Regular Supraventricular Tachycardia Research Articles

Patients with drug-refractory atrioventricular nodal reentrant tachycardia: Clinical features, electrophysiological characteristics, and predictors of medication failure

Background and purposeDrug responses vary markedly from patient to patient in atrioventricular nodal reentrant tachycardia (AVNRT), the most common form of paroxysmal regular supraventricular tachycardia in adults. However, clinical and electrophysiological (EP) characteristics of patients with AVNRT whose tachycardia attacks could not be adequately controlled by antiarrhythmic agents have not been studied in a large patient cohort. We aimed to define the clinical and EP features of patients with drug-refractory AVNRT. Methods and resultsA total of 266 consecutive patients with AVNRT undergoing catheter ablation after a period of medical treatment were analyzed: 144 patients with drug-refractory AVNRT (Group 1) and 122 patients with drug-responsive AVNRT (Group 2). Age was significantly higher (p=0.027) and the presence of hypertension (p=0.030), diabetes mellitus (p=0.047), and valvular heart diseases (p=0.008) was more frequent in Group 1 compared to Group 2. Among the EP features, atrial-His jump (81% vs 69%, p=0.028) and atrial vulnerability (26% vs 14%, p=0.018) were significantly higher, echo zone was significantly more long-lasting (44±24ms vs 38±22ms, p=0.018), and tachycardia cycle length (TCL) was significantly longer (348±41ms vs 329±38ms, p=0.000) in Group 1 than in Group 2. Multivariate analysis showed that hypertension (p=0.036), valvular heart disease (p=0.014), atrial vulnerability (p=0.037), TCL (p=0.003), and wide echo zone (p=0.028) were independent predictors for drug-refractory AVNRT. ConclusionIn the presence of hypertension, valvular heart disease, atrial vulnerability, long-lasting echo zone, and relatively slow AVNRT, medical treatment is less likely to prevent the tachycardia episodes.

071 SAFETY AND EFFICACY OF PARAMEDIC TREATMENT OF REGULAR SUPRAVEENTRICULAR TACHYCARDIA:

<h3>Introduction</h3> Treatment of supraventricular tachycardia (SVT) with adenosine by paramedics has been investigated and proven to be safe in the USA, but patients (pts) are transferred to hospital. We hypothesised that paramedics can safely treat and discharge pts with regular SVT without transfer to an accident and emergency department and tested this in a randomised controlled trial. <h3>Methods</h3> Pts presenting with regular narrow complex tachycardia on 12 lead ECG who were heamodynamically stable, with no history of structural or ischaemic heart disease and without contraindication to adenosine were considered for enrolment. Pts were randomised to paramedic treatment (PARA) or admission to hospital (A&amp;E). PARA pts received valsalva manoeuvre at the scene with subsequent administration of 6 mg and 12 mg of adenosine unless the SVT terminated. Pts were taken to A&amp;E if the tachycardia did not terminate, restarted, or the patient (pt) had continuing symptoms, a persistently abnormal ECG (other than T wave inversion) or was heamodynamically unstable. Prior to discharge from the ambulance pts received an information pack and a referral letter for their GP to refer them to an arrhythmia clinic. Pts randomised to A&amp;E were treated as normal and given no information other than that pertaining to the study. <h3>Results</h3> Of the 60 pts (33=F, age 52±19 years) enroled to date, 56% pts had previously attended A&amp;E with palpitations. 2 pts withdrawn as lost to follow up. Results table&nbsp;1 PARA discharge times were relatively long because 12 pts randomised to PARA were transported to A&amp;E (5 did not terminate arrhythmia, 1 abnormal observations, 4 paramedic felt ECG abnormal (confirmed as minor abnormalitites by expert panel that would not require treatment), 2 abnormal ECG requiring treatment). A panel of 2 arrhythmia experts reviewed records for all PARA pts and confirmed treatment was appropriate for all but would have further assessed 1 pt with lung disease. <h3>Conclusions</h3> Paramedic treatment and discharge of pts with regular SVT is safe, efficacious and reduces admissions. Cost effectiveness analysis is ongoing.

