Pacing through lateral cardiac vein
Click on the image for a larger view
ECG of pacing through lateral cardiac vein. Pacing through lateral cardiac vein was done because of prior triple valve replacement (mitral, tricuspid and aortic) which precluded trans venous right ventricular pacing. The basic rhythm is atrial fibrillation and the fifth and last beats are paced. The tall spikes before the paced QRS complexes indicates the possibility of unipolar pacing which causes tall pacing artefacts. QS complexes in lead V4-V6 indicates an activation proceeding medially form the lateral wall of the left ventricle. This is quite different from the activation seen with the basic rhythm. Another ECG showed much smaller pacing artefacts, possibly because of filter settings which could have filtered the high frequency components of the pacing artefacts, which is quite common with digital ECG machines.