Morphologic observations after percutaneous transluminal balloon angioplasty of early and late aortocoronary saphenous vein bypass grafts

Impact of lesion location on intravascular ultrasound findings and short-term and five-year long-term clinical outcome after percutaneous coronary intervention for saphenous vein graft lesions

BACKGROUND

Little is known about intravascular ultrasound (IVUS) findings and acute post-percutaneous coronary intervention (PCI) outcome and long-term clinical outcome between aorto-ostial lesion and shaft lesion after PCI for saphenous vein graft (SVG) lesions.

METHODS

Aorto-ostial lesion was defined as those arising within 3mm of the origin of SVG and shaft lesion was defined as those arising in remaining portion of SVG. We evaluated pre- and post-PCI IVUS images of 311 SVG lesions and compared IVUS findings and acute post-PCI outcome and 5-year clinical outcome between aorto-ostial lesion (n=64) and shaft lesion (n=247).

RESULTS

The presence of positive remodeling (40% vs. 22%, p=0.026), hypoechoic plaque (47% vs. 36%, p=0.035), plaque rupture (23% vs. 8%, p=0.008), multiple plaque rupture (9% vs. 2%, p=0.038), and an intraluminal mass (54% vs. 25%, p<0.001) were significantly more common in shaft lesion than in aorto-ostial lesion. Post-PCI no-reflow (15% vs. 5%, p=0.033), post-PCI tissue prolapse (TP) (40% vs. 23%, p=0.014), and post-PCI creatine kinase-MB elevation more than 3 times normal (14% vs. 8%, p=0.047) were observed more frequently after PCI for shaft lesion than for aorto-ostial lesion. At 5-year clinical follow-up, the incidences of death (25% vs. 13%, p=0.036) and myocardial infarction (24% vs. 11%, p=0.028), but not the rate of target vessel revascularization (36% vs. 25%, p=0.096), were significantly higher in patients with shaft lesion compared with those with aorto-ostial lesion.

CONCLUSIONS

SVG shaft lesion has more unstable plaque morphology and this may contribute to the worse acute PCI outcomes and long-term outcomes.

Intravascular ultrasound findings that are predictive of no reflow after percutaneous coronary intervention for saphenous vein graft disease

The aim of this study was to investigate the relation between intravascular ultrasound (IVUS) findings and the no-reflow phenomenon and long-term outcome after percutaneous coronary intervention (PCI) of saphenous vein graft (SVG) lesions. No reflow was defined as Thrombolysis In Myocardial Infarction grade 0, 1, or 2 flow after PCI. Of 311 patients who underwent IVUS before and after stenting, no reflow was observed in 39 patients (13%). Degenerated SVG (62% vs 36%, p = 0.002), IVUS-detected intraluminal mass (82% vs 43%, p <0.001), culprit lesion multiple plaque ruptures (23% vs 6%, p <0.001), and tissue prolapse (51% vs 35%, p = 0.043) were observed more frequently in patients with no reflow. In multivariate logistic regression analysis, an intraluminal mass (odds ratio [OR] 4.84, 95% confidence interval [CI] 1.98 to 10.49, p = 0.001), culprit lesion multiple plaque ruptures (OR 3.46, 95% CI 1.46 to 8.41, p = 0.014), and degenerated SVGs (OR 3.17, 95% CI 1.17 to 6.56, p = 0.024) were the independent predictors of no reflow after PCI. At 5-year clinical follow-up, rates of death (14, 36%, vs 55, 20%, p = 0.036) and myocardial infarction (13, 33%, vs 52, 19%, p = 0.039) were significantly higher in the no-reflow group. However, rate of target vessel revascularization was not significantly different between the 2 groups (15, 38%, vs 90, 33%, p = 0.3). IVUS-detected intraluminal mass, multiple plaque ruptures, and degenerated SVGs were associated with no reflow in SVG lesions after PCI. In conclusion, no reflow was associated with poor long-term clinical outcomes after PCI for SVG lesions.

Outcome of undersized drug-eluting stents for percutaneous coronary intervention of saphenous vein graft lesions

We sought to determine the outcome with undersized drug-eluting stents for percutaneous coronary intervention of saphenous vein graft lesions. Using intravascular ultrasound guidance, 209 saphenous vein graft lesions were treated with drug-eluting stents (153 sirolimus-eluting and 56 paclitaxel-eluting stents). The lesions were divided into 3 groups according to the ratio of the stent diameter to the average intravascular ultrasound reference lumen diameter: group I, <0.89; group II, 0.9 to 1.0; and group III, >1.0. Angiographic no-reflow was defined as a Thrombolysis In Myocardial Infarction flow grade of 0, 1, and 2 after percutaneous coronary intervention. Plaque intrusion was defined as tissue extrusion through the stent struts. Stent malapposition was defined as one or more stent struts that had clearly separated from the vessel wall with evidence of blood speckles behind the strut. No significant differences were found in the use of distal protection devices (group I, 44%; group II, 35%; and group III, 36%; p = 0.5); and no significant differences were found in the incidence of stent malapposition among the 3 groups (group I, 21%; group II, 42%; and group III, 52%; p = 0.001). The plaque intrusion area (group I, 0.13 +/- 0.30 mm(2); group II, 0.25 +/- 0.42 mm(2); and group III, 0.31 +/- 0.40 mm(2); p = 0.018) and plaque intrusion volume (group I, 0.25 +/- 0.68 mm(3); group II, 0.40 +/- 0.68 mm(3); and group III, 0.75 +/- 1.34 mm(3); p = 0.007) were smallest in group I. The plaque intrusion area and plaque intrusion volume correlated with the ratio of the stent diameter to the average intravascular ultrasound reference lumen diameter (r = 0.278, p <0.001 and r = 0.283, p <0.001, respectively). The incidence of a creatine kinase-MB elevation >3 times normal was 6% in group I, 9% in group II, and 19% in group III (p = 0.025). No significant differences were found in the incidence of 1-year target lesion revascularization (group I, 13%; group II, 9%; and group III, 15%; p = 0.5) or target vessel revascularization (group I, 13%; group II, 13%; and group III, 15%; p = 0.9) among the 3 groups. In conclusion, the use of undersized drug-eluting stents to treat patients with saphenous vein graft lesions is associated with a reduction in the frequency of post-percutaneous coronary intervention creatine kinase-MB elevation without an increase in 1-year events.

