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Pedro Adragão

Publications and source records attributed to Pedro Adragão.

16 recordsLinked to original sources
PubMed2004

Atrial tachycardia ablation in a patient with double outlet right ventricle corrected by surgery.

The development of surgical and percutaneous techniques for treatment or palliation of congenital heart disease has prolonged survival in these patients and has increased late complications, particularly arrhythmias. Such arrhythmias are more frequently refractory to medical therapy, requiring percutaneous ablation. We present the clinical case of a 14-year-old child with complex congenital heart disease (double outlet right ventricle) who underwent two corrective surgeries (Rastelli operation and subsequent replacement of the homograft in the conduit connecting the right ventricle to the pulmonary artery; ventricular septal defect closure and tricuspid valve repair). After the second surgery the patient presented with wide complex syncopal tachycardia, refractory to medical therapy. Electrophysiologic study (EPS) identified an isthmus-dependent atrial flutter that was successfully treated by radiofrequency (RF) ablation (a linear block was created along the cavo-tricuspid isthmus). Three months later a new episode of tachycardia occurred, but without syncope. The second EPS revealed an atrial tachycardia originating from the lateral wall of the right atrium, which was treated by ablation with focal application of RF energy. Four months after the last EPS the child remains free of arrhythmic symptoms, under no anti-arrhythmic therapy.

Adolescent↗
PubMed2004

Atrial flutter ablation: correlation between isthmic activation times and flutter cycle.

BACKGROUND: Ablation of typical atrial flutter relies on the suppression of electrical conduction along the cavo-tricuspid isthmus. Bidirectional isthmus block is a criterion of successful ablation and is associated with the presence of different activation times on each side of the ablation line. OBJECTIVE: The aim of this study was to determine whether the difference in isthmic activation times correlates with the length of the atrial flutter cycle. POPULATION AND METHODS: We studied 31 patients with typical atrial flutter (93.6% male, mean age 66 +/- 9 years) who underwent successful ablation during tachycardia. CARTO electroanatomic mapping was used to confirm diagnosis of isthmus-dependent atrial flutter, guide the ablation line creation and assess its efficacy. At the end of the procedure, a three-dimensional activation map of the right atrium was constructed, under pacing from the coronary sinus ostium (with a 500 ms cycle). Activation times on the lateral (right) and septal (left) sides of the ablation line were measured. The difference between these two activation times was termed the difference in isthmic activation times (delta IAT), and was compared to the flutter cycle length. RESULTS: Mean activation times were 173.7 +/- 34.3 ms on the lateral border of the ablation line and 19.1 +/- 12.5 ms on the septal border. Mean delta IAT was 154.6 +/- 27.8 ms and mean atrial flutter cycle length was 257.5 +/- 30.6 ms. delta IAT and flutter cycle length were significantly correlated (r = 0.503, p = 0.0039). The linear regression equation that best described this result was: delta IAT = 37 + (0.46 x flutter cycle). CONCLUSION: After atrial flutter ablation, a difference in isthmic activation times of more than half the flutter cycle length was associated with isthmus conduction block.

Aged↗
PubMed2003

Epicardial radiofrequency applications: in vitro and in vivo studies on human atrial myocardium.

OBJECTIVES: To obtain a better understanding of tissue damage induced in human atria by epicardial radiofrequency ablation and its correlation with intra-tissue temperatures measured sub-epicardially and sub-endocardially. METHODS: Radiofrequency (RF) currents were delivered to human atrial tissues using experimental set-ups to simulate surgical RF epicardial ablation at 80, 85 and 90 degrees C. Sub-endocardial and sub-epicardial temperatures were measured with thermocouples during the ablations. Twelve samples from in vitro epicardial ablations were histologically assessed. Localized RF epicardial ablations at same temperatures were performed on 38 mitral patients with concomitant atrial fibrillation (AF) before full cardiopulmonary bypass and samples histologically assessed. All patients had endocardial RF ablation at 70 degrees C to treat AF. RESULTS: In vitro Sub-endocardial temperatures were lower than 50 degrees C except on thin atria (approximately 2-3 mm) in ablations at 80 and 85 degrees C and on thicker atria (approximately 5 mm) in ablations at 90 degrees C. Lesions measured 0.85-1.98 mm, all showed epicardial and myocardial damage but none were transmural. Mitral patients: Lesions measured 0.38-3.25 mm and 13/25 induced at 70 degrees C, 2/8 at 80 degrees C, 1/4 at 85 degrees C and 0/1 at 90 degrees C were confined to the epicardium leaving the myocardium undamaged. The remaining had damage of the epicardium and of variable portions of the myocardium, and three were transmural. CONCLUSIONS: The application temperature and the intra-tissue temperature are not the sole factors that determine lesion depth. The thickness and the composition of the epicardium and of the myocardium are major determinants in the formation of the lesion.

