Document Detail


Gas exchange detection of exercise-induced right-to-left shunt in patients with primary pulmonary hypertension.
MedLine Citation:
PMID:  11772876     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
BACKGROUND: Because of high pulmonary vascular resistance in patients with primary pulmonary hypertension (PPH), right atrial pressure may exceed left atrial pressure during exercise, resulting in a right-to-left shunt via a patent foramen ovale (PFO). This shunting would disturb arterial PCO2 and H+ homeostasis if the pulmonary blood were not simultaneously hyperventilated to compensate for the high CO2 and H+ in the shunted blood. This article first hypothesizes and then describes unique changes in gas exchange when right-to-left exercise-induced shunting (EIS) occurs. METHODS AND RESULTS: Retrospectively, the cardiopulmonary exercise tests of 71 PPH patients were studied. Criteria postulated to document hyperventilation of the pulmonary blood flow due to a right-to-left EIS were (1) an abrupt and sustained increase in end-tidal O2 with a simultaneous sustained decrease in end-tidal CO2; (2) an abrupt and sustained increase in the respiratory exchange ratio; and (3) usually, an associated decline in pulse oximetry saturation. Each patient was evaluated for a PFO with resting echocardiography. The investigators interpreting the gas exchange evidence of EIS were blinded to the echocardiographic readings. Forty-five percent of the patients had demonstrable EIS by gas exchange criteria. Almost all were also positive for a PFO by echocardiography. Using the resting echocardiograph as the reference, the sensitivity, specificity, positive and negative predictive values, and accuracy were all between 90% to 96%. CONCLUSIONS: Exercise-induced right-to-left shunting can be detected by noninvasive, cardiopulmonary exercise testing in patients with PPH.
Authors:
Xing-Guo Sun; James E Hansen; Ronald J Oudiz; Karlman Wasserman
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Circulation     Volume:  105     ISSN:  1524-4539     ISO Abbreviation:  Circulation     Publication Date:  2002 Jan 
Date Detail:
Created Date:  2002-01-04     Completed Date:  2002-04-03     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  0147763     Medline TA:  Circulation     Country:  United States    
Other Details:
Languages:  eng     Pagination:  54-60     Citation Subset:  AIM; IM    
Affiliation:
Department of Medicine, Harbor-UCLA Medical Center, Torrance, Calif 90509-2910, USA.
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MeSH Terms
Descriptor/Qualifier:
Adult
Blood Gas Analysis
Echocardiography / methods
Exercise Test
Female
Heart Septal Defects, Atrial / physiopathology*
Humans
Hypertension, Pulmonary / physiopathology*
Male
Middle Aged
Pulmonary Gas Exchange / physiology*
Sensitivity and Specificity

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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