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Background: Ventricular and supraventricular premature complexes (PC) are frequent and usually symptomatic. According to a previous study, magnesium pidolate (MgP) administration to symptomatic patients can improve the PC density and symptoms., Objective: To assess the late follow-up of that clinical intervention in patients treated with MgP or placebo., Methods: In the first phase of the study, 90 symptomatic and consecutive patients with PC were randomized (double-blind) to receive either MgP or placebo for 30 days. Monthly follow-up visits were conducted for 15 months to assess symptoms and control electrolytes. 24-hour Holter was performed twice, regardless of symptoms, or whenever symptoms were present. In the second phase of the study, relapsing patients, who had received MgP or placebo (crossing-over) in the first phase, were treated with MgP according to the same protocol., Results: Of the 45 patients initially treated with MgP, 17 (37.8%) relapsed during the 15-month follow-up, and the relapse time varied. Relapsing patients treated again had a statistically significant reduction in the PC density of 138.25/hour (p < 0.001). The crossing-over patients reduced it by 247/hour (p < 0.001). Patients who did not relapse, had a low PC frequency (3 PC/hour). Retreated patients had a 76.5% improvement in symptom, and crossing-over patients, 71.4%., Conclusion: Some patients on MgP had relapse of symptoms and PC, indicating that MgP is neither a definitive nor a curative treatment for late follow-up. However, improvement in the PC frequency and symptoms was observed in the second phase of treatment, similar to the response in the first phase of treatment.

Background: Sudden death is the leading cause of death in Chagas disease (CD), even in patients with preserved ejection fraction (EF), suggesting that destabilizing factors of the arrhythmogenic substrate (autonomic modulation) contribute to its occurrence., Objective: To determine baroreflex sensitivity (BRS) in patients with undetermined CD (GI), arrhythmogenic CD with nonsustained ventricular tachycardia (NSVT) (GII) and CD with spontaneous sustained ventricular tachycardia (STV) (GIII), to evaluate its association with the occurrence and complexity of arrhythmias., Method: Forty-two patients with CD underwent ECG and continuous and noninvasive BP monitoring (TASK force monitor). The following were determined: BRS (phenylephrine method); heart rate variability (HRV) on 24-h Holter; and EF (echocardiogram)., Results: GIII had lower BRS (6.09 ms/mm Hg) as compared to GII (11.84) and GI (15.23). The difference was significant between GI and GIII (p = 0.01). Correlating BRS with the density of ventricular extrasystoles (VE), low VE density (<10/h) was associated with preserved BRS. Only 59% of the patients with high VE density (> 10/h) had preserved BRS (p = 0.003). Patients with depressed BRS had higher VE density (p = 0.01), regardless of the EF. The BRS was the only variable related to the occurrence of SVT (p = 0.028)., Conclusion: The BRS is preserved in undetermined CD. The BRS impairment increases as disease progresses, being more severe in patients with more complex ventricular arrhythmias. The degree of autonomic dysfunction did not correlate with EF, but with the density and complexity of ventricular arrhythmias.

Background: Several mechanisms may be involved in the trigger of syncope in patients with hypertrophic cardiomyopathy (HCM), including hemodynamic collapses that might be related to an autonomic imbalance., Objective: To evaluate and compare the autonomic function of patients presenting HCM with unexplained syncope (US) to those without syncope., Methods: Thirty-seven patients were included, 16 with US and 21 without syncope. Their autonomic function was assessed by spontaneous and phenylephrine induced baroreflex sensitivity (BRS), by heart rate variability (HRV) in time domain during 24-hour Holter and in frequency domain (spectral analysis), both in supine position and at 70º head-up tilt (HUT)., Results: The spontaneous BRS was similar in both groups (16,46 ± 12,99 vs. 18,31 ± 9,88 ms/mmHg, p = 0,464), as was phenylephrine-induced BRS (18,33 ± 9,31 vs. 15,83 ± 15,48 ms/mmHg, p = 0,521). No differences were observed in SDNN (137,69 ± 36,62 vs . 145,95 ± 38,07 ms, p=0,389). The group presenting syncope had a significantly lower RMSSD (24,88±10,03 vs. 35,58 ± 16,43 ms, p = 0,042) and a tendency to lower pNN50 (4,51 ± 3,78 vs . 8,83 ± 7,98%, p =0,085) and lower values of the high frequency component of HRV spectral analysis at rest (637,59±1.295,53 vs. 782,65±1.264,14ms2, p=0,075). No significant difference was observed in response to HUT (p = 0,053). HUT sensitivity, specificity and accuracy in identifying the etiology of US in HCM patients were 6%, 66% and 40%, respectively., Conclusions: A lower parasympathetic tone was observed in HCM patients with US, but the clinical relevance of this finding remains unclear. HUT is not a valuable tool for evaluating the origin of syncope in these patients, mainly because of its poor specificity.

