Effect of tamoxifen on GH and IGF-1 serum level in stage I-II breast cancer patients

OBJECTIVE

Tamoxifen suppresses insulin-like growth factor-1 (IGF-1) plasma levels in early and advanced breast cancer patients. Relationships between tamoxifen (GH) and IGF-1 are complex and not completely described yet. The present investigation was performed to evaluate the effect of acute and chronic tamoxifen administration on GH response to growth hormone-releasing hormone (GHRH), as well as on IGF-1 serum levels.

MATERIALS AND METHODS

Evaluation of GH after administration of GHRH was performed (a) at baseline, (b) 3 hours after 20 mg oral administration of tamoxifen and (c) after 12 weeks of 20 mg a day oral tamoxifen treatment, in fifteen postmenopausal stage I-II breast cancer patients. IGF-I was measured at baseline and after chronic tamoxifen administration.

RESULTS

The GH response to GHRH was significantly reduced after 12 weeks of tamoxifen 10 mg administered twice a day orally (mean peak 3.2 +/- 0.2 micrograms/l, mean AUC 261.3 +/- 18.2 micrograms/minute p < 0.01 versus basal AUC). A concomitant significant reduction of IGF-1 was observed after 3 months of tamoxifen treatment. Basal pretreatment levels of 113.2 +/- 15.5 micrograms/l were suppressed to 70 +/- 7.9 micrograms/l (p < 0.01).

CONCLUSION

Our study confirm the inhibitory effect of tamoxifen on IGF-I and suggested, as shown in previous in vitro data, that its suppression could be directly related to GH reduction in response to GHRH stimulation.

[Anatomopathological and biochemical correlation of lesions produced by standard and irrigated 4 mm radiofrequency catheters]

INTRODUCTION AND OBJECTIVES

The influence on the size of radiofrequency lesions by cooling of the tip of the electrode remains unclear. Moreover, the possible effects of two different cooling systems, closed and open, have not been well differentiated. We designed this study to compare both systems of irrigated-tip catheters and the lesions produced with standard 4 mm catheters and also to evaluate the pathological and biochemical marker release correlation (cardiac troponin I) in an experimental model.

METHODS

The study was performed in 20 pigs. Applying between 1-8 radiofrequency pulses, at a power of 15, 25 or 50 watts, for 15-60 seconds to each animal. After 7 days, the pigs were sacrificed for anatomopathological study.

RESULTS

A total of 54 lesions were produced, 25 with standard catheters and 29 with irrigated catheters. The mean volume of the lesions produced with standard catheters was 146 +/- 110 microl and with irrigated-tip catheters 856 +/- 864 microl (p < 0.001). Peak values of cardiac troponin I were also higher for irrigated catheters (18 +/- 15 ng/ml) than for standard (6.5 +/- 3 ng/ml). The correlation between the size of the lesion and the levels of cardiac troponin I were 0.86 and 0.79 with the standard and irrigated-tip catheters, respectively. The incidence of cratering was higher with standard catheters (60%) than with irrigated (27%).

CONCLUSIONS

The lesions produced with an irrigated catheter are greater than those observed with standard catheters. The mean peak value of postablation cardiac troponin demonstrate a good correlation with the real size of the necrosis.

A prospective multicenter study on the safety of a pacemaker with automatic energy control: influence of the electrical factor on chronic stimulation threshold. PEACE Investigators

The effectiveness and safety of a pacemaker with automatic control of capture was evaluated in 162 patients followed at 27 Spanish centers. The aim of our prospective, multicenter, and randomized trial was to determine the relationship between the voltage output of the pulse generator and the stimulation threshold. We randomized 162 patients (107 men, mean age 75 +/- 12 years). We implanted a ventricular pacemaker model Regency SR+ or SC+ with Pacesetter's low polarization bipolar leads Membrane E 1450. The patients were randomized to receive Autocapture or not; group I (81 patients) Autocapture On, pulse output automatically adjusted and group II (81 patients) Autocapture Off, fixed output parameters (3.9 V, 0.37 ms). We performed a 6-month follow-up measuring stimulation threshold by means of the VARIO test and Autocapture test, evoked response signal, and R wave signal. The mean R wave was 15.77 +/- 3.5 mV at the end of the follow-up for group I, and 14.91 +/- 6.8 mV for group II (P = NS). The measured evoked response at the end of the follow-up was 9.25 mV in Group I and 8.48 mV in Group II (P = NS). The stimulation threshold was not different between groups. The current density created with the voltage and pulse width used in this study (< or = 3.9 V and 0.37 ms) at the tip of this electrode during the maturation process had no influence on the development of the chronic detection and stimulation thresholds.

