Torsades de pointes: A case with multiple variables

Torsades de Pointes: A Case With Multiple Variables IJAZ A. KHAN, MD, MOE T. WIN, MD, ARVIND J. BALI, ME), BALENDU C. VASAVADA, MD, TERRENCE J. SACCHI, MD Torsades de pointes is a polymorphic ventricular tachycardia that displays a unique electrocardiographic feature of twisting of the mean electrical axis of QRS complexes around an isoelectric line on the surface electrocardiogram. It is associated with long QT syndrome and has many precipitating mechanisms, etiologic factors, and treatment options. This report presents a case of torsades de pointes that was precipitated by multiple factors and required many treatment modalities. The patient in this case exhibited features of both congenital and acquired types of long QT syndrome. (Am J Emerg Med 1999;17:80-85. Copyright © 1999 by W.B, Saunders Company) Torsades de pointes (torsades) is a specific type of polymorphic ventricular tachycardia, 1 associated with prolonged QT interval and characterized by twisting of the mean electrical axis of the QRS complexes around an isoelectric line on the surface electrocardiogram (ECG). It has a tendency to terminate and recur spontaneously, and although it can degenerate into ventricular fibrillation and may cause death, 2 it usually remains asymptomatic or causes presyncope and related symptoms. Congenital idiopathic long QT syndrome, bradycardia, electrolyte imbalance, and drugs that prolong the QT interval are among the major etiologies. A case of torsades is presented that was precipitated by cocaine smoking in a patient with congenital idiopathic long QT syndrome. The torsades continually recurred because of underlying bradycardia, hypomagnesemia, and hypokalemia.

CASE REPORT A 37-year-old HIV-positive man with a history of cocaine and alcohol abuse was admitted to the hospital because he had been experiencing repeated episodes of syncope for 3 days. His history of heavy cocaine smoking preceded the first episode of syncope. He denied any history of previous syncope or any symptoms suggestive of organic heart disease. He was not taking any medications. There was no history of syncope or sudden cardiac death in the family. The patient was alert and oriented on arrival at the emergency department (ED). The physical examination was unremarkable except for bradycardia. Initial ECG revealed sinus rhythm with a heart rate of 38 beats/min, a QT interval of 711 msec, a QTo interval of 565 msec, and prominent U waves (Figure 1). No old ECG was available for comparison. Shortly after, frequent

From the Department of Medicine, Division of Cardiology, Long Island College Hospital, Brooklyn, NY. Manuscript received July 9, 1997, returned July 21, 1997; revision receivedAugust 1,1997, accepted September 4, 1997. Address reprint requeststo Dr Khan, 12 Vogel Loop, Staten Island, NY 10314. Key Words: Torsades de pointes, long QT syndrome, cocaine, bradycardia, hypomagnesemia,hypokalemia,HIV disease. Copyright © 1999 by W.B. Saunders Company 0735-6757/99/1701-0025510.0(3/0 80

