Twenty-four-hour ambulatory blood pressure monitoring in the follow-up of the univentricular heart after Fontan repair

Abstract

Background: In a univentricular heart corrected with a Fontan repair (UVH-F), a single pumping chamber is responsible for both systemic and pulmonary circulations. To evaluate the influence of afterload on cardiac output (CO) of UVH-F, this study aimed at (a) evaluating 24-h ambulatory blood pressure monitoring (ABPM) data of a group of UVH-F patients compared with a control group of healthy individuals (C) and (b) examining possible correlations between afterload measure [elastance (Ea)] derived from ABPM with (i) CO as calculated from pulse pressure and heart rate (ii) cardiac index (CI) as calculated from pulse pressure, heart rate and body surface.

Methods: Ten UHV-F patients (four males, six females, mean age at study: 12.6±0.6 years, and mean time from surgery: 7.2±1.7 years) were enrolled. A 24-h ABPM was performed.

Results: (UVH-F vs. C) Systolic blood pressure (101±3 vs. 112±3 mmHg, P<0.0001); diastolic blood pressure (59±3 vs. 72±3 mmHg, P<0.0001); mean arterial ressure (73±3 vs. 85±3 mmHg, P<0.0001); heart rate (68±6 vs. 87±5 beats/min, P<0.0001); CO (2.85±0.4 vs. 3.48±0.2 l/min, P<0.0001); and CI (2.51±0.2 vs. 2.92±0.1 l/min/m(2), P<0.0001) were determined. In UVH-F, CO was related inversely to E(a) (r=-0.81, P<0.004). CI and E(a) were also related (r=±0.82, P<0.003). CO and time since surgery were inversely related (r=-0.98, P<0.0001).

Conclusion: In UVH-F 24 h, single ventricle afterload and CO are inversely related. When correcting CO for body surface to obtain CI, the graphic representation of their reciprocal relationship appears to be more explanatory for UVH-F haemodynamics.