Abstract 2801: Increased Suction Filling in Heart Failure
Background: Katz defined left ventricular (LV) suction as the phenomenon whereby the LV relaxes quicker that it can fill. This filling due to suction is associated with a fall in pressure. Because LV relaxation is slower in heart failure we hypothesised that suction would be reduced.
Patients and Methods: Forty three patients with NYHA Class III heart failure and left ventricular ejection fraction <35% underwent pressure-volume (PV) loop studies to assess baseline suction filling and the effect of inferior vena cava occlusion (IVCO). Seven subjects with structurally normal hearts were studied as controls. From the PV loops LV end diastolic pressure (LVEDP), isovolaemic relaxation time (IVRT), tau, -dp/dt and % suction filling (% of total filling occurring during the period of LV pressure decline) were derived. In a subgroup of 11 patients, Doppler transmitral and aortic flow were obtained at identical heart rates to those during PV loop acquisition to assess IVRT and Time to Peak E-wave. Bland Altman Plots were used to assess agreement between PV loop and Doppler assessments of IVRT and Time to minimum pressure (PV loop) and time to peak E wave (Echo) respectively.
RESULTS: There was excellent agreement between Doppler and PV loop indices for both parameters. The correlation coefficient between the two techniques was r=0.91 (IVRT) and r=0.86 (Time-Pmin/Time-Peak E). % suction filling was significantly higher in the patient group versus controls (43.70±3.86 vs. 13.8±3.6%; p<0.05) despite a reduced -dp/dt (-840.4±48.4 vs. -1744.1±83.9; p<0.05) and prolonged Tau (84.3±2.5 vs. 48.6±1.8; p<0.05). LVEDP was significantly higher in the patient group (19.47±1.2 vs. 8.6±1.3mmHg; p<0.05). IVRT was shorter in the patient group (132.4±4.6ms vs. 155.7±7.7; p<0.05). IVCO resulted in a decreased % suction filling (43.7±3.6 to 26.0±2.8%; p<0.05) and LVEDP (19.47±1.2 to 15.3±0.9mmHg; p<0.05), an increase in IVRT (132.4±4.6 to 168.9±5.7ms; p<0.05), but no change in -dp/dt (-840.4±48.4 to -798.3±33.7; p<0.88) or Tau (84.3±2.5 to 87.6±2.7; p<0.55).
Conclusion: Despite a reduced maximum -dp/dt, suction filling is increased in heart failure, and is due to earlier mitral valve opening. Ventricular unloading by IVCO decreases the % suction filling towards values in controls.