Spontaneous Supraventricular Tachycardia Research Articles

Nose-to-Heart Approach: Unveiling an Alternative Route of Acute Treatment.

Intranasal (IN) administration has emerged as a novel approach for rapid systemic absorption, with potential applicability in the management of acute cardiovascular events. This review explores the evolution of IN cardiovascular pharmacotherapy, emphasizing its potential in achieving systemic effects and bypassing the first-pass metabolism associated with oral administration. The extensive vascularization of nasal mucosa and a porous endothelial basement membrane facilitate efficient drug absorption into the bloodstream. The IN route ensures a critical swift onset of action, which allows self-administration in at-home settings. For instance, etripamil nasal spray, a first-in-class formulation, exemplifies the therapeutic potential of this approach in the treatment of spontaneous supraventricular tachycardia. The review critically assesses studies on IN formulations for angina, acute myocardial infarction, hypertensive episodes, and cardiac arrhythmias. Preclinical evaluations of beta-blockers, calcium-channel blockers, and antianginal drugs demonstrate the feasibility of IN administration for acute cardiovascular events. A small number of clinical trials have revealed promising results, emphasizing the superiority of IN drug delivery over oral administration in terms of bioavailability and onset of action. Unambiguously, the limited clinical trials and patient enrollment pose challenges in generalizing experimental outcomes. However, the nose-to-heart approach has clinical potential.

Postnatal recurrence and transesophageal inducibility of prenatally treated fetal supraventricular tachycardia.

Antiarrhythmic treatment of fetal supraventricular tachycardia (SVT) is used to prevent morbidity and mortality. The postnatal management of survivors is often arbitrary and varied. The purpose of this study was to examine the utility of a risk-based postnatal management strategy. Sixty-six prenatally treated newborns with fetal long or short ventriculoatrial tachycardia were reviewed. Postnatal diagnoses included atrioventricular reentrant tachycardia, atrial ectopic tachycardia, and permanent junctional reciprocating tachycardia. Unless SVT persisted to birth, early neonatal observation without treatment was recommended. For newborns without spontaneous arrhythmia after ≥2 days of observation, inducibility was tested by transesophageal pacing study (TEPS). Postnatal therapy was advised for spontaneous or inducible SVT. Characteristics associated with these outcomes were analyzed. Twenty-eight patients (42%) experienced SVT at or early after birth, which was associated with fetal long ventriculoatrial tachycardia (odds ratio [OR] 6.8; 95% confidence interval [CI] 1.88-24.57; P = .0029); delayed in utero cardioversion with treatment (median 11 days vs 5.5 days; P < .0001); prenatal treatment with multiple antiarrhythmics (OR 4.42; 95% CI 1.56-12.55; P = .0059); and postnatal atrial ectopic tachycardia/permanent junctional reciprocating (OR 18.0; 95% CI 2.11-153.9; P = .0013). Of the 38 neonates undergoing TEPS, 19 (50%) had inducible tachyarrhythmias. Recurrence of SVT during infancy or childhood was documented in 4 of 6 patients with SVT at birth (66%), 8 of 22 patients with early neonatal SVT (36%), 4 of 19 patients with inducible SVT (21%), and 0 of 19 untreated patients without inducible SVT (0%) (P= .0032). The postnatal risk of SVT is related to the arrhythmia mechanism and prenatal treatment response. In newborns without spontaneous SVT, TEPS may be useful to guide the need for postnatal treatment on the basis of SVT inducibility.

