33. Am J Cardiol. If these methods fail to terminate the SVT, or if the SVT soon returns, pharmacologic therapy is used. RANDALL A. COLUCCI, DO, MPH, Ohio University College of Osteopathic Medicine, Athens, Ohio, MITCHELL J. Byrd RC, The term supraventricular tachycardia (SVT), whilst often used synonymously with AV nodal re-entry tachycardia (AVNRT), can be used to refer to any tachydysrhythmia arising from above the level of the Bundle of His. Your symptoms get worse, or you have new symptoms. Smith WM, Symptoms since early childhood suggest supraventricular tachycardia. With SVT… Ohara T, This is what AHA recommends and also SVT converts quite readily with 50-100 J. Mickelsen S, Nom d'utilisateur. Glatter KA, JAMA. et al. The 12-lead electrocardiogram in supraventricular tachycardia Cardiol Clin. Brady WJ, et al. Cumberbatch G. Mon Profil.   Miles WM. Duray G, Belardinelli L, Don't miss a single issue. L'application est très pratique pour réviser son bac, son brevet, un contrôle, à la maison, dans le bus ou juste avant d'entrer dans la salle. Vereckei A, Conseils pour l'écrit (Sara Kozierow). 38. Wolfram S, et al. Belardinelli L, 36. Goldberg AS, 2006;29(7):769–778. A new approach to the differential diagnosis of a regular tachycardia with a wide QRS complex. Am Heart J. Sinus tachycardia starts and stops gradually. There are risks, and the procedure is expensive, but it helps in 80-90% of all cases. Brugada criteria are sensitive and specific in helping distinguish between SVT with aberrancy and ventricular tachycardia. A narrow QRS complex (less than 120 msec) usually indicates SVT, and the Valsalva maneuver is the most widely used and feasible treatment option in an alert patient. Ganz LI, Maisel WH, Tu souhaites t'améliorer en SVT 4e ? 2006;24(3):427–437ix. DiMarco JP, Mayo Clin Proc. Emerg Med J. Non-invasive diagnosis of concealed Wolff-Parkinson-White syndrome by detection of concealed anterograde pre-excitation. Epstein AE, Atrioventricular nodal reentry. Morphologic criteria for VT* present in precordial leads V1 to V2 and V6, Supraventricular tachycardia with aberrant conduction is diagnosis made by exclusion. 23. Reduce maximum velocity (rate of rise of action potential upstroke [phase 0]), Kinetics of onset and offset in blocking the sodium channel are of intermediate rapidity (less than five seconds), Examples include quinidine, procainamide, disopyramide (Norpace), Kinetics of onset and offset in blocking the sodium channel are rapid (less than 500 msec), Examples include mexiletine, phenytoin (Dilantin), lidocaine (Xylocaine), Kinetics of onset and offset in blocking the sodium channel are slow (10 to 20 seconds), Examples include flecainide (Tambocor), propafenone (Rythmol), Examples include propranolol (Inderal), timolol, metoprolol, Predominantly block potassium channels (e.g., inward rectifier potassium channels), Examples include sotalol (Betapace), amiodarone (Cordarone), Predominantly block the slow calcium channel (e.g., L-type calcium channel), Examples include verapamil, diltiazem, nifedipine (Procardia), felodipine (blocks T-type calcium channel), Examples include adenosine (Adenocard), digoxin, magnesium sulfate. et al. et al. In those who require long-term pharmacotherapy, atrioventricular nodal blocking agents or class Ic or III antiarrhythmics can be used; however, these agents should generally be managed by a cardiologist. Instead, it comes from another part of the left or right atrium, or from the AV node. Sinus tachycardia must be considered in the differential diagnosis. Nawman R, 6ème. This example represents atrioventricular nodal reentrant tachycardia, which is also depicted in Figure 1A. ACC/AHA/ESC guidelines for the management of patients with supraventricular arrhythmias— executive summary. 29. Marill KA, Fenelon G, Altemose GT, Akhtar M, Kastor JA. Date de … Tachycardiomyopathy: mechanisms and clinical implications. Kastor JA. et al. This content is owned by the AAFP. West G, Cost-effectiveness of radiofrequency ablation for supraventricular tachycardia [pubished correction appears in, A more recent article on supraventricular tachycardia is available, Radiologic Evaluation of Chronic Neck Pain. Comparison of the efficacy and safety of esmolol, a short-acting beta blocker, with placebo in the treatment of supraventricular tachyarrhythmias. The cardiac effects of adenosine. Andries EW.   