Adolescent↗
PubMed2003

Identification of pulmonary vein foci by non-contact mapping in patients with paroxysmal atrial fibrillation.

AIMS: Ectopies from the pulmonary veins may cause paroxysmal atrial fibrillation and their discrete ablation may be curative. In the absence of focal activity during the procedure, identification of target sites with conventional techniques is difficult. We investigated the feasibility of non-contact mapping (EnSite) for identification and successful ablation of pulmonary vein foci in such cases. METHODS AND RESULTS: We studied 7 patients with idiopathic paroxysmal atrial fibrillation referred for percutaneous ablation and not presenting spontaneous or inducible atrial premature beats during the procedure. An EnSite balloon catheter and an ablation catheter (NaviStar) were placed inside the left atrium. The ablation catheter was also used for electroanatomic mapping (CARTO) of specific sites. Multiphasic pulmonary vein potentials were detected on virtual electrograms and tagged on the non-contact map and confirmed with conventional mapping. The procedural endpoint was elimination or dissociation of the multiphasic potential. Non-contact mapping identified 13 foci of multiphasic potentials in the seven patients (5 foci were initially identified by EnSite), and discrete ablation suppressed 9 of them (69%). Six months later, 4 of the 5 patients in whom all foci were suppressed remain asymptomatic, in sinus rhythm, under no medication. CONCLUSION: In patients with paroxysmal atrial fibrillation and no ectopic activity during electrophysiological study virtual electrograms may complement conventional techniques in detecting hidden pulmonary vein foci and may be used to evaluate ablation efficacy.

Aged↗
PubMed2003

Electrical disconnection versus anatomical isolation of the pulmonary veins: two sides of the same treatment for atrial fibrillation?

OBJECTIVE: There are currently two techniques for percutaneous electrical isolation of the pulmonary veins (PV): anatomical isolation and electrical disconnection. The aim of the present study was to assess the continuity and circumferential extension of the radiofrequency applications necessary for PV electrical disconnection in order to evaluate the differences between this technique and anatomical isolation. METHODS: We studied 9 patients with paroxysmal atrial fibrillation who underwent PV electrical disconnection. The electrophysiologic study was performed with a decapolar circular catheter (Lasso) introduced in the PV ostia and a mapping and ablation catheter (CARTO). Ablation was performed following the activation sequence of PV potentials. Using the CARTO system we evaluated the number of applications, their distribution in quadrants, and the maximum distance between contiguous and opposite RF applications. We assessed the number of veins with circumferential applications. The number of applications and maximum distance between contiguous applications were compared to the maximum distance between opposite applications. RESULT: A total of 26 PV were isolated, including 9 right superior, 5 right inferior, 6 left superior and 6 left inferior. On average more than 10 applications were necessary, with a heterogeneous distribution. In 80.8% of the PVs the maximum distance between contiguous application was less than 1 cm and maximum distance between opposite application were highest in the right superior PV and lowest in the right inferior PV. The applications were circumferential in 80.8% of the disconnections. The number of RF applications was significantly higher in PVs with greater distances between opposite applications (correlation coefficient 0.51; p=0.008). No relation was found between maximum distances in contiguous and opposite applications (correlation coefficient r=0.13; p=NS). CONCLUSION: Electrical disconnection was achieved in the great majority of cases with circumferential applications, similarly to anatomical isolation. However, the heterogeneous distribution of the applications implies the existence of areas that need a greater number of applications and that can only be identified during electrophysiologic study. Therefore, rather than two aspects of the same treatment for atrial fibrillation, electrical disconnection and anatomical isolation complement each other in the achievement of effective PV isolation.

Adult↗
PubMed2003

Ablation of atrial fibrillation in mitral valve disease patients: five year follow-up after percutaneous pulmonary vein isolation and mitral balloon valvuloplasty.

