title: Electrophysiological mechanisms and determinants of vagal maneuvers for termination of paroxysmal supraventricular tachycardia. Acute conversion of paroxysmal supraventricular tachycardia with intravenous diltiazem. IV Diltiazem Study Group. Adenosine cardioprotection study in clinical setting of paroxysmal supraventricular tachycardia. Comparison of Treatment of Supraventricular Tachycardia by Valsalva Maneuver and Carotid Sinus Massage. Randomized controlled trial of midazolam premedication to reduce the subjective adverse effects of adenosine. Efficacy of intravenous magnesium sulphate in supraventricular tachyarrhythmias. Adenosine for paroxysmal supraventricular tachycardia: dose ranging and comparison with verapamil. Assessment in placebo-controlled, multicenter trials. The Adenosine for PSVT Study Group. Adenosine versus verapamil in the treatment of supraventricular tachycardia: a randomized double-crossover trial. Adenosine: a clinical experience and comparison with verapamil for the termination of supraventricular tachycardias.
abstract: BACKGROUND The vagal maneuvers used for termination of paroxysmal supraventricular reentrant tachycardia ( PSVT ) appear to involve more complex mechanisms than we have known , and further study should be done to explore the possible mechanisms . METHODS AND RESULTS In this study , 133 patients with PSVT and 30 age- and sex-matched control subjects were included . We assessed the effects of different vagal maneuvers on termination of PSVT and compared baroreflex sensitivity and beta-adrenergic sensitivity between the patients with PSVT and control subjects . Out of 85 patients with atrioventricular reciprocating tachycardia ( AVRT ) , vagal maneuvers terminated in 45 ( 53 % ) . Of these , 28 ( 33 % ) terminated in the ante grade limb and 17 ( 20 % ) terminated in the retro grade limb . Out of 48 patients with atrioventricular nodal reentrant tachycardia ( AVNRT ) , vagal maneuvers terminated the tachycardia in the ante grade slow pathway ( 14 % ) or in the retro grade fast pathway ( 19 % ) . Baroreflex sensitivity was poorer but isoproterenol sensitivity test better in patients with AVNRT . Poorer ante grade atrioventricular node conduction properties and better vagal response determined successful ante grade termination of AVRT by vagal maneuvers . Poorer retro grade accessory pathway conduction property but better vagal response determined successful retro grade termination of AVRT . Better sympathetic and vagal response associated with poorer retro grade atrioventricular node conduction determined retro grade termination of AVNRT by the Valsalva maneuver . CONCLUSIONS Both the vagal response and conduction properties of the reentrant circuit determine the tachycardia termination by vagal maneuvers . Improved underst and ing of the interaction of autonomic and electrophysiological mechanisms in maintaining or terminating PSVT may provide important insight into the pathophysiology of these two tachycardias Diltiazem has electrophysiologic effects similar to those of verapamil . Its efficacy and safety in 4 doses for treatment of induced supraventricular tachycardia ( SVT ) were examined and compared with those of placebo in 87 patients ( 25 with atrioventricular [ AV ] nodal reentry tachycardia , 60 with AV reentry associated with an accessory AV connection , and 2 with atrial tachycardia ) .  Conversion to sinus rhythm occurred in 4 of 14 patients ( 29 % ) with 0.05 mg/kg of diltiazem , 16 of 19 ( 84 % ) with 0.15 mg/kg , 13 of 13 ( 100 % ) with 0.25 mg/kg , and 14 of 17 ( 82 % ) with 0.45 mg/kg compared with 6 of 24 ( 25 % ) treated with placebo .  Conversion rates in groups receiving doses of 0.15 to 0.45 mg/kg of diltiazem were superior to that in the placebo group ( p less than 0.001 ) . Time to conversion was 3.0 + /- 2.6 minutes in responding diltiazem patients compared with 5.9 + /- 6.1 minutes in responding control patients . Diltiazem administration result ed in significant lengthening of SVT cycle length , AH interval , and AV nodal effective refractory period and block cycle length . The most frequent adverse response to diltiazem was hypotension ( 7 of 63 patients ) ; however , only 4 patients had symptoms related to hypotension . Thus , intravenous diltiazem in doses of 0.15 , 0.25 and 0.45 mg/kg is an effective and safe treatment for the acute management of SVT PSVT attack of > 20min and frequency > 160 is well-recognized model of myocardial dysfunction . We measured 6-keto-PGF1alpha and TXB(2 ) before and after adenosine administration to assess its cardioprotective potential . A total of 64 patients were r and omly assigned as having acute episode of PSVT to adenosine or verapamil group . A bolus of 6 mg of adenosine up to the maximum dose of 12 or 5 mg of verapamil up to the maximum dose of 10 mg were given , until the sinus rhythm was restored . The levels of PGI(2 ) , TXA(2 ) and TAS were measured in three different time intervals . In adenosine group all parameters were normalized after 20min of conversion to sinus rhythm . The ratio of PGI(2)/TXA(2 ) increased after 5min of conversion to SR ( P<0.01 ) . Also , the ratio of TXA(2)/TAS was decreased for ADO ( P<0.01 ) . This is the first study to demonstrate that adenosine exerts cardioprotective effect 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 prospect i ve , r and omized 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 r and omly assigned to undergo either the Valsalva maneuver or CSM . If the tachycardia was not terminated by the method chosen by r and omization , 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 . ] OBJECTIVE To determine the safety and efficacy of midazolam premedication to minimize the subjective adverse effects of adenosine . METHODS Double-blind prospect i ve r and omized controlled trial of patients presenting to an urban emergency department . Included were a convenience sample of patients who would have received adenosine by the existing department protocol . Exclusion criteria were pregnancy , benzodiazepine allergy , regular benzodiazepine medication , alcoholism , altered mental state ( precluding informed consent ) , and age less than 18 or greater than 65 years . Subjects received either 1.5 mg of intravenous midazolam or normal saline placebo 5 min prior to the administration of adenosine . Side-effect recall was judged by a question naire at 1 h and 24 h postadenosine administration . RESULTS A total of 34 patients were recruited into the trial , 16 in the placebo group and 18 in the midazolam group . The groups were well matched for demographics , treatment and outcome . There was a significant reduction in the midazolam group for complaint scores of palpitations ( P = 0.04 ) and chest pain ( P = 0.02 ) and a trend to reduction in complaint scores for most other parameters . There were no adverse outcomes in any of the patients studied . CONCLUSIONS Co-administration of midazolam can safely reduce the recall of the unpleasant adverse effects of adenosine . Its use may be most appropriate in patients who are particularly anxious or have had previous adverse experiences with adenosine This study was conducted to evaluate the clinical efficacy of intravenous ( i.v . ) magnesium sulphate 2 gm bolus in sustained supraventricular tachycardia ( SVT ) and atrial flutter-fibrillation with fast ventricular rate of more than 160/min ( AF-FVR ) and to compare it with i.v . verapamil 5 mg . In this r and omised controlled trial , 68 cases of SVT and 86 cases of AF-FVR were studied . Patients with evidence of renal dysfunction and systolic blood pressure less then 90 mm Hg were excluded . Response was considered when the heart rate fell to less than 100/min . In SVT , 33.3 % ( 11 out of 33 ) responded to magnesium sulphate which was significantly less than verapamil ( 23 out of 35 , 65.7 % ) p = 0.007 . Similarly , in AF-FVR , response was more with verapamil ( 25 out of 45 , 55.6 % ) than magnesium sulphate ( 8 out of 41 , 19.5 % ) p < 0.0001 . Response to magnesium sulphate was better in patients with IHD . There were no significant side effects , except flushing and sense of warmth with i.v . magnesium sulphate .  Serum magnesium rose significantly after i.v . magnesium bolus . Though magnesium sulphate is a weaker antiarrhythmic drug than verapamil , further studies are needed to identify subgroups of supraventricular tachyarrhythmias which would respond to magnesium sulphate OBJECTIVE To assess the safety and efficacy of intravenous adenosine in terminating acute episodes of paroxysmal supraventricular tachycardia .  DESIGN Two prospect i ve , double-blind , r and omized , placebo-controlled trials to evaluate dose response in patients receiving adenosine  and to compare the effects of adenosine with those of verapamil . PATIENTS A total of 359 patients with a tachycardia electrocardiographically consistent with paroxysmal supraventricular tachycardia were entered into the two protocol s. Patients subsequently found to have arrhythmias other than paroxysmal supraventricular tachycardia were excluded from the efficacy analysis . INTERVENTIONS The first protocol compared sequential intravenous bolus doses of 3 , 6 , 9 , and 12 mg of adenosine to equal volumes of saline . In the second protocol , patients received either 6 mg and , if necessary , 12 mg of adenosine or 5 mg and , if necessary , 7.5 mg of verapamil . MEASUREMENTS AND MAIN RESULTS When data are expressed in terms of cumulative response in eligible patients , intravenous adenosine terminated acute episodes of paroxysmal supraventricular tachycardia in 35.2 % , 62.3 % , 80.2 % , and 91.4 % of patients who received maximum doses of 3 , 6 , 9 , and 12 mg , respectively , in a four-dose sequence , whereas 8.9 % , 10.7 % , 14.3 % , and 16.1 % of patients responded to four sequential placebo doses ( P less than 0.0001 ) . In the second trial , cumulative response rates after 6 mg followed , if necessary , by 12 mg of adenosine were 57.4 % and 93.4 % , and after 5 mg followed , if necessary , by 7.5 mg of verapamil were 81.3 % and 91.4 % . The average time after injection