BACKGROUND: The 6-min walk test (6MWT) is commonly performed to assess functional status in patients with chronic thromboembolic pulmonary hypertension. However, changes in heart rate and oxygen saturation (SpO2) patterns during 6MWT in patients with chronic thromboembolic pulmonary hypertension remain unclear.
METHODS: Thirty-one subjects with chronic thromboembolic pulmonary hypertension were retrospectively evaluated to examine the relationships between the change in heart rate (?heart rate), heart rate acceleration time, slope of heart rate acceleration, heart rate recovery during the first minute after 6MWT (HRR1), change in SpO2 (?SpO2), SpO2 reduction time, and SpO2 recovery time during 6MWT, and the severity of pulmonary hemodynamics assessed by right heart catheterization and echocardiography.
RESULTS: Subjects with severe chronic thromboembolic pulmonary hypertension had significantly longer heart rate acceleration time (144.9 ± 63.9 s vs 96.0 ± 42.5 s, P = .033), lower ?heart rate (47.4 ± 16.9 vs 61.8 ± 13.6 beats, P = .02), and lower HRR1 (13.3 ± 9.0 beats vs 27.1 ± 9.2 beats, P < .001) compared to subjects with mild chronic thromboembolic pulmonary hypertension. Subjects with severe chronic thromboembolic pulmonary hypertension also had significantly longer SpO2 reduction time (178.3 ± 70.3 s vs 134.3 ± 58.4 s, P = .03) and SpO2 recovery time (107.6 ± 35.3 s vs 69.8 ± 32.7 s, P = .004) than did subjects with mild chronic thromboembolic pulmonary hypertension. Multivariate linear regression analysis showed only mean pulmonary arterial pressure independently was associated with heart rate acceleration time and slope of heart rate acceleration.
CONCLUSIONS: Heart rate and SpO2 change patterns during 6MWT are predominantly associated with pulmonary hemodynamics in subjects with chronic thromboembolic pulmonary hypertension. Evaluating heart rate and SpO2 change patterns during 6MWT may serve as a safe and convenient way to follow the change in pulmonary hemodynamics.
Persistent thromboembolic pulmonary blood circulation pressure is due to unsolved thromboembolism of pulmonary bloodstream, causing correct center incapacity and you may dying. 1–3 Disability out of take action capacity because of restricted pulmonary circulation, and therefore triggers right ventricular excess, restricted heart attack frequency, ventilation-perfusion mismatch, and practice-triggered hypoxemia, is an important feature away from persistent thromboembolic pulmonary blood pressure. Into the systematic settings, the latest six-min walking shot (6MWT) is routinely did to evaluate the functional status out of chronic thromboembolic pulmonary hypertension. 4 One of the variables within the 6MWT, the latest six-min go range (6MWD) are a good priic seriousness, functional potential, and you will emergency in people which have persistent thromboembolic pulmonary blood circulation pressure, especially in clinical samples comparing the solution to medical remedies. 5–7 However, the new fundamental power away from most other variables for example cardio-rates reaction otherwise oxygen desaturation-resaturation patterns from inside the for every single state condition from chronic thromboembolic pulmonary blood circulation pressure remains unsure.
Variables derived from the 6MWT (other than the 6MWD) have been investigated in subjects with chronic respiratory diseases. Abnormal heart rate recovery at 1 min (HRR1), which is the reduction in fetlife price heart rate at 1 min after exercise, is known to be a strong predictor of pulmonary hypertension in idiopathic pulmonary fibrosis 8 and clinical worsening in pulmonary arterial hypertension (PAH). 9 Impairment in the heart-rate response during the 6MWT, also known as a chronotropic response, has been considered to predict 6MWD in idiopathic and nonidiopathic PAH. 10 Furthermore, oxygen saturation (SpO2) change patterns during the 6MWT in subjects with COPD were reported to predict peak exercise and air flow limitations. 11 Regarding subjects with chronic thromboembolic pulmonary hypertension, one recent report described that exercise-induced desaturation during the 6MWT was observed in operable chronic thromboembolic pulmonary hypertension before pulmonary endarterectomy (PEA). And that heart rate during the 6MWT reserve [(peak heart rate ? resting heart rate)/(220 ? age ? resting heart-rate response)] was associated with pulmonary vascular resistance 1 y post PEA. 12 Thus, additional parameters of the 6MWT, such as heart rate and SpO2 change patterns, might have the potential to reveal more precise physiological states of chronic thromboembolic pulmonary hypertension. However, the confounding factors of chronic thromboembolic pulmonary hypertension, in addition to its pathophysiology, should also be considered (eg, oxygen flow, pulmonary vasodilator, PEA, and deconditioning).