[Recurrent ventricular fibrillation during a febrile illness in a patient with the Brugada syndrome]

Different situations have been involved in the origin of ventricular arrhythmic events in patients with the Brugada syndrome such as bradycardia, alcohol consumption and mental stress. We present a 30 year old male with recurrent ventricular fibrillation due to a febrile illness with intense sweating. He had been previously studied at our Unit in 1995 because of an episode of resuscitated cardiac arrest due to ventricular fibrillation. The twelve-lead electrocardiogram showed the typical characteristics of a patient with the Brugada syndrome. Different invasive and non-invasive tests performed were normal. He received a defibrillator and had no recurrences during 4 years of follow up. In March,1999, after an upper respiratory tract infection he had high fever treated with paracetamol but at down he had sweating and chills, followed by 3 defibrillator shocks. Late interrogation showed 5 episodes of ventricular fibrillation, two of them non-sustained, and the rest adequately treated by the defibrillator. Activation and inactivation kinetics for early INa are twofold faster at higher temperature, and shift activation and steady-state inactivation. This may explain the role of the temperature as a trigger for ventricular arrhythmias in our patient.

Biochemical markers and cardiac troponin I release after radiofrequency catheter ablation: approach to size of necrosis

BACKGROUND

We designed this study to determine the value of serum levels of several cardiac markers in patients who underwent radiofrequency ablation and to establish the utility of cardiac troponin I (cTnI). After radiofrequency ablation there is always a small localized endomyocardial necrosis. The volume of the necrosis may be estimated by the rise of several biochemical marker levels, classically creatinine kinase (CK) and CK-MB. cTnI is a newly available biochemical marker with a high cardiac specificity.

METHODS AND RESULTS

We analyzed the data from 51 patients who underwent radiofrequency ablation and from 16 control patients who underwent an electrophysiologic study without ablation. The levels of CK, CK-MB mass, cTnI, and myoglobin were compared with clinical findings, ST-T wave abnormalities, and the presence of arrhythmias. The study shows that there is a higher release of cTnI compared with the standard markers CK, CK-MB, and myoglobin. A pathologic value of cTnI was found in 92% of the patients of the ablation group. CK-MB had a lower sensitivity (63%). The area under the receiver operating characteristic curve for cTnI was 0.9375, significantly superior to the other biochemical markers (P <.05). We found a moderate level of correlation between the number of radiofrequency pulses and cardiac cTnI release (r = 0.69, P <.0001).

CONCLUSIONS

The serum level of cTnI detects the minor myocardial damage produced by radiofrequency ablation. This would be useful information to have in patients who might have the potential for other ischemic events. The other biochemical or ablation parameters usually reported, including the radiofrequency ablation parameters, have no good correlation with the size of the myocardial necrosis. Therefore we suggest that monitoring of cTnI is the best way to detect and quantify the size of myocardial necrosis created by radiofrequency ablation.

Cardiac troponin I and minor cardiac damage: biochemical markers in a clinical model of myocardial lesions

Radiofrequency (RF) catheter ablation is the curative treatment of choice for many cardiac arrhythmias. After RF ablation there is always a small localized endomyocardial necrosis, necessary to abolish the arrhythmia. We designed this study to determine the serum concentrations of several cardiac markers in patients who underwent RF catheter ablation. The study shows a higher frequency of increase of serum cardiac troponin I (cTnI) than of creatine kinase (CK), the CK MB isoenzyme (CK-MB), or myoglobin. A pathological value of cTnI was found in 47 of 51 patients (92%) in the ablation group. The area under the ROC curve for cTnI was 0.9375, significantly higher than for the other biochemical markers (0.86, 0.76, and 0.75 for CK-MB, myoglobin, and CK, respectively), with P <0.05. We conclude that the serum concentration of cTnI is the best biochemical marker for detecting the minor myocardial damage produced by RF ablation.