Background: Premature ventricular and supraventricular complexes (PVC and PsVC) are frequent and often symptomatic. The magnesium (Mg) ion plays a role in the physiology of cell membranes and cardiac rhythm., Objective: We evaluated whether the administration of Mg Pidolate (MgP) in patients with PVC and PsVC is superior to placebo (P) in improving symptoms and arrhythmia frequency., Methods: Randomized double-blind study with 60 consecutive symptomatic patients with more than 240 PVC or PsVC on 24-hour Holter monitoring who were selected to receive placebo (P) or MgP. To evaluate symptom improvement, a categorical and a specific questionnaire for symptoms related to PVC and PsVC was made. Improvement in premature complex density (PCD) per hour was considered significant if percentage reduction was >70% after treatment. The dose of MgP was 3.0 g/day for 30 days, equivalent to 260 mg of Mg element. Any patient had structural heart disease or renal failure., Results: Of the 60 patients, 33 were female (55%). Ages ranged from 16 to 70 years old. In the MgP group, 76.6% of patients had a PCD reduction >70%, 10% of them >50% and only 13.4% <50%. In the P group, 40% showed slight improvement, <30%, in the PC frequency (p < 0.001). Symptom improvement was achieved in 93.3% of patients in the MgP group, compared with only 16.7% in the P group (p < 0.001)., Conclusion: Oral Mg supplementation decreases PCD, resulting in symptom improvement.

Background: The occurrence of atrial fibrillation (AF) after successful ablation of cavotricuspid isthmus-dependent atrial flutter (CTI-AFL) is an important medical event, but predictors of this event are still controversial., Objective: To determine the incidence of AF and its predictors in patients undergoing ablation of cavotricuspid isthmus-dependent atrial flutter (CTI-AFL)., Methods: Fifty two patients with CTI-AFL underwent ablation from January 2003 to March 2004, in Instituto do Coração (InCor), Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo., Results: During the mean follow-up period of 26.2 +/- 9.2 months, 16 (30.8%) patients presented AF. The univariate analysis revealed two clinical variables as predictive of the occurrence of AF after ablation of CTI-AFL for three years or longer (RR: 3.00; p = 0.020). In the multivariate analysis, these factors were independent variables associated with the occurrence of AF after ablation of CTI-AFL., Conclusion: AF is frequently observed during the follow-up of patients undergoing ablation of CTI-AFL. Persistent CTI-AFL and history of arrhythmia for more than three years are predictors of the occurrence of AF during the clinical follow-up.

Background: Most of the studies on this subject have reported predictors of recurrence of atrial fibrillation after catheter ablation with relatively short follow-up periods., Objective: To retrospectively evaluate predictors of long-term recurrence of paroxysmal atrial fibrillation (AF) in patients undergoing pulmonary vein isolation following one single procedure., Methods: The authors studied a total of 139 patients (102 men; mean age of 55 +/- 12 years) undergoing radiofrequency ablation using the ostial or extra-ostial techniques for left atrial approach, combined or not with cavotricuspid isthmus ablation (CTI). Pre, intra and post-ablation variables were evaluated using univariate and multivariate analyses to determine the predictors of recurrence of AF after one procedure., Results: After a 33 +/- 12-month follow-up, we observed that a longer time of history of AF, use of more antiarrhythmic drugs, and recurrence of AF within 60 days post-procedure increased the risk of long-term recurrence of AF. On the other hand, the association of atrial flutter and concomitant CTI ablation reduced the risk of recurrence of AF., Conclusion: Clinical variables such as time of history of AF and a larger number of antiarrhythmic drugs already used influenced the outcomes of catheter ablation. In patients with associated atrial flutter, simultaneous CTI block significantly reduced the long-term recurrence of atrial fibrillation.

Objective: To evaluate the outcome of patients with NCS after interruption of pharmacological therapy and to investigate the possible clinical variables predicting recurrence., Methods: Thirty-seven patients (age 31+/-16 years) with refractory recurrent NCS being 19 females where prospectively studied. All patients became asymptomatic and had a negative tilt table test (TT) after pharmacological therapy. The treatment was interrupted and one month later, a new TT with no medication was carried out. The probability free of symptoms recurrence was analyzed according to sex, age, number of syncope episodes previously to the treatment, clinical history time, treatment time, drug free from treatment time and TT result., Results: Twenty-two patients (59%) presented recurrence during a mean follow-up of 21+/-19.7 months. The variables related to greater recurrence were number of previous syncope (p=0.0248), positive TT after interruption of the therapy (p=0.0002) and female gender (p=0.0131)., Conclusions: Most of the very symptomatic patients with NCS present recurrence after the suppression of a specific therapy. A TT carried out after treatment discontinuation can identify patients with higher risk of recurrence, specially in the first year of follow-up.

