Atrial activation during sinus rhythm in patients with rheumatic and non-rheumatic paroxysmal atrial fibrillation. Frequency-domain analysis using signal-averaged electrocardiography.

OBJECTIVE: Using P-wave signal-averaged electrocardiography, we assessed the patterns of atrial electrical activation in patients with idiopathic atrial fibrillation as compared with patterns in patients with atrial fibrillation associated with structural heart disease. METHODS: Eighty patients with recurrent paroxysmal atrial fibrillation were divided into 3 groups as follows: group I - 40 patients with atrial fibrillation associated with non-rheumatic heart disease; group II - 25 patients with rheumatic atrial fibrillation; and group III - 15 patients with idiopathic atrial fibrillation. All patients underwent P-wave signal-averaged electrocardiography for frequency-domain analysis using spectrotemporal mapping and statistical techniques for detecting and quantifying intraatrial conduction disturbances. RESULTS: We observed an important fragmentation in atrial electrical conduction in 27% of the patients in group I, 64% of the patients in group II, and 67% of the patients in group III (p=0.003). CONCLUSION: Idiopathic atrial fibrillation has important intraatrial conduction disturbances. These alterations are similar to those observed in individuals with rheumatic atrial fibrillation, suggesting the existence of some degree of structural involvement of the atrial myocardium that cannot be detected with conventional electrocardiography and echocardiography.

Higher incidence of catheter-related infections in a tropical climate.

Catheter-related infections (CRIs) have become a prominent morbidity factor in continuous ambulatory peritoneal dialysis (CAPD). To confirm a clinical impression that CRI rates in our population (n = 80, 1080 patient-months) were unusually high, a retrospective study was performed. In addition, data from adult patients treated for at least 12 months were analyzed (n = 28, 325 patient-months) to determine if climate conditions could account for our findings. Comparisons were made between CRI rates during months with a mean maximal temperature of 32 degrees C or higher (hot season) and CRI rates during months with a mean temperature lower than 28 degrees C (control season). Two-cuff Tenckhoff catheters were used on 68 occasions and the Swan neck Missouri catheter 2 on 20 occasions. Main CAPD systems were the O-set (n = 48) and the disposable Y-set (n = 35). A total of 139 CRI episodes were recorded with a rate of 1/8 patient-months. A CRI was implicated as a causative factor in 18 of 69 episodes of peritonitis (26%) and in 13 of 27 catheter losses (48%). CRI rates were similar when comparing either Swan neck versus Tenckhoff catheters (1/7 and 1/8 patient-months) or the O-set versus disposable Y-set (1/7 and 1/10 patient-months). Most importantly, a significantly higher incidence of CRI was found during the hot seasons in comparison to the control seasons (1/9 vs 1/19 patient-months, p < 0.05, one-way signed rank test). Our data suggest that a hot climate can adversely affect the rate of CRIs.