premature ventricular contractions (PVCs) were seen on the monitor, followed by a short episode of torsades (Figure 2) that converted m sinus rhythm spontaneously. A bolus of 2 g magnesium was administered intravenously and a ContinUous infusion of magnesium was started. Initial laboratory examination subsequently revealed hypomagnesemia (magnesium level. 1.0 mEqFL). Three hours later, while still receiving the intravenous magnesium infusion, the patient developed an episode of pulseless torsades that was treated by immediate cardioversion. Another bolus of 2 g magnesmm was given, and an ECG showed normal sinus rhythm with a rate of 52 beats/min, a QT of 677 msec, a QTc of 636 msec. and prominent U waves (Figure 3). Repeat laboratory examination showed normal serum electrolyte levels. At that point, an isoproterenol infusion was begun to increase the patient's heart rate. His heart rate increased to 80 beats/min, and an ECG then showed a QT of 407 msec, a QTc of 469 msec, and prominent U waves (Figure 4). Another laboratory examination showed hypomagnesemia (magnesium level, 1.4 mEq/L) and hypokalemia (potassium level, 3.2 m E @ ) , which were corrected intravenously. A total of 14 g magnesium was transfused. The isoproterenol infusion was discontinued. The patient did not develop any further episodes of torsades for 2 days and was discharged. His ECG before discharge showed a rate of 56 beats/rain, a QT of 524 msec, and a QTc of 506 msec. All electrolyte levels were within normal limits. He was advised to abstain from cocaine abuse. At 5-week follow-up, he was asymptomatic and his electrolyte levels were normal. An ECG then showed normal sinus rhythm with rate of 56 beats/min, a QT of 502 msec, and a QTc of 484 msec (Figure 5). Two months after discharge, the patient was readmitted for recurrent syncopal episodes that were followed by cocaine smoking 1 day before admission. It is important to note that he denied any cocaine smoking between these two admissions. On arrival at the ED, he was conscious but lethargic and his physical examination was unremarkable except for bradycardia. An ECG showed sinus bradycardia and long QT and QTo intervals. The initial laboratory results were within normal limits except for hypomagnesemia (magnesium level, 1.0 mEq/L). Frequent PVCs were noted on monitor shortly after his arrival at the ED. Soon after, the PVCs were followed by short-long-short cycles (Figure 6), which were subsequently followed by torsades that reverted to sinus rhythm with a precordial thump. A l-rag magnesium bolus was given, followed by continuous intravenous infusion. The next day, while the patient was still receiving the intravenous infusion of magnesium, the torsades recurred. At that point, an isoproterenol infusion was added to his regimen and was titrated to the heart rate of 90 beats/min. On the third day, his heart rate began to decrease despite progressive increments in the rate of the isoproterenol infusion, and eventually his heart rate decreased to 50 beats/min. Multiple episodes of pulseless torsades recurred in succession, which were treated according to advanced cardiac life support (ACLS) protocol requiring cardioversion four times. A transvenous temporary pacemaker was placed and was set a rate of 90 beats/min. Isoproterenol was then discontinued, but magnesium infusion was continued. The next few days were uneventful. A permanent pacemaker was placed before discharge. The patient was asymptomatic at 3-month follow-up.

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DISCUSSION

Torsades de Pointes and Long QT Syndrome

Etiology of Torsades de Pointes and Long QT Syndrome

Torsades de pointes is a characteristic type of polymorphic ventricular tachycardia. The criteria for the diagnosis of torsades consist of (1) progressive twisting of p01arity of the QRS complex around an imaginary baseline on surface ECG, (2) complete 180 ° twist of QRS complexes in 10 to 12 beats, and (3) markedly prolonged QT interval in the last sinus beat preceding the onset of torsades. 3 The heart rate fluctuates between 200 to 250 beats/rain during the episode. Usually, torsades terminates spontaneously, but it has a tendency to recur in rapid succession within a short time and degenerate into ventricular fibrillation, causing sudden cardiac death. This is an important example of sudden cardiac death in an anatomically normal heart. The frequency of syncope and cardiac death varies from family to family. In congenital cases, torsades usually manifests in childhood, but its initial manifestation may occur at any age. Females are more prone to develop this arrhythmia; however, there is no definite explanation for this sex preponderance. 4 It usually produces a few hemodynamic disturbances because it is often short-lived and self-terminating; however, a prolonged episode may produce syncope. The torsades is associated with a prolonged QT interval on surface ECG called long QT syndrome. Along with the prolonged QT interval, this syndrome may present with other electrocardiographic features, including increased QT dispersion, prominent U waves, and abnormalities in T wave morphology. An unusual but diagnostic feature of the long QT syndrome is T wave alternans, in which the amplitude of the T wave varies on a beat-to-beat basis. Another important feature in some cases of the congenital long QT syndrome is sinus bradycardia and sinus pauses, 5 which may imply a particular

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The long QT syndrome has classically been divided into two broad categories, congenital and acquired. 6 The congenital long QT syndrome may be inherited or sporadic. Two well-characterized types of inherited long QT syndrome are Jervell Lange-Nielsen syndrome and Romano Ward syndrome. The Jervell Lange-Nielsen syndrome is inherited by autosomal recessive pattern and is associated with congenital deafness. The Romano Ward syndrome, which is more common than the Jervell Lange-Nielsen syndrome, is inherited by autosomal dominant pattern and is not associated with any deafness. These inherited syndromes usually manifest clinically in early childhood. The sporadic forms of congenital long QT syndrome appear to be more common than the inherited ones and may manifest clinically at any age. The acquired type of long QT syndrome is mostly secondary to drugs and electrolyte disturbances. Drugs are the most common cause of prolonged QT interval. The drugs most frequently prolonging the QT interval are mostly class Ia and class III antiarrhythmic agents including quinidine, procainamide, isopyramide, sotalol, ibutalide, and amiodatone. Quinidine is the most widely known antiarrhythmic drug that prolongs the QT interval; however, the incidence of the torsades with quinidine is not dose-related and it can occur at very low plasma levels of the drug, unlike with other QT interval prolonging drugs. On the other hand, amiodarone, although it markedly prolongs the QT interval, rarely causes torsades. The important noncardiac drugs that can prolong the QT interval and precipitate the torsades

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FIGURE 2. ECG tracing of the first episode of torsades de pointes demonstrating the twisting nature and varying morphologic appearances of the QRS complexes.

