Inducibility of atrioventricular nodal reentrant tachycardia and ectopic atrial tachycardia in children under general anesthesia.

BACKGROUND: In children, invasive electrophysiological studies (EPS) and radiofrequency catheter ablations (RFA) of supraventricular tachycardia (SVT) are often performed under general anesthesia. Atrioventricular nodal reentrant tachycardia (AVNRT) and ectopic atrial tachycardia (EAT) must be inducible during EPS as reliable diagnosis and subsequent therapy are not possible in sinus rhythm. This study aims to assess the problem of noninducible AVNRT and EAT under general anesthesia. METHODS AND RESULTS: Anesthesia protocols of 166 patients undergoing EPS were retrospectively analyzed. 122 AVNRT patients were compared to 22 whose tachycardia was not inducible but probably due to an AVNRT mechanism. Another 16 patients with inducible EAT were compared to 6 whose EAT appeared on surface ECG but not during EPS. Demographic characteristics were similar among all groups. Inducibility did not differ (p = .42) between AVNRT patients with inhalational anesthesia (sevoflurane and/or nitrous oxide) and patients with intravenous anesthesia (propofol with/without remifentanil). The EAT group exhibited lower inducibility under intravenous anesthesia (64%) than under inhalational (88%), however without significance (p = .35). CONCLUSION: Tachycardia induction succeeds with similar frequency under both inhalational and intravenous general anesthesia in children with AVNRT. In children with EAT, inhalational anesthesia is associated with a trend towards better inducibility.

Risk of Stroke in Patients With Short-Run Atrial Tachyarrhythmia.

BACKGROUND AND PURPOSE: The risk of stroke in patients with short-run atrial tachyarrhythmia (AT) remains unclear. This study aimed to investigate the relationship between short-run AT and the stroke and the use of the CHA2DS2-VASc score for the risk stratification. METHODS: From the registry of 24-hour Holter monitoring, 5342 subjects without known atrial fibrillation or stroke were enrolled. Short-run AT was defined as episodes of supraventricular ectopic beats <5 seconds. RESULTS: There were 1595 subjects (29.8%) with short-run AT. During the median follow-up period of 9.0 years, 494 subjects developed new-onset stroke. Patients with short-run AT had significantly higher stroke rates compared with patients without short-run AT (11.4% versus 8.3%; P<0.001). In patients with short-run AT, the number of strokes per 100 person-years for patients with CHA2DS2-VASc score of 0 and 1 were 0.23 and 0.67, respectively. However, the number of them for patients with CHA2DS2-VASc score of 2, 3, 4, and ≥5 were 1.62, 1.89, 1.30, and 2.91, respectively. In patients with CHA2DS2-VASc score of 0 or 1, age (>61 years old) and burden of premature atrial contractions (>25 beats/d) independently predicted the risk of stroke. In subgroup analyses, short-run AT patients were divided into 3 groups based on their CHA2DS2-VASc scores: low score (score of 0 [men] or 1 [women]; n=324), intermediate score (score of 1 [men] or 2 [women]; n=275), and high score (score of ≥2 [men] or ≥3 [women]; n=996). When compared with low score, intermediate and high scores were independent predictors for stroke (hazard ratio, 6.165; P<0.001 and hazard ratio, 8.577; P<0.001, respectively). CONCLUSIONS: Short-run AT increases the risk of stroke. Therefore, the CHA2DS2-VASc score could be used for the risk stratification. Age and burden of premature atrial contractions were independent predictors for stroke in patients with CHA2DS2-VASc score of 0 or 1.

Successful use of sirolimus for refractory atrial ectopic tachycardia in a child with cardiac rhabdomyoma.

Cardiac rhabdomyomas are common in tuberous sclerosis. We report a child who developed rhabdomyoma related arrhythmia refractory to antiarrhythmic drug therapy. Reversion of the atrial ectopic tachycardia was achieved with mammalian target of rapamycin pathway (mTOR) inhibitor sirolimus. As per our knowledge, this is the first time that sirolimus has been successfully used in this setting.

Predictors of Pharmacological Therapy of Ectopic Atrial Tachycardia in Children.

