Assessment and consequences of the constant-volume attribute of the four-chambered heart
Assessment and consequences of the constant-volume attribute of the four-chambered heart
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DOI：
10.1152/ajpheart.00249.2003
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发表时间：
2003-11-01
影响因子：
4.8
通讯作者：
Kovács, SJ
中科院分区：
文献类型：
--
作者：
Bowman, AW;Kovács, SJ
关于四腔心脏的恒定体积假说指出，心包总体积在整个心动周期中保持不变。先前的犬类研究表明，心包体积保持恒定在 5% 以内；然而，这一假设尚未使用最先进的技术在人类身上得到验证。恒定容积假说具有几个可预测的功能后果，包括心房射血分数和心室平衡容积之间的关系。使用心脏磁共振（MR）成像（MRI），我们测量了心脏恒定体积属性的有效程度，并测试了心房射血分数和心室平衡体积之间预测关系的准确性。使用 1.5-T MR 扫描仪对 11 名正常志愿者和一名先天性心包缺失的志愿者进行了成像。获得了覆盖整个心脏的短轴电影循环堆栈。心动周期分为20个间隔。对于每个切片和间隔，测量心包体积。将切片堆叠并求和，并确定每个受试者的总心包体积随时间的变化。在正常受试者中，测量心室舒张末期、收缩末期和舒张期的心室容积。正常受试者的心包体积保持在 5 +/- 1% 范围内不变；最大变化发生在收缩末期。在先天性心包缺失的受试者中，由心外膜表面定义的心脏总体积变化了 12%。 MRI 数据很好地拟合了心房射血分数和心室平衡容积之间关系的预测。在正常受试者中，四腔心脏是一个在 5 +/- 1% 范围内的恒容泵，基于恒容的模型可以准确预测以前未报告的生理关系。
The constant-volume hypothesis regarding the four-chambered heart states that total pericardial volume remains invariant throughout the cardiac cycle. Previous canine studies have indicated that the pericardial volume remains constant within 5%; however, this hypothesis has not been validated in humans using state-of-the-art technology. The constant-volume hypothesis has several predictable functional consequences, including a relationship between atrial ejection fraction and chamber equilibrium volumes. Using cardiac magnetic resonance (MR) imaging (MRI), we measured the extent to which the constant-volume attribute of the heart is valid, and we tested the accuracy of the predicted relationship between atrial ejection fraction and chamber equilibrium volumes. Eleven normal volunteers and one volunteer with congenital absence of the pericardium were imaged using a 1.5-T MR scanner. A short-axis cine-loop stack covering the entire heart was acquired. The cardiac cycle was divided into 20 intervals. For each slice and interval, pericardial volumes were measured. The slices were stacked and summed, and total pericardial volume as a function of time was determined for each subject. In the normal subjects, chamber volumes at ventricular end diastole, end systole, and diastasis were measured. Pericardial volume remained invariant within 5 +/- 1% in normal subjects; maximum variation occurred near end systole. In the subject with congenital absence of the pericardium, total heart volume, defined by the epicardial surface, varied by 12%. The predictions of the relationship between atrial ejection fraction and chamber equilibrium volumes were well fit by MRI data. In normal subjects, the four-chambered heart is a constant-volume pump within 5 +/- 1%, and constant- volume-based modeling accurately predicts previously unreported physiological relationships.