Radiofrequency Ablation Of Atrial Flutter Research Articles

Prevalence of previous history of atrial fibrillation in patients referred for ablation of atrial flutter

Introduction: Atrial fibrillation (AF) and atrial flutter (AFL) are frequently associated. The aim of the study was to look for the prevalence of previous history of AF in patients referred for radiofrequency ablation of AFL and the possible causes. Methods: 1061 patients, 819 males, 242 females, mean age 64±12 years were referred for ablation of recurrent or poorly-tolerated typical AFL. Clinical history, previous AF, data of echocardiography, was collected. Patients were followed from 3 months to 10 years (mean 3±3 years). Antiarrhythmic drugs (AAD) were stopped after ablation except in patients with previous AF before ablation. Results: 336 patients had presented at least one episode of sustained AF (>1 min) before AFL ablation (group I). The prevalence of AF in this population was high (32%). These patients were compared to remaining patients without know AF (group II). Ages of group I and II were similar (65±11 vs 64±12 years). They were more frequently females in group I (27%) than in group II (24%) (p<0.04). The presence of associated heart disease (HD) was less frequent in group I (67.5%) than in group II (89%) (p< 0.0001).When the nature of HD was analysed, the frequency of dilated cardiomyopathy (10 vs 10%), hypertensive disease (22 vs 23%), valvular HD (10 vs 14%) did not differ. Group I had less respiratory failure (4 vs 13%) (p<0.0001), congenital HD (2 vs 5.6%) (p<0.005), and ischemic HD (14 vs 21%) (p<0.004) than group II. Diabetes and previous strokes were as frequent in group I (10, 4%) as in group II (14, 3%). Presentation with rhythmic cardiomyopathy or 1/1AFL was as frequent in group I (7, 11%) as in group II (9.5, 8%). Most patients of group I received an AAD (AA) (87 vs 66%) (p<0.0001), mainly a class I AAD (45 vs 9%) (p<0.0001). After AFL ablation, AF occurrence was more frequent in group I despite AAD maintaining (31%) than in group II (22%) (p<0.0044). Treatments of AF as ablation of His bundle and pacemaker or ablation of AF were more frequently used in group I (3.5, 5%) than in group II (0.8%,p<0.0001, 0.3%,p<0.0011). However cardiac mortality was similar in both groups (5 vs 8%). Conclusions: There is an high prevalence of history of AF in patients referred for ablation of AFL (32%). Paradoxically, age and presence of HD were not favoring causes. Females without HD were at higher risk to have both arrhythmias than males. Their risk of subsequent AF was higher than in patients without previous AF, but cardiac mortality was similar.

Obstructive Sleep Apnea in Patients With Typical Atrial Flutter: Prevalence and Impact on Arrhythmia Control Outcome

The clinical yield of cavotricuspid isthmus (CTI) radiofrequency ablation of atrial flutter (AF) is limited by a high incidence of atrial fibrillation (AFib) in the long term. Among other acknowledged variables, the association of obstructive sleep apnea (OSA) could favor incomplete arrhythmia control in this setting. We assessed the impact of CPAP in reducing the occurrence of AFib after CTI ablation.Consecutive patients with AF who were undergoing CTI ablation were screened for OSA. Relationship of the following variables with the occurrence of AFib during follow-up (12 months) was investigated: CPAP initiation, hypertension, BMI, underlying structural heart disease, left atrial diameter, and AFib documentation prior to ablation.We prospectively included 56 patients (mean age: 66 (± 11) years; 12 female patients), of whom 46 (82%) had OSA and 25 (45%) had severe OSA. Twenty-one patients (38%) had AFib during follow-up after CTI ablation. Both freedom from AFib prior to ablation and CPAP initiation in those patients without previously documented AFib at inclusion were associated with a reduction of AFib episodes during follow-up (P = .019 and P = .025, respectively). Inversely, CPAP was not protective from AFib recurrence when this arrhythmia was documented prior to ablation (P = .25).OSA is a prevalent condition in patients with AF. Treatment with CPAP is associated with a lower incidence of newly diagnosed AFib after CTI ablation. Screening for OSA in patients with AF appears to be a reasonable clinical strategy.

