Voss Frederik, Becker Ruediger, Bauer Alexander, Kraft Patrizia, Senges-Becker Julia C, Katus Hugo A, Schoels Wolfgang
Innere Medizin III, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany.
Basic Res Cardiol. 2005 Jan;100(1):22-7. doi: 10.1007/s00395-004-0493-9. Epub 2004 Oct 26.
Increased dispersion (DISP) of refractoriness (ERP) facilitates the induction of malignant ventricular arrhythmias. Accordingly, QT DISP on surface ECG, supposedly reflecting ERP DISP, has been proposed as a noninvasive marker for risk stratification. However, a comparative analysis of local ERPs and QT measurements is not available so far.
In 19 healthy dogs, standard 12 lead surface ECGs were recorded to measure QT and RR intervals. Based on these measurements, corrected QT intervals (QTc, Bazett formula) and DISP (maximum difference) of both QT and QTc intervals (QT-DISP and QTc-DISP, respectively) were calculated. Subsequently, 60 custom-made needle electrodes (12 mm long, 4 bipolar electrodes per needle, interelectrode distance 2.5 mm) were inserted into the left (LV) and right ventricle (RV). At each bipole of 14 randomly selected needle electrodes (8 LV, 6 RV) local ERPs were determined (extrastimulus technique, basic cycle length 1000 ms). Interventricular DISP of ERP (LV-RV-DISP) was defined as the difference between the longest and shortest ERP within both ventricles. Respective values were calculated for each ventricle (LV-DISP; RV-DISP). Scatter plots and correlation analysis did not reveal a significant correlation between QT, QTc, QT-DISP, QTc-DISP and any of the ERP measurements or calculations. Although not statistically significant, the closest correlation was found between QTc and mean ERP and between QTc-DISP and LV-RV-DISP.
QT measurements on surface ECG are poorly correlated with local ERPs. If anything, QT- or QTc-DISP might provide a rough estimate of interventricular, that is, global DISP of ERP. Local or even intraventricular DISP of ERP is definitely not reflected by these QT measurements.
不应期离散度（DISP）增加会促进恶性室性心律失常的诱发。因此，体表心电图上的QT离散度（QT DISP），据推测反映了不应期离散度（ERP DISP），已被提议作为风险分层的无创标志物。然而，目前尚无局部ERP与QT测量值的对比分析。
对19只健康犬记录标准12导联体表心电图，以测量QT和RR间期。基于这些测量值，计算校正QT间期（QTc，采用Bazett公式）以及QT和QTc间期的离散度（最大差值，分别为QT离散度和QTc离散度）。随后，将60根定制的针电极（长12 mm，每根针有4个双极电极，电极间距2.5 mm）插入左心室（LV）和右心室（RV）。在14个随机选择的针电极（8个左心室，6个右心室）的每个双极处测定局部ERP（额外刺激技术，基础周期长度1000 ms）。心室间ERP离散度（LV-RV-DISP）定义为两个心室内最长和最短ERP之间的差值。计算每个心室的相应值（LV-DISP；RV-DISP）。散点图和相关性分析未显示QT、QTc、QT离散度、QTc离散度与任何ERP测量值或计算值之间存在显著相关性。尽管无统计学意义，但QTc与平均ERP以及QTc离散度与LV-RV-DISP之间的相关性最为密切。
体表心电图上的QT测量值与局部ERP的相关性较差。如果有任何关联的话，QT或QTc离散度可能会粗略估计心室间，即ERP的整体离散度。这些QT测量值肯定无法反映局部甚至心室内的ERP离散度。
