Embolic Protection With Filtering or Occlusion Balloons During Saphenous Vein Graft Stenting Retrieves Identical Volumes and Sizes of Particulate Debris

A fresh look at coronary microembolization

Mechanical stress from haemodynamic perturbations or interventional manipulation of epicardial coronary atherosclerotic plaques with inflammatory destabilization can release particulate debris, thrombotic material and soluble substances into the coronary circulation. The physical material obstructs the coronary microcirculation, whereas the soluble substances induce endothelial dysfunction and facilitate vasoconstriction. Coronary microvascular obstruction and dysfunction result in patchy microinfarcts accompanied by an inflammatory reaction, both of which contribute to progressive myocardial contractile dysfunction. In clinical studies, the benefit of protection devices to retrieve atherothrombotic debris during percutaneous coronary interventions has been modest, and the treatment of microembolization has mostly relied on antiplatelet and vasodilator agents. The past 25 years have witnessed a relative proportional increase in non-ST-segment elevation myocardial infarction in the presentation of acute coronary syndromes. An associated increase in the incidence of plaque erosion rather than rupture has also been recognized as a key mechanism in the past decade. We propose that coronary microembolization is a decisive link between plaque erosion at the culprit lesion and the manifestation of non-ST-segment elevation myocardial infarction. In this Review, we characterize the features and mechanisms of coronary microembolization and discuss the clinical trials of drugs and devices for prevention and treatment.

Efficacy and safety of a magnesium stearate paclitaxel coated balloon catheter in the porcine coronary model

BACKGROUND

Local administration of growth-inhibiting substances such as paclitaxel or sirolimus could reduce the risk of restenosis. In the drug coated balloon (DCB) technology the coating and the applied dose seem to play a major role. The aim of the present preclinical studies was to investigate the efficacy and safety of a specific DCB with paclitaxel as active ingredient and magnesium stearate as excipient.

METHODS

Evaluation of the coating, drug release and transfer was done ex vivo and in vivo on peripheral arteries. A porcine coronary stent model was chosen to provoke intimal thickening. Conventional uncoated balloons were compared with paclitaxel urea and paclitaxel magnesium stearate coated balloons. QCA and histomorphometry was performed on treated vessels. Three areas of the heart were histologically examined for pathological changes.

RESULTS

QCA and histomorphometry revealed no differences in baseline data between treatment groups. All DCB groups showed a significant reduction of angiographic and histologic parameters describing neointimal formation 4 weeks after treatment (e.g. mean angiographic late lumen loss all coated 0.31 ± 0.18 mm versus 0.91 ± 0.37 mm in the uncoated balloon group). There were no device-related animal deaths or clinical abnormalities. In spite of very slight-to-slight microscopic findings limited to small arterial vessels in downstream tissue there was no change in left ventricular ejection fraction or angiographic presentation of small side branches of treated arteries.

CONCLUSION

Paclitaxel DCB using stearate as excipient show a high efficacy in reducing neointima formation after experimental coronary intervention. No evidence of myocardial damage resulting from distal embolization was found.

Novel Sirolimus–Coated Balloon Catheter

Background—

Limus-eluting stents are dominating coronary interventions, although paclitaxel is the only drug on balloon catheters with proven inhibition of restenosis. Neointimal inhibition by limus-coated balloons has been shown in few animal studies, but data from randomized clinical trials are not available. The aim of the present preclinical studies was to achieve high and persistent sirolimus levels in the vessel wall after administration by a coated balloon.

Methods and Results—

Different coating formulations and doses were studied in the porcine coronary model to investigate sirolimus tissue levels at different time points as well as efficacy at 1 month using quantitative coronary angiography and histomorphometry. Loss of the selected coating in the valve, guiding catheter, and blood was low (2±14% of dose). Acute drug transfer to the vessel wall was 14.4±4.6% with the crystalline coating, whereas the amorphous coatings were less effective in this respect. Persistence of sirolimus in the vessel wall until 1 month was 40% to 50% of the transferred drug. At 1-month follow-up, a modest but significant reduction of neointimal growth was demonstrated in a dose range from 4 μg/mm 2 to 2×7 μg/mm 2 , for example, maximum neointimal thickness of 0.38±0.13 versus 0.65±0.21 mm in the uncoated control group.

Conclusions—

Various sirolimus-coated balloons effectively reduce neointimal proliferation in the porcine coronary model but differ considerably in retention time in the vessel wall. It has to be determined if such a formulation with persistent high vessel concentration will result in a relevant clinical effect.

Embolization after percutaneous coronary intervention in acute coronary syndrome. Saphenous vein grafts versus native coronary arteries

AIMS

The aim of this study was to assess the occurrence of distal embolization and to quantify the amount of embolic material captured during stent implantation in native coronary arteries, as compared with saphenous vein grafts (SVG) in patients at different time periods after an acute coronary syndrome.

