Episodes Of Paroxysmal Supraventricular Tachycardia Research Articles

Efficacy and safety of out-of-hospital self-administered single-dose oral drug treatment in the management of infrequent, well-tolerated paroxysmal supraventricular tachycardia

OBJECTIVESWe tested the efficacy of two drug treatments, flecainide (F) and the combination of diltiazem and propranolol (D/P), administered as a single oral dose for termination of the arrhythmic episodes.BACKGROUNDBoth prophylactic drug therapy and catheter ablation are questionable as first-line treatments in patients with infrequent and well-tolerated episodes of paroxysmal supraventricular tachycardia (SVT).METHODSAmong 42 eligible patients (13% of all screened for SVT) with infrequent (≤5/year), well-tolerated and long-lasting episodes, 37 were enrolled and 33 had SVT inducible during electrophysiological study. In the latter, three treatments (placebo, F, and D/P) were administered in a random order 5 min after SVT induction on three different days.RESULTSConversion to sinus rhythm occurred within 2 h in 52%, 61%, and 94% of patients on placebo, F and D/P, respectively (p < 0.001). The conversion time was shorter after D/P (32 ± 22 min) than after placebo (77 ± 42 min, p < 0.001) or F (74 ± 37 min, p < 0.001). Four patients (1 placebo, 1 D/P, and 2 F) had hypotension and four (3 D/P and 1 F) a sinus rate <50 beats/min following SVT interruption. Patients were discharged on a single oral dose of the most effective drug treatment (F or D/P) at time of acute testing. Twenty-six patients were discharged on D/P and five on F. During 17 ± 12 months follow-up, the treatment was successful in 81% of D/P patients and in 80% of F patients, as all the arrhythmic episodes were interrupted out-of-hospital within 2 h. In the remaining patients, a failure occurred during one or more episodes because of drug ineffectiveness or drug unavailability. One patient had syncope after D/P ingestion. During follow-up, the percentage of patients calling for emergency room assistance was significantly reduced as compared to the year before enrollment (9% vs. 100%, p < 0.0001).CONCLUSIONSThe episodic treatment with oral D/P and F, as assessed during acute testing, appears effective in the management of selected patients with SVT. This therapeutic strategy minimizes the need for emergency room admissions during tachycardia recurrences.

Cardiac arrhythmias during sleep

Different types of cardiac arrhythmias may arise in healthy subjects during sleep. Whereas bradyarrhythmias (severe sinus bradycardia, sinus arrest, first and second degree A-V blocks) predominate in the young, elderly subjects more commonly present supraventricular and ventricular ectopic beats and tachyarrhythmias (supraventricular paroxysmal tachycardia, atrial flutter, etc.). A rare potentially life-threatening syndrome, characterised by sinus arrests accompanied by vagal overactivity, has been described in young healthy adults during REM sleep. A sudden death during sleep in apparent helthy Southeast Asian immigrants in the U.S., has been described, may be related to ventricular fibrillation. The frequency of episodes of paroxysmal supraventricular tachycardia appears to follow a circadian rhythm, presenting a minimum peak between 4 and 6 a. m. and two maximal peaks in the morning and afternoon. In contrast, the likelihood for development of an episode of paroxysmal atrial fibrillation (PAF) is the same in wakefulness, slow sleep and REM sleep. Power spectral analysis of heart rate variability has established that PAF episodes are always preceded by a shift in the sympathovagal balance towards the sympathetic limb. The influence of sleep on ventricular arrhythmias (ventricular premature beats (VPB) and ventricular tachycardia (VT)) is more controversial. Most studies show that sleep exerts an inhibitory effect on ventricular arrhythmias with a possible circadian trend (the lowest incidence occurring in the early morning hours). Our polygraphic studies failed to disclose any effect of sleep on ventricular arrhythmias. Obstructive sleep apnea syndrome (OSAS) is one of the most common causes of cardiac arrhythmias during sleep. Of these, the most frequent is brady-tachyarrhythmia. First and second degree atrioventral blocks, severe bradycardia and sinus arrests lasting over 2.5 s. (but also more than 10 s.) are also common. Even though these arrhythmias are severe, it has yet to be established whether they are a direct cause of sudden death in OSAS patients. In conclusion, even though many types of arrhythmias may arise in sleep, there is no evidence that sleep is a determinant factor. Some arrhythmias with a minimal incidence in the early hours of the morning appear to be more affected by a circadian rhythm, which are at least partly sleep-dependent. The only arrhythmias truly linked to sleep are sinus arrests in REM sleep and arrhythmias linked to obstructive sleep apneas.

