The evolution of embolic protection devices

Manipulation of atherosclerotic lesions with wires, catheters, balloons, stents and other intravascular devices during invasive procedures releases are associated with small, but clinically important and discrepant, rates of procedural complications, including cerebral and myocardial ischaemic events, cranial nerve injury and access site haematoma. Embolic protection devices (EPDs) may lower the rate of ipsilateral ischaemic events during CAS and are considered by the majority of interventionists to be mandatory during CAS. Embolic protectiondevices can be divided into three distinct types based on their mechanism of operation: distal occlusion aspiration devices, distal filters and proximal occlusion aspiration devices.

The importance of these devices are discussed in articles on Radcliffe Cardiology’s website, home to a number of cardiology review journals including Interventional Cardiology Review, European Cardiology Review and Arrythmia & Electrophysiology Review. Current evidence suggests improved stroke and death outcomes in contemporary series evaluation proximal EPDs compared with earlier series employing filter-type protection. The use of EPDs has been shown to substantially reduce the risk of major adverse cardiovascular events in patients undergoing saphenous vein graft (SVG) and percutaneous coronary intervention (PCI) although the actual use of these devices in the real-world is surprisingly low. EPDs are used routinely for carotid stenting and being tested for peripheral and renal artery interventions.

Heart electrophysiology procedures which require catheters threaded to the heart also place patients at risk of embolisms. Invasive management of heart rhythm disorders by heart electrophysiology procedures including catheter ablation and device implantation has been established as the therapy of choice for most cardiac arrhythmias, and the number of patients and complex procedures has increased dramatically. An important way to promote quality in these procedures is by increasing public awareness about the importance of heart rhythm disorders. This in turn often results in increasing public resources to reduce the impact of heart rhythm disease on society.

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The importance of Fractional Flow Reserve (FFR) in Coronary Artery Disease Management

Patients with insufficient oxygen supply to the heart, or myocardial ischemia, may benefit from coronary intervention (PCI), such as stenting of partially occluded vessels. The course of treatment for patients with CAD depends on disease severity. While coronary angiography is always performed prior to PCI, it may underestimate or overestimate the severity of specific cardiac lesions. In contrast, Fractional Flow Reserve (FFR) provides a quantitative ratio of the actual blood flow in a narrowed artery, compared with the normal achievable blood flow and is more accurate in diagnosing ischemic lesions than angiography alone. Using this functional or morphological measurement, Fractional Flow Reserve (FFR) can quantify the severity of specific stenoses.

A 2012 report prepared by multiple cardiology medical societies addressed the use of FFR in appropriate use criteria for diagnostic cardiac catheterization. These appropriate use criteria recommend FFR for diagnostic evaluation of most CAD cases determined by angiography to be of intermediate, obstructive/significant or indeterminate severity. Further targeted appropriate use criteria update for coronary revascularization were launched in the same year by various societies including the ACCF, SCAI, STS, AATS, AHA, ASNC, HFSA and SCCT. Within the criteria, the use of diagnostic cardiac catheterization is recommended as an additional invasive measurement to determine the need for PCI for patients with coronary narrowing of uncertain severity.

The critical role of physiological fractional flow reserve (FFR), in guiding interventions is discussed at a number of cardiology conferences. One such cardiology conference is the European Society of Cardiology (ESC) 2014 which takes place in Barcelona this year. The ESC hosts the world’s largest and most influential cardiovascular event every year in August. Record numbers of hot line sessions and abstracts were submitted this year and the congress is on track to host the largest number of delegates in its history.

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Advances in mitral valve disease treatment

Treatment of mitral valve disease is a very common condition, affecting about 3% of the population. Recent years have seen major advances in minimally invasive mitral valve surgery and several new catheter-based techniques are being clinically evaluated. Indeed, percutaneous therapy has emerged as an option for treatment of mitral valve disease including regurgitation and prolapse for selected, predominantly high-risk patients.

Many patients with symptomatic, severe mitral regurgitation never undergo surgery due to a deemed excessive surgical risk and complete endovascular surgery is therefore an exciting alternative for these patients. Several technologies are being investigated, most of them based on long-standing surgical techniques. Over 1,000 patients have been treated worldwide with the Mitraclip system for leaflet plication, for example. This device has gained the CE mark and there has been a shift in the spectrum of candidates suitable for this technique, as recent experiences have shown that adverse mitral anatomies and functional MR patients may also benefit from this form of complete endovascular surgery and device.

