Termination Of Supraventricular Tachycardia Research Articles

Comparison of initial adenosine dose conversion rate for supraventricular tachycardia in the emergency department

ObjectiveTo evaluate the rate of supraventricular tachycardia (SVT) termination between 6 mg and 12 mg initial adenosine doses. MethodsThis multi-center, retrospective cohort study evaluated patients presenting to the emergency department (ED) from January 1, 2020 to June 30, 2022 in SVT and received adenosine. The primary objective of the study is to compare the rate of SVT termination between adenosine 6 mg and 12 mg as documented on a formal electrocardiogram. Secondary endpoints include termination of SVT with subsequent adenosine dose, time to ED disposition, adverse effects, and subgroup analyses of patients with a body mass index greater than or equal to 40 kg/m2 and a history of SVT. ResultsOf 213 patients included, a 6 mg initial adenosine dose was administered to 117 patients (54.9 %) and a 12 mg initial adenosine dose was administered to 96 patients (45.1 %). SVT termination following the initial dose of 6 mg or 12 mg was 56.4 % and 79.1 %, respectively (p < 0.001). Among the 46 patients who failed to terminate SVT with an initial 6 mg dose, 33 converted to sinus rhythm with a subsequent adenosine dose in comparison to 1 of the 7 patients receiving an initial dose of 12 mg (71.7 % vs 14.3 %, p = 0.007). Median time to ED disposition, either inpatient admission or discharge, was 209 and 161 min, respectively (p = 0.104). There was no statistical difference in either subgroup analyses. ConclusionA higher rate of SVT termination was observed with an initial adenosine dose of 12 mg in the ED in comparison to the guideline recommended dose of 6 mg. There were no significant differences in adverse effects observed.

The Effectiveness of Physical Maneuvers in the Conversion of Supra-Ventricular Tachycardia on the Example of the Valsalva’s Maneuver

The Valsalva maneuver (VM) is one of the physical maneuvers used by medical personnel. In emergency medicine, it is known primarily for its use as a non-pharmacological method of restoring sinus rhythm possible to perform in almost every patient, and side effects are noticed incidentally. A distinction is made between the classic and the modified Valsalva tests. Multiple studies confirm its use and effectiveness in cases of supraventricular tachycardia episodes in hemodynamically stable patients. The VM allows to determine heart failure by showing abnormal rise of blood pressure as a response to the Valsalva test and thus suggests impaired ventricular function. This maneuver lowers the preload and thus the enddiastolic volume, thereby enhancing some murmurs and weakening others. As a result of phase IV of VM, clinically significant bradycardia occurs, which is used for, at least temporary, termination of supraventricular tachycardia. Based on the available literature, the effectiveness of the modified Valsalva sample was almost twice as high as that of the classical method. However, both methods are effective in the conversion of supra-ventricular tachycardia. Its implementation is relatively simple and possible to perform for almost any patient, provided that he cooperates. As majority of patients using the services of sanatoriums are people burdened with numerous diseases, including cardiovascular diseases, some of them may present with supraventricular tachycardia. Hence, it is important to know simple, safe and non-pharmacological methods of stopping it, the most common of which is the Valsalva maneuver.

Abstract 10470: Comparison Between the Double-Syringe Technique and the Single-Syringe Diluted with Normal Saline Technique of Adenosine for a Termination of Supraventricular Tachycardia: A Pilot, Randomized, Single-Blind Controlled Trial (Do-Single Trial)