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.

Circadian Variation of Paroxysmal Supraventricular Tachycardia

Various clinical manifestations of cardiovascular diseases have a pattern of circadian variation. In this study, we investigated whether the onset and duration of paroxysmal supraventricular tachycardia (PSVT) has a circadian variation. In our analysis, we included 105 patients with 498 PSVT episodes. In this study, the onset of PSVT did not have a uniform distribution throughout the 24-h period. There were nearly equal peaks in the time periods from 8:00 to 9:00 AM, 12:00 to 1:00 PM, and 5:00 to 6:00 PM, with a trough at night. The duration of PSVT also did not show a uniform distribution throughout the 24-h period; it increased significantly during the daytime, with a peak between 1:00 and 2:00 PM, another peak between 6:00 and 7:00 PM, and a significant reduction at night. The onset and duration of PSVT showed a circadian variation. However, the time-oriented antiarrhythmic therapy for preventing PSVT needs further study.

Slow Pathway Ablation in Patients With Documented but Noninducible Paroxysmal Supraventricular Tachycardia

Objectives. The purpose of this study was to assess the clinical efficacy of radiofrequency ablation of the slow pathway in patients with documented but noninducible paroxysmal supraventricular tachycardia (PSVT) who have evidence of dual atrioventricular (AV) node pathways.Background. Patients with a documented history of PSVT at times do not have inducible PSVT in the electrophysiology laboratory. Because dual AV node pathways serve as the substrate for AV node reentrant tachycardia (AVNRT), ablation of the slow pathway potentially may be useful in these patients.Methods. The subjects in this prospective study were seven consecutive patients who underwent an electrophysiologic procedure because of documented PSVT and were found to have dual AV node physiology or inducible single AV node echo beats, but no inducible PSVT despite the administration of isoproterenol and atropine. Their mean (±SD) age was 33 ± 13 years, and they had been symptomatic for 12 ± 12 years. The frequency of the episodes of PSVT ranged from ≥1/day to 1/month. The rate of the documented episodes ranged from 170 to 260 beats/min, and discrete P waves were not apparent. Slow pathway ablation was performed with 9 ± 4 applications of radiofrequency energy using a combined anatomic and electrogram mapping approach.Results. All evidence of dual AV node pathways was eliminated in six patients, and dual AV node physiology remained present in one patient. During a mean follow-up period of 15 ± 10 months (range 8 to 27), no patient had a recurrence of symptomatic tachycardia (success rate 95% confidence interval 65% to 100%).Conclusions. Slow pathway ablation may be clinically useful in patients with documented but noninducible PSVT who have evidence of dual AV node pathways.

Reciprocating supraventricular tachycardia in children: Low rate at rest as a major factor related to propensity to syncope during exercise

Reciprocating supraventricular tachycardia may have several clinical presentations, with symptoms often more severe during exercise or emotional stress. This study shows by using transesophageal atrial pacing, the factors related to syncope during exercise. Between May 1989 and June 1994, transesophageal atrial pacing was performed at rest and during exercise in 75 children aged >6 years with suspected or documented episodes of paroxysmal supraventricular tachycardia. Reciprocating supraventricular tachycardia could be induced both at rest and during exercise in 22 patients (8 girls, 14 boys; mean age 10.6 ± 2.7 years, range 7 to 15 years) with ventriculoatrial interval <70 msec in 11 patients and >70 msec in 11. At rest, all patients had palpitations caused by the induction of tachycardia. After conversion to sinus rhythm, when tachycardia was induced during exercise, symptoms did not change in 14 patients (group A), whereas symptoms worsened (presyncope) in eight (group B). The statistical analysis showed a significant difference of mean reciprocating supraventricular tachycardia rate at rest between the two groups (group A, 211 ± 23 beats/min; group B, 173 ± 33 beats/min; p = 0.0057) and reciprocating supraventricular tachycardia rate variation from rest to exercise (group A, 62 ± 18 beats/min; group B, 105 ± 24 beats/min; p = 0.0001). These data suggest that children with low tachycardia rate during normal activities may have syncope more frequently, independently of the tachycardia rate during exercise or emotional stress.

