Rafel El-Atassi

Diagnosis and cure of the Wolff-Parkinson-White syndrome or paroxysmal supraventricular tachycardias during a single electrophysiologic test

BACKGROUND We conducted this study to determine the feasibility of an abbreviated therapeutic approach to the Wolff-Parkinson-White syndrome or paroxysmal supraventricular tachycardia, in which the diagnosis is established and radiofrequency ablation carried out during a single electrophysiologic test. METHODS One hundred six consecutive patients were referred for the management of documented, symptomatic paroxysmal supraventricular tachycardias (66 patients) or the Wolff-Parkinson-White syndrome (40 patients). All agreed to undergo a diagnostic electrophysiologic test and catheter ablation with radiofrequency current. No patient had had such a test previously. RESULTS Among the 66 patients with paroxysmal supraventricular tachycardias, the mechanism was found to be atrioventricular nodal reentry in 46 (70 percent) (typical in 44 and atypical in 2), atrioventricular reciprocating tachycardia involving a concealed accessory pathway in 16 (24 percent), atrial tachycardia in 2 (3 percent), and noninducible paroxysmal supraventricular tachycardia in 2 (3 percent). A successful long-term outcome was achieved in 57 of 62 patients (92 percent) with paroxysmal supraventricular tachycardia in whom ablation was attempted and in 37 of 40 patients (93 percent) with the Wolff-Parkinson-White syndrome. The only complications were one instance of occlusion of the left circumflex coronary artery, leading to acute myocardial infarction, and one instance of complete atrioventricular block. The mean (+/- SD) duration of the electrophysiologic procedures was 114 +/- 55 minutes. CONCLUSIONS The diagnosis and cure of paroxysmal supraventricular tachycardia or the Wolff-Parkinson-White syndrome during a single electrophysiologic test are feasible and practical and have a favorable risk-benefit ratio. This abbreviated therapeutic approach may eliminate the need for serial electropharmacologic testing, long-term drug therapy, antitachycardia pacemakers, and surgical ablation.

Radiofrequency catheter ablation of ventricular tachycardia in patients with coronary artery disease.

BackgroundRadiofrequency (RF) ablation of idiopathic ventricular tachycardia (VT) has been demonstrated to be highly efficacious, but the efficacy of RF ablation of VT in patients with coronary artery disease has been unknown. Therefore, the purpose of this study was to determine the feasibility of RF ablation of VT in patients with coronary artery disease. Methods and ResultsFifteen consecutive patients with coronary artery disease and a history of myocardial infarction underwent an attempt at RF ablation of 16 hemodynamically stable monomorphic VTs that had been documented clinically on a 12-lead ECG and that had not been successfully managed by pharmacological or device therapy. One VT was incessant, five occurred more than 25 times, and the remainder occurred two to 20 times. An additional four VTs that had not been documented clinically also were targeted for ablation. The mean age of the patients was 68±7 years (±|SD), and their mean left ventricular ejection fraction was 0.27±0.08. The mean cycle length of the 20 VTs targeted for ablation was 438±82 msec. Ablation sites were selected based on endocardial activation mapping, pace mapping, identification of an isolated middiastolic potential, or concealed entrainment. Sixteen of the 20 VTs (80%o) were successfully ablated in 11 of 15 patients (73%), using a mean of 4.2±3 applications ofRF energy, and no recurrences of the ablated VTs occurred during 9.1±3.3 months of follow-up. The mean duration of the ablation procedures was 128±30 minutes. No complications occurred in any of the patients. ConclusionThe results of this study demonstrate that RF ablation of hemodynamically stable is feasible as adjunctive therapy in selected patients with coronary artery disease.

Radiofrequency catheter ablation of accessory atrioventricular connections in 250 patients. Abbreviated therapeutic approach to Wolff-Parkinson-White syndrome.

