Embolic protection devices

Comparison of transseptal puncture using a dedicated RF wire versus a mechanical needle with and without electrification in an animal model

INTRODUCTION

Mechanical force to achieve transseptal puncture (TSP) using a standard needle may lead to overshooting and injury, and can potentially be avoided using a radiofrequency (RF)-powered needle or wire. Applying electrocautery to needles and guidewires as an alternative to purpose-built RF systems has been associated with safety risks, such as tissue coring and thermal damage. The commercially available AcQCross needle-dilator system (Medtronic) features a sharp open-ended needle for mechanical puncture, as well as a built-in connector to enable energy delivery for RF puncture. This investigation compares the safety and efficacy of the AcQCross needle to the dedicated VersaCross RF wire system and generator (Baylis Medical/Boston Scientific).

METHODS

In an ex vivo porcine model, VersaCross wire punctures were performed using 1 s, constant mode (approx. 10 W) with maximum two attempts. AcQCross punctures were performed by applying energy for 2 s using a standard electrosurgical generator at 10 W (max. five attempts), 20 W (max. two attempts), and 30 W (max. two attempts). Efficacy was assessed in terms of puncture success and a number of energy applications required for TSP. Safety was assessed quantitatively as force required for TSP, energy required to puncture, and incidence of tissue coring, as well as by qualitative assessment of puncture sites. Additional qualitative observation of tissue cores and debris were obtained from TSP performed in live swine.

RESULTS

RF TSP was 100% successful using the VersaCross wire with 1.0 ± 0.0 attempts. When power was used with the AcQCross needle, it failed to puncture at low (10 and 20 W) power settings; TSP was achieved with 30 W of energy with 91% success using 1.53 ± 0.51 attempts (p < .05 vs. VC) with greater variability (F1,33  = 9223.5, p < .0001). Compared to RF puncture using the VersaCross system, mechanical puncture, alone, using the AcQcross needle required six times more force (8 mm additional forward device displacement) to perforate the septum. Qualitative assessment of puncture sites revealed larger defects and more tissue charring with the AcQCross needle at 30 W compared to punctures with VersaCross wire. Tissue coring with the open-ended AcQCross needle was observed in vivo and measured to occur in 57% of punctures using the ex vivo model; no coring was observed with the closed-tip VersaCross wire.

CONCLUSIONS

The AcQCross needle frequently required higher energy of 30 W to achieve RF TSP and was associated with tissue coring and charring, which have been, previously, reported when electrifying a standard open-ended mechanical needle or guidewire. These findings may limit safety and effectiveness compared to the VersaCross system.

Extended Use of Distal Embolic Protection Devices in Treatment of Distal Embolism During Lower Extremity Arterial Endovascular Interventions

There is no consensus on the best treatment modality for acute distal embolization complications during endovascular interventions for peripheral arterial diseases. We report on 3 patients who underwent mechanical embolectomy using a distal embolic protection device (EPD). All patients showed angiographic evidence of distal embolism, which occurred during lower extremity limb salvage endovascular procedures. After embolectomy, all had complete recanalization of the involved vessel on completion angiogram, and none had any device-related complications or adverse outcomes from the embolization. This initial experience suggests that EPD can be used for both the prevention and treatment of intraoperative distal embolization during endovascular intervention of lower extremity arterial disease.

Carotid artery stenting in patients with chronic internal carotid artery occlusion

BACKGROUND

The risk of ischemic stroke in patients with chronic total occlusion (CTO) of the internal carotid artery (ICA) on best medical treatment has been estimated to be 5.5% per year. The purpose of this study was to assess early and mid-term outcome of patients who underwent an attempt at transfemoral carotid artery stenting (CAS) for CTO of the ICA.

METHODS

Clinical data of symptomatic patients who underwent attempt at CAS for CTO of the ICA between January 1, 2010 and July 1, 2020 were retrospectively reviewed. Clinical success, perioperative and mid-term stroke and death rates were recorded. Descriptive statistics were used.