Right ventricular diverticulum

A 57-year-old man presented with fever, chills, and productive cough. He underwent successful radiofrequency ablation of atrial flutter 3 months prior to current presentation. His work up included a chest X-ray that showed consolidated pneumonia of right lung with a parapneumonic effusion. A chest CT scan obtained for further assessment was notable for an incidental finding of a right ventricular outpouching in the infero-apical area ( Panel A ). Differential diagnosis consisted …

Atrioventricular block during radiofrequency catheter ablation of atrial flutter: incidence, mechanism, and clinical implications

To evaluate the incidence, mechanism, and clinical implications of atrioventricular (AV) block during catheter radiofrequency (RF) ablation of the cavotricuspid isthmus (CTI). Although RF ablation of atrial flutter is the most frequently performed ablation procedure, data on the incidence and significance of an AV block occurring during the procedure are scarce. Consecutive patients (n=845, 73.5% male) undergoing CTI ablation (913 procedures) between 1998 and 2010 were studied. Data on the occurrence of complete AV block (lasting≥3 s) during the procedure were prospectively collected. Sixteen (1.9%) patients experienced AV block, 12 during delivery of RF pulses (Group 1) and 4 (Group 2) during manipulation of catheters in the cardiac chambers. The AV block was short lived (<1 min), located in the AV node, and associated with septal isthmus RF lines in 11 Group 1 patients. It was long-lasting and led to pacemaker implantation in one Group 1 patient. Atrioventricular blocks had an infranodal location in four Group 2 patients, all of whom had a pre-existing complete left bundle branch block (LBBB). One Group 2 patient had an AV block during his two ablation procedures. Permanent pacemakers were implanted in five (0.6%) patients (one from Group 1 and four from Group 2). Atrioventricular blocks requiring pacemaker implantation following administration of RF pulses at the CTI are rare (0.12%). The occurrence rate of AV block related to the procedure and requiring pacemaker implantation is, however, not negligible (0.6%) and mostly affects patients with a pre-existing complete LBBB.

Atrial flutter after non-congenital cardiac surgery: Incidence, predictors and outcome

BackgroundAtrial arrhythmias (AAs) occur frequently after cardiac surgery. However, most authors do not differentiate postoperative atrial fibrillation (AF) from atrial flutter (AFL). Our study sought to investigate the incidence and predictors of AFL following non-congenital cardiac surgery, and the long-term outcome of this arrhythmia. Methods and resultsWe conducted an observational, retrospective, single-centre study. Among 821 patients in sinus rhythm (SR) before non-congenital cardiac surgery, AFL occurred in 42 patients (5.1%) and AF in 77 (9.4%). Independent predictors of AAs were older age (odds ratio (OR): 1.06, 95% confidence interval (CI): 1.01–1.11, p=0.02), low postoperative hemoglobin level (OR: 0.43, CI: 0.29–0.63, p<0.0001) and long cross-clamp time (OR: 1.02, CI: 1.002–1.037, p=0.03). Compared to AF patients, those with AFL were younger (67±10 versus 72±8years, p=0.005) and less likely to have valve surgery (57% versus 76%, p=0.03). After conversion to SR, of 41/42 patients with AFL, 5 (12%) developed AFL and 5 (12%) had AF within a mean follow-up of 9.6±8.4months: only 32% of patients were on long-term antiarrhythmic therapy and 5% had radiofrequency ablation of AFL in the early postoperative period. ConclusionAFL following non-congenital cardiac surgery is not frequent. Compared to patients in AF, those with AFL are younger and less likely to have valve surgery. After conversion of AFL to SR, recurrence rate of AAs is relatively low. Therefore, AFL occurring in this setting does not require systematic catheter ablation in the postoperative period.

Proximity of Right Coronary Artery to Cavotricuspid Isthmus as Determined by Computed Tomography

Radiofrequency ablation of atrial flutter is a commonly performed procedure. Ablation success depends upon complete transmural atrial tissue injury to achieve bidirectional cavotricuspid isthmus (CTI) block. Transmural ablation increases risk of injury to the adjacent right coronary artery (RCA). Distance between the RCA and the endocardium within the CTI area is not well described. We aimed to perform in vivo measurements of the distance between the CTI area and adjacent RCA. Thirty-three consecutive patients underwent electrocardiogram-gated contrast-enhanced computed tomography. CTI area was divided into nine segments based on three common catheter locations (paraseptal, central, and lateral or 5, 6, and 7 o'clock) and ventricular to atrial ablation line. Mean age was 64 ± 11 years and 97% of the participants were male. Paraseptal, central, and lateral measurements at the tricuspid annulus ridge showed endocardial to RCA distance 9 ± 3, 6 ± 2, and 5 ± 3 mm, respectively (range 2-17 mm). Corresponding measurements for the ventricular side were 5 ± 3, 4 ± 2, and 4 ± 2 mm and atrial side measurements were 3 ± 2, 3 ± 2, and 3 ± 3 mm. Distance was ≤2 mm in 14% of segments on the ventricular side and 39% of segments on the atrial side. Paired t-test showed significant difference (P < 0.001) between tricuspid annulus ridge measurements and adjacent atrial or ventricular measurements. Distance between endocardium and RCA lumen is reduced in areas adjacent to the tricuspid annulus ridge.