Cyclical variation in paroxysmal supraventricular tachycardia in women

Summary Background Paroxysmal supraventricular tachycardia (SVT) in premenopausal women is often judged to be related to anxiety, and may be associated with the menstrual cycle. The aim of this study was to determine whether a cyclical variation of episodes of SVT exists and to correlate such variation with cyclical variation in plasma ovarian hormones. Methods 26 women (mean age 36 [SD 8]) years; with paroxysmal SVT were screened; those with regular menses who experienced at least three episodes of paroxysmal SVT in two consecutive 48-hour ambulatory ECG recordings were included. 13 patients (aged 32 [6] years) met these criteria. Patients underwent 48-hour ambulatory ECG monitoring and determination of plasma concentrations of oestradiol-17β and progesterone on day 7, 14, 21, and 28 of their menstrual cycle. Findings An increase in the number and duration of episodes of paroxysmal SVT was observed on day 28 as compared to day 7 of the menstrual cycle. A significant positive correlation was found between plasma progesterone and number of episodes and duration of SVT (5·6 [2·2] ng/mL; r=0·83, p=0·0004; and r=0·82, p=0·0005), while a significant inverse correlation was found between plasma oestradiol-17β and number of episodes and duration of SVT (155 [22] pg/mL; r=-0·89, p<0·0001; and r=-0·81, p=0·0007). Interpretation Women with paroxysmal SVT and normal menses exhibit a cyclical variation in the occurrence of the arrhythmia with their menstrual cycle. There is a close correlation between the episodes of paroxysmal SVT and the plasma concentrations of ovarian hormones. These data suggest that changes in plasma levels of ovarian hormones (and their interaction) may be of importance in determining episodes of arrhythmia in such patients. The mechanisms of these effects are unknown.

Heart rate during spontaneous and induced paroxysmal supraventricular tachycardia.

It is generally assumed that paroxysmal supraventricular tachycardia (PSVT) induced during invasive electrophysiological study reproduces the patient's spontaneous, clinical arrhythmia. Even in the absence of antiarrhythmic drugs, however, there may be significant differences in characteristics of the induced and spontaneous arrhythmias. We compared the heart rate of PSVT in 38 patients who had undergone electrophysiological study with induction of PSVT who also had a spontaneous episode of PSVT documented by transtelephonic ECG monitoring during a period when all antiarrhythmic drugs were withheld. The heart rate during spontaneous PSVT was faster than the heart rate of PSVT induced during electrophysiological study; the mean difference was 16 beats/min (P < 0.001). We conclude that heart rate of PSVT induced during electrophysiological study generally underestimates the heart rate of spontaneous PSVT in the antiarrhythmic drug-free state. This may be due to differences in the autonomic and hemodynamic states during spontaneous and induced arrhythmias.

Post-Tachycardia T-Wave Syndrome

Figure 1. Serial electrocardiograms (lead V4) were obtained in a 67-year-old man taking digoxin for paroxysmal supraventricular tachycardia. An electrocardiogram obtained on June 28, 1983, showed no abnormalities. About six weeks later on August 15, while awaiting surgery for peripheral vascular disease, the patient had an episode of paroxysmal supraventricular tachycardia (first electrocardiogram in second row) that responded to carotid-sinus massage. An electrocardiogram obtained shortly after conversion to sinus rhythm showed atrial premature beats and minor T-wave inversions (second electrocardiogram in second row), which became deeper over the next 24 hours (third electrocardiogram in second row). The patient . . .