Objective: The purpose of this study was to access the clinical outcome of patients submitted to a single procedure of radiofrequency pulmonary veins (PV) isolation to treat refractory paroxysmal atrial fibrillation (AF)., Methods: This study included 49 consecutive patients (36 male; mean age 54+/-10 years old) who had frequent symptomatic paroxysmal AF refractory to at least three antiarrhythmic drugs. We used a circular decapolar catheter for mapping PVs - left atrial connections and a 4-mm distal tip catheter for ablation (30 W and 50 C), aiming to achieve electrical isolation of 3 -4 PVs., Results: Twenty-five patients (51%) did not present any AF recurrence in a mean follow-up of 12+/-5 months. Twenty-four (49%) had at least one recurrence during outcome; twenty (83%) of them within the first month after the procedure and four after two to nine months. After introducing antiarrhythmic drugs 15 (63%) patients were under control, 10 were asymptomatic and five complained of sporadic short duration AF episodes. Nine (37%) patients remained very symptomatic despite the use of antiarrhythmic drugs and were referred to a new procedure of PV isolation. No patient presented major complications. At the end of the follow-up, 35 (71%) patients remained in stable sinus rhythm with no AF recurrences after a single procedure, 50% of them without antiarrhythmic drugs., Conclusion: Most patients who present symptomatic paroxysmal AF refractory to antiarrhythmic drugs obtain a good clinical control after a single PV isolation procedure.

Objective: To evaluate the influences of circadian variations on tilt-table testing (TTT) results by comparing the positivity rate of the test performed during the morning with that of the test performed in the afternoon and to evaluate the reproducibility of the results in different periods of the day., Methods: One hundred twenty-three patients with recurrent unexplained syncope or near-syncope referred for TTT were randomized into 2 groups. In group I, 68 patients, TTT was performed first in the afternoon and then in the morning. In group II, 55 patients, the test was performed first in the morning and then in the afternoon., Results: The TTT protocol was the prolonged passive test, without drug sensitization. Twenty-nine (23.5%) patients had a positive result in at least one of the periods. The positivity rate for each period was similar: 20 (16.2%) patients in the afternoon and 19 (15.4%) in the morning (p=1.000). Total reproducibility (positive/positive and negative/negative) was observed in 49 (89%) patients in group I and in 55 (81%) in group II. Reproducibility of the results was obtained in 94 (90.4%) patients with first negative tests but in 10 (34%) patients with first positive tests., Conclusion: TTT could be performed during any period of the day, and even in the 2 periods to enhance positivity. Considering the low reproducibility rate of the positive tests, serial TTT to evaluate therapeutic efficacy should be performed during the same period of the day.

Purpose: Upright tilt-table testing (UTT) is an useful method for identifying patients with neurocardiogenic syncope, but its role in the evaluation of therapeutic efficacy is controversial. The aim of this study was to determine the correlation between negative UTT after therapy introduction (acute efficacy) and symptom recurrence during follow-up (chronic efficacy)., Methods: We studied 56 severely symptomatic patients (age 27 +/- 19 years) with recurrent (7 +/-12 episodes) neurocardiogenic syncope (positive UTT). Once empirical pharmacological therapy was initiated, all patients underwent another UTT (therapeutic evaluation test - TET). Therapy was not modified after TET results. The probability of symptom recurrence was analyzed with the Kaplan-Meier method and compared by log-rank test in patients with negative and positive TET., Results: Negative UTT after therapy was related to a significantly lower probability of recurrence during follow-up (4.9 versus 52.4% in 12 months, P<0.0001)., Conclusion: A good correlation exists between acute and long-term efficacy of pharmacological therapy for neurocardiogenic syncope, so that serial UTT may be considered a good method for identifying an effective therapeutic strategy.

Purpose: To analyze the influence of biventricular pacing (BP) on clinical behavior, ventricular arrhythmia (VA) prevalence, and left ventricular ejection fraction (LV EF) by gated ventriculography., Methods: Twenty-four patients with left bundle branch block (LBBB) and NYHA class III and IV underwent pacemaker implantation and were randomized either to the conventional or BP group, all receiving BP after 6 months., Results: Sixteen patients were in NYHA class IV (66.6%) and 8 were in class III (33.4%). After 1-year follow-up, 14 patients were in class II (70%) and 5 were in class III (25%). Two sudden cardiac deaths occurred. A significant reduction in QRS length was found with BP (p=0.006). A significant statistical increase, from a mean of 19.13 +/- 5.19% (at baseline) to 25.33 +/- 5.90% (with BP) was observed in LVEF Premature ventricular contraction prevalence decreased from a mean of 10,670.00 +/- 12,595.39 SD or to a mean of 3,007.00 +/- 3,216.63 SD PVC/24 h with BP (p<0.05). Regarding the hospital admission rate over 1 year, we observed a significant reduction from 60. To 16 admissions with BP (p<0.05)., Conclusion: Patients with LBBB and severe heart failure experienced, with BP, a significant NYHA class and LVEF improvement. A reduction in the hospital admission rate and VA prevalence also occurred.