PATIENTS AND METHODS

In all, 104 patients presenting with unstable or stable angina underwent percutaneous coronary intervention (PCI) in 107 vessels and stent implantation in 112 lesions, 53 % of which were in SVG.

RESULTS

Device deployment and retrieval was successful in 111 lesions. Embolic material was detected in 74 % of the protection devices. Early PCI, during a 2-week period after the last ischemic episode, was associated with larger embolic load, especially in the right coronary artery. The length of the lesion was the only preprocedural independent variable that was found to be a significant predictor for the presence of emboli (p = 0.002). The stent diameter and the maximum dilatation pressure were the two procedural variables found to be significant predictors for the presence of emboli (p = 0.025 and p = 0.008, respectively). The irregularity of the lesion and the number of stents deployed were found to have a predictive correlation to the total area of the embolic particles (p = 0.04 and p = 0.005, respectively).

CONCLUSION

Distal embolization of atherosclerotic debris is a frequent phenomenon after PCI not only in SVG but also in native vessels. The amount of embolic material seems to be related to the atherosclerotic burden of the vessel and to the early timing of the procedure as related to acute coronary syndrome.

Propagation-based phase-contrast X-ray microtomography of a cerebral protection device retrieved after carotid artery stenting

Phase-contrast synchrotron X-ray microtomography (pcSyncX) based on the highly coherent X-ray beam has previously been used to visualize the microstructures of biologic specimens, but it has never been used to evaluate embolic debris adherent on a cerebral protection device (CPD). The purpose of this study was to demonstrate the feasibility of pcSyncX for evaluating embolic debris during carotid artery stenting (CAS). Five patients (four males, age range 67-77 years) with severe carotid artery stenosis underwent CAS. The retrieved CPD was exposed to synchrotron radiation and 1000 pcSyncX projection images were obtained by rotating the CPD through 180°. An X-ray shadow of a CPD was converted into a visual image by the scintillator. After microtomographic reconstruction, the three-dimensionally reconstructed images were further segmented into the embolic debris and CPD. The total volume of emboli was calculated by summing the volume at each scanning level. The number of membrane pores covered by emboli as seen from the outer surface was counted and the percentage of covered area was calculated. Embolic debris was clearly demonstrated not only on the inner surface and within pores but also on the outer surface of the CPD. The mean total volume of embolic debris was 0.538 × 10(-6) mm(3) (range 0.225-0.965 × 10(-6) mm(3)). Most (61.5%) of the debris was located at the apical one-third of the CPD and 20.8% of the pore area was covered by debris.

Embolic Protection Devices for Saphenous Vein Graft Percutaneous Coronary Interventions

Saphenous vein graft (SVG) percutaneous coronary interventions (PCIs) are associated with adverse clinical events caused by distal embolization in 10% to 20% of cases. Various embolic protection devices (EPDs) have been developed to lower the risk of distal embolization during SVG PCI: distal balloon occlusive devices, distal embolic filters, and proximal balloon occlusive devices. Despite evidence for improved outcomes and cost-effectiveness, rates of national EPD use remain low, the main cause of underutilization being operator preference. With increasing familiarity of operators with EPDs, their use should continue to increase in SVG PCI and lead to better outcomes.

[Filter content after carotid angioplasty and stenting: relation to ischemic lesions in diffusion-weighted imaging]

OBJECTIVES

To evaluate the relation between the material retrieved from distal filters after carotid angioplasty and stenting and the development of ischemic brain lesions in diffusion-weighted imaging (DWI). To determine the influence of demographic, clinical, and procedural variables in the pathogenesis of emboli and in ischemia after carotid angioplasty and stenting.

MATERIAL AND METHODS

We submitted the contents of the filters of 76 patients (60 men; mean age, 68.39 years; range, 46-82) who had undergone angioplasty and stenting for severe stenosis of the internal carotid artery for histologic analysis evaluating volume (< 1 λ = 0.001 ml = 1 μl; 1-10 λ; and > 10 λ) and the composition of the particles. All patients underwent DWI before and 24 hours after the procedure; we recorded whether lesions appeared and their number, size, and distribution. We correlated the findings with demographic, clinical, and procedural variables.

RESULTS

Symptoms were present before the procedure in 58 (76.3%) patients. Particles were present in 49 (64.5%) of the filters; most particles (77.5%) were 1 λ with a predominance of fibrin-platelet aggregates, cell remnants, and cholesterol crystals. DWI after the procedure detected lesions in 12 (15.8%) patients. We found no statistically significant correlation between filter contents and lesion detection after the procedure or between filter contents and other variables.

CONCLUSIONS

Ischemia after carotid angioplasty and stenting does not depend solely on the embolic load and its nature. We consider that the lower prevalence of postprocedural lesions in our series compared to others suggests that appropriate patient selection and experience minimize the negative influence of some variables like age in their development.