Multifocal atrial tachycardia. 2007;298(23):2768–2778. Any combination of these symptoms suggests supraventricular tachycardia, especially in patients with Wolff-Parkinson-White syndrome, Supraventricular tachycardia starts and stops quickly (within seconds). At what age did the symptoms begin (time of onset)? Delacrétaz E. Wilkinson WE. Mont L, 41. Dailey SM, Prénom. Gallagher JJ. The adenosine for PSVT study group [published correction appears in. Mitrani RD, Pour réviser L’évolution de la biodiversité, découvre les fiches de révisions complètes d'Afterclasse. Supraventricular tachycardia. Patients may also be asymptomatic or minimally symptomatic, potentially delaying diagnosis. It is a short-acting agent that alters potassium conductance into cells and results in hyperpolarization of nodal cells. Reimold SC, It may last from a few seconds or hours to several days. 1986;111(1):42–48. Reimold SC, Menozzi C, 16. terminale S. Plan du site. Blanski L, et al. The primary options include catheter ablation (radiofrequency versus cryotherapy) or pharmacologic treatment (Table 6).22 Figure 7 is an algorithm for the long-term management of SVT.19. Brugada J, Krahn AD, Afterclasse Premium. Preexcitation syndromes: diagnostic considerations in the ED. Fuster V, Potential for misdiagnosis as panic disorder. Table 1 describes ECG findings for common types of SVT.3–6. et al. The next option for patients who still remain in SVT is intravenous adenosine. / *—For complete morphologic criteria, see Brugada P, Brugada J, Mont L, Smeets J, Andries EW. Supraventricular tachycardia (SVT) is a condition that causes your heart to beat much faster than it should. Pritchett EL, Libby P, ed Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine 8th ed Philadelphia, Pa: W.B. (B) In atrioventricular reciprocating tachycardia, there is typically a short RP interval, with the timing and morphology of the P wave dependent on the site and conduction velocity of the accessory pathway. Vidéos sur la méthode pour l'épreuve écrite It provides an environment to simulate different cardiac arrhythmias and allows the user to perform various diagnostic maneuvers by pacing … L'application est très pratique pour réviser juste avant un contrôle, à la maison, dans le bus ou juste avant d'entrer dans la salle. 2006;354(10):1039–1051. Am J Cardiol. Propafenone for the treatment of supraventricular tachycardia and atrial fibrillation: a meta-analysis. Yee R. Akhtar M, Algorithm of the short-term management of supraventricular tachycardia (SVT). Anderson S, Mes classes. 1993;88(1):282–295. Hackett FK, (A) In typical atrioventricular nodal reentrant tachycardia (antegrade conduction down the slow atrioventricular nodal pathway and retrograde conduction up the fast pathway), the retrograde P wave may not be seen or may be visible early after the QRS complex. Mes enfants. Supraventricular tachycardia. Adenosine for wide-complex tachycardia: efficacy and safety. Influence of age and gender on the mechanism of supraventricular tachycardia. For some patients Atenolol works very well, and there do not appear to be any long-term side effects of beta-blockers that differ from the short-term ones. Skanes AC, Sign up for the free AFP email table of contents. Les cours de SVT‎ > ‎ terminale S. Documents de rentrée : Term S présentation programme exigences évaluation.doc. Nom. Crit Care Med. Catheter ablation therapy for supraventricular arrhythmias. Clinical practice. Boyle M. et al. RS complex absent from all precordial leads, 2. et al. Hervé Mulard – Cours de SVT de Terminale S1 – Lycée Agora de Puteaux – 2009-2010 La mesure du temps dans l’histoire de la Terre et de la vie Introduction : Depuis l’invention de l’écriture il y a 5300 ans, un certain nombre d’événements ont pu être enregistrés et gravés dans l’histoire de l’Homme. Krahn AD, Akhtar M, Paroxysmal supraventricular tachycardia in the general population. Patients with this arrhythmia typically present at a younger age than those with AVNRT. Prog Cardiovasc Dis. RANDALL A. COLUCCI, DO, MPH, is an assistant professor of family medicine at Ohio University College of Osteopathic Medicine, Athens.... MITCHELL J. Tachycardiomyopathy: mechanisms and clinical implications. Heart Rhythm. Patient history is important in uncovering the diagnosis, whereas the physical examination may or may not be helpful. Sanders GD, Cannom DS, You have dizziness, lightheadedness, or feel faint. et al. Kusumoto FM. Paroxysmal supraventricular tachycardia in the general population. JAY SHUBROOK, DO, is an associate professor of family medicine and director of clinical research at Ohio University College of Osteopathic Medicine. 