Background The purpose of this study was to report the results and complications of radiofrequency catheter ablation of accessory atrioventricular (AV) connections by using an abbreviated approach aimed at minimizing the duration of the procedure. Methods and Results Two hundred fifty consecutive patients with the Wolff-Parkinson-White syndrome or paroxysmal supraventricular tachycardia involving a concealed accessory AV connection underwent catheter ablation with the use of radiofrequency current. In 179 of the 250 patients, catheter ablation was performed at the time of an initial electrophysiology test. Two hundred thirty-five patients had one accessory AV connection and 15 patients had two or more. One hundred eighty-three accessory AV connections were manifest and 84 were concealed. One hundred sixty-one were located in the free wall of the left ventricle, 47 were in the right free wall, 44 were posteroseptal, 10 were anteroseptal, and five were intermediate septal. The time required for catheter placement, the diagnostic component of the electrophysiology test, and the ablation procedure was recorded for each patient, as was the total duration of fluoroscopy. A follow-up electrophysiology test was performed 2–3 months after the ablation procedure. Ninety-four percent of patients had all accessory AV connections successfully ablated and remained free of symptomatic tachycardia during a mean follow-up of 10±4 months. Two hundred nineteen patients (88%) had all accessory AV connections ablated during the initial attempt at catheter ablation. Mean duration of the entire procedure was 134±75 minutes. Procedure duration was longest in patients with multiple accessory AV connections, shortest in patients with intermediate septal accessory AV connections, and similar in all other locations. A nonfatal complication occurred in nine patients (4%). Conclusions The results of this study indicate that catheter ablation of accessory AV connections with radiofrequency current can be performed safely and expeditiously in a majority of patients and confirm in a large series the feasibility of catheter ablation at the time of an initial diagnostic electrophysiology test. This abbreviated therapeutic approach avoids the need for electropharmacological testing, long-term antiarrhythmic drug therapy, and surgical therapy in the majority of patients with the Wolff-Parkinson-White syndrome or with symptomatic tachycardias involving accessory AV connections.

Radiation exposure during radiofrequency catheter ablation of accessory atrioventricular connections.

BackgroundCatheter ablation of accessory atrioventricular (AV) connections has been demonstrated to be effective in more than 85% of patients. One of the risks of this procedure is radiation exposure during the fluoroscopic imaging necessary to guide catheter manipulation. The objective of the present study was to measure the radiation received by patients and physicians during radiofrequency catheter ablation and to estimate the resultant somatic and genetic risks. Methods and ResultsRadiation exposure to patients and physicians was measured during attempts at radiofrequency catheter ablation of accessory AV connections in 31 consecutive patients. Radiation exposure was measured using thermoluminescent sensors placed on the patient and on the physician. Somatic and genetic risks were estimated based on the radiation levels recorded using these sensors. The durations of fluoroscopy and of the catheter ablation procedure were recorded for each patient. Catheter ablation was successful in 28 of 31 patients (90%). Mean + SD duration of fluoroscopy was 44 ± 40 minutes. The largest patient radiation dose was measured over the ninth vertebral body posteriorly (median, 7.26 rem [roentgen equivalents man]; range, 0.31–135.7 rem). Median radiation dose to the thyroid was 0.46 rem (range, 0.06–7.26 rem), and median radiation dose to the posterior iliac crest was 2.43 rem (range, 0.01–8.3 rem). The greatest radiation dose to the operator was recorded at the left hand (99 mrem). Mean radiation dose to the operators eyes was 28 mrem. ConclusionsRadiofrequency catheter ablation of accessory AV connections may result in significant radiation exposure to the patient and to the physician. Each hour of fluoroscopic imaging is associated with a lifetime risk of developing a fatal malignancy of 0.1% and a risk of a genetic defect of 20 per 1 million births. Although these risks must be recognized, they are relatively small compared with the risks associated with alternate approaches to management, including no therapy, antiarrhythmic drug therapy, and surgery.

Relation between efficacy of radiofrequency catheter ablation and site of origin of idiopathic ventricular tachycardia

The results of radiofrequency catheter ablation of ventricular tachycardia (VT) in patients without structural heart disease are reported. Particular attention was focused on the relation between efficacy and the site of origin of the VT. Eighteen consecutive patients (5 women and 13 men; mean age 41 +/- 13 years) with idiopathic VT underwent catheter ablation using radiofrequency energy. Sites for radiofrequency energy delivery were selected on the basis of pace mapping. A follow-up electrophysiologic test was performed 1 to 3 months after the ablation procedure. Twenty VTs were induced. Radiofrequency catheter ablation was successful in eliminating all 10 VTs originating from the right ventricular outflow tract, and 5 of 10 from other sites in the left or right ventricle. There were no complications. The duration of ablation sessions was shorter, the frequency of identifying a site resulting in an identical pace map was higher, and the efficacy of catheter ablation was greater for VTs originating from the right ventricular outflow tract than for those from other locations. The results of this study demonstrate that radiofrequency catheter ablation of idiopathic VT is safe and effective. The efficacy of the procedure is dependent on the site of origin of the VT, with the efficacy being greater for VTs originating from the outflow tract of the right ventricle than for those from other locations.

Temperature monitoring during radiofrequency catheter ablation of accessory pathways.

