Exercise-dependent changes in ventricular–arterial coupling and aortopulmonary collateral flow in Fontan patients: a real-time CMR study

Abstract

Aims Inefficient ventricular–arterial (V–A) coupling has been described in Fontan patients and may result in adverse haemodynamics. A varying amount of aortopulmonary collateral (APC) flow is also frequently present that increases volume load of the single ventricle. The aim of the study was to assess changes in V–A coupling and APC flow during exercise CMR. Methods and results Eighteen Fontan patients (age 24 ± 3 years) and 14 controls (age 23 ± 4 years) underwent exercise CMR using a cycle ergometer. Ventricular volumetry and flow measurements in the ascending aorta (AAO), inferior (IVC), and superior (SVC) vena cava were assessed using real-time sequences during stepwise increases in work load. Measures of systemic arterial elastance Ea, ventricular elastance Ees, and V–A coupling (Ea/Ees) were assessed. APC flow was quantified as AAO − (SVC + IVC). Ea remained unchanged during all levels of exercise in both groups (P = 0.39 and P = 0.11). Ees increased in both groups (P = 0.001 and P < 0.001) with exercise but was lower in the Fontan group (P = 0.04). V–A coupling was impaired in Fontan patients at baseline (P = 0.04). Despite improvement during exercise (P = 0.002) V–A coupling remained impaired compared with controls (P = 0.001). Absolute APC flow in Fontan patients did not change during exercise even at maximum work load (P = 0.98). Conclusions Inefficient V–A coupling was already present at rest in Fontan patients and aggravated during exercise due to a limited increase in ventricular contractility which demonstrates the importance of a limited functional reserve of the single ventricle. APC flow remained unchanged suggesting no further increase in volume load during exercise.

Exercise catheterization in adults post‐Fontan with normal and abnormal haemodynamic criteria: Insights into normal Fontan physiology

“…In contrast to that notion, exercise SVi did not significantly differ between Group II and NCD patients. This agrees with the observations in adults post‐Fontan undergoing exercise cardiac magnetic resonance imaging 22 . Moreover, Group II demonstrated appropriate Qs response to exercise.…”

“…This agrees with the observations in adults post-Fontan undergoing exercise cardiac magnetic resonance imaging. 22 Moreover, Group II demonstrated appropriate Qs response to exercise. Therefore, the most remarkable haemodynamic difference in Groups II patients compared to NCD appeared to be the degree of systemic venous hypertension and arterial desaturation.…”

“…Resting cardiac catheterization data demonstrated higher haemoglobin levels (14.5 [13.5-15.3] vs. 12.9 [12-13.9] g/dl, p = 0.007) and lower arterial O 2 saturation (94% [93-95] vs. 97% [96-99], p < 0.0001) in Group II compared to NCD. Group II had higher SVC (11 [9-11] At peak exercise, SVC pressures were higher (16 [14-22.5] vs. 5.5 [3-7.3] mmHg, p < 0.001) and PA pressures lower (16 [14.5-19.5] vs. 23 [20][21][22][23][24][25] mmHg, p < 0.001) in Group II than in NCD patients. There was no difference in PAWP (12 [8][9][10][11][12][13][14]…”