The Effectiveness of Adenosine in Treating the Acute Attacks of Supra-ventricular Tachycardia

Background: Adenosine is a natural adenine nucleoside available endogenously that decreases heart beat by blocking atrioventricular (AV) node transiently so that extend the duration of conduction in (AV) node when injected intravenously. It has a curative value in the conversion of majority of supraventricular tachycardia (SVT) to sinus rhythm. In order to evaluate the adenosine in the management of arrhythmias we conduct this study. Objective: This study was conducted to evaluate the safety and efficacy of intravenous adenosine therapy for treatment of (SVT), to determine the optimal adenosine dose effective in (SVT), and to determine the underlying conditions affecting the effective dose. And to evaluate the effectiveness of vagal maneuvers in terminating of spontaneous SVT patients and methods: A cross-sectional study conducts in a group consist of 69 patients ranged from 23-70 years old admitted to the Coronary care unit in Azadi Teaching Hospital ,in Kirkuk city, from July 2014 to June 2016. The diagnosis of (SVT) was made by present of tachycardia which is of narrow complex with a heart beat rate greater than 140 beats/ min by 12 leads chest electrocardiography (ECG). In patients who are hemodynamically stable, vagal maneuvers were carried out initially in the form of carotid sinus massage, gag reflex and Valsalva maneuver, if this failed intravenous administration of adenosine as recommended doses were preformed. If three doses of adenosine boluses were unsuccessful to convert the arrhythmia, patients were managed with other available antiarrythmias or managed with direct electrical cardio version (DC). In unstable patients were managed with (DC). Results: Of 69 included patients, diagnosed as (SVT), M: F ratio was 1:2.1. Their age ranged from 23 years to 70 years with mean age of 57 years. Vagal maneuvers (VM) resulted in restoration of sinus rhythm (SR) in 8patients (7.6%). Out of 57 episodes of (SVT), Adenosine was effective in reverting 51 episodes of SVT to sinus rhythm (89.5%). Of those converted, 18 required a single dose (6mg) (31.6%), fifteen required one additional (12mg) dose (26.3%), and another 18 required two additional doses (81mg) (31.6%).four patients were hemo-dynamically unstable (systolic blood pressure <90 mm Hg) which required (DC). Six patients (10.5%) not responding to full adenosine dose(81mg), started treatment with other medication, 1 with verapamil, 4 with amiodarone, and1 with digoxin. All of them were successfully treated. Conclusions: Adenosine is an effective medicine in treating (SVT) in those patients in whom vagal maneuvers has unsuccessful. It demonstrates a high rate of success in terminating acute attack of SVT. A higher dose may be required in majority of patients specially

Major publications in the critical care pharmacotherapy literature in 2015.

Recently published practice guidelines and research reports on pharmacotherapy in critical care patient populations are summarized. The Critical Care Pharmacotherapy Literature Update (CCPLU) Group is composed of over 50 experienced critical care pharmacists who evaluate 31 peer-reviewed journals monthly to identify literature pertaining to pharmacotherapy in critical care populations. Articles are chosen for summarization in a monthly CCPLU Group publication on the basis of applicability and relevance to clinical practice and strength of study design. From January to December 2015, a total of 121 articles were summarized; of these, 3 articles presenting clinical practice guidelines and 12 articles presenting original research findings were objectively selected for inclusion in this review based on their potential to change or reinforce current evidence-based practice. The reviewed guidelines address the management of intracranial hemorrhage (ICH), adult advanced cardiac life support (ACLS) and post-cardiac arrest care, and the management of supraventricular tachycardia (SVT). The reviewed research reports address topics such as nutrition in critically ill adults, administration of β-lactams for severe sepsis, anticoagulant selection in the context of continuous renal replacement therapy, early goal-directed therapy in septic shock, magnesium use for neuroprotection in acute stroke, and progesterone use in patients with traumatic brain injury. Important recent additions to the critical care pharmacy literature include updated joint clinical practice guidelines on the management of spontaneous ICH, ACLS, and 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.

347 Is electrophysiological study required in children with spontaneous supraventricular tachycardia and normal ECG in sinus rhythm?

347 Is electrophysiological study required in children with spontaneous supraventricular tachycardia and normal ECG in sinus rhythm?