RESULTS

There were 27 patients, 14 females, 13 males, with a mean age of 66.8 years, range: 57 to 79. All patients had symptoms within 6 months prior to the procedure. 16 had ipsilateral stroke at a mean of 2.8 months, ranges: 1.5-4 months, two had transient ischemic attack (TIA), at 1 week and at 6 months, one had amaurosis fugax at one week, two had chronic ocular ischemia and six had chronic cerebral hypoperfusion. Technical success was 52% (14/27). One patient developed a minor reversible stroke (1/27, 3.7%) there was no early death, for an overall 30-day stroke and death rate of 3.7% (1/27). Two patients had perioperative TIAs. Among 14 patients with successful CAS (group A) one had minor, reversible ipsilateral stroke during a follow-up of 29 months (range: 4-112), two had contralateral stroke. There was no death. One patient developed asymptomatic stent occlusion, three had asymptomatic in-stent restenosis >50%, two had reinterventions. Among patients with unsuccessful attempt at CAS (group B), 31% (4/13) had stroke at 4, 10, 14 and 22 months, respectively. One stroke patient died at 10 months.

CONCLUSIONS

Transfemoral CAS of symptomatic patients with CTO of the ICA was feasible in half of the patients, with no mortality or major stroke, for an overall early stroke/death rate of 3.7%. Since one third of the patients with unsuccessful stenting developed stroke during follow-up, further studies to investigate the safety, efficacy and durability of CAS for CTO of the ICA are needed.

A systematic review of endovascular treatment for chronic total occlusion of the internal carotid artery

The management of patients with symptomatic chronic total occlusion (CTO) of the internal carotid artery (ICA) is controversial. The aim of this systematic review was to investigate patient selection, technical success, early and late outcome of endovascular treatment for CTO of the ICA. PubMed/Medline and EMBASE databases were searched until January 2, 2020 for studies on endovascular treatment for CTO of the ICA. A descriptive analysis of demographic, clinical and anatomic data, endovascular technique, perioperative and late outcomes was performed. A total of 1,222 articles were screened, 8 retrospective or prospective cohort studies were reviewed; 276 patients, 18.9% females, mean age: 64.3 years, underwent attempt at endovascular treatment of 278 lesions. Two hundred and thirteen patients (77.2%) had neurological symptoms; the others had evidence of ipsilateral cerebral hypoperfusion. Two hundred and thirty-eight lesions (91.2%) were treated >30 days after diagnosis of occlusion. Technical success was 66.9%. Perioperative mortality was 1.64% (4/243), early stroke rate was 3.3%. Follow-up averaged 23.4 months (range, 0.25–84 months), late mortality was 1.89% (5/265), stroke rate was 3.4% (9/265). Stroke rate was similar after successful stenting (3.57%, 4/112) vs. failed stenting (3.61%, 2/61; P=1.00), stroke/death rates were also similar after successful stenting (5.36%, 6/112) than after failed stenting (3.28%, 2/61; P=0.71). Endovascular treatment of CTO of the ICA in eight cohort studies was safe and feasible with a technical success of 67% and a low rate of early and late neurological complications. Pooled data in this review failed to confirm the benefit of successful stenting on stroke and mortality, but some of the included studies suggest benefit and some also supported improvement in neurocognitive function after successful stenting. Prospective randomized trials to investigate the benefit of endovascular treatment in addition to best medical therapy for symptomatic CTO of the ICA are urgently needed.

Use of Embolic Protection Devices in Peripheral Interventions

The use of embolic protection devices (EPDs) when treating coronary saphenous vein bypass grafts, performing carotid arterial stenting and treating acute coronary syndromes is well accepted. We will review currently available devices and approaches to reduce distal embolisation, first discussing their uses in carotid interventions and then in vertebral and peripheral vascular interventions.

Intraprocedural Distal Embolization After Femoropopliteal Angioplasty: Is There a Role for Below-the-Knee Stents?

PURPOSE

Intraprocedural distal embolization is an accepted complication of femoropopliteal angioplasty. The purpose of this study is to assess the use of below-the-knee stents in the "bail-out" of conventional methods.

MATERIALS AND METHODS

We retrospectively reviewed 1485 of femoropopliteal angioplasties that were performed in our centre in a 4-year period and analysed 12 cases (<1%) where distal embolization that required further intervention occurred. In all cases lesions were chronic and 75% suffered from critical limb ischaemia. The target vessel was the SFA in all of the cases with a long (>10 cm) occlusion in 50%. A three-vessel run-off was present in only 25%. Patients that received a stent as a limb salvage attempt were analysed. Outcome measures were technical success, clinical success and procedure-related complications. Multivariate regression analysis of the factors related to stenting was also performed.

