title: "Ventilatory alternans": a left-right alternation of inspiratory airflow in humans.
abstract: In a study visualizing ventilation with hyperpolarized (3)He magnetic resonance imaging (MRI) in elite breath hold divers, the dynamic MRI images in one subject exhibited an apparent alternation of the image intensity between left and right lung. We hypothesized that the alternation resulted from alternating variations in inspiratory flow rate to left and right lungs. Analysis showed that the alternation was not due to random uncorrelated temporal fluctuations of intensity (p<0.001). The frequency of alternation was approximately 56 min(-1), suggesting a cardiac origin. Similar alternation of ventilation was confirmed retrospectively in 4 of 6 additional subjects. These observations are consistent with previous studies showing cardiogenic mixing of gas in the lung. We speculate that cardiogenic pendelluft, possibly from ballistic lateral motion of the beating heart, could cause alternating variations of inspiratory flow to the lungs.
authors.affiliation: Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, United States.
authors.forename: Yanping
authors.initials: Y
authors.lastname: Sun
authors.forename: James P
authors.initials: JP
authors.lastname: Butler
authors.forename: Massimo
authors.initials: M
authors.lastname: Ferrigno
authors.forename: Mitchell S
authors.initials: MS
authors.lastname: Albert
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Loring
mesh_terms: D062485:Breath Holding; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006371:Helium; D006801:Humans; D008168:Lung / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D012123:Pulmonary Ventilation / Q000502:physiology*; D012119:Respiration
chemical_list: D006371:Helium