Results of a comparative study of low energy direct current with radiofrequency ablation in patients with the Wolff-Parkinson-White syndrome.

OBJECTIVE: To compare two new power sources for catheter ablation in patients with the Wolff-Parkinson-White syndrome. DESIGN: 120 consecutive patients with accessory pathways had catheter ablation. Low energy direct current (DC) was used in the first 60 patients and radio-frequency current in the next 60 patients. SETTING: Electrophysiological laboratory of a large heart institute. PATIENTS: 72 men and 48 women (mean (SD) age 35 (14) years (range 9-75)). The accessory pathways were in the left free wall in 73 patients. They were posteroseptal in 35 patients, in the right free wall in five, and anteroseptal in seven. There was no significant difference in the clinical or electrophysiological variables between the two ablation groups. RESULTS: Catheter ablation with low energy direct current was successful in 55/60 patients (92%) and radiofrequency energy was successful in 52/60 patients (87%). Low energy direct current was also successful in four of the eight patients in whom radiofrequency ablation had failed. Radiofrequency ablation was successful in two of the five patients in whom low energy direct current ablation had failed. The mean (SD) procedure and fluoroscopy times for successful ablation were 3.2 (1.5) h and 61 (40) min respectively. These times were similar for both power sources. Accessory pathway conduction recurred in 17 patients (28%) who had low energy direct current and four patients (7%) who received radiofrequency energy (p < 0.004). All patients with recurrence of an accessory pathway had successful re-ablation. CONCLUSIONS: Both new power sources successfully ablated accessory pathways, (overall success rate 94% (113/120 patients)). Radiofrequency ablation, however, did not require general anaesthesia and was associated with a significantly lower rate of recurrence of accessory pathway conduction. Therefore radiofrequency should be used initially for ablation. Low energy direct current may be most useful as a back-up in patients in whom radiofrequency ablation fails.

Success, safety, and late electrophysiological outcome of low-energy direct-current ablation in patients with the Wolff-Parkinson-White syndrome.

BACKGROUND: Percutaneous ablation of accessory pathways with the use of a defibrillator can be accomplished with high-energy direct-current (DC) shocks of 150-400 J, but complications include cardiac tamponade and sudden cardiac death, mostly resulting from significant electrical arcing and barotrauma. A new low-energy DC power source with a brief time-constant capacitive discharge delivers shocks of 2-40 J and eliminates or greatly reduces arcing. This report describes our initial experience with this device in 60 consecutive patients (mean age, 34 years; range, 9-67 years) with Wolff-Parkinson-White syndrome. Accessory pathways were located in the left free wall in 36 patients, in the right free wall in two, were posteroseptal in 18, and anteroseptal in four. Most patients (77%) had their initial diagnostic electrophysiological study and catheter ablation during the same session. METHODS AND RESULTS: Selective ablation of accessory pathways was successful in 55 patients (92%). The mean cumulative energy was 312 +/- 284 J and the mean creatine kinase MB peak (normal, 0-30 units) was 42 +/- 27 units. Patients with left free wall accessory pathways required less procedure time for ablation (2.7 +/- 0.8 versus 3.6 +/- 1.5 hours, p less than 0.0007) and less fluoroscopy time (46 +/- 24 versus 66 +/- 33 minutes, p less than 0.002). Complications were limited to transient pericarditis (three patients), one iliac artery dissection, and cardiac tamponade probably caused by catheter repositioning in the coronary sinus (one patient). An electrophysiological study was repeated in 50 of the 55 successful cases at a mean of 9 +/- 5 months. This study was normal in 48 of 50 (96%) patients. CONCLUSIONS: Low-energy DC ablation is safe and effective treatment for accessory pathways in children and adults. The long-term outcome is excellent as documented by electrophysiological restudy.

Low energy direct current ablation in patients with the Wolff-Parkinson-White syndrome: clinical outcome according to accessory pathway location.

Forty-five patients with the Wolff-Parkinson-White syndrome underwent direct current (DC) ablation using a low energy power source (Cardiac Recorders). Anodal shocks of 10-40 joules were given to either a 6 French quadripolar catheter (Bard), a 7 French bipolar contoured catheter (Bard), or a 7 French deflectable catheter with a 4-mm distal electrode (Mansfield). The indifferent electrode consisted of a large patch that was positioned under the left scapula. There were 26 males and 19 females, with a mean age of 34 years (range 9-67). Accessory pathways were located in the left free wall in 30 patients (67%) and were posteroseptal in 15 patients (33%). The shortest ventriculoatrial interval during mapping (89 +/- 21 msec), the mean cumulative amount of energy per patient (322 +/- 283 joules), and the mean CK-MB rise (45 +/- 30 units, normal 0-30 units) were not significantly different between both groups. Ablation was successful in 29/30 patients (97%) with a left free-wall accessory pathway, and in 13/15 patients (87%) with a posteroseptal accessory pathway. All three patients with failure of ablation had multiple accessory pathways, and two of these patients had Ebstein's anomaly. Patients with left free-wall and posteroseptal accessory pathways, respectively, differed significantly in terms of: total session time (4.1 +/- 1 hours vs 5.3 +/- 1.3, p = 0.0001), total procedure time for ablation (2.6 +/- 0.8 hours vs 3.2 +/- 1.2, P = 0.02), and fluoroscopy time (46 +/- 24 min vs 64 +/- 29, P = 0.006). In 13 patients (29%) with a concealed accessory pathway, these variables were not significantly different from patients with overt preexcitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of diltiazem on symptomatic and asymptomatic episodes of ST segment depression occurring during daily life and during exercise.

