implantation, and the mean residual stenosis diameter remained unchanged after 24 h (3.3 +/- 0.23 mm; 1.2%, p less than 0.001). No patient suffered acute myocardial infarction, one patient underwent coronary bypass surgery because of persisting episodes of angina pectoris. Thus, intracoronary stenting seems to be a secure and effective method to handle dissections after balloon angioplasty, and perhaps reduces the rate of acute complications and the need for emergency bypass surgery after coronary balloon angioplasty.     

Comparison of Angiographic and Clinical Outcome After Cutting Balloon and Conventional Balloon Angioplasty in Vessels Smaller than 3 mm in Diameter: A Randomized Trial

OBJECTIVES: The purpose of the study was to evaluate and compare the immediate and six month follow-up angiographic and clinical outcome of cutting balloon angioplasty and conventional balloon angioplasty in small vessels (less than 3 mm in diameter). METHODS AND RESULTS: Between August 1995 and August 1996 a total of 71 eligible symptomatic patients with angiographically proven significant lesions in their coronary arteries smaller than 3 mm and requiring revascularization, were randomized to receive treatment by either cutting balloon angioplasty (CB) or conventional balloon angioplasty (BA). òStand-aloneó CB was performed on 51 lesions in 36 patients and BA on 47 lesions in 35 patients. Basic angiographic and clinical characteristics were similar in both groups. The overall procedural success rates for CB and BA groups were 92% and 97%, respectively. The immediate post-procedural minimal luminal diameter, residual stenosis and acute gain were similar in the CB and BA cohorts (1.93 +/- 0.36 mm, 24 +/- 12%, 1.18 +/- 0.45 mm vs. 2.01 +/- 0.34 mm, 22 +/- 9%, 1.26 +/- 0.35 mm, respectively). Total dissection rate and C-F dissections were fewer in the CB group (37%, 6% vs. 51%, 19%, respectively, p < 0.05). Six month follow-up angiographic restenosis rate was lower in the CB group (27% vs. 47%, p < 0.05). We also detected a significant difference of total number of all events at nine month clinical follow up (28% vs. 51%, p < 0.05). CONCLUSION: CB angioplasty can be performed with a comparable success rate to conventional BA in small vessels. Fewer bail-out procedures are needed as CB causes fewer and less severe dissections. There is also a significant reduction in six month restenosis rate. We suggest that CB might be a better option for revascularizing vessels smaller than 3 mm in diameter which are inherently more prone to immediate complications and late restenosis with BA.     

Percutaneous coronary laser balloon angioplasty: initial results of a multicenter experience

A multicenter clinical trial was initiated to test the potential safety and short-term efficacy of a percutaneous coronary application of laser balloon angioplasty, which has been shown experimentally to alleviate the common causes (dissection, recoil, thrombus) of suboptimal luminal results of conventional balloon angioplasty. Fifty-five patients, the majority (62%) of whom had relatively high risk lesions, were treated in 10 centers with a laser balloon that was identical in size (3 x 20 mm) to a balloon used for conventional balloon angioplasty performed on the same lesion immediately before laser balloon angioplasty. One or more neodymium:yttrium aluminum garnet (Nd:YAG) (1,060 nm) laser doses of 250 to 450 J were each delivered over a 20 s duration per exposure. Immediately and 1 day after laser balloon angioplasty no significant adverse effects on the arterial lumen were noted in any patient. By computerized image analysis of cineangiograms initial conventional balloon angioplasty failed to achieve a minimal luminal diameter greater than 1.5 mm in 14 patients (25%), including 3 patients with acute closure. However, after subsequent laser balloon angioplasty, minimal luminal diameter exceeded this value in all patients including this subgroup. Overall, minimal luminal diameter increased from 1.74 +/- 0.46 mm after conventional balloon angioplasty to 2.32 +/- 0.31 mm after laser balloon angioplasty (p less than 0.001) with no change found on 1 day and 1 month follow-up angiograms. Thus, laser balloon angioplasty is a safe, effective procedure for improving luminal dimensions after conventional balloon angioplasty.     