32. Adapted from Delacrétaz E. Clinical practice. Andries EW. The Esmolol vs Placebo Multicenter Study Group. Linden J, Podczeck A, et al. Long RP tachycardias result when atrial activity precedes the QRS complex. Sujets d'écrit (académie de Besançon). It is called "supraventricular" because the signal begins someplace above your ventricles. The most common type of SVT is AVNRT. Radiofrequency ablation for atrioventricular node reentrant tachycardia: comparison between fast (anterior) and slow (posterior) pathway ablation. 82/No. N Engl J Med. Dailey SM, Haqqani HM, 17. Blanck Z, Mathématiques, Physique-Chimie, SVT, Philo You have questions or concerns about your condition or care. Valvular heart disease causing heart failure or tachycardia, Possible atrioventricular nodal reentrant tachycardia or ventricular tachycardia, Hyperthyroidism or thyroiditis resulting in tachycardia, Hemodynamic instability or febrile illness, Type of SVT versus ventricular tachycardia, Ischemia leading to ventricular tachycardia, All possibly induce or incite tachyarrhythmia, Congestive heart failure or cardiomyopathy, Capture aberrant rhythm, frequency, duration, A 12-lead ECG should be performed in patients who are hemodynamically stable, with special attention to rhythm and rate, atrioventricular conduction (PR interval), RP interval, hypertrophy, pathologic Q waves, prolongation of the QT interval, and any evidence of preexcitation. 2009;27(7):878–888. Role of radiofrequency ablation in the management of supraventricular arrhythmias: experience in 760 consecutive patients. Linden J, Roberts-Thomson KC, Adenosine should not be used in persons with Wolff-Parkinson-White syndrome and atrial fibrillation because this rhythm can degenerate into ventricular fibrillation.24 There is poor evidence that medical therapy reduces sudden death in patients with Wolff-Parkinson-White syndrome; therefore, expedient referral for ablation is recommended in those patients who are symptomatic.2,25 Because AT is an atrioventricular nodal-independent SVT, atrioventricular nodal blocking agents, such as verapamil or adenosine, are mostly ineffective in its termination.26, Verapamil is a calcium channel blocker that may be used in patients with SVT that recurs after adenosine therapy. Long-term therapy of paroxysmal supraventricular tachycardia: a randomized, double-blind comparison of digoxin, propranolol and verapamil. The differential diagnosis includes atrial tachycardia, atrioventricular nodal reentrant tachycardia, and orthodromic atrioventricular reciprocating tachycardia. Afterclasse te fait mémoriser ton cours à coup sûr ! Deshpande S, Background: In patients with cardiovascularly stable supraventricular tachycardia (SVT), the valsalva maneuver is recommended as an initial maneuver to help with cardioversion. J Am Coll Cardiol. SVTs (excluding atrial fibrillation or flutter and multifocal AT) have an estimated incidence of 35 per 100,000 person-years, with a prevalence of 2.29 per 1,000 persons.7 Although AVNRT is the most common SVT in adults (approximately 50 to 60 percent),4 AVRT is most common in children (accounts for approximately 30 percent of all SVTs).4,5. He will also listen to your heart and lungs. Supraventricular tachycardia, For complete morphologic criteria, see Brugada P, Brugada J, Mont L, Smeets J, Andries EW. Smith G, Cochrane Database Syst Rev. Mark DG, Hlatky MA, Sanders GD, Brugada J, 6ème 5ème 4ème 3ème 2nde Première Terminale. This article focuses on the most common types of paroxysmal SVT: atrioventricular nodal reentrant tachycardia (AVNRT), atrioventricular reciprocating tachycardia (AVRT), and atrial tachycardia (AT). Winniford MD, 2006;114(7):e257–e354.... 2. Budde T, Kalman JM. svtsim is a a web-based cardiac electrophysiology study (EPS)/arrhythmia simulator, which is primarily designed for training and education. Efficacy and safety of out-of-hospital self-administered single-dose oral drug treatment in the management of infrequent, well-tolerated paroxysmal supraventricular tachycardia. 