Ariya Lauretti Noti Pdf
Abstract In children with structurally normal hearts, the mechanisms of arrhythmias are usually the same as in the adult patient. Some arrhythmias are particularly associated with young age and very rarely seen in adult patients. Arrhythmias in structural heart disease may be associated either with the underlying abnormality or result from surgical intervention. Chronic haemodynamic stress of congenital heart disease (CHD) might create an electrophysiological and anatomic substrate highly favourable for re-entrant arrhythmias. As a general rule, prescription of antiarrhythmic drugs requires a clear diagnosis with electrocardiographic documentation of a given arrhythmia. Risk–benefit analysis of drug therapy should be considered when facing an arrhythmia in a child. Prophylactic antiarrhythmic drug therapy is given only to protect the child from recurrent supraventricular tachycardia during this time span until the disease will eventually cease spontaneously. In the last decades, radiofrequency catheter ablation is progressively used as curative therapy for tachyarrhythmias in children and patients with or without CHD.
Even in young children, procedures can be performed with high success rates and low complication rates as shown by several retrospective and prospective paediatric multi-centre studies. Three-dimensional mapping and non-fluoroscopic navigation techniques and enhanced catheter technology have further improved safety and efficacy even in CHD patients with complex arrhythmias. During last decades, cardiac devices (pacemakers and implantable cardiac defibrillator) have developed rapidly. Free illustrator hair brushes for photoshop. The pacing generator size has diminished and the pacing leads have become progressively thinner. These developments have made application of cardiac pacing in children easier although no dedicated paediatric pacing systems exist. ,, Anatomy of the conduction system of the heart Conduction system in normally structured hearts The sinus node is usually located immediately subepicardially in the terminal groove (sulcus terminalis) on the lateral margin of the junction between the superior caval vein and the right atrium ( Figure A). It is spindle-shaped, with a tapering tail in the majority of hearts.
In about one-tenth of individuals, it is shaped like a horseshoe and straddles the crest of the right atrial appendage. At the borders, the nodal cells are adjacent to working myocytes in places and short tongues of transitional cells inter-digitate with ordinary musculature in others. The tail of the sinus node penetrates postero-inferiorly into the musculature of the terminal crest to varying distances. Apart from the occasionally long tail, and the tongues of transitional cells, no histologically specialized pathways are seen in the internodal musculature. ( A) Diagram of the cardiac conduction system.