Introduction: Supraventricular tachycardia (SVT) is a condition commonly found in emergency settings. Adenosine is recommended as the first-line treatment for stable patients, however, it is rapidly metabolized. The ACLS guidelines recommend administration of 6-mg adenosine intravenously (IV) with an immediate 20-ml normal saline solution (NSS) IV (double syringe technique; DST). However, adenosine diluted with NSS up to 20 ml IV (single syringe technique; SST) was as well found effective for terminating the arrhythmia. Hypothesis: The SST is non-inferior to the DST for terminating stable SVT. Methods: A pilot, single-blind, randomized, controlled study was conducted from January to December 2020 at 4 hospitals in the northeastern region, Thailand. Thirty patients who presented with stable regular narrow complex tachycardia, diagnosed as stable SVT by cardiologists, were enrolled. They were randomized into the DST and SST groups, 15 patients each. We evaluated the termination of SVT (turned to normal sinus rhythm), the average successful doses, and the complication rate of each group. Analyses were based on the intention to treat principle. Results: The termination rate was 91.7% and 83.3% in the DST and the SST group, P =0.990. The success rate of 6-mg adenosine was 75% and 66.7% in the DST and the SST group, P =0.640. The total administration dose was 8.2±4.9 mg in the DST group, and 10.0±5.9 mg in the SST group, P =0.432. There was no difference in the complication rate between both groups. Conclusions: Adenosine diluted with NSS up to 20 ml administered IV was non-inferior to the conventional technique for terminating SVT. A further definitive study with larger sample size is required.

When Valsalva Triggers SVT, Consider AVNRT

Patients with supraventricular tachycardia (SVT) episodes frequently present to the Emergency Department (ED). Valsalva manoeuvre termination of SVT is well described, however its ability to precipitate SVT is seldom mentioned in the literature. We present three cases of Valsalva=like manoeuvres precipitating SVT. In this series, two cases were confirmed AV-nodal re-entrant tachycardia (AVNRT) and one suspected.

Modified Valsalva Versus Standard Valsalva for Cardioversion of Supraventricular Tachycardia: Systematic Review and Meta-Analysis

Background: Supraventricular tachycardia (SVT) is a major cause of emergency room visits where vagal manoeuveres are used as first-line therapy. The Valsalva manoeuvere (VM) is proven to be safe and, to some extent, effective in terminating SVT episodes. Data on a refined version (i.e., the modified Valsalva manoeuvere (MVM)), have suggested superior efficacy. In this systematic review, we aim to compare the standard VM (SVM) to the MVM. We hypothesised that MVM is more effective in terminating SVT episodes and reducing the time spent in the emergency department. Methods: In this systematic review and meta-analysis, we searched Pubmed (Medline and PubMed central), Evidence-Based Medicine review databases via Ovid, Web of Science, Cochrane databases using Medical Subject Headings (MESH) and the references of included studies with no restriction in either date or language. We included only RCTs that compared modified and standard Valsalva manoeuvere in treating SVT and included one of our primary and secondary outcomes. Our main outcome was the termination of SVT within 1 minute with MVM or SVM. We used pooled risk ratio (RR) for the main outcome. Findings: We identified four articles that met our inclusion criteria. Sinus rhythm was achieved 2·5 times more in the MVM group compared to the SVM group (risk ratio (RR) = 2·54, CI 1·98–3·24, P < 0·001), thus lowered the need of intravenous SVT termination medication without any significant increase in adverse events or time spent in the emergency department. Interpretation: The MVM is more effective than the SVT in terminating SVT. This should encourage broader adoption of the MVM as a first-line vagal manoeuvere in subjects presenting with SVT in the emergency room. Funding Statement: There was no funding source for this study. Declaration of Interests: We declare no competing interests.

Initial and Sustained Response Effects of 3 Vagal Maneuvers in Supraventricular Tachycardia: A Randomized, Clinical Trial.

For acute termination of supraventricular tachycardia (SVT), vagal maneuvers, including the standard Valsalva maneuver (sVM), modified Valsalva (mVM) maneuver, and carotid sinus massage (CSM), are first-line interventions. There is no criterion standard technique. This prospective, randomized study was aimed at analyzing the success rates of these 3 vagal maneuvers as measured by sustaining sinus rhythm at the fifth minute and SVT termination. We conducted this prospective, randomized controlled study in an emergency department (ED). We enrolled all the patients who were admitted to the ED and diagnosed with SVT. We randomly assigned them to 3 groups receiving sVM, mVM, and CSM and recorded the patients' responses to the vagal maneuvers and SVT recurrence after vagal maneuvers. The study was completed with 98 patients. A total of 25 (25.5%) instances of SVT were initially treated successfully with vagal maneuvers. The success rate was 43.7% (14/32 cases) from mVM, 24.2% (8/33) for sVM, and 9.1 % (3/33) for CSM (p<0.05). At the end of the fifth minute, only 12.2% (12/98) of all patients had sinus rhythm. Sinus rhythm persisted in 28.1% (9/32) of patients in the mVM group, 6.1% (2/33) of patients in the sVM group, and 3% (1/33) in the CSM group at the fifth minute (p<0.05). mVM is superior to the CSM maneuver in terminating SVT and maintaining rhythm. We conclude that it is beneficial to use mVM, which is more effective and lacks side effects.

