CORRESPONDENCE: LETTER TO THE EDITOR
Reply
Alberto U. Ferrari, MD*,
Giuseppe Mancia, MD and
Alberto Radaelli, MD
* Divisione di Riabilitazione Cardiologica, Centro Interuniversitario di Fisiologia Clinica e Ipertensione, Via Pergolesi, 33, 20052 Monza (MI), Italy (Email: a.ferrari{at}hsgerardo.org).
We appreciate the comments by Drs. Monahan and Ray concerning our suggestion that, in heart failure patients, polyunsaturated fatty acid (PUFA) supplementation may attenuate efferent sympathetic nerve overactivity (SNA) (1). We entirely agree that this issue is of potential clinical relevance and merits direct experimental testing, as indicated in the discussion of our own study and reinforced by Floras and Bagai in their accompanying editorial (2).
This question is made even more interesting because, as appropriately recalled by our colleagues, they previously observed (3) that PUFA supplementation failed to modify resting muscle SNA in healthy individuals. Conversely, we all perfectly realize that the two possibilities (no change in the healthy subject, reduction in the heart failure patient) are by no means mutually exclusive considering that regulation of autonomic ouflows is significantly altered in cardiac systolic dysfunction, and may thus be differentially affected by PUFA supplementation compared to the normal condition.
While awaiting more direct evidence (cardiac norepinephrine spillover? peroneal microneurography? metaiodobenzylguanidine cardiac scans?), all we can do is to contemplate the most reasonable interpretation of the indirect evidence emerging from our study, namely that PUFA 1) increased both low- and high-frequency powers of the RR interval; 2) potentiated cardiovascular inhibitory control by the baroreflex; 3) fell short of significantly slowing heart rate; and 4) markedly enhanced overall RR interval variability. Each of the previously-cited effects points to a PUFA-related reduction in sympathetic (and probably an enhanced vagal) nerve activity.
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References
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- Radaelli A, Cazzaniga M, Viola A, et al. Enhanced baroreceptor control of the cardiovascular system by polyunsaturated fatty acids in heart failure patients J Am Coll Cardiol 2006;48:1600-1606.[Abstract/Free Full Text]
- Floras J, Bagai A. Polyunsaturated fatty acids and the post-infarct patient: a recipe for baroreflex health? J Am Coll Cardiol 2006;48:1607-1609.[Free Full Text]
- Monahan KD, Wilson TE, Ray CA. Omega-3 fatty acid supplementation augments sympathetic nerve activity responses to physiological stressors in humans Hypertension 2004;44:732-738.[Abstract/Free Full Text]
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