Splanchnic Nerve Block Mediated Changes in Stressed Blood Volume in Heart Failure

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The authors estimated changes of stressed blood volume (SBV) induced by splanchnic nerve block (SNB) in patients with either decompensated or ambulatory heart failure with reduced ejection fraction (HFrEF). The splanchnic vascular capacity is a major determinant of the SBV, which in turn determines cardiac filling pressures and may be modifiable through SNB. We analyzed data from 2 prospective, single-arm clinical studies in decompensated HFrEF (splanchnic HF-1; resting hemodynamics) and ambulatory heart failure (splanchnic HF-2; exercise hemodynamics). Patients underwent invasive hemodynamics and short-term SNB with local anesthetics. SBV was simulated using heart rate, cardiac output, central venous pressure, pulmonary capillary wedge pressure, systolic and diastolic systemic arterial and pulmonary artery pressures, and left ventricular ejection fraction. SBV is presented as ml/70kg body weight. Mean left ventricular ejection fraction was 21 ± 11%. In patients with decompensated HFrEF (n=11), the mean estimated SBV was 3,073 ± 251ml/70kg. At 30min post-SNB, the estimated SBV decreased by 10% to 2,754 ± 386ml/70kg (p=0.003). In ambulatory HFrEF (n=14) patients, the mean estimated SBV was 2,664 ± 488ml/70kg and increased to 3,243 ± 444ml/70kg (p<0.001) at peak exercise. The resting estimated SBV was lower in ambulatory patients with HFrEF than in decompensated HFrEF (p=0.019). In ambulatory patients with HFrEF, post-SNB, the resting estimated SBV decreased by 532 ± 264ml/70kg (p<0.001). Post-SNB, with exercise, there was no decrease of estimated SBV out of proportion to baseline effects (p=0.661). The estimated SBV is higher in decompensated than in ambulatory heart failure. SNB reduced the estimated SBV in decompensated and ambulatory heart failure. The reduction in estimated SBV was maintained throughout exercise. (Splanchnic Nerve Anesthesia in HeartFailure, NCT02669407; Abdominal Nerve Blockade in Chronic HeartFailure, NCT03453151).