Brugada Pattern Caused by a Flecainide Overdose.

BACKGROUND: Brugada pattern can be found on the electrocardiogram (ECG) of patients with altered mental status, usually with fever or drug intoxication. Diagnosis remains challenging, because the ECG changes are dynamic and variable. In addition, triggers are not always clearly identified. In patients with atrial fibrillation (AF), the use of class IC antidysrhythmic drugs can unmask a Brugada pattern on the ECG, especially if combined with other medications acting on sodium channels. CASE REPORT: A 62-year-old man with a medical history of AF was admitted to our emergency department for altered mental status. The ECG at the time of admission showed a Brugada pattern, triggered by a flecainide overdose (about 1 g), in association with an unknown dose of lamotrigine and quetiapine. After discontinuation of all medications, the Brugada pattern disappeared and his ECG showed no abnormalities. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: In patients with AF, the use of class IC antidysrhythmic drugs, if overdosed, can trigger a Brugada ECG pattern, and therefore it can increase the risk for malignant dysrhythmias. It is important to provide, to all patients with a Brugada ECG pattern, a list of drugs to avoid, and to underline the synergistic interplay between drugs, taking into consideration all patients' comorbidities.

Sharp Potential in Cavo-tricuspid Isthmus Targeted during Typical Atrial Flutter Radiofrequency Ablation.

The aim of this study was to define atrial electrograms (EGM) morphology, which could predict a conduction gap in cavo-tricuspid isthmus (CTI) during typical atrial flutter (AF) radiofrequency ablation. One hundred atrial EGM were retrospectively analysed. We demonstrated that recognising a sharp potential (short duration and high amplitude) is useful for quickly achieving CTI bi-directional block during typical AF ablation.

Noninvasive pacing study via pacemakers and implantable cardioverter-defibrillators for differentiating right from left atrial flutter.

BACKGROUND: Patients with atrial flutter who are implanted with a pacemaker (PM) or implantable cardioverter-defibrillator (ICD) present with the opportunity to perform a noninvasive pacing study (NIPS) using the right atrial pacing lead to differentiate right from left atrial flutter. OBJECTIVES: The purpose of this study was to study the feasibility and accuracy of NIPS to distinguish right from left atrial flutter. METHODS: We enrolled consecutive patients scheduled for an electrophysiological study or ablation procedure who were in atrial flutter and who were implanted with a PM or ICD with a functional atrial lead in the right atrial appendage. Flutter tachycardia cycle lengths (TCLs) and postpacing intervals (PPIs) were measured noninvasively via the device during the procedure. RESULTS: A total of 48 (67%) patients were studied. Right atrial flutter was present in 32 patients (of whom 29 had typical cavotricuspid isthmus-dependent flutter) and 16 (33%) patients had left atrial flutter. A PPI-TCL interval of >100 ms was 100% specific and 81% sensitive to identify left atrial flutter, with an overall accuracy of 94% and a c statistic of 0.94 (95% confidence interval 0.87-1.00). A PPI-TCL interval of ≤100 ms had a positive predictive value of 86% for diagnosing typical flutter. CONCLUSION: NIPS via PMs and ICDs with a PPI-TCL interval of >100 ms can reliably identify left atrial flutter (although we have only validated this cutoff for leads implanted in the right atrial appendage). This simple maneuver may allow planning for left-sided access and may avoid an unnecessary invasive electrophysiological study if left atrial flutter ablation is not to be considered.

Thromboembolic events 7-11 years after catheter ablation of atrial fibrillation.