Intracardiac Electrogram T-Wave Alternans/Variability Increases Before Spontaneous Ventricular Tachyarrhythmias in Implantable Cardioverter-Defibrillator Patients

T-wave alternans (TWA) increases before ventricular tachycardia (VT) or fibrillation (VF), suggesting that it may warn of VT/VF in implantable cardioverter-defibrillator patients. Recently, we described a method for measuring alternans and nonalternans variability (TWA/V) from electrograms (EGMs) stored in implantable cardioverter-defibrillators before VT/VF. The goal of this prospective, multicenter study was to determine whether EGM TWA/V was greater before VT/VF than at baseline. We enrolled 63 implantable cardioverter-defibrillator patients. TWA/V was computed from stored EGMs before spontaneous VT/VF and from sequential windows of 8 pairs of beats using 4 different control recordings: baseline rhythm, rapid pacing at 105 bpm, segments of ambulatory Holter EGMs matched to the time of VT/VF episodes, and EGMs before spontaneous supraventricular tachycardia. During follow-up, 28 patients had 166 episodes of VT/VF. TWA/V was greater before VT/VF (62.9 ± 3.1 μV; n = 28) than during baseline rhythm (12.8 ± 1.8 μV; P < 0.0001; n = 62), during rapid pacing (14.5 ± 2.0 μV; P < 0.0001; n = 52), before supraventricular tachycardia (27.5 ± 6.1 μV; P < 0.0001; n = 9), or during time-matched ambulatory controls (12.3 ± 3.5 μV; P < 0.0001; n = 16). By logistic regression, the odds of VT/VF increased by a factor of 2.2 for each 10-μV increment in TWA/V (P < 0.0001). In implantable cardioverter-defibrillator patients, EGM TWA/V is greater before spontaneous VT/VF than in control recordings. Future implantable cardioverter-defibrillators that measure EGM TWA/V continuously may warn patients and initiate pacing therapies to prevent VT/VF.

Slow infusion of calcium channel blockers compared with intravenous adenosine in the emergency treatment of supraventricular tachycardia

IntroductionThe emergency treatment of supraventricular tachycardia (SVT) has, over the last two decades, changed from verapamil to adenosine primarily owing to documented hypotensive episodes occurring with rapid bolus infusions of the calcium channel blocker. Slow infusions of calcium channel blockers have not previously demonstrated hypotension to any significant degree. The aim of this study was to compare the efficacy and safety of bolus intravenous adenosine and slow infusion of the calcium channel blockers verapamil and diltiazem in the emergency treatment of spontaneous SVT. MethodsA prospective randomized controlled trial with one group receiving bolus intravenous adenosine 6mg followed, if conversion was not achieved, by adenosine 12mg; and the other group receiving a slow infusion of either verapamil at a rate of 1mg per minute up to a maximum dose of 20mg, or diltiazem at a rate of 2.5mg per minute up to a maximum dose of 50mg. These infusions would be stopped at time of conversion of the SVT or when the whole dose was administered. Heart rate and blood pressure was continuously monitored during drug infusion and for up to 2h post-conversion. ResultsA total of 206 patients with spontaneous SVT were analysed. Of these, 102 were administered calcium channel blockers (verapamil=48, diltiazem=54) and 104 were given adenosine. The conversion rates for the calcium channel blockers (98%) were statistically higher than the adenosine group (86.5%), p=0.002, RR 1.13, 95% CI 1.04–1.23. The initial mean change in blood pressure post-conversion in the calcium channel blocker group was −13.0/−8.1mmHg (verapamil) and −7.0/−9.4mmHg (diltiazem) and 2.6/−1.7mmHg for adenosine. Only one patient in the calcium channel group (0.98%) (95% CI 0.025–5.3) developed hypotension, and none in the adenosine group. ConclusionSlow infusion of calcium channel blockers is an alternative to adenosine in the emergency treatment of stable patients with SVT. Calcium channel blockers are safe and affordable for healthcare systems where the availability of adenosine is limited.

The QRS configuration during bundle branch block. What has rate got to do with it?

