Clozapine-related Paroxysmal Supraventricular Tachycardia: a Case Report

Clozapine is considered to be more effective than other antipsychotic drugs for treating treatmentresistant schizophrenia. However, side effects of clozapine include agranulocytosis and, less commonly, cardiovascular disease, which is occasionally fatal. We describe a 56-year-old woman who developed clozapine-related paroxysmal supraventricular tachycardia during clozapine dose titration and had a recurrence despite being treated with verapamil. For treatment-resistant schizophrenia, a slow titration of the clozapine dose is necessary, and potential cardiac side-effects should be monitored.

Cervical ripening and induction of labor with misoprostol, dinoprostone gel, and a Foley catheter: a randomized trial of 3 techniques

OBJECTIVE

The purpose of this study was to compare the efficacy of 3 different techniques of cervical ripening and induction.

STUDY DESIGN

Patients who required cervical ripening and induction were randomized to one of 3 groups: (1) supracervical Foley catheter and intravaginal dinoprostone gel, (2) supracervical Foley catheter and 100 microg oral doses of misoprostol, or (3) serial 100-microg oral doses of misoprostol. Intravenous oxytocin was administered when a protraction disorder of labor was identified.

RESULTS

There were 339 women randomized. There was no significant difference in the time from first intervention to delivery in the 3 groups (P =.546). In each group, a similar percentage of women required oxytocin (P =.103). The rates of cesarean delivery were equivalent among the groups (P =.722). Rates of tachysystole were high but statistically equivalent among the 3 groups. There were no significant differences in Apgar scores or umbilical artery pH.

CONCLUSION

Oral 100 microg serial doses of misoprostol, with or without the use of a supracervical Foley catheter, were equivalent to the use of a supracervical Foley catheter and serial 4-mg doses of dinoprostone gel for cervical ripening and the induction of labor.

[Evaluation of hyperkinetic cardiac arrhythmia in chronic obstructive bronchopneumopathy]

Patients with chronic obstructive pulmonary disease (COPD), especially during acute exacerbations of their disease, show a greater incidence of cardiac arrhythmias than healthy subjects of the same age. The type of arrhythmias found may be supraventricular (premature atrial beats, paroxysmal supraventricular tachycardia, multifocal atrial tachycardia, atrial flutter, atrial fibrillation) or ventricular (premature ventricular beats, sustained ventricular tachycardia, torsades de pointes, ventricular fibrillation) that may lead to sudden cardiac death. The pathogenesis of arrhythmias is complex and many factors may be involved such as hypoxemia, hypercapnia, respiratory acidosis, metabolic and respiratory alchalosis, hypokalemia, concomitant ischemic heart disease, chronic cor pulmonale, left ventricular diastolic dysfunction. Remarkable attention has been drawn to the possible arrhythmogenic effect of drugs such as theophylline, beta-adrenergic stimulants and digitalis which are commonly used in the therapy of COPD. Both of the main classes of bronchodilators (methylxanthynes and beta-adrenergic agonists), even when used together, apparently do not increase the incidence of dangerous cardiac arrhythmias. However, these drugs should be used with caution in the elderly, in patients with preexisting cardiac arrhythmias, with heart disease or with reduced hepatic function. In these cases Holter monitoring, repeated measurements of plasma drugs concentration and prompt hospitalization of high risk patients in Intensive Care Unit may be needed.

[Amiodarone-induced hyperthyroidism causing progression of arrhythmia]

A case of a 38-year-old male with supraventricular paroxysmal tachycardia existing for more than a decade is reported. He has received amiodarone in a daily dose of 800 mg for three years and the tachycardia returned in 1992. New antiarrhythmic drugs were added but no beneficial effect has been achieved and moreover, a case of ventricular fibrillation occurred. The 12-lead ECG performed during tachycardia and the electrophysiological study showed orthodromic AV reentry tachycardia. Laboratory tests performed proved hyperthyreotic state. Attacks of paroxysmal tachycardia were returned and aggravated by the hyperthyreosis induced by amiodarone. Finally, antiarrhythmic drugs were discontinued and methimazol was introduced. Gradually, the patient become asymptomatic within two months. The most important conclusion of the case reported, that the amiodarone induced hyperthyreosis can be subclinical or obscure. Consequently, a regular control of serum thyreoid hormone levels at least twice a year on patients with long term amiodarone administration should be advised.

