CHANGES OF CIRCADIAN BLOOD-PRESSURE PATTERNS AFTER HEMODYNAMIC AND THROMBOEMBOLIC BRAIN INFARCTION

Background and Purpose We investigated the changes of circadian blood pressure patterns after thromboembolic and hemodynamic brain infarctio n and evaluated the relation between circadian blood pressure variatio n, infarct location, and activation of the autonomic nervous system af ter thromboembolic stroke. Methods Repeated 24-hour blood pressure mea surements were performed in 45 patients with proven first-ever brain i nfarctions of different origins. Evaluation of serum norepinephrine co ncentration, prolongation of the QT interval, and degree of cardiac ar rhythmias were used to determine the extent of sympathetic activation after thromboembolic stroke. Results Whereas circadian blood pressure variation was significantly increased after hemodynamic infarction com pared with a control group (diastolic, -25.2+/-4.5% versus -13.8+/-6.5 %; P<.005), a clearly reduced variation was observed after thromboembo lic infarction (diastolic, -5.2+/-6.9%). Blood pressure variation was positively related to serum norepinephrine concentration (r=.79; P<.01 ) after thromboembolic infarction. Patients with involvement of the in sular cortex showed a nocturnal rise of blood pressure significantly m ore frequently (66.7% versus 11.8%; P<.005) and had higher norepinephr ine levels (540+/-110 pg/mL versus 290+/-178 pg/mL; P<.01) than patien ts without insular cortex infarction, indicating increased sympathetic activity. This was associated with a significantly more frequent occu rrence of QT prolongation and cardiac arrhythmias. Conclusions The obs erved differences in circadian blood pressure patterns may (1) help to distinguish the pathophysiological basis of the stroke, (2) help to e xplain worsening in some cases of hemodynamic stroke, (3) confirm the importance of the insular cortex for sympathetic activation, and (4) i dentify subgroups of patients with increased risk of myocardial infarc tion and arrhythmia.