Bundle branch block is a common cause of a widened QRS complex, and, as indicated in Table 1 , different mechanisms may be responsible. Three are rate related and one is based upon retrograde invasion into the bundle branch. Those four mechanisms lead to the intermittent appearance of a bundle branch block pattern.1 View this table: Table 1 Types and mechanisms of bundle branch (BB) block Most commonly, bundle branch block is continuously present, so-called fixed bundle branch block, the patient showing a wide QRS all the time independent of the heart rate. When the heart rate is fast and the QRS wide, the challenge for the cardiologist is to differentiate bundle branch block from other causes such as ventricular pre-excitation, the use of class IC drugs leading to rate-related QRS widening, and in particular ventricular tachycardia. Datino et al. 2 describe QRS behaviour during incremental atrial pacing in 59 patients with fixed bundle branch block. In 14 of them they could also look at the QRS configuration during spontaneous supraventricular tachycardia. The question they wanted to answer was: ‘Does the bundle branch block pattern stays the same during rapid ventricular rates or do changes occur possibly leading to the incorrect diagnosis of a ventricular tachycardia?’ That is an important question because most cardiologists believe that in the patient with fixed bundle branch block the QRS does not change when the heart rate accelerates. Datino et al. 2 show that during pacing of the atrium … *Corresponding author. Tel: +31 433215440, Fax: +31 43 3261903, Email: hwellens{at}xs4all.nl

Clinical Results of an Advanced SVT Detection Enhancement Algorithm

Supraventricular tachycardia (SVT) has many characteristics that are similar to ventricular tachycardia (VT). This presents a significant challenge for the SVT-detection algorithms of an implantable cardioverter defibrillator (ICD). A newly developed ICD, which utilizes a Vector Timing and Correlation algorithm as well as interval-based conventional SVT discrimination algorithms (Rhythm ID), was evaluated in this study. This study was a prospective, multicenter trial that evaluated 96 patients implanted with an ICD at 21 U.S. centers. All patients were followed at 2 weeks, 1 month, and every 3 months post implant. A manual Rhythm ID reference vector was acquired prior to any arrhythmia induction. During testing, atrial tachyarrhythmias were induced first, followed by ventricular arrhythmia induction. Induced and spontaneous SVT and VT/ventricular fibrillation (VF) episodes recorded during the trial were annotated by physician investigators. The mean age of the patients implanted with an ICD was 67.3 +/- 10.8 years. Eighty-one percent of patients were male. The primary cardiovascular disease was coronary artery disease, and the primary tachyarrhythmia was monomorphic VT. Implementation of the Rhythm ID algorithm did not affect the VT/VF detection time. There were a total of 370 ventricular tachyarrhythmias (277 induced and 93 spontaneous) and 441 SVT episodes (168 induced and 273 spontaneous). Sensitivity for ventricular tachyarrhythmias was 100%, and specificity for SVT was 92% (94% and 91% for induced and spontaneous SVT, respectively). All patients had a successful manual Rhythm ID acquisition prior to atrial tachyarrhythmia induction. At the 1-month follow-up, the Rhythm ID references were updated automatically an average of 167.8 +/- 122.7 times. Stored Rhythm ID references correlated to patients' normally conducted rhythm 100% at 2 weeks, and 98% at 1 month. The Rhythm ID algorithm achieved 100% sensitivity for VT/VF, and 92% specificity for SVT. The manual and automatic Rhythm ID update algorithms successfully acquired references, and the updated references were highly accurate.

