No abstract

The effectiveness and safety of a pacemaker with automatic control of capture was evaluated in 162 patients followed at 27 Spanish centers. The aim of our prospective, multicenter, and randomized trial was to determine the relationship between the voltage output of the pulse generator and the stimulation threshold. We randomized 162 patients (107 men, mean age 75 +/- 12 years). We implanted a ventricular pacemaker model Regency SR+ or SC+ with Pacesetter's low polarization bipolar leads Membrane E 1450. The patients were randomized to receive Autocapture or not; group I (81 patients) Autocapture On, pulse output automatically adjusted and group II (81 patients) Autocapture Off, fixed output parameters (3.9 V, 0.37 ms). We performed a 6-month follow-up measuring stimulation threshold by means of the VARIO test and Autocapture test, evoked response signal, and R wave signal. The mean R wave was 15.77 +/- 3.5 mV at the end of the follow-up for group I, and 14.91 +/- 6.8 mV for group II (P = NS). The measured evoked response at the end of the follow-up was 9.25 mV in Group I and 8.48 mV in Group II (P = NS). The stimulation threshold was not different between groups. The current density created with the voltage and pulse width used in this study (< or = 3.9 V and 0.37 ms) at the tip of this electrode during the maturation process had no influence on the development of the chronic detection and stimulation thresholds.

No abstract

Endocardial pacemaker electrode implantation can be difficult in patients with anomalous superior vena cava (SVC). Venography and CAT scan showed that the patient lacked SVC venous drainage and that systemic veins drained into the inferior vena cava through the azygos vein. A temporary stimulation electrode was placed by puncture of the femoral vein, permanent stimulation by venotomy of the epigastric vein, with the electrode inserted through the external iliac vein.

Magnetic resonance imaging (MRI) is currently contraindicated in cardiac pacemaker (PM) recipients. The objectives of this prospective study were to (1) reassess the risks of performing an MRI scan in patients with PM, (2) compared the pacing functions before and after the exposure to MRI, and (3) monitor the development of possible adverse effects. Thirteen patients implanted with an Affinity DR model 5330 PMs (St. Jude Medical) connected to a Tendril model 1388 leads (St. Jude Medical) underwent 2.0 T-MRI for a variety of indications. All patients displayed a stable spontaneous rhythm at the time of the MRI scan and were not considered to be PM-dependent. The sensing and pacing functions were analyzed and the impedance of both leads was measured before and after the scan. The MRI scan was performed with all PM programmed in DDD mode. The sensing configuration was bipolar. All patients were monitored utilizing a standard electrocardiographic monitor and direct verbal communication. PM Inhibition, asynchronous pacing, or inappropriately rapid pacing was not observed. No patient reported discomfort, heat, or motion sensation at the PM implant site. There were no significant differences in the sensing, stimulation, AutoCapture threshold, and lead impedance measurements before and after MRI. The results of this study suggest that performing 2.0 T-MRI scans in patients with Affinity DR model 5330 PM connected to a Tendril model 1388 lead is safe.