tailieunhanh - Cardiac resynchronization therapy

As mentioned in Chapter 1, one relatively new approach in cardiac pacing is biventricular pacing or cardiac resynchronization. This is pacing of patients with congestive heart failure to maintain synchrony between the interventricular septum of the left ventricle and the lateral wall of the left ventricle, thus improving cardiac output, and improving the patient s symptoms and possibly patient longevity (Fig. 7-1). | In the case of atrial fibrillation, the atrial lead is not implanted. The new, and more complex, portion of the implantation is to place a lead through the coronary sinus and down a vein on the posterolateral side of the heart. This can be a technically challenging portion of pacemaker implantation, as discussed in Chapter 10. Figure 7-2 demonstrates an example of one type of posterolateral lead. It is an “inactive†lead with no tines or the ability to be secured with screw-in leads. The curve at the end is built into the lead itself (it is not there for aesthetic purposes). There are different types of curves available, but the general principle is that the curve is designed to cause pressure of the pacemaker tip against the myocardium within the narrow vein. The lateral threshold may be slightly higher than a typical threshold, but the difference is fairly minimal. The sensing is done through the right ventricular lead (the posterolateral lead paces but does not generally sense).