Slow-infusion of calcium channel blockers in the emergency management of supraventricular tachycardia

Objective: To compare the efficacy of verapamil and diltiazem as slow infusions in terminating spontaneous supraventricular tachycardia (SVT) in the emergency department (ED). Method: Patients of at least 10 years of age who presented to our ED with regular narrow complex tachycardia not converted with a vagal manoeuvre with an ECG diagnosis of SVT were included. Those who were haemodynamically unstable were excluded. Patients were randomized to undergo either verapamil infusion at a rate of 1 mg/min to a maximum of 20 mg or diltiazem infusion at a rate of 2.5 mg/min to a maximum of 50 mg. Results: Eighty-one patients were randomized to receive verapamil infusion and 80 were randomized to receive the diltiazem infusion. There is no difference in success rate between verapamil (98.8%) and diltiazem (96.3%) infusion. The dose of medication required to convert 25, 50 and 75% of SVTs were 4.0, 5.0 and 8.0 mg for the verapamil infusion and 10.0, 12.5 and 17.5 mg for the diltiazem infusion. There was one complication in each group. Conclusion: Calcium channel blockers infusions were safe and efficacious in terminating spontaneous SVT. There was no difference between the success rates of verapamil and diltiazem infusions.

Cycling of inducibility of paroxysmal supraventricular tachycardia in women and its implications for timing of electrophysiologic procedures

Arrhythmias in women may be affected by phases of the menstrual cycle. This study was designed to determine the prevalence of perimenstrual clustering of spontaneous episodes of paroxysmal supraventricular tachycardia (SVT) in women. It also tested the hypothesis that women with this temporal pattern of events have an altered probability of induction of paroxysmal SVT during electrophysiologic testing at higher estrogen states (midcycle or with estrogen replacement therapy) than at low estrogen states (perimenstrual or without estrogen replacement). A structured history of the relation of spontaneous paroxysmal SVTs to phases of the menstrual cycle was obtained prospectively among 42 women referred during a 3-year period. Patients with cyclical patterns of spontaneous tachycardias, who had had negative electrophysiologic studies at midcycle or while receiving estrogen replacement therapy, had repeat procedures (1) when premenstrual or at the onset of menses, or (2) after stopping estrogen replacement therapy. Seventeen of 42 consecutive female patients (40%) had histories of perimenstrual clustering of arrhythmias. Six women (4 with normal menstrual cycles, 2 on estrogen replacement therapy), who qualified for paired electrophysiologic studies because of a negative initial electrophysiologic study that included provocation with isoproterenol, had inducibility into SVTs during the second study. All 6 had dual atrioventricular (AV) nodal pathway physiology, 4 had AV nodal reentrant tachycardia (AVNRT) induced, 1 had both AVNRT and reciprocating AV tachycardias, and 1 had nonsustained AVNRT and an atrial tachycardia induced. Successful ablation procedures were performed in 5 of the 6 patients. Thus, among women with a history of perimenstrual clustering of paroxysmal SVT and among those receiving estrogen replacement therapy, scheduling of elective electrophysiologic procedures at times of low estrogen levels (premenstrual or off estrogen replacement therapy) may facilitate the probability of a successful procedure.

Clinical and Electrophysiologic Characteristics and Long-Term Efficacy of Slow-Pathway Catheter Ablation in Patients With Spontaneous Supraventricular Tachycardia and Dual Atrioventricular Node Pathways Without Inducible Tachycardia

Objectives. We sought to investigate the long-term efficacy of slow-pathway catheter ablation in patients with spontaneous, documented paroxysmal supraventricular tachycardia (PSVT) and dual atrioventricular (AV) node pathways but without inducible tachycardia.Background. The lack of reproduction of clinical PSVT by programmed electrical stimulation, which is not uncommon in AV node reentrant tachycardia (AVNRT), is a dilemma in making the decision of the therapeutic end point of radiofrequency catheter ablation.Methods. Twenty-seven patients (group A) with documented but noninducible PSVT and with dual AV node pathways were prospectively studied. Programmed electrical stimulation could induce a single AV node echo beat in 12 patients, double echo beats in 4 patients and none in 11 patients at baseline or during isoproterenol infusion. Of the patients in group A, 16 underwent slow-pathway catheter ablation and 11 did not. The clinical and electrophysiologic characteristics of the 27 patients were compared with those of patients with dual AV node pathways and inducible AVNRT (group B, n = 55) and patients with dual AV node pathways alone without clinical PSVT (group C, n = 47).Results. During 23 ± 13 months of follow-up, none of the 16 patients with slow-pathway catheter ablation had recurrence of PSVT. However, 7 of the 11 patients without ablation had PSVT recurrence at 13 ± 14 months of follow-up (p < 0.03 by Kaplan-Meier analysis). Compared with groups B and C, group A consisted predominantly of men who had better retrograde AV node conduction and a narrower zone for anterograde slow-pathway conduction.Conclusions. Slow-pathway catheter ablation is highly effective in eliminating spontaneous PSVT in which the tachycardia is not inducible despite the presence of dual AV node pathways.