Efficacy and safety of intravenous amiodarone for short-term treatment of paroxysmal supraventricular tachycardia in children.

The use of intravenous amiodarone was assessed during 23 episodes of paroxysmal supraventricular tachycardia in 15 children aged 9 days to 11 years. Five of the fifteen patients had congenital structural heart disease, and three had Wolf-Parkinson-White syndrome. Tachyarrhythmias were returned to sinus rhythm during 20 of the 23 episodes (87%). No major adverse effects occurred. Recurrence of tachycardia was not observed during short-term follow-up. In conclusion, intravenous amiodarone is an effective, safe antiarrhythmic drug for short-term treatment of supraventricular tachycardia in children.

Transient sexual dysfunction observed during antiarrhythmic therapy by long-acting disopyramide in a male Wolff-Parkinson-White patient

Dear Sir, During antiarrhythmic drug therapy for various kinds of cardiac arrhythmias, not only arrhythmogenic effects, but also other minor adverse reactions, such as skin eruption, dry mouth, and urinary retention, have been recognized as causes of discontinuation and poor compliance of therapy. Recently we observed a case of another rare but significant adverse effect of an antiarrhythmic drug. The patient was a 46-year-old intellectual desk worker with intermittent Wolff-Parkinson-White syndrome. He had occasional episodes of paroxysmal supraventricular tachycardia while playing amateur baseball and drinking alcoholic beverages. We prescribed the long-acting disopyramide phosphate, 150 mg once in the morning daily, because of low efficacy of verapamil, 40 mg three times daily. On the first visit after administration of disopyramide, he complained of sexual dysfunction (impotence) without any other anticholinergic side effects. At the second visit (4 weeks after drug administration), he reported the disappearance of that adverse effect. The steady-state serum level of disopyramide in this case was 1.5 ~g/ml. Sexuality is woven into the everyday life of an individual. Sexual dysfunction is a matter of enormous importance and the cause of worry and concern. Several authors [1-4] have itemized and reviewed the characteristics of good sexual functioning and its dysfunction. Papadopoulos [3] described the significance of the actions of cardiovascular drugs as factors in sexual dysfunction of the cardiovascular patient. McHaffie et al. [2] reported a case of a 47-year-old man in whom impotence developed when the plasma concentration of the drug was 14 ~g/ml. There was full recovery of sexual function when the concentration was lowered to 3 ~g/ml. Although the anticholinergic properties of the drug may mainly impair sexual performance [2-4], the present case indicates the dependence on individual organ sensitivity to the anticholinergic action of the drug. Despite the low serum drug concentration, the adverse drug action happened as a first-dose phenomenon at the beginning of drug administration. This case also indicates that such adverse effects of the long-acting disopyramide at a low serum concentration may be transient and reversible with continued intake of the drug.

Evidence of quadruple anterograde atrioventricular nodal pathways in a patient with atrioventricular node reentry

Functional longitudinal dissociation of the atrioventricular (AV) node exhibiting two discrete discontinuities in AV nodal conduction curves suggestive of triple AV nodal pathways has been described. The authors report here unusual electrophysiologic properties of the AV node in a patient with documented episodes of paroxysmal supraventricular tachycardia. Programmed atrial extrastimuli introduced at A1–A2 coupling intervals of 390 ms with a driven cycle length of 500 ms produced a sudden marked increase of 75 ms at the A2–H2 intervals suggesting failure of the fast pathway with conduction proceeding through a slower pathway with a shorter refractory period. With further decreasing coupling intervals, a second sudden jump of 70 ms and a third one of 150 ms occurred at A1–A2 coupling intervals of 330 and 290 ms, respectively. Beyond the first sudden jump, atrial echoes occurred when sufficiently slow pathway delay permitted recovery of the fast pathway for retrograde conduction. The atrial echo zone was 170 ms. These electrophysiologic demonstrations of reentry within the AV node in a patient with clinically documented supraventricular tachycardia and the existence of four ranges of AH conduction times and refractory periods strongly suggest the presence of quadruple anterograde AV nodal pathways and a variety of potential loops available for the development of sustained AV nodal reentrant tachycardia.