BACKGROUND: The association between atrial fibrillation (AF) and mitral valve disease is frequent. Isolation of the pulmonary veins by radiofrequency energy applications performed intraoperatively has been proposed for patients with AF in whom mitral valve surgery has been indicated. Balloon mitral valvuloplasty is currently the preferred procedure for patients with mitral stenosis and a favorable valve anatomy. AIM: To evaluate the short- and long-term results of percutaneous pulmonary vein isolation for the treatment of AF in patients with mitral stenosis undergoing balloon mitral valvuloplasty. METHODS: Five patients (four male and one female, age 43 +/- 4 years) underwent balloon mitral valvuloplasty concomitant with pulmonary vein isolation between August 1996 and February 1997. These patients had permanent AF, diagnosed 31 +/- 12 months previously; their mitral valve area was 1.0 +/- 0.25 cm2 and their left atria measured 54 +/- 5 mm. Balloon mitral valvuloplasty was performed via a transseptal approach, and then four ablation lines were created in the left atrial posterior wall to encircle all four pulmonary veins. Radiofrequency applications lasted 45 seconds each, and aimed at a maximum preset temperature of 65 degrees C. Electrical cardioversion was performed at the end of the procedure. RESULTS: Mitral valve area increased 1.0 +/- 0.3 cm2 after valvuloplasty. The number of radiofrequency applications per patient was 37 +/- 3, and the average duration of the entire treatment was 131 +/- 28 minutes. Fluoroscopy time averaged 32 +/- 12 minutes. All patients were discharged in sinus rhythm, and mitral flow Doppler evaluation at one month showed a biphasic pattern in all cases, with the A wave measuring 70 +/- 15 cm/sec. Three patients maintained sinus rhythm at five-year follow-up. Of these patients, one had developed a left atrial flutter at four-year follow-up and underwent ablation. The remaining two patients presented AF at five year follow-up. CONCLUSIONS: Percutaneous isolation of the pulmonary veins concomitant with balloon mitral valvuloplasty had suppressed AF in 60% of patients by five-year follow-up.

Adult↗
PubMed2002

Electronanatomical mapping and ablation of atrial tachycardias with the CARTO system.

UNLABELLED: Variable success rates in the ablation of atrial tachycardias using conventional electrophysiology have been achieved. There is no precise relation between P wave morphology in surface ECG and atrial electrophysiology, and this fact makes it more difficult to locate ectopic atrial foci. The CARTO system creates atrial activation maps that relate an anatomical location to an electrical potential. The aim of this study was to evaluate the efficacy of CARTO guided radiofrequency (RF) ablation of atrial foci. The population consisted of 10 consecutive patients with atrial tachycardia resistant to more than 2 drugs, 7 female, mean age 45 +/- 12 years. CARTO activation maps were constructed based on atrial tachycardia or premature beats. Radiofrequency energy was applied to the earliest activation zone. Immediate success was defined as suppression of ectopic atrial activity. Ectopic foci were located on the ostium of the coronary sinus (3 patients), crista terminalis (1 patient), right atrial appendage (1 patient), interatrial septum (1 patient) and in the pulmonary veins (4 patients). The activation maps contained 85 +/- 35 points. The number of RF applications ranged from 1 to 11 (mean 4). Immediate and 6 month success rate was 90%. We were not able to treat one patient with a focus in the right atrial appendage. No attempt was made to limit procedure or fluoroscopy time in our study. Nonetheless all procedures lasted less than 150 min, and fluoroscopy times were less than 30 minutes. CONCLUSIONS: The CARTO system precisely located ectopic atrial foci, allowing a high success rate in the ablation of focal atrial tachycardias.

Adult↗
PubMed2002

Atrial fibrillation and effective refractory period of the pulmonary vein ostia.

BACKGROUND: The pathogenesis of atrial fibrillation (AF) is not completely understood. The role of pulmonary veins (PV) in AF initiation is documented, and the recent demonstration of persistent fibrillatory activity in an isolated PV suggests that the PV play a role in the maintenance of AF. OBJECTIVE: Since AF is facilitated by multiple reentry circuits in atrial tissue with short effective refractory periods (ERP) and prolonged conduction times, we investigated whether PV have shorter ERP compared with the left atrium (LA). POPULATION AND METHODS: The study population consisted of five male patients, between 45 and 78 years of age, with normal sized LA; three had coronary artery bypass surgery (and no previous history of atrial arrhythmias) and two had paroxysmal lone AF refractory to antiarrhythmic drugs and were referred for percutaneous ablation with radiofrequency energy. In the surgical patients, epicardial bipolar pacing wires were inserted in the PV ostia and LA roof at the end of the procedure. Post-operatively, the pacing wires were used to determine atrial thresholds and ERP in the PV ostia and LA roof. In the AF patients, atrial thresholds and ERP at these locations were obtained with the mapping/ablation catheter before and after PV isolation. ERP were determined with a basic pacing cycle length of 500 ms and a single extrastimulus with an initial coupling interval of 350 ms, gradually decreased (10 ms at a time) until atrial capture failure or AF induction. RESULTS: ERP in the LA roof were longer than 210 ms. The shortest ERP was always obtained in a PV ostium, with the shortest in the left PV ostia. The ERP values of the right inferior PV most resembled those of the LA roof. In patients referred for ablation, AF was induced when PV ostia with ERP shorter than 200 ms were stimulated. CONCLUSION: In the present study, the ERP of PV ostia were shorter than LA ERP, possibly explaining not only the presence of ectopic foci in the PV ostia, but also sustained fibrillatory activity in isolated PV, despite conversion of the atria to sinus rhythm. This fact may also explain the higher success rate and the preference for PV isolation in AF ablation.

