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Cardiology
Vectorcardiography
Madelon van den Heuvel BSc, Marcel van ’t Veer MSc, PhD,
Berry van Gelder PhD, Frank Bracke, MD, PhD.
Catharina Hospital Eindhoven, April 2012
Vectorcardiographic changes in the heart axis
during left ventricular pacing
Introduction
Pt 1 LAO
Pt 1 Lateral position
Pt 1 Lateral position
90º
90º
Distal
±180º
0º
0º
±180º
90º
Methods
±180º
-159º
-159º
The Frank VCG was calculated from a standard 12-lead employing the Kors
method. This method was applied in 13 CRT patients with a standard dual
unipolar or quadripolar LV-lead implanted in a coronary sinus tributary and
unipolar stimulation of each electrode. The heart axis during stimulation was
calculated from the projection of the maximum vector in the frontal,
transversal and sagittal plane. A heart axis more to the left was suggested to be
related to an electrode position more to the right, a septal heart axis to a more
lateral position and a cranial heart axis to a more caudal position. The
calculated position of the electrodes was compared with the position on chest
X-ray in two directions.
-159º
-90º
-90º
A
Cardiac resynchronisation therapy (CRT) can optimize the contraction of the
heart by left ventricular stimulation in selected patients with heart failure. One
third of the patients do not experience clinical benefit, which might be due to
suboptimal position of the left ventricular (LV) lead. The purpose of this study
was to examine whether the heart axis obtained from a vectorcardiogram
(VCG) can be helpful in localising the left ventricular stimulation site by
determining the mutual position of the stimulation electrodes of a LV-lead.
The ultimate goal is to define the optimal left ventricular stimulation site
through VCG.
B
A
Pt 2 LAO
Pt 2 Posterior position
Pt 2 LAO
90º
Results
Distal
Distal
0º
±180º
±180º
In 90 out of 93 two-dimensional VCGs the mutual position of the LV electrodes
was correctly described compared to the X-ray: a more left oriented heart axis
correlated with a position of the LV electrode to the right in the frontal plane; a
more septal heart axis correlated with a lateral position in the transversal plane
(see figure 1); a more cranial orientated heart axis correlated with a caudal
position in the sagittal plane (see figure 2).
-39º
-90º
C
D
C
Conclusion
Figure 1. The VCGs in the transversal plane (figure 1A and 1C) suggest a more lateral LV
lead position of patient 1 according the heart axis (-159º vs. -39º). This is confirmed by
the X-ray (figure 1B) showing a more lateral position of the LV lead compared to patient 2
(figure 1D) showing a posterior position.
The VCG calculated using the Kors method is an adequate tool to determine the
mutual position of the LV electrodes and might be useful to make an accurate
determination of the lead position. These findings appear to make further
analysis of the VCG worthwhile for clinical implementation as a non-invasive
technique to determine the (optimal) LV-pacing site for CRT in order to
minimize the group of non-responders.
LAO
Distal
-90º
-90º
-142º
-157º
±180º
0º
90º
±180º
0º
90º
X
Y
Figure 2A. The VCG of a patient during proximal
stimulation showing a posterior heart axis.
1. Department of Cardiology, Catharina Hospital
2. Maastricht University
Figure 2B. The VCG of a patient during distal stimulation
showing a more posterior heart axis than during proximal
stimulation, suggesting a more caudal position
contact details: [email protected]
Figure 2C. The X-ray confirms a more caudal position of
the distal electrode compared to the proximal electrode