BACKGROUND: The results of catheter ablation of atrial fibrillation (AF) beyond 6 years remain unknown. The goal of this study is to assess the risk of thromboembolic events (TEs) and outcomes of AF ablation at long-term follow-up (FU). METHODS: All patients who had AF ablation from 2002 until 2005 in our center were contacted for a FU including a questionnaire, cardiac rhythm monitoring, and transthoracic echocardiography. RESULTS: Among the 264 eligible patients, 164 (62%) completed the study. The mean FU was 9.1 years (7.7-10.5). Seven patients had a TE during FU (event ratio 0.41 per 100 patient years [PY]) and their mean CHA2DS2-VASc score was 3.1 ± 1.3. Two patients died from stroke (0.14 per 100 PY) and five of the seven were considered in sinus rhythm (SR) and were off anticoagulation at the time of event. Prior to ablation, 13 patients had history of TE, and only one had a TE during FU. Overall, 14 deaths were documented (0.58 per 100 PY). Stable SR was present in 111 patients (68% of 164 patients) after 1.5 ± 0.6 procedures/patient. Univariate analysis showed that dyslipidemia (odds ratio [OR] = 2.95, P = 0.003), CHA2DS2-VASc ≥2 (OR = 3.22, P = 0.001), and amiodarone (OR = 5.64, P < 0.001) were predictors of long-term recurrence. Multivariate analysis showed that only CHA2DS2-VASc ≥2 (OR = 2.67, P = 0.023) and amiodarone (OR = 4.62, P = 0.001) were predictors. CONCLUSIONS: Our study shows low TE rates 9 years after ablation of AF that are lower than published data for AF patients with anticoagulation only. AF patients with a CHA2DS2-VASc ≥2 should, however, be maintained on anticoagulation.

Reversible ventricular arrythmia induced by dasatinib.

KEY CLINICAL MESSAGE: Ventricular arrhythmias induced by dasatinib are rare events, but physicians in charge of chronic myeloid leukemia patients should be aware of such potential complications and the need for regular ECG controls during treatment with tyrosine kinase inhibitors.

Pacing of the interventricular septum versus the right ventricular apex: a prospective, randomized study.

BACKGROUND: Left ventricular (LV) function may be impaired by right ventricular (RV) apical pacing. The interventricular septum is an alternative pacing site, but randomized data are limited. Our aim was to compare ejection fraction (EF) resulting from pacing the interventricular septum versus the RV apex. METHODS: RV lead implantation was randomized to the apex or the mid-septum. LVEF and RVEF were determined at baseline and after 1 and 4 years by radionuclide angiography. RESULTS: We enrolled 59 patients, of whom 28 were randomized to the apical group and 31 to the septal group, with follow-up available in 47 patients at 1 year and 33 patients at 4 years. LVEF in the apical and in the septal groups was 55 ± 8% vs. 46 ± 15% (p=0.021) at 1 year and 53 ± 12% vs. 47 ± 15% (p=0.20) at 4 years. Echocardiography confirmed a mid-septal lead position in only 54% of patients in the septal group, with an anterior position in the remaining patients. In the septal group, LVEF decreased significantly in patients with an anterior RV lead (-10.0 ± 7.7%, p=0.003 at 1 year and -8.0 ± 9.5%, p=0.035 at 4 years), but not in patients who had a mid-septal lead. Left intraventricular dyssynchrony was significantly increased in case of an anterior RV lead. RVEF was not significantly impaired by RV pacing, regardless of RV lead position. CONCLUSIONS: Pacing at the RV septum confers no advantage in terms of ventricular function compared to the apex. Furthermore, inadvertent placement of the RV lead in an anterior position instead of the mid-septum results in reduced LV function.

QRS pattern and improvement in right and left ventricular function after cardiac resynchronization therapy: a radionuclide study.

