Defibrillators: Cardiac Neural Innervation and Vagal Stimulation

BREAKING NEWS: 10.15.07--Medtronic, Inc., the world's largest maker of electronic heart devices, announced they are suspending sales of Sprint Fidelis leads. According to the FDA, these wires, used to connect defibrillators to the heart, may break or erode and may increase chance of injury. Learn more about the Medtronic Sprint Fidelis Recall.

The atrioventricular (AV) node and the Bundle of His together share a rich and densely innervated supply of cholinergic and adrenergic nerve fibres. The density of innervation exceeds of what is seen in the ventricular myocardium.

Ganglia, nerve fibres and nerve nets lie close to the AV node. In the canine heart, parasympathetic nerves to the AV node region, enter at the junction of the Inferior Vena Cava on the inferior border of the left atrium adjacent to the coronary sinus.

Nerves in contact with the AV nodal fibres have been noted along with agranular and granular vesicular processes, presumably representing cholinergic and adrenergic processes.

Acetylcholine release may be concentrated around the N region of the AV node [Zipes DP 1994] It is found that the autonomic neural input demonstrates some sidedness. The right sympathetic and vagal nerves affect the sinus node more than the AV node and vice-versa.

Despite much overlap in the innervation, specific branches of the sympathetic and Vagal nerves can be seen to innervate specific parts of the conducting system [Braunwald E 1998]. The vagus modulates the cardiac sympathetic activity at prejunctional and postjunctional sites by two methods. The first involves regulating the amount of noradrenaline released and the second by inhibiting cyclic AMP-induced phosphorylation of cardiac proteins such as phospholamban.

If your or a loved has had an implantable cardioverter-defibrillator such as the recalled Guidant:

1. CONTAK RENEWAL 2, Model H155

2. CONTAK RENEWAL, Model H135, or

3. PRIZM 2 DR, Model 1861

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see also:

History History of Ventricular Fibrillation: Guidant Lawsuit Information, FREE
History ventricular fibrillation: Guidant and FREE lawsuit evaluation

Ventricular Fibrillation Dangers of Guidant CONTAK RENEWAL: Ventricular Fibrillation
Recalled Guidant CONTAK RENEWAL and Ventricular Fibrillation

Learn More Dangerous Recalled PRIZM 2 DR, Model 1861
Legal help for men and women with the dangerous PRIZM defibrillator