When and howdoes a single ventricular premature beat initiate and terminate supraventricular tachycardia?

The differential diagnosis of a supraventricular tachycardia (SVT) is accomplished using a number of pacing maneuvers. The incidence and mechanism of a single ventricular premature beat (VPB) on initiation and termination of tachycardia were evaluated during programmed electrical stimulation (PES) of the heart in patients with the two most common regular SVTs: atrioventricular re-entrant tachycardia (AVNRT) and orthodromic atrioventricular tachycardia (AVRT). Three hundred and thirty-seven consecutive patients aged above 18years with an inducible sustained AVNRT or AVRT were prospectively enrolled. Patients with more than one tachyarrhythmia mechanism were excluded. Two hundred and seventeen patients (64.4%) had typical slow/fast AVNRT and 120 (35.6%) had an orthodromic AVRT using a rapidly conducting accessory pathway for V-A conduction. In this cross-sectional study, we specifically report the analysis of tachycardia induction and termination by a single VPB. Tachycardia induction with a single VPB during sinus rhythm was seen in 7 of 120 AVRT and in only one of the 217 patients with AVNRT, (5.8% vs. 0.3%, p<0.05). When a single VPB was delivered during basic ventricular pacing these values were 28% versus 4%, respectively, (p<0.001). Termination of tachycardia by a single VPB was observed in nine (4.1%) patients with AVNRT and in 57 (47.5%) with AVRT (p<0.001). Initiation of SVT by a single VPB during sinus rhythm was uncommon and favored AVRT. Termination of SVT by a single VPB was commonly seen in AVRT but rarely in AVNRT. These findings can be of help when interpreting a noninvasive arrhythmia event recording.

Etripamil Nasal Spray for Rapid Conversion of Supraventricular Tachycardia to Sinus Rhythm

BackgroundThere is no nonparenteral medication for the rapid termination of paroxysmal supraventricular tachycardia. ObjectivesThe purpose of this study was to assess the efficacy and safety of etripamil nasal spray, a short-acting calcium-channel blocker, for the rapid termination of paroxysmal supraventricular tachycardia (SVT). MethodsThis phase 2 study was performed during electrophysiological testing in patients with previously documented SVT who were induced into SVT prior to undergoing a catheter ablation. Patients in sustained SVT for 5 min received either placebo or 1 of 4 doses of active compound. The primary endpoint was the SVT conversion rate within 15 min of study drug administration. Secondary endpoints included time to conversion and adverse events. ResultsOne hundred four patients were dosed. Conversion rates from SVT to sinus rhythm were between 65% and 95% in the etripamil nasal spray groups and 35% in the placebo group; the differences were statistically significant (Pearson chi-square test) in the 3 highest active compound dose groups versus placebo. In patients who converted, the median time to conversion with etripamil was <3 min. Adverse events were mostly related to the intranasal route of administration or local irritation. Reductions in blood pressure occurred predominantly in the highest etripamil dose. ConclusionsEtripamil nasal spray rapidly terminated induced SVT with a high conversion rate. The safety and efficacy results of this study provide guidance for etripamil dose selection for future studies involving self-administration of this new intranasal calcium-channel blocker in a real-world setting for the termination of SVT. (Efficacy and Safety of Intranasal MSP-2017 [Etripamil] for the Conversion of PSVT to Sinus Rhythm [NODE-1]; NCT02296190)

