Background: Maintaining higher than normal central venous pressure (CVP) by altering venous characteristics is the body’s adaptive response allowing the establishment of Fontan circulation. However, this can be a major cause of Fontan complications during a long period of time. We previously demonstrated that aggressive arterial and venous vasodilator therapy in patients after Fontan surgery contributed to achieving very low CVP (generally less than 10 mmHg) at the time of catheter examination one year after surgery. In the present study, we applied this strategy (Super-Fontan strategy) to chronic Fontan patients and examined whether or not it could reduce CVP while preserving cardiac output.
Methods: Nitroglycerin (0.8-2.5 mg/kg) was newly introduced as a venous dilator in 29 Fontan patients (8.2 ± 3.5 years old) with a mean postoperative period of 6.2 ± 0.5 years. Enalapril 0.1-0.2 mg/kg was concurrently administered to those who were not taking an angiotensin-converting enzyme inhibitor. Changes in hemodynamics were evaluated 3-6 months after the introduction of this strategy.
Results: CVP significantly decreased from 13.6 ± 2.6 mmHg to 9. 4 ± 2.2 mmHg after strategy introduction (p < 0.0001). In addition, the venous capacitance, calculated as the ratio of circulating blood volume (measured using indocyanine green) to mean circulatory filling pressure (measured using peripheral vein tourniquet), significantly increased after introduction of the S-Fontan Strategy (25.8 ± 9.6%, p < 0.0001), supporting the beneficial effect of this strategy on CVP reduction. Furthermore, there was no decrease in cardiac output after introduction of the strategy; instead, cardiac output was actually rather increased due to the significant afterload reduction (p < 0.001).
Conclusion: Venous capacitance is considered to be an important target for maintaining good circulation in postoperative Fontan patients. Our results suggest that the S-Fontan Strategy can significantly reduce CVP in chronic Fontan circulation within 10 years after surgery, leading to improved outcomes for Fontan patients. We believe that the findings of this study warrant further investigation in a prospective setting.