No-reflow phenomenon during percutaneous transluminal coronary angioplasty

Predictors of no- reflow during primary angioplasty for acute myocardial infarction, from Medical College Hospital, Trivandrum

Background

Primary angioplasty (PCI) for acute myocardial infarction is associated with no-reflow phenomenon, in about 5–25% of cases. Here we analysed the factors predicting no reflow .

Methods

This was a case control study of consecutive patients with acute myocardial infarction who underwent Primary PCI from August 2014 to February 2015.

Results

Of 181 patients who underwent primary PCI, 47 (25.9%) showed an angiographic no-reflow phenomenon. The mean age was 59.19 ± 10.25 years and females were 11%.

Univariate predictors of no reflow were age >60 years (OR = 6.146, 95%CI 2.937–12.86, P = 0<0.001), reperfusion time >6 h (OR = 21.94, 95%CI 9.402–51.2, P = < 0.001), low initial TIMI flow (≤1) (OR = 12.12, 95%CI 4.117–35.65, P < 0.001), low initial TMPG flow (≤1) (OR = 36.19, 95%CI 4.847–270.2, P < 0.001) a high thrombus burden (OR = 11.04,95%CI 5.124–23.8, P < 0.001), a long target lesion (OR = 8.54, 95%CI 3.794–19.23, P < 0.001), Killip Class III/IV(OR = 2.937,95%CI 1.112–7.756,P = 0.025) and overlap stenting(OR = 3.733,95%CI 1.186–11.75,P = 0.017).

Multiple stepwise logistic regression analysis predictors were: longer reperfusion time > 6 h (OR = 13.844, 95%CI 3.214–59.636, P = <0.001), age >60 years (OR = 8.886, 95%CI 2.145–36.80, P = 0.003), a long target lesion (OR = 8.637, 95%CI 1.975–37.768, P = 0.004), low initial TIMI flow (≤1) (OR = 20.861, 95%CI 1.739–250.290, P = 0.017).

Conclusions

It is important to minimize trauma to the vessel, avoid repetitive balloon dilatations use direct stenting and use the shortest stent if possible.

Perfusion assessed by real-time contrast echocardiography correlates with clinical and echocardiographic parameters in patients with first STEMI treated with PCI - 6-month follow-up

INTRODUCTION

Angiographic flow in an epicardial artery does not define perfusion at a microvascular level in patients with acute myocardial infarction (AMI). The aim of the study was assessing microvascular reperfusion by myocardial contrast echocardiography (MCE) and left ventricular (LV) functional recovery by echocardiographic methods in patients treated with primary PTCA.

MATERIAL AND METHODS

100 consecutive patients with first ST-elevation AMI with single vessel disease treated successfully with primary PCI were enrolled. Regional contrast score index (RCSI), ejection fraction (EF), wall motion score index (WMSI), and end-systolic and end-diastolic volume (ESV, EDV) were evaluated during hospitalization and at 6-month follow-up. The patients were divided into 2 groups according to the absence (Group 1) or presence (Group 2) of perfusion defects on MCE.

RESULTS

Group 1 had lower WMSI (p = 0.0009), higher EF than Group 2 (44.7 and 55.9% respectively, p = 0.000067), and lower ESV (66.0 and 52.6 ml respectively, p = 0.003185). In Group 1 LVEF increased significantly on 6-month follow-up (p = 0.026), while in Group 2 it decreased (p = 0.0175). Both EDV and ESV were significantly lower in Group 1 (p = 0.0106 and p = 0.002882, respectively). There was a correlation between the presence of perfusion defects in the initial contrast echo and unfavourable change in ejection fraction during the follow-up (ANOVA for repeated measures, F[1.91] = 5.85, p = 0.0175). The combined clinical end-point (death and reinfarction) was significantly lower in patients without perfusion defect (p = 0.039).

CONCLUSIONS

Myocardial contrast echocardiography results correlated with clinical outcome and recovery of systolic left ventricular function at 6-month follow-up.

Myocardial perfusion assessed by contrast echocardiography correlates with angiographic perfusion parameters in patients with a first acute myocardial infarction successfully treated with angioplasty

BACKGROUND

Angiographic flow in an epicardial artery does not define perfusion at the microvascular level.