Embolic protection: Limitations of current technology and novel concepts

Distal embolic event is one of the major limitations of coronary and non-coronary vascular interventions. Balloon and filter-based Embolic Protection Devices (EPDs) are a new class of interventional devices, used to prevent consequential morbidity and mortality of the distal embolic events. Data from first generation EPD supply proof of concept and show approximately 40% reduction in mortality and morbidity, when EPDs are used during saphenous vein grafts (SVGs) interventions. Current limitations of all first generation EPD technology taper their penetration. With breakthroughs in embolic protection technology, it is estimated that, in the near future, EPDs will be used with stenting in all high-risk lesions (SVGs, carotid arteries and acute coronary syndromes), become the standard of care and even be used in low risk cases.

Serial quantitative coronary analyses for the evaluation of one-year change in saphenous vein grafts

BACKGROUND

A paucity of data exists with respect to changes in whole saphenous vein grafts (SVGs) despite accelerated atherosclerosis within grafted saphenous vein conduits. In the present study, we evaluated the one-year change in SVGs by means of quantitative coronary analysis.

METHODS

This study enrolled consecutive 52 patients with 109 SVGs, who underwent coronary artery bypass graft surgery successfully. A follow-up study was performed in 33 patients with 65 SVGs after one year because 16 SVGs were obstructed (baseline, 8; follow-up period, 8), and 15 patients with 28 SVGs dropped out within one year.

RESULTS

Both minimal and mean lumen diameters decreased significantly (3.17 +/- 0.64 mm vs 2.41 +/- 0.57 mm, p < 0.001; 3.70 +/- 0.69 mm vs 2.92 +/- 0.70 mm, p < 0.001; respectively). Graft length also decreased significantly (107.1 +/- 25.8 vs 100.6 +/- 25.2 mm, p < 0.001). The graft shortening rate (graft shortening length/baseline graft length x 100) was greater than 5% in 33 vessels (51%) and greater than 10% in 23 vessels (35%). Coronary risk factors (smoking, diabetes mellitus, hypertension, dyslipidemia) did not reveal significant relationship with late loss of minimal and mean lumen diameters.

CONCLUSIONS

The present study showed a considerable and uniform lumen loss of SVGs after one year, irrespective of coronary risk factors. Graft length shortening was seen more than elongation.

Distal protection in cardiovascular medicine: current status

Iatrogenic and spontaneous downstream microembolization of atheromatous material is increasingly recognized as a source of cardiovascular morbidity and mortality. Devising ways of reducing this distal embolization using a variety of mechanical means--distal protection--is currently under intense and diverse investigation. This review therefore summarizes the present status of distal protection. It examines the problem of distal embolization, describes the available distal protection devices, reviews those areas of cardiovascular medicine where distal protection devices are being investigated, and discusses potential future developments.

Distal Protection Improved Reperfusion and Reduced Left Ventricular Dysfunction in Patients With Acute Myocardial Infarction Who Had Angioscopically Defined Ruptured Plaque

Background— Distal protection, in the Saphenous Vein Graft Angioplasty Free of Emboli (SAFER) trial, is demonstrated to prevent distal embolism in the percutaneous coronary intervention of saphenous vein graft. However, in the Enhanced Myocardial Efficacy and Recovery by Aspiration of Liberated Debris (EMERALD) trial, it was not effective in the percutaneous coronary intervention of native coronary arteries in patients with acute myocardial infarction (AMI). We hypothesized that its effectiveness would be determined by lesion characteristics. Therefore, we classified the type of culprit lesion by angioscopy and examined its influence on the effectiveness of distal protection, comparing patients with AMI treated with and without distal protection.

Methods and Results— Consecutive patients with AMI treated without distal protection (n=110) from July 2000 to July 2002 and those treated with distal protection (n=81) from July 2002 to July 2004 were included. Patients in each group were subdivided according to whether or not they had angioscopically defined ruptured plaque at culprit lesion. Among those groups, incidence of no-reflow phenomenon, ST-segment resolution, myocardial blush grade, and left ventricular ejection fraction at 6 months were compared. Aspirated samples by distal protection were semiquantitatively and histologically analyzed and compared between patients with and without ruptured plaque. No-reflow phenomenon was most frequently ( P <0.05) observed in patients with ruptured plaque treated without distal protection. ST-segment resolution (68±15% versus 40±21%, P <0.001), myocardial blush grade (2.6±0.5 versus 1.8±0.3, P <0.001), and left ventricular ejection fraction (47.2±6.7% versus 41.0±9.7%, P <0.01) were improved by distal protection among patients with ruptured plaque but not among patients without ruptured plaque. Aspirated samples >1 mm were detected more frequently (97.3% versus 78.5%, P <0.05) in patients with ruptured plaque than those without ruptured plaque. Histologically, aspirated samples contained plaque debris (95.3% versus 31.1%, P <0.05) more frequently in patients with ruptured plaque than in those without ruptured plaque.

