The new detection algorithm incorporated in the Ventak AV did not inadvertently withhold therapy for ventricular tachyarrhythmias, but at the same time the number of inappropriate therapies for atrial fibrillation was not decreased in comparison to a single chamber device.

Even with the use of biphasic shocks, up to 5% of patients need an additional subcutaneous lead to obtain a defibrillation safety margin of at least 10 J. The number of patients requiring additional subcutaneous leads may even increase, because recent generation devices have a < 34 J maximum output in order to decrease their size. In 20 consecutive patients, a single element subcutaneous array lead was implanted in addition to a transvenous lead system consisting of a right ventricular (RV) and a vena cava superior lead using a single infraclavicular incision. The RV lead acted as the cathode; the subcutaneous lead and the lead in the subclavian vein acted as the anode. The biphasic defibrillation threshold was determined using a binary search protocol. Patients were randomized as to whether to start them with the transvenous lead configuration or the combination of the transvenous lead and the subcutaneous lead. In addition, a simplified assessment of the defibrillation field was performed by determining the interelectrode area for the transvenous lead only and the transvenous lead in combination with the subcutaneous lead from a biplane chest X ray. The intraoperative defibrillation threshold was reconfirmed after 1 week, after 3 months, and after 12 months. The mean defibrillation threshold with the additional subcutaneous lead was significantly (P = 0.0001) lower (5.7 +/- 2.9 J) than for the transvenous lead system (9.5 +/- 4.6 J). With the subcutaneous lead, the impedance of the high voltage circuit decreased from 48.9 +/- 7.4 omega to 39.2 +/- 5.0 omega. In the frontal plane, the interelectrode area increased by 11.3% +/- 5.5% (P < 0.0001) and in the lateral plane by 29.5% +/- 12.4% (P < 0.0001). The defibrillation threshold did not increase during follow-up. Complications with the subcutaneous electrode were not observed during a follow-up of 15.8 +/- 2 months. The single finger array lead is useful in order to lower the defibrillation threshold and can be used in order to lower the defibrillation threshold.

ICDs provide protection against sudden cardiac death in patients with life-threatening ventricular arrhythmias. Nevertheless, most ICD recipients receive adjunctive antiarrhythmic drug therapy to reduce the number of recurrent episodes and ICD discharges. The aim of the study was to compare the efficacy of metoprolol and d,l-sotalol in preventing VT/VF recurrences in patients with an ICD in a prospective, randomized trial. One hundred patients (83 men, 17 women; mean age 59 years, SD +/- 11 years) were randomized to receive metoprolol or sotalol after implantation of an ICD. There were no significant differences between the two groups with regard to age, sex, underlying cardiac disease, left ventricular ejection fraction, NYHA class assessment and clinical arrhythmia. The median follow-up was 728 days (25th percentile: 530 days, 75th percentile: 943 days) in the metoprolol group and 727 days (25th percentile: 472 days, 75th percentile: 1,223 days) in the sotalol group (P = 0.52). Thirty-three patients treated with metoprolol and 30 patients receiving sotalol had at least one episode during the follow-up. Event-free survival curves were generated for the two treatment arms using the Kaplan-Meier method and showed no significant difference (P = 0.68). Eight patients treated with metoprolol and six patients treated with sotalol died during follow-up. Total mortality was not significantly different between the two study groups (P = 0.43). Metoprolol is as efficacious as sotalol in preventing VT/VF recurrences in patients with an ICD.

Scimitar syndrome has a variable presentation depending on the age at which the diagnosis is made. We report a case of a young woman (age 18 years) with suspected right pulmonary hypoplasia in whom a scimitar syndrome was diagnosed. Using MRI morphological findings and hemodynamic significance of the syndrome were assessed. Left-to-right shunt was calculated from blood flow measurements performed in the ascending aorta, the main pulmonary artery, and the aberrant scimitar vein.

The lack of specificity in the detection of ventricular tachyarrhythmias remains a major clinical problem in the therapy with ICDs. The stability criterion has been shown to be useful in discriminating ventricular tachyarrhythmias characterized by a small variation in cycle lengths from AF with rapid ventricular response presenting a higher degree of variability of RR intervals. But RR variability decreases with increasing heart rate during AF. Therefore, the aim of the study was to determine if the sensitivity and specificity of the STABILITY algorithm for spontaneous tachyarrhythmias is related to ventricular rate. Forty-two patients who had received an ICD (CPI Ventak Mini I, II, III or Ventak AV) were enrolled in the study. Two hundred ninety-eight episodes of AF with rapid ventricular response and 817 episodes of ventricular tachyarrhythmias were analyzed. Sensitivity and specificity in the detection of ventricular tachyarrhythmias were calculated at different heart rates. When a stability value of 30 ms was programmed the result was a sensitivity of 82.7% and a specificity of 91.4% in the detection of slow ventricular tachyarrhythmias (heart rate < 150 beats/min). When faster ventricular tachyarrhythmias with rates between 150 and 169 beats/min (170-189 beats/min) were analyzed, a stability value of 30 ms provided a sensitivity of 94.5% (94.7%) and a specificity of 76.5% (54.0%). For arrhythmia episodes > or = 190 beats/min, the same stability value resulted in a sensitivity of 78.2% and a specificity of 41.0%. Even when other stability values were taken into consideration, no acceptable sensitivity/specificity values could be obtained in this subgroup. RR variability decreases with increasing heart rate during AF while RR variability remains almost constant at different cycle lengths during ventricular tachyarrhythmias. Thus, acceptable performance of the STABILITY algorithm appears to be limited to ventricular rate zones < 170 beats/min.