The objective of this study was to assess hemodynamic responses and baroreflex sensitivity (BRS) indexes during Valsalva maneuver (VM) and head-up tilt (HUT) testing in orthostatic intolerance (OI). Patients with neurogenic orthostatic hypotension (NOH, n = 26), postural tachycardia syndrome ( n = 26) and symptomatic OI ( n = 14) were compared with healthy population (control, n = 107) and inappropriate sinus tachycardia ( n = 7). Hemodynamic assessment included patterning and quantification with vagal and adrenergic BRS (BRSa/BRSa1). In NOH, cardiovagal systolic blood pressure (SBP) decrements in VM and HUT were correlated ( r = 0.660, P < 0.001); a “V” pattern of VM indicated α-BRSa failure. Yet BRSa1 did not reveal changes vs. control ( P > 0.05) or was not applicable in 60% of NOH. In symptomatic OI, compared with control, cardiovagal SBP decrements were larger ( P < 0.05); higher BRSa1 contradicted higher adrenergic index (Composite Autonomic Severity Score). Overshoot in phase IV dipped below baseline or dropped ≥ 10 mmHg over 8 s in postural tachycardia syndrome (“N” pattern), but by 3 s in inappropriate sinus tachycardia (“M” pattern). Visualization of distinct VM patterns allows primary evaluation of autonomic dysfunction and differentiation of the various forms of OI. BRSa1 evaluation is compromised by pathological SBP patterns. VM patterning is a valuable nonpostural supplement to HUT capable of detecting and differentiating OI.
Management of Postural Tachycardia Syndrome, Inappropriate Sinus Tachycardia and Vasovagal Syncope
