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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.
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 Expansibility of the Femoral Vein (EFV) of which the results were shown to the investigators. The study group underwent the new Expansibility of the Femoral Vein (EFV) and had treatment based on its results. The EFV is the ultrasound study of the femoral vein examining its size and expansibility during strong cough. In general, the location of the femoral artery and vein to be checked is the sagittal plane immediately proximal to the bifurcation of the superficial and deep femoral artery. The size of the femoral vein is a little larger than the size of the femoral artery. If the size of the femoral vein during cough is 3 times larger than the one at baseline, the test is considered normal. If the size of the femoral vein is >3 times larger than then baseline, it is considered abnormal suggesting excessive venous pooling and syncope. If the femoral vein expands only <2 times of the baseline during cough, it is considered abnormal suggesting present or future pulmonary hypertension. If this test was done in conjunction with a right heart catheterization, then the femoral vein pressure at baseline and during cough is recorded.
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 EFV test. All the patients with vague history of near syncope had normal EFV test.
The patients with vasovagal symptoms should have the EFV early and if the results are positive in combination with a strong history, the patient could be discharged from the hospital and there was no need to do further work-up. Larger scale of clinical trial or registries of this new technique are needed.