Intraindividual comparison of diltiazem and verapamil on induction of paroxysmal supraventricular tachycardia

Temporary atrial electrode for the treatment of supraventricular tachycardia after cardiac operations

BACKGROUND

Supraventricular tachycardia is a common postoperative complication early after cardiac operations. A temporary atrial patch electrode for low-energy atrial defibrillation was developed in 1992 and subsequently tested.

METHODS

The electrode first was tested and removed intraoperatively during open heart operations in 10 patients (phase I). After the intraoperative testing, the temporary atrial patch electrode was implanted in 20 patients for postoperative termination of spontaneous episodes of supraventricular tachycardia (phase II). When supraventricular tachycardia occurred, biphasic shocks (1.2 to 5 J) were applied and the atrial defibrillation thresholds were measured.

RESULTS

In phase I, the mean intraoperative atrial defibrillation threshold was 1.6 +/- 1.4 J, with a mean shock impedance of 64 +/- 7.3 omega. In phase II, 6 of 20 patients (30%) had 7 episodes of atrial fibrillation (n = 6) and atrial flutter (n = 1) after operation. In 5 patients, the supraventricular tachycardia could be converted to a sinus (n = 5) or normofrequent atrioventricular rhythm (n = 1). The mean postoperative defibrillation threshold was 2.7 +/- 2.1 J, with a mean shock impedance of 50.2 +/- 6.8 omega.

CONCLUSIONS

The temporary atrial patch electrode allows low-energy defibrillation of episodes of atrial fibrillation. It may serve as an alternative therapeutic option for the treatment of supraventricular tachycardia.

Effects of extracellular calcium concentrations and calcium antagonists on vitellogenin induction by estradiol-17 beta in primary hepatocyte culture in the rainbow trout Oncorhynchus mykiss

The involvement of calcium in vitellogenin (Vg) synthesis in response to estradiol-17 beta (E2, 2 x 10(-6) M) was electrophoretically examined in primary hepatocyte culture in the rainbow trout Oncorhynchus mykiss. The relative rate of Vg synthesis was evaluated by measuring the integrated optical density of the Vg band after SDS-PAGE and expressed as a percentage of Vg to total proteins. The induction of Vg by E2 did not occur at 0 meq Ca/liter, while some proteins other than Vg (main subunit) were weakly synthesized. Vg synthesis increased in a calcium concentration-dependent way and reached the maximum at 5 meq Ca/liter in the incubation medium. The addition of bovine growth hormone (50 ng/ml) and/or ovine prolactin (100 ng/ml) had no effect on stimulating Vg synthesis by E2, regardless of the calcium concentrations in the medium. Lanthanum and verapamil (10(-4) M) markedly inhibited Vg synthesis, while diltiazem (10(-4) M) was insignificant. Reactive blue (10(-4) was also effective in inhibiting Vg synthesis to about 60% of the control. These results suggest that the synthesis of Vg, a calcium-binding protein, is more susceptible to calcium than are other proteins. Receptor-operated and verapamil-sensitive calcium channels have been proposed to be involved in calcium entry into hepatocytes in rainbow trout.