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Non-invasive monitoring of blood gas-induced changes of myocardial oxygenation using oxygen-sensitive CMR

  • Dominik P Guensch
  • Kady Fischer
  • Jacqueline Flewitt
  • Janelle Yu
  • Ryan Lukic
  • Julian A Friedrich
  • Matthias G Friedrich
Open Access
Poster presentation

Keywords

Breath Hold Breathing Maneuver SSFP Cine Myocardial Signal Intensity Short Breath 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Summary

BOLD-CMR was used to assess changes in myocardial oxygenation after volunteers performed controlled hyperventilation or breath holding. Signal intensity after hyperventilation decreased whereas an increase occurred after a breath hold demonstrating that controlled breathing techniques could alter myocardial oxygenation and be identified by BOLD-CMR in healthy volunteers.

Background

Systemic changes of blood gases (CO2, O2) affect haemoglobin (Hb) saturation. Blood Oxygen Level-Dependent (BOLD-) CMR can be used to monitor changes of myocardial oxygenation. We hypothesized that oxygen-sensitive CMR detects changes in myocardial tissue oxygenation induced by hyperventilation and apnea.

Methods

A group of 7 healthy volunteers were instructed to hyperventilate for 1 and 2 minutes followed by a long free breath hold. A second group of 5 aquatic athletes performed a 60s breath hold and a free maximal breath hold. BOLD-sensitive SSFP cines were acquired during breath holds as well as before and after hyperventilation. Changes in signal intensity over the procedures were expressed as % change of the baseline. Capillary blood gases were measured prior to and after the procedures.

Results

Voluntary breath holds of athletes were significantly longer (105±38s) than those of other volunteers (38±12s). Breath holds lead to a significant increase in signal intensity (*p<0.001), correlated with the length of breath hold (R=0.566, *p=0.018). Capillary pCO2 did not change during breath holds, while pO2 increased during shorter breath holds of 38s (+8.8 mmHg, *p=0.03) and decreased in long breath holds of 105s (-14.5mmHg, *p=0.03). On the other hand, hyperventilation resulted in a significant decrease of myocardial signal intensity, associated with a decrease of capillary pCO2 of 5.9 mmHg during 1 min of hyperventilation (*p<0.001) and 8.7 mmHg during a 2 min hyperventilation period (*p<0.001). Capillary pO2 was not altered by hyperventilation.

Conclusions

Our results demonstrate that BOLD-CMR can identify changes in myocardial oxygenation induced by controlled breathing maneuvers.

Funding

Husky Energy Program for the Early Detection of Cardiovascular Disease
Figure 1

The %-change in SI was significant after hyperventilation or a breath hold (*p<0.001) as the %-change in SI was significant between groups undergoing hyperventilation or a breath hold (#p<0.05).

Copyright information

© Guensch et al; licensee BioMed Central Ltd. 2012

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Authors and Affiliations

  • Dominik P Guensch
    • 1
  • Kady Fischer
    • 1
  • Jacqueline Flewitt
    • 1
  • Janelle Yu
    • 1
  • Ryan Lukic
    • 1
  • Julian A Friedrich
    • 1
  • Matthias G Friedrich
    • 1
  1. 1.Kady Fischer, Stephenson Cardiovascular MR CentreCalgaryCanada

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