[Electromagnetic interference between automatic defibrillators and digital and analog cellular telephones]

BACKGROUND AND OBJECTIVES

Functional pacemaker interference by mobile telephones has been described with analogical systems and with possible greater influence, digital systems, including inhibition and inadequate pacing. The influence of both system has not been extensively studied in patients with implantable cardioverter defibrillators (ICD).

PATIENTS AND METHODS

We studied the influence of mobile phones, both digital and analogic network, on the performance of several models of defibrillators, in a standardised test set up designed to provide high sensitivity. The purpose of our study was to establish whether there are any influences on ICD functions, both in in vivo and in in vitro models. Several mobile phones, with different transmission powers, were moved towards the defibrillator and the electrode, under continuous documentation of defibrillator sensing and interrogation afterwards. The experimental model was performed with the aid of an arrhythmia simulator (Intersim) and demo-defibrillators. The tests were repeated both in and out of a solution of saline water with an impedance within normal human limits.

RESULTS

Partial loss of telemetry was found in 14 patients, 8 with analogical phones and 6 with digital phones. Fourteen patients showed alterations only on the surface electrocardiogram channel and five on the intracavitary channel. The same results were reproduced in the in vitro model. However, the in vitro test allowed us to simulate multiple ventricular arrhythmias, and demonstrate the normal sensing and functioning of the defibrillator during a "spontaneous" arrhythmia. After testing, we demonstrate that no real oversensing/undersensing was documented in any device. There was no evidence of ICD reprogramming or pacing inhibition. In particular, no inadequate therapies were delivered.

CONCLUSIONS

a) in our series, we have not demonstrated clinically significant electromagnetic interferences with mobile phones of digital or analogical networks: b) the in vitro model allowed us to conclude that even if a spontaneous arrhythmia appears, the function of the defibrillator is not altered; c) the use of mobile phones seems to be safe for defibrillator patients, and d) however, some basic rules, such as to maintain the phone at least 15 cm away from the defibrillator, are advised.

[National Registry of Automatic Implantable Defibrillators in 1996]

The results of the Spanish Registry of Automatic Defibrillators implanted between February 1996 and January 1997 are reported. A questionnaire per patient was completed by every implanting physician, in every center. The questionnaire was designed by the Section of Electrophysiology and Arrhythmias of the Spanish Society of Cardiology. The data from 306 automatic defibrillators implanted were reported. The percentage of defibrillators per inhabitant in Spain is close to 1 per 100,000. Eighty-five percent were first implants, while a 13% were replacements. Most of the electrodes used were endocardial. Chronic ischemic heart disease was found in 54% of the patients. Forty-six percent of the patients had syncopal ventricular tachycardia, 31% ventricular fibrillation and 23% sustained monomorphic ventricular tachycardia. The generator pocket was pectoral in 87% of the patients and abdominal in 13%. The implant of the defibrillator was associated with other cardiac surgery in only 3% of the patients.

Dosimetric and radiation protection considerations based on some cases of patient skin injuries in interventional cardiology

Recently, several cases of skin injuries have been detected in patients undergoing cardiac radiofrequency catheter ablation. These procedures were performed on a biplane X-ray system used in a large Spanish hospital for interventional cardiology procedures. Interventional procedures performed and radiation lesions produced on patients are described. The radiation lesions were mainly erythematous lesions and chronic radiodermatitis. Results of the dosimetric evaluations and an analysis of the operational aspects of radiological protection are discussed. Poor image quality could have influenced the length of the procedures. Dose rate at the image intensifier entrance was within usual reported values in literature. However, the focus-to-skin distance for the horizontal X-ray beam was too short, resulting in a high skin dose rate. Additionally, X-ray beams are of fixed orientation, and accumulated skin dose in the patient's right side has been estimated as 11-15 Gy per procedure. In conclusion, practical radiation protection considerations to avoid further incidents of this sort are proposed, concerning the use of X-ray systems specially designed for interventional radiology, the improvement of cardiologists' training in radiation protection and routine patient dose measurements for complex interventional procedures.