OBJECTIVE - To assess the diagnostic value, the characteristics, and feasibility of tilt-table testing in children and adolescents. METHODS - From August 1991 to June 1997, we retrospectively assessed 94 patients under the age of 18 years who had a history of recurring syncope and presyncope of unknown origin and who were referred for tilt-table testing. These patients were divided into 2 groups: group I (children) - 36 patients with ages ranging from 3 to 12 (mean of 9.19+/-2.31) years; group II (adolescents) - 58 patients with ages ranging from 13 to 18 (mean of 16.05+/-1.40) years. We compared the positivity rate, the type of hemodynamic response, and the time period required for the test to become positive in the 2 groups. RESULTS - The positivity rates were 41.6 % and 50% for groups I and II, respectively. The pattern of positive hemodynamic response that predominated in both groups was the mixed response. The mean time period required for the test to become positive was shorter in group I (11.0+/-7.23 min) than in group II (18.44+/-7.83 min). No patient experienced technical difficulty or complications. CONCLUSION - No difference was observed in regard to feasibility, positivity rate, and pattern of positive response for the tilt-table test in children and adolescents. Pediatric patients had earlier positive responses.

Objective: To assess the incidence of problems requiring reprogramming of atrioventricular pacemakers in a long-term follow-up, and also the causes for this procedure., Methods: During the period from May '98 to December '99, 657 patients were retrospectively studied, An actuarial curve for the event reprogramming of the stimulation mode was drawn., Results: The follow-up period ranged from 12 to 178 months (mean = 81 months). Eighty-two (12.4%) patients underwent reprogramming of the stimulation mode as follows: 63 (9.5%) changed to VVI,(R/C); 10 (1.5%) changed to DVI,C; 6 (0.9%) changed to VDD,C; and 3 (0.5%) changed to DOO. The causes for the reprogramming were as follows: arrhythmia conducted by the pacemaker in 39 (37.6%) patients; loss of atrial sensitivity or capture, or both, in 39 (38.6%) patients; and microfracture of atrial electrode in 5 (4.9%) patients. The stimulation mode reprogramming free probability after 15 years was 58%., Conclusion: In a long-term follow-up, the atrioventricular pacemaker provided a low incidence of complications, a high probability of permanence in the DDD,C mode, and the most common cause of reprogramming was arrhythmia conducted by the pacemaker.

Ebstein's anomaly with coarctation of the aorta is an extremely unusual condition. In this report, the clinical and surgical features of 3 male patients, aged 7 months, 4 years and 14 years, are discussed. All patients were in situs solitus. The first 2 patients had atrioventricular and ventriculoarterial discordance and progressed to heart failure in the neonatal period. The third had atrioventricular and ventriculoarterial concordance, as well as Wolf-Parkinson-White syndrome, with frequent episodes of paroxysmal tachycardia. The 3 patients underwent surgery for correction of the coarctation of the aorta. The patient with atrioventricular and ventriculoarterial concordance underwent tricuspid valvuloplasty using a DeVega-like technique. In addition, ablation of 2 anomalous pathways (Kent bundle), which were detected by the electrophysiologic study, was also subsequently performed. The 3 patients showed a good postoperative outcome for 2 years, although, in those with discordance, the surgical procedure did not influence the dysplasia of the tricuspid valve, because this valve showed light to moderate dysfunction.

Purpose: To determine the clinical importance of a bi-directional line of block demonstration in the inferior vena cava-tricuspid annulus isthmus as an end-point for radiofrequency (RF) atrial flutter (FL) ablation., Methods: Forty consecutive patients (51 +/- 11 years) with type I FL were divided in 2 groups: GI (30 patients) anatomic, non-electrophysiologic isthmus ablation technique (interruption and non-induction FL criteria); and GII (10 patients) anatomic with electrophysiologic evaluation of bi-directional isthmus conduction. The isthmus activation was analyzed before and after anatomic RF ablation with a cateter exploring each side of the line of block, depending on the conduction evaluation (anterograde or retrograde)., Results: FL was interrupted and not reinduced in 26/ 30 (86.6%) GI patients and in 10 (100%) GII patients (p = 0.5558). During follow-up FL recurred in 30% of the patients in both groups. In GII, 6 patients with bi-directional block remained assymptomatic, whereas 3 patients with unidirectional block presented recurrence (p = 0.012)., Conclusion: Electrophysiologic demonstration of bidirectional line of block in the isthmus is related to long-term success and should be the criterion for interruption of type I atrial FL RF ablation.

