• cardiac surgery outcomes
• congenital heart disease
• fenestration
• Fontan procedure
• hemodynamics
• single ventricle

This thesis addresses the topic of Fontan palliation in patients with functionally single ventricle physiology, a rare and complex congenital heart condition that requires a highly specialized surgical approach. In such patients, the cardiac anatomy does not allow for a biventricular repair, thus necessitating a series of palliative procedures culminating in the Fontan operation, which aims to separate systemic and pulmonary circulation in the absence of a functional right ventricle.
Over the decades, the Fontan technique has undergone numerous modifications, evolving from early atriopulmonary connections to current extracardiac conduit models, with or without fenestration. Fenestration consists of a small, intentional communication between the systemic venous return and the atrium or cardiac chamber, serving as a “pressure relief valve” to reduce immediate postoperative hemodynamic complications. However, its benefit remains a matter of debate, as fenestration may offer short-term advantages but also carries potential long-term drawbacks.
The thesis is structured into two main sections: a review of the literature and an original clinical investigation analyzing a cohort of patients who underwent Fontan surgery. The main objective is to evaluate the impact of fenestration on postoperative outcomes, both short- and long-term.
Literature Review - The first section provides a historical and conceptual overview of the Fontan procedure, from its initial implementation in the 1970s to the latest modifications involving the use of synthetic extracardiac conduits. Special focus is placed on the rationale and evolution of fenestration, initially introduced as a strategy to reduce early complications such as low cardiac output syndrome, prolonged pleural effusion, and early Fontan failure.
Recent studies present conflicting evidence: while fenestration appears to reduce early postoperative risk in selected patients, it may also increase the incidence of thromboembolic events, chronic desaturation, and the need for transcatheter closure. Therefore, the literature supports careful, patient-specific evaluation when deciding whether or not to use fenestration.
Experimental Study - The second part presents a retrospective study conducted on a single-institution cohort of patients who underwent Fontan palliation over the last decade. Patients were divided into two groups: those with fenestration and those without. Clinical data were collected and analyzed across preoperative, perioperative, and postoperative periods, with particular attention to short- and long-term outcomes.
Preoperative parameters included oxygen saturation, Nakata index (a measure of pulmonary artery size), and ventricular function. The analysis revealed that patients with fenestration had significantly lower preoperative oxygen saturation and lower Nakata indices, suggesting that fenestration was more often selected for hemodynamically fragile patients at higher risk.
During the early postoperative period, variables such as duration of mechanical ventilation, pleural effusion, inotropic support, incidence of low cardiac output syndrome, and major adverse events were recorded. Notably, a higher incidence of low cardiac output syndrome was observed in fenestrated patients, which may reflect the higher baseline risk of this group despite the fenestration. Nevertheless, no significant differences were found in the duration of ICU or overall hospital stay between the two groups. Similarly, the duration of pleural drainage and the prevalence of postoperative complications (excluding low cardiac output) were comparable.
In long-term follow-up, one patient underwent percutaneous closure of the fenestration, while four experienced spontaneous closure. Follow-up assessments showed a slightly lower average oxygen saturation of 95.6% (range: 80–100) in patients who had undergone fenestration, but this difference was not statistically significant. No differences were found between the fenestrated and non-fenestrated groups in terms of survival, need for re-intervention, or other major complications. These findings align with international literature, suggesting that while fenestration may offer early benefits, its long-term impact appears to be neutral in most cases.
Conclusions - This thesis supports the concept that the decision to fenestrate should be individualized based on each patient’s hemodynamic profile, pulmonary artery anatomy, and surgical risk factors. Fenestration appears to be beneficial for selected high-risk patients in the immediate postoperative period.
This study contributes to the ongoing international discussion on the role of fenestration in the Fontan strategy and encourages further multicenter, prospective studies with long-term follow-up to establish standardized protocols and optimize outcomes for patients with single-ventricle physiology.