An analysis of clinical characteristics and acute treatment of supraventricular tachycardia in children from a multicenter study

Objective: The study assessed the clinical characteristics and response to acute intravenous antiarrhythmic drug therapy of supraventricular tachycardia (SVT) in children. Methods: This was a multicenter prospective descriptive study including 257 children from First Hospital of Tsinghua University, Peking University First Hospital, Children's Hospital Affiliated to Capital Institute of Pediatrics and Beijing Anzhen Hospital who received intravenous antiarrhythmic drug therapy for SVT from July 2014 to February 2017. The clinical and tachycardia features, response to intravenous antiarrhythmic drug therapy of these children were characterized. Statistical analyses were performed using t test, Mann-Whitney U test, χ(2) test and H test. Results: The onset of SVT occurred at any age with a distribution with positive skewness, 57.6% (n=148) children<1 year, 17.5% (n=45) children1~<3 years, 10.5% (n=27) children 3~<6 years and 14.4% (n=37) children ≥ 6 years of age. The percentages of SVT types were 49.4% (n=127) for atrioventricular reentry tachycardia (AVRT), 4.3% (n=11) for atrioventricular nodal reentry tachycardia (AVNRT), 26.8% (n=69) for unclassified paroxysmal SVT and 19.5% (n=50) for atrial tachycardia (AT), respectively. Tachycardia-induced cardionyopathy (TIC) secondary to SVT developed in 30 of 225 (13.3%). Left ventricular ejection fraction (LVEF) of the 27 children attacked by TIC returned to normal after successful control of SVT (41.1%±6.3% vs. 60.3%±9.2%, t=-10.397, P=0.000). Complete termination of SVT by antiarrhythmic drugs was achieved in 164 of 257 (63.8%), partial termination rate was 18.7% (48 of 257) and failure to terminate rate was 17.5% (45 of 257). Propafenone (complete cardioversion in 98 (73.1%) of 134) and amiodarone (complete cardioversion in 23 (76.7%) of 30) showed better efficacy for SVT termination than adenosine (complete cardioversion in 26 (44.1%) 59) (χ(2)=20.524, P=0.000). Paroxysmal SVT had a higher termination rate on pharmacological therapy than AT (67.1% vs. 50.0%, χ(2)=6.337, P=0.042). Patients of different age groups had significantly different response to antiarrhythmic therapy (χ(2)=13.904, P=0.031). Children<1 year of age showed the least response to antiarrhythmic drug therapy with complete termination in 51 (55.4%) of 92. Adverse effects occurred in 9 patients (3.5%): Four patients had severe hypotensive shock using propafenone (n=3) and adenosine (n=1), and 3 patients had sinus arrest using adenosine. Conclusion: Most (57.6%) children with SVT have their first clinical episode within 1 year of age, and AVRT is the most common type. TIC occurs in 13.3% of children with SVT. Intravenous antiarrhythmic drug therapy has a 63.8% complete termination rate for children with SVT and incidence of adverse effects is 3.5%. Propafenone and amiodarone are more effective for SVT termination in children than adenosine. Serious adverse effects may occur when using propafenone.

Adenosine induced ventricular fibrillation in a structurally normal heart: a case report

