Carotid body ablation effective for congestive heart failure in rats

Image: PD 

1. In an animal model of congestive heart failure (CHF), carotid body albation was associated with reduced sympathetic activation, apneic episodes, cardiac remodeling, and mortality. 

2. Appetite and activity level were unaffected by carotid body denervation. 

Evidence Rating Level: 1 (Excellent) 

Study Rundown: CHF is in part mediated by deranged neurohormonal excitation, affecting the respiratory response to hypoxia and other stresses. Given that the carotid body is a key neurohormonal regulator that has been shown to become overactive from chronic low blood flow in CHF, it has been theorized as a potential target to interrupt excess afferent sympathetic triggers.

This animal model of CHF demonstrated a significant divergence in disease progression between ablated rats and those whose carotid bodies were intact. The rats showed consistent improvements across multiple physiologic domains of sympathetic excitation, with less respiratory and heart rate variability, as well as fewer catecholaminergic neurons in the brainstems of ablated rats. This resulted in decreased cardiac dilation and tissue remodeling, and lower mortality after 14 weeks. While this study demonstrates a mortality benefit in the controlled experimental environment, it is unknown whether the blunted sympathetic response would have adverse effects in the more varied environment humans with CHF would experience (e.g. altitude changes, co-occurring respiratory disease, etc.).

Click to read the study in the Journal of the American College of Cardiology

Click to read the accompanying editorial in the Journal of the American College of Cardiology

In-Depth [randomized controlled animal trial]: CHF was induced in 71 rats by coronary artery ligation. They underwent carotid body cryoablation at either two weeks or sixteen weeks. Ejection fraction, cardiac tissue remodeling, respiratory function, and arrhythmias were assessed. Ejection fraction deteriorated equally in both groups for the first two weeks but diverged after carotid body denervation (p<0.05). Significant changes in respiratory patterns involved the variability of breathing: there was dampening of the CHF hyperactive response to hypoxia among rats with carotid body denervation (p<0.01). At 14 weeks, mortality was 85% versus 45% in the denervated group (p=0.04).

By Gina Siddiqui and Allen Ho

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