Impact of electrode size on unipolar and omnipolar voltage mapping in pediatric and adult atria: does size matter?
M S Van Schie, P Knops, M H C Linderhof, N L Ramdat Misier, V Yildirim, Y J H J Taverne, N M S De GrootAbstract
Background
Voltage mapping is frequently used during electrophysiological studies to identify arrhythmogenic substrates underlying arrhythmias in pediatric and adult patients with congenital heart disease. In daily clinic, bipolar electrograms are most commonly used, although omnipolar electrograms can be used to overcome directional influences affecting the bipolar peak-to-peak voltage. Unipolar electrograms are also directional independent, although they are influenced by the amount of cardiac tissue underneath the recording electrodes. It remains unknown whether these types of electrograms are influenced by the different cardiac sizes in pediatric and adult patients.
Purpose
To investigate the impact of electrode size on unipolar and omnipolar voltage mapping in pediatric and adult atria.
Methods
Intraoperative bi-atrial epicardial mapping was performed in 59 pediatric and 65 adult patients (2.8[1.0-6.4] vs 44[35-55]years). Unipolar electrograms were recorded from which omnipolar electrograms were constructed using two orthogonal electrode pairs. On average 5,231±2,229 unipolar and 15,574±7,633 omnipolar potentials were included from pediatrics compared to 8,762±2,903 unipolar and 28,647±9,532 omnipolar potentials from adults.
Results
In adults, bi-atrial unipolar voltages were larger than omnipolar voltages (5.5[4.7-6.6] vs 4.9[4.0-6.5] mV,P<0.001), while in pediatrics omnipolar voltages were larger than unipolar voltages (5.3[4.2-6.6] vs 6.8[5.5-8.4] mV, P<0.001). In both groups, median unipolar voltages linearly correlated with median omnipolar voltages (adults:R2=0.981, pediatrics:R2=0.953). Unipolar voltages were comparable between pediatrics and adults (P=0.418), while omnipolar voltages were larger in pediatrics (P<0.001). For the entire population, there was a strong inverse exponential relationship between age and the difference of omnipolar and unipolar voltages (R2=0.874).
Conclusions
The smaller cardiac size relative to the interelectrode distance in pediatrics most likely influenced the omnipolar potential voltages, resulting in larger voltages as compared to adults. Usage of this technique for voltage mapping should therefore be with caution and specific pediatric voltage cut-offs should be considered.Unipolar and omnipolar voltage mapping