The common cold is generally mild and self-limiting with most symptoms generally improving in a week. Half of cases go away in 10 days and 90% in 15 days. Severe complications, if they occur, are usually in the very old, the very young, or those who are immunosuppressed.
Types of sick sinus syndrome and their causes include: 1  Sinoatrial block. Electrical signals move too slowly through the sinus node, causing an abnormally slow heart rate. 2  Sinus arrest. The sinus node activity pauses.  Bradycardia-tachycardia syndrome.
Bacteria are the most common direct cause of acute sinusitis. (Other organisms might be the infecting cause in less common cases.) The ability of bacteria or other organisms to infect the sinuses, however, must first be set up by conditions that create a favorable environment in the sinus cavities.