Tuesday 14 June 2016

Failure of the Conduction System of the Heart-Commotio Cordis

Failure of the Conduction System of the Heart
The sinuatrial node is the spontaneous source of the cardiac impulse. The atrioventricular node is responsible for picking up the cardiac impulse from the atria. The atrioventricular bundle is the only route by which the cardiac impulse can spread from the atria to the ventricles. Failure of the bundle to conduct the normal impulses results in alteration in the rhythmic contraction of the ventricles (arrhythmias) or, if complete bundle block occurs, complete dissociation between the atria and ventricular rates of contraction. The common cause of defective conduction through the bundle or its branches is atherosclerosis of the coronary arteries, which results in a diminished blood supply to the conducting system

Commotio Cordis
This condition results in ventricular fibrillation and sudden death and is caused by a blunt nonpenetrating blow to the anterior chest wall over the heart. It occurs most commonly in the young and adolescents and is often sports-related. The sudden blow is frequently produced by a baseball, baseball bat, lacrosse ball, or fist or elbow. The common incidence in the young is most likely due to the compliant chest wall due to the flexible ribs and costal cartilages and the thin undeveloped chest muscles. Apparently, timing of the blow relative to the cardiac cycle is critical; ventricular fibrillation is most likely to occur if the blow occurs during the upstroke of the T wave of the electrical activity of the cardiac muscle.
  




















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