[Evaluation of biochemical markers of myocardial lesion after radiofrequency ablation. Value of troponin I]

INTRODUCTION AND OBJECTIVES

Radiofrequency catheter ablation is the curative treatment of choice for many cardiac arrhythmias. After radiofrequency ablation there is always a localized endomyocardial necrosis, which is necessary to eliminate the arrhythmia. The volume of the necrosis may be evaluated by the rise of several biochemical markers, classically CK and CK-MB. However, the sensitivity and specificity of these markers are not optimal and are probably less than ideal for this purpose. Cardiac Troponin I (cTnI) is a newly available biochemical marker available, with a high cardiac specificity. We designed this study in order to determine the value of serum levels of several cardiac markers in patients who underwent radiofrequency catheter ablation and to establish the utility of cTnI.

METHODS

We analyzed the data from 51 patients who underwent radiofrequency ablation and from 16 control patients. In respect to the ablation target, we included in the study 14 left accessory pathways, 7 right accessory pathways, 12 atrioventricular nodal reentry tachycardia, 5 ventricular tachycardia and 13 atrial flutter or fibrillation. The levels of CK, CK-MB, cTnI, and myoglobin were compared with clinical findings, ST-T wave abnormalities and the presence of arrhythmias after ablation. To evaluate the diagnostic capability for each biochemical marker we used the ROC curves.

RESULTS

A pathological value of cTnI was found in 47 out of 51 (92%) patients in the ablation group. CK-MB had a lower sensitivity (63%). The sensitivity for the other biochemical markers ranged from 30% for CK to 67% for Myoglobin. The area under the ROC curve for cTnI was 0.9375, significantly superior to the other biochemical markers (0.86, 0.76, 0.75 for MB, Myoglobin, CK respectively) (p < 0.05). The lowest cTnI released was found in patients after nodal reentry tachycardia ablation and the highest after atrial flutter ablation. cTnI increased above normal values in 4 patients in the control group (patients who underwent an electrophysiological study without catheter ablation). We found a moderate level of correlation between the number of radiofrequency pulses and cardiac cTnI release (r = 0.69; p < 0.0001). The correlation was different in each target, ranging between r = 0.25 (p = NS, 0.43) for atrial flutter and fibrillation to r = 0.99 (p < 0.0001) for ventricular tachycardia.

CONCLUSIONS

cTnI had the greatest sensitivity (92%) for detecting minor myocardial damage. Thus, we can conclude that the serum level of cTnI detects the minor myocardial damage produced by radiofrequency ablation.

[Human and technical resources of arrhythmia units in Spain in 1995]

The results of the Spanish registry for electrophysiology and arrhythmias activity are presented. A questionnaire was sent to all of the Arrhythmia Units in Spain, directed to their human and technical resources, and activity. The questionnaire was designed by the Section of electrophysiology and Arrhythmias of the Spanish. Society of Cardiology. The existence of an arrhythmia Unit, as an autonomous center, was recognized in 26 cases, at the end of 1995. In 13 centers there was no Arrhythmia Unit, but 11 wanted to develop one and in 2 it was not considered. Seven centers expected to create an Arrhythmia Unit during 1996. The first Arrhythmia Unit in spain was created in 1979. We have considered as a basic requirement the functional existence of a specific cardiac electrophysiological laboratory. Only 34 hospitals already have a Laboratory and 5 are waiting for the development of one. In 21 hospitals there are cardiologists particularly dedicated to electrophysiology, the number varies between 1 and 3 in each hospital. Radiofrequency catheter ablation is now considered the technique of choice for the treatment of most cardiac arrhythmias. This technique is currently being performed in Spain in 29 Hospitals and an additional 4 are expected to be able to perform it in the near future. Twenty-five hospitals implant automatic defibrillators, and the mean defibrillators implanted per hospital and year is 9.8 +/- 10.1.

