Neurohumoral activation and progression of heart failure: hypothetical and clinical considerations

The paraventricular nucleus of the hypothalamus - a potential target for integrative treatment of autonomic dysfunction

BACKGROUND

The paraventricular nucleus of the hypothalamus (PVN) has emerged as one of the most important autonomic control centers in the brain, with neurons playing essential roles in controlling stress, metabolism, growth, reproduction, immune and other more traditional autonomic functions (gastrointestinal, renal and cardiovascular).

OBJECTIVES

Traditionally the PVN was viewed as a nucleus in which afferent inputs from other regions were faithfully translated into changes in single specific outputs, whether neuroendocrine or autonomic. Here we present data which suggest that the PVN plays significant and essential roles in integrating multiple sources of afferent input and sculpting an integrated autonomic output by concurrently modifying the excitability of multiple output pathways. In addition, we highlight recent work that suggests that dysfunction of such intranuclear integrative circuitry contributes to the pathology of conditions such as hypertension and congestive heart failure.

CONCLUSIONS

This review highlights data showing that individual afferent inputs (subfornical organ), signaling molecules (orexins, adiponectin), and interneurons (glutamate/GABA), all have the potential to influence (and thus coordinate) multiple PVN output pathways. We also highlight recent studies showing that modifications in this integrated circuitry may play significant roles in the pathology of diseases such as congestive heart failure and hypertension.

Design and features of the Acorn CorCap Cardiac Support Device: the concept of passive mechanical diastolic support

The Laplace equation points to the importance of ventricular wall stress as a factor in heart failure development and progression. Based on animal and clinical experience with active and passive cardiomyoplasty, a synthetic passive constraint was proposed as a means of reducing excessive wall stress, and thus assuaging disease progression. The Acorn CorCap CSD Cardiac Support Device was designed to provide passive diastolic support and serve as a constraint against chronic cardiac dilation in heart failure. Basic and uncomplicated in appearance, the device nevertheless incorporates numerous sophisticated structural and functional features intended maximize therapeutic value. The device is fabricated from medical grade multifilament polyester yarn, in a specific knit construction chosen to provide structural integrity, low physical profile, pliability for intimate contact with the epicardial surface, ease of manipulation during implantation, and anisotropic compliance characteristics to encourage beneficial reverse remodeling.