The periodicity of vascular access thrombosis

A periodicity has been observed in thrombotic events that occur in a variety of vascular beds. There also has been a recent suggestion that there is an increased failure of hemodialysis vascular accesses due to thrombosis during the summer months. We reviewed the last 949 episodes of vascular access thrombosis and found no seasonal pattern, but a weekly pattern was noted that corresponded to the patients' dialysis schedule. That pattern was apparently due to our technique of observation and not due to any intrinsic periodicity in the thrombosis itself. We find no evidence to support the belief in any intrinsic periodicity in hemodialysis vascular access thrombosis and since the thrombotic event itself is usually asymptomatic, any accurate assessment of a diurnal or circumseptan pattern is not possible under ordinary clinical conditions.