[Intestinal perforation in Hirschsprung's disease. A clinical case in an adult and review of the literature]

Hirschsprung's disease is a fairly unusual case, even if not exceptional. For this reason we consider it interesting to present a iatrogenic perforation (of the patient) as a case of Hirschsprung's disease in adult age: the case was treated with urgency, at our surgical department.

Signal averaged electrocardiography in patients with acute myocarditis

This report describes the late potentials obtained by signal averaged electrocardiography (ECG) in 19 patients (13 male, 6 female, mean age 31 +/- 17 years) with acute myocarditis and their evolution. Five patients (26%) had positive signal averaged ECG in time domain analysis and two had technically inadequate signal averaged ECG. All five patients with positive signal averaged ECG, and 6 of the 12 patients with negative, developed heart failure (100%). One patient died. Signal averaged ECG was repeated at 3 months in all 18 surviving patients. Two patients had a good clinical evolution, normalized left ventricular function, and changed from positive to negative signal averaged ECG. All patients with heart failure on admission with negative signal averaged ECG had clinical improvement. Late potentials in patients with acute myocarditis are associated with a worse prognosis and greater extent of myocardial damage.

Heart rate variability and inappropriate sinus tachycardia after catheter ablation of supraventricular tachycardia

Sinus tachycardia has been reported after radiofrequency catheter ablation of supraventricular tachycardia. Frequently, these patients require beta-blocking agents for symptomatic control. The purpose of this study was to evaluate prospectively the incidence of inappropriate sinus tachycardia and heart rate variability after ablation of atrioventricular nodal reentrant tachycardia and accessory pathways. Patients undergoing ablation had 24-h ambulatory monitoring ECG (Holter) performed before the procedure, on the day of the ablation, and 3 months afterwards. There were 170 patients, mean age 48 +/- 23 years; 93 were female. A complete study of the 24-h Holter with analysis of heart rate variability: SD, rMSSD, pNN50, high and low frequency was obtained. There was a low prevalence of inappropriate sinus tachycardia after the ablation procedure (10 of 170 patients: five with four atrioventricular nodal reentry, with posteroseptal accessory pathways and one of the latter following ablation of the left accessory pathway). There was no modification of time and frequency domain parameters of heart rate variability in the remaining patients who underwent radiofrequency ablation. Holter monitoring 3 months after ablation showed that parameters of heart rate and heart rate variability had normalized in patients who had developed inappropriate sinus tachycardia. Inappropriate sinus tachycardia may be initiated by both radiofrequency ablation of atrioventricular nodal reentrant tachycardia and radiofrequency ablation of posteroseptal accessory pathways. Specific damage to the posteroseptal region is responsible for these changes, which usually recover spontaneously after 3 months.

[Usefulness of the RR variability in the diagnosis of neurogenic syncope]

INTRODUCTION AND PURPOSES: Autonomic nervous system plays an important role in the pathogenesis of vasovagal/vasodepressor syncope and may also be assessed by the RR variability analysis. Head up tilt test (HUT) is a currently established tool to evaluate patients with neuromediated syncope. However, the relationship between heart rate variability and tilt induced syncope is not established. The purpose of this study was to assess the differences in heart rate variability among patients with syncope and negative or positive tilt test.

METHODS

Fifty patients (mean age 33 +/- 17 years, 24 female, 26 male) with syncope underwent tilt test (20 min, 80 degrees tilt and 20 min more under isoproterenol infusion). Twenty-three patients have a negative tilt, the rest had a positive test. There were not significant differences in age or sex. Immediately after the HUT a 24-hour ambulatory electrocardiogram was performed (Marquette system 8000, 002A program). The parameters measured during Holter monitoring were: SDANN, SD, rMSSD, pNN50 and frequency analysis of heart rate spectrum (low frequency 0.04-0.15 Hz, high frequency 0.15-0.4 Hz and the relation low/high). No significant differences were detected in age and sex in patients with and without positive HUT.