Are patients admitted to emergency departments with regular supraventricular tachycardia (SVT) treated appropriately?

Regular supraventricular tachycardia (SVT) is frequently encountered in clinical practice. Guidelines are available from the National Service Framework (NSF) for the treatment of patients attending emergency departments (ED) with SVT. These recommend a thyroid-function test (TFT) and arrhythmia electrocardiography (ECG), and referral to a heart-rhythm specialist on discharge. Hospital admission is rarely required. In our multicentre study, we examined the implementation of these guidelines among patients attending the ED with SVT. Only 34% of patients had specialist referrals, with an average wait of 50.3 days (the majority of delays resulted from referral requests from general practitioners). A history of previous SVT, the mode of tachycardia termination, patient age and/or comorbidities were similar for the 27 (23.5%) patients who were admitted overnight. Of these, 15 (13%) of the total 115 patients who attended ED with regular SVT were referred for Holter monitoring despite having ECGs demonstrating arrhythmia. Low referral rates, unnecessary investigations and admissions indicate a need for improvement for better patient care and to minimise healthcare costs. We have formulated a standard operating procedure, which will be available via the College of Emergency Medicine website.

Wolff-Parkinson-White syndrome and antidromic atrioventricular reentrant tachycardia

This editorial refers to ‘Incidence and prognostic significance of spontaneous and inducible antidromic tachycardia’ by B. Brembilla-Perrot et al. , on page 871. The prevalence of regular paroxysmal supraventricular tachycardia (SVT) is 2.25/1000 persons and the incidence is 35/100 000 person-years, according to data from the Marshfield Epidemiologic Study Area. Thus, there are ∼570 000 patients, and 89 000 new cases/year with SVT in the US alone. In most parts of the world, atrioventricular reentrant tachycardia (AVRT), due to Wolff–Parkinson–White (WPW) syndrome or a concealed accessory pathway, is the second most common cause of SVT (after AV nodal reentrant tachycardia), and accounts for up to one-third of all SVT. In China, WPW syndrome is the most common cause of SVT, being responsible for more than 70% of cases.1 In Western countries, the prevalence of WPW syndrome is 0.1–0.3%.1 Thus, despite the fact that accessory pathways have been continually eliminated in electrophysiology laboratories during the last two decades, WPW syndrome is not likely to become extinct. Clear indications for catheter ablation in patients with WPW syndrome are not established. In patients with asymptomatic pre-excitation, the risk of sudden cardiac death is low, ∼1.25/1000 person-years.2 Symptomatic patients have …

Interatrial mechanical dyssynchrony shown by tissue doppler imaging during atrial flutter

Although regular supraventricular tachycardia is traditionally classified on the basis of P-wave morphology, diagnostic accuracy is limited to information obtained from surface electrocardiography. Intracardiac electrophysiology is a conclusive although invasive diagnostic method. We report a case of regular supraventricular tachycardia with a heart rate of 162 bpm. M-mode echocardiography of the interatrial septum clarified both the atrial rate and the ventricular response ratio. Tissue Doppler M-mode imaging demonstrated the delay between the posterior wall motion of the left and right atrium. Although it deserves further study, transthoracic echocardiography may provide useful information in addition to electrocardiography.

Simultaneous conduction over the fast and slow pathways during induction of atrioventricular nodal reentrant arrhythmia with a rate of less than 100 bpm and infra-His block after radiofrequency ablation of the slow pathway

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common form of paroxysmal regular supraventricular tachycardia in adults. It is typically induced with an anterograde block over the fast pathway (FP) and conduction over the slow pathway (SP), with subsequent retrograde conduction over the FP. Rarely, a simultaneous conduction of a premature atrial complex occurs over the FP and SP to induce AVNRT and is called "one for two phenomenon". We present a 46-year-old woman with atrioventricular nodal rhythm with a rate of 95 beats per minute with distinct electrophysiological characteristics showing simultaneous conduction over the FP and SP during induction of tachycardia and an infra-His block after radiofrequency ablation of the SP.