14. Symptoms of SVT depend on a number of factors, including patient age, presence of comorbid heart and lung disease, and duration of SVT episodes. The adenosine for PSVT study group [published correction appears in Ann Intern Med. Friedman PL. Tischenko A, et al. Mortality in patients treated with flecainide and encainide for supraventricular arrhythmias. Focal atrial tachycardia II: management. Catheter ablation therapy for supraventricular arrhythmias. 2001;135(10):933]. 2001;85(2):193–223ix. PATIENT DEMOGRAPHY. Desouza IS, However, observational studies have reported that patients undergoing radiofrequency ablation for SVT have better overall quality-of-life outcomes and lower costs attributed to therapy compared with medical treatment.41,42. Kay GN, DeStefano F, Drugs.com provides accurate and independent information on more than 24,000 prescription drugs, over-the-counter medicines and natural products. Strasburger JF, 2008;83(12):1400–1411. Non-invasive diagnosis of concealed Wolff-Parkinson-White syndrome by detection of concealed anterograde pre-excitation. The success rate of the valsalva maneuver alone is documented at 5 – 20%. Algorithm of the long-term management of supraventricular tachycardia (SVT). 40. Lessmeier TJ, 1996;19(1):95–106. / Vol. Cheng J, Application of a new algorithm in the differential diagnosis of wide QRS complex tachycardia. Pacing Clin Electrophysiol. Kim EM, J Am Coll Cardiol. Tischenko A, Pour l'épreuve écrite: Des sujets des années passées. 15. Roberts-Thomson KC, A Holter monitor or an event recorder is usually needed to capture the arrhythmia and confirm a diagnosis. Toutes les matières sont embarquées dans l'application : mathématiques, physique-chimie, histoire-géographie, philosophie, SVT, etc. Supraventricular tachycardia. Arch Intern Med. Rhythm was terminated with 6 mg of intravenous adenosine (Adenocard). ... Français Histoire Géographie Mathématiques SVT Physique-Chimie Espagnol Mentions légales. Symptoms may include palpitations (including possible pulsations in the neck), chest pain, fatigue, lightheadedness or dizziness, and dyspnea. Même site avec les sujets classés par partie et par thème (version numérique uniquement). Diagnostic electrophysiology confirmed the mechanism. Accelerated rhythms can be frightening to the patient if recurrent or persistent, and can cause significant morbidity. During an episode of SVT, the heart rate is at least 100 beats per minute but is usually closer to 150 beats per minute. Fox DJ, 2006;354(10):1044. Mechanisms of supraventricular tachycardia. DeStefano F, Atrioventricular dissociation is present, 4. P-wave morphology in focal atrial tachycardia: development of an algorithm to predict the anatomic site of origin. 22. Fermer. This example represents atrioventricular reciprocating tachycardia, which has a high cure rate with catheter ablation therapy. Patients with infrequent SVT episodes may only need pharmacotherapy on an intermittent basis, or what has been described as the “pill-in-the-pocket” approach.36 Those experiencing SVT not more than a few times per year, but with episodes lasting one hour or longer, may be treated using this approach. Table 2 lists symptoms associated with SVT. Supraventricular tachycardia. Ko JK, 1. For information about the SORT evidence rating system, go to https://www.aafp.org/afpsort.xml. 1990;322(24):1713–1717. Did symptoms begin when patient was sedentary or active? Verapamil, a negative inotrope, can result in relative bradycardia and vasodilation; care must be used if patients have a significant decrease in cardiac output.27 Neither digoxin nor a calcium channel blocker should be used in patients with Wolff-Parkinson-White syndrome or wide complex tachycardia, because these agents may enhance conduction down the accessory pathway, predisposing the patient to ventricular fibrillation.28 If the SVT persists, addition of a beta blocker will often result in its termination.29. Rodriguez LM, Cheng J, 2009;26(1):8–10. So the symptoms of SVT tend to appear out of nowhere and to disappear just as quickly. Increased sympathetic discharge may induce sinus tachycardia, Symptoms or arrhythmias after myocardial infarction or ischemia suggest ventricular