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include erythromycin, pentamidine, phenothiazines, tricyclic antidepressants, antihistamines (terfenadine and astemizole), intifungal agents (ketoconazole and itraconazole), and probucol. Cisapride v and adenosine s have also been reported to cause prolongation of the QT interval. Concomitant use of erythromycin, ketoconazole or itraconazole and terfenadine or astemizole has an additive effect on the prolongation of the QT interval and precipitation of torsades because these agents may competitively block the metabolism of each other in the liver. The electrolyte disturbances that prolong the QT interval are hypokalemia, hypomagnesemia, and hypocalcemia. Development of torsades is relatively rare, however, with hypoealcemia. Besides drugs and electrolyte disturbances, some other acquired causes of prolonged QT interval are subarachnoid hemorrhage, starvation, stringent dieting, organophosphoris insecticides, and cocaine. 9 Severe bradycardia of any etiology, including sick sinus syndrome and complete heart block, may precipitate torsades by prolonging the QT interval to a degree that may be greater than what would be expected merely from a slow rate. 1°31

FIGURE 4. ECG tracing while the patient was receiving isoproterenol infusion. The length of QT interval has decreased: QT is 407 msec and QT~ is 469 msec. Heart rate is 80 beats/rain but prominent U waves are still present.

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Mechanisms of Torsades de Pointes In the patients with long QT syndrome, the torsades may be precipitated by one of the two mechanisms that are "panse-dependent" and "adrenergic-dependent. ''5 Classically, in the acquired cases of the long QT syndrome, precipitation of the torsades is considered pause-dependent because it is precipitated by a pause in the electrical activity created by a longer cycle length that might be postextrasystolic or caused by bradycardia. This format of longer cycle length preceding the episode of torsades is called short-longshort sequence of the beats (Figure 2). 12 In a typical short-long-short sequence, a sinus beat is followed by an extrasystole (short cycle), the extrasystole is followed by a sinus beat after a long postextrasystolic pause (long cycle), and this sinus beat, which has a longer QT interval, is then followed by a ventricular extrasystole, which is the first beat of an episode of the torsades. Sometimes, multiple short-longshort sequences of increasing complexity precede the episode of torsades (Figure 6). On the other hand, in the

KHAN ET AL • TORSADES DE POINTES AND LONG QT SYNDROME

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FIGURE 5. Follow-up ECG obtained between the two admissions shows QT of 502 msec and QTc of 484 msec. Note the persistence of bradycardia. Electrolyte levels were normal when this ECG was obtained.

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nesemia and hypokelemia) long QT syndrome, and the cocaine was initial precipitating factor for the torsades, which continually recurred because of the underlying bradycardia, hypomagnesemia, and hypokalemia.

congenital cases of long QT syndrome the precipitation of torsades is considered adrenergic-dependent because torsades and sudden death have been associated with sudden intense adrenergic stimulation such as sudden exertion, delirium tremens, emotional stress, fright, anger, or startle. However, recent studies have shown that in the congenital cases the torsades may also be precipitated by the pause, 13 which seemed to be the case in our patient. In our patient, both adrenergic-dependent and pausedependent mechanisms overlapped in precipitating the torsades. Both of the times, torsades was precipitated by cocaine (an intense adrenergic stimulation) while the patient was bradycardic (pause). Cocaine inhibits central and peripheral neuronal catecholamine uptake, resulting in the accumulation of catecholamines, thereby causing intense stimulation of the sympathetic nervous system. ~4 This intense sympathetic stimulation produces inhomogenesities in the repolarization phase of action potential in the cardiac muscle. The existence of these repolarization inhomogenesities is one of the proposed electrophysiological mechanisms of the torsades. Another dominant feature in our patient's clinical presentation was persistent bradycardia that was a part of his sporadic congenital long QT syndrome. The congenital nature of long QT syndrome is evident from the ECG taken during the follow-up between his two admissions, which showed a normal sinus rhythm with rate of 56 beats/min, a QT of 502 msec, and QTc of 486 msec (Figure 5). No acquired etiology was found responsible for his long QT interval and bradycardia. His electrolyte levels were within normal limits, and he was not on any medications. During most of the course of both his hospitalizations, he remained bradycardic and frequently manifested short-long-short cycles. Therefore, we think this patient had both congenital (with-bradycardia type) and acquired (secondary to hypomagL e a ~ II

