Noninvasive assessment of the cardiac baroreflex
Response to downward tilting and comparison with the phenylephrine method
Naohiko Takahashi, MD*,
Mikiko Nakagawa, MD ,
Tetsunori Saikawa, MD*,
Tatsuhiko Ooie, MD* ,
Tadafumi Akimitsu, MD*,
Koji Kaneda, MD*,
Masahide Hara, MD*,
Tetsu Iwao, MD,
Hidetoshi Yonemochi, MD,
Morio Ito, MD and
Toshiie Sakata, MD*
* Department of Internal Medicine I, School of Medicine, Oita Medical University, Oita, Japan
Department of Laboratory Medicine, School of Medicine, Oita Medical University, Oita, Japan
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Figure 1 The relation between the changes in systolic blood pressure increase and corresponding RR interval lengthening observed in a 33-year old man during downward tilting. (A) Top and middle panels: electrocardiographic tracing of V5 lead and computed RR intervals. Bottom panel: arterial blood pressure (BP) recorded with tonometry. Arrows indicate the beginning and the end of downward tilting. (B) Plotting of corresponding RR interval against systolic blood pressure in this subject revealed a strong correlation (r = 0.95; p < 0.0001), yielding a baroreflex sensitivity value of 14.0 ms/mm Hg. ECG = electrocardiogram.
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Figure 2 The correlation between baroreflex sensitivity measured by the downward tilting method (DT-BRS) and that by the phenylephrine method (Phe-BRS) in 16 subjects studied; DT-BRS correlated significantly with Phe-BRS (r = 0.79; p = 0.0003).
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