Regular Tachycardia Research Articles

Clinical assessment and comparison of annotation algorithms in high‐density mapping of regular atrial tachycardias

High-density automated mapping of regular atrial tachycardias (ATs) requires accurate assessment of local activation times (LATs). To evaluate high-density mapping of ATs and compare the accuracy of different automated LAT annotation algorithms. Fifteen patients underwent AT ablation guided by the automated ConfiDENSEۛ high-density mapping module (Carto 3 v4) allowing manual reannotation (edited maps). For each AT, unedited automated maps were reconstructed offline by three algorithms: maximum unipolar slope (LATSlope ), bipolar peak (LATPeak ), and a new hybrid annotation algorithm (LATHybrid ). Five blinded experts were asked to define the (1) tachycardia mechanism, (2) ablation target, and (3) level of difficulty of these unedited maps. Twenty-one ATs (cycle length 300 ± 46ms, activation points 955 ± 421) were successfully ablated using LATHybrid guided ablation with manual editing in a small number of points. At 6 months, 14 (93%) of the patients were free of AT recurrences. Unedited LATHybrid maps showed the highest accuracy in defining the tachycardia mechanism (LATHybrid : 49%vs. LATPeak : 27%vs. LATSlope : 28%, P<0.001) and ablation target (LATHybrid : 65%vs. LATPeak : 39%vs. LATSlope : 31%, P<0.001). Overall, LATHybrid -annotated maps were graded as "easier to interpret" by the experts (difficulty score 2.3 ± 0.9) versus LATPeak (2.8 ± 1) and LATSlope (3.2 ± 0.8) (P<0.001). Only 12% of the LATHybrid maps were annotated as uninterpretable compared to 31% of LATSlope and 45% of the LATPeak maps (P<0.001). Automated LATHybrid annotation allows better and easier recognition of the tachycardia mechanism compared to automated LATPeak and LATSlope algorithms, although fully automated mapping still requires further improvements.

Contemporary Diagnosis and Management of Atrial Flutter: A Continuum of Atrial Fibrillation and Vice Versa?

Atrial flutter (AFlu) is usually a fast (>240 bpm) and regular right atrial macroreentrant tachycardia, with a constrained critical region of the reentry circuit located at the cavotricuspid isthmus (CTI; typical CTI-dependent AFlu). However, a variety of right and left atrial tachycardias, resulting from different mechanisms, can also present as AFlu (atypical non-CTI-dependent AFlu). The electrocardiogram can provide clues to its origin and location; however, additional entrainment and more sophisticated electroanatomical mapping techniques may be required to identify its mechanism, location, and target area for a successful ablation. Although atrial fibrillation and AFlu are 2 separate arrhythmias, they often coexist before and after drug and/or ablation therapies. Indeed, there appears to be a close interrelationship between these 2 arrhythmias, and one may "transform" into the other. These issues are discussed in this overview, and practical algorithms are proposed to guide AFlu localization and illustrate the AFlu and atrial fibrillation continuum.

Regular tachycardia despite Wenckebach atrioventricular conduction

We present a 21-year-old woman status post orthotopic heart transplantation initially presenting with a regular narrow complex tachycardia at 159beats/min. With intravenous diltiazem the rhythm transitioned to a regular tachycardia at 106beats/min, 2/3rd of the initial heart rate. We demonstrate this to be a novel description of 3:2second-degree Mobitz type I atrioventricular block (Wenckebach) with the absence of the hallmark regularly irregular (grouped beating) pattern.