to termination of tachycardia by adenosine was 30 seconds . Adenosine caused adverse effects in 36 % of patients , but they lasted less than 1 minute and were usually mild . CONCLUSIONS Adenosine in grade d doses up to 12 mg rapidly and effectively terminates acute episodes of paroxysmal supraventricular tachycardia in which the atrioventricular node is an integral part of the re-entrant circuit . The overall efficacy of adenosine is similar to that of verapamil , but its onset of action is more rapid . Adverse reactions to adenosine are common but are minor and brief The safety and efficacy of verapamil and adenosine in the acute termination of supraventricular tachycardia were compared in a r and omized double-crossover trial . Of 32 eligible patients with either spontaneous or induced narrow complex tachycardia , seven ( 22 % ) patients experienced conversion to sinus rhythm with carotid sinus massage . The other 25 patients were r and omly assigned to receive either adenosine ( n = 14 ) or verapamil ( n = 11 ) . Relative drug efficacies were 100 % for adenosine versus 73 % for verapamil , p = NS . Adenosine given at less than or equal to 120 micrograms/kg caused conversion in 12 ( 86 % ) of 14 patients . The other two patients required 20 mg adenosine for conversion . After conversion the systolic blood pressure increased significantly in the adenosine group but not in the verapamil group . Reinitiation of tachycardia occurred in two ( 14 % ) of 14 patients r and omized to the adenosine group . Serious adverse hemodynamic effects were observed in one ( 9 % ) of 11 patients r and omized to verapamil . The incidence of conversion arrhythmias was similar in both treatment groups ( adenosine 57 % , verapamil 50 % , p = NS ) The efficacy and side-effects of adenosine for treatment of supraventricular arrhythmias were compared to verapamil therapy in patients presenting to the emergency room . Clinical variables and the time interval from the initiation of treatment to the termination of the supraventricular tachycardia , as well as the time from the initial effective dose of medication to the termination of supraventricular tachycardia were compared for adenosine and verapamil . Adenosine was given to a total of 44 patients , 16 patients in the electrophysiology laboratory , and 28 patients in the emergency room for evaluation and termination of their tachycardia . In the electrophysiology laboratory , 7 patients had AV node reentry , 5 had Wolff-Parkinson-White syndrome , 2 of whom had atrial flutter and fibrillation but no bypass tract reentry , 1 had concealed bypass tract reentry , 1 had Lown-Ganong-Levine syndrome , 1 had intraatrial reentry , and 1 had an automatic atrial tachycardia . Twenty-five patients received  adenosine in the emergency room and 3 patients in the hospital for 31 episodes of supraventricular arrhythmias . In the emergency room , 11 patients had supraventricular tachycardia due to AV node reentry , 3 had Wolff-Parkinson-White syndrome , 6 had atrial flutter or intra-atrial re-entry , 2 had ventricular tachycardia , and 3 had sinus tachycardia . In the hospital , 2 patients had atrial flutter and one had sinus tachycardia . The group of 14 patients with supraventricular tachycardia due to Wolff-Parkinson-White syndrome or AV node reentry presenting in the emergency room were compared in a retrospective manner to the patients treated with st and ard verapamil therapy with respect to time from initiation of therapy to termination of supraventricular tachycardia and time from effective dose of medication to the termination of supraventricular tachycardia , as well as side-effects . There was no significant difference between the two groups with respect to clinical variables .  Adenosine converted 18 of 18 episodes of supraventricular tachycardia in 14 patients 24.6 + /- 9.6 seconds from the administration of the effective dose ( 0.104 + /- 0.024 mg/kg ) and a mean of 4.4 + /- 2.0 minutes from the initiation of therapy . Verapamil converted 29 of 32 episodes of supraventricular tachycardia in 20 patients , 10.9 + /- 7 minutes from the administration of the effective dose , and a mean of 16.8 + /- 20 minutes from the initiation of therapy using a mean of 8.4 + /- 3.4 mg of IV verapamil . ( ABSTRACT TRUNCATED AT 400 WORDS
target: In the pooled analysis there was no significant difference in reversion rate or relapse rate between the two drugs .
  Adenosine and verapamil are both effective treatments for supraventricular tachycardia in the majority of patients .
background: BACKGROUND Patients with paroxysmal supraventricular tachycardia frequently present to the Emergency Department .
  Where vagal manoeuvres fail , the two most commonly used drugs are adenosine and calcium channel antagonists .
  Both are known to be effective but both have a significant side-effect profile .
  OBJECTIVES To examine the relative effects of adenosine and calcium channel antagonists and , if possible , to determine which is most appropriate for the management of supraventricular tachycardia .