Effects of training on the electrophysiologic properties of atrium and accessory pathway in athletes with Wolff-Parkinson-White syndrome.

Twenty-two subjects with Wolff-Parkinson-White (WPW) electrocardiographic pattern performing agonistic physical activity were referred to our laboratory to assess arrhythmogenic risk (group 1). This allowed us to evaluate a less known aspect, namely that of effects of training on the electrophysiologic properties of the atrium and accessory pathway. This was done utilizing a control group of 10 WPW patients who did not perform agonistic physical activity (group 2). All subjects were symptom free, and without signs of associated cardiopathy if we exclude 1 patient of group 1, who presented moderate mitral valve prolapse. Group 1 patients showed significantly higher mean values for basic cycle length (p less than 0.001), atrial effective (p less than 0.04) and functional (p less than 0.02) refractory period, and anterograde effective refractory period of the accessory pathway (p less than 0.02). The different behavior observed in group 1 patients could be explained considering the known influence of training on the equilibrium of the autonomic nervous system. Moreover, it is noteworthy that the two groups did not differ for inducibility of atrial fibrillation (AF). This should be taken into account considering the importance of AF in WPW. In conclusion, our study does not demonstrate any negative electrophysiologic effects of training in patients with WPW.

Relationship between age and anterograde refractoriness of the accessory pathway in Wolff-Parkinson-White patients.

In 22 patients (age range 13-40 years) with Wolff-Parkinson-White ECG pattern without evidence of associated cardiomyopathy we measured the anterograde effective refractory period of the accessory pathway (ERP-AP) by extrastimulus method (at twice diastolic threshold) during atrial pacing (100/min). The ERP-AP range was 220-480 ms. There was a significant direct correlation between age and ERP-AP (r = 0.50, p less than 0.01). An ERP-AP less than or equal to 250 ms was found in 4 patients (age less than or equal to 23 years). This is noteworthy in the light of reports that, over the years: (1) typical Wolff-Parkinson-White ECG signs can disappear and (2) the frequency of tachycardic episodes decreases. Our data suggest a lower risk of high ventricular rates during atrial fibrillation with increasing age.

Atrial electrophysiologic properties of patients with asymptomatic Wolff-Parkinson-White syndrome.

To evaluate the existence of a peculiar atrial electrophysiologic substrate, we studied 18 patients with asymptomatic Wolff-Parkinson-White (WPW) syndrome. These patients were compared with 10 age-matched normal subjects (N). Effective and functional refractory periods were determined at two right atrial sites (high and low in the lateral wall), during atrial pacing (100 min-1) and at twice diastolic threshold. Disperson (D) of effective (ERP) and functional (FRP) refractoriness was evaluated as the difference between refractory periods at the two atrial sites. WPW patients showed significantly lower mean values of effective and functional refractoriness at both atrial sites and significantly higher mean values of D-ERP and D-FRP. Moreover, in calculating the highest normal values of D-ERP and D-FRP (as mean values of N plus 2SD) it was observed that WPW with abnormal values of D showed a statistically (chi 2 test) higher incidence (100%) of induced atrial fibrillation (AF). These findings indicate the existence of both an abnormal atrial electrophysiologic substrate and of a higher vulnerability in WPW. Finally, AF was induced generally at the site with the lower refractoriness (i.e. low lateral site). This should be taken into account when considering how atrial fibrillation can be induced more easily.

Endogenous dopamine (DA) and DA2 receptors: a mechanism limiting excessive sympathetic-adrenal discharge in humans.

We studied the effects of presynaptic dopamine (DA) 2 receptor blockade on the sympathetic-adrenal response to graded exercise in seven normal men. DA2 receptor blockade was achieved by means of domperidone (DMP) administration. The exercise consisted of progressive cycling activity, from 30-80% of the predetermined maximal oxygen consumption for each man. Systolic, diastolic, and mean arterial pressures; heart rate; and plasma norepinephrine (NE), epinephrine (E), PRL, glucose, lactate, FFA, sodium, potassium, cortisol, and PRA were measured at rest, during exercise, and during recovery after placebo or DMP administration. Graded exercise caused significant increases in systolic and mean arterial pressures and plasma NE, E, lactate, sodium, potassium, FFA, cortisol, and PRA. DMP administration before exercise caused a significant increase in plasma PRL (P = 0.0009), a greater increase in plasma NE at the end of the exercise (P = 0.002), and an overall increase in plasma E (P = 0.02) and FFA (P = 0.02) concentrations. These results strongly suggest that endogenous DA limits catecholamine release during sympathetic-adrenal stimulation by activating DA2 receptors.