RESULTS

In 41% of the cases with distal embolization, recanalization with aspiration, thrombolysis or angioplasty offered a satisfactory result. In 59%, conventional methods were ineffective; a stent was deployed in 85%, whereas in 15% surgical embolectomy was required. Technical and clinical success of the stent cases was 100% without any procedure-related complications. There was significance (p < 0.05) between critical limb ischaemia and stenting; single-vessel run-off has also shown a positive trend (p = 0.88).

CONCLUSION

Stents appear as a valid salvage option for infragenicular distal embolization when conventional methods fail; the likelihood of having to use a stent is higher for patients with critical limb ischaemia and a single-vessel run-off.

Immunohistochemical Analysis of Debris Captured by Filter-Type Distal Embolic Protection Devices for Carotid Artery Stenting

BACKGROUND

Little is known about the micro-debris captured in filter-type distal embolic protection devices (EPD) used for carotid stenting (CAS). This study aimed to determine the histological and immunohistochemical characteristics of such debris by using a new liquid-based cytology (LBC) technique.

METHODS

Fifteen patients who underwent CAS using a filter-type distal EPD (FilterWire EZ; Boston Scientific, Marlborough, MA, USA) were included in the study. After gross inspection of each recovered filter device, micro-debris were collected using a new LBC technique (SurePath; TriPath Imaging, Inc., Burlington, NC). Histological and immunohistochemical analysis of the recovered debris was performed. The pre- and postoperative brain magnetic resonance imaging and neurological status of each patient were also reviewed.

RESULTS

No patient developed ipsilateral symptomatic stroke due to a thromboembolic event. All 15 patients (100%) had microscopically identifiable debris in the filters, whereas gross inspection detected visible debris only in 5 patients (33.3%). Histological analysis revealed various types of structural components in an advanced atheromatous plaque, including fragments of fibrous cap, calcified plaque, smooth muscle cells, and necrotic tissue fragment infiltrated with monocytes and macrophages.

CONCLUSIONS

Filter-type EPDs may contribute to reducing the risk of CAS-related embolic events by capturing micro-debris even when gross inspection of the recovered filter shows no visible debris in the device.

Meta-Analysis of Perioperative Stroke and Mortality in Transcatheter Aortic Valve Implantation

Transcatheter aortic valve implantation (TAVI) is a rapidly evolving safe method with decreasing incidence of perioperative stroke. There is a void in literature concerning the impact of stroke after TAVI in predicting 30-day stroke-related mortality. The primary aim of this meta-analysis was to determine whether perioperative stroke increases risk of stroke-related mortality after TAVI. Online databases, using relevant keywords, and additional related records were searched to retrieve articles involving TAVI and stroke after TAVI. Data were extracted from the finalized studies and analyzed to generate a summary odds ratio (OR) of stroke-related mortality after TAVI. The stroke rate and stroke-related mortality rate in the total patient population were 3.07% (893 of 29,043) and 12.27% (252 of 2,053), respectively. The all-cause mortality rate was 7.07% (2,053 of 29,043). Summary OR of stroke-related mortality after TAVI was estimated to be 6.45 (95% confidence interval 3.90 to 10.66, p <0.0001). Subgroup analyses were performed among age, approach, and valve type. Only 1 subgroup, transapical TAVI, was not significantly associated with stroke-related mortality (OR 1.97, 95% confidence interval, 0.43 to 7.43, p = 0.42). A metaregression was conducted among females, New York Heart Association class III/IV status, previous stroke, valve type, and implantation route. All failed to exhibit any significant associations with the OR. In conclusion, perioperative strokes after TAVI are associated with >6 times greater risk of 30-day stroke-related mortality. Transapical TAVI is not associated with increased stroke-related mortality in patients who suffer from perioperative stroke. Preventative measures need to be taken to alleviate the elevated rates of stroke after TAVI and subsequent direct mortality.

MDCT has the potential to predict percutaneous coronary intervention outcome in swine model: microscopic validation

BACKGROUND

Volumes and sizes of dislodged coronary microemboli vary during PCI so their effects at the left ventricular (LV) and cellular levels cannot be quantified. Furthermore, biopsy for tissue characterization is not an option in PCI patients.