AIM

To compare myocardial contrast echocardiography (MCE) with angiographic methods of assessing microvascular reperfusion in patients with acute myocardial infarction (AMI).

METHODS

One hundred consecutive patients with a first ST segment elevation myocardial infarction and single-vessel disease were successfully treated with primary percutaneous coronary intervention. Regional contrast score index (RCSI), corrected Thrombolysis In Myocardial Infarction (TIMI) frame count (cTFC), TIMI myocardial perfusion grade (TMPG) and myocardial blush grade were evaluated.

RESULTS

Among 717 asynergic segments on MCE, 168 revealed a lack of perfusion. TMPG and cTFC correlated significantly with RCSI (P=0.031 and P=0.027, respectively). Myocardial blush grade did not correlate with RCSI (P=0.067). Patients with anterior AMI had significantly more segments with a perfusion defect on MCE than patients with inferior AMI (P=0.0001).

CONCLUSIONS

MCE results correlate with angiographic methods of perfusion assessment such as TMPG and cTFC. Anterior AMI is associated with a greater extent of perfusion defect. MCE results correlate also with recovery of systolic left ventricular function and clinical outcome at six month follow-up.

Efficacy of intracoronary nicardipine in the treatment of no-reflow during percutaneous coronary intervention

OBJECTIVES

The goal of this study was to evaluate the safety and efficacy of nicardipine in reversing no-reflow during percutaneous coronary intervention (PCI).

BACKGROUND

No-reflow is a common complication of PCI in patients with acute coronary syndromes or venous bypass graft disease. Although nicardipine has an attractive pharmacological profile and has been used clinically to treat no-reflow, there is a paucity of published data regarding its effectiveness in this setting.

METHODS

We conducted a retrospective analysis of 72 consecutive patients who received intracoronary nicardipine to reverse no-reflow during coronary intervention. Qualitative TIMI flow grade and quantitative TIMI frame count methods were used to assess the efficacy of nicardipine.

RESULTS

A mean of 460 +/- 360 mcg of intracoronary nicardipine was used. No-reflow was successfully reversed with complete restoration of TIMI 3 flow in 71 of 72 patients (98.6%). TIMI flow grade improved from 1.65 +/- 0.53 prior to nicardipine to 2.97 +/- 0.24 after treatment (P < 0.001). TIMI frame count decreased from 57 +/- 40 at the time of no-reflow to 15 +/- 12 after nicardipine administration (P < 0.001). Nicardipine therapy was well tolerated without adverse hemodynamic or chronotropic effects.

CONCLUSIONS

In this largest series to date, intracoronary nicardipine was demonstrated to be a safe and highly effective pharmacological agent to reverse no-reflow during PCI.

Frequency of slow coronary flow following successful stent implantation and effect of Nitroprusside

Nitroprusside (NTP) is used for the treatment of slow coronary flow (SCF) after coronary interventions. The wide variation in dosage, route, and timing of its administration in the reported studies prevents an objective assessment of its efficacy. We report the incidence and response to a standardized NTP protocol of SCF after successful stent implantation. Selective intracoronary administration of incremental doses (initial bolus of 80 microg incremented by 40 microg) of NPT was assessed in 21 patients who developed SCF in a series of 2,212 consecutive patients who underwent successful stent placement from January to October 2005. SCF was observed only in patients treated for acute myocardial infarction (AMI; 11.5%, 12 of 105) or saphenous vein graft (SVG) stenosis (8.2%, 9 of 109). An intracoronary bolus of nitroglycerin did not restore normal Thrombolysis In Myocardial Infarction (TIMI) flow in any patient. The first 80-microg dose of NTP restored normal TIMI flow in 58% of patients (7 of 12) with AMI and in 44% of patients (4 of 9)with SVG stenosis. The maximal dose (120/160 microg) restored normal TIMI flow in all remaining patients with AMI but in only 1 additional patient with SVG stenosis. At the end of the procedure, the percent decrease in corrected TIMI frame count was significantly larger in patients with AMI (-44+/-10%) than in those with SVG stenosis (-24+/-16%, p=0.02). In a large consecutive series of successful stent procedures, SCF was found only in patients with ST-elevation AMI (11.5%) or with a stenosed SVG (8.2%). In conclusion, the standardized protocol of intracoronary NTP administration succeeded in normalizing SCF in all patients with AMI but in only 5 of 9 patients with SVG stenosis. This latter subgroup requires other therapeutic strategies.