[Acute effects of propafenone in patients with ventricular pre-excitation]

PURPOSE

To evaluate the electrophysiological effects of intravenous propafenone in the anterograde and retrograde effective refractory period of the accessory pathways (AP), in patients with Wolff-Parkinson-White syndrome.

METHODS

Forty symptomatic patients were studied. All patients were undergone to electrophysiologic study at baseline and after IV propafenone (2.0mg/kg). Drug effects were analysed according to the basal state of the anterograde and retrograde effective refractory periods of the AP > < 270ms.

RESULTS

The mean anterograde and retrograde effective refractory periods of the AP were 275 +/- 76ms and 264 +/- 44ms at the control and 462 +/- 190ms and 438 +/- 184ms after drug respectively (p < 0.01 in both situations). The mean anterograde effective refractory period of the AV node was 236 +/- 40ms (control) and 276 +/- 57ms (post-drug)- p < 0.05. The mean atrial and right ventricular effective refractory period in the control were 210 +/- 23ms and 240 +/- 34ms passing to 215 +/- 24ms and 250 +/- 40 ms after drug respectively (p = ns). After drug, complete anterograde and retrograde block of the AP, occurred in 15 (42%) and 12 (35%) patients respectively. Out of 15 patients with complete anterograde block of the AP, 11 had anterograde effective refractory period of the AP > 270ms and 4, < 270ms (p < 0.02). Out of 12 patients with complete retrograde block of the AP after drug, 4 had retrograde effective refractory period > 270ms and 8, < 270ms (p: ns).

CONCLUSION

Propafenone caused significant increase in the anterograde and retrograde effective refractory periods of the AP. There was a tendency of the drug to show better effectiveness in patients with anterograde effective refractory period of the AP > 270ms. This results were not seen in relation to the retrograde effective refractory period of the AP.

Digoxin toxicity presenting as altered mental status in a patient with severe chronic obstructive lung disease

Gastrointestinal and cardiac manifestations are the commonly considered features of digoxin toxicity. This report describes a patient with severe chronic obstructive lung disease whose primary manifestation of digoxin toxicity is acute alteration of mental status. Neurologic dysfunction may be the sole manifestation of digitalis toxicity. The diagnosis of digoxin toxicity should be considered in elderly patients with altered mental status, even when serum levels are within a therapeutic range.

[Severe ventricular arrhythmia secondary to indapamide-induced hypopotassemia]

We report on two patients, treated with indapamide for mild hypertension, who developed life-threatening ventricular arrhythmias. The former showed severe hypokalemia, QT interval prolongation and "torsade de pointes": the latter, who suffered from ischemic heart disease, had slightly decreased serum potassium and ventricular fibrillation. In both cases no other cause accounting for hypokalemia and ventricular arrhythmia was found. Therefore we stress that serum potassium and ECG must be carefully monitored during indapamide therapy, mainly in patients with cardiac disease.

Role of intravenous isoproterenol in the electrophysiologic induction of atrioventricular node reentrant tachycardia in patients with dual atrioventricular node pathways

To assess the role of intravenous isoproterenol for the facilitation of electrophysiologic induction of atrioventricular (AV) node reentrant tachycardia, 20 patients with dual AV node pathways who lacked inducible AV node reentrant tachycardia at control study had a constant isoproterenol infusion administered and underwent repeat study. Six (30%) of 20 patients (group I) had inducible AV node reentrant tachycardia during isoproterenol infusion whereas the other 14 (70%) patients (group II) did not. Paroxysmal supraventricular tachycardia was clinically documented in all 6 group I patients compared to 3 (21%) of 14 group II patients (p = 0.002). The sensitivity and specificity of isoproterenol-facilitated induction of AV node reentrant tachycardia were 67 and 100%, respectively. The isoproterenol-facilitated induction of sustained AV node reentry was mediated by resolution of the weak link in anterograde slow pathway in 2 (33%) patients, in retrograde fast pathway in 3 (50%) and in both anterograde slow and retrograde fast pathways in 1 (17%) patient. Four group I patients were given intravenous propranolol, 0.2 mg/kg body weight, and had complete suppression of isoproterenol-facilitated induction of AV node reentry. Thus, intravenous isoproterenol is a rather sensitive and highly specific adjunct to electrophysiologic induction of AV node reentrant tachycardia in patients with dual AV node pathways but without inducible sustained AV node reentry.

