EFFECT OF ORTHOSTATIC CHANGE ON HEMODYNAMIC STABILITY IN ORTHOTOPIC HEART TRANSPLANT RECIPIENTS.
Contributors: University of California, Los Angeles.
Published: 1994
Number of pages: 216
Subjects: Health Sciences, Nursing.; Health Sciences, Medicine and Surgery.
Description: A study was conducted to compare the effects of passive upright positioning in orthotopic heart transplant recipients and in normal subjects. Thirty-four heart transplant recipients, 16 who were five months or less from transplantation and 17 who were one year or more from transplantation, were studied along with 16 healthy volunteers matched to recipient age.

All participants performed two tests of autonomic function. The participants underwent a 30 minute supine baseline period, followed by 45 minutes of passive upright positioning and 30 minutes of supine recovery. The following variables were measured every five minutes: heart rate (HR), cardiac output (CO) and stroke volume (SV), mean arterial pressure (MAP). Systemic vascular resistance (SVR) was calculated for each time point. Prior to position changes, blood specimens for catecholamine levels were drawn from venous intravenous catheters. Baseline HR (p $<$.001), SV (p =.000), diastolic blood pressure (p =.001), and MAP (p =.002) differed between transplant groups and the control group.

HR acceleration with handgrip differed among groups, with HR acceleration found in the late group (p =.001) and in the control group (p $<$.001), but not in the early group. During deep breathing, HR variability was greater in the control group than in either transplant group (p $<$.001).

Repeated measures analysis of variance revealed main effects for group (p =.000), time (p =.009), and position (p $<$.001) factors. Interaction effects were found for group and position (p $<$.001) and for time and position (p $<$.001). Position differences varied by group for HR, with greater acceleration in the control group and the late group than in the early group (p =.028), and for SV, with a smaller decrease in both transplant groups than in the control group (p $<$.001). Time differences varied by group for HR (p $<$.001) and SV (p $<$.001).

These findings provide new evidence of stress-induced HR acceleration among long-term transplant survivors. The evolution of HR responsiveness after transplantation is consistent with sympathetic reinnervation, but definitive conclusions regarding the etiology of this phenomenon await further investigation.
Notes: Source: Dissertation Abstracts International, Volume: 55-11, Section: B, page: 4785.

Thesis (D.N.SC.)--UNIVERSITY OF CALIFORNIA, LOS ANGELES, 1994.

School code: 0031.