Patient selection:
(1) All patients must have left bundle branch block without right bundle block.
(2) The right ventricular cardioverter-defibrillator electrode is placed in the apex of the right ventricle.
Parameters:
(1) height of R spike in lead I
(2) height of S spike in lead I
(3) height of R spike in lead V1
(4) height of S spike in lead V1
R to S spike ratio in lead I =
= (height of R spike in lead I) / (height of S spike in lead I)
R to S spike ratio in lead V1 =
= (height of R spike in lead V1) / (height of S spike in lead V1)
Left ventricular capture is present if:
(1) the R to S ratio is >= 1 in lead V1
(2) the R to S ratio is < 1 in lead V1 AND the R to S ratio is <=1 in lead I
Else there is loss of left ventricular pacing (right ventricular pacing only).
where:
• Lead I only needs to be evaluated when there is a mainly negative deflection in lead V1 when there is fusion with right ventricular stimulation (Figure 4, page 972).
Performance:
• The sensitivity for detecting LOSS of left ventricular capture is 94% and the specificity is 93%.