BACKGROUND: Silent myocardial ischemia is an adverse prognostic marker in patients with coronary disease; however, controlled data on the effect of treatment are sparse and contradictory, and the relations among the occurrence of ST segment depression, drug efficacy, and heart rate are unclear. METHODS AND RESULTS: Sixty patients with stable coronary artery disease, a positive treadmill exercise test and asymptomatic ST segment depression on ambulatory electrocardiographic recording were assessed in a multicenter, double-blind, placebo-controlled, cross-over trial. Treadmill exercise tests and 72-hour electrocardiographic recordings were obtained at the end of two 2-week treatment periods with sustained-release diltiazem 180 mg b.i.d. or equivalent placebo. Episodes of asymptomatic ST depression decreased by 50% or more in 70% of the patients from a median number of 4.5 (range, 0-19) to 1.5 (range, 0-13) (p = 0.0001); their cumulative duration also decreased from 78.5 (range, 0-60) to 24.5 (range, 0-411) minutes (p = 0.001). No circadian variation was found in the efficacy of diltiazem. The occurrence of ischemic type ST segment depression was modulated by changes in heart rate rather than by absolute heart rate. Diltiazem also improved exercise test end points but to a lesser extent. Time to ST segment depression increased to 341 +/- 148 from 296 +/- 154 seconds (p = 0.005). Although less frequent with diltiazem administration (45 versus 54 patients, p less than 0.03), exercise-induced ST depression was more often asymptomatic (98% versus 72% of patients, p less than 0.0001). CONCLUSIONS: Diltiazem reduces the frequency and severity of ischemic type ST depression in patients with stable coronary artery disease.

Physical and dynamic characteristics of DC ablation in relation to the type of energy delivery and catheter design.

We evaluated and compared the in vitro characteristics of direct current ablation using high energy ablation (Hewlett-Packard defibrillator) and a new form of low energy ablation (low energy ablation power supply, Cardiac Recorders, UK). Two new catheters with a large distal electrode have been recently introduced for catheter ablation: a low energy 7F bipolar catheter (Bard) with a contoured distal electrode, and a 7F deflectable catheter with a 4-mm tip (Mansfield). In vitro studies were carried out in a large tank filled with physiological saline while recording voltage, current, and pressure. High speed cinematography at 32,000 frames per second (Cordin, Utah) was done to assess the dynamic behavior of the vapor globe with both systems of energy delivery. We evaluated shocks of 50, 100, 150, 200, and 300 joules with the conventional system, and shocks of 10, 15, 20, 30, and 40 joules with the new system, and also compared the effects of varying catheter design with both systems of energy delivery. The conventional system using high energy showed significant arcing and increases in pressure. Low energy direct current ablation produces nonarcing shocks with 20 joules or less, and significantly less vapor globe and gas formation during arcing shocks, with a shorter duration of increase in pressure. This new system using low energy direct current may reduce the risk and complications reported with high energy ablations.

In vitro and in vivo effects within the coronary sinus of nonarcing and arcing shocks using a new system of low-energy DC ablation.

DC shocks within the coronary sinus have been abandoned because of the risk of cardiac rupture and tamponade. Catheter ablation using DC energy to electrodes straddling the ostium of the coronary sinus, when used clinically, has been reported to result in cardiac tamponade in as many as 16% of patients. A new system of energy delivery maximizes voltage while decreasing the undesirable effects caused by barotrauma. This system includes 1) a low-energy ablation power supply with a brief time-constant capacitive discharge that delivers up to 40 J and 3,000 V and 2) a low-energy ablation catheter with a contoured distal electrode. We performed in vitro and in vivo studies of this new system and compared arcing shocks with nonarcing shocks. Ablations were performed using unipolar distal shocks (D) and unipolar shocks to both electrodes made electrically common (P-D). In vitro studies were done in a large tank filled with physiological saline while recording voltage, current, and pressure. High-speed cinematography (32,000 frames/sec) of shocks of 10-40 J permitted detailed analysis of the vapor globe. Anodal shocks of less than 20 J showed no arcing or only minimal vapor globe formation. For D and P-D anodal shocks of 40 J, the diameters of the vapor globe were 31 and 22 mm, respectively, corresponding to pressure recordings of 11 and 4.9 atm. The pressure rise lasted less than 50 mu sec. In vivo studies involved 18 dogs that received nonarcing shocks (one to six shocks of 15 J) and 18 dogs that received arcing shocks (one to three shocks of 40 J). Each group was divided between D and P-D shocks; catheter ablation was performed at a mean +/- SEM distance of 2.94 +/- 0.92 cm within the coronary sinus. All dogs tolerated the procedure without cardiac rupture or tamponade. When killed 2-4 days later, the dogs had edema and hyperemia or hemorrhage in the area of the coronary sinus. We compared the effects of multiple (three to six) nonarcing shocks with the effects of one to three arcing shocks. Disruption or rupture of the coronary sinus within the epicardial fat space occurred in two of 12 dogs (17%) with multiple nonarcing shocks but in 13 of 18 dogs (72%) with arcing shocks (p less than 0.003). Occlusion of the coronary sinus occurred in two of 12 dogs (17%) with multiple nonarcing shocks and in nine of 18 dogs (50%) with arcing shocks (p less than 0.06).(ABSTRACT TRUNCATED AT 400 WORDS)