Initial clinical experience with distal embolic protection using "Filtrap", a novel filter device with a self-expandable spiral basket in patients undergoing percutaneous coronary intervention

We developed a new filter-type distal protection guide wire, Filtrap, that uses a polyurethane filter with 1834 100-μm micropores covering the distal half of a spindle-shaped spiral Ni-Ti basket. The basket is 5 mm in diameter, self-expandable, and is mounted at the distal end of the system. This study aimed to assess the usefulness and safety of Filtrap during percutaneous coronary intervention (PCI). Early angiographic and in-hospital outcomes were reviewed in 14 patients, including 9 acute coronary syndrome patients, treated with Filtrap during PCI. All lesions were located in native coronary arteries but one was located in a saphenous vein graft. The Filtrap was successfully delivered and deployed distal to the lesion in 13 of 14 patients (93%). All PCI procedures including stent implantation were successfully completed except for 2 AMI patients, who ended up with Thrombolysis in Myocardial Infarction (TIMI) 2 coronary flow. One of these 2 patients had a distal embolization which occurred after thrombectomy before Filtrap insertion. The mean time of device insertion was 9.4 ± 3.2 min. Five patients showed transient no-reflow that was completely restored immediately with removal of the device. Embolic debris was entrapped in 8 (62%) of these cases. All patients were free from in-hospital events except for one patient with a large anterior acute myocardial infarction who received an emergency surgery due to a free wall cardiac rupture. These results suggest that the Filtrap is a practical and safe device for embolic protection during PCI.

Proximal protection in recanalization of totally occluded saphenous vein grafts in acute coronary syndrome

Percutaneous treatment of old, degenerated saphenous vein grafts (SVG) is associated with a high likelihood of major adverse cardiac events. When an acute coronary syndrome (ACS) develops in a patient with old SVG, fresh thrombus may superimpose on an old, degenerative atheroma: a sudden increase in the athero-thrombotic burden ensues with consequent, frequent total occlusion of the lumen. In this scenario, transluminal recanalization of the graft is usually associated with the highest chance of distal embolization and no-reflow and positioning of an embolic protection device (EPD) is almost mandatory. However, distal EPD are difficult to place when the vessel is totally occluded and do not completely avoid distal embolization. We report two cases of totally occluded SVG in patients admitted for ACS that were recanalized with the aid of a proximal EPD system with angiographic and clinical success.

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.

Distal embolic protection during percutaneous coronary intervention in patients with acute coronary syndromes: The RUBY study

OBJECTIVE

To assess the safety and feasibility of the GuardWire system as an embolic protection device during percutaneous coronary intervention (PCI) in acute coronary syndromes (ACS).

BACKGROUND

Distal embolization occurs in approximately 15% of patients after primary angioplasty and is associated with reduced myocardial reperfusion, more extensive myocardial damage and a poor prognosis. Distal embolic protection could reduce the rate of embolic complications and improve outcome.

METHODS

329 patients (mean age 60+/-12 years) were included: 278 (84.5%) with ST-elevation myocardial infarction (STEMI), 50 (15.2%) with unstable angina/non-STEMI and 1 (0.3%) with post-infarction angina. Primary endpoint was the incidence of major adverse cardiac events (MACE) at 30 days. Secondary endpoints were the magnitude of ST-segment resolution at 90 and 180 min post-procedure, myocardial blush grade, and angiographically visible distal emboli.

RESULTS

The GuardWire system was successfully positioned in 99% of patients. Complete ST-elevation resolution (>70%) was observed in 28.5% immediately post-procedure, and in 35.4% and 41.6% at 90 and 180 min post-procedure. TIMI-3 flow grade was achieved by 89.8% of patients after intervention and mean corrected TIMI frame count was 20.2+/-13.2. Grade-3 myocardial blush was seen in 47.7% of patients and distal emboli were angiographically visible in 7.4%. Incidence of MACE at 30 days was 3.3% (death 1.2%; Q-wave MI 0.3%; non-Q-wave MI 0.3%; coronary artery bypass graft 0.6%; repeat PCI 0.9%).

CONCLUSION

The GuardWire system was successfully positioned in nearly all patients without complications. The use of this embolic protection device in ACS patients undergoing PCI was associated with low rates of distal embolization and 30-day MACE.

Observation of the embolus protection filter for Carotid Artery Stenting

BACKGROUND

Carotid artery stenting in patients with high surgical risk is considered as an effective alternative to carotid endarterectomy. Because the occurrence of distal embolization with CAS is still a major concern, an embolus protection device is usually used during the procedure. We developed a technique for observation of embolus protection filter and evaluated the debris or thrombus microscopically, and the pathologic findings were compared with preoperative imaging studies.

METHODS

After completing CAS, the filter membrane was stained with HE solution and removed from filter strut. Mounting onto a glass slide, the filter was evaluated under a microscope. Plaque debris and appearance of filter membrane were evaluated, and the covered area was measured. The pathologic findings were compared with preoperative imaging studies.