[Study of spontaneous acetylcholine-dependent tachyarrhythmias using isolated specimens of the right canine atrium by bilateral mapping of the spread of excitation]

The authors examined tachycardias induced by administering acetylcholine (AC), 1-2 micrograms into the artery of sinus node (ASN) of an isolated specimen of the canine right atrium, which had spontaneous automatism. Bilateral multielectrode mapping was employed. The episodes of tachycardia occurred during AC-induced arrest of sinus rhythm. In 81% of the cases, episodes of arrhythmia consisted of 2-3 beats, in 19%, 6-150 beats. The mapping revealed a focal picture of activation during short-term episodes of arrhythmia and transition from a focal type of activation to the re-entry in most cases of "prolonged" episodes. With this, excitation circulation might be detected only on one side of the specimen, in the presence of the focal activation picture, on the other. Focus-re-entry transition is proposed to be caused by a mechanism associated with heterogeneous refractoriness of atrial tissue.

[Arrhythmogenic effect of anti-arrhythmia agents in patients with paroxysmal supraventricular reciprocal tachycardia]

A retrospective study of the results of consecutive testing of antiarrhythmic agents was carried out in 82 patients with paroxysmal reciprocal supraventricular tachycardia. Arrhythmogenic effects of anti-arrhythmic drugs were detected in 22 (6.1%) of 359 pharmacologic tests. The electrophysiologic basis of arrhythmogenic effect is delayed impulse conduction at some point of the blood flow pathway, conducive to the emergence or maintenance of the re-entry phenomenon.

Paroxysmal supraventricular tachycardia during treatment with cisplatin and etoposide combination

We report a case of a 60-year-old woman affected by squamous lung carcinoma, who developed paroxysmal supraventricular tachycardia during cisplatin and etoposide combination chemotherapy. Cisplatin toxicity on cardiac electrical activity is discussed. This observation might suggest caution when cisplatin is used in patients with cardiac disease or pretreated with other potential cardiotoxic antineoplastic agents.

Coronary hemodynamics in simulated paroxysms of ventricular tachycardia: role of myocardial impairment and of extravascular resistance

In 6 patients with healthy hearts (controls), 17 with coronary artery disease (CAD) and 6 with left ventricular hypertrophy due to aortic valvular disease, aortic pressure, coronary sinus blood flow (CSF) and lactate extraction were determined before and after the sudden onset of a paced ventricular tachycardia of 170 bpm (VT 170 = simulated paroxysmal ventricular tachycardia). Comparison to parameter changes during dipyridamol vasodilation revealed reduced coronary vascular reserve for CAD and hypertrophy. While VT induced a reduction of aortic pressure (stabilized by an average of 22%, and most excessively for CAD; p less than 0.05) and CSF remained at/or slightly above control levels (by an average of 31%; p greater than 0.05) equally for all groups (p greater than 0.05), lactate production in the groups with CAD and hypertrophy indicated myocardial impairment by ischemia. Excessively greater increases of CSF during dipyridamol vasodilation (vs. VT) for all groups suggested VTs extravascular resistance increase to have limited the extent of the potential of coronary vascular decrease. With one variable being kept constant (i.e. 'clamping' the vascular component of coronary resistance at its limit by dipyridamol), tachycardia during dipyridamol (D) vasodilation (VT 170+D and VT 140+D) in the controls and in the CAD group resulted in a linear decrease of CSF, allowing quantification of impaired coronary reserve for CAD. We concluded from the observations that: (1) paroxysmal VT demands fast therapeutic action foremost in the impaired myocardium, and (2) tachycardia per se acts as limiting factor for coronary blood flow via increase in extravascular resistance (aside from a shortened diastole).