An overview of recent technology for mitral heart disease can be found on Radcliffe Cardiology’s website which has a strong focus on cardiologist education. Anatomic evaluation seems crucial in order to select the most suitable patient for the procedure and cardiac computed tomography angiography is probably the best tool for patient selection. Indeed, mitral regurgitation is a complex disease with many aetiologies and pathophysiologies and therefore it seems unlikely that a single device can fix the problem. The first challenge is in fact to really understand MV disease which is why focus on education for cardiologists is so important, then a combination of techniques will be necessary for a satisfactory MR repair. Close collaboration between interventional cardiologists, cardiac surgeons, imaging cardiologists, basic scientists and the industry is essential for these technologies to progress and become a real alternative for this group of patients.

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Advances in valve replacement

Aortic valve replacement is becoming more common with almost 5,000 aortic valve replacements being carried out on the NHS in England between April 2011 and April 2012. Transcatheter aortic valve implantation (TAVI) is an established alternative to surgical valve replacement in the management of calcified severe aortic stenosis in those with co-morbidities or adverse features (advanced age, impaired left ventricular function), or in those where open surgery may be associated with unfavourable technical features, such as previous sternotomy with a patent internal mammary graft, porcelain aorta or previous thoracic radiation, rendering the operative field hostile. A large body of experience and evidence exists predominantly for two commonly used TAVI devices; namely the balloon-expandable Edwards Sapien Valve (ESV) (Edwards Lifesciences Ltd, Irvine, California, US) and the self-expanding Medtronic CoreValve (MCV) (Medtronic Inc, Minneapolis, Minnesota, US). Although the fundamental principle behind the two valves is similar, both involving a stent with three bioprosthetic cusps (leaflets) deployed within a calcified native aortic valve, the specific design features and potential indications are different. That said, studies have not shown a difference in mortality between the two valve types.

Patients may undergo cardiac catheterizationn to confirm a diagnosis of heart disease as well as treating and replacing a faulty valve.Whilst it can seem a daunting procedure for patients, it’s reassuring for them to know that cardiac catheterization has been around since the early 1940s with the advent of catheter-based interventions, pioneered by Andreas Gruentzig in the late 1970s. Since then, there has been considerable progress in the refinement and expansion of these techniques.

Continuing Education is important to keep physicians up to speed in the ever-changing world of invasive and non-invasive cardiac techniques. With this in mind Radcliffe Cardiology’s website is a good source of information for continuing education and includes many articles as well as round table discussions on TAVI and other procedures.

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Drug-eluting balloons more successful than other treament in coronary restenosis

Drug-Eluting Balloons (DEBs) are conventional semi-compliant angioplasty balloons covered with an antirestenotic drug which is released into the vessel wall during inflation of the balloon, usually at nominal pressures with a specific minimal inflation time. The active substance on the Drug-Eluting Balloons should be lipophilic enough to have a high absorption rate through the vessel wall to compensate for the short period of contact between the inflated balloon and the vessel wall itself, and to maintain a sustained effect once released.

Percutaneous treatment of complex coronary lesions, such as small-vessel heart disease, diabetes and long diffuse disease, remain hampered by suboptimal results, even with the use of drug-eluting stents (DES). The DEB is an interesting emerging device in the field of heart disease that optimises clinical outcomes in these specific lesions. The DEB may become a viable alternative treatment option for the inhibition of coronary restenosis and subsequent revascularisation, as it allows local release of a high-concentration antirestenotic drug, paclitaxel, into the coronary vessel without using a metal scaffold or durable polymers.

Several studies have already shown promising and consistent results in the treatment of in-stent restenosis. The DEB has demonstrated its added value compared with certain DES. Inspired by these results, an increasing number of studies have been started in different coronary lesion subsets to explore the value of the DEB in a broader range of lesions. It will be interesting for cardiology associates to see whether the DEB will find more indications beyond in-stent restenosis treatment. Moreover, will all DEBs offer the same added value, or will there be differences in efficacy among the DEBs produced by the various manufacturers? As was the case in the development of DES, now the puzzle pieces have to be put together for DEB. Potentially more good news on the horizon for cardiology associates.

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