Safety, feasibility and cost of outpatient radiofrequency catheter ablation of accessory atrioventricular connections

AbstractObjectives. The purpose of this study was to evaluate prospectively the safety, feasibility and cost of performing radiofrequency catheter ablation of accessory atrioventricular (AV) connections on an outpatient basis in 137 cases.Background. The efficacy and low complication rate of radiofrequency ablation as performed in the hospital suggested that it might be feasible to perform it on an outpatient basis.Methods. In 100 cases (73%) performed between September 1, 1991 and April 20, 1992, patients met criteria for treatment as outpatients. Reasons for exclusion were age <13 or >70 years (4), anteroseptal location of the accessory AV connection (5 patients), obesity (>30% of ideal body weight) (4 patients) or clinical indication for hospitalization (24 patients). Patients with only venous punctures had a recovery period of 3 h and those with arterial punctures had a recovery period of 6 h. There were 63 men and 32 women (5 patients underwent two ablation procedures >1 month apart), with a mean age ± SD of 36 ± 13 years. The pathway was left-sided in 67 cases and right-sided or posteroseptal in 33.Results. The procedure was successful in 97 of 100 cases, with a mean procedure duration of 99 ± 42 min. In 70 cases the patient was discharged the day of ablation, and in 30 cases the patient required a short (≤18-h) overnight stay because the procedure was completed too late in the day for recovery in the outpatient facility. The mean duration of observation was 4.8 ± 1.5 h for outpatients and 15 ± 1.4 h for patients who underwent overnight hospitalization. At follow-up study, two patients had a clinically significant complication; both had a femoral artery pseudoaneurysm detected ≥1 week after the procedure and both required surgical repair. Thirty consecutive patients (22 outpatients and 8 hospitalized overnight) undergoing catheter ablation after January 1, 1992 were chosen for a cost analysis. The mean cost of the procedure was $10,183 ±$1,082.Conclusions. The majority of patients undergoing radiofrequency catheter ablation of an accessory AV connection can be treated safely on an outpatient basis

Comparison of Fixed Burst Versus Decremental Burst Pacing for Termination of Ventricular Tachycardia

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72440/1/j.1540-8159.1993.tb01531.x.pd

Recurrence of conduction in accessory atrioventricular connections after initially successful radiofrequency catheter ablation

AbstractThe purpose of this study was to characterize the incidence and clinical features of accessory pathway recurrence after initially successful radiofrequency catheter ablation and to identify variables correlated with recurrence. Radiofrequency ablation was performed with a 7F deflectable tip catheter with a large (4 mm in length) distal electrode. Left-sided accessory patthways were approached through the left ventricle and right-sided pathways by way of the right atrium. Patients were included in the study if 1) they had an initially successful procedure, defined as the absence of accessory pathway conduction immediately after ablation, and 2) had undergone a 3-month follow-up electrophysiologic test or had documented recurrence of accessory pathway conduction.Accessory pathway conduction recurred after initially successful ablation in 16 (12%) of 130 patients. Almost half (7 of 16) of these recurrences were in the 1st 12 h after ablation, and the last occurred after 106 days. Return of delta waves on the electrocardiogram (ECG) or spontaneous paroxysmal supraventricular tachycardia was the initial indication of recurrence in 15 of the 16 patients. Two patients with manifest accessory pathways exhibited recurrence with exclusively concealed accessory pathway conduction.Accessory pathways ablated from the tricuspid anulus (right free wall or septal accessory pathways) had a much higher recurrence rate (24%) than did those on the mitral anulus (6%). Fourteen of 15 patients have had successful repeat accessory pathway ablation after the initial recurrence. After a mean follow-up period of 4 ± 3 months, there have been no repeat recurrences of any of these accessory pathways.It is concluded that accessory pathway recurrence is infrequent after successful radiofrequency catheter ablation. All but one episode of recurrence was diagnosed clinically, suggesting that routine follow-up electrophysiologic testing in asymptomatic patients is not warranted. Because manifest accessory pathways may recur with retrograde conduction only, patients with palpitation after ablation should have electrophysiologic testing even if no delta waves are seen on the ECG. The success rate of ablation after recurrence (93%) is comparable to that achieved at the initial session, suggesting that return of accessory pathway function should not be a contraindication to a repeat attempt

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.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30894/1/0000563.pd

Effect of operator experience on outcome of radiofrequency catheter ablation of accessory pathways

Radiofrequency catheter ablation of accessory pathways has been shown to be safe and effective, and is rapidly becoming the treatment of choice for patients with the Wolff-Parkinson-White syndrome or paroxysmal supraventricular tachycardia involving a concealed accessory pathway.1-6 Because radiofrequency catheter ablation requires skill in mapping and catheter manipulation, the outcome is at least in part operator-dependent. The purpose of this study was to determine the effect of operator experience on the outcome of radiofrequency catheter ablation of accessory pathways by analyzing the changes in efficacy and duration of the procedure as experience increased.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30824/1/0000486.pd