Ectopic atrial tachycardia (EAT) is a relatively common type of supraventricular tachycardia in the pediatric population, and it can be resistant to antiarrhythmic drugs and lead to tachycardia-induced cardiomyopathy (TIC) if not properly managed. The purpose of this study was to determine the predictors of the response to pharmacological therapy in children with EAT. From January 2009 to April 2014, 115 children were admitted to our hospital with a diagnosis of EAT and placed on antiarrhythmic drugs. We examined the clinical history, response to therapy, and follow-up of the children. The incidence of TIC secondary to EAT was 22.6% (n = 26) in children. Incessant EAT accounted for 44.3% of all patients. Control of EAT with antiarrhythmic therapy was achieved in 73.9% (n = 85) of the children. The combination of sotalol and propafenone performed well in controlling EAT in children [complete control in 35 (49.3%) of 71]. The mean time of conversion to sinus rhythm was 24 days, and the mean duration of therapy was 11 months in children with resolution. Multivariate predictors of the control of EAT were age at presentation (OR 0.289, P = 0.038) and tachycardia type (OR 0.276, P = 0.006). TIC occurs in 22.6% of children with EAT. Incessant EAT is more frequently complicated by TIC. Independent factors associated with a good response to pharmacological therapy include a younger age at presentation and non-incessant tachycardia in children with EAT.

Optimal noninvasive assessment of initial left ventricular dysfunction in children with ectopic atrial tachycardia.

UNLABELLED: Tissue Doppler imaging (TDI) can identify cardiac dysfunction in adults. This study is aimed to improve early identification of initial left ventricular (LV) dysfunction secondary to ectopic atrial tachycardia (EAT) in children by TDI. A total of 70 children with EAT were included in the present study. Cardiac function was evaluated by conventional echocardiography, TDI, and plasma N-terminal pro-brain natriuretic peptide (NT-proBNP). Doppler signals obtained from the mitral inflow and TDI of the mitral annulus were the average values of three consecutive heartbeats. Left ventricular ejection fraction (LVEF), peak early diastolic transmitral velocity (E), peak systolic mitral annulus velocity (S'), early diastolic mitral annular velocity (E'), the ratio E/E', and TDI-derived myocardial performance index (TDI-MPI) were compared between two groups of children with normal or elevated plasma NT-proBNP concentrations. Of the children, 18.6% demonstrated tachycardia-induced cardiomyopathy (TIC). Compared with LVEF, the TDI-MPI and E/E' showed better correlations with elevated plasma NT-proBNP. Addition of TDI-MPI and E/E' to LVEF provided increased information to detect elevated plasma NT-proBNP (91.67% sensitivity). CONCLUSIONS: TIC occurred in 18.6% of children with EAT. Initial LV dysfunction assessed by the TDI-MPI and E/E' is associated with elevated plasma NT-proBNP, even the LVEF is normal.

The presence of extensive atrial scars hinders the differential diagnosis of focal or macroreentrant atrial tachycardias in patients with complex congenital heart disease.

AIMS: Atrial tachycardias (ATs) frequently develop in patients with congenital heart defects (CHDs). This study aimed to evaluate the effects of extensive atrial scar formation on the total atrial activation time (TAAT) and its relation to the tachycardia cycle length (CL) to classify AT. METHODS AND RESULTS: Seventy-one patients were included and divided into two groups: patients without CHD (Group I, 35 patients) and with CHD (Group II, 36 patients). All patients underwent CARTO electroanatomical activation mapping. Two subgroups were created: centrifugal (CAT) or macroreentrant AT (MRAT). Total atrial activation time, CL, and mean bipolar signal amplitude (BiSA) were analysed. In Group I, 18 patients (51.4%) had CAT and 17 (48.6%) MRAT. The mean BiSA for Group I was 1.30 ± 0.32 mV. Total atrial activation time/CL ratios were different between CAT and MRAT (28.4 ± 16.9 vs. 66.6 ± 14.3%, P < 0.001). In Group II, 18 patients (50%) had CAT and 18 patients (50%) MRAT. The mean BiSA was 0.94 ± 0.50 mV and was not different for CAT and MRAT subgroups (1.04 ± 0.64 vs. 0.85 ± 0.29, P = 0.243). Total atrial activation time/CL ratios were comparable between CAT and MRAT patients (69.0 ± 40.4 vs. 83.6 ± 8.3%, P = 0.243). A significant lower BiSA was found for CAT with TAAT/CL ratios above 40% (0.62 ± 0.11 vs. 1.90 ± 0.18 mV, P < 0.001). A strong negative correlation was identified between the BiSA and the TAAT/CL ratio in patients with CAT in Group II (-0.742; P < 0.001). CONCLUSION: Low mean BiSA values in CHD patients are associated with altered impulse propagation, making TAAT- and CL-based diagnostic tools inaccurate. Further diagnostic tests are needed to determine the correct mechanism of ATs.