Conclusions— Distal protection reduced microcirculation damage and left ventricular dysfunction in patients with AMI who had angioscopically defined ruptured plaque. Distal embolization of plaque debris was detected more frequently in patients with ruptured plaque. These results suggest that microcirculation damage and left ventricular dysfunction are increased mainly by distal embolization of plaque debris rather than of thrombus.

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.

Distal protection with a filter device during coronary stenting in patients with stable and unstable angina

BACKGROUND

Filter protection after percutaneous coronary intervention (PCI) is now available to prevent distal embolization. The aims of this study were (1) to evaluate the microembolization phenomenon during procedures of stent implantation in native coronary arteries of patients with stable and unstable angina, (2) to assess the amount and characteristics of the debris captured by the Angioguard, and (3) to investigate the relation between clinical and angiographic variables and pathological data.

METHODS AND RESULTS

Elective coronary stenting with the use of a protective filter was attempted in 39 consecutive coronary artery lesions with >60% stenosis (mean, 67.6+/-8.79%). Debris was present in 75.6% of the filters. Particle size ranged from 47.16 to 2503.48 microm (mean, 518.83+/-319.61 microm) in the major axis. Particles >300 microm were found in 24 of 28 filters with debris (85.7%), and particles >1000 microm were present in 10 of 28 filters (35.7%). Patients with unstable angina had greater particles (mean maximum longitudinal diameter, 1098.33+/-714.3 microm) than those with stable angina (412.91+/-453 microm; P<0.001). The presence of unstable angina (OR, 65; CI, 1.2 to 3420; P=0.03) and age >67 years (OR, 42; CI, 1 to 1698; P=0.04) were found to be the only independent predictors of embolic particle size.

CONCLUSIONS

By limiting embolization, protective devices may prevent a number of potentially unfavorable events, thereby improving outcome. Our data support the use of these devices, especially in lesions with higher embolic potential, such as those occurring in older patients and in those with unstable angina.

Stent deployment with distal vascular protection for the culprit vein graft stenosis in a patient with an acute infarct and cardiogenic shock

A case of emergency stent deployment to a critical vein graft lesion in a patient with an acute myocardial infarction and cardiogenic shock is described. An Angioguard vascular protection device was used, retrieving a large amount of atheromatous debris. Use of filter-type protection devices to prevent distal atheroembolism may be lifesaving in such patients.

Initial clinical experience with distal protection using the FilterWire in patients undergoing coronary artery and saphenous vein graft percutaneous intervention

Percutaneous coronary intervention (PCI) of saphenous vein grafts (SVG) and native coronary arteries may be associated with embolization of particulate debris into the distal microcirculation. The FilterWire uses a polyurethane filter bag contained on a radiopaque loop to trap embolic debris during native vessel and SVG intervention. The objectives of this study were to assess the feasibility and safety of the FilterWire during PCI and to examine the size and content of the particulate debris captured during SVG and native vessel intervention. Early angiographic, in-hospital, and 30-day clinical outcomes were reviewed in 35 patients with 36 lesions treated with the FilterWire during PCI. Lesions were located in 22 (61%) native coronary arteries and in 14 (39%) SVGs. Multivessel coronary artery disease was present in 75% of patients. Lesions were complex (ACC/AHA complexity B2 or C) in 81% of cases. The FilterWire was successfully delivered and deployed distal to the site of coronary intervention in 92% of lesions, including 95% of native vessels and 82% of SVG lesions. Embolic debris was entrapped in 82% of these cases. The average particulate debris had a mean major axis of 490 microm (range, 45-3,302 microm) and minor axis of 226 microm (range, 33-1,677 microm). Although reduced flow was common (36.1%) when the FilterWire was in place, there were no sustained episodes of abrupt closure and only one (2.8%) patient developed sustained no-reflow after FilterWire removal. Distal branch vessel embolization was found in four (11.1%) cases. Major adverse cardiac events occurred in 5 (14%) of 35 patients treated with the device, although 2 of these patients were evolving an acute myocardial infarction at the time of the procedure; in patients meeting the prospectively defined inclusion criteria, the major adverse cardiac event was 6%. These results suggest that the FilterWire is a feasible and safe method of collecting particulate debris released during SVG and native vessel coronary intervention. Its benefit over conventional therapy and other distal protection devices is currently under study.

Combined use of retrograde myocardial and distal coronary protection for last vessel intervention in an aortocoronary vein graft

Feasibility, safety, and clinical efficacy of the combined application of the PercuSurge system and the Myoprotect SSR device was demonstrated in a patient with high-risk anatomy undergoing saphenous vein graft intervention. This combined approach of coronary and myocardial protection may be considered in high-risk aortocoronary vein graft interventions.

Stent placement for non-STRESS/BENESTENT lesions: a critical review

Stenting lesions with favorable characteristics as required for inclusion in the STRESS/BENESTENT trials have yielded superior results to that of PTCA alone. Results for less favorable lesions such as in small vessels, diffuse disease, ostial disease, and saphenous vein grafts are less well established. This review seeks to analyze available data for stent placement in this subset of non-STRESS/BENESTENT lesions.

Retrieval and analysis of particulate debris after saphenous vein graft intervention

OBJECTIVES

This study was designed to evaluate the composition and quantity of particulate debris resulting from vein graft intervention.

