Background: This study examined the influence of increased cardiac size on maximal lung volumes, forced expiratory airflows, and the diffusing capacity of the lungs in heart failure (HF) patients compared with controls.
Methods and results: Forty-one HF patients of New York Heart Association (NYHA) class: Group A = class I/II (n = 26) and Group B = class III/IV (n = 15) and an equal number matched controls (CTL) were recruited. Participants underwent echocardiography, spirometry, and posteroanterior and lateral chest radiographic evaluation (RAD) for volumetric estimation of the total thoracic cavity (TTC), diaphragm, heart, and lungs. Analysis of variance demonstrated no difference between groups for TTC volume (P = .63). RAD cardiac volumes (% TTC volume) were significantly different among all groups (P < .001). Echocardiograms determined left ventricular mass was elevated in the HF groups compared with the CTL group (P < .001) with no difference between HF groups. Lung volume (% TTC volume) was reduced as a function of disease severity (P < .001). RAD measures of cardiac volume demonstrated the strongest relationship with restrictive lung alterations (t-statistic = -5.627, P < .001 and t-statistic = -4.378, P < .001 for forced vital capacity and forced expiratory volume in 1 second, respectively).
Conclusions: These results suggest cardiac size may pose significant constraints on the lungs and likely plays a major role in the restrictive breathing patterns often reported in HF patients.