Freitas J, Santos R, Azevedo E, Carvalho M, Boomsma F, Meiracker A, Falcão de Freitas A, Abreu-Lima C
Autonomic Unit, Sao Joao Hospital, Portugal.
Int J Cardiol. 2007 Mar 20;116(2):242-8. doi: 10.1016/j.ijcard.2006.03.052. Epub 2006 Jul 14.
Orthostatic intolerance (OI) syndromes are frequent and share symptoms like dizziness and orthostatic syncope. Their pathophysiology however seems to be different. The aim of our work was to evaluate autonomic and hemodynamic behaviour in patients with familial amyloidotic polyneuropathy and neurally mediated syncope in supine position and after acute orthostatic passive stress. We studied 12 patients with autonomic failure (group A), 12 patients with neurally mediated syncope (group B) and 16 aged matched normal controls (group C), in supine position and during the first 10 min of head-up tilt test (HUTT). Beat-by-beat blood pressure and heart rate were continuously monitored and digitised at 500 Hz. The baroreceptor alfa-index gain (vagal reflex-BRG), high frequency of RR variability (HFRR, vagal tonus) and low frequency of systolic arterial pressure variability (LFSAP, sympathetic tone) were calculated. Catecholamines, plasma brain (BNP) and atrial natriuretic (ANP) peptides were also measured. Hemodynamic data were derived and calculated by the non-invasive modelflow method. During supine position, cardiac output (CO) and stroke volume (SV) were similar in all groups. Mean arterial pressure (MAP) and BNP were higher in group A. Noradrenaline (NOR), BRG, HFRR and LFSAP were extremely low in this group. BRG and adrenaline (ADR) were higher in group B than in controls. Within the first 10 min of HUTT, there was a huge drop of CO, SV and MAP in group A, maintenance of very low levels of neurohormones and lack of autonomic function. HR, LFSAP and ADR had a higher rise at HUTT in group B compared with controls (p<0.01) but a significant decrease of BRG was noted (p<0.05). ANP or BNP did not change with tilt in any group. Different orthostatic intolerance syndromes may show important hormonal, autonomic and hemodynamic differences during supine rest and enhanced after passive orthostatism.
直立不耐受（OI）综合征很常见，且有诸如头晕和直立性晕厥等共同症状。然而，它们的病理生理学似乎有所不同。我们这项研究的目的是评估家族性淀粉样多神经病和神经介导性晕厥患者在仰卧位以及急性直立被动应激后的自主神经和血流动力学表现。我们研究了12例自主神经功能衰竭患者（A组）、12例神经介导性晕厥患者（B组）以及16例年龄匹配的正常对照者（C组），在仰卧位以及头高位倾斜试验（HUTT）的前10分钟内进行观察。逐搏监测血压和心率，并以500Hz的频率进行数字化处理。计算压力感受器α指数增益（迷走反射 - BRG）、RR间期变异性的高频成分（HFRR，迷走神经张力）以及收缩期动脉压变异性的低频成分（LFSAP，交感神经张力）。还测量了儿茶酚胺、血浆脑钠肽（BNP）和心房利钠肽（ANP）。血流动力学数据通过无创模型流方法得出并计算。在仰卧位时，所有组的心输出量（CO）和每搏输出量（SV）相似。A组的平均动脉压（MAP）和BNP较高。该组的去甲肾上腺素（NOR）、BRG、HFRR和LFSAP极低。B组的BRG和肾上腺素（ADR）高于对照组。在HUTT的前10分钟内，A组的CO、SV和MAP大幅下降，神经激素水平维持在极低水平且自主神经功能缺失。与对照组相比，B组在HUTT时HR、LFSAP和ADR升高幅度更大（p<0.01），但BRG显著降低（p<0.05）。任何组中ANP或BNP均未随倾斜而改变。不同的直立不耐受综合征在仰卧休息时可能表现出重要的激素、自主神经和血流动力学差异，且在被动直立后差异更加明显。
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