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Treatment of Torsades de Pointes and Long QT Syndrome Torsades de pointes is a life-threatening arrhythmia that requires immediate treatment. Most episodes of torsades are of short duration and terminate spontaneously, but longer episodes may cause marked hemodynamic compromise and may convert into ventricular fibrillation. In these situations, the treatment of choice is immediate cardioversion and implementation of other standard ACLS measures. ~5,16The most important step in the management of torsades is the treatment of the underlying etiology, which includes withdrawal of offending drugs and toxins, correction of underlying electrolyte deficiencies, and, in cases of sick sinus syndrome and complete heart block, implantation of a pacemaker. Along with correction of the underlying cause, further management of torsades de pointes and long QT syndrome can be divided into short-term and long-term treatments. Short-term treatment of torsades de pointes is required to prevent immediate recurrences of the arrhythmia in both congenital and acquired types of long QT syndrome. Shortterm treatment includes magnesium, temporary transvenous overdrive pacing, and isoproterenol. Intravenous administration of magnesium is very effective for suppression of torsades de pointes and is the treatment of choice for immediate management of this arrhythmia, in both types of long QT syndrome, even in patients with normal serum magnesium levels. 17 A single bolus of 2 g should be administered over a period of 2 to 3 minutes, followed by a T".............

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continued intravenous infusion at a rate of 2 to 4 mg/min. Repeat intravenous boluses may be given. Treatment with magnesium is very safe and should be initiated when the diagnosis is made. The only noticed side effect of magnesium is flushing sensations during the bolus injection. Interestingly, magnesium does not shorten the prolonged QT interval. It has no significant roll in the long-term management of the long QT syndrome. Temporary transvenous cardiac pacing at rates between 90 and 110 beats/min is another very effective short-term therapy for torsades 18 in both types of long QT syndrome and should be initiated if intravenous magnesium therapy fails to stop the recurrences of arrhythmia. Although pacing is effective irrespective of underlying heart rate, it is a particularly effective mode of therapy in bradycardia-dependent torsades. It increases heart rate, shortens the QT interval, and prevents long pauses. Insertion of a transvenous pacemaker requires specially trained medical personnel. Another mode of therapy available for the short-term management of torsades is isoproterenol. 19 It effectively controls the short-term recurrences of torsades in the bradycardia-dependent form of the syndrome by increasing the heart rate and shortening the QT interval. In these cases, isoproterenol may be used instead of transvenous pacing because it is easy to start, is more convenient, and does not require specially trained medical personnel. However, it is contraindicated in cases of congenital long QT syndrome without bradycardia because its adrenergic effects may further precipitate torsades. 2° It should be used as continuous intravenous infusion to maintain the heart rate at >90 beats/rain. The common side effects caused by isoproterenol are palpitations and flushing sensations. Because of its sympathomimatic properties, it should be used with caution in patients with underlying structural heart disease. Long-term treatment is often not required in the acquired cases of long QT syndrome because the QT interval normalizes after the etiology has been treated. On the other hand, long-term treatment of the congenital long QT syndrome is compulsory because the mortality rate of untreated patients approaches 50% within 10 years, which may be reduced to 3% to 4% with appropriate therapy. 5 The treatment options available for long-term management of the congenital forms of long QT syndrome are betaadrenergic blockers, permanent pacemaker implantation, left thoracic sympathectomy, and cardioverter-defibrillator implantation. Therapy with beta-adrenergic blockers is effective for the long-term management of the congenital long QT syndrome because the trigger for many life-threatening events in these cases is some form of adrenergic stimulation. Although effectiveness of the beta-blockers appears to be a class effect, propranolol is the most extensively used drug in these cases. It should be administered at dosage of 3 to 5 mg/kg/d. Beta-blockers are contraindicated in acquired cases because torsades can further be precipitated by the bradycardia produced by these agents. 2° Similarly, in the congenital cases in which bradycardia is a prominent feature of the syndrome, beta-blockers should not be used because the torsades may worsen due to beta-blockers which induce further decrease in the heart rate. In such cases, implantation of a permanent pacemaker is the first-line treatment. It is a very effective treatment for the congenital cases, especially

