Sport modality affects bradycardia level and its mechanisms of control in professional athletes.

We investigated the influence of sport modalities in resting bradycardia and its mechanisms of control in highly trained athletes. In addition, the relationships between bradycardia mechanisms and cardiac structural adaptations were tested. Professional male athletes (13 runners, 11 cyclists) were evaluated. Heart rate (HR) was recorded at rest on beat-to-beat basis (ECG). Selective pharmacological blockade was performed with atropine and esmolol. Vagal effect, intrinsic heart rate (IHR), parasympathetic (n) and sympathetic (m) modulations, autonomic influence (AI) and autonomic balance (Abal) were calculated. Plasmatic norepinephrine (high-pressure liquid chromatography) and cardiac structural adaptations (echocardiography) were evaluated. Runners presented lower resting HR, higher vagal effect, parasympathetic modulation (n), AI and IHR than cyclists (P<0.05). Abal, sympathetic modulation (m) and norepinephrine level were similar within athletes regardless of modality. The cardiac chambers were also similar between runners and cyclists (P=0.30). However, cyclists displayed higher septum and posterior wall thickness than runners (P=0.04). Further analysis showed a trend towards inverse correlation between IHR with septum wall thickness and posterior wall thickness (P=0.056). Type of sport influences the resting bradycardia level and its mechanisms of control in professional athletes. Resting bradycardia in runners is mainly dependent on an autonomic mechanism. In contrast, a cyclist's resting bradycardia relies on a non-autonomic mechanism probably associated with combined eccentric and concentric hypertrophy.

Diagnostic value of the tilt-table test for the assessment of syncope in children and adolescents.

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.

Hormonal and cardiovascular reflex assessment in a female patient with pure autonomic failure.

We report the case of a 72-year-old female with pure autonomic failure, a rare entity, whose diagnosis of autonomic dysfunction was determined with a series of complementary tests. For approximately 2 years, the patient has been experiencing dizziness and a tendency to fall, a significant weight loss, generalized weakness, dysphagia, intestinal constipation, blurred vision, dry mouth, and changes in her voice. She underwent clinical assessment and laboratory tests (biochemical tests, chest X-ray, digestive endoscopy, colonoscopy, chest computed tomography, abdomen and pelvis computed tomography, abdominal ultrasound, and ambulatory blood pressure monitoring). Measurements of catecholamine and plasmatic renin activity were performed at rest and after physical exercise. Finally the patient underwent physiological and pharmacological autonomic tests that better diagnosed dysautonomia.

Comparison of risk of orthostatic hypotension in elderly depressed hypertensive women treated with nortriptyline and thiazides versus elderly depressed normotensive women treated with nortriptyline.

This is a nonblind, case-controlled study comparing the risk of orthostatic hypotension (OH) in 2 groups of elderly depressed women: 22 normotensive and 21 hypertensive patients receiving thiazides. Blood pressure measurements and tilt-table tests produced similar results: increased drop in systolic blood pressure (SBP) after standing (p <0.001), with no significant differences between the groups (p = 0.523). There were no changes on diastolic blood pressure (DBP) after standing, or in SBP or DBP at rest. Dizziness was reported by 23 subjects (53.5%) before treatment, and by 16 subjects (38.1%) at week 8. Complaints of dizziness were not associated with OH (Kappa = 0.07).

Síncope / Syncope

Síncope é um evento clínico bastante comum, de difícil diagnóstico, muitas vezes incapacitante e, em diversas situaçöes, de mau prognóstico. Muitas são as possíveis etiologias e o principal papel do médico é distinguir causas benignas daquelas de mau prognóstico. Na maioria das vezes, muitos testes dispendiosos têm sido realizados, sem que se atinja o sucesso esperado. O objetivo deste artigo será determinar os principais mecanismos fisiopatológicos da síncope e qual a melhor estratégia para que se determine a etiologia e, portanto, a terapêutica ideal.

[Type I atrial flutter radiofrequency ablation. Importance of bidirectional block of isthmus between the inferior vena cava and of tricuspid valve ring]. / Ablação com radiofreqüência do Flutter atrial tipo I. Importância do bloqueio bidirecional do istmo entre a veia cava inferior e o anel da valva tricúspide.

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.

[The pseudo-pacemaker syndrome]. / Pseudo-síndrome de marcapasso.

We describe three cases of the pseudo-pacemaker syndrome. One of them due to selective fast pathway fulguration of atrioventricular nodal reentrant tachycardia and two others have occurred in spontaneous form. All cases were related with the presence of first-degree atrioventricular block and sinus node tachycardia. The treatment was done with complete atrioventricular block induction catheter ablation and permanent pacemaker implantation in two patients. In conclusion, the procedure of radiofrequency ablation to control AV nodal reentry tachycardia must preserve the fast nodal pathway in order to avoid the pseudo-pacemaker syndrome and this syndrome can spontaneously occur and must be considered during investigation of etiology of syncope.

[Reproducibility of head-up tilt test in patients with neurocardiogenic syncope]. / Reprodutibilidade do teste de inclinação em pacientes com síncope neurocardiogênica.

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.

[Diagnostic value of the tilt test in the evaluation of syncope of unknown origin. Preliminary results]. / Valor diagnóstico do teste de inclinação na avalicção da síncope de origem indeterminada. Resultados preliminares.

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.

[Myocardial dysfunction secondary to persistent tachycardia]. / Disfunção miocárdica secundária à taquicardia persistente.

This study demonstrates the presence of variable degrees of reversible ventricular dysfunction in five patients with incessant atrioventricular tachycardia (IAVT) submitted to surgical ablation of the anomalous pathway. The patients were three females and two males, with age ranging from four to 39 years (mean 15.2). Preoperative EKG presented persistent tachycardia with narrow QRS and RP greater than PR in every case. The P wave was negative in leads D2, D3, AVF from V2 to V6. The 24 hours Holter monitoring demonstrated IAVT rhythm with few sinus beats. The heart rate variated from 140 to 190 bpm (mean 158 bpm). The echocardiogram ejection fraction ranged from 33% to 59% (mean 49.6%). The left ventricular diastolic diameter varied from 47 to 66 mm (mean 53.8). The chest X-ray showed moderate heart enlargement in two patients and mild enlargement in one. All the patients were refractory to isolated or associated antiarrhythmic drugs. Postero-septal anomalous A-V pathway (with exclusively slow retrograde conduction, was demonstrated by electrophysiologic study. After surgery every patient was asymptomatic without medication. Permanent sinus rhythm with heart rate of 62 to 100 bpm (mean 78.4 bpm) in a four months to two years follow-up. The postoperative echocardiogram ejection fraction ranged from 63% to 81% (mean 71.6%) and the left ventricular diastolic diameter was 42 to 57 mm (mean 48.2 mm). The heart area was normal in four patients and mildly increased in one patient. Thus, persistent increase in heart rate induces variable degrees of reversible myocardial dysfunction.