The economic burden of unrecognized vasodepressor syncope

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. 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 $3,763 +/- 3,820 and$2,678 (range: 0 to $16,606) respectively. Six patients underwent no major diagnostic tests prior to referral and, therefore, the cost of major diagnostic testing was zero in these patients. In the remaining patients, the mean and median costs of diagnostic testing per patient were$4,704 +/- 3,713 and $3,777 (range:$1,025 to $16,606) respectively. The results of this study demonstrate that a diagnosis of vasodepressor syncope can be established clinically in approximately 20$16,000 of unnecessary diagnostic testing. A greater awareness of the clinical features of vasodepressor syncope may, therefore, result in significant economic savings.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31087/1/0000764.pd

Determinants of impedance during radiofrequency catheter ablation in humans

Radiofrequency catheter ablation has become the treatment of choice for selected patients with paroxysmal supraventricular tachycardia due to atrioventricular node reentry or the Wolff-Parkinson-White syndrome. 1-3 Despite encouraging results described in several series, the optimal energy delivery strategy has not been defined. Lesion formation occurs during radiofrequency ablation as the result of resistive heating at the electrode-tissue interface.4 The magnitude of heat generation is proportional to power density at the point of contact.5 Electrosurgical units currently being used for radiofrequency ablation have a low source impedance and therefore approximate constant voltage sources. With such a device, one preselects a given output voltage. Applied power is proportional to the square of this output voltage and is inversely proportional to the load impedance imposed by the ablation catheter, patient and indifferent electrode. Thus, the effectiveness of any given energy application may be influenced by the impedance of the system. This study characterizes impedance during radiofrequency catheter ablation in humans, and defines the relation between clinical and ablation parameters, and measured impedance.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30105/1/0000477.pd

Comparison of automated quantitative coronary angiography with caliper measurements of percent diameter stenosis

Measurement of coronary artery stenosis is an invaluable tool in the study of coronary artery disease. Clinical trials and even day-to-day decision making should ideally be based on accurate and reproducible quantitative methods. Quantitative coronary angiography (QCA) using digital angiographic techniques has been shown to fulfill these requirements. Yet many laboratories have abandoned visual analysis in favor of the intermediate quantitative approach involving hand-held calipers. Thus, the purpose of this study was to determine the relation between QCA and the commonly used caliper measurements. Percent stenosis was assessed in 155 lesions using 3 techniques: QCA, caliper measures from a 35-mm cine viewer (cine) and caliper measures from a video display (CRT). Good overall correlation was noted among the 3 different techniques (r &gt;-0.72). Both of the caliper methods underestimated QCA for stenosis &gt;=75% (p &lt;=0.001) and overestimated stenosis &lt;75% (p &lt; 0.05). Reproducibility assessed in 52 lesions by independent observers showed QCA to be superior (r = 0.95) to either of the caliper measurements (cine: R = 0.63; CRT: R = 0.73). Therefore, the commonly used caliper method is not an adequate substitute for QCA because overestimation of noncritical stenoses and underestimation of severe stenoses may occur and the measurements have poor reproducibility. These factors definitely preclude its use in rigorous clinical trials. Moreover, since they do not appear to overcome known deficiencies of visual analysis, caliper measurements for day-to-day clinical use must also be seriously questioned.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28572/1/0000375.pd

Relation between impedance and endocardial contact during radiofrequency catheter ablation

Lesion size during radiofrequency catheter ablation in patients with paroxysmal supraventricular tachycardia (PSVT) is thought to be related to multiple factors, including contact pressure at the catheter-endocardial interface. Therefore a predictor of contact pressure at a potential target site for ablation might be useful. In this study 25 patients underwent duplicate 2 W applications of radiofrequency energy with the catheter in poor and firm contact with the right ventricular endocardium after successful ablation treatment for PSVT. The mean age of the patients was 44 +/- 15 years. Fifteen patients underwent slow pathway ablation for atrioventricular nodal reentrant tachycardia, and 10 patients underwent ablation for an accessory pathway. The mean impedance for low-energy applications in firm contact (139 +/- 24 ohms) was 22% +/- 13% greater (p 0.0001) than in poor contact with the right ventricle (113 +/- 16 ohms). The maximum impedance was 27% greater when the catheter was in firm (147 +/- 28 ohms) rather than poor contact (116 +/- 16 ohms), with the endocardium (p 0.0001). These results suggest that higher impedance measurements may be obtained with low-energy applications of 2 W when the ablation catheter is in firm contact with the endocardium.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31909/1/0000862.pd

Safety and cost of outpatient radiofrequency ablation of the slow pathway in patients with atrioventricular nodal reentrant tachycardia

Radiofrequency ablation of atrioventricular (AV) nodal reentrant tachycardia has been shown to be an effective and safe treatment and to have a significant cost advantage over other forms of therapy.1 In studies reported to date, patients were hospitalized for 2 to 10 days after slow pathway ablation to monitor for possible complications or a recurrence of the tachycardia.2,3 A previous study reported that radiofrequency ablation of accessory pathways can be performed safely on an outpatient basis,4 but no prior studies evaluated the safety of outpatient radiofrequency ablation of the slow pathway in patients with AV nodal reentrant tachycardia. Therefore, the purpose of this study was to evaluate the safety and cost of performing radiofrequency catheter ablation of the slow AV nodal pathway on an outpatient basis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30435/1/0000057.pd