Utility of the aVL lead in the electrocardiographic diagnosis of atrioventricular node re-entrant tachycardia

Reciprocating atrioventricular tachycardia can be categorized into common slow-fast atrioventricular node re-entrant (AVNRT) and orthodromic atrioventricular reciprocating tachycardia (AVRT). The electrocardiogram (ECG) during tachycardia is useful in distinguishing these two mechanisms. The presence of a pseudo-R'-wave in lead V1 or pseudo-S-wave in the inferior leads has been widely used, although the value of an isolated aVL lead has not been evaluated yet. To determine whether an isolated aVL lead of the surface 12-lead ECG is useful for the differential diagnosis between AVNRT and AVRT. Consecutive patients referred for paroxysmal regular supraventricular tachycardia radiofrequency ablation were prospectively evaluated. Patients with atrial tachycardia, bundle branch block, manifested pre-excitation, and those undiagnosed after electrophysiology study were excluded. We compared the standard criteria with the value of an isolated aVL lead to distinguish between AVNRT and AVRT. One hundred and one patients were included; 73.3% were AVNRT and 26.7% AVRT. Patients with AVNRT were older (49.4 +/- 16.4 vs. 36.0 +/- 18.7 years, P = 0.001). The aVL notch and the standard criteria were found more frequently in AVNRT than in AVRT (aVL notch: 51.3 vs. 7.4%, P< or = 0.001; pseudo-S-wave 45 vs. 8.6% P = 0.001; and pseudo-R'-wave in V1 39.7 vs. 11.5%, P = 0.008, respectively). The aVL notch sensitivity and specificity to determine the final diagnosis were higher than the standard criteria (aVL notch 48.6 and 92.6%; pseudo-S-wave 45 and 91.3%; and pseudo-R'-wave in V1 39.7 and 88.5%, respectively). The presence of a notch in aVL lead appeared to be as sensitive and specific as the standard electrocardiographic criteria for the differential diagnosis of AVNRT.

A randomized-controlled trial comparing conventional with minimal catheter approaches for the mapping and ablation of regular supraventricular tachycardias

To compare the use of a minimal (MIN) with a conventional (CON) catheter approach for the mapping and ablation of regular supraventricular tachycardias (SVT) and typical atrial flutter (AFL) in the setting of a randomized-controlled trial. Two hundred patients (age 51.2 +/- 15.9 years, 99 male) were randomized to a MIN or CON group. The MIN approach involved using two catheters for AFL, one to three for other SVT (ablation catheter included), whereas the CON approach involved three and five catheters, respectively. Acute procedural success was similar between the two groups. There was no significant difference in overall procedure times, fluoroscopy times, or radiation doses. Procedure times were shorter for AFL ablation in MIN compared with CON [60 (30-150) vs. 85 (40-200) min, median (range), P = 0.03] from subgroup analysis. A median of three (one to six) catheters was used in MIN and five (three to seven) in CON (P < 0.0001). Catheter costs were significantly lower in MIN compared with CON [6.1 (2-61) vs. 8.5 (4.4-21.3) units, P < 0.0001, where one unit is equivalent to the cost of a diagnostic quadripolar catheter]. At 6-week follow-up, two patients in MIN (2.1%) and three patients in CON (3.2%) had documented recurrence of the index arrhythmia. The use of a MIN approach in the treatment of SVT and AFL is as effective, quick, and safe as using a CON approach and is therefore more cost-effective.