BackgroundAdenosine is the first-line pharmacotherapy for termination of supraventricular tachycardia through its action on the atrioventricular node. However, pro-arrhythmic effects of adenosine are also recognised, most notably in the presence of pre-excited atrial fibrillation. In this case report, we describe the induction of ventricular fibrillation in a patient with no demonstrable accessory pathway, nor any other structural heart disease. This rare, idiosyncratic reaction has never previously been reported and is of relevance given the widespread and routine use of adenosine in clinical practice.Case presentationA 26-year-old woman of Cypriot origin presented to our emergency department with a sudden onset of palpitations and chest discomfort. She was healthy, with no previous medical history and no regular medications. An electrocardiogram demonstrated a narrow complex tachycardia with a rate of 194 beats per minute. Following failure of vagal maneuvers to terminate the tachycardia, the assessing physician administered a single intravenous dose of 6 mg adenosine. Our patient instantaneously developed coarse ventricular fibrillation and circulatory collapse. Cardiopulmonary resuscitation was initiated and our patient was rapidly defibrillated to sinus rhythm with a single 150 J direct current shock. A 900-mg loading dose of intravenous amiodarone was commenced and our patient was managed in the cardiac high dependency unit. No further arrhythmias were identified on continuous cardiac monitoring.On review, her presenting electrocardiogram had demonstrated rapidly conducted atrial fibrillation with no evidence of ventricular pre-excitation. Concordantly, her resting electrocardiogram was not suggestive of any accessory pathway. This was conclusively excluded on invasive electrophysiology study, with negative programmed ventricular stimulation up to three extrastimuli. Extensive laboratory investigations were unremarkable and failed to identify an underlying cause for her episode of atrial fibrillation. Furthermore, cardiac magnetic resonance imaging demonstrated a structurally normal heart, with no edema, fibrosis or infarction as well as normal coronary artery anatomy.ConclusionsAdenosine remains a safe and highly efficacious therapy for supraventricular tachycardia. However, this unusual case demonstrates the ability of adenosine to induce circulatory collapse and reminds the clinician that prompt access to resuscitation, defibrillation, and transcutaneous pacing equipment is mandatory with every administration of this drug.

Validation of right ventricular pacing response during supraventricular tachycardia in mechanistic diagnosis (transition zone)

Background Right ventricular pacing (RVP) during supraventricular tachycardia (SVT) produces progressive QRS fusion before the QRS morphology becomes stable. This transition zone (TZ) may provide useful information for differentiating orthodromic reciprocating tachycardia (ORT) from atrioventricular nodal re-entrant tachycardia and atrial tachycardia independent of entrainment success. Methods and results We studied the effect of properly timed RVP on atrial timing during the TZ in 63 patients with SVT who had RVP within 40 ms of the tachycardia cycle length. The TZ during RVP includes progressively fused QRS complexes and the first paced complex with a stable QRS morphology based on analysis of the 12-lead ECG. We also measured the stimulus–atrial (SA) interval from the end of the TZ and with each QRS complex thereafter until pacing was terminated or ventriculoatrial block occurred. A fixed SA interval was defined as variation less than or equal to 10 ms during RVP. Atrial pre-excitation, postexcitation, or SVT termination with abrupt ventriculoatrial block was observed within the TZ in 19 of 22 patients with ORT. A fixed SA interval was established within the TZ in 22 of 22 patients with ORT. At least one of these two responses was observed in all patients with ORT. Only four patients out of 36 with atrioventricular nodal re-entrant tachycardia showed atrial pre-excitation within TZ and only four patients showed fixed SA within TZ. None of the atrial tachycardia patients had atrial timing perturbed or a fixed SA interval established within the TZ. Conclusion During RVP within 40 ms of the tachycardia cycle length, ORT is the likely mechanism when atrial timing is perturbed or a fixed SA interval is established within the TZ.

The type of spontaneous termination of supraventricular tachycardia: What does it tell us?

The type of spontaneous termination of supraventricular tachycardia: What does it tell us?

Reconsidering the effectiveness and safety of carotid sinus massage as a therapeutic intervention in patients with supraventricular tachycardia