BACKGROUND Animal studies have suggested that the temperature of the electrode-tissue interface during radiofrequency catheter ablation accurately predicts lesion size. The purpose of the current study was to evaluate the utility of continuous temperature monitoring during radiofrequency catheter ablation in patients with Wolff-Parkinson-White syndrome. METHODS AND RESULTS Twenty patients with manifest preexcitation were included in the study. The ablation catheter was positioned on the ventricular side of the mitral annulus for left-sided accessory pathways and on the atrial side of the tricuspid annulus for right-sided and septal accessory pathways. A thermistor imbedded in the distal electrode of the ablation catheter allowed continuous temperature monitoring during each energy application. To define the relation between power and temperature, radiofrequency current was applied several times at each site using outputs of 20, 30, 40, and 50 W. The accessory pathways were successfully ablated in each of the 20 patients. Because of marked variability in the efficiency of heating between sites, power output did not predict temperature. However, at any given site, there was a positive dose-response relation between power and temperature. Radiofrequency energy applications on the atrial side of the tricuspid annulus produced lower temperatures than did applications on the ventricular side of the mitral annulus (49 +/- 7 versus 60 +/- 16 degrees C, p = 0.0001). Transient block in the accessory pathways occurred at a mean of 50 +/- 8 degrees C, whereas permanent block was seen at a mean of 62 +/- 15 degrees C (p = 0.0001). Less than half of the applications at outputs < or = 40 W produced temperatures adequate to interrupt accessory pathway conduction. An abrupt rise in impedance caused by coagulum formation occurred only at temperatures between 95 and 100 degrees C. CONCLUSIONS Temperature monitoring may facilitate radiofrequency catheter ablation of accessory pathways. By adjusting power output to ensure that adequate but not excessive temperatures have been achieved, a rise in impedance can be avoided and the total number of energy applications and procedure duration may be reduced.

Electrogram criteria for identification of appropriate target sites for radiofrequency catheter ablation of accessory atrioventricular connections.

BackgroundCatheter ablation of accessory atrioventricular (AV) connections using radiofrequency current has been demonstrated to be effective in the majority of patients with the Wolff-Parkinson-White syndrome or paroxysmal supraventricular tachycardia involving a concealed accessory AV connection. However, electrogram criteria have not been established to guide attempts at radiofrequency catheter ablation. Methods and ResultsThe characteristics of local electrograms recorded at successful and unsuccessful sites of radiofrequency catheter ablation were determined in 132 patients. Electrograms recorded at a total of 438 sites were analyzed: 338 recorded during ablation of 90 manifest accessory AV connections and 100 recorded during ablation of 44 concealed accessory AV connections. During ablation of manifest accessory AV connections, the independent predictors of outcome were electrogram stability (p<0.001), the interval between activation of the ventricular electrogram and onset of the QRS complex (p<0.001), and the presence of an accessory AV connection potential (p<0.001). Radiofrequency energy delivery at sites demonstrating stable electrograms, a probable or possible accessory AV connection potential, and activation of the local ventrical electrogram before the onset of the QRS complex had a 57% probability of success compared with a 3% probability of success at sites without these features. During ablation of concealed accessory AV connections, the independent predictors of outcome were electrogram stability (p=0.02), the presence of an accessory AV connection potential (p=0.05), and the presence of retrograde continuous electrical activity (p=0.04). Sites demonstrating a stable local electrogram, an accessory AV connection potential, and retrograde continuous electrical activity had an 82% probability of success compared with only a 5% probability of success at sites demonstrating none of these features. ConclusionsThe local electrogram parameters of greatest importance in predicting the success or failure of radiofrequency catheter ablation of accessory AV connections are electrogram stability, the presence of an accessory AV connection potential, and the timing of ventricular activation relative to the QRS complex (for manifest accessory AV connections) or retrograde continuous electrical activity (for concealed accessory AV connections). Awareness of these variables during attempts at radiofrequency catheter ablation of accessory AV connections may minimize the number of unnecessary applications of radiofrequency energy.

A randomized, prospective comparison of anterior and posterior approaches to radiofrequency catheter ablation of atrioventricular nodal reentry tachycardia.