RESULTS

Microscopic observation of the slide revealed atheromatous debris as well as thrombotic material to the filter membrane. Hematoxylin-eosin stain facilitates the characterization of the debris composition, namely, thrombotic debris, calcified debris, organized debris, fibrous debris, and lipid-rich debris. The subtypes of debris were consistent with preoperative imaging studies. Thus, in cases of intraprocedural flow impairment, more than 50% of the filter area was covered with debris or thrombotic material.

CONCLUSION

Carotid plaque debris captured during carotid stenting with protection filter can be visualized with HE stain on the glass side. This simple method allows us to better understand the plaque debris and appearance of embolus protection filter.

In vitro analysis of downstream particulates with mechanical thrombectomy devices: comparison of 20-kHz sonothrombolytic and rotating dispersion wire systems

PURPOSE

To assess the potential of macroembolization, the authors compared the downstream particulate profile generated with use of two thrombectomy devices, a 20-kHz ultrasound-based sonothrombolytic (ST) device and a rotating dispersion wire (RDW).

MATERIALS AND METHODS

An arterial flow model was pressurized to 100 mm Hg and perfused with 1,000 mL/min normal saline. Tubing containing 7-mm x 30-cm bovine thrombus proximal to a 75% stenosis was inserted distal to a nonstenosed bypass. The effluent was passed successively through 1,000-, 500-, and 200-microm filters and a particle analyzer. The ST device and RDW were activated for 10 and 15 minutes, respectively, in randomized sequences of experimental sets with and without the use of 10-mg tissue-type plasminogen activator (tPA). Results are expressed as means and standard deviations of fraction of lysed clot in each category.

RESULTS

The ST device produced significantly fewer particulates larger than 1,000 microm (1.3% +/- 1.4) than did the RDW (16.8% +/- 8.4, P < .001) and significantly more particulates smaller than 10 microm (90.7% +/- 7.6) than did the RDW (73.9% +/- 9.5; P < .001) at comparable thrombolytic efficacy (P = .982) and without significant effect from tPA (P = .988). There were no significant differences between particles measuring 500-1,000 microm (ST device: 0.3% +/- 0.3, RDW: 0.4% +/- 0.3; P = .653) and those measuring 10-199 microm (ST device: 7.5% +/- 7.5, RDW: 8.6% +/- 3.8; P = .624). The amount of particles on the 200-microm filter after RDW activation (0.4% +/- 0.3) exceeded those trapped after use of the ST device (0.1% +/- 0.1, P = .007) but contributed relatively little overall.

CONCLUSIONS

In this in vitro model, the use of the ST device resulted in fewer large particulates than did the use of the RDW, with more clots being reduced to less than 10 microm.

Volume and composition of emboli in neuroprotected stenting of the carotid artery

BACKGROUND AND PURPOSE

Periprocedural microembolization is a major and permanent risk for patients treated by angioplasty and stent placement of high-grade carotid stenoses. Little is known however about the characteristics and significance of these embolized particles. Our aim was to assess the volume and composition of debris captured by filters during carotid angioplasty and stent placement (CAS) of severe internal carotid artery (ICA) stenoses.

MATERIALS AND METHODS

Institutional review board approval and informed consent from all subjects were obtained. Two hundred one patients (mean age, 66.2 years; range, 35-82 years) with > or = 70% stenosis of the ICA underwent filter-protected CAS. Ultrastructural and semiquantitative analysis of the volume of filters was obtained. Multifactorial statistical analysis was performed to determine factors related to debris volume and composition.

RESULTS

Transient ischemic attack occurred in 6 patients (3%), and a major stroke, in 1 (0.5%). Debris was found in 117 filters (58.2%), with volume <1 lambda (0.001 mL) in 71%. The number of balloon dilations, age older than 65 years, and calcified plaques in pre-CAS angiography were significantly associated with the presence of particulates inside the filters (P < .03, P < .004, and P < .05, respectively).

CONCLUSIONS

Vessel wall and atheromatous plaques are the main source of microemboli during CAS. Embolization is mainly related to the number of balloon dilations during CAS. Planning a proper and individualized strategy for the procedure in each patient is essential to minimize the potential effects of manipulation during CAS.

Microscopic and macroscopic evaluation of emboli captured during angioplasty and stent procedures in extracranial vertebral and internal carotid arteries

PURPOSE

To compare the quantities of emboli dislodged during percutaneous transluminal angioplasty/stenting in the vertebral artery (VA) with those released during stent placement in the internal carotid artery (ICA).

METHODS

Macroscopic images of distal protection devices (DPD) used during 30 stent procedures in 16 ICAs (11 men; mean age 64.6+/-10.6 years) and 14 VAs (9 men; mean age 67.1+/-9.8 years) were reviewed. The amount of captured embolic debris was calculated and expressed as a proportion to the size of the filter. Histological examinations were performed to characterize the material trapped in the filters.

