Functional Characterization of Patients with Chronic Thromboembolic Disease.
BACKGROUND
Patients with chronic thromboembolic pulmonary disease (CTED) have persistent pulmonary vascular obstruction and exercise intolerance without pulmonary hypertension at rest and may benefit from pulmonary endarterectomy. However, up to now, CTED has been poorly characterized.


OBJECTIVE
This study aimed to analyze the exercise capacity and limiting factors in CTED.


METHODS
We compared right heart catheterization and cardiopulmonary exercise test results of patients with CTED [mean pulmonary artery pressure (mPAP) at rest <25 mm Hg, n = 10], chronic thromboembolic pulmonary hypertension (CTEPH, n = 31) and a control group (n = 41) presenting with dyspnea but normal pulmonary vascular imaging and excluded pulmonary hypertension.


RESULTS
Subjects with CTED show a reduced oxygen uptake [median 76/interquartile range (IQR) 22% pred.] and work rate (median 76/IQR 21 W). The work rate was significantly lower compared to control subjects (p = 0.04) but not significantly different from CTEPH patients (p = 0.66). Oxygen pulse and breathing reserve were normal. CTED subjects showed decreased end-tidal CO2 at anaerobic threshold (28.4/4.3 mm Hg), an elevated VE/VCO2 slope (42.5/23.5), breathing equivalents (EQO2 32.0/8.7, EQCO2 39.5/8.8), alveolar-capillary oxygen gradient (34.7/15.5 mm Hg) and capillary end-tidal carbon dioxide gradient (8.8/5.7 mm Hg) compared to control subjects (p < 0.001). The degree of limitation was similar to that in CTEPH.


CONCLUSIONS
Despite an mPAP of <25 mm Hg, subjects with CTED show objective functional impairment and similar limitations to patients with CTEPH. Functional limitation is characterized by gas exchange disturbance and ineffective ventilation.
Department of Internal Medicine, Medical Mission Hospital, Academic Teaching Hospital, Wx00FC;rzburg, Germany.
Matthias
M
Held
Philipp
P
Kolb
Maria
M
Grün
Berthold
B
Jany
Gudrun
G
Hübner
Aleksandar
A
Grgic
Regina
R
Holl
Hans-Joachim
HJ
Schaefers
Heinrike
H
Wilkens
D000368:Aged; D000369:Aged, 80 and over; D002908:Chronic Disease; D004417:Dyspnea / Q000503:physiopathology; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013923:Thromboembolism / Q000503:physiopathology*