ObjectiveThe objectives of our investigation were to review the evidence for the efficacy and safety of carotid sinus massage in terminating supraventricular tachycardia and to determine if other potentially less harmful interventions have been established to be safer and more effective. MethodsA search using PubMed, Ovid, and COCHRANE databases was performed using the terms supraventricular tachycardia, carotid sinus massage, SVT, and CSM. Articles not written in English were excluded. There was a paucity of randomized controlled trials comparing various supraventricular tachycardia (SVT) interventions. However, articles of highest quality were selected for review and inclusion. In addition, articles examining potential hazards of carotid sinus massage in case report format were reviewed, even when performed for other indications other than SVT, as the maneuver is identically performed. Selected articles were reviewed by both authors for relevance to the topic. ResultsSummarizing the findings of this review leads to these 3 fundamental conclusions. First, a therapeutic intervention should only be performed when the benefit of the procedure outweighs its risk. Carotid sinus massage exposes the patient to rare but potentially devastating iatrogenic harm. Second, a therapeutic intervention should be efficacious. The efficacy of carotid sinus massage in terminating supraventricular tachycardia appears to be modest at best. Third, other readily available, easily mastered, and potentially safer and more efficacious alternative interventions are available such as Valsalva maneuver and pharmacologic therapy. ConclusionBased on the limited evidence available, we believe that carotid sinus massage should be reconsidered as a first-line therapeutic intervention in the termination of SVT.

Effectiveness of the Valsalva Manoeuvre for reversion of supraventricular tachycardia.

People with the cardiac arrhythmia supraventricular tachycardia (SVT) frequently present to clinicians in the prehospital and emergency medicine settings. Restoring sinus rhythm by terminating the SVT involves increasing the refractoriness of atrioventricular nodal tissue within the myocardium by means of vagal manoeuvres, pharmacological agents, or electrical cardioversion. A commonly used first-line technique to restore the normal sinus rhythm (reversion) is the Valsalva Manoeuvre (VM). This is a non-invasive means of increasing myocardial refractoriness by increasing intrathoracic pressure for a brief period, thus stimulating baroreceptor activity in the aortic arch and carotid bodies, resulting in increased parasympathetic (vagus nerve) tone. To assess the evidence of effectiveness of the VM in terminating SVT. We updated the electronic searches of the Cochrane Central Register of Controlled Trials (CENTRAL; 2014, Issue 7); MEDLINE Ovid (1946 to August week 3, 2014); EMBASE Classic and EMBASE Ovid (1947 to 27 August 2014); Web of Science (1970 to 27 August 2014); and BIOSIS Previews (1969 to 22 August 2014). We also checked trials registries, the Index to Theses, and the bibliographies of all relevant publications identified by these strategies. We included all randomised controlled trials (RCTs) that examined the effectiveness of VM in terminating SVT. Two review authors independently extracted the data using a standardised form. We assessed each trial for internal validity, resolving any differences by discussion. We then extracted and entered data into Review Manager 5. In this update, we did not identify any new RCT studies for inclusion. We identified two RCT studies as ongoing that we are likely to include in future updates. Accordingly, our results are unchanged and include three RCTs with a total of 316 participants. All three studies compared the effectiveness of VM in reverting SVT with that of other vagal manoeuvres in a cross-over design. Two studies induced SVT within a controlled laboratory environment. Participants had ceased all medications prior to engaging in these studies. The third study reported on people presenting to a hospital emergency department with an episode of SVT. These participants were not controlled for medications or other factors prior to intervention.The two laboratory studies demonstrated reversion rates of 45.9% and 54.3%, whilst the clinical study demonstrated reversion success of 19.4%. This discrepancy may be due to methodological differences between studies, the effect of induced SVT versus spontaneous episodic SVT, and participant factors such as medications and comorbidities. We were unable to assess any of these factors, or adverse effects, further, since they were either not described in enough detail or not reported at all.Statistical pooling was not possible due to heterogeneity between the included studies. We did not find sufficient evidence to support or refute the effectiveness of VM for termination of SVT. Further research is needed, and this research should include a standardised approach to performance technique and methodology.

Supraventricular tachycardia termination after atrial noncapture: What is the mechanism?

A 63-year-old man with a history of palpitations presented for electrophysiology study. Multipolar catheters were placed in the right atrium, His bundle region, right ventricle, and coronary sinus (CS), with the proximal CS electrode positioned at the CS ostium. Normal atrial-His and His-ventricular intervals were recorded during sinus rhythm.

