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Original Research: Pulmonary Vascular Disease |

Cardiopulmonary Exercise Testing Demonstrates Maintenance of Exercise Capacity in Patients With Hypoxemia and Pulmonary Arteriovenous MalformationsExercise Capacity in Hypoxemic Patients With PAVMs

Luke S. G. E. Howard, DPhil; Vatshalan Santhirapala, MBChB; Kevin Murphy, PhD; Bhashkar Mukherjee, PhD; Mark Busbridge, PhD; Hannah C. Tighe, BSc; James E. Jackson, MD; J. Michael B. Hughes, DM; Claire L. Shovlin, PhD
Author and Funding Information

From the Divisions of Cardiovascular Medicine (Drs Howard and Mukherjee), Respiratory Medicine (Drs Murphy, Hughes, and Shovlin and Ms Tighe), Clinical Chemistry (Dr Busbridge), and Imaging (Dr Jackson), Imperial College Healthcare NHS Trust; and National Heart and Lung Institute Cardiovascular Sciences (Drs Santhirapala, Hughes, and Shovlin), Respiratory Sciences (Drs Santhirapala and Hughes), and Imperial College School of Medicine (Dr Santhirapala), Imperial College London, London, England.

CORRESPONDENCE TO: Claire L. Shovlin, PhD, National Heart and Lung Institute Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, Imperial College London, Hammersmith Campus, Du Cane Rd, London, W12 0NN, England; e-mail: c.shovlin@imperial.ac.uk


Drs Howard and Santhirapala contributed equally to this work and are co-first authors.

Part of this article was presented in abstract form at the British Thoracic Society-Winter Meeting 2013, December 4-6, 2013, London, England.

FUNDING/SUPPORT: Funding was received from the European Respiratory Society (2012 Rare Disease Achievement Award to Dr Shovlin), National Institute of Health Research London (North West) Comprehensive Local Research Network; National Institute of Health Research Biomedical Research Centre Scheme; donations from patients with hereditary hemorrhagic telangiectasia; and Imperial College BSc project funds.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2014;146(3):709-718. doi:10.1378/chest.13-2988
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BACKGROUND:  Patients with pulmonary arteriovenous malformations (PAVMs) are unusual because hypoxemia results from right-to-left shunting and not airway or alveolar disease. Their surprisingly well-preserved exercise capacity is not generally appreciated.

METHODS:  To examine why exercise tolerance is preserved, cardiopulmonary exercise tests were performed while breathing room air in 21 patients with radiologically proven PAVMs, including five restudied 3 to 12 months after embolization when their PAVMs had regressed. Where physiologic matching was demonstrable, comparisons were made with 12 healthy control subjects.

RESULTS:  The majority of patients achieved their predicted work rate despite a resting arterial oxygen saturation (Sao2) of 80% to 96%. Peak work rate and oxygen consumption (V. o2) were no lower in patients with more hypoxemia. Despite higher Sao2 following embolization (median, 96% and 90%; P = .009), patients achieved similar work rates and similar peak V. o2. Strikingly, treated patients reset to virtually identical peak oxygen pulses (ie, V. o2 per heart beat) and in many cases to the same point on the peak oxygen pulse/work rate plot. The 21 patients had increased minute ventilation (V. e) for given increases in CO2 production (V. e/V. co2 slope), but perceived dyspnea was no greater than in the 12 control subjects or in the same patients before compared to after embolization comparison. Overall, work rate and peak V. o2 were associated not with oxygenation parameters but with V. e/V. co2 slope, BMI, and anaerobic threshold.

CONCLUSIONS:  Patients with hypoxemia and PAVMs can maintain normal oxygen delivery/V. o2 during peak exercise. Following improvement of Sao2 by embolization, patients appeared to reset compensatory mechanisms and, as a result, achieved similar peak V. o2 per heart beat and peak work rates.

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