Cardiovascular consequences of clinical stroke.

Abstract

In clinical stroke cardiovascular abnormalities are frequently neglected although they occur more often than it is generally assumed. However, cardiac arrhythmias, pathological ECG findings, and changes of circadian blood pressure patterns are significantly increased in patients with acute cerebrovascular lesions and are associated with an increased mortality. Several clinical studies have shown that cerebral infarctions may cause different cardiovascular abnormalities depending on the location and the size of the stroke. Hereby, the prolongation of the QT interval and the expansion of the QRS-complex as the most frequent ECG abnormalities are regarded as indicators of the electrical instability of the ventricular myocardium. Furthermore, cardiac enzyme increases are interpreted as an indicator of myocardial damage during the acute phase after cerebral ischaemia. Since the autonomic nervous system plays a major role in the regulation of blood pressure, alterations of sympatho-adrenergic activity can also affect the diurnal blood pressure profile. Some studies report frequent changes of the circadian blood pressure patterns with a decreased night-time blood pressure decline or a pathological night-time blood pressure elevation. Several studies proved the importance of infarct location. The insular cortex in particular has an important role in the genesis of the pathological activation of the sympathetic nervous system. Hence, a highly significant relationship between the extent of circadian blood pressure variation and percentage insular infarction could be found. Some findings implied that the mechanism of cardiovascular instability following stroke relates to the disinhibition of the insular cortex and a reacting augmentation of the sympathetic tone. A further important aspect is given by the strong evidence that sympathetic activation ] is lateralized following hemispheric brain infarction. Accordingly, patients with a right-sided hemispheric infarction showed a significantly diminished circadian blood pressure variation as compared with patients with left-sided hemispheric infarction. The results in patients with brain stem infarction were heterogeneous. On the one hand, patients with brain stem infarction had substantially higher mean plasma norepinephrine levels than did patients with hemispheric infarction; on the other hand, hemispheric lesions were associated with a significantly higher incidence of cardiac arrhythmias when compared to patients with brain stem infarction.