Atrioventricular node reentrant tachycardia: Remote magnetic navigation ablation versus manual ablation - impact on operator fluoroscopy time.

INTRODUCTION AND AIMS: Remote magnetic navigation systems have demonstrated benefits in the ablation of difficult substrates. Their role in the ablation of atrioventricular nodal reentrant tachycardia (AVNRT), however, has only been studied in small patient series. The aim of this study was to compare the results of AVNRT ablation using magnetic navigation, in a center where every procedure is performed with this system, with manual ablation. METHODS: We selected 139 consecutive patients undergoing AVNRT ablation with magnetic navigation by a single operator between January 2009 and June 2016 and compared them to a group of 101 consecutive patients undergoing manual ablation in the same period by the same operator in another hospital. The methodology was the same in both groups. Success rates, complications, procedure time, radiofrequency time, total and operator fluoroscopy time, and recurrence rates were compared. RESULTS: There were no differences in success and complication rates. Procedure and total fluoroscopy times were not significantly different, but operator fluoroscopy time was significantly shorter with the magnetic navigation system (2.4±1.5 min vs. 7.2±4 min; p<0.001). The recurrence rate was higher in the manual group, although without statistical significance. CONCLUSIONS: The ablation of AVNRT with magnetic navigation is feasible using the same methodology as for manual ablation. Success and complication rates were similar. Operator fluoroscopy time was significantly less with the magnetic navigation system.

Premature ventricular contractions of the right ventricular outflow tract: Upward displacement of the ECG unmasks ST elevation in V1 associated with the presence of low voltage areas.

INTRODUCTION AND AIMS: Frequent premature ventricular contractions (PVCs) originating from the right ventricular outflow tract (RVOT) are usually considered a benign entity and the ECG is typically normal. The aim of this study was to assess whether upward displacement of the ECG to the second intercostal space (ICS) would reveal any abnormal pattern. METHODS: A total of 18 consecutive patients with apparently normal hearts were studied, mean age 44±16 years, 12 women, who underwent catheter ablation of the RVOT due to frequent PVCs. A 12-lead ECG was performed in the standard position and repeated in a higher position, at the level of the second ICS. Three-dimensional bipolar electroanatomical voltage mapping (EVM) was performed in all patients and low voltage areas (LVAs) were defined as areas with amplitude <1.5 mV. RESULTS: The ECG in the second ICS was normal in eleven patients but in seven (39%) it revealed a pattern of ST-segment elevation in V1. EVM revealed the presence of LVAs in six patients (33%) which included the earliest activation site (EAS) in five. The ST elevation was associated with the presence of LVAs (p<0.0001) and with the LVAs at the EAS (p=0.002). CONCLUSION: In this group of patients with apparently normal hearts and with frequent PVCs of the RVOT, upward displacement of the ECG revealed the presence of ST elevation in more than one third of patients, and the ST elevation was associated with the presence of LVAs in the RVOT.

Long-term prognosis of patients with Brugada syndrome and an implanted cardioverter-defibrillator.

INTRODUCTION: Risk stratification of Brugada syndrome (BrS) remains controversial and recommendations for an implantable cardioverter-defibrillator (ICD) are not well established. The objective of this study was to assess the long-term prognosis of BrS patients with an ICD. METHODS AND RESULTS: Of 55 consecutive patients with BrS assessed between April 2002 and October 2012, 36 (mean age 41.7 ± 13.8 years; 81.8% male) underwent ICD implantation. Nineteen (52.8%) were asymptomatic, 11 (30.6%) had previous history of syncope (arrhythmic cause suspected in eight) and six (16.7%) had aborted sudden cardiac death (SCD). Spontaneous type 1 electrocardiographic (ECG) pattern was present in 25 (69.4%) patients and electrophysiological study (EPS), performed in 26 (72.2%), was positive in 22 (84.6%). During a mean follow-up of 74 ± 40 months (>5 years in 72% of cases), seven (19.4%) patients had appropriate shocks (annual event rate 2.8%). These patients most frequently had aborted SCD (54.1% vs. 6.9%; p=0.008) and nonsustained ventricular tachycardia (57.1% vs. 10.3%; p=0.016) during follow-up. Spontaneous type 1 ECG pattern, syncope and positive EPS were not significantly associated with appropriate shocks. Multivariate analysis revealed that aborted SCD was an independent predictor of appropriate shocks (HR 8.07, 95% CI 1.58-41.2; p=0.012). ROC curve analysis demonstrated that aborted SCD had moderate discriminatory power to predict appropriate shocks (AUC 0.751), with sensitivity of 57% and specificity of 93%. In terms of ICD-related complications, eight (22.2%) patients had inappropriate shocks during the follow-up period, mainly due to sinus tachycardia (five patients); one patient had lead infection and another had a lead fracture. CONCLUSION: In this population of BrS patients with ICD, the long-term rate of appropriate shocks was 2.8%/year. Aborted SCD was associated with a higher risk of appropriate shocks, whereas syncope and spontaneous type I ECG pattern did not predict this event.