RESULTS

Relative to the size of the filter, the proportion of captured debris ranged from 0.1% to approximately 22% in the ostial VA filters and from 0.1% to approximately 21% in the filters used in the ICA procedures (p = NS). Plaque fragments with or without thrombus were discovered in the histological examinations of captured material. There were no significant differences in the characteristics of the debris between the 2 vascular regions, nor did sex, race, or plaque morphology correlate significantly with the proportion of captured debris. However, the severity of stenosis was significantly (p<0.029) greater in the ICA (73%+/-0.11%) than the VA (63%+/-0.09%) territory.

CONCLUSION

The study suggests that the frequency and amount of captured emboli during stent procedures in ICA and ostial VAs are comparable. Therefore, the use of a DPD for stent placement in the vertebral artery may be advisable.

[Saphenous graft angioplasty]

In our daily practice the rate of saphenous graft angioplasty is less than 5%. This kind of angioplasty is more complex with a higher rate of complications in known fragile patients. Some technical trips and tricks are necessary to easily perform these angioplasties. Main difficulties are the extension of saphenous graft lesions, the risk of distal embolism, coronary slow or no flow and the high rate of restenosis. Pharmacological treatment is disappointing with no efficacy of the Gp IIb-IIa blockers. Otherwhise the use of protection devices is clearly effective and must be used when it is technically possible. With the use of bare metal stents in saphenous graft angioplasty the rate of restenosis is very high. There are some encouraging results with drug eluting stents. But we are still now not allowed to use them in this indication in our daily practice.

Particulate debris collected during carotid stenting: are we missing something?

Particulate and histopathologic examination of atherosclerotic material collected during carotid artery stenting is presented, illustrating the limitations of current knowledge regarding the use of distal protection devices (DPD) during this novel vascular intervention.

Embolic Protection Devices in Saphenous Vein Graft Interventions

Saphenous vein grafts (SVGs) are widely used as aortocoronary conduits during coronary artery bypass surgery and are critical in the high early success of coronary bypass revascularization. Saphenous vein grafts tend to be more prone than native coronary arteries to accelerated atherosclerosis and intimal fibrosis and thus frequently lead to recurrent symptoms and require further revascularization. Percutaneous coronary interventions (PCI) have become the prime means of SVG mechanical revascularization but are plagued by higher complication rates than PCI on native coronaries, largely due to embolic debris mobilized from around the target lesion in the SVG. Several mechanical devices and techniques have been developed to capture this friable material during the PCI before it can embolize; these devices have shown great promise in reducing the morbidity and mortality of these interventions and should be employed routinely.

Inflammatory and vasoactive factors in the aspirate from the culprit coronary artery of patients with acute myocardial infarction

BACKGROUND

Besides distal embolization of thrombus and plaque debris, locally increased inflammatory markers at the site of ruptured plaque in acute myocardial infarction (AMI) are thought to have an adverse impact on myocardial reperfusion during primary percutaneous coronary intervention (PCI). However, there is lack of data on such factors. Therefore, we investigated the presence of locally increased inflammatory and vasoactive factors in culprit coronary artery.

METHODS

We performed primary PCI with PercuSurge GuideWire system in 18 AMI patients. We collected blood samples from the femoral artery before PCI and from culprit coronary artery after first predilation while inflating the distal protection balloon and after completing PCI. We determined concentrations of C-reactive protein, soluble CD40 ligand, Interleukin (IL-6), serotonin, tissue factor, and factor VIIa.

RESULTS

While the concentrations of soluble CD40 ligand (2.84+/-3.74 vs 0.98+/-0.63 ng/mL, p=0.004), IL-6 (33.67+/-32.63 vs 17.08+/-21.41 pg/mL, p<0.001), serotonin (2.05+/-0.76 vs 0.92+/-0.60 ng/mL, p<0.001), tissue factor (257.17+/-84.34 vs 154.60+/-87.99 pg/mL, p<0.001) and factor VIIa (34.30+/-27.30 vs 24.19+/-28.00 ng/mL, p=0.016) were significantly higher in the culprit coronary artery than in the femoral artery, CRP levels did not differ. The locally elevated concentrations of various factors were successfully reduced after multiple aspirations of blood using the PercuSurge GuideWire system.

CONCLUSIONS

We found increased levels of soluble CD40 ligand, IL-6, serotonin, tissue factor and factor VII in the culprit coronary artery compared to those in peripheral blood. The clinical impact of such locally increased soluble factors in the culprit coronary artery needs to be investigated in further studies.

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.

Intense Vasoconstriction in Response to Aspirate From Stented Saphenous Vein Aortocoronary Bypass Grafts

OBJECTIVES

We sought to identify soluble vasoconstrictor substances that are released during stent implantation into saphenous vein aortocoronary bypass grafts.