PP.29.17] HYPERTENSIVE ENCEPHALOPATHY IN A TERIFLUNOMIDE TREATED PATIENT

Objective: One of the challenges of the last years is to take care of patients with complex treatments, including new drugs. Teriflunomide is a pyrimidine synthesis inhibitor, for the tratament of multiple sclerosis. Hypertension is, according to clinical trials, a rare adverse reaction- 4% for the 14 mg/day. Design and method: Case report: We present the case of a 56 years old women with multiple sclerosis- who begun a treatment with teriflunomide (14 mg/day). She was known as having a grade 2 HTA, obesity and hypercholesterolemia and her treatment consisted in telmisartanum, indapamide and atorvastatine. With this treatment the blood pressure was under 130/ 85 mmHg and she was considered with controlled hypertension when the new drug was introduced. After the second dose- the patient experienced, during nighttime, headache and in the third day of treatment she developed a severe headache, with photophobia and vomitig, and in the Emergency Room the blood pressure was 260/130 mmHg. The rest of clinical examination showed: normal pulmonary auscultation and no signs of systemic congestion, a regular cardiac rhytm and tachycardia (120 beats/min), no focal neurological signs or meningeal irritation. She was admitted to the hospital as hypertensive encefalopathy. The blood tests were normal, excepting a total cholesterol above the recommended limits; the ECG- without changes and an echocardiogram - no signs of left ventricular hypertrophy, a normal kinetic and valves, with a mild dyastolic dysfunction. Results: Under treatment with i.v. vasodilatators and supplementation of the oral treatment with a calcium blocker, the patient become asymptomatic and the blood pressure values return to the recommended limits. She was discharged with a new treatment scheme (adding amlodipine 5 mg/day to the previous drugs), and the ambulatory blood pressure measurement, performed 14 days after that, showed a good control of hypertension. Conclusions: New therapies come with new adverse reactions and in everyday patients, which are rather complex, the close followup is mandatory. The useful tratment for Multiple Sclerosis was, in this patient, followed by a rise of the antihypertensive treatment.

Taquicardias supraventriculares

IntroductionSupraventricular tachycardias include a set of arrhythmias with similar clinical and electrocardiographic presentation. DiagnosisWe should suspect a supraventricular tachycardia in patients typically without structural heart disease, in which episodes of regular palpitations of sudden onset and onset appear, varying in duration between minutes and up to hours, and in which, on the ECG performed during tachycardia, Observes a regular tachycardia of narrow QRS complex. In the differential diagnosis, three entities should be considered: intranodal tachycardia, accessory-mediated tachycardia and atrial tachycardia. ManagementThe invasive electrophysiological study gives the definitive diagnosis of the mechanism of tachycardia that, however, may be previously suspected based on electrocardiographic criteria during tachycardia or sinus rhythm and by the characteristics of the patient. Medical treatment is generally ineffective in this type of tachycardia, with ablation being an effective treatment in most cases and with a low risk profile.

P827Zero-fluoroscopy approach as the gold standard for catheter ablation of regular supraventricular tachycardias - experience beyond 1500 procedures

P827Zero-fluoroscopy approach as the gold standard for catheter ablation of regular supraventricular tachycardias - experience beyond 1500 procedures

Arrhythmia recurrence in patients following cardiac surgery with concomitant therapy of atrial fibrillation – Experience of our cardiac center

IntroductionSurgical treatment of atrial fibrillation (AF) is a common and time-proven treatment method for this type of arrhythmias both as a separate procedure and as a procedure related to cardiac surgery for another indication (concomitant procedure). Patients experience arrhythmia recurrence despite highly efficient surgical treatment. These arrhythmias are often resistant to pharmacological treatment (due to an extensive fibrous substrate); therefore, electroanatomical mapping accompanying catheter ablation is significantly more effective. The arrhythmogenic fibrous substrate is a result of both a primary cardiac disease (an underlying disease causing atrial dilation) and surgical intervention (incision, cannula insertion sites, MAZE lines with a renewed spread of electrical signal in these blocks). Method and patientsElectroanatomical mapping and ablation were performed in 92 patients with arrhythmia recurrence following concomitant surgical treatment for AF between January 2010 and November 2015. The Cox maze procedure was performed using a disposable cryoablation catheter. The heart rhythm in patients following radiofrequency ablation procedure was monitored in half-year intervals (24-h Holter ECG, 7-day loop recorder, in some patients also by means of implanted pacemakers or implantable loop recorders). The average left atrial size (PLAX) was 50mm, 59% of patients underwent mitral valve surgery, 54% of patients had tricuspid valve surgery, 16% were operated for congenital developmental disorders, in 17% of patients, repeated cardiac surgery was performed. The above-mentioned facts show that these are patients with an extensive arrhythmogenic substrate. ResultsThe Cox maze procedure resulted in an extensive fibrous arrhythmogenic substrate in the atrium (arrhythmia recurrence following the maze procedure is more often regular atrial tachycardias while AF is predominant among arrhythmias for which the maze procedure was indicated). All patients had a follow-up visit after 12 months, 80% of patients presented for a follow-up visit after 24 months. Early recurrence after ablation (within 3 months following the procedure) was found in 21% of patients. Early recurrence after ablation was statistically significantly related to arrhythmia recurrence within 12 months (p=0.003) and arrhythmia recurrence within 24 months (p=0.003). 73% of patients had no recurrent AF or atrial tachycardia (AT) after 12 months and 53% after 24 months. A total of 146 arrhythmias were ablated, i.e. 1/3 of patients had more than 1 arrhythmia. These were persistent AF found in 24% of patients, paroxysmal AF seen in 13% of patients and regular AT detected in 53% of patients. More than one half of regular AT originated in LA (as perimitral atrial flutter in most cases). Remaining arrhythmias originated from the right atrium (as typical atrial flutter in half of the cases). 57% of patients had a renewed spread of signal in the mitral isthmus (ablation of the coronary sinus was necessary in 1/3 of patients). No domination in the number of reconnections was found for any of the pulmonary veins. The finding of a significantly reduced signal amplitude in the entire LA was associated with a higher risk of acute ablation failure (p=0.001). Acute ablation failure was associated with a higher risk of arrhythmia recurrence after 12 months (p=0.07). There was a trend of a higher AT incidence originating from the RA in patients who underwent surgery for a congenital heart defect (p=0.06). The diagnosis of arterial hypertension was associated with a higher risk of arrhythmia recurrence (p=0.13). The finding of persistent AF on ECG (compared to other findings, i.e. paroxysmal AF and regular AT) before ablation did not increase the risk of recurrence after ablation. ConclusionIn patients after cardiac surgery, catheterization performed to treat arrhythmia recurrence is a effective method of subsequent treatment, despite an extensive arrhythmogenic substrate. A rather large number of AT cases originate from the right atrium, in particular in patients after surgery for congenital heart defects. Patients with a significantly reduced signal in the larger part of the atrium due to an extensive arrhythmogenic substrate present the most complicated cases.

