Use of the Saline Infusion Electrode Catheter for Improved Energy Delivery and Increased Lesion Size in Radiofrequency Catheter Ablation

Although radiofrequency catheter ablation has undergone explosive growth as the treatment for a variety of arrhythmias, a limiting factor with the existing catheter delivery system has been the relatively small size of the lesions, which appears to be in part due to coagulum formation around the catheter tip, producing a rise in impedance and limiting energy delivery. In order to test the hypothesis that infusion of saline during radiofrequency current application can increase the lesion size and decrease the incidence of impedance rise, ten dogs were each given two radiofrequency ablation lesions to the left ventricular endocardium. One of these lesions was delivered with a standard 7 French quadripolar catheter with a 2-mm tip, and the second was done with a 7 French Iuminal electrode catheter (also with a 2-mm tip) for the infusion of normal saline during the delivery of radiofrequency energy. Energy was delivered for 60 seconds at either 10 or 20 watts at two distinct sites in the left ventricle for each animal. Four to 7 days following ablation, the animals were sacrificed for pathological examination. The lesions created with the saline infusion catheter were significantly bigger than those produced with a standard catheter (7.3 × 7.0 × 5.1 vs 5.2 × 4.9 × 3.5 mm, respectively, P < 0.001). At the lower energy level (10 W), none of the animals with the saline infusion catheter experienced an impedance rise versus 3 of 5 of the animals in whom the standard catheter was used. At the higher level (20 W), only 1 of 5 dogs had an impedance rise with the saline infusion catheter versus 5 of 5 with the standard catheter. We conclude that the use of a saline infusion catheter for radiofrequency energy delivery during catheter ablation produces a significantly larger lesion than that produced with a standard catheter and is effective in preventing impedance rise.     

Oral etoposide in the treatment of cutaneous large-cell lymphomas. A preliminary report of four cases

The favourable results of oral etoposide as single-agent therapy in four patients with a cutaneous lymphoma other than mycosis fungoides are reported. In all cases other chemotherapeutic options were limited because of prior chemotherapy or the age of the patients. Therapy with etoposide resulted in an initial complete remission in all patients, and was associated with minimal side-effects.     

Left Ventricular Free-Wall Rupture Occurring During Programmed Ventricular Stimulation in a Patient With Recent Myocardial Infarction

In this report we describe a patient who died during programmed ventricular stimulation due to a rupture of the left ventricular free wall at the site of a recent myocardial infarction. The patient was a 75-year-old male who presented with an extensive anterior wall myocardial infarction complicated by sustained ventricular tachycardia occurring 8 days after admission. Cardiac catheterization revealed total occlusion of left anterior descending coronary artery and an anteroapical aneurysm. The patient died due to electromechanical dissociation during electrophysiological testing 11 days after myocardial infarction. Postmortem examination showed a rupture of the left ventricular free wall at the site of the myocardial infarction and distant from the site of catheter placement. It is suggested that caution be taken in choosing patients for electrophysiological studies who have had recent large myocardial infarctions with ventricular aneurysm.     

Permanent Left Atrial Pacing with a Specifically Designed Coronary Sinus Lead

This article reports the original use of a specifically designed coronary sinus (CS) lead for permanent left atrial (LA) pacing. The device is characterized by its distal end shape featuring a double 45° angulation. which ensures very close contact with the CS upper wall. The device was successfully implanted in 39 out of 40 patients (97.5%). The tip electrode was eventually positioned in the distal CS in 9 patients, in the middle CS in 21 patients, and close to the ostium in the proximal CS in 9 patients. The mean acute pacing threshold voltage was 0.9 ± 0.5 V with a mean impedance of 578 ± 144 Ω as measured in unipolar distal configuration at 0.5 ms pulse width (PW). The mean A wave amplitude was 3.5 ± 2.1 mV. Early lead dislodgment occurred only once (3%) when the tip electrode was placed in the distal or middle CS, but more often (4/9 cases) when it was placed in the proximal CS. After a mean follow-up duration of 14 ± 8.5 months, 35 of the 39 successfully implanted leads (89.7%) were still functional in terms of LA pacing and sensing. The mean chronic pacing threshold voltage was 1.5 ± 0.8 V and the mean A wave amplitude was 2.7 ± 1.6 mV. There were no lead related complications. In conclusion, the device proved to be safe and highly effective for permanent LA pacing, provided the distal tip could be positioned in the distal or middle part of the CS.