BACKGROUND

Atherosclerotic saphenous vein aortocoronary bypass grafts are particularly vulnerable to plaque rupture. Protection devices prevent particulate debris from being embolized. Additional soluble vasoconstrictor substances possibly also contribute to impaired microvascular perfusion.

METHODS

Peripheral venous blood (VB) and aspirate (AS) were obtained from 14 patients with a significant stenosis in a saphenous vein graft during stent implantation under protection with a distal balloon occlusion device. In five additional patients, arterial blood (AB) was also taken distal to the stented lesion before intervention. Vasomotor substances in VB, AB, and AS plasma were identified in a bioassay of rat mesenteric arteries with intact (+E) and denuded endothelium (-E). Vasoconstriction was normalized to that induced by potassium chloride depolarization (100%).

RESULTS

Venous blood, AB, and AS plasma induced maximum vasoconstriction within six minutes. The AS plasma induced a vasoconstriction of 138 +/- 13% (-E) and 87 +/- 14% (+E); VB, of 70 +/- 14% (-E) and 23 +/- 4% (+E); and AB plasma obtained before intervention, of 49 +/- 9% (-E) and 36 +/- 8% (+E). The vasoconstrictor potency of AS plasma in endothelium-denuded vessels was related to the severity of anginal symptoms, angiographic stenosis severity, plaque volume, and plaque burden as determined by intravascular ultrasound. The AS plasma-induced vasoconstriction was largely attenuated by combined serotonin/5-hydroxytryptamine (5-HT)(2A/2C)- and 5-HT(1A/1B)-receptor blockade and eliminated by additional thromboxane A2 thromboxane-prostanoid (TP)-receptor blockade.

CONCLUSIONS

Stent implantation releases, apart from and in addition to particulate debris, soluble vasoconstrictor substances that possibly contribute to impaired microvascular perfusion.

EMERALD, AIMI, and PROMISE: is there still a potential for embolic protection in primary PCI?

The recent trials of routine use of embolic protection devices for primary percutaneous coronary interventions (PCI) (the EMERALD, PROMISE, and AIMI trials) have demonstrated neutral or even negative effects of these devices on myocardial reperfusion and final infarct size. Despite these results, there is still ground to believe that PCI-induced embolization may be clinically relevant in specific subsets of patients with acute myocardial infarction (AMI). Significant clinical consequences may be expected when embolization is quantitatively relevant and/or is qualitatively characterized by lipid-rich athero-embolism (as is the case of lipid core embolization through the ruptured cap of a fibro-atheroma). Future trials on embolic protection devices in primary PCI should adopt a selective, rather than a routine strategy, through the identification, by angiographic or intravascular imaging parameters, of patients at highest risk of clinically relevant embolization. Such trials should also adopt specific endpoints able to evaluate the effect of micro-embolization, which is currently far from optimally assessed by the standard markers of myocardial reperfusion.

Effects of thrombus suction therapy on myocardial blood flow disorders in males with acute inferior myocardial infarction

Several studies have reported that the use of a distal protection device decreases the incidence of slow-flow and/or no-reflow in patients with myocardial infarctions. In the present study, we investigated the influence of a RESCUE/Thrombuster system and a PercuSurge GuardWire catheter on coronary microcirculation disorders in patients with acute myocardial infarction using the natriuretic polypeptide (ANP), the brain natriuretic peptide (BNP), and (99m)Tc-tetrofosmin myocardial scintigraphy (TF). The group consisted of a 77 patients with initial inferior myocardial infarction who had undergone emergency coronary angioplasty. The patients were randomly divided into: Group D (n=28), in which a direct stent alone was inserted, Group R/T (n=25), in which a stent was inserted after RESCUE system or a Thrombuster system was performed, and Group P (n=24), in which a stent was inserted after thrombus suction using a PercuSurge GuardWire catheter. Patients with coronary slow-flow/no-reflow were 3, 2 and 0 cases in Group D, Group R / T and Group P, respectively. In the present study, patients with good-reflow were enrolled in order to investigate the coronary microcirculation disorder in patients with visually similar coronary blood flow obtained in coronary angiography after percutaneous coronary reperfusion therapy. TF myocardial scintigraphy was performed 10+/-3 days after admission. Bull's eye images were divided into 8 sections, and each section was evaluated in 4 grades. The grade of each segment was regarded as the defect score. The results were compared with the database prepared based on bull's eye maps from 50 healthy adults in our hospital, and count areas of -2 x SD (standard deviation) or less were calculated as the extent score (%), reflecting the area in which myocardial blood flow was decreased. The extent and severity scores in Groups P and R/T were significantly lower than those in Group D. Coronary angiography at the chronic stage (6 months after surgery) showed the patency of the responsible vascular lesion in all patients. However, the ANP, BNP, cardiac index, and pulmonary capillary wedge pressure (PCWP) were significantly improved in Groups R/T and P, compared to Group D (p<0.01). These results suggest that the use of a RESCUE/Thrombuster system and a PercuSurge GuardWire catheter system in patients with acute inferior wall infarction improves coronary microcirculation disorders and acute- to chronic-phase cardiac function.

