Peripheral vascular adaptation and orthostatic tolerance in Fontan physiology.
Peripheral vascular adaptation and orthostatic tolerance in Fontan physiology.
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DOI：
10.1161/circulationaha.109.854331
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发表时间：
2009-11-03
期刊：
影响因子：
37.8
通讯作者：
Stewart J
中科院分区：
文献类型：
--
作者：
Krishnan US;Taneja I;Gewitz M;Young R;Stewart J
Fontan循环严重依赖于静脉压升高以维持有效的静脉回流。我们推测，慢性增加的体静脉压导致局部和外周血管的适应性变化，以维持心输出量，特别是在直立时。使用测量循环反应（外周和房室血流、静脉容量和微血管滤过）的技术，对9例Fontan术后患者（年龄13-24岁）和6例年龄和性别匹配的对照进行比较。研究参数：应变仪体积描记法（SPG）通过阻抗体积描记法（IPG）和头高位倾斜（HUT）测试测量外周循环功能、局部血容量分布。Fontan和对照组在几个血管室中观察到重要差异：1.小牛容量较低（中位数3.5 vs. 5.5ml/100 ml组织; p=0.005），静息静脉压（Pv）较高（13.0 vs.10.5 mmHg p=0.004）。2.腿部动脉阻力较高（32.1 vs. 22.2 p=0.03）3.微血管滤过压和水肿阈值升高。4.使用HUT时，Fontan组与对照组相比，内脏血流量未减少（分数变化+4% vs. -32% p=0.004），内脏动脉阻力未如预期增加。（分数变化+8% vs +79% p= 0.003）。静脉顺应性降低和滤过阈值升高可能是Fontan循环中维持静脉回流的适应性机制。代偿良好的Fontan受试者表现出上级立位耐受性，这是由于HUT引起的房室液移位减少和血管阻力较高。这是由于静脉僵硬度增加和内脏电容降低所致，也可能是这些患者站立时维持静脉回流的适应性机制。
The Fontan circulation is critically dependent on elevated venous pressures to sustain effective venous return. We hypothesize that chronically increased systemic venous pressures lead to adaptive changes in regional and peripheral vessels to maintain cardiac output, especially when upright. 9 post Fontan patients (age 13-24 y) and 6 age and gender matched controls were compared, using techniques to measure circulatory responses (peripheral and compartmental blood flow, venous capacity and microvascular filtration). Parameters studied: Strain gauge plethysmography (SPG) measures of peripheral circulatory function, regional blood volume distribution by impedance plethysmography (IPG) and head-up tilt (HUT) testing. Important differences between Fontan and controls were seen in several vascular compartments: 1.Calf capacitance was lower (median 3.5 vs. 5.5ml/100ml tissue; p=0.005), and resting venous pressure (Pv) higher (13.0 vs.10.5 mmHg p=0.004). 2. Higher leg arterial resistance (32.1 vs. 22.2 p=0.03) 3. Microvascular filtration pressures and threshold for edema were elevated. 4. With HUT, splanchnic flow did not reduce in Fontan vs. Controls (Fractional change +4% vs. -32% p=0.004) and splanchnic arterial resistance did not increase as expected. (Fractional change +8% vs +79% p= 0.003). Reduced venous compliance and increased filtration thresholds may act as adaptive mechanisms in maintaining venous return in Fontan circulation. Well compensated Fontan subjects demonstrate superior orthostatic tolerance resulting from decreased compartmental fluid shifts in response to HUT and higher vascular resistance. This results from increased venous stiffness and decreased splanchnic capacitance and may also be an adaptive mechanism to maintain venous return in these patients while standing.