BACKGROUND: Predicting response to cardiac resynchronization therapy (CRT) remains a challenge. We evaluated the role of baseline QRS pattern to predict response in terms of improvement in biventricular ejection fraction (EF). METHODS: Consecutive patients (pts) undergoing CRT implantation underwent radionuclide angiography at baseline and at mid-term follow-up. The relationship between baseline QRS pattern and mechanical dyssynchrony using phase analysis was evaluated. Changes in left and right ventricular EF (LVEF and RVEF) were analyzed with regard to baseline QRS pattern. RESULTS: We enrolled 56 pts, 32 with left bundle branch block (LBBB), 4 with right bundle branch block (RBBB) and 20 with non-specific intraventricular conduction disturbance (IVCD). A total of 48 pts completed follow-up. LBBB pts had significantly greater improvement in LVEF compared to RBBB or non-specific IVCD pts (+9.6 ± 10.9% vs. +2.6 ± 7.6%, p = 0.003). Response (defined as ≥ 5% increase in LVEF) was observed in 68% of LBBB vs. 24% of non-specific IVCD pts (p = 0.006). None of the RBBB pts were responders. RVEF was significantly improved in LBBB (+5.0 ± 9.0%, p = 0.007), but not in non-specific IVCD and RBBB pts (+0.4 ± 5.8%, p = 0.76). At multivariate analysis, LBBB was the only predictor of LVEF response (OR, 7.45; 95% CI 1.80-30.94; p = 0.006), but not QRS duration or extent of mechanical dyssynchrony. CONCLUSIONS: Presence of a LBBB is a marker of a positive response to CRT in terms of biventricular improvement. Pts with non-LBBB pattern show significantly less benefit from CRT than those with LBBB.

Comparison of tools and techniques for implanting pacemaker leads on the ventricular mid-septum.

INTRODUCTION: Many physicians target the interventricular septum for pacemaker implantation, but the lead may inadvertently end up in an anterior position. AIMS: We sought to compare two stylet shapes to achieve mid-septal lead placement, as well as the utility of a novel right anterior oblique (RAO) fluoroscopic landmark. METHODS AND RESULTS: Patients undergoing pacemaker implantation were enrolled into four consecutive groups according to stylet shape: a standard curve [two-dimensional (2D) stylet] or with an additional distal posterior curve [three-dimensional (3D) stylet], and whether RAO fluoroscopy was used. Left oblique anterior (LAO) and postero-anterior (PA) fluoroscopic views were used in all cases. After implantation, validation of right ventricular lead position (septal vs. anterior) was performed by echocardiography. A total of 113 patients were included, of whom lead position could be validated in 106 patients. Septal position was achieved in only 10 of 22 (45%) patients in the 2D stylet group and in 17 of 23 (74%) patients in the 3D stylet group (P = 0.07) when only PA and LAO fluoroscopy were used. Results were significantly improved by additional use of RAO fluoroscopy, with successful septal placement in 25 of 28 (89%) patients in the 2D stylet + RAO group (P = 0.001) and 32 of 33 (97%) patients in the 3D stylet + RAO group (P = 0.015). CONCLUSIONS: A septal lead position was obtained in only about half of the patients when a 2D stylet was used with only LAO and PA fluoroscopic views. A 3D stylet was useful to attain the target position, and additional RAO fluoroscopy significantly improved success rate with both stylet shapes.

Biatrial pacing improves atrial haemodynamics and atrioventricular timing compared with pacing from the right atrial appendage.

AIMS: Patients with interatrial conduction delay may have suboptimal left atrioventricular (AV) timing due to delayed contraction of the left atrium with foreshortening of ventricular filling. This may be an issue in pacemaker patients, especially those requiring resychronization therapy. Pacing from the high interatrial septum (IAS) or the distal or proximal coronary sinus (CSD and CSP) may improve left AV synchrony compared with pacing from the right atrial appendage (RAA). Our aim was to compare haemodynamics of these pacing sites. METHODS AND RESULTS: A total of 24 patients undergoing radiofrequency ablation for paroxysmal atrial fibrillation were studied. Left atrial pressures were recorded in sinus rhythm, and during pacing from the RAA, IAS, CSD, CSP, and with biatrial (BiA) pacing from the IAS + CSD. Amplitudes, +dP/dT(max), and timing of the a-wave were compared between recordings. Left atrial contractility, measured by +dP/dT(max), was greatest during BiA pacing (P ≤ 0.03 for all comparisons). There was a marked reduction in delay to peak a-wave when pacing from all sites compared with the RAA, with BiA pacing yielding the shortest delay (P ≤ 0.001). However, AV conduction was shortened by all alternative pacing sites, which mitigated the anticipation of left atrial contraction with respect to ventricular activation, except for BiA pacing (P < 0.001). Pacing of the IAS did not result in any improvement in haemodynamics or AV synchrony. CONCLUSION: Multisite atrial pacing results in favourable acute atrial haemodynamics and left AV synchrony. This may be a solution in pacemaker patients with interatrial conduction delay.