Distal Embolic Protection for SVG Interventions: Can We Afford Not to Use It?

The development of atherosclerosis in saphenous vein grafts (SVGs) is one of the limiting factors in coronary artery bypass surgery. Approximately one half of vein conduits are significantly diseased or occluded at 10 years. A surgical revascularization strategy is often not pursued secondary to the incremental risks associated with a repeat bypass procedure. For this reason, percutaneous treatment of SVG disease is often the first option for a majority of patients. However, catheter-based treatment of SVG disease is associated with increased morbidity and mortality compared with native coronary arterial percutaneous intervention. This is often the result of distal embolization of atherothrombotic disease, leading to the phenomenon of "no-reflow." Intraprocedural pharmacological therapy has historically been the mainstay of treatment for these patients. However, more recently, the development of a mechanical embolic protection device has shown to be beneficial for the prevention of these complications. This article will review the types of embolic protection devices and the clinical studies that have proven their necessity in percutaneous SVG intervention.

A randomized, controlled trial of saphenous vein graft intervention with a filter-based distal embolic protection device: TRAP trial

The purpose of this prospective, multicenter trial was to evaluate the safety and effectiveness of the TRAP Vascular Filtration System (VFS) to reduce embolic complications during stenting of diseased saphenous vein grafts (SVGs). Patients with SVG lesions were randomly assigned to undergo stenting with or without the TRAP device. The trial was designed to enroll 752 randomized patients. However, the sponsor terminated the study after a total of 467 patients (358 randomized) were enrolled because of poor recruitment once another distal protection device was approved for clinical use. The primary study endpoint, major adverse cardiac events at 30 days, occurred in 17.3% of control patients and 12.7% of patients treated with the TRAP device (P = 0.24). There was a trend toward a lower incidence of myocardial infarction in the TRAP group compared with the control group (16.2% vs 10.5%, P = 0.12). This difference was predominantly due to a lower incidence of moderate-large infarction (CKMB >5x) in the TRAP group. Use of the TRAP VFS during SVG intervention was safe and was associated with a trend toward a lower incidence of adverse events, however, due to low enrollment the study lacked sufficient power to detect a significant benefit with the device.

Peri-procedural myocardial injury: 2005 update

During the past three decades, percutaneous coronary intervention has become one of the cardinal treatment strategies for stenotic coronary artery disease. Technical advances, including the introduction of new devices such as stents, have expanded the interventional capabilities of balloon angioplasty. At the same time, there has been a decline in the rate of major adverse cardiac events, including Q-wave acute myocardial infarction, emergency coronary artery bypass grafting, and cardiac death. Despite these advances, the incidence of post-procedural cardiac marker elevation has not substantially decreased since the first serial assessment 20 years ago. As of now, these post-procedural cardiac marker elevations are considered to represent peri-procedural myocardial injury (PMI) with worse long-term outcome potential. Recent progress has been made for the identification of two main PMI patterns, one near the intervention site (proximal type, PMI type I) and one in the distal perfusion territory of the treated coronary artery (distal type, PMI type II) as well as for preventive strategies. Integrating these new developments into the wealth of clinical information on this topic, this review aims at giving a current perspective on the entity of PMI.

[Acute coronary syndrome: unstable angina and myocardial infarction]

The acute coronary syndrome comprises unstable angina, non-ST-segment elevation myocardial infarction, and ST-segment elevation myocardial infarction. A successful and stable revascularisation of the infarct related vessel, and the prevention of the loss of myocardium are the main therapeutic targets, as cardiovascular mortality and long term quality of life are essentially determined by left ventricular function. The clinical diagnosis comprises clinical symptoms, ECG-changes, and cardiac troponins. Early percutaneous coronary intervention (PCI) has become the most common method of coronary revascularisation. If PCI is not available, systemic thrombolysis is an alternative after exclusion of contraindications. Parenteral anticoagulation with intravenous or subcutaneous heparines, antithrombotic therapy and HMG-CoA reductase inhibitors are the common secondary drug therapy. Moreover, to prevent left ventricular remodelling ACE-inhibitors, angiotension 2-receptor antagonists, and beta-blocker are indicated.

Distal embolization during primary angioplasty: histopathologic features and predictability

BACKGROUND

Distal embolization during primary percutaneous coronary interventions (PCIs) may affect myocardial reperfusion. We evaluated the prevalence and features of embolization during primary PCI and its relationship with clinical and angiographic variables.

METHODS

Forty-six consecutive patients with acute myocardial infarction underwent primary PCI with a filter-based distal protection device. Histopathologic analysis was performed on retrieved embolic fragments, assessing the presence and relative amount of fibrin, necrosis, lipid droplets, collagen, mucopolysaccharides, and leukocytes, as well as the total debris volume. Such variables were related to baseline clinical and angiographic variables.

