O2062: Can atrial pacing improve cardiac output in Fontan patients who are in normal sinus rhythm?

Background: Compromised cardiac output (CO) may occur immediately post-operatively and in the long term in patients following the Fontan operation (FO). Atrial pacing (AP) may be a way to increase CO in those patients. The objective of this study was to determine the hemodynamic impact of AP at increasing rates in Fontan patients.

Methods: A pilot study examining the effects of AP at progressively increasing rates was performed in Fontan patients undergoing surveillance cardiac catheterization. After 2 minutes of pacing at each rate, mixed venous (MV) and aortic (Ao) saturations were obtained, and aortic pressure (BP), Fontan pressure (FP) and pulmonary capillary wedge pressure (PCWP) were measured. CO was calculated using the Fick method. The study was ended, when a max. rate of 150 bpm was reached or a significant drop in BP, rise in FP or decrease in CO was observed.

Results: Of the 12 studied patients aged 5-44 years (median 16), 9 (75%) benefited from AP with an initial increase in CO by 6-73% (mean 31%, SD +/- 25%) prior to tachycardia induced decrease (figure 1). In those with pacing-related improvement in CO, FP and PCWP at max. CO was stable or decreased in 8 of 9 patients - FP by 0-31% (mean 10%, SD +/- 11%), PCWP by 0-40% (mean 18%, SD +/- 20%). In one patient, CO increase due to AP was associated with increase in FP and PCWP (figure 2). There were 3 patients in whom AP caused a decline in CO along with increase in FP and PCWP.

Conclusion: Atrial pacing may improve hemodynamics in patients after FO, i.e. increase CO with favorable effects on FP and PCWP when tachycardia is avoided. A larger sample size will be needed to test this hypothesis further. AP could improve hemodynamics after FO immediately post-operatively as well as in the long-term for Fontan failure patients.