PURPOSE

To characterize and validate microinfarct size, LAD territory where microinfarct were found using multidetector computed tomography (MDCT), histochemical staining and microscopy as a function of microemboli volumes and to scale the effects of microemboli volumes on LV function.

MATERIAL AND METHODS

Under X-ray guidance, a 3F catheter was inserted into LAD coronary artery of 14 pigs for delivering 16 mm(3) or 32 mm(3) of 40-120 μm microemboli. MDCT imaging/histochemical staining/microscopy were performed 3 days later and used to characterize regional and global structural and functional changes in LV by threshold/planimetric methods.

RESULTS

MDCT and ex-vivo methods were able to quantify microinfarct size and LAD territory where microinfarct was found as a function of volumes. However, MDCT and histochemical staining significantly underestimated microinfarct size and territory where microinfarct was found compared with microscopy. MDCT demonstrated the functional changes and showed a moderate correlation between LV ejection fraction and microinfarct size (r = 0.53). Microscopy provided higher spatial resolution for measuring islands of necrotic cells, which explains the difference in measuring structural changes.

CONCLUSION

MDCT showed the difference in microinfarct size and LAD territory as a function of microemboli volumes and scaled the changes in LV function. This experimental study gives clinicians a reference for the effects of defined microemboli volumes on myocardial viability and LV function and the under-estimation of microinfarct on MDCT.

Evaluation of the acute effects of distal coronary microembolization using multidetector computed tomography and magnetic resonance imaging

The purpose of this study was to test the potential of clinical imaging modalities, 64-slice multidetector computed tomography (MDCT) and 1.5T magnetic resonance imaging (MRI) for qualitative and quantitative evaluation of acute microinfarcts and to determine the effects of <120 μm microemboli on left ventricular function, perfusion, cardiac injury biomarkers, arrhythmia, and cellular and vascular structures. Under X-ray fluoroscopy, 40-120 μm (16 mm(3) ) microemboli were delivered to embolize the left anterior descending (LAD) coronary artery of nine pigs. MDCT/MRI were performed at 72 h in a single session. Microinfarcts were visible in six of nine animals on delayed contrast-enhanced MDCT/MR images but measurable in all animals using semiautomated threshold methods. Other MDCT and MRI sequences demonstrated decline in left ventricular ejection fraction, regional strain and perfusion in visible and invisible microinfarcted regions. Microemboli caused significant elevation in cardiac injury enzymes and arrhythmias. Various sizes of microinfarcts appeared microscopically as distinct aggregates of macrophages replacing myocardium. Semiautomated threshold methods are necessary to measure and confirm/deny the presence of myocardial microinfarcts. This study offers support for alternative applications of MDCT/MRI in assessing clinical cases in which microemboli <120 μm escape protective devices during percutaneous coronary interventions. Although microembolization resulted in no mortality, it caused left ventricular dysfunction, perfusion deficit, cellular damage increase in cardiac injury enzymes, and arrhythmias.

MRI study on volume effects of coronary emboli on myocardial function, perfusion and viability

BACKGROUND

Coronary filtration devices showed inadequate protection during PCI due to the inability to filter microemboli <120 μm in diameter. The purpose of this study was to determine the impact of two volumes of <120 μm microemboli on LV function, perfusion and viability using magnetic resonance imaging (MRI).

METHODS

Under X-ray guidance, pigs (n = 18) received two different volumes (16 mm(3) or 32 mm(3)) of 40-120 μm microemboli (intracoronary). At 3 days, regional myocardial perfusion and LV function were assessed using first pass perfusion and cine MRI. Viability MRI was performed in beating and non-beating hearts to delineate microinfarcts and compare with histochemical triphenyltetrazolium chloride stain, using semi-automatic threshold method. Histology and cardiac injury enzymes were used to confirm the presence of microinfarcts and characterize cellular and vascular changes.

RESULTS

Microinfarcts were visible as enhanced specks on DE-MRI in all animals that received 32 mm(3), but only two-third of the animals that received 16 mm(3), volume. The decline in ejection fraction and increase in LV volumes and microinfarcts were volume dependent. Regional perfusion and contractility were significantly reduced in the LAD territory compared with remote myocardium. Histology showed apoptosis, edema, inflammation and vascular thrombosis.