First experience of percutaneous radio-frequency ablation for atrial flutter and atrial fibrillation in a patient with HeartMate II left ventricular assist device

We report the first case of percutaneous radio-frequency (RF) ablation procedure in a patient implanted with a HeartMate II left ventricular assist device for refractory heart failure. This procedure was performed for poorly tolerated recurrent atrial arrhythmias. No harmful consequence happened during or after the procedure despite the potential electromagnetic interferences existing between the RF delivery and the functioning of the device.

216 Gastroparesia as a frequent complication after extensive left atrial ablation for atrial arrhythmias: a consecutive series of 100 procedures

Various gastro-intestinal complications have been reported after atrial fibrillation (Afib) radiofrequency (RF) ablation. The purpose of this study was to prospectively evaluate the incidence of esogastric injuries after Afib RF ablation. Between June 2007 and April 2009, all patients (pts) in whom Afib/left atrial flutter RF ablation was performed, underwent a systematic upper gastro-intestinal endoscopy 24 hours after the procedure. Endoscopic findings were classified as likely related to the procedure, potentially related or unrelated. 100 ablation procedures were performed in 77 pts using a 4 mm irrigated-tip RF catheter with temperature set to 45°C. Ablation consisted in antral isolation of pulmonary veins (PVI) in 63 cases (63%; maximum power: 30W), associated with creation of roof and left isthmus lines in 14 (14%;35W), and additional left atrial fragmented electrograms ablation in 23 (23%;35W). Esogastric endoscopy found gastroparesia in 6 cases (6%), considered as likely related to the ablation and due to vagal injury. Among these cases, 4 had left atrial fragmented electrograms ablation (p<0.001). In 3 PVI cases (3%), localized esophagus erythema was also considered as likely related to the ablation procedure. In 5 cases with either Mallory Weiss-like syndrome (n=3) or circumferential esophagus erythema (n=2), RF induced lesions could not be fully ruled out. In 3 cases, esophageal lesions were likely due to pre-operative trans-esophageal echocardiography (2 hematomas and 1 proximal ulceration). In 45 cases (45%), endoscopic abnormalities were considered as unrelated to the ablation (gastritis, n=18; Barret's esophagus, n=7; hiatal hernia, n=14). Endoscopy was normal in 43 cases (43%). In this prospective study, the incidence of asymptomatic esogastric injuries likely related to RF ablation was fairly high (9%). Gastroparesia was the main complication and was significantly associated with extensive left atrial ablation.

Incremental Pacing for the Diagnosis of Complete Cavotricuspid Isthmus Block During Radiofrequency Ablation of Atrial Flutter

Complete conduction block of the cavotricuspid isthmus (CTI) reduces atrial flutter recurrences after ablation. Incremental rapid pacing may distinguish slow conduction from complete CTI conduction block. Fifty-two patients (67 +/- 9 years) undergoing 55 CTI ablation procedures were included. With ablation, double potentials (DPs) separated by an isoelectric line of > or =30 ms were obtained. Incremental atrial pacing (600-250 ms) was performed from coronary sinus (CS) and low lateral right atrium (LLRA). A <20 ms increase in the DPs distance during incremental pacing was indexed as complete CTI block. In 8 patients, an initial <20 ms DPs distance increase was noted; direct complete isthmus block was suggested and no additional ablation performed. In the remaining, the CTI line was remapped for conduction gaps and additional radiofrequency energy pulses applied. Complete block, as indexed by incremental pacing, occurred in 46 of 55 procedures, with one flutter recurrence (follow-up 8 +/- 2 months): DPs interval variation of 116 +/- 20 to 123 +/- 20 ms (CS), P = 0.21; and 122 +/- 25 to 135 +/- 35 ms (LLRA), P = 0.17. The remaining 9 patients (persistent rate-dependent DPs increase) presented 3 flutter recurrences, P = 0.01: DP distance from 127 +/- 15 to 161 +/- 18 ms (CS), P < 0.001; and 114 +/- 24 to 142 +/- 10 ms (LLRA), P = 0.007. Incremental pacing distinguishes complete CTI block from persistent conduction. Such identification, accompanied by additional ablation to achieve block, should minimize flutter recurrences after ablative therapy.