Effects of the nitric oxide donor nitroprusside on no-reflow phenomenon during coronary interventions for acute myocardial infarction

We tested the effects of the nitric oxide donor nitroprusside as treatment for no reflow in 23 consecutive patients who underwent coronary angioplasty for acute myocardial infarction. No reflow was defined as a decrease of >/=1 Thrombolysis In Myocardial Infarction (TIMI) trial flow grade occurring after successful initial coronary recanalization. Nitroprusside induced a significant improvement in coronary flow, with an increase in TIMI flow grade from 1.5 +/- 0.8 to 2.9 +/- 0.3 (p <0.0001) and in TIMI frame count from 46 +/- 25 to 16 +/- 5 (p <0.0001). There were no significant adverse effects apart from transient hypotension. Intracoronary nitroprusside should be considered as a treatment of no reflow occurring in acute myocardial infarction.

Mechanical protection of cardiac microcirculation during percutaneous coronary intervention of saphenous vein grafts

Saphenous vein bypass grafts permeability is one of the most important limitations of open heart surgery. The risks associated with surgical re-intervention are greater than those associated with the initial procedure. While native coronary arteries usually have fixed, fibrotic or calcified atherosclerotic plaques, the disease in the vein grafts contains soft material. When this material is compressed during percutaneous angioplasty, there is an unfavorable immediate outcome due to distal embolization of thrombus and plaque debris. In addition, the risk of post-procedure adverse events are higher when the grafts have a long time of implantation, due to a greater risk of branch occlusion or no-reflow at the adjacent microcirculation. The clinical consequence is a Non-Q-Wave Myocardial Infarction that is reflected in the increased serum cardiac enzymes. It is because of this complication that the distal protection devices were developed. The purpose of this paper is to review and discuss the current data on the distal protection devices available now for the treatment of degenerative saphenous vein graft disease. Currently, there are two distal protection devices approved in the United States: the Guardwire Balloon and Aspiration (Export) System and the Filter Wire EX. Other devices like the Triactiv System, Angioguard XP/ECW, DOW, MedNova Cardioshield, Medtronic-AVE DPD and the E-Trap Filter are still being studied. The first observational studies showed the safety and efficacy of the approved devices. A large randomized trial initially confirmed a significant decrease of in-hospital and 30-day cardiac adverse events, mainly Non-Q-Wave Myocardial Infarction, when angioplasty was performed with the assistance of the Guardwire System. Subsequently, another randomized study showed an equivalence between the Guardwire System and the Filter Wire EX. Distal protection devices have an acceptable performance, however, further technological improvements are warranted for a quick preparation, delivery and/or retrieval of these devices.

Resolution of refractory no-reflow with intracoronary epinephrine

Refractory no-reflow is associated with adverse outcomes in patients undergoing percutaneous coronary intervention. Charts were reviewed to identify 29 consecutive patients in whom intracoronary epinephrine was administered for refractory no-reflow. The effects of intracoronary epinephrine on coronary flow (TIMI grade), cardiac rhythm, and systolic blood pressure in the cardiac catheterization laboratory were assessed. Administration of intracoronary epinephrine (mean dose, 139 +/- 189 microg) resulted in significant improvement in coronary flow. After administration, TIMI 3 flow was established in 69% of patients. Overall, TIMI flow significantly increased (mean TIMI flow form 1.0 +/- 1.0 to 2.66 +/- 0.55; P = 0.0001). Intracoronary epinephrine resulted in significant but tolerable increase in heart rate (72 +/- 19 to 86 +/- 26 beats/min; P = 0.009), but no cases of acute dysrhythmia. These findings indicate that intracoronary epinephrine may exert salutary effects in patients suffering refractory no-reflow following elective or acute coronary interventions.