Prognostic Value of a Very Prolonged Asystole during Head-Up Tilt Test.

BACKGROUND: Clinical significance and prognosis of a cardioinhibitory response to head-up tilt (HUT) test with a very prolonged asystole (≥30 seconds) is poorly studied. Our aim was to evaluate the treatment (including pacemaker implantation) and prognosis (syncope recurrence, syncope-related trauma, and overall mortality) of patients with a very prolonged asystole on a HUT test. METHODS AND RESULTS: A retrospective study was conducted in two centers between January 2003 and December 2013 and included a total of 2,263 consecutive HUT tests (sensitized with isosorbide dinitrate) performed in 2,247 patients with syncope of unknown etiology. Cardioinhibitory response with asystole was observed in 149 (6.6%) of these tests (44.3% women, mean age 37 ± 18 years old, 16.1% in the nonpharmacological phase), with a median duration of asystole of 10 (6-19) seconds. Very prolonged asystole (≥30 seconds) was documented in 11 (0.5%) patients (45% women; mean age 40 ± 19 years; only one in the nonpharmacological phase, 9 minutes after HUT). The longest pause lasted 63 seconds. In all patients, avoidance of triggering factors and physical counterpressure maneuvers were recommended. Telephone follow-up was performed: in one patient, fludrocortisone was started; tilt training was conducted in one patient and none received a pacemaker. After a median follow-up of 42 (30-76) months, four patients (36%) had syncopal recurrences, one patient had a syncope-related injury (scalp laceration), and no patient died.

Remote magnetic navigation for ablation of typical atrial flutter: Long-term results.

INTRODUCTION AND AIM: Remote magnetic navigation has proved to be effective in the ablation of most supraventricular and ventricular arrhythmias. Initial studies reported worse results with this system compared to conventional ablation for atrial flutter. The aim of this study was to assess the acute and long-term success of atrial flutter ablation with remote magnetic navigation and to retrospectively compare the results obtained with an 8-mm tip catheter versus an irrigated catheter. METHODS: We studied 38 consecutive patients, mean age 61 ± 15 years, 28 male, who underwent ablation of typical atrial flutter with the Niobe II remote magnetic navigation system (Stereotaxis). Ablation was performed with an 8-mm tip catheter in 17 patients and with an irrigated-tip catheter in 21 patients. Acute success was defined as the presence of bidirectional isthmus block, and long-term success as absence of symptoms and atrial flutter during Holter monitoring. RESULTS: Bidirectional isthmus block was achieved in 37 patients (97%), and the success rate was similar in both groups. Total procedure time was not significantly different between the groups but fluoroscopy time was shorter in the irrigated tip group (13.4 ± 3.7 min vs. 6 ± 4.4 min; p<0.01). The number of applications and total radiofrequency time did not differ. There were no complications. During a follow-up of 32 ± 19 months there were two relapses, one in each group. CONCLUSIONS: The Niobe II remote control system for ablation of typical atrial flutter is safe and effective in both the short and long term. The 8-mm and irrigated-tip catheters showed similar safety and efficacy.

Percutaneous epicardial ablation in ventricular arrhythmias.