RESULTS

pNN50 and rMSSD were the best predictors of the results of tilt (p = 0.006). SDANN and SDNN were not useful parameter. The finding of a value of pNN50 > 25% (value significantly different between patients with HUT--and +) have a specificity for predicting a positive HUT of 82.6%, with a sensibility of 51.8%. Positive predictive value was 77%. As can be easily understood, if the cut value of pNN50 is lowered, its sensibility increased and the specificity. decreased. In the frequency analysis only the relation low/high (L/H) was significantly different between both populations.

CONCLUSIONS

Heart rate variability is a useful tool in the evaluation of patients with vasovagal syncope, that may identify patients with chronically elevated vagal tone and thus may predict tilt test results.

[The efficacy and safety of intravenous propafenone in the acute treatment of spontaneous sustained ventricular tachycardia]

INTRODUCTION AND PURPOSES: Propafenone is an antiarrhythmic drug with well known electrophysiological effects. We performed this prospective non comparative study, in order to evaluate its efficacy and safety to terminate spontaneous episodes of monomorphic sustained ventricular tachycardia.

METHODS

Thirty-two episodes of sustained monomorphic ventricular tachycardia in 32 consecutive patients were treated with intravenous propafenone. Twenty-five were male and 7 female, mean age of 62 +/- 12 years; 23 suffered chronic ischemic heart disease, 2 dilated cardiomyopathy, 1 arrhythmogenic dysplasia of the right ventricle and 6 no organic heart disease. Patients with overt heart failure, acute myocardial infarction or a systolic blood pressure less than 90 mmHg were excluded. The ventricular origin of the tachycardia was assessed by clinical and electrocardiographic criteria and by the presence of AV dissociation in intraesophageal recording. The dose of propafenone was 0.2 mg/kg/min until interruption of ventricular tachycardia, or maximal dose of 2.5 mg/kg in 10 min.

RESULTS

In 23 episodes (72%) sinus rhythm was restored in less than 10 minutes (mean time and dose, 398 +/- 97 s and 95 +/- 42 mg, respectively). Two patients developed proarrhythmia with acceleration of the ventricular tachycardia. A significant decrease in blood pressure was noted in 6 patients. Presence of organic heart disease, advanced age and poor functional class were the best predictors of inefficacy to convert to sinus rhythm and of the presence of acute adverse effects (p < 0.05).

CONCLUSIONS

Propafenone is an effective drug for the acute conversion of spontaneous monomorphic sustained ventricular tachycardia, especially in patients without organic heart disease. Age, functional class and presence of organic heart disease could predict the response to propafenone and the incidence of complications.

Cardiovascular toxicities related to the infusion of cryopreserved grafts: results of a controlled study

To evaluate cardiovascular toxicities associated with the infusion of cryopreserved grafts, we prospectively monitored the infusions of 29 autologous bone marrow transplant (BMT) recipients. Fifteen allogeneic BMT recipients served as a control group. Cardiac rhythm was recorded continuously with the Holter technique from at least 2 h before the start of graft infusion until 24 h after completion. Blood pressure was closely monitored during the same period. Graft infusions were performed through a standard transfusion filter with breaks between aliquots. When the infusion had commenced, diuretics were given frequently (40 and 40% of allogeneic BMT and autologous BMT recipients, respectively) to avoid fluid overload. Non-cardiovascular clinical toxicities were observed more frequently in autologous BMT patients (41% vs 6%, p = 0.02) and no significant differences were seen between autograft and allograft recipients in any of the measured cardiovascular parameters. The heart rate decreased slightly in both groups but no patient in either group had a heart rate of < 60 b.p.m. or heart block. No significant changes in blood pressure were detected in either group. Ventricular ectopic beats/atrial ectopic beats ratio increased in the autologous BMT group after graft infusion (0.7 vs 0, p = 0.1). Time to engraftment did not differ significantly from other published series. Our results suggest that increasing infusion time of cryopreserved material and using a standard filter may reduce toxicities associated with the infusion of cryopreserved grafts. Early administration of diuretics may contribute to better control of blood pressure.