Reversal of slow flow phenomenon during primary stenting by bail-out administration of abciximab

BACKGROUND: Slow flow or no reflow phenomenon is increasingly being recognized as a serious problem during coronary angioplasty and stenting. This phenomenon is seen more often during angioplasty in highly thrombogenic milieux, especially in a setting of acute myocardial infarction. The treatment of this complication is often not satisfactory. In this study the authors assessed the efficacy of abciximab, a potent antiplatelet drug, in treating slow flow or no reflow phenomenon during primary percutaneous transluminal coronary angioplasty (PTCA) for acute myocardial infarction (AMI). METHODS: Twenty-one instances of persistent slow flow phenomenon were encountered in 131 consecutive patients subjected to primary PTCA for AMI (16%). It was more common in patients presenting with AMI complicated by cardiogenic shock (nine of 21, 43%). Of these 21 cases of slow flow, 10 patients were given injection abciximab during the procedure of primary PTCA as a bail-out measure after encountering the complication of slow flow or no reflow. A pre-discharge coronary angiography was carried out in all patients who survived. RESULTS: In seven of 10 patients in the abciximab group flow had improved to TIMI-3. In contrast, in the non-abciximab group TIMI flow improved in only four of 11 patients. Patients with persistent slow flow had significantly higher mortality at the first 30-day follow-up than patients with TIMI-3 flow (33% versus 1.8%, p<0.001). CONCLUSION: In this small nonrandomized study significant improvement in coronary flow was achieved by using intravenous abciximab after observing slow flow or no reflow phenomenon during primary PTCA. More frequent use of this drug in this milieu might help in preventing the development of this complication. Larger studies are warranted to confirm this life-saving beneficial effect of bail-out administration of abciximab during primary angioplasty.

Intracoronary adenosine administered during rotational atherectomy of complex lesions in native coronary arteries reduces the incidence of no-reflow phenomenon

Rotational atherectomy (RA) of complex, calcified lesions has been associated with a high incidence of no reflow ranging from 6%-15% and concomitant myocardial necrosis with adverse prognostic implications. There are no uniform strategies for preventing this complication. The role of intracoronary adenosine for the prevention of this phenomenon during RA has not been fully evaluated. We studied the procedural outcome of 122 patients who underwent RA of complex native coronary artery lesions. Fifty-two patients received no adenosine but a variety of other agents. Seventy patients received intracoronary adenosine boluses (24 to 48 microgram prior to and after each RA run). There was no difference in the type of lesion studied, run time, or Burr to artery ratio (0.6-0.7) between the two groups. Six patients without adenosine experienced no reflow (11.6%), with resultant infarction in the target artery territory, while only 1 of 70 patients (1.4%, P - 0.023) in the adenosine group experienced no reflow. No untoward complications were observed during adenosine infusion. Intracoronary adenosine bolus administered during rotational atherectomy is easy, safe, and may significantly reduce the incidence of no reflow, which may improve the 30-day outcome of this procedure.

The distinction between coronary and myocardial reperfusion after thrombolytic therapy by clinical markers of reperfusion

OBJECTIVES

We sought to examine the hypothesis that rapid resolution of ST-segment elevation in acute myocardial infarction (AMI) patients with early peak creatine kinase (CK) after thrombolytic therapy differentiates among patients with early recanalization between those with and those without adequate tissue (myocardial) reperfusion.

BACKGROUND

Early recanalization of the epicardial infarct-related artery (IRA) during AMI does not ensure adequate reperfusion on the myocardial level. While early peak CK after thrombolysis results from early and abrupt restoration of the coronary flow to the infarcted area, rapid ST-segment resolution, which is another clinical marker of successful reperfusion, reflects changes of the myocardial tissue itself.

METHODS

We compared the clinical and the angiographic results of 162 AMI patients with early peak CK (< or =12 h) after thrombolytic therapy with (group A) and without (group B) concomitant rapid resolution of ST-segment elevation.

RESULTS

Patients in groups A and B had similar patency rates of the IRA on angiography (anterior infarction: 93% vs. 93%; inferior infarction: 89% vs. 77%). Nevertheless, group A versus B patients had lower peak CK (anterior infarction: 1,083+/-585 IU/ml vs. 1,950+/-1,216, p < 0.01; and inferior infarction: 940+/-750 IU/ml vs. 1,350+/-820, p=0.18) and better left ventricular ejection fraction (anterior infarction: 49+/-8, vs. 44+/-8, p < 0.01; inferior infarction: 56+/-12 vs. 51+/-10, p=0.1). In a 2-year follow-up, group A as compared with group B patients had a lower rate of congestive heart failure (1% vs. 13%, p < 0.01) and mortality (2% vs. 13%, p < 0.01).

