TY - JOUR
T1 - Improvement in Coronary Blood Flow Velocity With Acute Biventricular Pacing Is Predominantly Due to an Increase in a Diastolic Backward-Travelling Decompression (Suction) Wave
AU - Kyriacou, Andreas
AU - Whinnett, Zachary I.
AU - Sen, Sayan
AU - Pabari, Punam A.
AU - Wright, Ian
AU - Cornelussen, Richard
AU - Lefroy, David
AU - Davies, D. Wyn
AU - Peters, Nicholas S.
AU - Kanagaratnam, Prapa
AU - Mayet, Jamil
AU - Hughes, Alun D.
AU - Francis, Darrel P.
AU - Davies, Justin E.
PY - 2012/9/11
Y1 - 2012/9/11
N2 - Background-Normal coronary blood flow is principally determined by a backward-traveling decompression (suction) wave in diastole. Dyssynchronous chronic heart failure may attenuate suction, because regional relaxation and contraction overlap in timing. We hypothesized that biventricular pacing, by restoring left ventricular (LV) synchronization and improving LV relaxation, might increase this suction wave, improving coronary flow. Method and Results-Ten patients with chronic heart failure (9 males; age 65 +/- 12; ejection fraction 26 +/- 7%) with left bundle-branch block (LBBB; QRS duration 174 +/- 18 ms) were atriobiventricularly paced at 100 bpm. LV pressure was measured and wave intensity calculated from invasive coronary flow velocity and pressure, with native conduction (LBBB) and during biventricular pacing at atrioventricular (AV) delays of 40 ms, 120 ms, and separately preidentified hemodynamically optimal AV delay. In comparison with LBBB, biventricular pacing at separately preidentified hemodynamically optimal AV delay (BiV-Opt) enhanced coronary flow velocity time integral by 15% (7%-25%) (P = 0.007), LV dP/dt(max) by 15% (10%-21%) (P = 0.005), and (neg)dP/dt(max) by 17% (9%-22%) (P = 0.005). The cumulative intensity of the diastolic backward decompression (suction) wave increased by 26% (18%-54%) (P = 0.005). The majority of the increase in coronary flow velocity time integral occurred in diastole (69% [41%-84%]; P = 0.047). The systolic compression waves also increased: forward by 36% (6%-49%) (P = 0.022) and backward by 38% (20%-55%) (P = 0.022). Biventricular pacing at AV delays of 120 ms generated a smaller LV dP/dt(max) (by 12% [5%-23%], P = 0.013) and (neg)dP/dt(max) (by 15% [8%-40%]; P = 0.009) increase than BiV-Opt, against LBBB as reference; BiV-Opt and biventricular pacing at AV delays of 120 ms were not significantly different in coronary flow velocity time integral or waves. Biventricular pacing at AV delays of 40 ms was no different from LBBB. Conclusions-When biventricular pacing improves LV contraction and relaxation, it increases coronary blood flow velocity, predominantly by increasing the dominant diastolic backward decompression (suction) wave. (Circulation. 2012;126:1334-1344.)
AB - Background-Normal coronary blood flow is principally determined by a backward-traveling decompression (suction) wave in diastole. Dyssynchronous chronic heart failure may attenuate suction, because regional relaxation and contraction overlap in timing. We hypothesized that biventricular pacing, by restoring left ventricular (LV) synchronization and improving LV relaxation, might increase this suction wave, improving coronary flow. Method and Results-Ten patients with chronic heart failure (9 males; age 65 +/- 12; ejection fraction 26 +/- 7%) with left bundle-branch block (LBBB; QRS duration 174 +/- 18 ms) were atriobiventricularly paced at 100 bpm. LV pressure was measured and wave intensity calculated from invasive coronary flow velocity and pressure, with native conduction (LBBB) and during biventricular pacing at atrioventricular (AV) delays of 40 ms, 120 ms, and separately preidentified hemodynamically optimal AV delay. In comparison with LBBB, biventricular pacing at separately preidentified hemodynamically optimal AV delay (BiV-Opt) enhanced coronary flow velocity time integral by 15% (7%-25%) (P = 0.007), LV dP/dt(max) by 15% (10%-21%) (P = 0.005), and (neg)dP/dt(max) by 17% (9%-22%) (P = 0.005). The cumulative intensity of the diastolic backward decompression (suction) wave increased by 26% (18%-54%) (P = 0.005). The majority of the increase in coronary flow velocity time integral occurred in diastole (69% [41%-84%]; P = 0.047). The systolic compression waves also increased: forward by 36% (6%-49%) (P = 0.022) and backward by 38% (20%-55%) (P = 0.022). Biventricular pacing at AV delays of 120 ms generated a smaller LV dP/dt(max) (by 12% [5%-23%], P = 0.013) and (neg)dP/dt(max) (by 15% [8%-40%]; P = 0.009) increase than BiV-Opt, against LBBB as reference; BiV-Opt and biventricular pacing at AV delays of 120 ms were not significantly different in coronary flow velocity time integral or waves. Biventricular pacing at AV delays of 40 ms was no different from LBBB. Conclusions-When biventricular pacing improves LV contraction and relaxation, it increases coronary blood flow velocity, predominantly by increasing the dominant diastolic backward decompression (suction) wave. (Circulation. 2012;126:1334-1344.)
KW - biventricular pacing
KW - cardiac resynchronization therapy
KW - coronary flow
KW - heart failure
KW - wave intensity
U2 - 10.1161/CIRCULATIONAHA.111.075606
DO - 10.1161/CIRCULATIONAHA.111.075606
M3 - Article
C2 - 22855569
SN - 0009-7322
VL - 126
SP - 1334
EP - 1344
JO - Circulation
JF - Circulation
IS - 11
ER -