Renal urodilatin secretion is associated with diuresis and natriuresis after spontaneous, supraventricular tachycardia

Patients with paroxysmal supraventricular tachycardia (SVT) may have a polyuria after termination of tachycardia. There is increasing evidence that the renal peptide urodilatin (ANP (95-126))--and not plasma ANP (ANP (99-126))--is the member of the natriuretic peptide family mediating natriuresis and diuresis in man. In patients with SVT we, therefore, analyzed the relationship between diuresis, natriuresis, plasma ANP, urinary urodilatin excretion and renal excretion of cyclic GMP, the second messenger in the ANP system. During and after clinical presentation with spontaneously occurring SVT, two patients with AV-nodal and one patient with atrioventricular reentry tachycardia (heart rate 160 to 200 bpm) were studied. Urinary urodilatin excretion was correlated to diuresis (r = 0.73) and natriuresis (r = 0.93); similarly urinary cyclic GMP excretion was related to diuresis (r = 0.80) and natriuresis (r = 0.87; p < 0.001, respectively). In contrast, there was no significant correlation between plasma ANP concentrations and diuresis (r = 0.28, n.s.) or natriuresis (r = 0.11, n.s.). As an explorative analysis, stepwise multiple linear regression identified urinary urodilatin as the most important contributor to diuresis and natriuresis after SVT. These data on polyuria after spontaneous SVT further support the view that in man urodilatin is the member of the natriuretic peptide family participating in kidney physiology.

Comparison of Treatment of Supraventricular Tachycardia by Valsalva Maneuver and Carotid Sinus Massage

Study objective: To compare the efficacy of the Valsalva maneuver with that of carotid sinus massage (CSM) in terminating paroxysmal supraventricular tachycardia (SVT) in the ED. Methods: This prospective, randomized case study was performed in the ED of a tertiary care institution. Patients were at least 10 years of age with regular narrow complex tachycardia and had an ECG diagnosis of SVT. Patients with regular narrow complex tachycardia were randomly assigned to undergo either the Valsalva maneuver or CSM. If the tachycardia was not terminated by the method chosen by randomization, then the alternative method of vagal maneuver was used. If the tachycardia was not converted by both methods of vagal stimulation, patients would undergo either synchronized electrical cardioversion or a pharmacologic method of conversion at the discretion of the treating physician, depending on the patient's hemodynamic status. Results: One hundred forty-eight instances of SVT were studied. Sixty-two patients underwent Valsalva maneuver first with conversion in 12 (success rate of 19.4%). Eighty-six underwent CSM first with conversion in 9 (success rate 10.5%). Carotid sinus massage was used in the 50 cases of SVT in which conversion was not achieved with the Valsalva maneuver. Conversion occurred in 7 cases (success rate 14.0%). For the 77 cases of SVT in which initial CSM did not achieve conversion, conversion occurred in 13 with the Valsalva maneuver (success rate 16.9%). The Valsalva maneuver and CSM achieved conversion in a total of 41 instances of SVT (success rate 27.7%). Conclusion: Vagal maneuvers are efficacious in terminating about one quarter of spontaneous SVT cases. There is no detectable difference in efficacy between the Valsalva maneuver and CSM. [Lim SH, Anantharaman V, Teo WS, Goh PP, Tan ATH: Comparison of treatment of supraventricular tachycardia by Valsalva maneuver and carotid sinus massage. Ann Emerg Med January 1998;31:30-35.]

