In the historic 50th anniversary year of the first angioplasty performed by Charles Dotter in 1964, Duncan Ettles, consultant Radiologist Hull and East Yorkshire Hospitals NHS Trust, honorary clinical professor in Radiology University of Hull, and president of the British Society of Interventional Radiology (BSIR), tells Interventional News how angioplasty is still the technique that underpins so many procedures undertaken by interventional radiologists. “Angioplasty was the simple spark that has evolved in to a wide armamentarium of techniques that can be used in the vascular tree,” he says.
“Angioplasty is the fundamental technique that underpins a lot of what we do in interventional radiology. With regard to the use of balloon angioplasty, when Charles Dotter went from using catheters from their original diagnostic use to demonstrating that they could be tools for therapeutic intervention, this was really the birth of interventional radiology as we now know it. The genesis of angioplasty led to all of the other things that we recognise in modern interventional therapy. As it stands 50 years later, the technique has broad applications in terms of peripheral vascular disease and has fundamentally altered the treatment of aortoiliac disease (with or without stenting) and the interventional treatment of critical limb ischaemia. In the UK, critical limb ischaemia has been flagged up as a very important disease entity and there is currently a major focus on raising awareness of the condition and developing strategies to reduce amputation rates.
A recent calculation has suggested that some 50 million angioplasties in all have been performed since that first angioplasty in 1964, which is a pretty impressive total. So it still has a very important place, but is clearly also supplemented by many additional techniques including stenting and more recently, the use of drug-eluting technology.
When we talk about advanced angioplasty, and that would involve stenting, territories in which it is widely used would include the carotid vessels and increasingly the visceral arteries as well. The use of angioplasty and stenting has then morphed to primary stenting and the use of covered stents with further evolution culminating in the introduction of abdominal and thoracic endovascular aneurysm repair.
So angioplasty was the simple spark that allowed the evolution of a wide armamentarium of techniques that can be used in the vascular tree. Whereas, in the beginning, we could only treat large vessels, because of the progressive miniaturisation of devices, we can now treat virtually any vascular territories down to vessels that are less than 2mm in diameter. The scope of treatment has come to involve vascular territories that previously could not be considered for intervention. It is also important to remember that non-vascular intervention such as hepatobiliary work, vertebroplasty and some types of interventional oncology share many of these basic techniques. They are also continuing to rapidly expand and increase treatment options in modern healthcare.
What we know about angioplasty:
• We know that angioplasty is a procedure with a high technical success, high efficacy, and low complications rate.
• We understand that the use of angioplasty in certain arterial locations is better than in others and we know that restenosis remains a major problem after the technique.
• We know that angioplasty is a technique that continues to evolve, and we have seen significant technical developments such as the use of drug-eluting balloons and drug-eluting stents.
Research questions that still remain
We still do not completely understand the best strategies to deal with restenosis. We have tackled this problem using mechanical devices, such as stents, but we know that there are also problems with in-stent restenosis. Over the years, we have seen attempts to use other methods, such as cryotherapy, to address this issue. However, restenosis remains the Achilles’ heel of endovascular intervention and we need to know more about the fundamental cellular responses of different arteries to angioplasty. The fact that all arterial beds do not react in the same way means that there are more complex responses taking place than we still understand.
Secondly, what we have struggled to understand is the best patient selection for the procedure, and at the end of the day, it is selecting the appropriate patients for a given treatment that will offer the best guarantee of success. A proportion of the failures that result from angioplasty, and/or stenting, undoubtedly relate to inappropriate patient selection.
Plain old balloon angioplasty vs. drug-elution
There are certain indications and applications for which plain old balloon angioplasty seems to work very well, but in other areas, there is increasing evidence to suggest that the use of additional devices, and more recently, the use of drug-eluting balloons and drug-eluting stents may improve patency and clinical outcomes. However, as yet, we do not have the definitive randomised information with large enough numbers of patients to confirm that these strategies offer a long-term improvement in patient outcomes. Further research will determine whether the improved short-term patency data translates into improved long-term clinical success rates.
In many respects , we still do not understand what the optimum angioplasty technique is and there are fundamental aspects of the procedure that have never been clearly established ,such as selection of the appropriate balloon size; inflation times and the best medical therapy after the procedure. Most operators will work along broadly similar lines, but there are important differences in practice over what constitutes an angioplasty. That may be one of the contributing reasons why different trials have different outcomes when measuring the effects of angioplasty as there are many potential variables. In my opinion, the different basic principles of these techniques are still incompletely understood.
There is a bit of a post code lottery when it comes to critical limb ischaemia
The introduction of interventional radiology techniques has saved countless lives and countless limbs. It is incredibly important that we continue to push minimally invasive intervention, particularly for patients who present with critical limb ischaemia, where we can make a big impact in trying to reduce amputation rates.
This is something that is currently exercising the attention not only of clinicians but many others including an All Party Parliamentary Group which has flagged up the importance of providing adequate services for vascular disease. This is an extremely important area where we must strive to improve the provision of interventional radiology services and have enough trained people to actually cope with the workload. So our objectives are to continue to develop and optimise the best treatment strategies, and strive to improve the provision of interventional services. Looking across the UK, there is evidence to confirm that services are not uniform. There is a bit of a post-code lottery for patients with critical limb ischaemia. One important contributor to this problem is that patients may be referred too late from primary care at a stage when the window of opportunity for endovascular treatment may have been missed. We still have a lot to do to educate the wider medical body and publicise the important role that interventional radiology has in potentially reducing rates of amputations.
What does interventional radiology need to do to survive another 50 years?
I think there needs to be continuing development in training curricula, and this is taking place. As interventional radiology continues to evolve as a specialty, it may be that the old model of interventional radiologist coming from diagnostic radiology and then taking up intervention as a subspecialty needs to change to a more focused approach to training in intervention right from the start. What is most important is that proper training is undertaken and we have to ensure that the highest standards of training are met. In the years to come, it may be that there are different pathways and structures of training for that. At the moment there is a very clear pathway for training through the Royal College of Radiologists with the guidance of the BSIR as a special interest group.
We also need an increase in the number of interventional radiologists who are undertaking these procedures. We know from recently conducted national surveys that we are probably deficient to the tune of about 200–250 consultant interventional radiologists in England in order to preserve the joined up 24/7 services that we would all like to see.
Interventional radiologists also must continue to be engaged clinically, that is fundamentally important for further development of the specialty and to ensure the highest standards of clinical care
Plans for the BSIR
Today, the BSIR is a society that engages with multiple other regulatory bodies to comment on and provide guidance with regard to policy development in healthcare. We have seen a major evolution in the management of conditions such as obstetric haemorrhage and gastrointestinal haemorrhage that are now managed using interventional radiology, but we have to keep pushing to ensure that we provide modern interventional care to patients right across the country. One of my major commitments as BSIR president is to continue to make the case for a significant increase in the numbers of interventional radiologists training in the UK and to change the training syllabus to reflect a more clinically-based specialty.