Cardiopulmonary support and physiology
Six-minute walk distance as parameter of functional outcome after pulmonary endarterectomy for chronic thromboembolic pulmonary hypertension

https://doi.org/10.1016/j.jtcvs.2006.10.020Get rights and content
Under an Elsevier user license
open archive

Objectives

In chronic thromboembolic pulmonary hypertension, objective data to assess the functional outcome after pulmonary endarterectomy are lacking. We studied the 6-minute walk distance in relation to the clinical and hemodynamic severity of disease, and assessed the effect of pulmonary endarterectomy on the 6-minute walk distance.

Methods

A total of 50 consecutive patients with chronic thromboembolic pulmonary hypertension were studied. Subsequently, pulmonary endarterectomy was performed in 42 patients, 35 of whom underwent a 6-minute walk distance 1 year after surgery.

Results

The mean ± standard error of the mean 6-minute walk distance was 391 ± 19 m. The 6-minute walk distance decreased in proportion to New York Heart Association functional class and correlated (all P < .0001) with mean pulmonary artery pressure (r = −0.62), cardiac output (r = 0.76), total pulmonary resistance (r = −0.75), mixed venous oxygen saturation (r = 0.77), and brain natriuretic peptide (r = −0.65). One year after pulmonary endarterectomy, the 6-minute walk distance increased from 417 ± 19 m to 517 ± 16 m (P < .0001). The change from baseline in 6-minute walk distance correlated with the changes after 1 year in New York Heart Association functional class (P < .01) and brain natriuretic peptide (r = 0.57, P < .002), and with the observed hemodynamic changes directly after pulmonary endarterectomy (change in mean pulmonary artery pressure: r = 0.52; change in cardiac output: r = 0.70; change in total pulmonary resistance r = 0.70; all P < .001). In patients with residual pulmonary hypertension after pulmonary endarterectomy, the 6-minute walk distance was significantly lower than in hemodynamically normalized patients. However, the absolute increase in the 6-minute walk distance was higher in patients with residual pulmonary hypertension (137 ± 26 m and 82 ± 20 m, respectively; P = .03).

Conclusions

The 6-minute walk distance was demonstrated to reflect the clinical and hemodynamic severity of disease in patients with chronic thromboembolic pulmonary hypertension. One year after pulmonary endarterectomy, the 6-minute walk distance had increased significantly, and the change in the 6-minute walk distance correlated with the observed clinical and hemodynamic improvement.

CTSNet classification

11
17

Abbreviations and Acronyms

BNP
brain natriuretic peptide
CO
cardiac output
CTEPH
chronic thromboembolic pulmonary hypertension
iPAH
idiopathic pulmonary arterial hypertension
mPAP
mean pulmonary artery pressure
PEA
pulmonary endarterectomy
SvO2
venous oxygen saturation
TPR
total pulmonary resistance
WSR
Wilcoxon signed-ranks

Cited by (0)

H. J. R. and M. N. vdP were supported by a nonrestricted grant from Actelion Pharmaceuticals, The Netherlands bv, Woerden, The Netherlands. P. B. received honoraria from Actelion Pharmaceuticals for lecturing at conferences. The other authors state that no conflict of interest exists.