Commentary

We need to reassess our primitive understanding of the venous system


 

If one includes the entire spectrum of venous disease, it is a more common pathology than peripheral arterial disease. The financial impact of venous disease is substantial. Why, then, has it taken so long to generate enthusiasm for venous disease of the femorocaval and subclaviocaval segments? For years, the endovascular management of venous disease used technology and techniques borrowed from the arterial space; although results were encouraging, it is clear that they varied widely and continue to do so. Management of these vascular beds is very reminiscent of the barrage of devices we have thrown at the superficial femoral artery.

Dr. Jean Bismuth is an associate professor of surgery and associate program director, Houston Methodist Hospital.

Dr. Jean Bismuth

In peripheral arterial disease, there have been much education and research focused on understanding atherosclerosis and its interaction with arterial devices. However, the paucity of investigation and enlightenment in the venous domain is evident when a literature search is performed. Certainly there are data from Comerota et al. showing an increased amount of collagen in the walls of chronically diseased veins. While this is a reasonable start, it is not sufficient data on which to build an entire treatment paradigm. Just like peripheral arterial disease, venous pathology presents in a continuum. Without an in-depth appreciation of the variability of those presentations, it is difficult to envision targeted therapies.

Although vendors have recently engaged in the development of venous-specific devices, it is in great part grounded in expert opinion rather than in hard data. The Medicare Evidence Development & Coverage Advisory Committee has made it known that we need more evidence on the efficacy of all venous procedures. Peter Gloviczki, MD, a vascular surgeon at Mayo Clinic, in Rochester, Minn., put it succinctly in an issue of Venous News: “We need to focus on venous research and never forget that whoever owns research owns the disease. We must continue innovation and collaboration, with other venous specialties and with industry.” Truth be told, there doesn’t seem to be much fascination with comprehension of the disease, but there appears to be an enormous drive from a variety of specialties to do procedures.

In July 2015, Gerard O’Sullivan, MD, wrote of a multidisciplinary group in Europe established to develop some standardization in venous stenting guidelines. He describes a “need for consistent guidelines for preoperative imaging, follow-up, anticoagulation duration and type, stent diameter, length into the inferior vena cava and lower end in relation to the internal iliac vein/external iliac vein.” I concur, that this would be utopic. I have not come across such guidelines to date.

Current basic science research focuses on pathologic considerations of venous thrombosis, including the consequences related to mechanical behavior of the venous wall in those conditions. In our group’s opinion, these considerations are elemental in determining the next steps in the research paradigm. What determines the remodeling of a vein, with or without intervention? How does a stent influence remodeling? Not surprisingly there are numerous questions that remain unanswered.

Translational investigation has provided insight into innovative ways to use computed tomography and magnetic resonance imaging. The ability to stage venous disease noninvasively could have a profound impact on how and why we manage the pathology. Additionally, knowing what the pathology looks like and potentially behaves like has the potential to promote more appropriate therapies. Intravascular ultrasound is well described by users and essential to the management of venous disease as it allows us to visualize and appreciate the pathology being treated in real time.

IVUS, though, is primarily used in the context of delivering a therapeutic tool as well as being invasive. Until recently, we have not been able to bring the power of cross-sectional imaging into the operative space. Our group has published on the use of multimodal imaging techniques such as magnetic resonance venography and fluoroscopic image fusion, which can potentially guide future interventions and optimize therapeutic decision-making.

Ultimately, we believe that diseased veins behave differently than arteries do. Therefore, managing veins with tools meant for another space is likely not ideal. Many venous interventions use arterial devices that are not optimized for venous pathologies and underline the fact that we need to continue to develop tools specifically designed for the venous space. The ATTRACT (Acute Venous Thrombosis: Thrombus Removal With Adjunctive Catheter-Directed Thrombolysis) trial has been extremely impactful in the treatment paradigm of venous thrombosis. Although the results remain heavily debated and, on some level, contested, it is a critical trial and should – in many ways – serve as an example of the good research being executed in venous disease.

A quote many have attributed to Albert Einstein says: “The one who follows the crowd will usually go no further than the crowd. Those who walk alone are likely to find themselves in places no one has ever been before.” We have an opportunity to be more enlightened with respect to central venous therapies; let’s not act like lemmings and follow one another off the cliff.

Dr. Bismuth is an associate professor of surgery and associate program director, Houston Methodist Hospital. He reported that he had no relevant disclosures.

References

Comerota AJ et al. 2015 May. Thromb Res. 135(5):882-7.

Vedantham S et al. 2017 Dec 7. N Engl J Med. 377(23):2240-52.

O’Sullivan G 2015 Jul. Endovascular Today.14;7:60-2.

Gloviczki P 2017 Apr. Venous News.1:8.

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