Three-Dimensional Transesophageal Echocardiography of Pacemaker Endocarditis

![Figure][1] [![Graphic][3] ][3][![Graphic][4] ][4] A62-year-old man developed pleuritic chest pain, fever, chills, and diaphoresis 3 days after radiofrequency ablation for atrial flutter. He had a history of nonischemic cardiomyopathy and had a biventricular pacemaker-

Effect of Radiofrequency Ablation of Atrial Flutter on the Natural History of Subsequent Atrial Arrhythmias

Effect of Radiofrequency Ablation of Atrial Flutter on the Natural History of Subsequent Atrial Arrhythmias

Effect of Radiofrequency Ablation of Atrial Flutter on the Natural History of Subsequent Atrial Arrhythmias

Flutter Ablation and Subsequent Arrhythmia. Patients with atrial flutter (AFL) treated medically are at high risk for subsequent development of atrial fibrillation (AF). Whether curative radiofrequency ablation of AFL can modify the natural history of arrhythmia progression is not clear. We aimed to determine whether ablation of AFL decreases the subsequent development of AF in patients without previous AF. Patients with AFL as the sole atrial arrhythmia were selected from patients who underwent successful AFL ablation at Mayo Clinic between 1997 and 2003 (N = 137). The cohort was divided by presence (n = 50) or absence (n = 87) of structural heart disease. A control group comprised 59 patients with AFL and no history of paroxysmal AF, who received only medical therapy. Occurrence of AF after AFL ablation was compared among study groups and controls. Symptomatic AF occurred in 49 patients during 5 years of follow-up after AFL ablation, with similar frequency in both study groups. The cumulative probability of paroxysmal and chronic AF was similar in controls and each study group. By multivariate analysis, the AFL ablation procedure carries significant risk of AF occurrence during follow-up. Fifty patients discontinued antiarrhythmic drugs after AFL ablation, and the rate of cardioversions decreased. Successful ablation of AFL does not improve the natural history of atrial arrhythmia progression; postablation AF is frequent. This suggests that AFL may be initiated by bursts of AF and that in the absence of AFL substrate the AF continues to progress.

Incidence of Propofol Infusion Syndrome During Noninvasive Radiofrequency Ablation for Atrial Flutter or Fibrillation

Incidence of Propofol Infusion Syndrome During Noninvasive Radiofrequency Ablation for Atrial Flutter or Fibrillation

Atrial Fibrillation–Atrial Flutter Interactions

An appreciation of the article by Moreira et al in the current issue of Circulation 1 requires an understanding of the close interrelationship between atrial fibrillation (AF) and atrial flutter (AFL). These authors have understood this interrelationship and applied it to their data to advance the approach to both AF and AFL ablation. Key to this understanding is the recognition that cavotricuspid isthmus (CTI)–dependent AFL almost always develops from antecedent AF of variable duration.2–5 This is because in almost all instances, it is during the AF that a functional line of block (LoB) necessary for the development of AFL forms between the superior and inferior vena cavae. This LoB acts as a critical lateral boundary that prevents short-circuiting of the AFL reentrant circuit. Thus, in the vast majority of instances, without preceding AF, there can be no AFL. The most recent additional support of this concept comes from the report by Ellis et al,6 which found that of 363 patients who presented with only CTI-dependent AFL and who underwent CTI ablation, long-term follow-up (mean of 39±11 months) demonstrated newly recognized AF in 82%. It also should be noted that, as Moreira et al1 recognize, in some patients, a LoB between the vena cavae may be fixed (ie, anatomic) rather than functional. In such patients, AF may not be required for AFL to develop. Article p 2786 As Moreira et al1 further recognize, their report does not answer all the questions about the interrelationships of AF and AFL as they relate to AF ablation, …

Radio-Frequency Ablation of Atrial Flutter: Long-Term Results and Predictive Value of Cavo-Tricuspid Isthmus Bidirectional Block as Determined by a Simplified Technique

