Introduction:
Carotid body denervation (CBD) abolishes the carotid body hypersensitivity induced sympathoexcitatory hypertension. Since the carotid body hypersensitivity is a salient feature and predicts poor outcome of chronic heart failure (CHF), we hypothesized that CBD restores normal autonomic balance, thus improves CHF in rats after large myocardial infarction (MI).
Methods:
We created MI in 8 weeks Sprague-Dawley rats. Surviving rats at 2 weeks after MI were randomized into CBD (n=11) and sham-operated (Sham; n=13) groups. We removed the tissues around the carotid bifurcation and established CBD. In some rats (Sham; n=5, CBD; n=5), we telemetrically recorded heart rate (HR). One month after CBD, we compared physiological, histological and immunochemical findings between CBD and Sham.
Results:
CBD significantly reduced HR (337±15 vs. 364±12 bpm, p<0.05). CBD markedly increased the power spectral density of HR in the high frequency range (81.0±9.5 vs. 29.0±8.2 n.u., p<0.05) and decreased that of the low frequency/high frequency ratio (0.6±0.2 vs. 1.8±0.5, p<0.05) indicating the restoration of autonomic balance. CBD significantly reduced biventricular weight (3.1±0.3 vs. 3.7±0.3 g/kg, p<0.05) and left ventricle (LV) end-diastolic pressure (22±5 vs. 33±5 mmHg, p<0.01) and increased maximum LV dp/dt (5118±809 vs. 4217±472 mmHg/sec, p<0.05). CBD reduced lung weight (a marker of pulmonary edema) (6.8±2.0 vs. 12.4±1.5 g/kg, p<001). Furthermore, CBD reduced plasma brain natriuretic peptide (70±43 vs. 166±71 pg/ml, p<0.01) and plasma norepinephrine as an index of sympathetic drive (384±202 vs. 1048±997 pg/ml, p<0.05). CBD significantly reduced the number of inflammatory macrophages (345±45 vs. 474±73 counts/mm2, p<0.05) in the LV and the plasma concentration of interleukin-1β (14.3±4.7 vs. 24.5±11.8 pg/ml, p<0.05) indicating that CBD also suppressed the inflammatory response in CHF.
Conclusions:
CBD restores normal autonomic balance and prevents the worsening of heart failure in rats after large myocardial infarction. CBD may serve as a novel neuro-modulatory therapy for CHF patients.
Carotid body denervation prevents pulmonary edema, attenuates left ventricular remodeling and restores normal autonomic balance in chronic heart failure after myocardial infarction (709.5)