Use of adenosine in the management of perioperative arrhythmias in the pediatric cardiac intensive care unit.

To assess the safety, efficacy, and diagnostic usefulness of iv adenosine in treating acute episodes of paroxysmal supraventricular tachycardia in critically ill infants and children with congenital heart disease. A consecutive sample study over a 1-yr period. A six-bed pediatric cardiac ICU at a tertiary care center. Nine consecutive critically ill infants and children with congenital heart disease, either awaiting emergent surgery or in the immediate postoperative period, who had at least one episode of tachyarrhythmia treated with iv adenosine. In children less than 50 kg, adenosine was administered in incremental doses of 100, 200, and 300 micrograms/kg every 3 mins. Patients weighing greater than 50 kg were given doses of 6, 12, and 18 mg iv. The adenosine protocol was stopped when the arrhythmia was terminated or a mechanism of the arrhythmia was shown that would not respond to adenosine administration. Adenosine was used 14 times in nine patients, all of whom were hemodynamically unstable before or after the development of the tachyarrhythmia. Adenosine was effective in rapidly terminating all nine episodes of paroxysmal supraventricular tachycardia, six of which occurred in patients known to have Wolff-Parkinson-White syndrome. All patients had marked hemodynamic improvement after conversion to normal sinus rhythm. In five episodes of tachyarrhythmia that did not respond to adenosine, the transient block at the atrioventricular (A-V) node helped determine the underlying arrhythmia without clinically important side-effects. Adenosine can be used safely and effectively in critically ill infants and children with congenital heart disease and perioperative tachyarrhythmia. More investigation into the "chemical conversion" of paroxysmal supraventricular tachycardias as well as its diagnostic value in this subset of critically ill patients is warranted.

Flecainide single oral dose for management of paroxysmal supraventricular tachycardia in children and young adults

The efficacy of a single oral dose of flecainide to terminate paroxysmal supraventricular tachycardia (PSVT) was evaluated in 25 children and young adults. The subjects were selected from a group of 35 patients with recurrent attacks of PSVT evaluated by means of electrophysiologic study and intravenous electropharmacologic testing with flecainide. In all 25 patients the induced PSVT was stopped by intravenous flecainide and was then no longer inducible or nonsustained. All patients had normal hearts. At least 48 hours after acute intravenous testing, 25 patients underwent electrophysiologic study with a transesophageal catheter and PSVT was induced in all of them: atrioventricular reentrant tachycardia in 16 and atrioventricular nodal reentrant tachycardia in nine. During stable tachycardia, a single oral dose of flecainide (2.9 ± 0.3 mg/kg; 2.5 to 3.3 mg/kg) was administered. This approach was effective for termination of PSVT in 22 patients. The mean plasma level of flecainide at cessation of tachycardia was 277 ± 92 ng/ml (150 to 500 mg/ml). All 22 patients who responded were given a single oral dose of flecainide for recurrences of PSVT during follow-up. During a period of 12 ± 7 months (2 to 27 months) a total of 134 spontaneous episodes of PSVT were reported, and 127 of these episodes were terminated with periodic management. Thus oral periodic flecainide seems useful for management of PSVT in-selected patients.

Intravenous adenosine in the emergency department management of paroxysmal supraventricular tachycardia

