Dependency of blood pressure upon cardiac filling in patients with severe postural hypotension.
Autonomic denervation of the vascular bed results theoretically in a stronger dependency of blood pressure upon intravascular volume, and the study described aimed at an investigation of the relation between cardiac filling and arterial blood pressure in patients with severe postural hypotension. Seven patients were studied during head-up tilt at three different tilt angles using intra-arterial blood pressure recordings and estimates of left ventricular volumes by radioisotope ventriculography. Blood pressure fell dramatically during head-up tilt due to reductions in cardiac output unopposed by vasoconstriction. The reduction in cardiac output resulted from reductions in left ventricular end-diastolic volumes with unchanged left ventricular ejection fractions and only moderate increments in heart rate. The study was demonstrated that blood pressure is strongly dependent upon cardiac filling in severe autonomic dysfunction, and that volume expansion is an important measure against postural hypotension.
Mehlsen
J
J
Department of Clinical Physiology & Nuclear Medicine, Frederiksberg Hospital, University of Copenhagen, Denmark.
Haedersdal
C
C
Stokholm
K H
KH
D000368:Aged; D000369:Aged, 80 and over; D001341:Autonomic Nervous System / Q000503:physiopathology; D001794:Blood Pressure / Q000502:physiology*; D003971:Diastole / Q000502:physiology*; D006801:Humans; D007024:Hypotension, Orthostatic / Q000503:physiopathology*; D008875:Middle Aged; D009200:Myocardial Contraction / Q000502:physiology