Atrioventricular node anatomy and physiology: implications for ablation of atrioventricular nodal reentrant tachycardia

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common arrhythmia in patients with regular supraventricular tachycardia. Selective radio frequency catheter ablation of the slow pathway has afforded an ideal method to treat most patients with AVNRT. However, there are still some controversies and recent developments concerning the ablation for patients with AVNRT. The purpose of this review is to elucidate the anatomy and physiology of the atrioventricular node and implications for the ablation of AVNRT. The sequential ablation sites for slow pathway ablation are suggested as the isthmus between tricuspid annulus and coronary sinus ostium, the tricuspid edge of coronary sinus ostium by moving the ablation catheter tip slightly in and out of the coronary sinus, the septum lower than coronary sinus ostium, moving higher up on the half of Koch's triangle along the septum, one or two burns inside the first centimeter of the coronary sinus, left side of the septum. It is imperative to recognize the detailed anatomy and physiology of the atrioventricular node in every individual patient before the ablation of AVNRT.

Current case mix and results of catheter ablation of regular supraventricular tachycardia: are we giving unrealistic expectations to patients?

Catheter ablation (CA) has become the treatment of choice for regular supraventricular tachycardia (SVT). The purpose of this study was to investigate whether the current clinical results in a large single centre are as good as success rates quoted to patients from published trials and national cardiology society websites. We recorded and analysed prospectively the acute and follow-up (FU) results of all CA procedures performed for SVT at our institution over a 2-year period. We compared our results with the success rates of 90-98% for CA quoted in the literature. We performed a total of 547 CA at our institution over 2 years, of which 389 (71%) were for regular SVT. Of these, 71 procedures (18%) were redo procedures. The overall acute procedural success rate was 96.1% (374/389). Follow-up data were available for 367 of 389 (94.3%) procedures. The overall 6-week success rate varied between 74.7 and 91.3% depending on the SVT type (average 83.9%). The FU success rates were lower for redo procedures (47/66, 71.2%) when compared with first ablation (de novo) procedures (261/301, 86.7%), P = 0.003. Published success rates are much better than current success rates in a large single centre. It is possible that the information regarding outcome given to patients during the consent process is not accurate.

Supraventricular tachycardia with simultaneous atrial and ventricular activation: What is the mechanism?

A 50-year-old man underwent an electrophysiologic study for very frequent episodes of supraventricular tachycardia. He had a left bundle branch block with a baseline sinus cycle length, atrial-His (AH) interval, and His-ventricular (HV) interval of 670, 100, and 65 ms, respectively. Atrial pacing induced a regular supraventricular tachycardia with a cycle length of 540 ms. Ventricular pacing at a cycle length of 500 ms was performed during the tachycardia (Figure 1). A premature atrial stimulus was introduced in the high right atrium during tachycardia (Figure 2).

Electrophysiologic characteristics and results of radiofrequency catheter ablation in elderly patients with atrioventricular nodal reentrant tachycardia

Background As in the general population, atrioventricular nodal reentrant tachycardia (AVNRT) is the most common regular supraventricular tachycardia in the elderly patients. We tried to compare electrophysiologic characteristics, efficacy, and risks of the radiofrequency (RF) catheter ablation of the slow pathway in elderly and young patients with AVNRT. Methods Between April 2001 and March 2005, 268 consecutive patients (190 females; mean age, 49 ± 14 years) with AVNRT underwent RF catheter ablation at our institution. The patients were categorized into 2 groups: group 1 consists of patients younger than 65 years (n = 156), and group 2 consists of patients 65 years or older (n = 112). Results Compared with the younger subgroup, elderly patients more often had structural heart disease (11.6% vs 2.5%, P = .004), but there were no statistically significant differences in sex and symptoms during tachycardia (all P > .05). AVNRT cycle length was significantly longer in group 2 than in group 1 patients ( P = .005). Among the conduction intervals of tachycardia, only atrio-his interval was significantly longer in group 2 patients ( P = .007). The ablation fluoroscopy time, RF pulse duration, target temperature, applied energy, and number of RF applications were comparable in the 2 groups (All P > .05). Risk of atrioventricular block, pericardial effusion, and vascular thrombosis were similar in both groups (All P > .05). During follow-up with duration of 14 months, similar rate of recurrence was observed in the 2 groups ( P = .94). Conclusions In elderly patients, slow pathway ablation is as effective and safe as in younger patients. Therefore, when considering different treatment options in elderly patients, an increased risk of complications or lower efficacy should not be a factor in determining the best therapeutic approach.