BACKGROUND

Distal embolization and "no reflow" are frequent and important complications resulting from angioplasty of diseased saphenous vein grafts. Little is known about the composition and quantity of embolic particulate debris associated with vein graft intervention, and no intervention has been shown to protect against its clinical consequences.

METHODS

A catheter system, designed to contain, retrieve and protect against distal embolization of this material, was evaluated during 27 percutaneous interventional saphenous vein graft procedures. Clinical, angiographic and pathologic analyses were performed.

RESULTS

The duration of distal graft occlusion required to allow intervention and subsequent debris removal was 150 +/- 54 s, decreasing as experience was gained. Thrombolysis in Myocardial Infarction trial (TIMI) flow grade increased from 2.6 +/- 0.8 to 3.0 +/- 0.0. Creatine kinase (CK) rose above normal in three patients (11.1%) exceeding 3x normal in one (3.7%) resulting in the diagnosis of non-Q-myocardial infarction. Particulate material was identified following 21 of 23 procedures suitable for analysis. Particle size was 204 +/- 57 microm in the major axis and 83 +/- 22 microm in the minor axis. Particles consisted predominantly of soft acellular atheromatous material, such as that typically found under a fibrous cap. Semiquantitative analysis suggested that the quantity of particulate material was less following stenting than following balloon dilation.

CONCLUSIONS

Particulate matter is commonly present following routine angioplasty and stenting of saphenous vein grafts. Containment, retrieval and analysis of this particulate debris are all feasible. Comparison to prior clinical experience is limited by small sample size. However, to the extent that these particles may contribute to distal embolization, no-reflow and infarction, such a system may contribute to the reduction of complications following vein graft intervention.

Risk of distal embolization and infarction with transluminal extraction atherectomy in saphenous vein grafts and native coronary arteries. NACI Investigators. New Approaches to Coronary Interventions

Lower success rates have been reported when treating high-risk lesions in saphenous vein grafts (SVGs) and native coronary arteries with balloon angioplasty. The transluminal extraction atherectomy catheter (TEC) has been proposed to reduce the incidence of distal embolization (DE) in subsets of high-risk lesions. To define the utility of TEC in reducing the incidence of DE, all patients who were enrolled in the New Approaches to Coronary Interventions (NACI) Registry and had TEC planned as the sole treatment were studied (329 patients with 381 lesions). Of the lesions treated, 75.9% were in SVGs; 37.5% were thrombotic; and 15% were total occlusions. Adjunctive percutaneous transluminal coronary angioplasty (PTCA) was performed in 87.4% of lesions. Multivariate predictors of DE were: noncardiac disease, stand alone TEC, thrombus, and larger vessel size. DE was associated with an 18.5% in-hospital mortality vs. 3.0% without DE (P < 0.01) and a 25.9% MI rate vs. 5.0% without DE (P < 0.01). In conclusion, in this high-risk subset of patients, TEC is associated with an 8.3% incidence of DE with thrombotic and SVGs lesions. DE associated with TEC appears to carry high morbidity and mortality. Additional techniques to control DE are needed to reduce the frequency of complications in these patients.

An embolization containment device

A coaxial catheter system for containment of distal embolization is described. Utilizing a novel 0.014" hypotube with a distal elastomeric occlusion balloon, the PercuSurge GuardWire functions as a guidewire while trapping distal embolization resulting from more proximal intervention. The particulate debris is evacuated with a single operator exchange aspiration catheter (Export catheter) prior to deflation of the distal occlusion balloon. This animal study confirmed the feasibility of concept. The system was easily delivered through tortuous coronary anatomy. The GuardWire served as an adequate rail for delivery of dilatation balloons and a multitude of stents. There was no evidence of deep wall damage from low-pressure inflation and apposition of the distal occlusion balloon.

Interesting cases from the University of Texas Medical Branch

This article discusses the cases for four patients with unstable angina. The first case is an example of the "high-risk" patient with widespread ECG changes, heart failure, and enzymatic elevations during an episode of chest pain. The second patient illustrates an unusual cause of unstable angina in a young women. The third patient had a large thrombus visible on angiography and management strategies for dealing with intracoronary thrombus are discussed. The final patient had an extensive past cardiac history with two prior coronary artery bypass operations and we discuss the recent advances made in the treatment of degenerative vein graft disease.

Saphenous vein graft shrinkage as a mechanism of stenosis soon after bypass surgery

A 63-year-old man with left main coronary artery disease underwent aortocoronary bypass surgery using saphenous vein grafts. Less than 1 month later, severe narrowing occurred in the mid-portion of the vein graft to the left anterior descending coronary artery. Preintervention intravascular ultrasonography revealed prominent vein graft shrinkage. Percutaneous transluminal angioplasty failed because the stenotic lesion could not be dilated, even by high-pressure balloon inflation. Saphenous vein graft shrinkage appears to be one of the mechanisms of early saphenous vein graft stenosis, and balloon angioplasty to the vein graft stenosis with prominent shrinkage may be of only limited value.

Coronary artery and saphenous vein graft remodeling: a review of histologic findings after various interventional procedures--Part V

Catheter balloon angioplasty is a well accepted form of nonsurgical treatment of acutely and chronically obstructed coronary artery vessels. It is also the centerpiece for various new intervention techniques. Their morphologic effect on the site of obstruction has been termed "remodeling." Part V of this six-part series focuses on remodeling effects of balloon angioplasty on obstructed young (< or = 1 year) and old (> 1 year) saphenous vein bypass grafts.