Percutaneous coronary excimer laser-assisted balloon angioplasty: initial clinical and quantitative angiographic results in 50 patients

The initial clinical experience and quantitative angiographic results of percutaneous coronary excimer laser-assisted balloon angioplasty are described for 55 lesions in 50 patients. With use of a xenon chloride (308 nm) excimer laser generator and 1.5 to 1.75 mm catheters, excimer laser angioplasty was attempted at 135 ns pulse width, 25 to 40 Hz repetition rate, 2 to 5 s laser delivery time and 30 to 60 mJ/mm2 energy fluence. Laser success (greater than 20% reduction in absolute percent diameter stenosis) was achieved in 41 (75%) of 55 lesions, with 100% subsequent balloon angioplasty success (less than 50% residual stenosis). By quantitative digital caliper technique, the percent diameter stenosis (mean +/- SE) was reduced from 81 +/- 1% to 50 +/- 3% after excimer laser angioplasty (p less than 0.001) and to 20 +/- 1% after balloon angioplasty (p less than 0.001); minimal luminal diameter increased from 0.56 +/- 0.04 to 1.46 +/- 0.08 mm (p less than 0.001) and 2.03 +/- 0.07 mm (p less than 0.001), respectively. By videodensitometric techniques, the percent area stenosis decreased from 86 +/- 2% to 54 +/- 3% after excimer angioplasty (p less than 0.001) and to 26 +/- 3% after balloon angioplasty (p less than 0.001). There were no perforations, need for emergency bypass surgery or deaths. The overall incidence of abrupt closure (3.6%), dissection (1.8%), embolization (1.8%), filling defect (6%), myocardial infarction (5.5%), side branch occlusion (3.6%) or spasm (3.6%) was infrequent and more related to subsequent balloon angioplasty than to the laser procedure.(ABSTRACT TRUNCATED AT 250 WORDS)     

Trapidil in preventing restenosis after balloon angioplasty in the atherosclerotic rabbit

Trapidil (triazolopyrimidine) possesses activity against platelet-derived growth factor-induced cellular proliferation in vitro and intimal proliferation in vivo. The objective of this study was to determine if trapidil could prevent restenosis in experimentally induced atherosclerotic rabbits. New Zealand White rabbits with preexisting iliac arterial lesions induced by balloon deendothelialization underwent balloon angioplasty. Arteriography was performed before, immediately after, and 4 weeks after the balloon dilatation. Tissue sections of the dilated arterial segment were also analyzed morphometrically. Seventeen rabbits were randomized to two groups: a control group (n = 8) and a trapidil-treated group (n = 9). The treatment group received 30 mg/kg s.c. trapidil twice daily. The angiographic luminal diameters before and after dilatation were similar. At the 4-week restudy, there was a significant preservation of luminal diameter in the trapidil group compared with the control group (1.27 +/- 0.20 vs. 0.94 +/- 0.48 mm, respectively; p less than 0.005). When luminal diameters immediately after dilatation were compared with diameters at the 4-week restudy (i.e., when the degree of restenosis was assessed), there was a greater luminal diameter reduction in the control group than in the trapidil group (0.70 +/- 0.44 vs. 0.30 +/- 0.25 mm, respectively; p = 0.005). By morphometric analyses, the luminal areas were also greater in the trapidil group than the control group (0.80 +/- 0.25 vs. 0.57 +/- 0.33 mm2, respectively; p = 0.03). Intimal thickness was significantly less for the trapidil group than for the control group (0.33 +/- 0.15 vs. 0.44 +/- 0.15 mm, respectively; p = 0.01), as well as medial thickness (0.09 +/- 0.03 vs. 0.11 +/- 0.03 mm, respectively; p = 0.01). In this study, trapidil significantly increased the luminal area and reduced the intimal thickness in the atherosclerotic rabbit iliac artery after balloon angioplasty.     

Percutaneous transluminal coronary angioplasty for restenosis following Palmaz-Schatz stenting: larger size balloons are more effective?]

