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Abnormal Neurovascular Control During Exercise After Myocardial Infarction
Author(s) -
Rondon Maria Urbana P. B.,
Martinez Daniel G.,
Nicolau Jose C,
Lage Rony L,
Laterza Mateus C.,
Trombetta Ivani C.,
Matos Luciana D.N.J.,
Negrao Carlos E.
Publication year - 2009
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.23.1_supplement.787.7
Subject(s) - microneurography , medicine , cardiology , blood pressure , forearm , myocardial infarction , plethysmograph , hemodynamics , blood flow , brachial artery , neurovascular bundle , heart rate , surgery , baroreflex
Objective We hypothesized that muscle sympathetic nerve activity (MSNA) responses during exercise would be exacerbated whereas forearm blood flow responses would be reduced in patients post myocardial infarction (MI). Methods We studied 23 patients (52±2 yr; ejection fraction= 56±1%), 30‐days after MI and 8 age‐matched healthy controls (C, 46±1 yr), during handgrip exercise. MSNA was measured by microneurography, forearm blood flow by venous occlusion plethysmography, and blood pressure by oscillometric method. Results Baseline MSNA was higher (57±4 vs. 35±2 bursts/100HB, P=.006), and forearm vascular conductance (FVC) was lower (1.62±0.1 vs. 2.97±0.4 units, P<.002) in MI patients when compared with C. No significant difference in mean blood pressure between groups was found (90±5 vs. 86±2 mmHg, P=.61). MSNA bursts/100HB similarly increased during peak exercise in both groups (P<.001). However, the MSNA levels were significantly higher in MI patients than in C (66±4 vs. 47±3 bursts/100HB, P=.01). FVC significantly increased during exercise in C (2.60±0.3 vs. 4.13±0.6 units, P<.001), but not in MI patients in whom FVC was unchanged (1.48±0.1 vs. 1.53±0.2 units, P=.99). Conclusion Sympathetic outflow is augmented and FVC is blunted during exercise in patients with MI. These findings highlight the abnormal neurovascular control during physiological maneuvers in patients with recent MI.