Contemporary stent designs: technical considerations, complications, role of intravascular ultrasound, and anticoagulation therapy

A number of studies have shown the benefits of stent placement over balloon angioplasty for the treatment of focal, native coronary artery, and saphenous vein graft disease. Although the number of stent designs available for clinical use has increased dramatically, the late clinical benefit of stenting over balloon angioplasty has yet to be shown in diffuse disease, complex bifurcation stenoses, or smaller (2.5-mm) vessels, each of which may require unique stent designs and adjunct therapies not currently available or extensively studied. The purposes of this review are to discuss the various stent designs currently available for clinical use, outline the known complications associated with these stents, assess the contribution of intravascular ultrasound, and describe current antiplatelet and antithrombotic therapy used after stent use.

Clinical significance of distal embolization after transluminal extraction atherectomy in diffusely diseased saphenous vein grafts

Standard balloon angioplasty of degenerated saphenous vein graft lesions may be complicated by distal embolization, particularly in the presence of intragraft thrombus. Transluminal extraction atherectomy may be useful in this setting because of its ability to remove particulate debris. This study was designed to identify the incidence and prognostic significance of distal embolization after transluminal extraction atherectomy in high-risk saphenous vein graft lesions. To address these issues the clinical course of 65 consecutive patients (86 high-risk saphenous vein graft lesions) was reviewed after extraction atherectomy. Distal embolization occurred in 11 (12.8%) of 86 high-risk lesions. The majority (63.6%) of these episodes occurred after adjunct balloon dilatation following uncomplicated use of the extraction atherectomy catheter. Correlates of distal embolization included patient age and the presence of intragraft thrombus. Major in-hospital complications developed more often in patients with distal embolization (46% vs 2% in those without distal embolization, p < 0.001), resulting in a reduced procedural success rate in this group (55% vs 91%, p = 0.01). We conclude that the risk of distal embolization after saphenous vein graft angioplasty, although potentially reduced, is not eliminated with transluminal extraction atherectomy, particularly in lesions with superimposed thrombus.

Percutaneous angioscopy of saphenous vein coronary bypass grafts

OBJECTIVES

We compared the results of percutaneous angioscopy and angiography for detecting critical elements of surface lesion morphology in 21 patients undergoing balloon angioplasty of saphenous vein coronary bypass grafts.

BACKGROUND

Angiography remains the standard for diagnosing and treating intravascular pathology associated with atherosclerotic coronary artery disease. It has been demonstrated that coronary angioscopy is more sensitive for identifying more complex atherosclerotic plaques and intracoronary thrombi in native coronary arteries.

METHODS

Angioscopy and angiography were performed before and after angioplasty of "culprit lesions" in bypass grafts. All but one of the patients had unstable angina. The mean age of the saphenous vein coronary bypass grafts was 10.1 +/- 2.4 years (range 5 to 15).

RESULTS

Restenosis at a prior angioplasty site was present in seven patients. Intravascular thrombi were seen by angioscopy in 15 (71%) of 21 versus 4 (19%) of 21 grafts by angiography (p < 0.001). Dissection was identified by angioscopy in 14 (66%) of 21 versus 2 (9.5%) of 21 grafts by angiography (p < 0.01). The presence of friable plaque lining the lumen surface of the vein graft was detected by angioscopy in 11 (52%) of 21 versus 4 (19%) of 21 grafts by angiography (p < 0.05). There was no correlation between age of the bypass graft and the finding of friable plaque.

CONCLUSIONS

We conclude that angioscopy is superior to angiography for detecting complex lesion morphology in bypass grafts and that the presence of friable plaque does not preclude an uncomplicated angioplasty procedure.

Analysis of balloon dilatation of human vein graft stenoses

Controversy continues as to whether percutaneous transluminal angioplasty (PTA) or surgical revision is the ideal modality for the treatment of failing grafts. This prompted a histopathologic analysis of failing human vein graft segments subjected to ex vivo balloon dilatation to define variables responsible for the discrepant results. Fifteen vein graft lesions from 14 patients with failing infrainguinal bypasses were recovered after surgical excision. Each graft lesion was focal and uniform in length (2.1 +/- 0.3 cm). Rings sectioned from adjacent regions of each vein graft lesion before and after balloon inflation were processed for histologic study, photomicrography, and image analysis. Angioplasty balloon size was selected on the basis of preoperative arteriograms. Graft lesions were divided into three groups based on lesion thickness and the degree of fibrosis and cellularity seen on sections stained with Masson's trichrome. The luminal area before angioplasty was not significantly different for the three groups (p > 0.2). Vein grafts with thick intimas (group 1) had significantly less luminal dilatation after angioplasty as compared with less thick intimal lesions (groups 2 and 3; p < 0.001). Those lesions with varying degrees of cellularity (groups 2 and 3) showed no significant differences in luminal diameter after angioplasty. However, the cellular lesions in group 2 consistently formed multiple intimal flaps that could produce PTA failures even with good luminal restoration. The varying histology of vein graft lesions and associated differences in intimal thickness and cellularity may be responsible for the inconsistent results following PTA. Estimates of wall thickness before angioplasty, particularly in the intimal area, may be helpful in evaluating which lesions might benefit most from PTA.

Directional atherectomy for treatment of restenosis within coronary stents: Clinical, angiographic and histologic results

OBJECTIVES

The safety and long-term results of directional coronary atherectomy in stented coronary arteries were determined. In addition, tissue studies were performed to characterize the development of restenosis.

METHODS

Directional coronary atherectomy was performed in restenosed stents in nine patients (10 procedures) 82 to 1,179 days after stenting. The tissue was assessed for histologic features of restenosis, smooth muscle cell phenotype, markers of cell proliferation and cell density. A control (no stenting) group consisted of 13 patients treated with directional coronary atherectomy for restenosis 14 to 597 days after coronary angioplasty, directional coronary atherectomy or laser intervention.