Prehospital Synchronized Electrical Cardioversion of a Poorly Perfused SVT Patient by Paramedics

Synchronized Direct Current Cardioversion (SDC) is an established therapy for the termination of supraventricular tachycardia (SVT - either atrio-ventricular nodal reentry tachycardia (AVNRT) or atrio-ventricular reentrant tachycardia (AVRT)) with poor perfusion. The evidence is extremely limited with regard to the safety and effectiveness of this therapy. In Australia, half of the eight ambulance services include SDC within their clinical practice guidelines for the management of poorly perfused SVT; however the degree of variation in the application of SDC across these guidelines suggests a need to quantify the practice. This case provides a previously unreported example of the safety and effectiveness of prehospital SDC for SVT (with poor perfusion precipitated by a Valsalva Maneuver) by Victorian paramedics, and discusses the available literature regarding the effectiveness and safety of this practice.

Effects of deep sedation on cardiac electrophysiology in patients undergoing radiofrequency ablation of supraventricular tachycardia: impact of propofol and ketamine

Propofol is commonly used as an anaesthetic during catheter ablation. Bradycardia and termination of supraventricular tachycardia (SVT) under propofol are reported. Ketamine is used for cardiac catheterization procedures and increases heart rate and blood pressure. Our study aimed to determine the effects of propopfol and ketamine on atrial electrophysiology. Thirty-one patients undergoing electrophysiological study prior to SVT ablation were enrolled. Patients received a combination of propofol/midazolam (n = 10), ketamine/midazolam (n = 9), or midazolam alone (n = 12). Electrophysiological study was performed before and after administration of the anaesthetic agents. Blood pressure, corrected sinus node recovery time, Wenckebach cycle length, and atrial conduction time were measured. We found a significant increase in heart rate, systolic, and diastolic blood pressure and a significant shortening of atrial conduction time after administration of ketamine compared with propofol and the control. Results for ketamine, propofol and the control, respectively: mean (SD) change in heart rate was 12.4 (8.3), -1.4 (8), and 1 (7.5) b.p.m. (P = 0.002); mean (SD) change in systolic blood pressure was 19.2 (8.1), -22 (9), and 0.1 (5.7) mmHg (P < 0.001); mean (SD) change in diastolic blood pressure was 6.6 (9.7), -7.8 (2.9), and 2.3 (4.5) mmHg (P = 0.001); and mean (SD) change in atrial conduction time was -13.7 (16.4), 4.5 (11.1), and -0.3 (3.8) ms (P = 0.008). No significant affection of sinus node or antrioventricular node function was seen. Our results show stimulatory effects of ketamine on heart rate, atrial conduction, and blood pressure. Ketamine, therefore, may be beneficial in patients with pre-existing hypotension and bradycardia.

New frontiers of supraventricular tachycardia and atrial flutter evaluation and catheter ablation

Radiofrequency catheter ablation (RFCA) has revolutionized treatment for tachyarrhythmias and has become first-line therapy for some tachycardias. Although developed in the 1980s and widely applied in the 1990s, the technique is still in development. Transesophageal atrial pacing (TAP) can used for initiation and termination of supraventricular tachycardia (SVT). Methods: The paroxysmal SVT include a wide spectrum of disorders including, in descending order of frequency, atrial flutter, atrioventricular (AV) nodal reentry, Wolff-Parkinson-White syndrome, and atrial tachycardia. While not lifethreatening in most cases, they may cause important symptoms, such as palpitations, chest discomfort, breathlessness, anxiety, and syncope, which significantly impair quality of life. Medical therapy has variable efficacy, and most patients are not rendered free of symptoms. Research over the past several decades has revealed fundamental mechanisms involved in the initiation and maintenance of all of these arrhythmias. Knowledge of mechanisms has in turn led to highly effective surgical and catheter-based treatments. The supraventricular arrhythmias and their treatment are de-scribed in this report. SVT initiation was analysed with programmed TAP in 49 patients with palpitations (age 47 ± 17 years, 24 females, 25 males). Results: In comparison to antiarrhythmic drug therapy the radiofrequency catheter ablation in patients suffering from atrial flutter, atrioventricular nodal reentry, atrioventricular reentry and atrial tachycardia is the better choice in most cases. TAP SVT initiation was possible in 23 patients before RFCA. Atrial cycle length of SVT was 320 ± 59 ms. We initiated AV nodal reentrant tachycardia (AVNRT, n=15), atrial tachycardia (AT, n=6) and AV reentrant tachycardia with Kent pathway conduction (AVRT, n=2) before RFCA. Conclusions: Radiofrequency catheter ablation is a successful and safe method to cure most patients with paroxysmal supraventricular tachycardias. TAP allowed initiation and termination of SVT especially in outpatients.