Clinical and Electrophysiologic Characteristics and Efficacy of Radiofrequency Catheter Ablation of the Elderly Patients with Atrioventricular Nodal Reentrant Tachycardia

Background and Objectives：Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common regular supraventricular tachycardias in both the general population and elderly patients. The aim of this study is to investigate the clinical and electrophysiologic characteristics and efficacy of radiofrequency catheter ablation (RFCA) for treating AVNRT in the elderly. Subjects and Methods：This study included 273 consecutive symptomatic AVNRT patients who underwent RFCA for the slow-pathway. The study population was divided into two groups: group I patients were younger than 65 years (n=227, average age: 44.6±12.9 years, male：female=89：138) and group II patients were older than 65 years (n=46, average age: 69.0±3.6, male：female=9：37). We compared the baseline clinical, electrocardiographic and electrophysiologic characteristics and the outcomes of RFCA between the two groups. Results：The prevalence of a baseline prolonged PR interval (>200 ms) was not different between the 2 groups (1.8% vs. 6.5%, p>0.05). The baseline sinus cycle length, QT interval and AVNRT cycle length were significantly longer in group II than in group 1 (799.3±146.1 ms vs. 864.3±159.8 ms, 374.2±42.1 ms vs. 397.6±40.4 ms, 351.3±43.2 ms vs. 384.9±57.0 ms, respectively p 0.05). One patient in group I required permanent pacemaker implantation. Conclusion：RFCA in elderly patients is safe and effective as in younger patients. Therefore, performing RFCA for treating AVNRT should also be considered in the elderly patients. (Korean Circulation J 2006;36:354-358)

Mechanism of Transition from Irregular to Regular Supraventricular Tachycardia

Mechanism of Transition from Irregular to Regular Supraventricular Tachycardia

37 Recurrence of atrial fibrillation after efficacious radiofrequency transcatheter ablation of regular supraventricular tachycardia

37 Recurrence of atrial fibrillation after efficacious radiofrequency transcatheter ablation of regular supraventricular tachycardia

37 Recurrence of atrial fibrillation after efficacious radiofrequency transcatheter ablation of regular supraventricular tachycardia

37 Recurrence of atrial fibrillation after efficacious radiofrequency transcatheter ablation of regular supraventricular tachycardia

Efficacy and Safety of Radiofrequency Catheter Ablation of Atrioventricular Nodal Reentrant Tachycardia in the Elderly

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common regular supraventricular tachycardia in the general population as well as in elderly patients. The purpose of the study was to investigate the success and complication rate particularly regarding the induction of an atrioventricular (AV) block by radiofrequency (RF) ablation in elderly patients with and without a preexisting AV block. Between February 1998 and July 2004, all patients with symptomatic AVNRT referred for slow-pathway ablation in our institution were included and divided into two groups: group 1 patients younger than 75 years (n = 508) and group 2 patients > or =75 years (n = 70). A preexisting prolonged PR interval was present in 17 (3.3%) patients of group 1 and in 26 (37%, P < 0.0001) patients of group 2. Following successful slow-pathway ablation (follow-up time group 1: 37 +/- 22, group 2: 37 +/- 24 months) no induction of an AV block was observed in group 2 but in four patients of group 1 (0.79%) a complete heart block was induced requiring a pacemaker implantation. In group 1, 15 (2.95%) patients with a recurrence of AVNRT were readmitted for a repeat ablation procedure. No recurrences occurred in group 2. Despite a higher incidence of preexisting prolonged PR intervals slow-pathway ablation in elderly patients is both effective and safe and should be considered as the first line therapy also in this patient population.

