Anisotropic conduction properties in canine atria analyzed by high-resolution optical mapping - Preferential direction of conduction block changes from longitudinal to transverse with increasing age
Anisotropic conduction properties in canine atria analyzed by high-resolution optical mapping - Preferential direction of conduction block changes from longitudinal to transverse with increasing age
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DOI：
10.1161/01.cir.0000015506.36371.0d
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发表时间：
2002-04-30
期刊：
影响因子：
37.8
通讯作者：
Ogawa, S
中科院分区：
文献类型：
--
作者：
Koura, T;Hara, M;Ogawa, S
背景-各向异性传导特性可能为重入性心律失常提供了基础。我们研究了婴儿（1 - 2个月）、幼犬（6 - 12个月）和老年犬（6 - 10岁）离体右心房结构和功能各向异性的年龄依赖性变化。方法与结果：心房组织（心外膜下小区域，2.8X4.2 mm）的组织学特征是肌纤维宽度增加，肌纤维间脂肪细胞浸润。Connexin43在幼犬的整个细胞表面均匀分布。而随着年龄的增长，它逐渐向细胞末端极化。激活序列通过使用电压敏感染料的高分辨率光学成像进行分析。起搏部位的激活额沿纤维方向（纵向）比沿纤维方向（横向）更快。幼犬的等时线呈“椭圆”型，在纵向和横向传播之间过渡平稳，而老年犬的等时线呈“方形”型，过渡尖锐。传导阻滞主要发生在幼犬的纵向繁殖过程中，而在老年犬的横向繁殖过程中。波前的形状和侧向解耦程度似乎决定了块体的优先方向。仅在老年犬中观察到引起极慢横向传导的之字形激活。结论-长时间具有随年龄变化的结构各向异性，块体优先方向由纵向向横向变化与波前构型的变化有关。基于侧解耦的之字形传播将使老年人易发生多次再入和更高的房颤发生率。
Background-Anisotropic conduction properties may provide a substrate for reentrant arrhythmias. We investigated the age-dependent changes of structural and functional anisotropy in isolated right atria from infant (I to 2 months), young (6 to 12 months), and old (6 to 10 years) dogs.Methods and Results-The histology of the mapped atrial tissues (a small subepicardial area, 2.8X4.2 mm) was characterized by an age-dependent increase of myofiber width and fat cell infiltration between myofibers. Connexin43 was distributed homogeneously over the entire cell surface in infant dogs. whereas it progressively polarized to the cell termini with increasing age. The activation sequences were analyzed by high-resolution optical mapping using a voltage-sensitive dye. Activation fronts from the pacing site proceeded more rapidly along fiber orientation (longitudinal) than across it (transverse). Infant dogs showed "elliptical" isochrones with a smooth transition between longitudinal and transverse propagation, whereas old dogs had a "square" pattern with a sharp transition. Conduction block occurred predominantly during longitudinal propagation in infant dogs but during transverse propagation in old dogs. The shape of the wave front and the degree of lateral uncoupling seemed to decide the preferential direction of block. A zigzag activation causing an extremely slow transverse conduction was observed only in old dogs.Conclusions-A long with the age-dependent structural anisotropy, the preferential direction of block changed from longitudinal to transverse in association with a change in the wave front configuration. A zigzag propagation based on lateral uncoupling would predispose the elderly to multiple reentry and a higher incidence of atrial fibrillation.