The effect of provocation on left ventricular (LV) outflow was studied by continuous-wave Doppler echocardiography in 103 nonselected, consecutively enrolled patients with LV hypertrophy (LVH), either due to pressure overload (97 patients) or hypertrophic cardiomyopathy (HCM, 6 patients). In 34 patients with LVH, outflow acceleration (gradients ranging from 18 to 122 mm Hg) was induced or accentuated by the Valsalva maneuver after 1.6 mg nitroglycerine sublingually independent of LVH etiology. Factors associated with LV outflow acceleration were female sex, small body surface area and LV cavity size, increased relative wall thickness, LV contractility, and resting LV outflow velocity, mitral anulus calcifications and systolic anterior movement of the mitral valve. It is concluded that dynamic, intracavity LV gradients are a nonspecific flow abnormality that merit consideration because they can be frequently found in LVH patients.