in those with bradycardia. Permanent pacing is a standard adjunct to beta-blockers in the patients who are symptomatic despite being on a full dose of beta-blockers. It is the treatment of choice in acquired cases of torsades de pointes due to bradycardia secondary to sick sinus syndrome and complete heart block. Permanent pacing decreases the QT interval by increasing the heart rate and prevents the long pauses in the electrical activity of the heart. Another highly effective mode of anti-adrenergic therapy for the congenital cases of long QT syndrome is high left thoracic sympathectomy:21 This is an option available for patients who are refractory to beta-blockers and pacing. The first four or five superior thoracic ganglia and the lower part of stellate ganglion are surgically ablated in this approach. A potential side effect may be the accidental ablation of the ocular sympathetic efferent nerves, resulting in the Homer syndrome. Rarely, in some cases of the congenital long QT syndrome, torsades recurs despite the combination therapy of beta-blockers, pacing, and left thoracic sympathectomy. In these cases, implantable cardioverter-defibrillator has been used successfully.22 Beta-blockers should be used along with the cardioverter-defibrillator device; otherwise, shocks from the device, by causing adrenergic stimulation, may further precipitate the torsades. The management of torsades in our patient was challenging because he exhibited the features of both the congenital and the acquired types of long QT syndrome and had many etiologies responsible for his arrhythmia. All electrolyte deficiencies were corrected by both intravenous and oral routes. Magnesium, which is considered very effective in controlling torsades even in patients with normal magnesium levels, was only partially effective. Likewise, isoproterenol controlled arrhythmia earlier but developed tachyphylaxis later. The patient continued to have torsades and needed multiple cardioversions. Eventually, a permanent pacemaker was implanted, and the patient was event-free on follow-up. SUMMARY

In summary, we presented an interesting case of torsades that manifested the features of both types of the long QT syndrome (congenital and acquired), had multiple predisposing factors (cocaine, bradycardia, hypomagnesemia, and hypokalemia), displayed both types of precipitating mechanism (adrenergic-dependent and pause-dependent), and received several known treatment modalities (abstinence of cocaine, electrolyte replacement, magnesium, isoproterenol, cardioversions, and permanent pacemaker placement) before becoming free of recurrent episodes of torsades de pointes. REFERENCES 1. Tzivoni D, Keren A, Stern S: Torsades de pointes versus polymorphous ventricular tachycardia. Am J Cardiol 1983;52:639640 2. Horowitz LN, Greenspan AM, Spielman SR, et al: Torsades de pointes: Electrophysiologic studies in patients without transient pharmacologic or metabolic abnormalities. Circulation 1981;63:11201128

KHAN ET AL [] TORSADES DE POINTES AND LONG QT SYNDROME

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12. Kay GN, Plumb VJ, Arciniegas JG, et al: Torsade de pointes: The tong-short initiating sequence and other clinical features: Observation in 32 patients. J Am Coil Cardio11983;2:806-817 13. Viskin S, Alia SR, Barron HV, et al: Mode of onset of torsade de pointes in congenital long QT syndrome. J Am Coil Cardio11996;28: 1262-1268 14. Billman GE. Cocaine: A review of its toxic actions on cardiac function. Crit Rev Toxicol 1995;25:113-132 15. Brady W, Meldon S, DeBahnke D: Prehospital polymorphic ventricular tachycardia. Ann Emerg Med 1993;22:1368 16. Brady W, Meldon S, DeBahnke D: Comparison of prehospital monomorphic and polymorphic ventricular tachycardia: Prevalence, response to therapy, and outcome. Ann Emerg Med 1995;25:64-70 17. Tzivoni D, Bani S, Schuger C, et al: Treatment of torsades de pointes with magnesium sulfate. Circulation 1988;77:392-397 18. Nguyen PT, Scheinman MM, Seger J. Polymorphic ventricular tachycardia: Clinical characterization, therapy, and the QT interval. Circulation 1986;74:340-349 19. Banai S, Tzivoni D. Drug therapy for torsade de pointes. J Cardiovasc Electrophysiol 1993;4:206-210 20. Roden DM. Torsade de pointes. Clin Cardiol 1993;16:683-686 21. Schwartz PJ, Locati EH, Moss AJ, et al. Left cardiac sympathetic denervation in the therapy of congenital long QT syndrome: A worldwide report. Circulation t 991 ;84:503-511 22. Gronefeld G, Holtgen R, Hohnloser SH. Implantable cardioverter defibrillator therapy in a patient with the idiopathic long QT syndrome. Pacing Clin Electrophysiol 1996;19:1260-1263