Choice and Utility of Pacing Maneuver in Establishing the Mechanism of Supraventricular Tachycardia: A Single Center Experience.

BackgroundTo evaluate the choice and utility of pacing maneuvers in the electrophysiology (EP) laboratory in establishing supraventricular tachycardia (SVT) mechanism.MethodsWe retrospectively examined a cohort of 160 consecutive patients with SVT presenting for invasive EP evaluation to a single center with 8 electrophysiologists. We analyzed the utility of the two most commonly used pacing maneuvers: (1) ventricular entrainment (VE) and (2) His-refractory premature ventricular stimuli (HRPVC) during SVT.ResultsVE was performed in 96 patients: atrial tachycardia (AT) 12, atrioventricular nodal reentrant tachycardia (AVNRT) 66, and orthodromic reciprocating tachycardia (ORT) 18. During VE, AT patients were most likely to have ventriculo-atrial (VA) dissociation (AT 58%, AVNRT 18%, ORT 0%, P < 0.001) and had a tendency towards less SVT termination (AT 0%, AVNRT 9%, ORT 11%, P = 0.19). HRPVCs were delivered in 39 patients: AT 1, AVNRT 24, and ORT 14. Advancement of atrial signal with HRPVC was only observed in ORT (AT 0%, AVNRT 0%, ORT 79%, P < 0.001) and SVT termination was also mostly observed in ORT (AT 0%, AVNRT 4%, ORT 21%, P = 0.33). The overall diagnostic utility of VE was lowest in AT (AT 42%, AVNRT 71%, ORT 83%, P = 0.04), while HRPVC was rarely used in AT. Furthermore, the utilization of maneuvers varied extensively (0% to100%) among the 8 electrophysiologists.ConclusionThere is great variation in the utilization of pacing maneuvers and their utility in ascertaining the mechanism of SVT. Our results support the fact that discerning AT from AVNRT mechanism remains the most challenging task in SVT diagnosis.

New Criteria During Right Ventricular Pacing to Determine the Mechanism of Supraventricular Tachycardia

Right ventricular pacing (RVP) during supraventricular tachycardia produces progressive QRS fusion before the QRS morphology becomes stable. This transition zone (TZ) may provide useful information for differentiating orthodromic reciprocating tachycardia (ORT) from atrioventricular nodal reentrant tachycardia and atrial tachycardia independent of entrainment success. We studied the effect of properly timed RVP on atrial timing during the TZ in 92 patients with supraventricular tachycardia who had RVP within 40 ms of the tachycardia cycle length. The TZ during RVP includes progressively fused QRS complexes and the first paced complex with a stable QRS morphology based on analysis of the 12-lead ECG. We also measured the stimulus-atrial interval from the end of the TZ and with each QRS complex thereafter until pacing was terminated or ventriculo-atrial block occurred. A fixed stimulus-atrial interval was defined as variation <10 ms during RVP. Atrial preexcitation, postexcitation, or supraventricular tachycardia termination with abrupt ventriculo-atrial block was observed within the TZ in 32 of 34 patients with ORT. A fixed stimulus-atrial interval was established within the TZ in 33 of 34 patients with ORT. At least 1 of these 2 responses was observed in all patients with ORT. None of the patients with atrioventricular nodal reentrant tachycardia or atrial tachycardia had atrial timing perturbed or a fixed stimulus-atrial interval established within the TZ. During RVP within 40 ms of the tachycardia cycle length, ORT is the likely mechanism when atrial timing is perturbed or a fixed stimulus-atrial interval is established within the TZ.