Tedisamil - Molecular Problem

Molecular Problem

Arrhythmias are broadly defined as abnormal electrical activity in the heart and can affect both the atria and ventricles. Atrial arrhythmias are the most common type of arrhythmia with several subtypes currently described, including atrial fibrillation. In atrial fibrillation, there is continual quivering of the atria as contraction of the muscle is uncoordinated. Under normal conditions, an electrical impulse from the sinoatrial (SA) node is distributed rapidly throughout the atria causing coordinated excitement and inactivation of atrial muscle cell ion channels resulting in uniform contraction and relaxation of the muscle fibres. During fibrillation, other electrical signals overwhelm the SA node and ion channel excitement is no longer uniform throughout the atria. This results in inappropriate activation properties, further preventing uniform contraction and relaxation of the muscle. Subsequent action potentials from the SA node will not be able to uniformly excite the muscle as not all of the channels will be available to open as some will still be held in the inactivation phase. This results in disjointed contraction, or quivering, seen in the atrial muscle during fibrillation.