Utility of the surface electrocardiogram for confirming right ventricular septal pacing: validation using electroanatomical mapping.

AIMS: When targeting the interventricular septum during pacemaker implantation, the lead may inadvertently be positioned on the anterior wall due to imprecise fluoroscopic landmarks. Surface electrocardiogram (ECG) criteria of the paced QRS complex (e.g. negativity in lead I) have been proposed to confirm a septal position, but these criteria have not been properly validated. Our aim was to investigate whether the paced QRS complex may be used to confirm septal lead position. METHODS: Anatomical reconstruction of the right ventricle was performed using a NavX® system in 31 patients (70 ± 11 years, 26 males) to validate pacing sites. Surface 12-lead ECGs were analysed by digital callipers and compared while pacing from a para-Hissian position, from the mid-septum, and from the anterior free wall. RESULTS: Duration of the QRS complex was not significantly shorter when pacing from the mid-septum compared with the other sites. QRS axis was significantly less vertical during mid-septal pacing (18 ± 51°) compared with para-Hissian (38 ± 37°, P = 0.028) and anterior (53 ± 55°, P = 0.003) pacing, and QRS transition was intermediate (4.8 ± 1.3 vs. 3.8 ± 1.3, P < 0.001, and vs. 5.4 ± 0.9, P = 0.045, respectively), although no cut-offs could reliably distinguish sites. A negative QRS or the presence of a q-wave in lead I tended to be more frequent with anterior than with mid-septal pacing (9/31 vs. 3/31, P = 0.2 and 8/31 vs. 1/31, P = 1.0, respectively). CONCLUSION: No single ECG criterion could reliably distinguish pacing the mid-septum from the anterior wall. In particular, a negative QRS complex in lead I is an inaccurate criterion for validating septal pacing.

Right ventricular systolic function and cardiac resynchronization therapy.

AIMS: The effect of cardiac resynchronization therapy (CRT) on right ventricular ejection fraction (RVEF) has not been well studied. Furthermore, it is unclear whether baseline RVEF influences response to CRT. To evaluate the acute and chronic effects of CRT on right ventricular systolic function, and to investigate whether baseline RVEF impacts response to CRT. METHODS AND RESULTS: Forty-four patients with a standard indication for CRT underwent radionuclide angiography at baseline and after at least 6 months' follow-up for measuring RVEF, right ventricular synchrony (using phase analysis), and left ventricular ejection fraction (LVEF). In addition, NYHA functional class and 6-min walking distance (6MWD) were evaluated. There were no significant acute changes in RVEF with CRT. After a mean follow-up of 9 +/- 5 months, RVEF was slightly improved (by 1.9 +/- 5.0% in absolute terms, P = 0.016), and to a lesser extent than LVEF (5.1 +/- 9.0%, P = 0.009 compared with RVEF). Right ventricular dyssynchrony was significantly improved at follow-up (P = 0.016). Patients with a baseline RVEF < or = 0.35 (n = 19) were less likely to improve in NYHA class (P = 0.016), and also tended to improve less in 6MWD and LVEF (P < 0.06). CONCLUSION: Cardiac resynchronization therapy has no acute effect on RVEF, and only slightly improves RVEF at follow-up. Patients with reduced RVEF at baseline were less likely to respond to CRT, indicating that right ventricular systolic dysfunction may play a role in patient selection.

Backup right ventricular pacing with a 0.035'' guidewire during implantation of left ventricular leads.

