A new sign of sympathetic neurocirculatory failure: premature ventricular contraction as a "one-beat Valsalva maneuver".

Sympathetic neurocirculatory failure (SNF) features orthostatic hypotension and abnormal beat-to-beat blood pressure (BP) responses to the Valsalva maneuver. This article describes a new sign of SNF, based on changes in BP after premature ventricular contractions (PVCs). Records of supine beat-to-beat BP at rest were reviewed from 22 patients with SNF and 52 control subjects. Records were also taken during intravenous infusion of the ganglion blocker trimethaphan from 38 control subjects. In all 10 control subjects who had PVCs, after the postextrasystolic beat, mean arterial pressure increased progressively to levels higher than before the PVC, peaking at about the eighth beat. In contrast, in all 13 patients with SNF who had PVCs, after the postextrasystolic beat, BP decreased to less than baseline and then increased gradually back to baseline. In all 3 control subjects who had at least one PVC before trimethaphan infusion and another during trimethaphan infusion, the post-PVC pressure pattern during trimethaphan infusion resembled that in SNF patients. Because of a brief increase in sympathetic cardiovascular outflows, after a PVC, BP increases progressively to greater than pre-PVC values, mimicking the pressure overshoot after release of the Valsalva maneuver. Just as the absence of the overshoot of BP after release of the Valsalva maneuver supports a diagnosis of SNF, so does the absence of the overshoot after a PVC.