Adjusting AV delay produced a significantly larger acute blood pressure response than VV delay adjustment (range 21 vs 4.2 mm Hg, p<0.001), with both exhibiting a curvilinear parabolic effect.
Does adjusting atrioventricular and interventricular delays improve haemodynamics in patients with cardiac resynchronisation devices for heart failure?
Adjusting AV and VV delays in cardiac resynchronisation therapy produces a predictable parabolic haemodynamic response, with AV delay optimisation providing a substantially larger benefit than VV delay.
Absolute Event Rate: 21% vs 4.2%
p-value: p=<0.001
OBJECTIVE: To assess the haemodynamic effect of simultaneously adjusting atrioventricular (AV) and interventricular (VV) delays. METHOD: 35 different combinations of AV and VV delay were tested by using digital photoplethysmography (Finometer) with repeated alternations to measure relative change in systolic blood pressure (SBP(rel)) in 15 patients with cardiac resynchronisation devices for heart failure. RESULTS: Changing AV delay had a larger effect than changing VV delay (range of SBP(rel) 21 v 4.2 mm Hg, p < 0.001). Each had a curvilinear effect. The curve of response to AV delay fitted extremely closely to a parabola (average R2 = 0.99, average residual variance 0.8 mm Hg2). The response to VV delay was significantly less curved (quadratic coefficient 67 v 1194 mm Hg/s2, p = 0.003) and therefore, although the residual variance was equally small (0.8 mm Hg2), the R2 value was 0.7. Reproducibility at two months was good, with the SD of the difference between two measurements of SBP(rel) being 2.5 mm Hg for AV delay (2% of mean systolic blood pressure) and 1.5 mm Hg for VV delay (1% of mean systolic blood pressure). CONCLUSIONS: Changing AV and VV delays results in a curvilinear acute blood pressure response. This shape fits very closely to a parabola, which may be valuable information in developing a streamlined clinical protocol. VV delay adjustment provides an additional, albeit smaller, haemodynamic benefit to AV optimisation.
Whinnett et al. (2006) studied Heart failure (n=15). Adjustment of atrioventricular (AV) and interventricular (VV) delays was evaluated on Relative change in systolic blood pressure (SBP(rel)) (p=<0.001). Adjusting AV delay produced a significantly larger acute blood pressure response than VV delay adjustment (range 21 vs 4.2 mm Hg, p<0.001), with both exhibiting a curvilinear parabolic effect.