Comparison of flecainide and procainamide in cardioversion of atrial fibrillation

In this prospective, controlled and randomized cross-over study we tried to establish the efficiency and safety of flecainide vs procainamide for the treatment of acute atrial fibrillation. Eighty patients (30 females, 50 males, mean age: 55 +/- 14 years) were included. Patients entered into the study if they had atrial fibrillation of recent onset (< 24 h) with a ventricular rate > 100 beats.min-1 at rest and were < 75 years of age. Exclusion criteria were any sign of heart failure, conduction disturbances, sick sinus syndrome or acute ischaemic events. Randomly 40 patients received flecainide and 40 procainamide as the first treatment. There were no significant clinical difference between the two groups. Procainamide ws given at a dose of 1 g infused over 30 min, and followed by an infusion of 2 mg.min-1 over 1 h. Flecainide was given at a dose of 1.5 mg.kg-1 over 15 min followed by an infusion of 1.5 mg.kg-1 over 1 h. Drug infusion was continued until maximal dose, intolerance or reversion to sinus rhythm. After 1 h of wash out, patients remaining in atrial fibrillation were started on the second drug. Left atrial size was measured by echo. Serum levels of drug and atrial size did not differ between patients who returned to sinus rhythm and those who remained in atrial fibrillation. Conversion to sinus rhythm was achieved in 37 (92%) of the 40 patients treated with flecainide and 25 (65%) of those treated with procainamide (P < 0.001). The time required for reversion to sinus rhythm was similar between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

[The nonpharmacological treatment of tachyarrhythmias in 23 children and adolescents]

We comment the results with non pharmacological treatment in 23 patients (mean age 11 +/- 4 years) with multiple episodes of palpitations, most of them required intravenous drugs for interrupting it. Twenty-eight procedures were performed, 17 catheter ablation and 11 surgical interventions. The energy source employed for fulguration until 1990 was DC and since 1991 radiofrequency. The best results with catheter ablation were obtained with accessory pathways. Interruption was achieved in all patients after a mean of 1.2 sessions per patient, but it was definitive in only 72%. Most of the patients (81%) remained asymptomatic without antiarrhythmic drugs. Nine patients with accessory pathways underwent surgery interruption, it was achieved in all; only one patient had arrhythmia recurrence, due to a second pathway in a different localization. We could not ablate a ectopic atrial tachycardia, that underwent surgery. There was only one indication for surgery in a patient with ventricular tachycardia. Catheter ablation does not present technical problem in children and teenagers, different from adults. The presented results lead us to suppose that the indications for non pharmacological treatment in the young will become more common.

Atrial fibrillation in Wolff-Parkinson-White syndrome: reversal of isoproterenol effects by sotalol

Sotalol has Class II and III antiarrhythmic effects. Its efficacy and safety as a treatment of atrial fibrillation in patients with the Wolff-Parkinson-White (WPW) syndrome is controversial. We evaluated the effects of isoproterenol and IV sotalol (1.5 mg/kg in 10 minutes) given together versus isoproterenol alone on anterograde conduction through the AV node and accessory pathway. Atrial fibrillation was induced in 22 patients with WPW (13 men, 9 women, 36 +/- 16 years old). AV node and accessory pathway conduction were both enhanced by isoproterenol, although the effect was greater on the AV node. The minimum interval between preexcited QRS complexes shortened in all patients. Conversely, sotalol caused a significant prolongation of the shortest preexcited QRS interval as well as of the shortest interval between narrow QRS complexes. In addition, sotalol reversed all the effects of isoproterenol during atrial fibrillation. The percent of preexcited QRS complexes was not significantly modified because variations in ventricular preexcitation results from a balance between the relative effects on refractoriness of the accessory pathway versus of the AV node and in the amount of respective anterograde and retrograde concealed conduction. There were no serious adverse effects. Reversion to sinus rhythm was documented in 12 patients (60%). These short-term observations suggest that sotalol may be safe and effective in the treatment of patients with WPW and atrial fibrillation.