[Chrono-risks in the episodes of fatal pulmonary thromboembolism]

A study on circadian and circannual rhythmicity in the episodes of fatal pulmonary thromboembolism has been conducted in 152 cases. The data demonstrate that the incidence in the episodes of pulmonary thromboembolism, evaluated as hour and day of onset in the clinical symptoms, presents a temporal, both circadian, and circannual distribution. The greater incidence occurs in the morning hours and in the winter season. The rhythmometric analysis by "cosinor" method showed a significant circadian and circannual rhythms in incidence of episodes of fatal pulmonary thromboembolism. The temporal distribution does not seem to be casual, but the effect of interrelationship between exogenous rhythms, such as those in the haemostatic system, endogenous rhythms, such as the cold temperature, and disease. These results demonstrate that the pulmonary thromboembolism is a disease with an high "chrono-risk", i.e. it is an expectable disease in its temporal recurrence.