Aged↗
PubMed2002

Evaluation of bilateral pulmonary vein isolation for the treatment of atrial fibrillation: value of postoperative electrophysiological study.

OBJECTIVE: To evaluate electrophysiological changes after bilateral pulmonary vein isolation in patients undergoing mitral valve surgery and to relate the clinical outcome at 1-year follow-up with the results of the postoperative electrophysiological study. METHODS: Prospective study of patients with atrial fibrillation undergoing bilateral pulmonary vein isolation using radiofrequency energy and concomitant mitral valve surgery. Pulmonary vein isolation was performed with a heptapolar catheter. Each set of up to 7 simultaneous applications aimed at a maximal duration of one minute and a maximal preset temperature of 70 degrees C. Energy delivery (< 150 watts) was controlled by thermosensors located on each electrode. Before hospital discharge, all patients presenting sinus rhythm underwent an electrophysiological study, using epicardial pacing wires placed during surgery. Isolated areas were compared to the non-isolated left atrium with respect to electrogram amplitudes and atrial capture thresholds. At one-year follow up, cardiac rhythm was assessed in all patients and correlated with the results of the postoperative electrophysioloical study. RESULTS: The study population consisted of 20 patients with mitral valve disease (mean age 59 +/- 11 years), chronic atrial fibrillation present for 0.5 to 18 years and dilated left atria (55 +/- 11 mm assessed by M-mode echocardiography). The radiofrequency procedure added, on average, 7 minutes (3 to 17) to the duration of the mitral valve surgery. No patient died or suffered surgical complications. Eleven patients presented sinus rhythm before hospital discharge. The electrogram amplitude inside the isolated zones was less than 25% of that in nonisolated areas (0.3 +/- 0.2 mV versus 2.1 +/- 1.7 mV, p = 0.002). Atrial capture thresholds were significantly higher for the isolated areas (13.5 +/- 9.3 mA versus 8.5 +/- 4.0 mA; p < 0.05). At one-year follow-up, nine patients maintained atrial fibrillation, nine remained in sinus rhythm and two lost sinus rhythm to atrial fibrillation. In both these patients, the reduction in electrogram amplitude inside the isolated zones was similar to that of the remaining patients discharged in sinus rhythm. However, postoperative electrophysiological studies in these patients showed that atrial capture thresholds for isolated areas had not increased significantly (8 mA and 6 mA, respectively). CONCLUSION: Rhythm at discharge after bilateral pulmonary vein isolation tends to remain at one-year follow up. Radiofrequency-induced modifications in electrogram amplitudes may be less important than increases in pacing thresholds of isolated zones with respect to maintenance of sinus rhythm.

Atrial Fibrillation↗
PubMedDate not supplied

Epicardial electroanatomical mapping for intraoperative evaluation of bilateral pulmonary vein isolation.

UNLABELLED: Eight patients (pts; 2 female, 58 +/- 12 yrs) with paroxysmal atrial fibrillation (AF) (duration 39 +/- 20 months) underwent AF surgery, with concomitant myocardial revascularization in 2 pts and myomectomy in 1 (HOCM). AF was idiopathic in the remaining 5 pts. AF surgery consisted of bilateral isolation of the pulmonary veins (PV) using radiofrequency (RF) energy applied epicardially by a heptapolar catheter (Thermaline) in 5 pts and by a new system (Atricure) in 3 pts. For the former, each set of 7 simultaneous applications aimed at a maximum duration of 2 + 2 min., preset temperature 80 degrees C and output 150 watts. With the new system, bipolar applications were carried out; energy delivery was controlled by impedance monitoring and applications were ended after abrupt, sustained elevation of impedance. Epicardial bipolar voltage mapping (CARTO) was performed before and after each RF procedure. Using the navigator catheter, points were recorded at the insertion of each PV and at the non-isolated left atrial posterior wall. The amplitude of the local electrograms (LE) was measured before and after RF applications. If the LE amplitude inside the isolated zone was not 0.1 mV and not reduced by > 80%, a second application was performed. A maximum of 2 epicardial applications were carried out in each pt and if the final result was unsatisfactory, further endocardial applications were performed. RESULTS: Baseline LE amplitudes were > 1 mV in all cases. Successful isolation of right PVs was achieved in 7 pts, after one set of applications in 5 and a second set in 2. Left PV isolation required 2 sets of epicardial applications in all pts, being successful in only 2; 4 pts (one with associated myomectomy and 3 with idiopathic AF) received endocardial applications. Overall, bilateral PV isolation was achieved in 5 pts. CONCLUSIONS: CARTO bipolar voltage mapping is a fast, simple means for evaluation of epicardial PV isolation.

Atrial Fibrillation↗