Ergometric evaluation of physical fitness of athletes affected by mitral valve prolapse: study of 80 cases.

Physical fitness of athletes affected by mitral valve prolapse (MVP) was examined, in order to evaluate the influence of sport activity on the natural history of the disease. Maximal workload, total workload, percentage efficiency (according to Hollmann's formula), double product of maximal cycloergometric stress test performed by 80 athletes (53 male, 27 female, mean age 23.8 yrs) with MVP were considered and compared with the same parameters obtained by 160 (120 male, 40 female) normal athletes (N) matched for age and weight. Moreover, the same ergometric data of two maximal exercise tests, performed by 30 subjects of the MVP group, a mean follow-up period of 2.5 years (range 1-6 years) were compared. No significant difference was found between MVP and N group ergometric data, except for double product, that was significantly lower in MVP group with respect to N group (P less than 0.001). Moreover, no difference was found between MVP with or without mitral regurgitation, and N. No difference was found between the first and the last ergometric test in the follow-up group. In conclusion, our results suggest that athletes with MVP have no reduction of physical fitness. Ergometric follow-up, almost in our cases, does not indicate a negative influence of physical activity on the natural history of the disease.

Long-term follow-up in children without heart disease with ventricular premature beats.

In order to evaluate the significance of premature ventricular beats (PVBs) in childhood, 9 children (mean age 12.8 +/- 2.3 years) without clinical or in noninvasive investigational signs of heart disease, with occasional PVBs detected during early medical control, have been studied over periods ranging from 12 to 68 months. At the beginning and end of the follow-up period all children performed a step test, a maximal cycloergometric exercise test, 24-hour electrocardiographic monitoring, echocardiogram and routine laboratory examinations. While at first control complex PVBs were found in 4 children, at final control only 2 showed complex PVBs, 1 simple PVBs and 1 no PVB. Among the 5 children having simple PVBs at first control, only one showed complex PVBs at the end of the follow-up, with 3 simple PVBs and 1 no PVB. The disappearance of more dangerous PVBs (run of three or more) and also the large variability of arrhythmia (both for its presence and complexity) during the numerous tests, seem to demonstrate that in children with normal hearts the occurrence of PVBs can be considered as benign and free of adverse implications.

Effects of one year of physical training on borderline hypertension: an evaluation by bicycle ergometer exercise testing.

Previous observations have suggested the possibility of separating the borderline hypertensive population into two groups on the basis of blood pressure responses to maximal exercise testing. In order to evaluate the effects of 1 year of physical training on hypertensive subjects, 14 men with resting borderline hypertension and with a normal pressure response to exercise (group I) and 12 with resting borderline hypertension but with an abnormal pressure response to exercise (group II) underwent a maximal bicycle ergometer stress test in a sitting position before and after the training period. In group I, systolic and diastolic blood pressure levels both at rest and during submaximal exercise were significantly reduced after the training period. In group II, resting systolic blood pressure was unchanged, whereas resting diastolic pressure was significantly increased. During submaximal exercise, systolic and diastolic blood pressure showed only mild, nonsignificant differences when compared before and after training. No differences were found during maximal exercise. Blood pressure response to stress testing is useful to identify early stages of the disease and to plan preventive measures consisting of regular physical training either alone or associated with dietary and/or pharmacological treatment.

Long-term favourable effect of nifedipine in primary pulmonary hypertension. Report of a case with hemodynamic evaluation after 3 and after 16 months and with clinical follow-up during 36 months.

The favourable effect of long-term (36 months) treatment with nifedipine in a case of primary pulmonary hypertension is described. While clinical improvement was quick, pulmonary hemodynamic data were unchanged after 3 months of treatment, when acute administration of the drug showed a significant fall in pulmonary resistances. After 16 months of treatment a consistent decrease of pulmonary artery pressure was found, suggesting a selective favourable effect of the drug on the pulmonary circulation. The association with systemic arterial hypertension, whose onset was near contemporaneous with pulmonary hypertension, might indicate a common vasoconstrictive pathogenetic mechanism.