Ablation of atrial tachycardia and atrial flutter in heart failure.

Atrial tachycardia and atrial flutter are common tachyarrhythmias in the heart failure population. They commonly lead to, exacerbate, and increase the morbidity and mortality associated with heart failure and, thereby, warrant urgent and early definitive therapy in the form of catheter ablation. Catheter ablation requires careful patient stabilization and extensive preprocedural planning, particularly with regards to anesthesia, strategy, catheter choice, mapping system, and fluid balance, to increase efficacy and limit adverse effects. Heart failure may limit the success of catheter ablation with higher reported recurrence rates, and in selected patients, a hybrid epicardial-endocardial ablation can be considered.

Focal left atrial tachycardias not associated with prior catheter ablation for atrial fibrillation: clinical and electrophysiological characteristics.

BACKGROUND: The clinical features and electrophysiological characteristics of patients with focal left atrial tachycardias (LATs) are not well characterized. This study reports the experience of a single center in catheter mapping and radiofrequency ablation of focal LAT not associated with prior atrial fibrillation (AF) ablation, including in cardiac sarcoidosis and transplant patients. METHODS: Patients with focal LAT without a history of AF ablation were included in this retrospective analysis. RESULTS: A total of 24 focal LATs were documented in 20 patients. Two patients were subsequently diagnosed with cardiac sarcoidosis. Two patients were status post a thoracic transplant. The mean initial cycle length of the focal LATs was 347.4 ± 96.2 ms (range 190-510 ms). Patients with a pulmonary vein (PV) ostium focus (n = 6) demonstrated a shorter cycle length than patients with other LA foci (259.2 ± 56.4 ms vs 371.9 ± 91.1 ms, P = 0.02), as well as a trend for a history of AF (67% vs 21%, P = NS). Catheter ablation was immediately successful for 19 of 22 focal LATs. CONCLUSIONS: Focal LATs not associated with prior AF ablation can originate in a variety of LA locations and clinical settings. Focal LAT arising in the PV ostia is associated with a history of AF and demonstrates a faster tachycardia rate. We also report focal LAT in cardiac sarcoidosis patients and in the donor heart of an orthotopic heart transplant recipient. Radiofrequency ablation is a successful treatment for focal LAT not associated with prior ablation, including those refractory to medical therapy.

[Tachycardiomyopathy as a reversible cause of heart failure: report of one case]. / Taquicardiomiopatía, causa reversible de insuficiencia cardiaca: caso clínico.

Tachycardiomyopathy is a potentially reversible cause of heart failure. It can be induced by supraventricular or ventricular arrhythmias. When these are treated, systolic function improves or normalizes. We report a 20 year-old male with deterioration of left ventricular function and dilated cardiomyopathy secondary to an incessant atrial tachycardia that was treated with radiofrequency catheter ablation. After the procedure, the patient experienced a significant improvement of his ventricular function.

Coexistence of 2 types of atrial tachycardias and right ventricular outflow tract tachycardia.

Double tachycardia is a relatively uncommon type of tachycardia. In this report, we discuss a 68-year-old woman with history of frequent palpitations. Electrophysiologic study revealed that narrow QRS tachycardias from 2 origins and 1 wide QRS tachycardia were induced and each of the tachycardias was induced by the other. We found that 2 focal atrial tachycardias and 1 ventricular tachycardia originated from right ventricular outflow tract. All of these tachycardias were successfully ablated during one session, and no recurrence appeared during 10 months of follow-up.

Ectopic atrial tachycardia in an infant with transient erythroblastopenia of childhood.