CONCLUSIONS

Microemboli of <120 μm have deleterious effects on LV function, perfusion and viability and the effects are dependent on microemboli volume. Microinfarct visualization is crucial to ensure that myocardial dysfunction is related to dislodged microemboli and not only to pre-procedural stunning or hibernation. This noninvasive MRI method may help in evaluating the effectiveness of coronary filtration devices in protecting myocardium from microemboli.

Particle formation and risk of embolization during transseptal catheterization: comparison of standard transseptal needles and a new radiofrequency transseptal needle

Objective

Anecdotally, the Brockenbrough transseptal needle generates plastic particles through a process of skiving (shaving off particles), when advanced through the dilator and sheath. This study was performed to assess particle creation by the Brockenbrough needle during transseptal catheterization. We explore strategies that may reduce this phenomenon, including use of the Brockenbrough stylet and a radiofrequency transseptal needle.

Method

In vitro simulations of transseptal catheterization were performed using Brockenbrough transseptal needles and a new radiofrequency transseptal needle. Particles that were created during advancement of transseptal needles through the sheath and dilator were collected and analyzed. Particles in the visible range of 50 μm to 4 mm were identified using a light microscope, whereas particles in the sub-visible, yet clinically relevant range of 10 to 50 μm, were counted using a light obscuration method.

Results

All simulated procedures using the Brockenbrough transseptal needles, with or without a stylet, generated visible particles. Simulated procedures with the radiofrequency transseptal needle generated no visible particles. A greater number of sub-visible particles were generated with the standard Brockenbrough transseptal needle (BKR-1) without stylet compared with the standard Brockenbrough needle (BRK-1) with stylet, the Brockenbrough extra sharp (BRK-1XS) needle with or without stylet, and the radiofrequency needle (NRG C1).

Conclusion

Clinically relevant particles, both visible and sub-visible, with the potential for causing embolic complications, are generated by the BRK-1 needle without stylet. Use of a stylet in the BRK-1 needle, or the BRK-1XS needle with or without stylet, appears to reduce the size and amount of particles created. The NRG C1 needle appears to eliminate visible particles and is comparable to the BRK-1 with stylet and the BRK-1XS with or without stylet in generation of sub-visible particles. Important steps can be taken to minimize the creation of particles during the advancement of the BRK-1 through the transseptal sheath and dilator.

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.

The pathogenesis and treatment of no-reflow occurring during percutaneous coronary intervention

No-reflow is one of the major causes of postinterventional rise of cardiac enzyme and myocardial infarction (MI). This complication is associated with substantial morbidity and mortality after percutaneous coronary intervention (PCI). During and after a no-reflow episode, the patient can suffer from severe chest pain, hypotension, bradycardia, hemodynamic collapse, MI, congestive heart failure, and death. Every effort should be taken to reduce the incidence of this complication. The distal embolic protection device has been shown to decrease this risk in saphenous vein graft (SVG) interventions but not in native coronaries. On the other hand, the use of glycoprotein IIb/IIIa receptor antagonists have been effective in reducing the occurrence of no-reflow during PCI of native coronaries but not during SVG interventions. The treatment of no-reflow is based on the intracoronary administrations of medications that induce maximal vasodilatation in small distal coronary vasculature. The most commonly used drugs in this setting are adenosine, nitroprusside, and verapamil. The goal of this study was to review the pathogenesis and treatment of no-reflow in patients undergoing PCI.

Coronary artery embolisation

In the setting of an acute inferior myocardial infarction undergoing primary stent implantation, we could document a macroscopic embolus moving along the right coronary artery. Coronary embolisation is a well known drawback of percutaneous coronary interventions and dedicated devices can be used in order to minimize myocardial damage. Nonetheless, unexpected macroscopic embolisation after the first manual contrast injection through a diagnostic catheter remains a possible complication and may lead to unsatisfactory results when the upstream pharmacological therapy is not appropriate.