Purpose: The aim of this study is to verify whether the persistence of conduction over the slow pathway is related to an increased trend for recurrence., Methods: Recurrence rate was retrospectively analyzed in 126 patients who underwent slow pathway radiofrequency (RF) catheter ablation during a follow-up of 20 +/- 12 months. The ablative procedure was interrupted when AVNRT was no longer induced by atrial stimulation after intravenous infusion of isoproterenol. Ninety-eight patients had no evidence of slow pathway whereas 28 patients persisted with AV node jump and atrial echo beat., Results: There were 15 recurrences: 9% of those who had no evidence of slow pathway (9 of 98 patients) and 21% of those with AV node jump and/or atrial echo beat but this difference was not statistically significant., Conclusion: As long as AVNRT cannot be induced by atrial pacing and isoproterenol infusion after slow pathway RF catheter ablation, the presence of AV node jump and/or atrial echo beat does not increase the risk of recurrence of AVNRT.

Purpose: The aim of this study was to determine prevalence and the underlying mechanism of persistent palpitations after successful radiofrequency ablation of reentrant nodal tachycardia and atrioventricular tachycardia., Methods: One hundred twenty consecutive patients (mean age of 36 +/- 16 years) who underwent radiofrequency catheter ablation of atrioventricular or reentrant nodal tachycardia constituted the analyzed group. Prevalence of palpitations was investigated during out-clinic visits and telephone interviews. Patients complaining of palpitations were divided in 2 groups: 1) those in whom palpitations lasted more than 30 seconds, and 2) those in whom the paroxysms lasted < 30 seconds (group II). All patients underwent clinical evaluation, ECG and Holter monitoring. Transesophageal atrial pacing and electrophysiologic stimulation were carried out when judged necessary., Results: During a follow up period of 9 +/- 4 months, 52 patients complained of palpitations. In 31 group I patients, palpitations were related to ventricular and atrial premature beats as shown during Holter monitoring. In group II patients, eight had recurrence, five presented a new arrhythmia not recognized previously to the ablative procedure and two patients had their symptoms related to arrhythmias recognized before ablation but taken as asymptomatic. The mechanism of palpitations was not identified in six patients., Conclusion: Palpitations may persist in 43% of patients who undergo radiofrequency ablation to treat reentrant nodal tachycardia and atrioventricular tachycardia. Recurrence and treatment are more likely when palpitations last longer than 30 seconds.

Purpose: To evaluate the efficacy and safety of intravenous (IV) adenosine-triphosphate (ATP) and verapamil to convert acute episodes of paroxysmal supraventricular tachycardia (PSVT) to sinus rhythm., Methods: Fifty patients with PSVT were randomized in two groups: A) 25 treated with IV bolus of ATP (10 or 20mg), and V) 25 treated with IV verapamil, up to 15mg, during 3min. We evaluated the time delay necessary to convert the arrhytmia, doses, and side-effects. Patients with acute ischemic syndromes (< 3 weeks), severe congestive heart failure, and treatment with dipyridamole or methylxanthine were excluded., Results: There were no differences between the two groups regarding to age, sex, and success rate. The average time till reversal were respectively, 30s and 248s for ATP and verapamil. Ventricular ectopy and general discomfort were observed in 33% of patients receiving ATP, whereas no side-effects occurred in group V., Conclusion: ATP is a good option to convert rapidly PSVT to sinus rhythm and, probably, could be the first choice to treat PSVT patients with ventricular dysfunction.

Purpose: To evaluate differences between amiodarone, procainamide and quinidine in the time delay necessary to convert acute atrial fibrillation (AF) to sinus rhythm., Methods: Sixty patients with acute AF were randomized in three groups (G) and treated with: quinidine (QG)-(21 patients) i.v. digital + quinidine up to 600 mg; procainamide (PG)-(23 patients) i.v. digital + i.v. procainamide, 10 mg/kg; amiodarone (AG)-(16 patients) i.v. amiodarone, 5 mg/kg. To evaluate time delay to conversion, all patients have their rhythm recorded by Holter system during four hours. Statistics were done with x2, considering significant a p < 0.05., Results: There were no differences between groups regarding to age, gender and delay from symptoms initiation and medical assistance. Conversion to sinus rhythm occurred, in QG-71.4% cases; PG-47.8% and AG-50% (p > 0.05). Time delay in minutes to conversion were, respectively (media +/- SD): QG-112 +/- 43; PG-44.1 +/- 28; AG-20 +/- 13, significantly lower in PG and AG related to QG (p = 0.001). Although not significant, side effects were observed mostly in PG., Conclusion: Amiodarone is a good choice to convert, very quickly, acute AF. Otherwise, quinidine has the best rate of conversion but with a longer time delay.

