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This Article Full Text Full Text (PDF) All Versions of this Article: 294/3/H1304    most recent 01186.2007v1 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 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 Sala-Mercado, J. A. Articles by O'Leary, D. S. Search for Related Content PubMed PubMed Citation Articles by Sala-Mercado, J. A. Articles by O'Leary, D. S.

Spontaneous baroreflex control of heart rate versus cardiac output: altered coupling in heart failure

Departments of ¹Physiology and ²Surgery, Wayne State University School of Medicine, Detroit, Michigan; ³Laboratory for Applied Human Physiology, Faculty of Human Development, Kobe University, Kobe, Japan; ⁴Laboratory for Human Performance Research, Osaka International University, Osaka, Japan; and ⁵Dipartimento Medicina Interna, Universita di Roma Tor Vergata, and ⁶Instituto di Ricovero e Cura a Carattere Scientifico San Raffaele Pisana, Roma, Italy

Submitted 11 October 2007 ; accepted in final form 5 January 2008

Dynamic cardiac baroreflex responses are frequently investigated by analyzing the spontaneous reciprocal changes in arterial pressure and heart rate (HR). However, whether the spontaneous baroreflex-induced changes in HR translate into changes in cardiac output (CO) is unknown. In addition, this linkage between changes in HR and changes in CO may be different in subjects with heart failure (HF). We examined these questions using conscious dogs before and after pacing-induced HF. Spontaneous baroreflex sensitivity in the control of HR and CO was evaluated as the slopes of the linear relationships between HR or CO and left ventricular systolic pressure (LVSP) during spontaneous sequences of greater or equal to three consecutive beats when HR or CO changed inversely versus pressure. Furthermore, the translation of baroreflex HR responses into CO responses (HR-CO translation) was examined by computing the overlap between HR and CO sequences. In normal resting conditions, 44.0 ± 4.4% of HR sequences overlapped with CO sequences, suggesting that only around half of the baroreflex HR responses cause CO responses. In HF, HR-LVSP, CO-LVSP, and the HR-CO translation significantly decreased compared with the normal condition (–2.29 ± 0.5 vs. –5.78 ± 0.7 beats·min^–1·mmHg^–1; –70.95 ± 11.8 vs. –229.89 ± 29.6 ml·min^–1·mmHg^–1; and 19.66 ± 4.9 vs. 44.0 ± 4.4%, respectively). We conclude that spontaneous baroreflex HR responses do not always cause changes in CO. In addition, HF significantly decreases HR-LVSP, CO-LVSP, and HR-CO translation.

arterial baroreflex sensitivity; parasympathetic activity; stroke volume