1起搏概念PPT.ppt

Epicardial or myocardial leads are implanted to the outside of the heart. These implants represent less than 5% of leads implanted, and are used primarily in pediatric cases or for patients in whom transvenous lead implant is contraindicated. Presenter Note: Explain that the system presented here is a bipolar system: the anode for a unipolar system is actually the IPG itself. Note that this topic will be covered in more detail within the next few minutes. On this slide, the anode is labeled for a a bipolar system. Pacing in the VVI/R mode and loss of AV synchrony can lead to pacemaker syndrome. Pacemaker syndrome can be defined as an assortment of symptoms related to the adverse hemodynamic impact from the loss of AV synchrony. Atrial pacemakers should only be used with patients who have proven AV conduction and regular follow-up testing available. The notation at the top refers to mode, lower rate, and upper rate parameters. This mode of operation can be described as atrial synchronous pacing or atrial tracking. Pacing in the atrium and ventricle is often described as AV sequential pacing. Insulation around the lead wire prevents current loss from the lead wire. Electrical current seeks the path of least resistance. An insulation break that exposes wire to body fluids which have low resistance causes: Lead impedance to fall Current to drain into the body Battery depletion Impedance values below 300 W. Insulation breaks are often marked by a trend of falling impedance values. An impedance reading that changes suddenly or one that is 30% is considered significant and should be watched closely. Insulation may remain intact but the wire may break within the insulating sheath. Impedance may exceed 3,000 W. Current flow may be too low to be effective. If a complete fracture of the wire occurs: No current will flow Impedance number will be 搃nfinite When suspecting a wire break, look for a trend in an increase in impedance values rather than a single lead impeda