New test to diagnose vasovagal syncope

New Test to Diagnose Vasovagal 
Syncope 
. Advait Soni, Chau Thai Nguyen , Thach 
Nguyen 
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Background 
• Current diagnosis of vasovagal syncope is by 
exclusion after all the other tests are negative. 
Other tests include CT scan of the head, 
carotid arterial Doppler and tilt table test 
which are time consuming, non-specific, costly 
and not cost effective. 
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Method 
• Patients with history of vasovagal syncope 
who arrived to the emergency room were 
enrolled. 
• The patients of the control group received the 
usual tests as indicated and the patients in the 
study group received the new Size and 
Expansion of the Femoral Vein (SEFV) of 
which the results were shown to the 
investigators. 
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Principles on the Size and Expansion of the 
Femoral Vein (SEFV) test 
• The first principle: The volume of blood going 
through the femoral artery and returning 
through the common femoral vein should be 
the same. 
• If so, in normal condition, the size of the 
femoral artery and the femoral vein should be 
the same. 
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Principles on the Size and Expansion of the 
Femoral Vein (SEFV) test 
• The second principle: In the vascular system, 
most of the circulating blood is in the veins. The 
amount of blood in the arteries is small and the 
size of the arteries does not change much due to 
vascular tone in order to keep a fairly constant 
blood pressure. If there is a need to increase 
cardiac output, the most common mechanism is 
by increasing the heart rate. 
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• 
• Figure 1 - In this figure, the vein is seen at the bifurcation 
as the femoral artery divides into the superficial and deep 
femoral arteries. 
New Non-Invasive SEFV Test 
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• 
• Figure 2. Here at the distal end of the common 
femoral artery, the coronal plane of the artery is 
seen as a single round structure which pulsates. 
Next to it is the femoral vein. The size of the 
femoral vein is at the same of the common 
femoral artery 
New Non-Invasive SEFV Test 
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• 
New Non-Invasive SEFV Test 
Figure 3. Normal expansion of the femoral vein 
to less than 2 times larger than the baseline 
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• 
Excessive Venous Pooling 
Causing Syncope 
Figure 4. Panel A. The femoral vein at its baseline. Panel B. 
The femoral vein expanded to a huge volume upon cough. The 
is the evidence of excessive pooling causing orthostatic 
hypotension. 
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• 
Venous Compartment Contraction due 
to Blood Loss, Dehydration or 
Pulmonary Hypertension 
• If the vein does not expand with cough, then 
the patient could have suboptimal venous 
capacity (e.g. secondary to dehydration or 
bleeding). The vein is barely filled with 
blood and has no extra volume to expand 
even with higher pressure from the lungs. 
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• 
Venous Compartment Contraction due 
to Blood Loss, Dehydration or 
Pulmonary Hypertension 
Figure 5. Abnormal expansion of the femoral vein: The 
vein does not change size upon cough. Either the vein is 
barely filled with blood (e.g. during bleeding) or due to 
pulmonary hypertension. 
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• 
Venous Compartment Contraction due to 
Blood Loss, Dehydration or Pulmonary 
Hypertension 
• If the SEFV is abnormal, either without 
expansion or excessive expansion, then the 
cause of syncope would be due to volume 
contraction or orthostatic hypotension. 
There is no functional vasovagal syncope 
here. 
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• 
RESULTS 
• 20 patients were enrolled from June 2015 to 
April 2016. All came with history of near 
syncope or syncope. All patients had negative 
work-up and some patients were diagnosed of 
having vasovagal syncope. 
• The results showed that 13/20 patients had 
abnormal SEFV test. All the patients with 
vague history of near syncope had normal EFV 
test. 
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• 
Conclusion 
• The patients with vasovagal symptoms 
should have the SEFV test early and if 
the results of the SEFV are normal in 
combination with a strong history of 
vasovagal mechanism, the syncope could 
be considered benign and the patient 
discharged from the hospital. Larger scale 
of clinical trial or registries of this new 
technique are needed. 
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THANK YOU 
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