INTRODUCTION: Reentrant circuits of ventricular tachycardia may involve not only the endocardium but also the epicardium. Epicardial ablation can be useful in these situations. OBJECTIVE: The aim of this study was to assess efficacy, safety and complications in a series of consecutive patients who underwent ablation of ventricular tachycardia with epicardial mapping. METHODS: The study included all patients undergoing ventricular tachycardia ablation with epicardial mapping from 2004 to 2012. Of a total of 95 ablations, an epicardial approach was attempted in nine patients, eight male, mean age 58±12 years. Endocardial mapping was performed in all patients previously or simultaneously. The etiology of the arrhythmia was non-ischemic in eight patients and ischemic in one. We compared the number of events in the six months prior to the epicardial procedure and six months after. RESULTS: Percutaneous epicardial access was achieved in eight patients. In one case it was not possible due to the presence of adhesions. In none of the patients was the procedure repeated and there were no major complications during hospitalization. In a mean follow-up of 3.5±1.2 years, one patient suffered stroke; there were no other medium-to-long-term complications and the number of ventricular tachycardia episodes was reduced in all patients after ablation. CONCLUSIONS: Epicardial radiofrequency ablation of ventricular tachycardia was effective in reducing morbidity in eight patients, with a low risk of complications in the short and medium-to-long term.

Remote magnetic navigation for mapping and ablation of right and left ventricular outflow tract arrhythmias.

OBJECTIVE: The aim of this study was to assess the efficacy and potential complications of a remote-controlled magnetic navigation system (Niobe II, Stereotaxis) for mapping and ablation of right or left ventricular outflow tract ventricular tachycardia or premature ventricular contractions. METHODS: We studied 32 consecutive patients, mean age 43±11 years, 24 female. Mapping of the arrhythmia was performed using the CARTO RMT mapping system, remotely guided by the Niobe II. Radiofrequency ablation was performed at the site of earliest ventricular activation with pacemapping of at least 11/12 leads. Acute success was defined as suppression and non-inducibility of the arrhythmia after stimulation with isoprenaline. After a minimum 3-month follow-up, we assessed clinical success (absence of symptoms and suppression of the arrhythmia on Holter recording), defined as less than 50 premature ventricular contractions/24 hours. RESULTS: The origin of the arrhythmia was in the right ventricular outflow tract in 28 patients (88%), in the left in three, and in the epicardium in one. Acute success was achieved in 26 patients (81%). Two patients underwent a second successful procedure, in one of which an epicardial approach was necessary. The overall clinical success rate, after two repeat procedures, was 88%. No complications occurred. There were two recurrences during a mean follow-up of 307±204 days. CONCLUSION: The Niobe II remote control system for mapping and ablation of ventricular outflow tract arrhythmias is effective and safe, and provides precise mapping and a high success rate, with no complications.

Atrial fibrillation ablation: importance of cavotricuspid isthmus block.

INTRODUCTION AND OBJECTIVE: Maintenance of atrial fibrillation (AF) depends on the presence of multiple reentrant circuits in the atria. In AF ablation, after pulmonary vein (PV) isolation, substrate modification can be increased by performing linear lesions in the left atrium that reduce the fibrillatory surface. A cavotricuspid isthmus (CTI) block may be an easier and safer alternative to left atrial lines for this purpose. Non-inducibility after AF ablation is associated with a higher success rate. The aim of this study is to assess whether CTI ablation after PV isolation reduces inducibility of atrial arrhythmias, particularly AF. METHODS AND RESULTS: In 29 consecutive patients (23 male, mean age 54.6+/-11.4 years, 11 (38%) with hypertension and four (14%) with structural heart disease, mean left atrial dimension 43+/-6 mm) undergoing PV isolation for paroxysmal or persistent AF, atrial arrhythmia inducibility was tested before and after CTI ablation. The procedure was performed using a CARTO-Merge mapping system, one or two Lasso catheters, an irrigated ablation catheter and radiofrequency energy. Atrial arrhythmia inducibility was tested with burst pacing down to 150 ms or atrial refractoriness from the proximal coronary sinus. Atrial arrhythmias were considered inducible if they persisted for more than 60 seconds. Of the 29 patients, 26 (90%) had an inducible arrhythmia before CTI ablation--AF in 16, typical atrial flutter (AFL) in seven and atypical AFL in three. Three (10%) were non-inducible. After CTI ablation, only 11 patients (38%) maintained arrhythmia inducibility (p<0.001)--AF in nine and atypical AFL in two. There was a significant reduction of AF inducibility (16 vs. 9/29, p=0.016) and of combined AF and atypical AFL inducibility (19 vs. 11/29, p=0.021). After one year of follow-up, 23 patients (79%) had no recurrence of arrhythmia. Success rates were 83% in patients without and 73% in patients with inducible arrhythmias at the end of the procedure (p=NS). CONCLUSION: CTI ablation, in addition to PV isolation, significantly reduced the number of patients with inducible atrial arrhythmias and inducible AF.

Hybrid approach to severe coarctation and aortic regurgitation.