Alterations in aortic pressure and coronary blood flow: their time sequences with induced paroxysms of ventricular tachycardia in normal and impaired myocardium

In an attempt to define more clearly the hemodynamic effects of paroxysmal tachycardia in their time sequence not only for the normal heart, we monitored coronary sinus flow (CSF), aortic mean pressure (AOMP), and coronary vascular resistance in 42 patients. They underwent stress testing of left ventricular function by paced ventricular tachycardia (VT 170/min); 13 patients had no heart disease (controls), 10 patients left ventricular hypertrophy, and 19 patients coronary artery disease (CAD). Up to the 6th s after the sudden start of VT, CSF was maintained during a 50% decrease in AOMP, while controls and hypertrophy patients with less pressure reduction (of 33 and 42%, respectively) showed a tendency to increase CSF. From the 12th to the 26th s of VT, a slight recovery of the low AOMP values took place, while CSF remained at or slightly below baseline levels. The steady state VT was characterized by further improved pressures and a CSF slightly above baseline even in CAD. Up to the 12th s after sudden stop of VT, aortic systolic pressure showed a steep increase (by 17, 13, and 8% for the three groups, respectively), while CSF dropped temporarily and after an upswing between the 12th and 26th s reached baseline levels together with AOMP. We conclude: (1) The rapidity of coronary response and its initial lag after changes of perfusion pressure are similar for normal and impaired myocardium; slight differences exist in quantity. (2) While with VT initiation perfusion pressure drops precipitously, CSF is maintained at baseline levels or slightly below even in CAD. (3) The quality of coronary hemodynamic adaptation to tachycardiac paroxysms in the impaired myocardium warrants the presence of additional operative mechanisms other than a reduced reduction in coronary vascular reserve capacity known in CAD and left ventricular hypertrophy.

Dopamine-induced paroxysmal supraventricular tachycardia in an infant

Dopamine is an effective inotropic agent in the management of circulatory collapse. Ventricular dysrhythmias are reported to occur during dopamine infusion. The following report describes an infant with circulatory failure who experienced an episode of paroxysmal supraventricular tachycardia while receiving dopamine. Instability or immaturity of the cardiac conduction system during early infancy may contribute to the induction of an arrhythmia of supraventricular origin.

Effects of oral disopyramide phosphate on induction of paroxysmal supraventricular tachycardia

The effects of oral disopyramide phosphate on laboratory induction of paroxysmal supraventricular tachycardia (PSVT) were studied in 16 patients with clinical PSVT. After control electrophysiologic study to determine the inducibility and mechanism of PSVT, patients were given 200-300 mg (275 +/- 45 mg, mean +/- SD) of disopyramide for three to five doses over 24 hours and were then restudied. All patients had inducible, sustained PSVT during the control study. After disopyramide, PSVT was noninducible in eight patients (50%), including six of nine with atrioventricular nodal reentrance and two of seven with atrioventricular reentrance; inducible but nonsustained in two (12.5%) (both with atrioventricular reentrance); and inducible and sustained in six (37.5%). The benefit of disopyramide seemed predominantly to reflect depression of conduction in the retrograde limb of the circus movements, although effects upon the antegrade limb were also observed. In the eight patients with inducible PSVT before and after disopyramide, tachycardia cycle length increased from 348 +/- 33 to 404 +/- 29 msec (mean +/- SEM) (p less than 0.001). These results suggest that disopyramide would be effective in preventing recurrence of clinical PSVT in selected patients.

Effects of verapamil on supraventricular tachycardia in patients with overt and concealed Wolff-Parkinson-White syndrome

