Results
We acquired a total of 6685 measurements using 12 catheters, three for
each of the 4 models. For each catheter, a median of 107 (IQR 100-128)
measurements was taken at each of the five specific angles. The overall
correlation between measured force and real force was high with
𝜌𝑆𝑝𝑒𝑎𝑟𝑚𝑎𝑛 ≥ 0.98 for all models. The results of all
measurements are displayed in Figure 3. The mean absolute error for each
model, across the full range, was 1.29g ±0.99g for
Tacticath™, 2.87g ±2.37g for
AcQBlate® Force, 1.38g ±1.29g for
Stablepoint™, and 2.26g ±2.70g for
Smarttouch®. However, for some combinations of a
catheter, angle, and applied force, overestimation and underestimation
of the real force were higher with a maximum of 6.5g / -5.6g for
Tacticath™, 11g / -11.6 for
AcQblate® Force, 7.4g / -5.6g for
Stablepoint™, and 8.5 / -22.6g for
Smarttouch®.
In the clinical range of 10-40g, all catheters had a lower absolute mean
error with 1.19g ±0.88g for Tacticath™, 2.86g ±2.08g
for AcQBlate® Force, 1.02g ±0.77g for
Stablepoint™, and 1.52g ±1.17g for
Smarttouch® (figure 4).
In the high force range, overestimation of more than 10g was observed
for the AcQblate® Force catheter at 90°, while both
Smarttouch® and AcQblate® Force
underestimated forces by more than 10g at angles of 30° and 45°. The
Stablepoint™ catheter overestimated higher contact
forces at 0° and 30°. Finally, the Tacticath did not over- nor
underestimate forces by more than 5g at all angles.
AcQBlate® Force and Smarttouch®showed a higher variance between individual catheters (figure 3, second
and fourth row). In addition, when fitting the data using a local
estimate function (figure 3), the measurement errors of two models seem
to scatter a bit more: The residual standard errors are numerically
higher for AcQBlate® Force (14.5g) and
Smarttouch® (14.0g), compared to
Tacticath™ (12.3g) and Stablepoint™(10.1g).