Purpose: The resting inferior vena cava (IVC) collapsibility and morphology are usually used to estimate right atrial pressure (RAP). This evaluation provides useful therapeutic, functional and prognostic information as IVC collapsibility is a marker of right ventricular overload. The aim of this study was to evaluate IVC collapsibility at exercise as a marker of cardiopulmonary adaptation to exercise.

Methods: 139 consecutive patients (67 men, mean age 57 ± 16 years, mean left ventricular ejection fraction (LVEF) 61.8 ± 10.1%) underwent a semi supine symptom-limited exercise echocardiography (EE). The main indication for EE was valve disease (40 pts), unexplained dyspnea (30 pts), measurement of pulmonary artery hypertension during exercise (42 pts), hypertrophic cardiomyopathy (17 pts), and various diseases (10 pts).

Results: Two groups were defined: group 1 (63 pts) who had IVC without respiratory collapse at peak exercise and group 2 (76 pts) with preserved IVC collapse. There were no differences with respect to sex ratio (p = 0.33) or mean age (57 ± 17 vs. 56 ± 15 years, p = 0.65), but patients without respiratory collapse were more symptomatic (NYHA class 2.07 ± 0.66 vs. 1.77 ± 0.67, p = 0.029). Baseline LVEF was lower in group 1 compared with group 2 (59 ± 11% vs. 64 ± 8%, p = 0.001). However, there were no differences between groups with regard to maximal exercise level (82 ± 27 Watts vs. 88 ± 29 Watts, p = 0.2) and exercise time (7 ± 2 min vs. 7 ± 2 min, p = 0.12). In group 1, systolic pulmonary artery pressure (sPAP) at peak exercise was significantly higher (76 ± 19 mmHg vs. 49 ± 16 mmHg, p < 0.0001) compared with group 2. Collapsibility was strongly associated with cause of exercise limitation; dyspnea was the main limitation of exercise (62%) in group 1, whereas patients of group 2 stop mainly for muscular exhaustion (79%), (p < 0.0001).

Conclusion: The loss of IVC collapsibility during exercise is a frequent finding, probably reflecting the increase in RAP. Patients without IVC collapse have a higher resting and exercise systolic pulmonary artery pressure. Dyspnea at peak exercise is strongly associated with the loss IVC collapsibility. IVC collapsibility during exercise can be used as a simple surrogate marker of abnormal cardiopulmonary response.