Verapamil (0.15 mg/kg) intravenously, was administered to 19 patients with recurrent supraventricular tachycardia (SVT) undergoing electrophysiological evaluation. Twelve patients had overt Wolff-Parkinson-White (WPW) syndrome and seven patients had concealed accessory pathways conducting in the retrograde direction only. Verapamil had a significant effect in delaying conduction and prolonging refractoriness in the atrioventricular (AV) node, but no significant actions on any of the other cardiac tissues that formed the tachycardia circuit in these patients. In particular, it had no significant effects on anterograde or retrograde bypass conduction or refractoriness. Sustained SVT was initiated in 15 patients, and was terminated within 60 to 105 seconds of a 30-second injection of verapamil in 13 patients. Cycle length alternation during SVT was seen in six patients prior to reversion, and spontaneous ventricular complexes (VPCs) were observed following verapamil administration in five patients. Two patients with apparently normal sinus node function showed prolongation of their sinus node recovery times immediately following reversion of SVT by verapamil. Echo zones were assessed before and after verapamil, and sustained or self-terminating SVT could still be induced after the drug in 13 of the 15 patients who had sustained SVT beforehand. It was concluded that intravenous verapamil was effective in terminating sustained SVT in the majority of patients with overt or concealed WPW and that, despite a potential for sinus node depression and the initiation of VPCs, it had no clinically significant side effects. The ability to reinitiate SVT following its administration suggests the need for immediate follow-up with maintenance drug therapy.

[Electrophysiologic actions of mexiletine (Kö-1173) in man]

Electrophysiologic studies have been performed in 11 patients before and 12 minutes after intravenous administration of 250 mg of mexiletine. All patients had crisis of paroxysmal tachycardia. The cases with conduction defects at any level, as ascertained by surface ECG or basal electrophysiologic recordings, were excluded from treatment. The results obtained do not show significant variations in any of the parameters studied. It is concluded that mexiletine is an antiarrhythmic drug with an action typical of group I of the classification of Vaughan Williams, and that it reduces the maximum velocity of systolic depolarization. In the absence of conduction defects, its behaviour is similar to that of lidocaine or diphenylhydantoin.

Disopyramide-induced ventricular fibrillation

Three cases are described with documented ventricular fibrillation shortly after the patients received disopyramide in moderate dosage. Electrocardiograms showed markedly prolonged Q-T intervals in two patients and a prominent U wave with a prolonged Q-U interval in one patient, but no change in QRS width. Disopyramide-induced ventricular fibrillation appears to be similar to that caused by quinidine and is an indication to discontinue the drug.

Effects of atropine on induction and maintenance of atrioventricular nodal reentrant tachycardia

The electrophysiologic effects of atropine were studied in 14 patients with dual atrioventricular (AV) nodal pathways and recurrent paroxysmal supraventricular tachycardia (PSVT). During PSVT, all patients used a slow pathway (SP) for antegrade and fast pathway (FP) for retrograde conduction. Atropine enhanced both SP antegrade and FP retrograde conduction, shown by a decrease in paced cycle lengths (atrial and ventricular) producing AV and ventriculoatrial block. Five patients had induction of sustained PSVT before and after atropine. Seven patients failed to induce or sustain PSVT before atropine, because of retrograde FP refractoriness. All seven had induction of sustained PSVT after atropine due to facilitation of FP retrograde conduction. Two patients had only single atrial echoes before atropine, reflecting SP antegrade refractoriness. After atropine, sustained PSVT was inducible in one, and nonsustained in the other, PSVT cycle length could be compared in seven patients before and after atropine and decreased from 383 +/- 25 to 336 +/- 17 (p less than 0.05). Thus, in patients with dual AV nodal pathways, atropine facilitated SP antegrade and FP retrograde conduction, shortened cycle length of PSVT and potentiated ability to sustain PSVT.

Alternation of atrial cycle length in supraventricular tachycardia

Nine cases of alternation of the atrial cycles during supraventricular tachycardia are presented, three of which were manifestly due to digitalis toxicity. They presented the following features: absence of 1/1 conduction, upright P waves in Lead II, atrial rates of 156-218. When alternation disappeared, the atrium adopted the longest of the previously inscribed cycles. A ventriculophasic cause was excluded. The possible mechanisms are discussed in terms of the known functional anatomy of the various forms of SVT.

Paroxysmal supraventricular tachycardia during theophylline therapy in a premature infant

An episode of supraventricular tachycardia occurred in an infant born at 31 weeks' gestation after three days of therapy with theophylline 3.5 mg/kg every six hours. The infant had a plasma theophylline half-life of 24.7 hours and a low plasma theophylline clearance of 12.7 ml/kg/hour. The plasma theophylline concentration at the time of the arrhythmia was about 42 mg/l. The extent of drug accumulation with these kinetic characteristics is emphasized. Serious adverse effects due to theophylline may occur with few signs of symptoms of impending toxicity. Plasma theophylline concentration measurements are valuable in avoiding such toxicity.