Transient erythroblastopenia of childhood is a self-limited anemia occurring in previously healthy children, secondary to temporary cessation of erythrocyte production. Although the precise etiology is unclear, most cases are associated with a viral illness. The anemia may be severe, with associated pallor, tachypnea, and tachycardia; treatment is supportive. We present an unusual case of a child with viral-induced transient erythroblastopenia of childhood and associated ectopic atrial tachycardia, requiring therapy with antiarrhythmics.

Mapping and ablation of atypical AVNRT from the morphologic left atrium in a patient with dextrocardia and situs inversus.

A 75-year-old woman with dextrocardia, situs inversus, and subpulmonic outflow obstruction presented with recurrent supraventricular tachycardia (SVT). This SVT was easily inducible during electrophysiology study, and pacing maneuvers during SVT were consistent with atypical, slow-slow atrioventricular nodal reentrant tachycardia (AVNRT). The His bundle was identified in the low postero-septal morphologic right atrium, at the typical anatomic site for slow pathway ablation of AVNRT. Mapping of the retrograde earliest atrial electrogram during AVNRT localized this site to the mid-septal morphologic left atrium, and cryoablation at this site terminated the AVNRT and rendered it noninducible.

A rare complication of radiofrequency catheter ablation of left atrial tachycardia: atrial septal dissection and left atrial hematoma formation.

A 52-year-old man with left atrial tachycardia underwent radiofrequency catheter ablation. A steerable 4-mm-tip ablation catheter was advanced into the left atrium through a patent foramen ovale without transseptal puncture. However, the tip of the catheter was stuck in a structure. A pull-back maneuver rendered the catheter free and the procedure was cancelled. Transthoracic and transesophageal echocardiograms obtained immediately after the procedure showed intimal layer dissection in the interatrial septum and intramural hematoma formation throughout the anterior left atrial wall. The patient was in stable condition. Therefore, he was followed-up conservatively with serial echocardiographic examinations. The dissected intimal layer disappeared in 10 days and the hematoma underwent near-complete resolution in three months. This case highlights a rare complication of catheter ablation procedure that all interventionists should be familiar with.

Reversal of global apoptosis and regional stress kinase activation by cardiac resynchronization.

BACKGROUND: Cardiac dyssynchrony in the failing heart worsens global function and efficiency and generates regional loading disparities that may exacerbate stress-response molecular signaling and worsen cell survival. We hypothesized that cardiac resynchronization (CRT) from biventricular stimulation reverses such molecular abnormalities at the regional and global levels. METHODS AND RESULTS: Adult dogs (n=27) underwent left bundle-branch radiofrequency ablation, prolonging the QRS by 100%. Dogs were first subjected to 3 weeks of atrial tachypacing (200 bpm) to induce dyssynchronous heart failure (DHF) and then randomized to either 3 weeks of additional atrial tachypacing (DHF) or biventricular tachypacing (CRT). At 6 weeks, ejection fraction improved in CRT (2.8+/-1.8%) compared with DHF (-4.4+/-2.7; P=0.02 versus CRT) dogs, although both groups remained in failure with similarly elevated diastolic pressures and reduced dP/dtmax. In DHF, mitogen-activated kinase p38 and calcium-calmodulin-dependent kinase were disproportionally expressed/activated (50% to 150%), and tumor necrosis factor-alpha increased in the late-contracting (higher-stress) lateral versus septal wall. These disparities were absent with CRT. Apoptosis assessed by terminal deoxynucleotide transferase-mediated dUTP nick-end labeling staining, caspase-3 activity, and nuclear poly ADP-ribose polymerase cleavage was less in CRT than DHF hearts and was accompanied by increased Akt phosphorylation/activity. Bcl-2 and BAD protein diminished with DHF but were restored by CRT, accompanied by marked BAD phosphorylation, enhanced BAD-14-3-3 interaction, and reduced phosphatase PP1alpha, consistent with antiapoptotic effects. Other Akt-coupled modulators of apoptosis (FOXO-3alpha and GSK3beta) were more phosphorylated in DHF than CRT and thus less involved. CONCLUSIONS: CRT reverses regional and global molecular remodeling, generating more homogeneous activation of stress kinases and reducing apoptosis. Such changes are important benefits from CRT that likely improve cardiac performance and outcome.