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Tissue Doppler indices of cardiac contractile function during whole‐body heat stress
Author(s) -
Brothers R Matthew,
Bhella Paul S.,
Shibata Shigeki,
Wingo Jonathan E.,
Levine Benjamin D.,
Crandall Craig G.
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.970.24
Subject(s) - ventricle , supine position , medicine , cardiology , ejection fraction , heat stress , cardiac function curve , heart failure , zoology , biology
Previously we demonstrated that heat stress increases ejection fraction, suggestive of improved contractile function. However ejection fraction is highly load dependent and may be an imprecise measure of contractile function. Therefore, we sought to use tissue Doppler mitral annular systolic velocity as a myocardial specific and less load dependent index to test the hypothesis that heat stress improves contractile function when compared to normothermic conditions. Peak systolic septal and lateral mitral annular systolic velocities were measured during normothermic and heat stress (i.e., Δ internal temperature 1.0 ± 0.05°C) conditions in six healthy male volunteers. Normothermic measurements were performed following a 45‐minute supine rest period and always preceded the heat stress measurements. Heat stress significantly increased septal mitral annular systolic velocity (normothermia: 8.8 ± 0.4 cm/s; heat stress: 11.1 ± 0.8 cm/s; P=0.01) and lateral mitral annular systolic velocity (normothermia: 10.4 ± 0.9 cm/s; heat stress: 13.9 ± 1.5 cm/s; P=0.03) relative to normothermic conditions. These data support our previous findings suggesting that the contractile state of the left ventricle is improved during heat stress conditions. Supported by NIH Grant NIH‐HL61388 & HL84072