Intracoronary stenting reduces the restenosis rate after percutaneous transluminal coronary angioplasty (PTCA). However, restenosis still occurs in 20% to 30% of patients after stenting. Management of in-stent restenosis has become a significant challenge in interventional cardiology. The efficacy of re-PTCA with a larger balloon was investigated for restenosis following Palmaz-Schatz stenting. Clinical and angiographic results were compared in 46 consecutive patients with in-stent restenosis after one Palmaz-Schatz stenting. Twenty patients underwent redilation with a slightly larger balloon than used at the stenting (Large group) and 26 underwent redilation with the same size balloon as at the stenting (Control group). The clinical factors, lesion characteristics, lesion length, reference diameter and minimal luminal diameter at re-PTCA for the in-stent restenosis did not differ significantly between the 2 groups. Minimal luminal diameter of the Large group after re-PTCA was significantly larger than that of the Control group (3.1 +/- 0.2 vs 2.9 +/- 1.2 mm, p < 0.05). Follow-up angiography showed that the minimal luminal diameter of the Large group was significantly larger (2.1 +/- 0.6 vs 1.7 +/- 0.6 mm, p < 0.05) and the re-restenosis rate of Large group tended to be lower than that of the Control group (15% vs 38%, p = 0.07). Re-PTCA for in-stent restenosis with a slightly larger balloon than used at the stenting reduces the re-restenosis rate.     

Influence of inflation pressure and balloon size on the development of intimal hyperplasia after balloon angioplasty. A study in the atherosclerotic rabbit

To evaluate the effect of balloon size and inflation pressure on acute and subsequent outcome following balloon angioplasty (BA), 70 New Zealand White rabbits with bilateral femoral atherosclerosis were assigned to four groups: group 1, oversized balloon, low inflation pressure (n = 35 vessels; balloon size, 3.0 mm/inflation pressure, 5 atm); group 2, oversized balloon, high inflation pressure (n = 36; 3.0 mm/10 atm); group 3, appropriate size, low inflation pressure (n = 17; 2.5 mm/5 atm); and group 4, appropriate size balloon, high inflation pressure (n = 19; 2.5 mm/10 atm). Angiograms were obtained before, 10 minutes after, and 28 days after BA and read by two blinded observers using electronic calipers. The in vivo balloon-to-vessel ratio was measured for each group. There were eight non-BA controls. Rabbits were sacrificed either immediately (n = 34) or at 28 days after BA (n = 36), with the femoral vessels pressure perfused for histologic and morphometric analysis. The latter was performed at 28 days only. Absolute angiographic diameters increased in all groups immediately after BA (p less than 0.01). Acute angiographic success, defined as greater than 20% increase in luminal diameter, was higher using high inflation pressure (group 2, 32/36 [89%] and group 4, 16/19 [84%] vs. group 1, 23/35 [66%] and group 3, 9/17 [53%]; p less than 0.05). A 3.0-mm balloon resulted in significant oversizing irrespective of inflation pressure (balloon-to-vessel ratio, 1.5 +/- 0.1 vs. 1.1 +/- 0.1 to 1, for the 2.5-mm balloon). Vessels exposed to high inflation pressure had a significantly higher incidence of mural thrombus, dissection (p less than 0.01), and medial necrosis versus low pressure (p less than 0.05). At 28 days, the rates of restenosis (defined as greater than 50% loss of initial gain) were 14/20 (70%), 11/16 (69%), 5/10 (50%), and 5/10 (50%) for groups 1 through 4 (p = NS; a trend in favor of the groups using an oversized balloon). There was an increase in the degree of intimal hyperplasia by morphometric analysis in all groups, being most marked in group 2 (oversized balloon and high inflation pressure, 1.7 +/- 0.9 vs. 0.5 +/- 0.2 mm for controls, p less than 0.001). We reached two conclusions. First, all protocols resulted in a significant increase in luminal diameter immediately after angioplasty with the highest success rate in vessels subjected to high pressure dilatation.(ABSTRACT TRUNCATED AT 400 WORDS)     

Transluminal coronary angioplasty of postmortem human hearts

Twelve autopsy human hearts were submitted to coronary angiography and coronary arterial balloon angioplasty. The effect of angioplasty was determined by follow-up coronary angiography as well as gross and microscopic inspection of the coronary arteries dilated. Fifty-four dilations were performed in 24 coronary arteries. Angiographically 50 of the 54 dilations resulted in a mean (± standard deviation) increase in luminal diameter ranging from 1.9 ± 0.9 to 2.7 ± 0.8 mm. Failure to increase luminal size was usually related to a predilation coronary diameter greater than that of the inflated angioplasty balloon.