Efficacy and safely of long-term oral flecamide acetate in patients with responsive supraventricular tachycardia

In 102 patients with inducible supraventricular tachycardia (SVT), 56 women and 46 men aged 20–86 (mean, 52) years, underwent electrophysiologic study. SVTs observed at electrophysiologic study were atrial flutter or atrial fibrillation (32%), the “slow-fast” form of atrioventricular (AV) nodal reentrant tachycardia (45%), orthodromic AV reentrant tachycardia (25%), and atrial tachycardia (9%). More than 1 SVT occurred in some patients. Spontaneous symptomatic SVT frequency prior to oral flecainide varied from 3/day to 1/3 months (mean, 3/month). At electrophysiologic study and during SVT, intravenous flecainide, 2 mg/kg body weight, was given at an infusion rate of 10 mg/min up to a maximum dose of 150 mg. Patients were commenced on oral flecainide if SVT termination occurred during intravenous flecainide administration and if reinitiation was not possible after the total dose of flecainide had been given. In patients with AV nodal reentrant tachycardia and AV reentrant tachycardia further criteria for commencing oral flecainide were SVT termination by ventricularatrial conduction block and persistent ventricularatrial block after intravenous flecainide administration. Initial oral flecainide dosage was determined by assessing ability to reinitiate SVT after 50 mg, 100 mg, and the total dose of intravenous flecainide had been given. Eighty-nine patients (87%) remained free of symptomatic SVT over a mean follow-up period of 3.9 years (range, 3 months to 6.5 years). Two thirds were still taking the original dosage of flecainide and the rest were SVT-free on a higher dosage. Oral dosages ranged from 50 to 300 mg/day (median dosage, 100 mg twice daily) Nine patients experienced minor side effects, including lethargy, dizziness, headache, and blurred vision. There were no deaths and no reports of major proarrhythmic events or other major adverse effects.

Provocation of supraventricular tachycardias by an intravenous class I antiarrhythmic drug

Antiarrhythmic drugs may aggravate or induce ventricular arrhythmia. The induction of a supraventricular tachycardia or its facilitation has rarely been reported. The purpose of the study was to know whether the potential for supraventricular proarrhythmic effect of a class Ia intravenous antiarrhythmic drug can be exposed during electrophysiologic study. Ajmaline was chosen because of its short duration of action. The protocol of the study consisted of an electrophysiological study and programmed atrial stimulation using 1 and 2 extrastimuli on driven rhythm and atrial pacing up to second-degree atrioventricular block. Then 1 mg/kg of ajmaline was injected and atrial pacing was performed 3 minutes after its injection. Supraventricular proarrhythmic effect of ajmaline was defined as the spontaneous occurrence of a supraventricular tachycardia or the facilitation of its induction. Seventy patients among 1955 presented a proarrhythmic effect: 63 developed a supraventricular tachyarrhythmia (atrial flutter, fibrillation, tachycardia) and 7 an atrioventricular reentrant tachycardia, either spontaneously ( n = 23) or during atrial pacing ( n = 47). Risk factors were identified in most patients: old age, underlying heart disease, history of spontaneous supraventricular tachycardia and/or induction of a supraventricular tachycardia by 2 extrastimuli on driven rhythm in the control state (34 patients), sinus node dysfunction (22 patients). Compared with patients without proarrhythmic supraventricular effect only the history of spontaneous supraventricular tachycardia and the existence of a sinus node dysfunction were significantly more frequent ( P < 0.05) in patients with proarrhythmic effect of ajmaline. In conclusion, the supraventricular proarrhythmic effect of intravenous ajmaline exists and is related both to the electrophysiologic characteristics of the drug and to the arrhythmia substrate. The results indicate that a supraventricular tachyarrhythmia may be induced by a class I antiarrhythmic drug.

