The question is often asked: is intravascular ultrasound (IVUS) necessary in a deep venous practice? Stephen Black writes that it was certainly a question that he had asked when initially building his practice. The answer predominantly seemed to be that it was expensive and you could see what you needed with venogram; IVUS was a nice toy but not really needed.
I did, however, use IVUS from the very beginning of my practice and would now argue that it is an essential tool in any comprehensive service and is undoubtedly necessary.
It is absolutely clear, and the recently presented VIDIO data from Paul Gagne has confirmed this, that IVUS improves diagnostic accuracy. It is essential to use IVUS in patients with complex chronic venous insufficiency in whom traditional axial imaging or venography has not demonstrated obstruction to ensure pathology is not missed. The VIDIO trial has shown a clear increase in pick up rate for pathology in patients with chronic leg ulcers where venography was considered normal.
Treatment of venous disease is essentially binary: treatment works or it does not. There is rarely a happy medium of improvement without a blocked stent if the technical placement of the stent is not perfect. To this end IVUS adds value, not only in improving accuracy of stent placement but also in ensuring that no diseased segment of vein is missed. It is of course true that a skilled and experienced interventionalist will be able to see the confluence and demonstrate inflow vessels by using a variety of manoeuvres such as valsalva to ensure that anatomy is demonstrated. However, IVUS significantly improves both the accuracy of these assessments, and is repeatable.
The added advantage of being able to repeatedly use IVUS to image the vessels and the placed stents multiple times is often overlooked. It is not a “one-off” device. In this respect the comparator is with dynamic CT scanning at the end of a procedure. It of course gives good detail and will tell you whether you have an adequately expanded stent, but if there is an issue that needs correction it is not repeatable.
IVUS is critical in the assessment of inflow and, in particular, to ensure that there is an adequate area to place a stent at the confluence of the femoral vein and profunda vein in patients where stent extension below the ligament is required. Failure to properly treat this area by either leaving residual disease or gating the inflow from the profunda is a frequent cause of early stent failure.
Ultimately, effective treatment is a combination of cumulative data and decisions built on accurate preoperative planning and intraoperative imaging. IVUS plays an essential role in providing crucial information at all stages.
In this age (and as the latest EVAR trial publications have identified) we can not continue to ignore the effects of long-term radiation damage on both ourselves and our patients. It is clear that the routine use of IVUS reduces radiation exposure by avoiding additional venograms and contrast runs (one of the biggest contributors to total radiation dose) and clearly this dose is increased by the addition of a dynamic CT at the completion of a procedure. By using IVUS, venograms and contrast runs can be reduced to a minimum (and in some cases eliminated altogether) thus benefitting both the patient and the operator by reducing radiation exposure.
The use of IVUS is fundamental in improving outcomes in chronic patients in my practice.
We do, however, need to demonstrate this by moving beyond what is ultimately still opinion and anecdote by providing suitable research driven towards clearly answering questions to justify the use of IVUS in venous practice.
Some of this will be provided by the ongoing IDE registry data being provided by the VIRTUS study and of course the pending ABRE study, both of which include IVUS. In addition, we need to provide data from both supporters and opposers of IVUS to justify these respective positions. Ultimately, we will only develop this field appropriately by answering these questions in a rigorous fashion.
This evidence base will help to ensure that we answer adequately the question: is IVUS necessary?
Stephen Black is at Guy’s and St Thomas’ Hospital, London, UK