Influence of Thoracic Fluid Compartments on Pulmonary Congestion in Chronic Heart Failure

Introduction: Pulmonary congestion is a common finding of heart failure (HF), but it remains unclear how pulmonary and heart blood volumes (Vp and Vh, respectively) and extravascular lung water (EVLW) change in stable HF and affect lung function.

Methods: Fourteen patients with HF (age 68 ± 11 y, LVEF 33 ± 8%) and 12 control subjects (age 65 ± 9 y) were recruited. A pulmonary function test, thoracic computerized tomographic (CT) scan, and contrast perfusion scan were performed. From the thoracic scan, a histogram of CT attenuation of lung tissue was generated and skew, kurtosis, and full-width half-max (FWHM) calculated as surrogates of EVLW. Blood volumes were calculated from the transit time of the contrast through the great vessels of the heart.

Results: Patients with HF had greater Vp and Vh (Vp 0.55 ± 0.21 L vs 0.41 ± 0.13 L; Vh 0.53 ± 0.33 L vs 0.40 ± 0.15 L) and EVLW (skew 3.2 ± 0.5 vs 3.7 ± 0.7; kurtosis 19.4 ± 6.6 vs 25.9 ± 9.4; FWHM 73 ± 13 HU vs 59 ± 9 HU). Spirometric measures were decreased in HF (percentage of predicted: forced vital capacity 86 ± 17% vs 104 ± 9%; forced expiratory volume in 1 second 83 ± 20% vs 105 ± 11%; maximal mid-expiratory flow 82 ± 42% vs 115 ± 43%). Vp was associated with decreased expiratory flows, and EVLW was associated with decreased lung volumes.

Conclusions: Congestion in stable patients with HF includes expanded Vp and Vh and increased EVLW associated with reductions in lung volumes and expiratory flows.