Rapid changes in cerebrovascular compliance during vasovagal syncope.

IF 3.9 3区医学 Q1 CLINICAL NEUROLOGY

Clinical Autonomic Research Pub Date : 2024-06-01 Epub Date: 2024-06-26 DOI:10.1007/s10286-024-01046-z

Leena N Shoemaker, Aleena Sajid, Ronald Schondorf, J Kevin Shoemaker

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Abstract

Purpose: The compensatory mechanisms supporting cerebral perfusion throughout head-up tilt (HUT) in patients with vasovagal syncope (VVS) remain unclear. We tested the hypothesis that increased cerebrovascular compliance (Ci) and decreased cerebrovascular resistance (CVR) support cerebral blood velocity (CBV) during pre-syncope in VVS.

Methods: Finger arterial blood pressure (ABP) and right middle cerebral artery blood velocity (CBV) were recorded in 15 individuals diagnosed with VVS (n = 11 female, mean age: 40 ± 16 years, mean body mass index: 24.9 ± 4.0 kg/m²) at supine rest and during HUT (80 degree angle). Individual ABP and CBV waveforms during VVS were input into a modified Windkessel model to calculate Ci and ohmic CVR. Gosling's pulsatility index (Pi; pulse amplitude/mean CBV) was calculated.

Results: Diastolic ABP, systolic ABP, mean ABP (72 ± 11 to 51 ± 12 mmHg), and CVR decreased progressively during presyncope (all P ≤ 0.04). As expected, systolic CBV was sustained (all P ≥ 0.29) while diastolic and mean CBV (51 ± 13 to 38 ± 13 mmHg) fell during presyncope (all P ≤ 0.04). Both Ci and Pi increased during presyncope (128 ± 97 and 60 ± 41%, respectively; all P ≤ 0.049) and were positively correlated (R² = 0.79, P < 0.01). Increased Ci contributed to changes in mean CBV (P < 0.01) but decreased CVR did not (P = 0.28).

Conclusions: These data provide evidence that Ci increases during presyncope in patients with VVS and is likely involved in the maintenance of systolic CBV during a fall in diastolic CBV. However, this regulation is not sufficient to preserve CBV in the presence of such extreme and progressive reductions in ABP.

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血管迷走性晕厥时脑血管顺应性的快速变化。

目的：支持血管迷走性晕厥（VVS）患者在整个抬头倾斜（HUT）过程中脑灌注的代偿机制仍不清楚。我们对 VVS 晕厥前脑血管顺应性（Ci）增加和脑血管阻力（CVR）降低支持脑血流速度（CBV）的假设进行了测试：方法：记录 15 名确诊为 VVS 患者（n = 11 名女性，平均年龄：40 ± 16 岁，平均体重指数：24.9 ± 4.0 kg）的手指动脉血压（ABP）和右侧大脑中动脉血流速度（CBV）：24.9±4.0kg/m2）在仰卧休息和 HUT（80 度角）时的数据。将 VVS 期间的单个 ABP 和 CBV 波形输入改进的 Windkessel 模型，以计算 Ci 和欧姆 CVR。计算高斯林脉动指数（Pi；脉搏振幅/平均 CBV）：结果：在晕厥前期，舒张压、收缩压、平均 ABP（72 ± 11 至 51 ± 12 mmHg）和 CVR 逐渐下降（所有 P 均小于 0.04）。不出所料，收缩压 CBV 保持不变（所有 P 均≥0.29），而舒张压和平均 CBV（51 ± 13 至 38 ± 13 mmHg）在阵搏前下降（所有 P 均≤0.04）。Ci 和 Pi 在晕厥前均增加（分别为 128 ± 97% 和 60 ± 41%；均 P ≤ 0.049），且呈正相关（R2 = 0.79，P 结论）：这些数据证明，VVS 患者在晕厥前 Ci 会增加，并可能在舒张期 CBV 下降时参与维持收缩期 CBV。然而，这种调节不足以在 ABP 出现极度和进行性降低时维持 CBV。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Clinical Autonomic Research 医学-临床神经学

CiteScore

7.40

自引率

6.90%

发文量

审稿时长

>12 weeks

期刊介绍： Clinical Autonomic Research aims to draw together and disseminate research work from various disciplines and specialties dealing with clinical problems resulting from autonomic dysfunction. Areas to be covered include: cardiovascular system, neurology, diabetes, endocrinology, urology, pain disorders, ophthalmology, gastroenterology, toxicology and clinical pharmacology, skin infectious diseases, renal disease. This journal is an essential source of new information for everyone working in areas involving the autonomic nervous system. A major feature of Clinical Autonomic Research is its speed of publication coupled with the highest refereeing standards.