In vasovagal syncope, the fall in blood pressure during loss of consciousness is mainly driven by reduced venous return, evidenced by falls in stroke volume, cardiac output, and heart rate.
Observational (n=18)
Is the venous or arterial system primarily responsible for the fall in blood pressure during vasovagal syncope?
In patients with vasovagal syncope, hypotension is primarily driven by reduced venous return to the heart rather than arterial vasodilation.
AIMS: In patients with vasovagal syncope (VVS), a neural reflex appears the main determinant of hypotension leading to loss of consciousness; whether hypotension is mainly due to involvement of the arterial system or the venous system remains a debated issue. The aim of the present study was to assess which of these two systems is responsible for the fall in blood pressure (BP) in patients with VVS; to this end, a haemodynamic study was carried out not only before and during loss of consciousness but also during the recovery phase. METHODS AND RESULTS: Beat-to-beat recordings of heart rate (HR), BP (volume-clamp method) and stroke volume (SV) (modelflow method), cardiac output (CO), and total peripheral resistance (TPR) were made at rest, during unmedicated tilt testing (TT) and recovery from loss of consciousness in 18 patients with a history of syncope (age 45+/-23 years) and positive response to TT. Blood pressure showed a significant fall during prodromal symptoms and a further fall at the beginning of loss of consciousness, together with a fall in SV, CO, and HR, and a slight, but significant, increase in TPR. At the beginning of recovery, BP showed a significant increase and a further increase 5 min later, together with an increase in SV, CO, and HR without significant changes in TPR. CONCLUSION: These results suggest that in VVS the fall in BP is mainly caused by reduced venous return to the heart. The arterial system does not appear to be the main determinant of the fall of BP; however, the system appears unable to make the appropriate compensatory changes.
Fucă et al. (Thu,) conducted a observational in Vasovagal syncope (n=18). Vasovagal syncope episode during unmedicated tilt testing vs. Rest and recovery phases was evaluated on Changes in blood pressure, stroke volume, cardiac output, heart rate, and total peripheral resistance. In vasovagal syncope, the fall in blood pressure during loss of consciousness is mainly driven by reduced venous return, evidenced by falls in stroke volume, cardiac output, and heart rate.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: