Influence of Heart Rate on Hemodynamics in Fontan Circulation

Area of Science:

• Cardiology
• Pediatric Cardiology
• Congenital Heart Disease

Background:

• The standard heart rate (HR) and its impact on Fontan circulation are not well-defined.
• Fontan circulation requires careful hemodynamic management, with HR being a key factor.

Purpose of the Study:

• To determine standard heart rate values in adults with Fontan circulation.
• To investigate the relationship between heart rate and hemodynamic parameters in Fontan patients.
• To compare heart rate profiles between patients with and without pacemakers (PM).

Main Methods:

• Evaluated HR and hemodynamic parameters in 59 adults with Fontan circulation without a pacemaker.
• Compared findings with 15 patients with a pacemaker.
• Measured HR during various activities including sleep, rest, daily activity, and exercise (CPX).

Main Results:

• Established standard HR values for adults with Fontan circulation: ~50 bpm (sleep), ~75 bpm (supine), ~80 bpm (Holter mean), ~85 bpm (sitting), ~140 bpm (max daily activity), ~165 bpm (exercise).
• Higher HR during exercise and greater HR variability (ΔHR) between exercise and sleep were linked to favorable hemodynamics.
• Pacemaker group showed higher sleep HR and lower HR during activities above sitting compared to the non-pacemaker group.

Conclusions:

• Elevated heart rate during physical activity may support optimal Fontan circulation.
• Pacemaker implantation in Fontan patients should consider settings for increased activity HR, narrow QRS duration, and atrioventricular synchrony.