P301Comparison of local activation time annotation algorithms in high density mapping of regular atrial tachycardias

P301Comparison of local activation time annotation algorithms in high density mapping of regular atrial tachycardias

Diagnosis and management of a wide QRS regular tachycardia

In spite of the available clinical and electrocardiographic criteria for the differential diagnosis of wide QRS complex tachycardias, distinguishing orthodromic supraventricular tachycardias is still a challenge. We present a case of a 63-year old patient admitted in our clinic after experiencing two episodes of syncope. Echocardiography showed left ventricular hypertrophy, grade 1 diastolic dysfunction and left atrial enlargement. A Holter monitoring revealed episodes of atrial fibrillation and paroxysmal narrow QRS tachycardia alternating with wide QRS tachycardia (170-180 bpm). During an electrophysiology study we induced self-limiting orthodromic supraventricular tachycardias with narrow and left bundle branch block patterns. Retrograde mapping near the mitral annulus identified a concealed accessory posteroseptal by-pass tract which was successfully ablated. After the procedure the patient developed atrial flutter and atrial fibrillation with rapid ventricular response (196 beats per minute) with a 3.9 s post-tachycardia pause. The patient underwent implantation of a cardiac pacemaker which allowed us to start antiarrhythmic treatment with amiodarone. This case shows that occult accessory posteroseptal by-pass tracts can have a late-onset presentation in a 63-year old male and explains why latent rhythm disturbances require a step-by-step medical approach.

Radiofrequency Ablation of Focal Atrial Tachycardia from Coronary Sinus

Focal atrial tachycardia (AT) is defined as atrial activation originating from a discrete focus with centrifugal spread. Available information suggests that focal activity can be caused by automaticity, triggered activity, or microreentry. Generally, AT response poorly to medication but can be treated by radiofrequency ablation with high long-term success. Focal AT represents approximately 3% to 17% of the patients referred for supraventricular tachycardia (SVT) radiofrequency ablation (RFA). Electrophysiology study is important to correctly diagnose the mechanism of the SVT before RFA is performed. Observation and several pacing maneuver could be done to identify the mechanism of SVT.A 54 year old female came with chief complaint of palpitation. During palpitation her ECG showed narrow complex regular tachycardia with the P-wave that was difficult to ascertain clearly. Electrophysiology study showed VA interval 130 ms, differences between VA interval during tachycardia and VA interval during RV pacing was 55 ms, no advanced in atrial activation, difference between ventricular post pacing interval (PPI) and tachycardia cycle length (TCL) was 130 ms, ventricular pacing during tachycardia results in V-A-A-V response before tachycardia resumes, and showed concentric atrial activation with earliest point at CS 9-10, indicating an AT from coronary sinus origin. AT was terminated during the RFA.Electrophysiology study is important to correctly diagnose AT, especially when P-wave during tachycardia in the surface ECG is uncertain. Several pacing maneuver during electrophysiology study can be very helpful to verify the diagnosis of AT.

Persistent tachycardia within isolated pulmonary veins during atrial fibrillation ablation.

During circumferential pulmonary vein (PV) isolation for ongoing atrial fibrillation (AF), distinguishing passive conduction to the pulmonary vein (PV) from rapid PV arrhythmia in the isolated PV is difficult. Hence, the purpose of this study is to investigate both the feasibility of distinguishing the PV tachycardia after circumferential PV isolation and the electrophysiological characteristics of these tachycardia. Among 178 consecutive patients who underwent circumferential PV isolation during ongoing AF, fibrillatory PV converted to a regular cycle length PV tachycardia independent of the atrial rhythm (=independent PV tachycardia) in 13 PVs among 12 (7%) patients. We classified independent PV tachycardia according to 3 different atrial rhythms: sinus rhythm (type 1, n = 2), atrial tachycardia (type 2, n = 4), and AF (type 3, n = 6). independent PV tachycardia was observed in 3 right PV and 10 left PV (P = 0.0864). There were 10 mappable independent PV tachycardia, in which 8 were focal and 2 were macroreentrant tachycardia. i-PVT can be diagnosed in a small number of patients who underwent circumferential PV isolation during AF. The main mechanism or independent PV tachycardia was focal tachycardia mainly in the left PV.

Nadolol for Treatment of Supraventricular Tachycardia in Infants and Young Children.

Supraventricular tachycardia (SVT) is a common infant arrhythmia, for which beta-blockers are frequently chosen as therapy. Propranolol is a common choice though it is dosed every 6-8h. We reviewed the clinical results of treating infant SVT with an extemporaneous preparation of nadolol. Retrospective cohort study of patients under 2years old receiving nadolol for SVT at a single center. Patients were ascertained by patient and pharmacy databases. Twenty-eight infants received nadolol, of whom 25 had regular narrow complex tachycardia, 2 atrial flutter, and 1 focal atrial tachycardia. Patient age at initiation was a median 54days (range 10-720). The final dose was 1mg/kg/day in 22/28 patients (range 0.5-2). Once-daily dosing was used in 20 patients (71.4%); dosing was BID in 7, TID in 1. Among regular narrow complex tachycardia patients, 18/25 received nadolol monotherapy and 7 required additional agents; flecainide in 6, digoxin in 1. The median age of tachyarrhythmia onset was 18days (range 1-180) with a median age of nadolol initiation of 30days (range 11-390). Of the 20 regular narrow complex tachycardia patients initiated on nadolol monotherapy, 85% had no recurrences as of 1-year follow-up. Side effects were suspected in 3 of 28 (10.7%), including wheezing (n=1, 3.5%), irritability and diarrhea (n=1, 3.5%), and bradycardia (n=1, 3.5%). Oral nadolol suspension was a successful treatment for SVT in 85% of patients with minimal adverse effects. Single daily dosing was used in the majority of patients.

Safety and efficacy of paramedic treatment of regular supraventricular tachycardia: a randomised controlled trial

IntroductionSupraventricular tachycardias (SVTs) are a common cause of acute hospital presentations. Adenosine is an effective treatment. To date, no studies have directly compared paramedic-with hospital-delivered treatment of acute SVT with...

Supraventricular tachycardias: differential diagnosis at bedside and in the electrophysiology laboratory

AbstractClinical and electrophysiologic criteria used for the differential diagnosis of regular supraventricular tachycardias (SVT) are presented. Although several electrocardiographic clues may assist differential diagnosis, this is usually accomplished at electrophysiology study and, most often, is between atrioventricular nodal reentrant tachycardia, atrioventricular reentrant tachycardia due to a concealed accessory pathway, and atrial tachycardia. Atrial and, mainly, ventricular pacing maneuvers during sinus rhythm or tachycardia have been used with variable success rate. In clinical practice, these techniques cannot be applied to all cases, and multiple criteria have to be used for the differential diagnosis of narrow complex tachycardias with atypical characteristics.Answer questions and earn CME: https://wileyhealthlearning.com/Activity2/4469457/Activity.aspx

Diagnostic Accuracy of Several Electrocardiographic Criteria for the Prediction of Atrioventricular Nodal Reentrant Tachycardia

