Right ventricular dysfunction in adult severe cystic fibrosis

Study objectives: This study sought to assess the extent of impairment of cardiac function in adult patients with end-stage cystic fibrosis (CF) and to examine the relationship between cardiovascular abnormalities and the degree of hypoxemia and hypercapnia. Design and setting: A retrospective study in a tertiary cardiac and CF center. Participants and interventions: A total of 103 adult patients with end-stage CF awaiting lung or heart and lung transplantation (mean age [± SD], 26 ± 7 years; 54 men) underwent Doppler echocardiography and arterial blood gas analysis (mean PaO₂, 54 ± 10 mm Hg; mean PaCO₂, 47 ± 8 mm Hg). The findings were compared to those of 17 healthy control subjects (mean age, 24 ± 7 years; 13 men) who had no history of cardiac or pulmonary disease. Measurements and results: All patients were in sinus rhythm with a mean tachycardia of 112 ± 18 beats/min (control subjects, 76 ± 16; p < 0.0001) and had a cardiac output of 5.3 L/min (control subjects, 4.3 L/min; p < 0.04). In the patient group, the left ventricular (LV) dimensions, systolic and diastolic function, and wall thickness were all within normal limits. The mean amplitude of long-axis excursion in patients was normal at the LV site, but that of the right ventricular (RV) free wall was significantly reduced as compared with control subjects (1.6 ± 0.4 vs 2.2 ± 0.4 cm, respectively; p < 0.001), which was found to correlate with the degree of hypoxemia (r = 0.63; p < 0.02) and hypercapnia (r = -0.68; p < 0.01). RV diastolic function, which was represented by the relative isovolumic relaxation time to cardiac cycle length, was longer in patients than in control subjects (8.7 ± 4.8% vs 5.0 ± 3.0%, respectively; p < 0.03). The pulmonary flow acceleration time (90 ± 22 vs 121 ± 34 ms, respectively; p < 0.01) and the systolic stroke distance (7.0 ± 2.2 vs 10.5 ± 1.9 cm/s²; p < 0.001) were both lower than normal. Conclusions: This study confirms the presence of significant RV systolic and diastolic dysfunction in the setting of consistent tachycardia and increased cardiac output in adult CF patients with severe disease. No specific LV abnormalities were detected in these patients.