origin. Fulton KL, In atrial tachycardia, the morphology and axis of the P wave are influenced by atrial site of origin and tachycardia mechanism. Krahn AD, Orejarena LA, Long-term therapy of paroxysmal supraventricular tachycardia: a randomized, double-blind comparison of digoxin, propranolol and verapamil. Address correspondence to Randall A. Colucci, DO, MPH, Ohio University College of Medicine, 255 Grosvenor Hall, Athens, OH 45701 (e-mail: Fuster V, / Journals Dhala A. Tomasi C, Miles W, ACC/AHA/ESC 2006 guidelines for the management of patients with atrial fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (writing committee to revise the 2001 guidelines for the management of patients with atrial fibrillation): developed in collaboration with the European Heart Rhythm Association and Heart Rhythm Society [published correction appears in Circulation. Une vidéo de méthode pour faire le point sur l'analyse de documents au bac S de SVT. It is unusual for supraventricular tachycardia to be caused by structurally abnormal hearts. A new approach to the differential diagnosis of a regular tachycardia with a wide QRS complex. Brugada P. Klein LS, J Am Coll Cardiol.   Enlarge Holdgate A, Kalman JM. Scheinman MM. Sujets d'écrit (tous les sujets depuis 2013). Strasburger JF, Kistler PM, Menozzi C, Paroxysmal supraventricular tachycardia (paroxysmal SVT) is an episodic condition with an abrupt onset and termination. Most common SVT (approximately 50 to60%)4 Occurs more often in younger women, Reentry caused by nodal pathways or tracts (two types): atypical (fast/slow) represents 10% and typical (slow/fast) represents 90% of all AVNRT, Rate: 118 to 264 bpm Rhythm: regular, narrow QRS complex (< 120 msec); regular, wide QRS complex (≥ 120 msec); may not see any P-wave activity in either type (atypical or typical) Atypical AVNRT: RP interval > PR interval; P waves negative in leads III and aVF Typical AVNRT: RP interval < PR interval; pseudo R wave in lead V1 with tachycardia, not with normal sinus rhythm; pseudo S wave in leads I, II, and aVF, Second most common SVT (approximately 30%)4,5 Orthodromic most common type (81 to 87%) Occurs more often in younger women and children May be comorbid with Wolff-Parkinson-White syndrome, Reentry caused by accessory pathways (two types): orthodromic (antegrade conduction through atrioventricular node) and antidromic (retrograde conduction through atrioventricular node), Rate: 124 to 256 bpm Rhythm: regular, narrow QRS complex common (orthodromic); regular, wide QRS complex uncommon (orthodromic or antidromic) if bundle branch block or aberrancy present Orthodromic AVRT: RP interval < PR interval or RP interval > PR interval with a slowly conducting accessory pathway; retrograde P waves (leads I, II, III, aVF, V1); delta wave seen with normal sinus rhythm, not with tachycardia Antidromic AVRT: short RP interval (< 100 msec); regular, wide QRS complex (≥ 120 msec); delta waves seen with normal sinus rhythm and tachycardia; concealed accessory pathways do not show delta waves, Third most common SVT (approximately 10%)6 Two types: AT and multifocal AT AT has two forms: focal and macroreentrant Multifocal AT occurs more often in middle age or in persons with heart failure or chronic obstructive pulmonary disease, Reentry (micro), automaticity, or triggered activity: focal AT (reentry, automaticity, or triggered activity); multifocal AT (automaticity activity), Rate: 100 to 250 bpm (atrial); ventricular varies Rhythm: regular, narrow QRS complex usually; irregular (ectopic foci) may have wide QRS complex if aberrancy present Focal AT: long RP interval most common; P-wave shape/polarity variable Multifocal AT: three different P-wave morphologies exist unrelated to each other; RR interval irregularly. Adenosine is the first-line medical treatment for the termination of paroxysmal SVT. Denman R, The most common types of supraventricular tachycardia are caused by a reentry phenomenon producing accelerated heart rates. A recent retrospective study showed that intravenous adenosine used in 197 patients with undifferentiated wide complex tachycardia was safe and effective for diagnostic and therapeutic purposes. In short RP tachycardias, atrial activity occurs with or shortly after ventricle excitation, and the P wave is found within the QRS complex or shortly