Objectives: Complete bidirectional cavo-tricuspid isthmus (CTI) block is mandatory for radio-frequency (RF) ablation of typical atrial flutter (AF). CTI block can be assessed by a simplified method using two catheters and the technique of differential pacing, but long-term results in large series are poorly known. Methods: CTI RF ablation was performed in 255 consecutive patients with typical AF, using one quadripolar catheter, and the ablation catheter, in association with the technique of differential pacing. Results: Procedural success, as defined by documentation of complete bidirectional CTI block using limited activation mapping, positive differential pacing together with termination of ongoing AF, was achieved in 80% of patients. AF recurred in 37 patients (14%) over a mean follow-up period of 15 ± 9 months. Two hundred and forty-one patients (94%) were finally cured, with 1.1 procedures/patient. The recurrence rate was related to the achievement of complete CTI bidirectional block (12% vs. 29%, p = 0.01). Conclusions: Long-term results of CTI ablation, employing a simplified method using the differential pacing technique, are similar to those for the standard methods using multipolar catheters. Therefore, this technique compares favorably to other established methods for such common RF procedures, especially due to its lower cost.

Incidence of Propofol Infusion Syndrome during Noninvasive Radiofrequency Ablation for Atrial Flutter or Fibrillation

Propofol infusion syndrome is first manifest by unexplained metabolic acidosis. Its incidence is unknown. Charts of all patients undergoing nonsurgical, catheter radiofrequency ablation for atrial flutter or fibrillation from 1999 through 2001 at Mayo Clinic Rochester, who received propofol and had an arterial blood gas drawn during the procedure, were reviewed retrospectively for metabolic acidosis, prospectively defined as base excess -2 or less. Of 301 radiofrequency ablation cases, 55 had an arterial blood gas. Virtually all radiofrequency ablation patients received propofol, so they could not be used as nonpropofol controls. Instead, all carotid endarterectomy patients in 2000 who did not receive propofol and had an arterial blood gas drawn after anesthetic induction and before surgical incision were used as a comparator group. In propofol radiofrequency ablation patients with no apparent cause of metabolic acidosis besides propofol, 13 of 55 (24%) had base excess of -2 or less, versus 22 of 267 carotid patients (8.2%) (P<0.01). Maximal negative base excess was -4.2+/-1.7 in these propofol patients and was not correlated with propofol dose, age, or fluid dose, versus base excess of -3.2+/-1.5 in carotid patients (P>0.05). Propofol patients received prolonged anesthetics (7 h) and high-dose propofol (20 mg/kg). This is the first incidence estimate of metabolic acidosis during prolonged propofol infusion and suggests that it is not rare. The study is limited by its retrospective nature and by the lack of baseline arterial blood gas data and will require confirmation by prospective study.

The Difference of Left Atrial Volume Index: Can It Predict the Occurrence of Atrial Fibrillation after Radiofrequency Ablation of Atrial Flutter?

important. We investigated variables predicting this evolution in ablated patients without a previous atrial fibrillation history. Materials and Methods：Thirty-six patients (Male=28) who were diagnosed as atrial flutter without previous atrial fibrillation history were enrolled in this study. Group 1 (n=11) was defined as those who developed atrial fibrillation after atrial flutter ablation during 1 year follow-up. Group 2 (n=25) was defined as those who has not occurred atrial fibrillation during same follow-up term. Echocardiogram was performed to all patients. We measured left atrial size, left ventricle end diastolic and systolic dimension, ejection fraction and left atrial volume index before and after ablation of atrial flutter. The differences of each variables were compared and analyzed between two groups. 1) Results：The preablation left ventricular ejection fraction (preLVEF) and postablation left ventricular ejection fraction (postLVEF) are 54±14%, 56±13% in group 1 and 47±16%, 52±13% in group 2. The differences between each two groups are statistically insignificant (2.2±1.5 in group 1 vs 5.4±9.8 in group 2, p=0.53). The preablation left atrial size (preLA) and postablation left atrial size (postLA) are 40±4 mm, 41±4 mm in group1 and 44±8 mm, 41±4 mm in group 2. The atrial sizes of both groups were increased but, the differences of left atrial size between two groups before and after flutter ablation were statistically insignificant (0.6±0.9

Success rate of catheter ablation in atrial flutter: Comparison of a 4- or 5-mm tip electrode catheter with an 8-mm tip electrode catheter