RESULTS

Directional coronary atherectomy procedures within the stent were technically successful with results similar to those of the initial stenting procedure (2.31 +/- 0.38 vs. 2.44 +/- 0.35 mm). Of five patients with angiographic follow-up, three had restenosis requiring reintervention (surgery in two and repeat atherectomy followed by laser angioplasty in one). Intimal hyperplasia was identified in 80% of specimens after stenting and in 77% after coronary angioplasty or atherectomy. In three patients with stenting, 70% to 76% of the intimal cells showed morphologic features of a contractile phenotype by electron microscopy 47 to 185 days after coronary intervention. Evidence of ongoing proliferation (proliferating cell nuclear antigen antibody studies) was absent in all specimens studied. Although wide individual variability was present in the maximal cell density of the intimal hyperplasia, there was a trend toward a reduction in cell density over time.

CONCLUSIONS

Although atherectomy is feasible for the treatment of restenosis in stented coronary arteries and initial results are excellent, recurrence of restenosis is common. Intimal hyperplasia is a nonspecific response to injury regardless of the device used and accounts for about 80% of cases of restenosis. Smooth muscle cell proliferation and phenotypic modulation toward a contractile phenotype are early events and largely completed by the time of clinical presentation of restenosis. Restenotic lesions may be predominantly cellular, matrix or a combination at a particular time after a coronary procedure.

Palmaz-Schatz stent implantation in stenosed saphenous vein grafts: clinical and angiographic follow-up

Balloon-expandable stents may reduce the restenosis rate following coronary angioplasty. To evaluate this potential in saphenous vein grafts, 26 patients with 30 discrete stenoses underwent conventional balloon dilation and successful Palmaz-Schatz stent implantation as part of a multicenter trial. All patients had resolution of their angina following the procedure. In a mean 5-month follow-up period, 14 patients (54%, 16 lesions) had repeat arteriography; two patients (14%) developed recurrent ischemia ascribed to their venous grafts from in-stent restenosis (2 of 16 lesions, 13%). Two asymptomatic patients (8%) died: one from cardiac arrest (stent patent) and one from stroke (no autopsy). The clinical recurrence rate (cardiac death, myocardial infarction, bypass surgery, repeat angioplasty, or symptom recurrence) was 15%. These preliminary results show trends toward an improved primary success rate with combined vein graft angioplasty/stenting and a lower restenosis rate in stented saphenous vein grafts, but continuing follow-up will be needed to verify these observations.

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.

Stenting of coronary arteries: has a modern Pandora's box been opened?

Interventional cardiology has recently witnessed the growth of several alternatives to percutaneous transluminal angioplasty, including coronary stenting. Although stenting appears to be useful in treating abrupt closure after coronary angioplasty, its effectiveness in limiting the complex processes responsible for late restenosis is much less certain. Pathologic examination of stented human saphenous bypass grafts shows extensive deposits of platelets, fibrin and leukocytes along the stent wires within the 1st week and formation of a neointima of variable thickness after 3 months without evidence of foreign body reaction. The long-term effects of continuous barotrauma induced by the expanded stent remain unknown. It is difficult to assess the relative merits of the new devices, but stenting has several theoretic advantages. It seems less disruptive to the underlying architecture of the vessel wall and enjoys favorable theoretic and effective expansion ratios. Wide-spread clinical acceptance for stenting will depend on demonstrating that its safety, efficacy and cost efficiency are superior to those of balloon angioplasty.

The Dutch experience in percutaneous transluminal angioplasty of narrowed saphenous veins used for aortocoronary arterial bypass

Of 19,994 percutaneous transluminal coronary angioplasty procedures performed in The Netherlands between April 1980 and January 1989, the long-term follow-up of 454 patients who underwent angioplasty of greater than or equal to 1 saphenous vein bypass graft was reviewed. In 46% of patients single graft angioplasty was attempted, and in 54% of patients sequential graft angioplasty was attempted. The clinical primary success rate was 90%. In-hospital mortality was 0.7%, 2.8% of patients sustained a procedural myocardial infarction, and 1.3% of patients underwent emergency bypass surgery. After a follow-up period of 5 years, 74% of patients were alive, and 26% were alive and event-free (no myocardial infarction, no repeat bypass surgery or repeat angioplasty). In patients in whom the initial angioplasty attempt was unsuccessful, only 3% were event-free at 5 years, versus 27% of successfully dilated patients. The time interval between the angioplasty attempt and previous surgery was a significant predictor for 5-year event-free survival. The event-free survival rates for patients who had bypass surgery 1 year before, between 1 and 5 years, and 5 years before angioplasty, were 45, 25 and 19%, respectively. Less than one-third of patients with previous bypass surgery who had angioplasty of the graft remained event-free after 5 years. In patients needing angioplasty within 1 year after bypass surgery, better long-term results were achieved.