A case showing atrial dissociation and other various kinds of arrhythmias

A case is reported in which atrial dissociation occurred after oral isoproterenol administration to increase the heart rate in the presence of complete atrioventricular block. Two types of P wave, one with small upward deflection and the other with deep downward spike-like deflection, were present. The latter wave appeared at a high rate of 300/min, suggesting the existence of atrial flutter in the left atrium alone.

Theophylline bioavailability following oral administration of six sustained-release preparations

Plasma theophylline concentrations were measured in 20 adults after single doses of 8 mg/kg of each of six oral sustained-release theophylline preparations. Twelve subjects were studied in a multiple-dose trial. Comparison of bioavailability and absorption characteristics suggest usefulness of some of these products for the purpose of maintaining safe and effective blood levels with twice-a-day dosing.

[Paroxysmal ventricular tachycardias complicated with Adams-Stokes syndrome during lidoflazin treatment (author's transl)]

A case is reported of ventricular extrasystole occurring during Lidoflazin treatment. It is considered that Lidoflazin is an effective pharmacon, but that it may enhance the ventricular irritability. Attention is drawn to the necessity of the frequent control of Lidoflazin-treated patients.

Chronotropic effect of acetylstrophanthidin infusion into the canine sinus nodal artery

Studies were performed to determine the chronotropic effect of acetylstrophanthidin during constant infusion through cannulation of the sinus nodal artery. Ten mongrel dogs weighing 13.5 to 18 kg were studied under sodium thiamylal anesthesia. Epicardial atrial and ventricular electrograms were recorded. The sinus nodal artery was cannulated and infused for 20 minutes at a rate of 2 cc/min with a solution containing acetylstrophanthidin, 0.5 microng/cc. Mean results for the group of 10 animals were determined. There was a gradual acceleration of the atrial rate of 45 beats/min after 6 to 8 minutes of infusion. The peak atrial rate of 175 beats/min was achieved by 10 to 12 minutes. This tachycardia persisted for 2 to 4 minutes without atrioventricular block or premature beats. By 12 to 14 minutes, there was a gradual slowing of atrial rate followed by bradycardia, sinus pauses and atrial arrest. Sinus nodal arterial infusion of acetylstrophanthidin produces an initial positive chronotropic effect and, if maintained, a depression of atrial rate and, terminally, atrial arrest. The gradual time course of development and decline of the tachycardia suggests that the "paroxysmal" atrial tachycardia caused by digitalis excess is the result of enhanced pacemaker automatically rather than reentry, and thus is not truly paroxysmal.

Simultaneous atrial and A-V junctional tachycardia

Three cases of simultaneous atrial and a-v junctional tachycardia, related to the administration of digitalis and occurring in a short period of 16 months, are reported. Severe myocardial damage, anoxia and shock may decrease markedly the tolerance of the myocardium to digitalis, and thus predispose to the occurrence of simultaneous atrial and a-v junctional tachycardia.

Caffeine intoxication: a case of paroxysmal atrial tachycardia

Caffeinism is a syndrome resulting from the excessive ingestion of caffeine and characterized primarily by cardiovascular and central nervous system manifestations. A variety of tachyarrhythmias and extrasystoles are believed to reflect the toxic, cardiotonic effects of caffeine. A case of paroxysmal atrial tachycardia (PAT) related to caffeine abuse is PAT. The importance of considering this and other less frequent conditions as potential causes for this arrhythmia is stressed.

Sinoatrial block during lithium treatment

Lithium is known to produce T wave changes in the ECG, whereas effect upon the conducting system of the heart has not been described. In our patient lithium produced sinoauricular block and possibly tachycardia. The correlation between lithium treatment and tachyarrhythmias is discussed. When during lithium treatment block is found, the treatment should preferably be stopped, but if this is not possible it is important to realize that digitalis should not be used as a prophylactic drug against tachycardia, as it worsens the block and therefore increases the frequency of arrhythmia, even leading to Adams-Stokes attacks.

Digitalis and atrial tachycardia with block

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