CONCLUSIONS

Among patients in whom reperfusion appears to have taken place using an early peak CK as a marker, the coexistence of rapid resolution of ST-segment elevation further differentiates among patients with an opened culprit artery between the ones with and without adequate myocardial reperfusion.

The pattern of alteration in flow velocity in the recanalized artery is related to left ventricular recovery in patients with acute infarction and successful direct balloon angioplasty

OBJECTIVES

We evaluated the relationship between alterations in coronary flow velocity during the acute phase of acute myocardial infarction (AMI) and the recovery of left ventricular wall motion in patients who underwent successful primary angioplasty.

BACKGROUND

The status of the coronary microcirculation is the major determinant of the prognosis of patients who have had successful reperfusion after AMI. Animal studies have shown that dynamic changes in regional flow are associated with the extent of infarction. Evaluation of alterations in coronary flow velocity in infarcted arteries may provide information about microcirculatory damage.

METHODS

Flow velocity of the distal anterior descending artery was continuously monitored with the use of a Doppler guide wire immediately after recanalization for 18 +/- 4 h in 19 patients who underwent successful primary angioplasty after anterior AMI. Subjects were divided into two groups on the basis of the time course of alterations in average peak velocity (APV). Group D consisted of patients who had progressive decreases in APV through the next day (n = 9), and Group I comprised patients with an increase in APV after a transient decline (n = 10). Ejection fraction (EF) and regional wall motion (RWM) were assessed by left ventriculography performed on admission and at discharge.

RESULTS

The APV at the end of monitoring was greater in group I than in group D. In group I, EF and RWM were significantly improved at discharge. The change in EF was greater in group I than in group D (17 +/- 9% vs. 4 +/- 9%, p = 0.007), as was the change in RWM (0.96 +/- 0.23 vs. 0.13 +/- 0.36 SD/chord, p < 0.0001).

CONCLUSIONS

The alteration in flow velocity in recanalized infarcted arteries is related to left ventricular recovery. A progressive decrease in velocity after angioplasty implies no reflow, which is associated with a poor recovery of left ventricular function. Reperfusion injury may account in part for this phenomenon.

Rapid reversal of no-reflow using Abciximab after coronary device intervention

The no-reflow phenomenon is a reduction in epicardial coronary artery blood flow without mechanical vessel obstruction. Early descriptions of this syndrome involved reperfusion after myocardial infarction. More recently, the no-reflow phenomenon has been recognized after brief ischemic times associated with coronary interventions. It is clearly a negative prognostic indicator. The proposed mechanism is multi-factorial and may involve small vessel vasospasm and potentially platelet-mediated loss of capillary autoregulation. Because of the potential role of platelets in the genesis of the no-reflow state, we administered Abciximab to two patients with no-reflow phenomenon following catheter interventions. In both of these settings, rapid distal runoff was reestablished within minutes after treatment with the platelet glycoprotein 2B/3A inhibitor.

Attenuation of the no-reflow phenomenon after coronary angioplasty for acute myocardial infarction with intracoronary papaverine

The no-reflow phenomenon is observed as reduction of coronary blood flow on the angiograms (angiographic no-reflow) after immediate percutaneous transluminal coronary angioplasty (PTCA) in patients with acute myocardial infarction (AMI). To assess whether a potent coronary microvascular dilator--papaverine--could attenuate the no-reflow phenomenon, nine patients with AMI who were found to have angiographic no-reflow after PTCA were studied. Angiographic no-reflow was defined as the Thrombolysis in Myocardial Infarction flow grade 1 or 2 without any mechanical obstructions in the epicardial artery. A bolus dose of 10 mg of intracoronary papaverine was administered, and the flow grade was again evaluated. Intracoronary papaverine caused a significant improvement of the flow grade (p= 0.0152). The number of cineframes that were required for the contrast medium to pass two selected landmarks on the angiograms also significantly decreased (41 +/- 17 frames to 18 +/- 8 frames, p= 0.0039). Thus intracoronary papaverine attenuated angiographic no-reflow that occurred after PTCA for AMI.