The effect of balloon angioplasty on vasa vasorum blood flow in canine coronary arteries

To assess the effects of balloon dilatation on vasa vasorum flow, we performed percutaneous transluminal coronary angioplasty on the circumflex arteries of 12 dogs. Left anterior descending and circumflex coronary vasa vasorum flows were measured with radioactive microspheres at baseline, during, and 10 minutes after a 3-minute, 8 atm balloon inflation. With inflation, vasa vasorum flow at the balloon dilatation site profoundly decreased (from 0.25 +/- 0.08 to 0.03 +/- 0.01 ml/min/gm). The flow returned to normal within 10 minutes after deflation. This effect was not mediated by hemodynamic deterioration during coronary occlusion and did not occur in the contralateral coronary artery. Endomyocardial flow in the distribution of the dilated artery decreased markedly during balloon inflation (from 1.14 +/- 1.9 to 0.08 +/- 0.04 ml/min/gm), which confirmed coronary occlusion. We conclude that a prolonged decrease in vasa vasorum flow is not produced by experimental balloon angioplasty, which makes it unlikely that a sustained vasa vasorum flow reduction plays a role in the maintenance of patency or the induction of restenosis.

Coronary angioplasty after coronary bypass surgery: initial results and late outcome in 422 patients

From 1978 to 1988, coronary angioplasty was performed in 422 patients with prior coronary artery bypass surgery (264 patients with native coronary artery angioplasty and 158 patients with graft angioplasty). Angioplasty was successful in 84%, unsuccessful but uncomplicated in 11% and complicated by one or more major cardiac events in 5% (myocardial infarction 5%, emergency bypass surgery 2% and death 0.2%). Follow-up data were obtained in 99% of 356 patients with successful angioplasty. At a mean of 33 +/- 26 months, 92% were alive, 73% had improvement in angina and 61% were free of angina. One or more of the following late events occurred in 67 patients (19%): myocardial infarction (6%), elective reoperation (13%) and cardiac death (6%). Repeat angioplasty was performed in 27%, with a success rate of 89% and no deaths. Initial success rates were equal in native vessel versus graft angioplasty, but late outcome was less favorable with the latter because of a higher rate of infarction (11% versus 4%, p less than 0.05) and need for reoperation (19% versus 10%, p less than 0.05). The initial success rate was higher in vein grafts less than 1 year old compared with grafts 1 to 4 years or greater than 4 years after operation (92% versus 85% versus 83%, respectively) and adverse late events were less frequent after angioplasty in recent vein grafts (less than 1 year 13%, 1 to 4 years 35%, greater than 4 years 29%; less than 1 versus greater than 1 year, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary angioplasty in patients with prior coronary artery bypass grafting

We studied the clinical and angiographic outcome of patients with prior coronary arterial bypass grafting who underwent percutaneous transluminal coronary angioplasty at the Royal Infirmary of Edinburgh. Over a 4 year period, 47 patients with prior bypass surgery underwent angioplasty of 23 stenotic graft sites and 37 stenotic sites of native vessels. The procedure was performed a mean of 31.3 months after surgery for recurrence of symptoms refractory to maximal medical treatment. Satisfactory angiographic results were achieved in 42 patients (58 stenotic grafts or native vessels). At a median follow up period of 18 months, 20 patients were symptomatically improved, but 22 patients experienced recurrence of symptoms a mean of 4.7 months after angioplasty, despite a good initial angiographic result. Overall, 4 patients had a repeat bypass grafting and 9 patients had a repeat angioplasty. Angioplasty can be used as an alternative to a repeat operation in patients with prior bypass grafting who experience recurrence of symptoms. Initial success rates are high and complication rates low. Restenosis or development of new lesions in the native circulation, and/or in the grafts, remain significant problems. Patients with a long asymptomatic interval (greater than 6 months) between the bypass operation and recurrence of symptoms are more likely to have better long-term results after successful angioplasty, perhaps because of slower progression of atherosclerotic heart disease.

Percutaneous transluminal angioplasty of saphenous vein graft stenosis: long-term follow-up

Percutaneous transluminal angioplasty was used to treat 101 patients with saphenous vein bypass graft stenosis at a mean of 50.1 months (range 2 to 196) after coronary artery bypass surgery. The patients presented between March 1981 and April 1987. A total of 107 saphenous vein grafts were dilated at 117 sites. The primary success rate was 91.8%. The incidence of cardiac complications was 7.1%. There were no cardiac complications in 53 patients with grafts implanted less than 36 months before angioplasty (Group 1). The 48 patients with grafts implanted for greater than 36 months (Group 2) had a 12.5% incidence rate of myocardial infarction, a 4% incidence rate of emergent bypass surgery and a 4% incidence rate of death for an overall cardiac complication rate of 14.9% (p less than 0.01). Follow-up was obtained at a mean of 16.8 +/- 13.9 months (range 1 to 54) in 87 patients (97% of successful cases). Repeat coronary angiography was performed in 49 patients and revealed restenosis in 30 patients (61.2%), with no difference in recurrence rates for proximal, mid or distal graft sites. Clinical recurrence (defined as recurrence of symptoms, myocardial infarction, repeat angioplasty, surgery or death) was 33.1% for Group 1 patients and 64.1% for Group 2 patients (p less than 0.01). The complication and recurrence rates of saphenous vein graft angiography are significantly higher when performed for late (greater than 36 months) vein graft failure. All therapeutic options should be carefully examined before proceeding with angioplasty for saphenous vein graft stenosis in this type of patient.