Purpose: To verify the efficacy and safety of the creation of a barrier with radiofrequency (RF) in the tricuspid annulus and the vena cava ostium (TA-IVC)., Methods: Nine consecutive patients, 7 males, with age ranging from 36 to 76 years, with paroxysmal (7 patients) or permanent (2) type I atrial flutter (negative P wave in lead II, III and F) were submitted to RF ablation of TA-IVC istmo. One deflectable catheter with 4mm size tip was introduced into the right ventricle apex and pulled back to the inferior vena cava. When the atrial electrogram was detected the RF application was started. The RF was applied (20 watts during 60s) up to the proximity of inferior vena cava ostium. The end point was to stop atrial flutter. Then a vigorous atrial stimulation protocol, including isoproterenol infusion was used. In the next day, patients were submitted to transesophageal stimulation with the same protocol., Results: Atrial flutter was interrupted in all patients (100%) with 4 to 28 (mean 16.7 +/- 7.7) applications. Eight patients (88.8%) with one session and 1 (11.1%) with two sessions. The mean time spent to stop the atrial flutter with one application was 30.5 +/- 18.5s. There were no complications. After a mean follow up of 3 +/- 1.6 month all patients (100%) are asymptomatic. Two of them are taking propranolol to control symptomatic atrial and ventricular ectopic beats., Conclusion: RF ablation of the TA-IVC istmo is efficient and safe in a short term follow up to interrupt and prevent re-induction and recurrence of type I atrial flutter.

Purpose: To correlate the incidence of arrhythmias to the degree of allograft rejection on endomyocardial biopsy., Methods: Seventeen patients who underwent orthotopic heart transplantation were submitted to ambulatory Holter monitoring 24h prior to endomyocardial biopsy. The biopsy results were compared to Holter monitoring results., Results: The mean study period was 252 +/- 166 days (15 to 515). We found a high incidence of ventricular premature beats (> 70%), except in patients with severe rejection (25%), but there was no statistically significant difference between the groups with no rejection, mild and moderate rejection. Atrial premature beats were more common in patients with mild and moderate rejection (53% and 70%, respectively) when compared to patients with no rejection (33%) and patients with severe rejection (9%), (p < 0.05). Sinus bradycardia was present in 50% of patients with severe rejection, but only in 9% of moderate, 3% of mild and 5% of the patients with no rejection (p < 0.05)., Conclusion: Supraventricular tachycardia and atrial premature beats are related to moderate rejection. Ventricular premature beats are not related to degree of rejection. Sinus bradycardia occurring in the first year after transplantation should suggest severe cardiac allograft rejection.

Purpose: In order to identify the reproducibility of head-up tilt test, a second test one week later in 22 patients with a positive first test, was performed., Methods: The test was performed in a fasting state during the morning. The heart rate and blood pressure were monitored during 20 minutes in the supine position and then at 60 degrees for up to 40 minutes. The test were considered positive if the patient experienced syncope or pre-syncope with fall in systolic blood pressure > 30mmHg. The following aspects were evaluated: reproducibility of the positive response; the type of response (hypotension, asystole or hypotension plus bradycardia) and the time interval between tilt and the beginning of symptoms., Results: Eighteen (82%) patients had a second positive response; 14 (77.8%) of then had the same type of response; and 17 (94%) had syncope in similar time interval after tilt., Conclusion: The head-up tilt testing has good reproducibility, although its use in the therapeutic management needs a longer period of evaluation.

Purpose: In order to identify neurally mediated syncope, head-up tilt testing was performed in patients with recurrent unexplained syncope., Methods: The tests were performed in 125 patients in the fasting state, between 8:30 and 11:30 a.m. The blood pressure and heart rate were continuously monitored during 20 minutes in the resting state, and then, positioned at 60 degrees angle, for up to 40 minutes. A group of 20 patients with first negative test was submitted to intravenous isoproterenol in bolus of 2 micrograms every 2 minutes until symptoms occur or at a total dose of 8 micrograms. The test was considered positive when systolic blood pressure decreased at least 30 mmHg and the patient experimented syncope or pre-syncope., Results: In 52 patients the test was positive (41.6%), 63.5% of which had hypotension exclusively; 7.7% asystole; and 28.8% had hypotension and bradycardia. Nine of the 20 patients submitted to isoproterenol test were positive (45%). All patients recovered spontaneously after returning to supine position., Conclusion: Head-up tilt testing is a safe and effective method for the identification of neurally mediated syncope.