To evaluate the efficacy of adenosine in the treatment of emergency department patients with spontaneous paroxysmal supraventricular tachycardia (PSVT). An eight-month prospective outcome study. Patients 16 or more years old with PSVT by surface ECG criteria. Patients were excluded if there was clinical or hemodynamic evidence of hypoperfusion. Patient age, sex, PSVT rate, pretreatment blood pressure, history of cardiac disease, chronic drug therapy, and response to IV adenosine. Twenty-three patients with 27 episodes of suspected PSVT met inclusion criteria. After IV adenosine, two patients were found to have atrial flutter, and one was found to have ventricular tachycardia. Twenty-four episodes of PSVT were diagnosed in the remaining 21 patients. There were eight male and 13 female patients with a mean age of 51 +/- 19 years (range, 16 to 80 years). Sixteen patients related a history of cardiovascular disease. The mean QRS rate during PSVT was 181 +/- 23. Twenty-three of 24 episodes (96%) were converted to sinus rhythm within 20 to 45 seconds of adenosine therapy. However, 13 of 23 of initial conversions (57%) were followed by recurrence of PSVT within five minutes. All 13 recurrences required therapy with other antiarrhythmic drugs for conversion to and maintenance of sinus rhythm. Complications of adenosine were noted in only four patients and were transient and clinically unimportant. IV adenosine effectively terminates PSVT in ED patients with spontaneous PSVT; recurrence of PSVT after adenosine is common in the ED population and should be treated with other antiarrhythmic agents, not repeated doses of adenosine; adenosine is useful in the differential diagnosis of tachyarrhythmias; and doubling the initial dose of adenosine to 12 mg would increase the likelihood of conversion with the first dose.

Adenosine

Adenosine (adenine riboside), administered either as the free base or as the 5'-triphosphate (ATP) by rapid intravenous bolus, depresses atrioventricular (AV) nodal conduction, resulting in transient AV block. Adenosine is the active agent and ATP is rapidly converted to adenosine after exogenous administration. By blocking the anterograde AV nodal limb of a re-entrant circuit, adenosine 6 to 12 mg (or ATP 10 to 20 mg) converts almost all episodes of paroxysmal supraventricular tachycardia (PSVT) involving the AV node within 30 seconds of administration. This is at least equivalent in efficacy to verapamil in adults, and superior to lanatoside C in children, with a considerably more rapid onset of action. Furthermore, if a dose of adenosine is ineffective, the exceptionally short plasma half-life of the adenyl nucleosides (less than 10 sec) allows rapid upward dosage titration until PSVT is terminated. Because the induced conduction block primarily affects the AV node, adenosine is a useful diagnostic tool in patients with broad or narrow QRS complex tachycardia; it terminates arrhythmias dependent on the AV node, unmasks other supraventricular mechanisms during transient AV block, but almost always has no effect on ventricular tachycardia. Noncardiac adverse effects, i.e. flushing, dyspnoea and chest pain, may occur during acute arrhythmia termination or diagnosis with adenosine, and arrhythmias may develop; however, these effects are usually transient (lasting less than 1 minute). Adenosine has also been used to induce coronary vasodilation in patients undergoing thallium-201 single photon emission computed tomography (201Tl SPECT), 2-dimensional echocardiography or positron emission tomography to evaluate suspected coronary artery disease. Intravenous infusion of adenosine 140 micrograms/kg/min for 6 minutes was generally associated with only mild adverse effects. These usually resolved within 1 to 2 minutes of discontinuing adenosine, although occasionally patients required aminophylline and/or nitroglycerin (glyceryl trinitrate). Diagnoses based on the results of scintigraphy were of a sensitivity, specificity and predictive accuracy comparable to those achieved with exercise- or dipyridamole-201Tl SPECT. Adenosine is therefore particularly suitable for the diagnosis of tachycardias and the acute management of PSVT involving the AV node in all age groups, without the risks of cardiac arrest and hypotension associated with verapamil. Furthermore, intravenous adenosine infusion may be used to induce coronary vasodilation in patients unable to perform exercise stress tests for 201Tl scintigraphy, and is well tolerated.

Flecainide acetate prevents recurrence of symptomatic paroxysmal supraventricular tachycardia. The Flecainide Supraventricular Tachycardia Study Group.