Aortic coarctation is occasionally detected only in adulthood, usually in the context of systemic hypertension. It is frequently associated with other malformations, but the presence of severe disease of the aortic or mitral valves is rare. Such associated lesions, nonetheless, have important implications regarding the type and timing of therapeutic interventions. We describe an adult patient with severe aortic coarctation, aortic valvar regurgitation, and impaired left ventricular systolic function. We treated the aortic coarctation first by means of percutaneous dilation and implantation of a stent. Four days later, we proceeded to treat the aortic regurgitation surgically, using the Bentall procedure. Our experience documents a safe and efficient therapeutic approach to this association of lesions.

Ventricular tachycardia ablation in patients with coronary heart disease: beyond the reentry circuit.

INTRODUCTION: Patients with coronary heart disease and left ventricular dysfunction are at increased risk for the development of ventricular tachycardia (VT) related to areas of myocardial fibrosis. Although the mechanism and the circuit of this arrhythmia are well understood, little is known about the triggers that precipitate VT episodes. Purkinje fiber potentials may be responsible for idiopathic VT, and recent studies have related them to polymorphic VT and ventricular fibrillation. METHODS: Between January 2002 and December 2003, we performed ablation in 10 patients with coronary heart disease, left ventricular systolic dysfunction and VT refractory to pharmacological therapy. All patients had implantable cardioverter-defibrillators. Electroanatomical activation and voltage mapping (CARTO) and electrophysiological criteria (premature activation during VT, pace mapping, and presence of diastolic potentials) were used to define scar regions, slow conduction areas and the reentry circuit isthmuses. RESULTS: Spike potentials were recorded in the scars of three patients. These potentials were almost fused with the ventricular electrogram during sinus rhythm, and were more premature during VT, probably reflecting local activation of Purkinje fibers. During ablation, we were able to dissociate the spike from the ventricular electrogram, thus terminating the VT. In the cases with conduction recovery, ventricular; ectopic beats recurred, preceded by a spike and degenerating into short runs of VT. The ablation strategy was not modified since persistence of the VT required the isthmus. CONCLUSION: The results suggest that residual Purkinje fibers may be present in scar regions and that the activity of these fibers may trigger VT in pre-established circuits.

Coronary sinus pacing in a patient with a tricuspid prosthesis.

We present images of a permanent pacing lead implanted in the coronary sinus of a patient with a tricuspid prosthesis.

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.

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.

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.

Influence of prior medication on mode of presentation and prognosis of acute coronary syndromes.

OBJECTIVES: To evaluate the influence of prior medication on mode of presentation and short-term prognosis of acute coronary syndromes (ACS). DESIGN: Prospective study. SETTING: Coronary intensive care unit in Santa Cruz Hospital. POPULATION: We included 425 consecutive patients admitted for ACS. METHODS: Prior medication with anti-platelet agents, beta-blockers, nitrates, calcium channel blockers, statins and angiotensin-converting enzyme (ACE) inhibitors was recorded on admission. Medication introduced in the last 7 days was excluded. Using a multivariate analysis model we examined the impact of baseline characteristics and previous medication on mode of presentation of ACS. We also evaluated their influence on short-term prognosis (death or non-fatal myocardial (re)infarction in the first 30 days). RESULTS: Of the 425 patients studied 228 (53.6%) presented with unstable angina (UA), the remainder with acute myocardial infarction (AMI) (24.7% with ST elevation). Medication prior to admission included anti-platelet agents in 53.7% of patients, beta-blockers in 44.2%, nitrates in 48.2%, calcium channel blockers in 36.9%, statins in 28.9% and ACE inhibitors in 38.6%. During the first 30 days, 14 deaths (3.3%) and 37 (re)infarctions (8.7%) occurred. The combined occurrence of death or (re)infarction was 10.8%. Variables with significant and independent influence on mode of presentation of ACS were male gender, presence of known coronary artery disease and previous medication with anti-platelet agents and beta-blockers. Male gender was a predictor of AMI as mode of presentation, whereas a previous history of coronary artery disease and medication with anti-platelet agents or beta-blockers predicted UA. Short-term prognosis was influenced by heart failure symptoms on admission, but not by previous medication. CONCLUSION: Previous medication with anti-platelet agents and beta-blockers was associated with an increased frequency of UA as mode of presentation of ACS. No relation between previous medication and short-term prognosis was observed in the present study.