Purpose: To evaluate the results of direct current catheter ablation of accessory pathways by mean of a new low energy power source., Methods: Catheter ablation was performed in 40 consecutive patients (23 male, mean age 31 +/- 11 years) with accessory atrioventricular pathways (AP) using a low energy DC power source. The electrophysiologic study and AP ablation were performed in the same procedure by endocardial approach using non-deflectable 6F bi, tri, or quadripolar electrodes., Results: AP was located at left free wall (LFW) in 22 patients (55%), posteroseptal (PS) in 11 patients (27.5%), anteroseptal (AS) in 5 patients (12.5%) and right lateral (RL) in 2 patients (5.0%). A mean of 7.7 +/- 7 catodal shocks of 5-75 (20) joules (J) was delivered in 1.45 +/- 7 sessions, with a mean cumulative energy of 178 +/- 213J per patient. The mean values of number of shocks, number of sessions and cumulative energy per patient were lower in LFW AP ablation than in other positions (5 +/- 4 x 11 +/- 8 - p = 0.008; 1.1 +/- 0.3 x 1.8 +/- 0.9 - p = 0.008 and 118 +/- 150 x 260 +/- 245 - p = 0.03). The mean CK-MB rise was 18.5 +/- 7.8U/1. Three patients (7.5%) presented hemopericardium after PS AP ablation and in 1 patient (2.5%), a PS AP (paranodal pathway) ablation resulted in total atrioventricular block. During a follow-up of 9.5 +/- 4 months AP was absent in 28 (70%) patients; 18/22 (82%) with LFW AP, 6/11 (54%) with PS AP, 3/5 (60%) with AS AP and 1/2 (50%) with RL-AP, (p = 0.10)., Conclusion: Low energy DC ablation is effective for AP ablation. The results are related with AP position.

Purpose: To analyze the long-term results of surgical treatment of atrioventricular nodal reentrant tachycardia (AVNT)., Methods: From March 1987 to March 1990, 20 patients with AVNT were submitted to surgical therapy, 14 female, aged 12 to 70 (42.8 +/- 17) years. All presented crisis of AVNT from 6 months to 60 (18.4 +/- 15.9) years. Ten of them had syncope or near syncope and two with cardiac arrest during reversion of AVNT with antiarrhythmic drugs. They used 1 to 6 (3.75 +/- 1.45) antiarrhythmic drugs before surgery. The electrophysiologic study (EPS) showed the common form of AVNT in all cases. The surgical procedure was anatomically directed to the posterior area of the AV node. Programmed atrial stimulation (PAS) were applied on 18 patients after surgery. The long-term results were analysed by clinical evaluation, EPS and Holter when they were necessary., Results: The postoperative PAS was done in 18 patients and did not induce any AVNT, even after atropine IV. The PR interval was 153 +/- 50 ms before and 152 +/- 38 ms after surgery (p > 0.05). During follow up (26 +/- 10 m) there were not AVNT recurrence. Two patients developed chronic atrial fibrillation after 24 months of surgery., Conclusion: The perinodal dissection technique used was safe and successful to treat AVNT, preserving AV nodal conduction.

Purpose: To study the spontaneous variability of single (VPCs) and coupled (CVPCs) in patients with chronic Chagas' disease (CCD)., Patients and Methods: Twenty patients with CCD, 14 male, in class I and II NYHA, with frequent VPCs and VCPCs, free of drug therapy were studied. 21 hour Holter monitoring was done for 4 subsequent days. The data analysis assessed the variation in the frequency of VPCs and CVPCs between patients, seven hour periods one hour periods in a hierarchical model by a Poisson process., Results: a) the frequency of VPCs follows a circadian rhythm, closely related to the hourly variations of the mean heart rate; b) disregarding the heart rate influence on the variability of the ventricular arrhythmia, its behavior was at random and unpredictable; c) the minimal percentual reduction in VPCs/h that discriminated between antiarrhythmic effect and spontaneous between antiarrhythmic effect and spontaneous between antiarrhythmic effect and spontaneous variability was 121.86% for seven-hour, 58.42% for 21-hour and 38.45% for 42-hour electrocardiographic monitoring periods; d) the same approach for the VCPCs revealed values of 133.6%, 63.21% and 41.3% respectively., Conclusion: The large variability of ventricular arrhythmia in CCD during a 24 hour period makes necessary observations always longer. The minimal percentual reduction in VPCs/h that discriminated between antiarrhythmic effect and spontaneous variability might be 58.42% for two 21-hour electrocardiography monitoring periods.