Radio frequency (RF) energy is capable of interrupting the reentrant circuit of atrial flutter and curing the arrhythmia. The development of 8-mm tip catheter provides more tissue damage and has offered the promise of improved success. The purpose of our study was to determine if the acute and long-term success with the 8-mm tips were superior to the 4- or 5-mm tips. The outcomes of the first 20 patients in whom an 8-mm tip catheter was used were compared with the previous 20 patients in whom a 4-or 5-mm tip catheter was used. Procedural (acute) ablation success was defined by creation of bi-directional isthmus block. Long-term success was defined as the prevention of clinically evident atrial flutter (AFl) as determined by the absence of symptoms or maintenance of sinus rhythm on electrocardiogram, six months to one year after the procedure. Compared to the 4- or 5-mm tip, the 8-mm catheter tip was associated with a reduced ablation duration {22.3 +/- 16 versus 11.5 +/- 5 min (p = 0.0078)}, a lower mean number of ablations {13.5 +/- 9.9 versus 6.8 +/- 2.9 (p = 0.0065)} and a reduced procedure time {1.8 +/- 0.7 versus 1.1 +/- 0.5 h (p = 0.0032)}. Acute success was 95% in the 4- or 5-mm group versus 80% in the 8-mm group (p = NS), but long-term success was higher in the 8-mm group than the 4- or 5-mm group (87.5 versus 63.2%, p = 0.0436). Eight-millimeter tip catheters for AFl shorten procedure time, reduce the duration and number of ablations and accomplish bi-directional block when compared with smaller tipped catheters. The long-term success rate is better with the 8-mm tips and should be the preferred catheter for RF ablation of AFl.

The radiofrequency ablation of atrial flutter

This care study presents the management of a 66-year-old man with typical atrial flutter. Complications of atrial flutter are hear t failure and stroke. The management of this man involved rate control, anticoagulation, cardiovascular risk reduction and referral for radiofrequency ablation. Radiofrequency ablation is a safe and effective first-line treatment for typical atrial flutter and has a number of advantages over long-term pharmacological management. Issues such as quality of life and patient choice also need to be addressed by health professionals when formulating management plans.

A Randomized Clinical Trial of Continuous Flow Nitrous Oxide and Nalbuphine Infusion for Sedation of Patients During Radiofrequency Atrial Flutter Ablation

In patients with common atrial flutter (CAF), radiofrequency ablation (RFA) causes discomfort. Patients undergoing RFA often feel pain which is difficult to control as the mechanisms are unclear. Inhaled nitrous oxide (N2O) is a potent sedative-analgesic-anxiolytic agent that may relieve anxiety and discomfort during CAF ablation. In a prospective randomized study, the effect of Inhaled N2O was compared with that of intravenous sedation with Nalbuphine during CAF ablation in 76 patients (64 +/- 13 years, 56 men). We used a 24 pole mapping catheter around the tricuspid annulus and a 8-mm tip ablation catheter for each patient. Forty-two patients (group 1) underwent radiofrequency (RF) application to the cavotricuspid isthmus 5 minutes after the beginning of inhalation of a (50% N2O/50% O2) mixture. Thirty-four patients (group 2), underwent the first RF application 15 minutes after the end of an infusion of Nalbuphine (20 mg delivered over 15 minutes). Ablation-related anxiety and discomfort were assessed using a visual analog scale (VAS) ranging from 0 to 100 mm, with 0 correlating to the statement "no pain at all" and 100 with "the worst possible pain." The VAS score was determined at the end of each application. The number of RF applications (group 1; 10 +/- 8 vs group 2; 11 +/- 6, P = NS) and procedure duration (group 1; 75 +/- 53 minutes vs group 2; 72 +/- 45 minutes, P = NS), were similar for the two groups. N(2)O sedation compared with nalbuphine infusion reduced VAS for anxiety (10 mm +/- 8 vs 58 mm +/- 22, P < 0.05) and for discomfort (18 mm +/- 9 vs 45 mm +/- 34, P < 0.01), respectively. Although there was more frequent vomiting in group 1; 7 of 42 (17%) than in group 2; 3 of 34 (9%), P < 0.05, patients were less likely to have hypotension during the procedure 1 of 42 (2.5%) versus 4 of 34 (12%), P < 0.05, respectively. Inhalation of a (50% N2O/50% O2) mixture during RF ablation for atrial flutter is a safe and efficient way to reduce anxiety and discomfort caused by RF applications.