Cardiac rest and reserve function in patients with Fontan circulation

Area of Science:

• Pediatric Cardiology
• Congenital Heart Disease
• Cardiac Physiology

Background:

• Mechanisms of cardiac performance in Fontan physiology are not fully understood.
• Adverse outcomes after Fontan surgery require further investigation into underlying cardiac limitations.

Purpose of the Study:

• To systematically evaluate cardiac rest and reserve function in Fontan physiology.
• To identify inherent limitations in the Fontan circulation.

Main Methods:

• Compared 17 Fontan patients with 20 controls.
• Assessed baseline ventricular contractility, diastolic function, and loading factors.
• Examined responses to increased heart rate (HR) and beta-adrenergic stimulation using ventricular pressure-area relationships.

Main Results:

• Fontan patients showed minimal baseline abnormalities but decreased cardiac index with increased afterload.
• Fontan circulation exhibited limited inotropic response and worsened diastolic filling with increased HR.
• Beta-adrenergic reserve was significantly decreased in Fontan patients due to limited preload reserve.

Conclusions:

• Impaired ventricular-vascular interaction and limited cardiac augmentation impact cardiac output and exercise capacity in Fontan patients.
• These findings suggest mechanisms for adverse outcomes post-Fontan surgery.
• Developing medical interventions to overcome inherent Fontan circulation limitations is crucial for improving long-term prognosis.