White P A, Chaturvedi R R, Shore D, Lincoln C, Szwarc R S, Bishop A J, Oldershaw P J, Redington A N
Department of Paediatric Cardiology, Royal Brompton Hospital, London, United Kingdom.
Am J Physiol. 1997 Jul;273(1 Pt 2):H295-302. doi: 10.1152/ajpheart.1997.273.1.H295.
This study examines the accuracy of the conductance catheter technique and, in particular, parallel conductance [expressed as offset volume (Vc)] changes during the cardiac cycle in the human left ventricle. Two groups of patients were assessed: group 1, with an open atrial septal defect, and group 2, with an interventricular communication. In a subgroup, pre- and postoperative data were compared to assess the possible impact of shunting or anatomic considerations on our measurements. Vc is normally obtained by a saline-dilution technique previously described by Baan et al. [Vc(Baan); J. Baan, E. T. Van der velde, H. G. Debruin, G. J. Smeenk, J. Koops, A. D. Van Dijk, D. Temmerman, P. J. Senden, and B. Buis. Circulation 70: 812-823, 1984]. This does not take into account potential changes during the cardiac cycle. Four cardiac cycles were taken from the hypertonic saline washin and were divided into six equal isochrones between the maximum and minimum first derivatives of left ventricular pressure (dP/dtmax and dP/dtmin, respectively). The apparent ventricular volume was regressed against stroke volume for the corresponding cardiac cycle. The volume at the gamma-intercept corresponds to the Vc at each time interval [Vc(t)]. In group 1, there was a variation in Vc(t) during systole, but the temporal changes were quite small, on the order of 4.28% (SD = 5.18%) of total corrected end-diastolic volume (mean maximal variation of 2.60 ml). Furthermore, the value of Vc obtained at dP/dtmax was not significantly different from that obtained at dP/dtmin. For group 2 as a whole, mean Vc(Baan) did not change significantly with ventricular septal defect closure (preoperative, 8.85 +/- 11.1 ml; postoperative, 9.82 +/- 11.84 ml). Group 2 children also exhibited a systolic cyclical variation in Vc(t) similar to group 1. Finally, Vc(t) as a percentage of end-diastolic volume was no different when group 1 and group 2 were compared. We conclude that in the left ventricle, even in the presence of a left-to-right shunt, there is a small but insignificant difference in parallel conductance during ventricular ejection. The magnitude of this cyclical change does not preclude ventricular volume measurement in congenital heart disease by the conductance catheter technique.
本研究考察了电导导管技术的准确性，特别是人体左心室心动周期中平行电导[以偏移容积（Vc）表示]的变化。评估了两组患者：第1组为开放性房间隔缺损患者，第2组为室间隔交通患者。在一个亚组中，比较了术前和术后的数据，以评估分流或解剖因素对我们测量结果的可能影响。Vc通常通过Baan等人先前描述的盐水稀释技术获得[Vc（Baan）；J. Baan、E. T. Van der velde、H. G. Debruin、G. J. Smeenk、J. Koops、A. D. Van Dijk、D. Temmerman、P. J. Senden和B. Buis。《循环》70: 812 - 823，1984]。这没有考虑心动周期中的潜在变化。从高渗盐水冲洗过程中获取四个心动周期，并在左心室压力的最大和最小一阶导数（分别为dP/dtmax和dP/dtmin）之间分为六个相等的等时相。将相应心动周期的表观心室容积与每搏量进行回归分析。γ截距处的容积对应于每个时间间隔的Vc[Vc（t）]。在第1组中，收缩期Vc（t）存在变化，但时间变化非常小，约为总校正舒张末期容积的4.28%（标准差 = 5.18%）（平均最大变化为2.60 ml）。此外，在dP/dtmax处获得的Vc值与在dP/dtmin处获得的值无显著差异。对于整个第2组，平均Vc（Baan）在室间隔缺损闭合后无显著变化（术前，8.85±11.1 ml；术后，9.82±11.84 ml）。第2组儿童在Vc（t）中也表现出与第1组相似的收缩期周期性变化。最后，比较第1组和第2组时，Vc（t）占舒张末期容积的百分比无差异。我们得出结论，在左心室中，即使存在左向右分流，心室射血期间平行电导也存在微小但不显著的差异。这种周期性变化的幅度并不妨碍通过电导导管技术测量先天性心脏病患者的心室容积。
