Hodgkin B C, Millard R W, Nelson C V
Am J Physiol. 1977 Apr;232(4):H406-10. doi: 10.1152/ajpheart.1977.232.4.H406.
The Brody hypothesis posits that blood in the heart chambers enhances body surface potentials due to radially oriented excitation and diminishes those due to tangentially oriented excitation. Evidence supporting the hypothesis has been found in models and in dogs. The current study was performed in pigs (Sus scrofa), anesthetized with sodium pentobarbital, to determine whether the phenomenon could also be demonstrated in a species having a ventricular activation pattern distinctly different from that of dogs. Hematocrit was varied from normal 35.3 +/- 1.1% to as low as 19.8% by hemodilution and to as high as 68.0% by hemoconcentration. Surface potentials early in QRS increased and those late in QRS decreased in hemodilution experiments, while the reverse was true in hemoconcentration experiments. Total QRS duration was 38.0 +/- 0.8 ms. The first peak in resultant dipole moment magnitude, at 5.4 +/- 0.2 ms, was inversely related to blood resistivity with a linear regression correlation coefficient r = -0.76; the second peak, at 10.9 +/- 0.1 ms, was directly related, r = 0.52; and the third peak, at 17.5 +/- 0.2 ms, was directly related, r = 0.89. When interpreted in accordance with the Brody hypothesis, changes in body surface potentials and in resultant dipole moment were consistent with radial excitation of the apical septum, ill-defined orientation of free ventricular wall excitation, and tangential excitation of basal left ventricle and septum.
布罗迪假说认为，心腔内的血液由于径向取向的兴奋而增强体表电位，而由于切向取向的兴奋而降低体表电位。在模型和狗身上已发现支持该假说的证据。本研究在戊巴比妥钠麻醉的猪（Sus scrofa）身上进行，以确定在心室激活模式与狗明显不同的物种中是否也能证明这一现象。通过血液稀释使血细胞比容从正常的35.3±1.1%变化至低至19.8%，通过血液浓缩使其高达68.0%。在血液稀释实验中，QRS早期的体表电位增加，QRS晚期的体表电位降低，而在血液浓缩实验中则相反。QRS总持续时间为38.0±0.8毫秒。合成偶极矩大小的第一个峰值出现在5.4±0.2毫秒，与血液电阻率呈负相关，线性回归相关系数r = -0.76；第二个峰值出现在10.9±0.1毫秒，呈正相关，r = 0.52；第三个峰值出现在17.5±0.2毫秒，呈正相关，r = 0.89。根据布罗迪假说进行解释时，体表电位和合成偶极矩的变化与心尖间隔的径向兴奋、游离心室壁兴奋的不明确取向以及左心室基底和间隔的切向兴奋一致。
