Impact of right ventricular diastolic function on exercise tolerance in patients with chronic obstructive pulmonary disease and hypertension

Abstract

We evaluated the impact of right ventricular (RV) diastolic function on exercise tolerance in patients with chronic obstructive pulmonary disease (COPD) and hypertension (HT). Analysis of RV diastolic function showed reduced early RV filling (p<0.05) and the ratio between early RV filling (E-wave) and late RV filling (A-wave) (E/A ratio) (p=0.007), elevated E-wave deceleration time (p<0.05) and isovolumic relaxation time (p<0.05) in the COPD with HT compared to the isolated COPD patients. It indicates a more pronounced relaxation disturbances and increased RV stiffness in patients with COPD combined with HT. We found RV diastolic dysfunction in the majority of comorbid patients – 78,2%, impaired relaxation (Grade I) was the predominant grade (50.7%), pseudo-normalized (Grade II) diastolic function was determined in 27,5%. In the isolated COPD group, normal diastolic function predominated (58.1%), pseudo-normalized - was less common (12,9%). Restricted (Grade III) RV diastolic dysfunction was not registered in our patients. Among patients with COPD and hypertension significant differences (p<0.05) were found in exercise tolerance parameters between patients with normal RV diastolic function (n=15) and RV diastolic dysfunction (n=54): the 6-min walk distance - 393.2±14.61 m vs. 380.69±13.85 m; exercise-induced dyspnea (Borg scale) - 3.4±0.63 vs. 3.98±1.0; exercise-induced oxygen desaturation - 3.4±1.3 vs. 4.35±1.42%. In the isolated COPD group reliable distinctions (p<0.05) were found in exercise tolerance parameters between patients with normal RV diastolic function (n=18) and RV diastolic dysfunction (n=13): the 6-min walk distance - 402.06±17.75 m vs. 386.85±17.6 m; exercise-induced dyspnea (Borg scale) -3.22±0.65 vs. 3.92±0.95. There was no significant difference in exercise-induced oxygen desaturation between COPD patients with normal RV diastolic function and RV diastolic dysfunction. Thus, RV diastolic dysfunction contributes to exercise intolerance and exercise-induced oxygen desaturation in patients with COPD and HT.