Purpose: To evaluate the behavior of single chamber stimulation system, rate responsive with vibration sensing, taking into consideration the results of long term clinical follow-up., Patients and Methods: From september 1986 to april 1989, 70 patients received pacemakers with vibration sensing. Sixty four patients (91.9%) implanted Activitrax I model and six (8.1%) Activitrax II. Thirty-one (44.3%) were men and the mean age was 51.2 years. Fifty-one patients (72.9%) had complete atrioventricular block, 11 (15.7%) sinus node dysfunction, one (1.4%) sinus node and atrioventricular disease, and one (1.4%) for therapeutic support of arrhythmia. The etiology of these dysfunctions were Chagas' disease in 31.4%, myocardiosclerosis in 35.7%, post-operative in 15.6%, post-av node fulguration in 5.8% and idiopathic in 11.5%. The group was submitted to clinic and electronic evaluation and laboratory examinations: echocardiogram, dynamic ECG, stress test and ergoespirometric test. The mean follow-up as 19.6 months., Results: Clinic evaluations: decrease in congestive heart failure functional class in 86% of the patients. No recurrence of syncopes and no cardiac deaths. Echocardiogram: increase in ejection fraction in 42% of patients. Dynamic ECG: appropriate rate response in 94.3% of patients (good cronotropic response). Ergoespirometry: increase in oxygen consumption in 75% of studied cases, Electronic evaluation: absence of generator dysfunction; complications in 18% of cases, all corrected by reprogramation., Conclusion: The single chamber cardiac stimulation system with vibration sensing showed safety, efficacy and low rate of complications.

Purpose: To evaluate the efficacy and safety of long-term empiric amiodarone therapy in patients with recurrent Sustained Ventricular Tachycardia (SVT) and Chronic Chagasic Myocarditis (CCM)., Patients and Methods: Thirty-five patients with CCM and SVT, eighteen (51%) of them were refractory to other antiarrhythmic drugs. The Amiodarone loading dose was between 600 and 1200 mg/day, mean of 883 +/- 239 mg/day, from a period of one to four weeks. The maintenance dose was decreasing in the follow-up period, it fell down to 356 +/- 125 mg/day at the end of six to 80 (mean = 27 +/- 20) months. Cumulative, event-free interval curves were generated by the Kaplan-Meier method. Clinical variables were compared with the use of the Student t-test or by means of chi-square tests., Results: The probability to suppress SVT was, 0.62 in 12 months, 0.56 in 24 months and 0.44 in 36 months, with regular use of amiodarone. The probability to the occurrence of sudden death was 0.0 in 12 months, 0.04 in 24 months and 0.11 in 36 months. The stratification of risk to clinical recurrence was significative to the left ventricular disfunction. All patients with functional class III or IV and LV ejection fraction less than 30% at radioisotopic ventriculography had clinical recurrence, while just 30% of patients with functional class I and II have got it (p less than 0.05). Fifteen (42.8%) patients had side effects. The treatment was discontinued in four patients (11.5%)., Conclusion: The empiric treatment with amiodarone apparently was effective in patients with SVT and CCM and functional class I and II. Patients with functional class III and IV did not get benefits from the treatment. In these cases other therapy must be pointed out.

Purpose: To find out whether is there a relation between electrophysiology laboratory ventricular arrhythmias through programmed ventricular stimulation, and the occurrence of relevant clinical events, particularly, sudden death, in patients victims of first episode of myocardial infarction., Patients and Methods: Twenty-seven patients (all males) who suffered non-complicated first myocardial infarction, with age varying from 47 to 70 (mean 54 +/- 6) years were prospectively and consecutively studied. Upon consent, patients were at first submitted to conventional cinecoronaryography and to programmed ventricular stimulation utilizing the S2, S3, S4 protocol, 30 days after infarction. Moreover, patients were submitted to continuous electrocardiographic (Holter system), exercise test, and radioisotopic studies for left ventricle ejection fraction (phase I). The last three studies were subsequently repeated at 6 and 12 months (phases II and III), respectively., Results: All patients had ventricular arrhythmia induced, and according to the kind of response, patients were grouped into: group I--repetitive ventricular response, RVR, nine (33.5%) patients; group II--non sustained ventricular tachycardia. NSVT, eight (29.5%) patients; group III--sustained ventricular tachycardia SVT, ten (37%) patients. The patients of three groups, when submitted to electrocardiographic exercise test and Holter system studies, revealed complex arrhythmias in all phases. One patient of group II suddenly died at home, and another was injured with syncope, whereas in group III, two suddenly died, one at home and the other at the admission to the hospital, after an acute myocardial infarction. All patients but one of group I, who had a non-fatal reinfarction, showed preserved ventricular function., Conclusion: Holter system and electrocardiographic exercises test revealed complex dysrhythmia in the tree phases of the study, independently of the induced response; C--Holter system and electrocardiographic exercise test studies revealed no relation. between sudden death and the kind of ventricular induced response or complex arrhythmia. Ventricular arrhythmia induced with S2, S3 and S4 protocol in patients with preserved ventricular function seems to indicate results without predictive value for cardiac sudden death.