Analysis of electrophysiological activity in Koch's triangle relevant to ablation of the slow AV nodal pathway.

Atrioventricular junctional reentrant tachycardia (AVJRT) is the most common form of paroxysmal regular supraventricular tachycardia. In patients with disabling, drug refractory AVJRT, catheter ablation has evolved rapidly from a last-resort treatment in the form of interruption of atrioventricular (AV) conduction to selective modification of AV nodal function as an ideal treatment. This article will focus on the frequently unappreciated electrophysiological activities recordable in man in Koch's triangle during ablation of the so-called slow pathway.

Using the right drug: a treatment algorithm for regular supraventricular tachycardias.

Despite the recent advent of and the successful results from catheter ablation, pharmacological therapy is still used by most clinicians as the first line therapy in patients with regular supraventricular tachycardias. Before prescribing an antiarrhythmic agent, documentation of the arrhythmia using a 12-lead electrocardiogram (ECG) is necessary to identify the type of tachycardia. The ECG diagnosis is based on the presence and polarity of the P wave, the P to QRS relationship, the presence of QRS alternation and the effect of bundle branch block on tachycardia rate. Most regular supraventricular tachycardias use the atrioventricular node either passively, as in atrial tachycardias or flutter, or actively, as paroxysmal junctional tachycardias. The Sicilian Gambit approach attempted to introduce some rationale in the choice of an antiarrhythmic agent, taking into account tachycardia mechanism, by defining the critical components of the tachycardia and the vulnerable parameter, i.e. the component that may readily be affected by an appropriate antiarrhythmic agent. For this approach, an electrophysiological study is particularly useful. The most common regular paroxysmal supraventricular tachycardias include atrioventricular nodal re-entrant tachycardias and atrioventricular re-entrant tachycardias which use an overt or concealed accessory atrioventricular connection (Kent bundle) or atriofascicular connection (Mahaim). For acute termination of paroxysmal junctional tachycardia, intravenous adenosine is the drug of choice. For the prevention of the tachycardia attacks in atrioventricular nodal re-entrant tachycardia, the agents with a depressive effect on the antegrade slow pathway, such as calcium channel blockers or beta-blockers, are likely to be effective. If they fail, sodium channel blockers (propafenone or flecainide) may be indicated. In tachycardias involving accessory connections, agents that affect fast channel dependent tissue (propafenone, flecainide, cibenzoline, disopyramide or hydroquinidine) are effective. Potassium current blockers, such as sotalol or amiodarone, represent an alternative therapy. In atrial tachycardias, the use of propafenone, flecainide or sotalol constitute a logical choice. In drug-resistant cases, amiodarone is the most potent agent. Radiofrequency ablation of the slow atrioventricular nodal pathway, of an accessory connection or of an atrial focus, is indicated in drug-resistant or drug-intolerant patients and is increasingly offered as an alternative therapy.

Can patients discriminate between atrial fibrillation and regular supraventricular tachycardia?

The clinical diagnosis of the cause of palpitations in the absence of electrocardiographic documentation relies on the patient's description of the symptoms. Palpitations may be described as regular or irregular and some estimate of the their rapidity may be obtained. In conjunction with other observations, including duration, onset characteristics and precipitating factors, a clinical diagnosis of arrhythmias such as paroxysmal atria1 tachycardia, atria1 fibrillation.or ectopic beats can be made. 1–3 The relation between these symptoms of tachycardia and actual arrhythmias has not been subjected to systematic evaluation. This pilot study examined whether patients could reliably differentiate an irregular tachycardia (atria1 fibrillation) from regular reciprocating tachycardia during an electrophysiologic study. In addition, the use of a simple analog scale to estimate tachycardia cycle length was evaluated.