INTRODUCTION: During implantation of biventricular devices, manipulation of the guiding sheath during localization of the coronary sinus (CS) ostium may result in injury to the right bundle and complete heart block. A preventive measure is to implant the right ventricular (RV) lead first, though this may interfere with manipulation of the guiding sheath and dislodge the permanent lead. We tested the feasibility of backup pacing with a 0.035'' guidewire, advanced through the guiding sheath during CS localization. METHODS: One hundred six consecutive patients (mean age = 70 +/- 11 years, 81 men) undergoing biventricular device implantation were studied. A 0.035'' guidewire with an uncoated tip was advanced into the right ventricle through the guiding sheath, and unipolar capture threshold, R-wave sensing amplitude, and pacing impedance were measured. RESULTS: RV pacing was successful in all patients. The mean capture threshold was 3.8 +/- 2.1 V/0.5 ms, R-wave amplitude 5.4 +/- 4.3 mV, and pacing impedance 226 +/- 78 Omega. No arrhythmia was observed during the tests. Two patients developed complete heart block during the implant procedure and were successfully paced temporarily using the 0.035'' guidewire. CONCLUSION: Temporary RV pacing, using a 0.035'' guidewire within the guiding sheath, is a simple, reliable, and safe method that allows backup pacing in case of traumatic complete heart block, developing during the implantation of biventricular devices.

Is this atrial fibrillation?

A 19-year-old girl was referred to our cardiology department for catheter ablation (isolation of the pulmonary veins) of paroxysmal atrial fibrillation (AF). The diagnosis was made upon a 12-lead ECG of the arrhythmia documented in the emergency room. The ECG showed an irregular tachycardia without wide QRS complexes. Careful assessment revealed the irregularity of the rhythm was a sweep artifact due to a mechanic failure of the ECG-machine to advance the article smoothly. During EP study a concealed anteroseptal accessory pathway causing an orthodromic AV reentrant tachycardia was eliminated by radio-frequency ablation. This example emphasizes the need for careful assessment of an ECG tracing, including printed legends and technical data.

Improvement in cardiac sympathetic nerve activity in responders to resynchronization therapy.

AIMS: To assess changes in cardiac adrenergic activity with cardiac resynchronization therapy (CRT), and to investigate whether these changes are related to improvement in left ventricular ejection fraction (LVEF). METHODS AND RESULTS: Sixteen patients (13 males, age 66 +/- 7 years) were studied at baseline and after > or =6 months of CRT (mean follow-up 9.2 +/- 3.2 months). LVEF was assessed by nuclear angiography. Responders were defined as patients showing > or =5% absolute increase in LVEF + improvement in > or =1 NYHA class + absence of heart failure hospitalization. Cardiac sympathetic nerve activity was studied by (123)I-metaiodobenzyl-guanidine ((123)I-MIBG) scintigraphy. Responders (n = 8) showed lower (123)I-MIBG washout at follow-up when compared with non-responders (P = 0.002), indicating lower cardiac sympathetic nerve activity. The decrease in (123)I-MIBG washout at follow-up when compared with baseline was only seen in the responder group (P = 0.036). There was a moderate correlation between increase in LVEF and decrease in (123)I-MIBG washout (r = 0.52, P = 0.04). CONCLUSION: CRT induces a reduction in cardiac sympathetic nerve activity in responders, that parallels an improvement in LVEF, whereas non-responders do not show any significant changes.

Cardiac transplantation in a patient with emotionally triggered implantable cardioverter defibrillator storms.

The implantable cardioverter defibrillator (ICD) may be responsible for psychological disorders especially among patients experiencing multiple shocks. An associated hyperadrenergic state (e.g., anger, anxiety) may trigger malignant ventricular arrhythmias repeatedly treated by ICD shocks, entertaining a "vicious circle" often difficult to interrupt. Despite aggressive cardiac and psychological therapeutic efforts, this condition may be refractory, finally leading to heart transplantation, as described in this case report.