The clinical efficacy and scintigraphic evaluation of post-coronary bypass patients undergoing percutaneous transluminal coronary angioplasty for recurrent angina pectoris

The efficacy of percutaneous transluminal angioplasty in improving recurrent anginal symptoms and myocardial perfusion after coronary artery bypass graft surgery was assessed prospectively in 55 patients, of whom 50 had an initial angiographic and clinical success. Although 80% of those successfully dilated were initially free of angina at 23 +/- 11 months of follow-up, one half of these patients had recurrent angina. Although only 48% of the patient cohort had complete relief of angina, 94% had less angina than before dilatation and 86% were able to decrease antianginal medications. Fifteen patients with persistent or recurrent angina had from one to five repeat dilatations. After angioplasty, lung thallium uptake, the extent of abnormal scan segments, and the magnitude of redistribution in dilated lesions were significantly reduced (n = 24 patients). Redistribution defects were seen in 38% of patients on postangioplasty scans. All were associated with subsequent angina. Of various clinical, angiographic, exercise, and thallium-201 scan variables, only the presence of delayed redistribution was an independent predictor of recurrent angina. Restenosis was the most common underlying cause for this exercise-induced perfusion defect. Thus percutaneous coronary angioplasty performed as primary therapy for recurrent angina after bypass surgery is moderately successful in long-term follow-up for the amelioration of symptoms and enhancement of regional myocardial perfusion.

Balloon angioplasty of aortocoronary saphenous vein bypass grafts: a histopathologic study of six grafts from five patients, with emphasis on restenosis and embolic complications

Among 103 patients undergoing percutaneous transluminal balloon angioplasty of obstructed aortocoronary saphenous vein bypass grafts at the Mayo Clinic, six grafts from 5 patients were available for histopathologic examination. The interval from graft insertion to angioplasty ranged from 5 to 105 months and that from angioplasty to graft excision ranged from 6 h to 24 months. Angioplasty produced intimal fissures in three grafts initially obstructed by intimal fibromuscular proliferation. Healing and restenosis resulted from filling of lacerations with fibrocellular tissue and apparently also from restitution of muscular tone. In two of three grafts initially narrowed by atherosclerosis, balloon angioplasty cause extensive plaque rupture and restenosis resulted from extrusion of plaque debris and secondary luminal thrombosis. In the third graft, angioplasty produced no distinct lesions and late restenosis was due to progressive atherosclerosis of the vein graft. Atheroembolization was observed in both patients with plaque rupture and was associated with reoperation in one and death in the other. In conclusion, the results derived from six saphenous vein bypass grafts subjected to balloon angioplasty indicate that restenosis may result from intimal fibrocellular proliferation, thrombosis, restitution of muscular tone and progressive atherosclerosis. Symptomatic atheroembolization may occur in grafts greater than 1 year old.

Reduction in the rate of early restenosis after coronary angioplasty by a diet supplemented with n-3 fatty acids

To determine the safety and benefit of n-3 fatty acid therapy in the prevention of early restenosis after coronary angioplasty, we conducted a randomized, unblinded study comparing a conventional antiplatelet regimen (325 mg of aspirin and 225 mg of dipyridamole per day; control group) with a similar regimen supplemented with 3.2 g of eicosapentaenoic acid per day (treatment group). Treatment began seven days before angioplasty and continued for six months afterward. All angiographic analyses were blinded and performed by a method that was validated by comparison with quantitative coronary angiography. In 82 male patients, 103 coronary lesions were dilated. Both groups had similar base-line clinical and angiographic characteristics. The incidence of early vessel restenosis, as determined on a second angiogram three to four months after angioplasty, was 36 percent in the control group and 16 percent in the treatment group (P = 0.026). The incidence of restenosis per patient was also significantly lower in the treatment group (46 vs. 19 percent). Both multiple logistic regression and Mantel-Haenszel statistical analyses demonstrated a significant independent benefit of treatment with n-3 fatty acids. No important bleeding complications developed in the treated patients. These results, in a male population at relatively high risk for restenosis, suggest that a dietary supplement of n-3 fatty acids, administered for one week before and for six months after coronary angioplasty, is safe and reduces the occurrence of early restenosis after that procedure. Whether this beneficial effect also applies to other populations is unknown.

Percutaneous transluminal angioplasty in patients with prior myocardial revascularization surgery

Direct myocardial revascularization surgery using either the saphenous vein or internal mammary artery has become the definitive surgical treatment for coronary artery occlusive disease. Certain patients who have undergone these procedures, however, have recurrent myocardial ischemia due to progression of disease in unbypassed vessels, to obstruction in the arteries distal to the insertion of the bypass conduit, or to disease of the conduit itself. Balloon angioplasty may be used to relieve myocardial ischemia in these situations; however, initial studies suggested a low primary success rate coupled with excessive mortality and morbidity. Improvements in patient selection, equipment and technical expertise now allow angioplasty to be performed in this patient population with results comparable to that in the general coronary angioplasty population. Of the 3,016 angioplasty procedures performed between September 1980 and June 1987, 236 patients had previously undergone revascularization surgery. The primary success rate was 93% (390 of 419 stenoses successfully dilated). Overall, clinical restenosis was observed in 39%, including a 43% restenosis rate in patients undergoing only saphenous vein graft angioplasty. This did not differ appreciably from the restenosis rate in postbypass patients undergoing angioplasty of only native vessels (37%) or internal mammary arteries (42%). Emergency revascularization surgery was required in 7 of 236 patients (3%), each of whom had myocardial infarction. One of 236 patients (0.4%) died. Thus, angioplasty may be used to relieve recurrent myocardial ischemia in patients with prior direct myocardial revascularization procedures with a high initial success rate and acceptable risk. Early (less than 6 months) restenosis is not infrequent and remains the largest obstacle to a satisfactory clinical outcome.(ABSTRACT TRUNCATED AT 250 WORDS)

Saphenous vein graft rupture during percutaneous transluminal angioplasty

Three cases (one fatal) of a rare angioplasty complication, vein graft rupture, are presented with a review of the literature. Caution is suggested when oversizing balloons for vein graft dilatation.