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common form of paroxysmal supraventricular tachycardia (SVT) whose diagnosis can be strongly suspected based on the surface eletrocardiogram alone. The purpose of this study is to determine the diagnostic accuracy of several electrocardiographic (ECG) criteria for the prediction of AVNRT. Between November 2010 and January 2014, a total of 256 patients who underwent electrophysiological testing (EP) with regular, paroxysmal and narrow QRS complex tachycardia were prospectively enrolled. We classified the ECG recordings during tachycardia for the presence of the following criteria: a) classical ECG findings of pseudo S wave in inferior leads and/or pseudo r' wave in lead V1, b) notch in lead aVL, c) no retrograde P waves visible during tachycardia; d) pseudo r' wave in lead aVR, e) notch in lead D1, f) any deflection after 100ms of the QRS complex during tachycardia. On multivariate analysis, independent predictors of AVNRT diagnosis were female sex (OR 4.17; 95% CI [2.11-8.24]; p <0.001), age >60years (OR 3.53; 95% CI [1.25-9.96]; p=0.017) and the classical ECG criteria (OR 7.41; 95% CI [3.62-15.17]; p <0.001). Female, age >60years and the classical ECG criteria were the independent predictors of AVNRT diagnosis. Although several of the ECG criteria for AVNRT diagnosis showed acceptable sensitivities and specificities, they do not improve its accuracy.

Ventricular arrhythmias and sudden cardiac death

### Key points There are 50–100 unexpected, sudden cardiac deaths (SCDs) per 100 000 population per year in Europe and USA, categorized by symptom onset to cardiac arrest time of <1 h.1 Despite the decline in coronary artery disease mortality and advancements in resuscitation services, survival from these events remains low. Unfortunately, they often occur outside the hospital environment and are associated with a survival rate of <10%. The majority occur in adults over 35 yr of age and at least half of these events can be attributed to ventricular arrhythmias, although the true incidence is unknown due to inevitable degeneration to asystole if unwitnessed. These arrhythmias may be the presenting complaint in the emergency department and may feature throughout the perioperative period, including at preoperative assessment, during surgery and in the recovery phase, for example in intensive care. They may also be the direct target of therapy in the case of electrophysiological catheter ablation and implantable cardioverter defibrillators (ICDs). They are more frequent and carry greater risks in patients with structural heart disease, but younger patients with ion-channel abnormalities can also be susceptible.2 This review classifies the causes and significance of ventricular arrhythmias based on the presence or absence of structural heart disease and provides a simple system to aid confident distinction from supraventricular arrhythmias. …

Recurrent symptomatic regular tachycardia

Recurrent symptomatic regular tachycardia

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FigureStudy objective: The use of chicken soup in the symptomatic treatment of infectious disease is a well-known home remedy for the relief of symptoms and well-being advocated by mothers all over the world. We could find no published clinical trials, however, involving the use of chicken soup in the ED. Our goal was to see if the addition of chicken soup with standard treatment would improve patient's disposition and treatment outcome. Methods: This non-controlled, non-blinded, non-randomized prospective study in a single center offered patients who presented to our ED with any complaints vaguely relating to an infectious disease treatment with chicken soup as part of their standard treatment. They were given a visual seven-point scale to report whether they were feeling better at disposition. Statistical analysis subsequently determined outcome improvement and patient satisfaction scores. Results: Originally 1,989 patients were to be enrolled, but significant improvement in outcome was noted on early review of cases. The study was ended, and the use of chicken soup was added to standardized treatment protocols. Conclusion: Mom was right. Chicken soup does improve all areas of measurement including patient improvement, satisfaction, and outcomes scores. Decrease in Time to Defibrillation with the Use of a Remote Device BY DR. HOWARD, DR. FINE, & DR. HOWARD Introduction: Time to defibrillation/cardioversion (shock) in ventricular dysthymias has been shown in multiple studies to be the rate determinate step in outcomes for cardiac arrest victims. Decrease in time to shock has been shown by other studies to improve outcome in cardiac arrest victims. Our study was proposed to see if we could decrease this time interval by using a remote-controlled handheld device to initiate shock by the code leader.FigureConclusion: Our study showed a decrease in time-to-shock by the use of a remote-controlled handheld device to initiate electrical shock in cardiac arrest patients in ventricular dysrhythmias, Times were not statistically significant because several outlier times messed up the results. These prolonged times to shock were looked at individually, and it appeared that the inability to find the remote contributed to the most significant time delays for those outliers. Future research should focus on how to make this process more efficient. We suggest incorporating the shock button into an app on cellular phones.FigureUsing the Long Outward Exhalation (LOX) Maneuver for Conversion of SVT in the Emergency Department BY D. ELI, MD, K. OSHER, DO, & B. AGEL, MD We report a case of SVT that was successfully converted using a previously unreported technique for the cessation of SVT. An 18-year-old man presented to the ED with a fast heart rate. He denied any chest pain, lightheadedness, or shortness of breath. He also denied previous history of fast or irregular heart rate, family history, or recent ingestions of alcohol, sympathetic drugs, or tobacco. The patient was alert, in no distress, and had a heart rate of 180 bpm and stable vital signs. His ECG showed a narrow complex regular tachycardia with a rate of 180. He was placed in a monitored room, a plain untoasted bagel was placed over his flips, and it was explained to him to use a long outward exhalation (LOX) for 15 seconds. This maneuver was tried twice without any success. After further discussion, we decided to place a piece of lox (salt-cured salmon) over the hole of the bagel. The patient was again instructed to take a long outward exhalation after placing the bagel and lox over his mouth. Conversion was almost immediate. Repeat ECG showed normal sinus rhythm with no changes. He was discharged home to follow-up with primary care in two to three days. We hypothesized that exhaling through a plain bagel did not generate enough resistance to simulate a Valsalva maneuver, once but the lox applied to the outside of the bagel acted as a flutter valve, generating a 40 mm Hg pressure and 15 s strain, which has been shown to be needed for conversion. Further studies are needed to determine whether the LOX maneuver needs to be modified (i.e., toasting, cream cheese). Better late than never, we always say. These April Fool's Day gems were brought to you byStuart Etengoff, DO, an emergency physician at Genesys Regional Medical Center in Grand Blanc, MI. In case you were wondering about the authors on these case reports, the first one was Dr. Oy Vey for the exclamation used by Jewish mothers everywhere when serving chicken soup to sick family members. C(hicken) N(oodle) Campbell stood for the soup. The authors of the second item were the last names often used by the Three Stooges when they played doctors on their show. The third case report used the words deli, kosher, and bagel as stand-ins for the doctors' names.

