title: Seasonal variation in thrombogenicity of blood: a word of caution.
abstract: Thrombogenicity of blood is known to have seasonal variations. The clinical implications of seasonal variations in the anticoagulation profile of patients with mechanical valves was assessed. Data of patients implanted with a mechanical heart valve for more than 3 months were collected at follow-up or on presentation to the emergency department. The mean time from the previous follow-up examination was 3.6 +/- 0.3 months. The number of patients with an international normalized ratio >3.5 and the incidence of hemorrhagic events peaked in hottest part of the year (June-July), with 128 cases of prolonged clotting and 43 hemorrhagic events in this period. The number of patients with rapid clotting and the incidence of embolic events peaked in coldest part of the year (December-January), with 120 cases of international normalized ratio <1.5 and 37 embolic events in this period. There was a significant correlation between temperature and thrombogenicity in patients with prosthetic heart valves on long-term anticoagulation.
authors.affiliation: Department of Cardiovascular and Thoracic Surgery, GB Pant Hospital, Maulana Azad Medical College, New Delhi, India. sumit_narang@yahoo.com
authors.forename: Sumit
authors.initials: S
authors.lastname: Narang
authors.forename: Amit
authors.initials: A
authors.lastname: Banerjee
authors.forename: Deepak K
authors.initials: DK
authors.lastname: Satsangi
authors.forename: Mohammad A
authors.initials: MA
authors.lastname: Geelani
mesh_terms: D000925:Anticoagulants / Q000627:therapeutic use; D001777:Blood Coagulation; D004617:Embolism / Q000097:blood / Q000453:epidemiology* / Q000517:prevention & control; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D005500:Follow-Up Studies; D006350:Heart Valve Prosthesis / Q000706:statistics & numerical data*; D006470:Hemorrhage / Q000097:blood / Q000453:epidemiology*; D006801:Humans; D006813:Humidity; D015994:Incidence; D019934:International Normalized Ratio / Q000706:statistics & numerical data*; D012621:Seasons; D013696:Temperature
chemical_list: D000925:Anticoagulants