Distal vessel pullback angiography and pressure gradient measurement: an innovative diagnostic approach to evaluate the no-reflow phenomenon

The angiographic appearance of "no-reflow" in saphenous vein grafts or native coronary arteries has been described following administration of thrombolytic therapy or performance of percutaneous transluminal coronary angioplasty or atherectomy. Apparent occlusion may represent spasm, dissection, thrombosis, or competitive collateral circulation, all of which must be excluded to make the diagnosis of "no-reflow." We describe an innovative approach to the diagnostic dilemma created by the appearance of "no-reflow" at coronary angiography. Pressure gradient measurement with distal vessel pull-back (retrograde) angiography provides maximal information regarding the severity of disease and the etiology of "no-reflow," while exposing both the patient and angiographer to less risk compared to standard strategies.

Clinical significance of no-reflow phenomenon observed on angiography after successful treatment of acute myocardial infarction with percutaneous transluminal coronary angioplasty

The clinical significance of the angiographic no-reflow phenomenon was evaluated in 93 patients with acute myocardial infarction treated by percutaneous transluminal coronary angioplasty (PTCA). On the basis of the post-PTCA angiograms, patients were divided into three groups: normal angiogram (group 1, n = 65), slight no-reflow (group 2, n = 13), and severe no-reflow (group 3, n = 15). Regional wall motion in the chronic phase was depressed in groups 2 and 3 compared with group 1. The proportion of the area of the transmural infarction to that of the total infarction determined by scintigraphy was higher in groups 2 and 3 than in group 1. A significantly higher incidence of myocardial rupture and of death resulting from cardiac causes was observed in group 3 compared with group 1. The severity of this phenomenon immediately after an emergency PTCA correlated well with the severity of myocardial damage, with patients having severe no-reflow showing the poorest prognosis.

Features and outcome of no-reflow after percutaneous coronary intervention

No-reflow is an uncommon complication that may occur after revascularization of patients with acute myocardial infarction, after interventions in saphenous vein bypass grafts, and after the use of some new interventional devices. However, the clinical impact of no-reflow after coronary intervention is unknown. Accordingly, this study examined the incidence, clinical presentation, angiographic characteristics, and outcome of no-reflow after percutaneous coronary intervention. No-reflow was defined as an acute reduction in antegrade flow (< or = 1, as defined by the Thrombolysis in Myocardial Infarction [TIMI] trial) not attributable to abrupt closure, high-grade stenosis, or spasm of the original target lesion. Among 10,676 coronary interventions performed between October 1988 and June 1993, no-reflow occurred in 66 patients (0.6%). These patients were compared with a subgroup of 500 consecutive patients who did not exhibit no-reflow. The incidence of no-reflow was 30 of 9,431 (0.3%) for percutaneous transluminal coronary angioplasty, 1 of 317 (0.3%) for excimer laser, 8 of 104 (7.7%) for Rotablator (Heart Technologies, Bellevue, Washington), 21 of 469 (4.5%) for extraction atherectomy, and 6 of 355 (1.7%) for directional atherectomy. Compared with those without no-reflow, patients with no-reflow experienced a 10-fold higher incidence of in-hospital death (15%) and acute myocardial infarction (31%). Correlates of in-hospital mortality included acute myocardial infarction on presentation (p = 0.006) and final flow < 3 (as defined by the TIMI trial) at completion of the procedure (p = 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

Diffuse embolization following percutaneous transluminal coronary angioplasty of occluded vein grafts: the blush phenomenon

Percutaneous transluminal coronary angioplasty (PTCA) was performed on 146 saphenous vein grafts in 116 patients. In 29 patients, 31 grafts were totally occluded. Myocardial staining lasting over 5 minutes--"the blush phenomenon"--followed the opening of the occluded grafts in 9 of these patients. In 5 of these 9, enzyme release suggested infarction. A sixth patient died within a few hours of PTCA, with suspected infarction. Autopsy demonstrated diffuse and extensive distal coronary arterial embolization of grumous material, including cholesterol crystals, platelets, and fibrin. The blush phenomenon was not seen following PTCA in the remaining 20 patients with total occlusions, nor in any of the 87 patients with stenosed grafts. We have not observed the blush phenomenon following PTCA of more than 3300 coronary arteries. Of the 9 patients demonstrating the blush phenomenon, 6 had a recent history of myocardial infarction or unstable angina pectoris, compared with 4 of the remaining 20 patients with occluded grafts. We now approach occluded grafts with injection of intragraft thrombolytic agents or with atherectomy prior to PTCA. Future approaches may include atherectomy or laser angioplasty.