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The recent development of computer technology has made it possible to simulate the hemodynamics of congenital heart diseases on a desktop computer. However, multi-scale modeling of the cardiovascular system based on computed tomographic and magnetic resonance images still requires long simulation times. The lumped parameter model is potentially beneficial for real-time bedside simulation of congenital heart diseases. In this review, we introduce the basics of the lumped parameter model (time-varying elastance chamber model combined with modified Windkessel vasculature model) and illustrate its usage in hemodynamic simulation of congenital heart diseases using examples such as hypoplastic left heart syndrome and Fontan circulation. We also discuss the advantages of the lumped parameter model and the problems for clinical use.

Primary acute sympathetic activation (PASA) can increase arterial pressure (AP). Under this situation, the kidneys may receive mutually opposing influences from sympathetic activation: a direct anti-diuretic effect via the renal innervation and pressure diuresis. We examined whether PASA would reduce urine output regardless of the AP elevation. We also examined the impact of renal denervation (RDN) on urine output during PASA. The experiment was performed on rats 3 to 9 days after unilateral RDN (n = 10). Under anesthesia, systemic sympathetic nerve activity (SNA) was varied over a wide range via the carotid sinus baroreflex. The slope of urine flow versus SNA was positive (0.252 ± 0.052 μL•min −1 •kg −1 • % −1) on the intact side, and it was greater on the denervated side (0.331 ± 0.069 μL•min −1 •kg −1 • % −1 , P < 0.05). In conclusion, urine output change was an effect of elevated AP during PASA. Nevertheless, RDN was able to augment pressure diuresis during PASA.

Background Liver cancer (LC) is a serious late complication after the Fontan operation. However, the incidence, predictors, and prognosis remain unknown. The purpose of our study was to determine these clinical characteristics. Methods and Results We assessed liver function in 339 consecutive patients who had undergone the Fontan procedure from 2005 to 2019. LC was histologically diagnosed in 10 patients after a median period of 2.9 years (range: 0.3–13.8; median age: 29.9 years [range: 14.4–41.5 years]; overall median post–Fontan procedure follow‐up: 25.6 years [range: 13–32.1 years]), and the annual incidence was 0.89%. Over the entire post‐Fontan follow‐up period, the annual incidences of new‐onset LC in the second, third, and fourth decades were 0.14%, 0.43%, and 8.83%, respectively. The patients with LC had longer follow‐up periods, higher levels of AFP (α‐fetoprotein), and higher values of liver fibrosis indices ( P <0.01–0.0001). Moreover, all indices were predictive of new‐onset LC ( P <0.01–0.0001). The LC treatments were surgical resection (n=3), transarterial chemoembolization (n=3), radiofrequency ablation (n=2), and hospice care (n=2). During a median follow‐up of 9.4 months, 4 patients died; the survival rate at 1 year was 60%, and it was better among asymptomatic patients ( P <0.01). Conclusions The LC incidence rapidly increased ≥30 years after the Fontan procedure, and liver fibrosis indices and AFP were predictive of new‐onset LC. These LC‐predictive markers should be monitored closely and mandatorily for early LC detection and better prognosis.