BackgroundTwo different techniques have been developed for radiofrequency catheter ablation of typical atrioventricular nodal reentry (AVNRT). Lesions made anteriorly near the apex of the triangle of Koch usually eliminate fast pathway function, whereas lesions made posteriorly near the ostium of the coronary sinus selectively affect slow pathway function. The current study compares the safety, efficacy, and electrophysiological effects of these two techniques in a prospective, randomized fashion. Methods and ResultsFifty consecutive patients with typical AVNRT were randomly assigned to receive radiofrequency lesions either anteriorly (N=22) or posteriorly (N=28). If the initial approach failed to eliminate inducibility ofAVNRT after 1 hour or 10 applications of radiofrequency energy, the alternative ablation technique was used. Patients underwent repeat electrophysiological testing 48 hours and 3 months after ablation. The primary success rates of the anterior and posterior techniques were similar (55% versus 68%, p=NS). All of the patients who failed the initial approach were successfully treated by the alternative technique without developing high-grade atrioventricular block. One patient developed right bundle branch block during an anterior lesion, and another patient developed complete atrioventricular block as the result of a posterior lesion. ConclusionsThe posterior approach to radiofrequency catheter modification of the atrioventricular node is as effective as the anterior approach, and both techniques are associated with a low risk of complications. As long as AVNRT persists, it appears safe to cross over from one technique to the other.

A prospective randomized comparison of direct current and radiofrequency ablation of the atrioventricular junction

OBJECTIVES The purpose of this study was to compare direct current and radiofrequency ablation of the atrioventricular (AV) junction in a prospective randomized fashion. BACKGROUND Catheter ablation of the AV junction can be performed using either direct current shocks or radiofrequency energy. To date, these two techniques have never been compared prospectively or in a randomized study. METHODS Forty patients with drug-refractory uncontrolled atrial fibrillation-flutter (38 patients) or inappropriate sinus tachycardia (2 patients) were randomly assigned to undergo direct current ablation (20 patients) using up to four shocks of 200 to 300 J or radiofrequency ablation (20 patients) using up to 15 applications of 16 to 25 W for 30 s. If complete AV block was not successfully induced, the ablation procedure was repeated using the alternate type of energy. A rate-responsive ventricular pacemaker was implanted in each patient. The intrinsic escape rhythm was evaluated 15 min, 2 days and 3, 6 and 12 months after ablation. RESULTS Persistent complete AV block was successfully induced during the first ablation session in 13 (65%) of 20 patients randomly assigned to undergo direct current ablation, compared with 19 (95%) of 20 patients randomly assigned to undergo radiofrequency ablation (p < 0.05). Each patient whose first ablation attempt failed had a successful outcome with the alternate type of energy. The overall efficacy of radiofrequency ablation (26 [96%] of 27 patients) was significantly greater than that of direct current ablation (14 [67%] of 21 patients, p < 0.01). The duration of the direct current and radiofrequency ablation sessions did not differ significantly. The mean peak plasma creatine kinase MB fraction concentration was significantly higher after direct current ablation (58 +/- 29 IU/liter) than after radiofrequency ablation (2 +/- 2 IU/liter) (p < 0.001). An escape rhythm was present 15 min after ablation in an equal proportion of patients undergoing direct current and radiofrequency ablation (78% and 85%, respectively, p = 0.6). An escape rhythm was present in all patients 3, 6 and 12 months after ablation. The mean escape rhythm cycle length 15 min after direct current ablation (2,074 +/- 677 ms) was significantly longer than that 15 min after radiofrequency ablation (1,460 +/- 294 ms) (p < 0.05); however, the mean escape rhythm cycle lengths did not differ significantly at 2 days or 3, 6 or 12 months after ablation. Immediate arrhythmic complications did not occur after either procedure. One patient died suddenly 6.5 months after direct current ablation. CONCLUSIONS Radiofrequency ablation of the AV junction is more efficacious and safer than direct current ablation and should be the preferred method for inducing complete AV block in patients who are appropriate candidates for ablation of AV conduction.

The economic burden of unrecognized vasodepressor syncope

BACKGROUND The objective of this study was to describe the cost of prior diagnostic evaluation in patients referred for evaluation of syncope whose history was typical of vasodepressor syncope. METHODS AND RESULTS Thirty consecutive patients who were referred for evaluation of syncope of undetermined origin and whose history was highly suggestive of vasodepressor syncope participated in this study. These 30 patients represented 19% of 158 patients referred for evaluation of syncope during the period of enrollment. All patients had positive results of an upright-tilt test, confirming the diagnosis of vasodepressor syncope. At the time of evaluation, the type and results of all diagnostic tests that had been performed prior to referral were recorded for each patient. The cost of diagnostic testing was then determined based on the 1991 cost of these tests at the University of Michigan Medical Center. A mean of 4 +/- 2 major diagnostic tests were performed before referral to the University of Michigan Medical Center. The mean and median costs of diagnostic testing per patient prior to referral were