Dilation resulted in mural disruption with intimai or medial tears, or both, in 65 percent of arteries dilated. Disruption was more frequent in arteries with atherosclerosis and calcification. The mechanism of luminal enlargement in coronary angioplasty may be focal damage to the arterial wall with intimai or medial splitting as opposed to plaque compression as initially suggested.     

Lumen narrowing after percutaneous transluminal coronary balloon angioplasty follows a near gaussian distribution: a quantitative angiographic study in 1,445 successfully dilated lesions.

To determine whether significant angiographic narrowing and restenosis after successful coronary balloon angioplasty is a specific disease entity occurring in a subset of dilated lesions or whether it is the tail end of a gaussian distributed phenomenon, 1,445 successfully dilated lesions were studied before and after coronary angioplasty and at 6-month follow-up study. The original cohort consisted of 1,353 patients of whom 1,232 underwent repeat angiography with quantitative analysis (follow-up rate 91.2%). Quantitative angiography was carried out off-line in a central core laboratory with an automated edge detection technique. Analyses were performed by analysts not involved with patient care. Distributions of minimal lumen diameter before angioplasty (1.03 +/- 0.37 mm), after angioplasty (1.78 +/- 0.36 mm) and at 6-month follow-up study (1.50 +/- 0.57 mm) as well as the percent diameter stenosis at 6-month follow-up study (44 +/- 19%) were assessed. The change in minimal lumen diameter from the post-angioplasty angiogram to the follow-up angiogram was also determined (-0.28 +/- 0.52 mm). Seventy lesions progressed toward total occlusion at follow-up. All observed distributions approximately followed a normal or gaussian distribution. Therefore, restenosis can be viewed as the tail end of an approximately gaussian distributed phenomenon, with some lesions crossing a more or less arbitrary cutoff point, rather than as a separate disease entity occurring in some lesions but not in others.     

Restenosis following placement of an intracoronary heparin treated tantulum stent in the hyperlipidemic miniature swine model

Restenosis persists as an important factor limiting a favorable long term outcome following mechanical revascularization. The objective of the present study was to compare the effects of an intracoronary heparin treated tantalum prototype stent and balloon angioplasty on intimal hyperplasia, luminal diameter, and thrombosis in a porcine restenosis model. Male miniswine maintained on a high cholesterol diet and 325 mg aspirin per day underwent cardiac catheterization and oversized balloon injury to the right and left circumflex coronary arteries. Two weeks later one artery was either balloon injured again or implanted with a stent. No additional anticoagulation following stent placement was given, however aspirin was continued throughout the study. At four weeks, the coronary arteries were harvested and prepared for histologic examination and blinded quantitative morphometric analysis. The prototype stent was successfully deployed in 10 coronary arteries. Histological examination at explant revealed no evidence for thrombus or platelet aggregation. The angiographic luminal diameter of stented vessels was not significantly different from the diameter measured prior to implantation. In contrast, the angiographic diameter of balloon injured vessels was significantly decreased (4.4 +/- 0.4 mm2, balloon injured, vs. 5.8 +/- 3.3 mm2, control; p < 0.05). Stented arteries showed significantly more intimal hyperplasia, compared to balloon injured vessels (2.99 +/- 0.58 mm2 intimal area, stented arteries vs. 0.38 +/- 0.15 mm2 intimal area, control arteries; p < 0.05). In conclusion, heparin treated tantalum wire prototype intracoronary stents were successfully deployed in swine coronary arteries with no evidence for thrombus formation. Despite a significant intimal response, luminal diameter was preserved in stented vessels. The data suggest that a heparin treated tantalum wire prototype intracoronary stent may be an effective method of coronary revascularization that results in the preservation of luminal diameter without thrombotic occlusion.