High-Dose Adenosine for Treatment of Refractory Supraventricular Tachycardia in an Emergency Department of an Academic Medical Center: A Case Report and Literature Review

BackgroundSymptomatic tachycardia is a common admission diagnosis in the emergency department (ED). This can be a life-threatening condition and requires immediate attention. Supraventricular tachycardia (SVT) is commonly treated with adenosine, and successful treatment is limited to atrioventricular (AV) node-dependent SVTs as adenosine causes a transient heart block. However, there are limited data available for instances when the recommended dosing regimen (6 mg, 12 mg, 12 mg) fails to terminate SVT. Case ReportA 33-year old man was evaluated in the ED with an electrocardiogram revealing a regular narrow complex tachycardia with a heart rate of 180 beats/min and a rhythm consistent with SVT. He reported experiencing 3 days of fatigue, myalgias, palpitations, and dyspnea on exertion, but was otherwise hemodynamically stable. Attempts at chemical cardioversion with standard doses of adenosine (6 mg, 12 mg, and 12 mg) were given without success. After consultation with the cardiology service, additional doses of 24 mg and then 36 mg of adenosine were administered. The last dose of 36 mg produced sustained conversion and return to a normal sinus rhythm. The patient later underwent radiofrequency ablation of a left-sided orthodromic reciprocating accessory pathway. After 3 months of medical management, the patient had an implantable cardiac defibrillator placed for prevention of sudden cardiac death. Why Should an Emergency Physician Be Aware of This?Each case of SVT demands immediate attention from an emergency physician. It is imperative that providers be aware of the limitations of adenosine and when it may be appropriate to deviate from standard dosing recommendations. This is in addition to collaborating with an expert in cardiac electrophysiology when initial management tactics are not successful.

Accidental Entrapment of Electrical Mapping Catheter by Chiari's Network in Right Atrium during Catheter Ablation Procedure.

A 78-year-old male was admitted to our hospital due to frequent palpitation. His electrocardiogram (ECG) presented regular narrow QRS tachycardia with 170 bpm, and catheter ablation was planned. During electroanatomical mapping of the right atrium (RA) with a multiloop mapping catheter, the catheter head was entrapped nearby the ostium of inferior vena cava. Rotation and traction of the catheter failed to detach the catheter head from the RA wall. Exfoliation of connective tissue twined around catheter tip by forceps, which were designed for endomyocardial biopsy, succeeded to retract and remove the catheter. Postprocedural echocardiography and pathologic examination proved the existence of Chiari's network. The handling of complex catheters in the RA has a potential risk of entrapment with Chiari's network.