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This Article Full Text Full Text (PDF) All Versions of this Article: 294/1/H449    most recent 00607.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Pingitore, A. Articles by L'Abbate, A. Search for Related Content PubMed PubMed Citation Articles by Pingitore, A. Articles by L'Abbate, A.

Cardiovascular response to acute hypoxemia induced by prolonged breath holding in air

¹Consiglio Nazionale delle Ricerca Institute of Clinical Physiology, Pisa; ²Department of Human Physiology, University of Pisa, Pisa; ³Cardiovascular Department, University of Messina, Messina; and ⁴Scuola Superiore Sant'Anna, Pisa, Italy

Submitted 24 May 2007 ; accepted in final form 7 November 2007

Prolonged breath hold (BH) represents a valid model for studying the cardiac adaptation to acute hypoxemia in humans. Cardiac magnetic resonance (CMR) allows a three-dimensional, high-resolution, noninvasive, and nonionizing anatomical and functional evaluation of the heart. The aim of the study was to assess the adaptation of the cardiovascular system to prolonged BH in air. Ten male volunteer diving athletes (age 30 ± 6 yr) were studied during maximal BH duration with CMR. Four epochs were studied: I, rest; II and III, intermediate BH; and IV, peak BH. Oxygen saturation (SO₂), heart rate (HR), blood pressure (BP), systemic vascular resistance (VR), end-diastolic (EDV) and end-systolic volumes (ESV), stroke volume (SV), cardiac output (CO), ejection fraction (EF), maximal elastance index (EL), systolic wall thickening (SWT), and end-systolic wall stress (ESWS) of the left ventricle (LV) were measured in all four BH epochs. Average BH duration was 3.7 ± 0.3 min. SO₂ was reduced (I: 97 ± 0.2%, range 96–98%, vs. IV: 84 ± 2.0%, range 76–92%; P < 0.00001). BP, EDV, ESV, SV, CO, and ESWS linearly increased from epochs I to IV, whereas EF, EL, and SWT showed an opposite behavior, decreasing from resting to epoch IV (all trends are P < 0.01). During prolonged BH in air, a marked enlargement of the LV chamber occurs in healthy diving athletes. This response to acute hypoxemia allows SV,CO, and arterial pressure to be maintained despite the severe reduction in LV contractile function.

diving athletes; apnea; cardiovascular system; cardiac magnetic resonance imaging