Clinical significance of natriuretic peptides in patients with aneurysmal subarachnoid hemorrhage]

Hyponatremia and hypovolemia following aneurysmal subarachnoid hemorrhage (SAH) might be speculated by exaggerated secretion of natriuretic peptides and resulted ischemic sequela caused by cerebral vasospasm. We measured serum concentration of natriuretic peptides and investigated their influence on post-SAH hyponatremia. Among 49 patients of SAH, their plasma concentration of the natriuretic peptides (atrial natriuretic peptide: ANP and brain natriuretic peptide: BNP) were measured at the day of ictus and 7th day of SAH. The correlation between concentration of natriuretic peptides and location of aneurysm, severity of SAH, incidence of hyponatremia and symptomatic vasospasm were elucidated. The plasma concentration of ANP did not alter on admission and 7th day post SAH, whereas that of BNP increased in the patients with moribund SAH and those with ruptured A-com aneurysm. The initial increase of BNP following SAH could be attributed to direct damage of SAH on the hypothalamus. Hyponatremia and symptomatic vasospasm tended to occur in the patients who had persistent increase of plasma BNP concentration during one week post SAH. Therapeutic intervention to maintain normonatremia by fluid-management decreased occurrence of symptomatic vasospasm, even though patients with increased plasma BNP concentration. It might be concluded that increased secretion of BNP following SAH is caused by direct effect to the hypothalamus and prolonged hyper secretion of BNP resulted hyponatremia, hypovolemia and exaggerated symptomatic vasospasm.