[Hemodynamic response to somatostatin at rest and during sympathetic activation in idiopathic orthostatic hypotension].

Idiopathic orthostatic hypotension (IOH) represents a degenerative disorder of the peripheral nervous system characterized by low values of arterial blood pressure during orthostatism, with reduction in serum catecholamines. Since treatment of symptomatic IOH has been unsatisfactory till now, we studied the hemodynamic response to somatostatin (S) (Octreotide, 100 micrograms sc) at rest (R) and during sympathetic activation (tilting, T) by means of 2D and/or color Doppler echocardiography, in 5 ambulatory IOH patients (4M, 1F; aged 65 +/- 5 years), with simultaneous recording of blood pressure and heart rate. Post-S, an increased blood pressure was evident during T without heart rate modifications (pre- vs post-S, SAP: 92 +/- 9 vs 148 +/- 12; DAP: 61 +/- 4 vs 90 +/- 9 mmHg; p less than 0.05), while systolic echo parameters did not change significantly. Doppler aortic velocity curve showed during T a reduction of Vmax (pre- vs post-S: 0.98 +/- 0.09 vs 0.73 +/- 0.03 m/s; p less than 0.05) and of cardiac output, due to unchanged preload. Pre-S, at rest, Doppler mitral velocity curve presented a normal E/A ratio as in normal subjects, with a reduced E peak and an increased A peak post-S, indirect signs of increased afterload. Pre-S, E and A peak velocities underwent progressive decrease during T, markedly more evident post-S. Total peripheral resistance, at rest and during T, increased post-S too (pre- vs post-S, rest: 2406 +/- 267 vs 3162 +/- 599; T: 1634 +/- 201 vs 2784 +/- 425 dyne*s/cm-5; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)