ISNVD Abstract Book

volume and higher pressure. There are proponents for both approaches. While hand injection mimics
physiological venous flow, pressure injectors are more accurate, reproducible, make some flow related
analyses quantifiable. Either or both approaches may be utilized in any case depending on the
objectives desired. There are some modern injectors that allow low-pressure administration of contrast
and perhaps such an equipment should be preferentially used.
3. Interpretation of venographic pictures. Left versus right IJV
It may seem obvious that venography of both internal jugular veins should be interpreted in the same
way. But there are some arguments favoring a different approach to the right vs. left (or: dominant vs.
non-dominant) jugular vein. Right internal jugular vein is usually bigger, its valve has longer leaflets;
left internal jugular vein is smaller and has more transversally oriented valve leaflets. Perhaps these
parameters should be taken into account while deciding if the vein assessed should be interpreted as
normal, or pathological and requiring endovascular treatment. These dilemmas will be of special
importance if the definition of pathology were based on quantitative assessment of the flow (which in
most normal individuals is asymmetric). It is important to emphasize that asymmetry between the
jugular veins itself is not pathological, however other attributes such as stenoses, need to be
considered in the context of each individual jugular vein. In terms of what is a stenosis, there is little
consensus, the authors of already published research have utilized an arbitrary definition of 50%
luminal restriction when compared to nominal diameter of the proximal vein. However, the jugular
vein stenosis in particular is more difficult to assess because of the routine dilatation of the vein
cranially to the valve. Therefore, perhaps a nominal diameter of the vein proximal to the bulb or most
dilated part of the distal jugular should be utilized.
A few other considerations that are relevant in regards the jugular veins are, that unless the
diagnostic catheter is placed at the level of the skull base/jugular foramen, one is likely to miss a
multitude of anatomical and flow related anomalies in the upper jugular vein. Additionally, if an
angled catheter is used and it is pointed medially, the injected contrast will specifically opacify
through the mastoid and condylar emissary veins the vertebral and cervical epidural plexuses
suggesting an underlying hemodynamic anomaly when none exists. Therefore, it is important that the
angled catheters are directly laterally at the level of the jugular foramen. Frequently, the transverse
process of the C1 vertebra will visibly indent the jugular vein (since the vein lies on this bony
structure) however, a balloon will inflate under minimal pressure and Valsalva maneuver will enlarge
the compressed vein during angiography or IVUS confirming this normal relationship.
4. Interpretation of venographic pictures. Jugular valve.
What should be regarded as a pathologic valve? Currently there are two ways of thinking. Firstly,
some interpret jugular valve as abnormal if a narrowing at its level is detected: using venography,
through inflating a compliant angioplastic balloon, or through intravascular ultrasound (IVUS).
Secondly, some suggest that the valve should be interpreted as abnormal only if flow disturbances are
found (no outflow through the vein, venous outflow slowed down, reversed flow direction, outflow
through collaterals, etc). Probably more research in healthy individuals is needed to solve this
problem. Such a research, however, will not be easy to perform taking into account an invasive nature
of venography.
5. Interpretation of venographic pictures. Azygous vein
There is widespread discrepancy between performance and interpretation of azygous venograms.
Firstly, there are no standards as to where exactly along the course of the azygous vein should a
contrast injection be made, any injection made in the arch is likely to miss pathology in more proximal
portions, while abdominal injections in a much smaller caliber vessel may artificially induce reverse