Oral flecainide acetate was administered to 34 patients with documented symptomatic paroxysmal supraventricular tachycardia (PSVT) with a double-blind, placebo-controlled, 8-week crossover trial design. PSVT was defined as a regular tachycardia of at least 120 beats/min without evidence of atrioventricular dissociation. The study required considerable patient cooperation. Patients first entered a 4-week qualifying phase followed by a 3-week, open label, flecainide dose-ranging phase. They were then randomized in a blind fashion to receive either placebo or tolerated flecainide dose for an 8-week treatment period and then crossed over after four symptomatic documented episodes of PSVT or at the end of the treatment period. By all efficacy parameters analyzed, flecainide was superior to placebo. Flecainide was associated with an actuarial 79% freedom from symptomatic PSVT events compared with only 15% on placebo at 60 days (p less than 0.001). Of the 34 patients, 29 had recurrence of symptomatic PSVT at least once during the placebo phase; only eight patients had a recurrence during the flecainide phase (p less than 0.001). The median time to the first symptomatic PSVT event was 11 days in the placebo group and greater than 55 days in the flecainide group (p less than 0.001). Likewise, the interval between attacks was a median of 12 days on placebo compared with more than 55 days on flecainide (p less than 0.001). Finally, the flecainide slowed symptomatic PSVT heart rates to 143 +/- 12 beats/min from 178 +/- 12 on placebo (p less than 0.02) in the seven patients who had events in the placebo and flecainide treatment phases.(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise testing for assessment of the significance of ST segment depression observed during episodes of paroxysmal supraventricular tachycardia

Sixteen patients who had manifested ST segment depression during episodes of paroxysmal supraventricular tachycardia (PSVT) were studied with exercise testing in order to detect coronary artery disease and myocardial ischaemia. No ST segment depression was observed during exercise testing in 15 out of the 16 patients tested. Paroxysms of supraventricular tachycardia associated with ST segment depression occurred during exercise testing in three cases. The ST segment depression was immediately apparent, remained constant throughout the supraventricular tachycardia and was almost instantly abolished following conversion to sinus rhythm. Patients with heart rates greater than 250 beats min-1 during PSVT had marked ST segment depression associated with the tachycardia. These results suggest that coronary artery disease and myocardial ischaemia are not involved in the genesis of ST segment depression during PSVT. Tachycardia per se may be the cause of ST segment depression by altering the slope of phase 2 of the ventricular action potential. Retrograde atrial activation may also induce ST segment shifts in some of the cases.

Adenosine for Paroxysmal Supraventricular Tachycardia: Dose Ranging and Comparison with Verapamil

To assess the safety and efficacy of intravenous adenosine in terminating acute episodes of paroxysmal supraventricular tachycardia. Two prospective, double-blind, randomized, placebo-controlled trials to evaluate dose response in patients receiving adenosine and to compare the effects of adenosine with those of verapamil. A total of 359 patients with a tachycardia electrocardiographically consistent with paroxysmal supraventricular tachycardia were entered into the two protocols. Patients subsequently found to have arrhythmias other than paroxysmal supraventricular tachycardia were excluded from the efficacy analysis. 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. 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. Adenosine in graded 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.

Treatment of paroxysmal supraventricular tachycardia in the emergency department by clinical decision analysis

Vagal maneuvers terminate new onset, catheter-induced paroxysmal supraventricular tachycardia (PSVT) in up to 92% of patients. The risk and benefit of vagal maneuvers for treating PSVT in the emergency department (ED) is inadequately defined. The purpose of this study was to determine the efficacy of nonpharmacological vagal interventions in converting spontaneous episodes of PSVT in adult patients and to derive a treatment plan for such patients based on clinical decision analysis. Seventeen adult patients who presented to the ED because of PSVT were treated with carotid sinus massage, Valsalva maneuver, and head-down tilt (alone and in combination). Only three patients converted out of PSVT with vagal intervention. The remainder received verapamil, which converted 12 of the 14 patients (86%) who received the drug (one required digoxin, one required synchronized cardioversion). Vagal maneuvers are safe in young, otherwise healthy patients but problems have been documented in the literature in older patients, who have a higher likelihood of coronary and/or cerebrovascular disease. Clinical decision analysis indicates that young patients should be treated initially with vagal maneuvers but that older patients (above approximately 65 years of age) should be treated initially with verapamil.