INTRODUCTION: Persistent systemic hypertension after surgical repair of coarctation of the aorta (CoA) is not well understood. We have shown that congenital heart disease, such as patent ductus arteriosus, and cardiovascular surgery of the right ventricular outflow tract alters the ability of nodose ganglioncardiac sensory neurites to transduce mechanical and chemical stimuli in piglet models. These cardiac afferent signals modify circulatory behaviour. Therefore, we believe persisting systemic hypertension may be the result of modifying cardiac afferent neuronal behaviour.
OBJECTIVE: We hypothesised that the development of acute CoA will alter the ability of neonatal cardiac sensory neurites to transduce the physiologic milieu of the heart as reflected in the activity of nodose ganglion cardiac afferent neurons.
METHOD: Nine 8 weeks old piglets (13 ± 0.98 kg) underwent surgery to expose the nodose ganglion in the neck and to place a ligature around the thoracic descending aorta near the aortic isthmus. Spontaneous activity from nodose ganglion cardiac afferent neurons was measured in situ and extracellular recording techniques. The ligature was tightened to produce a pressure gradient simulating an acute coarctation. Neuronal activity of cardiac sensory neurites associated with nodose ganglion afferent neurons was measured before and after creating a gradient across the aortic ligature, and then after release of the ligature.
RESULTS: See table.
CONCLUSION: Sensory cardiac neuronal activity tends to fall (p=0.21) during acute CoA with a 78 mmHg gradient without a significant change in heart rate or diastolic descending aortic pressure. Neuronal activity remains depressed after removal of the CoA.