after the QRS complex. This SVT is caused by accessory pathways (or bypass tracts) that serve as aberrant conduits for impulses that pass from the sinoatrial node and travel in an antegrade or retrograde fashion through such tracts, establishing a reentry circuit.11 AVRT, occasionally comorbid with Wolff-Parkinson-White syndrome, is a diagnosis not to be missed because this rhythm may spontaneously develop into atrial fibrillation.12 Key electrocardiography (ECG) findings, such as a delta wave, are not always apparent because of the accessory pathway being concealed; therefore, special diagnostic testing may be needed.13, The third most common type of SVT is AT (approximately 10 percent); it originates from a single atrial focus.6 This SVT, if focal, usually has a definitive localized origin, such as adjacent to the crista terminalis in the right atrium or the ostia of the pulmonary veins in the left atrium.14,15 Another form, multifocal AT, often occurs in patients with heart failure or chronic obstructive pulmonary disease.16. Ann Intern Med. Vidaillet H Jr, N Engl J Med. Role of radiofrequency ablation in the management of supraventricular arrhythmias: experience in 760 consecutive patients. J Am Coll Cardiol. Brugada P, Patient cannot tolerate medications or no longer wishes to use them, Patient has worsening symptoms or is becoming hemodynamically unstable Patient is in a high-risk occupation (e.g., pilot, truck driver, heavy equipment operator) or participates in high-risk recreational activities (e.g., rock climbing, sky or scuba diving), Physician is uncomfortable with or uncertain about management or initial diagnosis, Preexcitation is present on electrocardiography or if atrioventricular reciprocating tachycardia is suspected, Supraventricular tachycardia is accompanied by syncope, Wide QRS complex is present on electrocardiography. Supraventricular tachycardia (SVT) is a condition that causes your heart to beat much faster than it should. Pines JM. Goldberg AS, Benson DW Jr. Background. Am J Cardiol. 6ème 5ème 4ème 3ème 2nde Première Terminale. Katoh T, Larger trials comparing outcomes between these drug classes are not yet available (Table 8 22). Afterclasse te fait mémoriser ton cours à coup sûr ! Johnson-Liddon V, ; Different types of SVT arise from or are propagated by the atria or AV node, typically producing a narrow-complex … Jpn Circ J. Orejarena LA, Sra J, Podczeck A, Breithardt G. Wijns W, Nonpharmacologic management typically uses maneuvers that increase vagal tone to decrease heart rate. Blomström-Lundqvist C, A new approach to the differential diagnosis of a regular tachycardia with a wide QRS complex. Compared with narrow complex tachycardia, wide complex tachycardia presents infrequently, but does occur under certain conditions. Afterclasse Premium. 2001;37(2):548–553. Agents used for long-term pharmacotherapy are similar to those used to terminate the SVT during short-term management. Roberts-Thomson KC, afpserv@aafp.org for copyright questions and/or permission requests. Efficacy and safety of out-of-hospital self-administered single-dose oral drug treatment in the management of infrequent, well-tolerated paroxysmal supraventricular tachycardia. Gamperling D, 21. Focal atrial tachycardia II: management. Ko JK, Circulation. Patient information: See related handout on supraventricular tachycardia, written by the authors of this article. The term “SVT” is commonly used synonymously with atrioventricular-nodal-reentry tachycardia (AVNRT). Am J Cardiol. Kay GN, Rydén LE, Fermer. Comparison of the efficacy and safety of esmolol, a short-acting beta blocker, with placebo in the treatment of supraventricular tachyarrhythmias. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances. Vereckei A, Blanck Z, Adenosine versus intravenous calcium channel antagonists for the treatment of supraventricular tachycardia in adults. Szénási G, Prolonged and persistent elevated heart rates produced by some types of SVT have been known to cause a type of cardiomyopathy; therefore, a high index of suspicion for the diagnosis is important.18. Prénom. Diagnosis is often delayed because of the misdiagnosis of anxiety or panic disorder. Adenosine for paroxysmal supraventricular tachycardia: dose ranging and comparison with verapamil. 2002;89(9):1120–1123. Scheinman MM.