Coronary microembolization

Atherosclerotic plaque rupture is the key event in the pathogenesis of acute coronary syndromes and it also occurs during coronary interventions. Atherosclerotic plaque rupture does not always result in complete thrombotic occlusion of the epicardial coronary artery with subsequent impending myocardial infarction, but may in milder forms result in the embolization of atherosclerotic and thrombotic debris into the coronary microcirculation. This review summarizes the present experimental pathophysiology of coronary microembolization in animal models of acute coronary syndromes and highlights the main consequences of coronary microembolization--reduced coronary reserve, microinfarction, inflammation and oxidative modification of contractile proteins, contractile dysfunction and perfusion-contraction mismatch.Furthermore, the review presents the available clinical evidence for coronary microembolization in patients and compares the clinical observations with observations in the experimental model.

Microvascular obstruction after successful fibrinolytic therapy in acute myocardial infarction. Comparison of reteplase vs reteplase+abciximab: A cardiovascular magnetic resonance study

BACKGROUND.: About one third of patients with TIMI 3 after reperfusion have evidence of microvascular obstruction (MO) which represents an independent predictor of myocardial wall rupture. This explains all efforts made to prevent MO. Magnetic resonance imaging (MRI) has proved to be particularly useful in detecting MO. The aim of this study was to evaluate with MRI if different fibrinolytic regimens in acute myocardial infarction display different effects on left ventricle (LV) volumes and ejection fraction (EF), as well as on myocardial infarct size (MIsz) and MO. METHODS.: Twenty male patients, mean age 58 years, affected by acute myocardial infarction, ten anterior and ten inferior, were treated with: full dose reteplase in ten, and half dose reteplase plus full dose abciximab (R+Abcx) in the other ten patients. In the fourth day after hospital admission, MRI STIR T2 images were used to quantify MIsz, while 2dflash cineloops were used after the injection of gadolinium, to quantify LV volumes, EF and to detect MO. RESULTS.: LV EF was higher in R+Abcx 51±10 than in reteplase 41±8. MIsz was similar in both treatment groups: however a close relationship was present between MIsz and EF in the reteplase group indicating that the greater the MIsz the lower the EF. In R+Abcx this relationship was no longer present, suggesting a protective effect of the drug on microcirculation. In fact extensive MO was present in 25% of all cases, 80% of which in the reteplase group while only 20% in R+Abcx. CONCLUSION.: R+Abcx prevents MO: compared to traditional fibrinolytic therapy it allows better LV function and most likely improved long term survival.

Mechanical thrombectomy options in complex percutaneous coronary interventions

Percutaneous coronary interventions (PCI) of thrombus-containing lesions are associated with an increased risk of acute complications and poorer long term vessel patency. Dealing with these vessels provides many technical challenges, especially with the significant risk of coronary no reflow and distal embolization. Pharmacological strategies, including intravenous and intracoronary glycoprotein IIbIIIa inhibitors reduce intracoronary thrombus propagation, improve TIMI flow and are associated with a reduction in adverse event rates. Mechanical strategies (particularly embolic protection and thrombectomy catheters) help to improve coronary blood flow and myocardial perfusion. However, their impact on clinical outcomes is less clear. The use of embolic protection devices is associated with better perfusion, blood flow, and clinical outcomes among patients undergoing saphenous vein graft (SVG) PCI. However, the role for these devices in primary PCI and native coronary artery interventions is uncertain. This study examines the current approaches to manage thrombotic lesions during PCI and reviews the evidence in support of the different mechanical thrombectomy options that are available to the interventional cardiologist.

Incidence and Management of "No-Reflow" Following Percutaneous Coronary Interventions

No-reflow is a complex condition associated with inadequate myocardial perfusion of the coronary artery in the absence of epicardial obstruction. It can occur in several settings, including percutaneous coronary intervention, especially in complex thrombotic lesions of native arteries and vein grafts and in primary angioplasty. The causes of no-reflow are not completely understood, and current treatments consist of intracoronary vasodilators, antithrombotic therapies, and mechanical devices (including aspiration thrombectomy catheters and embolic protection devices).

The no-reflow phenomenon in coronary arteries

No reflow occurs when there is inadequate myocardial perfusion of a given segment of the coronary circulation without evidence of epicardial vessel obstruction. It is a rare but clinically significant condition associated with myocardial infarction and coronary interventions. Diagnosis is usually based on clinical signs of myocardial ischemia (symptoms and/or ECG changes) combined with coronary angiography. Management can be difficult and primarily consists of intracoronary administration of vasodilators. One interesting etiology is thromboembolism and this has become the focus for new potential treatments, including distal embolic protection devices.