Electrophysiologic Effects and Antiarrhythmic Efficacy of Recainam in Patients with Supraventricular Tachycardia

Recainam is a new antiarrhythmic agent with class Ic properties. To evaluate its electrophysiologic effects and antiarrhythmic efficacy in patients with recurrent supraventricular tachycardia (SVT), programmed electrical stimulation was performed in 10 patients before and after intravenous recainam (loading dose 0.8 mg/kg, infusion 1 mg/kg/h), and in four patients on oral recainam 1,200 mg/day. Five patients had atrioventricular (AV) node reentrant tachycardia; five had AV-reciprocating tachycardia. There were no significant changes in electrocardiographic and intracardiac intervals after either intravenous or oral recainam. After intravenous recainam, the ventricular effective refractory period (ERP) shortened (231 +/- 14-219 +/- 9 ms, p less than 0.05). The antegrade ERP of all three bidirectional accessory pathway markedly prolonged, but the effect on retrograde accessory pathway and AV node ERPs was unremarkable. SVT induction was prevented in three of 10 patients and SVT cycle length increased modestly in seven (357 +/- 44-374 +/- 42 ms, p = 0.07). On oral recainam, an increase in the frequency of spontaneous SVT occurred in two patients. At the doses given, recainam caused less electrophysiologic change than expected, had modest antiarrhythmic efficacy, and might have significant arrhythmogenic potential.

Electrophysiological study of young patients with exercise related paroxysms of palpitation: role of atropine and isoprenaline for initiation of supraventricular tachycardia.

Electrophysiological studies were performed in eight patients (four men and four women, mean (SD) age 24 (5) years with paroxysmal attacks of palpitation during or immediately after exercise. Five patients were competitive athletes at college. In two patients spontaneous supraventricular tachycardia during exercise was recorded by ambulatory electrocardiographic monitoring and in another it was induced by treadmill exercise testing. Two had dual atrioventricular nodal pathways, three had manifest atrioventricular accessory pathways, and three had concealed atrioventricular pathways. Programmed stimulation induced sustained supraventricular tachycardia in six patients--in two after intravenous injection of atropine sulphate (1 mg) and in four during infusion of isoprenaline (0.01 microgram/kg/min). In one patient, non-sustained atrioventricular nodal reentrant tachycardia was induced during isoprenaline infusion. In the remaining patient, who had dual atrioventricular nodal pathways, tachycardia was not inducible. AH block prevented maintenance of reentry in five patients. In five patients shortening of the effective refractory period of the atrioventricular node with atropine (one patient) and isoprenaline (four patients) caused sustained supraventricular tachycardia. The present study indicates that treatment with atropine and isoprenaline may be an important factor in the initiation of supraventricular tachycardia in patients with exercise related paroxysms of palpitation.

Flecainide acetate for conversion of acute supraventricular tachycardia to sinus rhythm

The efficacy of intravenous flecainide acetate (maximum 2 mg/kg or 150 mg given at a rate of 15 mg/min) was assessed in patients with acute supraventricular, tachycardia (SVT) (within 24 hours). Fifty patients were studied, 46 with spontaneous SVT and 4 with induced SVT at. electrophysiologic assessment. Conversion to sinus rhythm was achieved within 45 minutes in 76 %: in 25 patients with atria[ fibrillation (76% conversion), 15 with atrioventricular (AV) nodal or AV reentrant tachycardia (100% conversion) and 10 with atrial flutter or atrial reentrant tachycardia (40% conversion). Adverse effects were noted in 21 patients (42%): paresthesia in 9, drowsiness in 8, nausea in 2, accelerated ventricular rate in 5, ventricular tachycardia in 1, sinus bradycardia in 1 and hypotension in 5. Adverse effects were associated with larger dosage and atrial flutter or atrial reentrant tachycardia. Thus, flecainide acetate is effective in converting to sinus rhythm acute atrial fibrillation and AV nodal and AV reentrant tachycardias, but not atrial flutter or atrial reentrant tachycardia.