The American journal of cardiology
-
Lorcainide is a new type 1 antiarrhythmic drug that is well absorbed orally, with bioavailability increasing with both dose and continued administration. It is metabolized through the liver, and patients with significant liver disease will require dosage reduction. ⋯ The levels of this metabolite are nearly twice those of lorcainide at steady state. The long half-life of the metabolite and the changing bioavailability of lorcainide require that a given dose be administered for 1 week for the maximum effect to be demonstrated.
-
Dual-chamber cardiac pacing (DDD) offers obvious theoretical advantages over traditional ventricular demand (VVI) pacing. Nevertheless, no widely agreed upon criteria exist for the selection of patients for physiologic DDD pacemakers compared with the simpler VVI systems. Accordingly, a non-invasive method for measuring cardiac output (Doppler ultrasound) was used to identify candidates for pacing who would derive the greatest hemodynamic benefit from DDD vs VVI pacing. ⋯ In these patients, the mean improvement in cardiac output was 30.4 +/- 8.6% with DDD vs VVI pacing, as opposed to an average increase of only 14.4 +/- 3.4% in the remaining 20 patients (p = 0.02). Thus, Doppler ultrasound can be used to quantitate the change in cardiac output at rest that occurs with DDD vs VVI pacing. The change is independent of the level of left ventricular function but is substantially higher when there is evidence of ventriculoatrial conduction or the pacemaker syndrome.