RESULTS

Embolic material was recovered in 41 (89%) of 46 cases, with a mean total debris volume of 1.2 +/- 2.2 mm3. Prevalent histopathologic patterns were organized thrombus (47%), fresh thrombus (29%), and plaque fragments (24%). At multivariate analysis, none of the baseline clinical variables considered significantly predicted the total debris volume. Among angiographic variables, angiographic signs of high thrombus burden (cut-off coronary occlusion pattern or large intracoronary minus image) independently predicted the total debris volume at multivariate analysis (odds ratio 15.8, P < .005). Compared with its nonuse, abciximab did not affect the total number and the mean total volume of embolized material (15 +/- 16 vs 10 +/- 8 fragments, 1.5 +/- 2.5 vs 1.0 +/- 1.9 mm3, respectively, for both P > .20), or its qualitative composition.

CONCLUSIONS

Distal embolization occurs in most patients during primary PCI and mainly consists of plaque fragments and partially organized thrombi, which are likely to be scarcely responsive to antiplatelet drugs. Baseline angiographic signs of a high thrombus burden are the only significant predictors of the extent of distal embolization.

Embolic protection devices for carotid artery stenting: is there a difference between filter and distal occlusive devices?

OBJECTIVES

We sought to compare the efficacy of a filter embolic protection device (F-EPD) and a distal occlusive embolic protection device (DO-EPD) in patients undergoing carotid artery stenting (CAS).

BACKGROUND

The embolic protection device (EPD) may lower the periprocedural rate of cerebral ischemic events during CAS. However, it is unclear whether there is a difference in effectiveness between the different types of EPD.

METHODS

We analyzed data from the Carotid Artery Stent (CAS) Registry.

RESULTS

From July 1996 to July 2003, 1,734 patients were included in the prospective CAS Registry. Of these patients, 729 patients were treated with an EPD, 553 (75.9%) with F-EPD, and 176 (24.1%) with DO-EPD. Patients treated with DO-EPD were more likely to be treated for symptomatic stenosis (64.5% vs. 53.4%, p = 0.011). The carotid lesions in patients treated under DO-EPD seemed to be more complicated, as expressed by a higher proportion of ulcers (p = 0.035), severe calcification (p = 0.039), a longer lesion length (p = 0.025), and a higher pre-interventional grade of stenosis (p < 0.001). The median duration of the CAS intervention was 30 min in the DO-EPD group, compared with 48 min in the filter group (p < 0.001). No differences in clinical events rate between the two groups of protection devices were observed. Multivariate analysis on the occurrence of the combined end point of in-hospital death or stroke found no difference between filter- and DO-EPD (4 of 176 [2.3%] for DO-EPD vs. 10 of 551 [1.8%] for F-EPD; adjusted odds ratio = 1.04, 95% confidence interval 0.24 to 4.44; p = 0.958).

CONCLUSIONS

Filter EPD is the currently preferred method of EPD in clinical practice. Both F-EPD and DO-EPD seem to be equally effective during CAS.

Morphometric analysis of particulate debris extracted by four different embolic protection devices from coronary arteries, aortocoronary saphenous vein conduits, and carotid arteries

Different embolic protection devices have been introduced for endovascular interventions: filters or balloon occlusion and aspiration systems. Despite widening use in a variety of vascular beds and clinical syndromes, little is known about the particulate burden liberated from different vascular beds and caught by different protection devices. We performed histologic and morphometric analyses of particulate debris captured during stenting of degenerated saphenous vein bypass grafts and native coronary arteries during acute myocardial infarction or during elective intervention and carotid arteries to assess the relative performance of different protection devices. We analyzed 232 interventions (90 saphenous vein bypass grafts, 77 native coronary arteries, and 65 carotid arteries) with 4 different devices (65 FilterWires, 99 Interceptors, 41 GuardWires, and 27 Proxis catheters) using the RapidVue particle analyzer. No difference in embolic volume retrieved was demonstrated between devices in saphenous vein bypass grafts and carotid interventions. A smaller volume of particulate debris was retrieved by the GuardWire compared with the FilterWire and the Proxis catheter in native coronary artery interventions. The Interceptor and the GuardWire captured more smaller particles than did the FilterWire or Proxis catheter. During saphenous vein bypass graft or carotid intervention, different embolic protection strategies were performed similarly. In native coronary artery stenting, however, proximal embolic protection retrieved larger amounts of debris than did distal filters or occlusion devices. These data may allow greater tailoring of embolic protection device development and application in specific anatomic locales.

A novel, low-profile filter-wire (Interceptor) embolic protection device during saphenous vein graft stenting

A novel, low-profile filter embolic protection device was deployed in 26 patients who underwent stent deployment for saphenous vein graft stenoses in a multicenter trial. Major adverse cardiovascular events were observed in only 2 patients (7.7%) and angiographic flow grades were improved.