Predicting of postoperative cardiac events using ambulatory ECG monitoring prior to abdominal aortic surgery.

OBJECTIVES: The purpose of this study was to estimate the value of preoperative electrocardiographic (ECG) monitoring in predicting postoperative cardiac events in patients undergoing abdominal aortic surgery. DESIGN: A prospective open study. SETTING: University Hospital. MATERIALS: One hundred consecutive patients were studied before aortic or aortofemoral surgery by ambulatory ECG monitoring for 24 hours. CHIEF OUTCOME MEASURES: An ischaemic episode by ECG criteria was defined as a > or = 1 mm horizontal or downsloping ST segment depression measured 60 msec after the J point and persisting for at least 40 sec. MAIN RESULTS: Twenty-four patients had preoperative ambulatory ischaemia. Twenty patients had postoperative cardiac events including three with fatal myocardial infarction, one with a nonfatal infarction, eight with unstable angina, three with pulmonary oedema and five with atrial fibrillation. Sixteen out of 24 (67%) patients with ambulatory ischaemia had postoperative cardiac events (p < 0.01). Only four events occurred among 76 patients without ischaemia (p < 0.005). The sensitivity of ambulatory ischaemia predicting cardiac events was 80% with a specificity of 90%, the predictive value of ischaemia was 67% and the predictive value of a negative result was 95%. CONCLUSIONS: Preoperative ECG monitoring for myocardial ischaemia could non-invasively identify patients at high risk for postoperative cardiac morbidity and mortality after vascular surgery.

Rapid eye movement sleep deprivation depresses plasma FSH and LH in castrated rats.

In castrated Wistar rats four days of Rapid Eye Movement sleep (REMs) deprivation by the cuff pedestal method induced decrements in plasma LH and FSH. The adenohypophyseal levels of these hormones were decreased in the REMs-deprived rats and in the control rats kept on pedestals with the supporting cuff in the elevated position as compared with the home-cage control rats. The results are discussed in terms of regional brain metabolic activity and transmission.

Spectral properties of light affect plasma and pituitary gonadotropins in male rats.

In order to find out whether different light spectra have any role in regulating the gonadotropin levels in male rats, we compared the 24-hour patterns of plasma and pituitary gonadotropins in rats kept for 7 days in natural or in cool white artificial lighting (exp. I). The intensity and periodicity of the two lighting conditions were adjusted as similar as possible. Further, we measured plasma and pituitary gonadotropins in the middle of the light period and in the middle of the dark period in rats kept for 7 days under artificial lightings of three different spectra (exp. II). In both experiments, in all lighting conditions we found higher plasma levels of LH and FSH during the dark than the light period. The differences were statistically significant only when the illumination contained more long and/or short wavelengths than the usual cool white laboratory lighting. The pituitary contents of gonadotropins were not found to vary with the periodicity of lighting. In the 24-hour patterns the overall plasma levels were higher and the pituitary contents of gonadotropins lower in natural lighting than in cool white lighting. It was concluded that the spectral properties of light influence the secretion of gonadotropins in male rats, but the mechanism involved remains to be clarified.