Related Experiment Videos
Influence of age (body size) on the Fontan circulation--analysis by a theoretical model
H Senzaki1, C Naito, T Kobayashi
1Department of Pediatrics and Pediatric Cardiology, Saitama Heart Institutes, Saitama Medical School Hospital, Iruma-Gun, Japan. hsenzaki@saitama-med.ac.jp
Insights
The Fontan operation may be feasible for younger pediatric patients. Smaller body surface area (BSA) significantly increases impedance in Fontan circulation, but this effect is minimal until BSA is below 0.3 m2.
Area of Science:
- Pediatric Cardiology
- Cardiovascular Physiology
- Surgical Innovation
Background:
- The Fontan operation, a complex surgical procedure for single-ventricle congenital heart defects, traditionally has an age criterion of 4 years or older.
- Recent clinical observations suggest that younger patients may also be candidates for the Fontan procedure.
- Age-related changes in systemic vascular properties could impact the Fontan circulation's hemodynamics.
Purpose of the Study:
- To quantify changes in systemic vascular resistance (Rs) and systemic vascular compliance (Cs) with physical development in pediatric patients.
- To analyze the effects of age and body size on Fontan circulation using a cardiovascular model.
- To determine the feasibility of earlier Fontan operations based on hemodynamic factors.
Main Methods:
- Quantified systemic vascular resistance and compliance in 86 pediatric patients without systemic circulation abnormalities.
- Utilized an analytical model of the cardiovascular system to simulate Fontan circulation.
- Analyzed the relationship between body surface area (BSA), vascular compliance, and circulatory impedance.
Main Results:
- Systemic vascular compliance (Cs) significantly decreased as body surface area (BSA) decreased (r=0.81, p<0.001).
- The analytical model demonstrated that decreased BSA led to increased impedance (ventricular afterload) in the Fontan circulation.
- The impact of BSA on impedance was most significant for BSA values below 0.3 m2.
Conclusions:
- Fontan circulation hemodynamics are minimally affected by small BSA (younger age) until BSA approaches infant values.
- The Fontan operation may be feasible at an earlier age than previously recommended, provided hemodynamics are acceptable.
- Understanding age-related changes in vascular properties is crucial for optimizing Fontan procedure timing.
Abstract:
Among the original selection criteria for the Fontan operation, the recommended age at the time of surgery has been 4 years or older, but recent clinical data have indicated the feasibility of this procedure in younger patients. Because age may influence the properties of the systemic vascular bed, changes in systemic vascular resistance (Rs) and systemic vascular compliance (Cs) associated with physical development were quantified in 86 pediatric patients without known abnormalities of the systemic circulation, and the effects of age (body size) on Fontan circulation were then analyzed using an analytical model of the cardiovascular system. As the body surface area (BSA) of the patient decreased, Cs also decreased significantly (r=0.81, p<0.001). Based upon this relationship between BSA and Cs, the analytical model showed that the impedance (ventricular afterload) of the Fontan circulation significantly increased as Cs decreased with the decrease in BSA. Moreover, the increase in impedance in response to changes in heart rate or Rs was inversely proportional to the BSA. However, these findings were significant only when the BSA was below 0.3 m2. Small BSA, or a lower age, has minimal effects on the Fontan circulation until it comes close to the infant value, and thus the Fontan procedure may be feasible much earlier than formerly recommended when the hemodynamics are otherwise acceptable.