Minimally invasive cardiac surgery (MICS) is becoming increasingly popular for redo mitral valve repair because it reduces trauma, decreases recovery time, and minimizes complications compared to traditional sternotomy. However, performing MICS in patients with severe atherosclerotic and artheromic aortic disease presents unique challenges, particularly in maintaining safe and effective perfusion during cardiopulmonary bypass (CPB). Standard CPB techniques, which often rely on femoral artery (FA) cannulation, can pose significant risks in these patients due to the possibility of retrograde embolization, which may lead to postoperative strokes or other neurological complications.
This study evaluates a novel approach to perfusion during MICS in high-risk patients, employing both antegrade and retrograde circulation to optimize blood flow and reduce the likelihood of cerebral infarction. By using a combination of ascending aortic (Asc Ao) and femoral artery perfusion, this strategy ensures better perfusion control and minimizes the dangers associated with embolic events. The study also examines the dynamics of the “mixing zone,” the area in the aorta where antegrade and retrograde blood flows meet. A case report demonstrates how this approach can be successfully applied in a patient undergoing redo mitral valve plasty (MVP) with severe aortic disease.
Redo mitral valve procedures are inherently more complex than first-time surgeries due to factors such as adhesions, scar tissue, and altered anatomical structures from prior interventions. Additionally, in patients with extensive aortic calcification and thrombosis, perfusion management must be meticulously planned to prevent complications. Traditional perfusion strategies often rely on FA cannulation alone, which can increase the risk of embolism, as retrograde perfusion may dislodge plaques or thrombi, sending them toward the brain.
In this case study, a patient with a history of coronary artery bypass grafting (CABG) and severe mitral regurgitation underwent a fully endoscopic redo MVP. Preoperative imaging revealed significant aortic calcification and thrombotic burden, making traditional perfusion methods risky. Given the patient’s increased risk of cerebral infarction, a strategic perfusion plan was developed using a combination of Asc Ao and FA cannulation to balance antegrade and retrograde blood flow. CPB was established with a right femoral vein cannula (23/25Fr), a femoral artery cannula (18Fr), and an ascending aorta cannula (14Fr). Mean arterial blood pressure (mABP) was carefully maintained above 60 mmHg throughout the procedure. To manage aortic insufficiency and ensure a clear surgical field, systemic hyperkalemia-induced cardiac arrest was employed, along with controlled circulatory arrest.
A key aspect of this study was the evaluation of the mixing zone during CPB. The mixing zone is the region where opposing blood flows meet within the aorta, and its location and characteristics can significantly impact hemodynamic stability and cerebral perfusion. If the mixing zone is positioned too high in the aortic arch, there is a greater risk of disturbed cerebral perfusion and embolization. To analyze the effects of different perfusion strategies, the study employed an arteriovenous circulation model to simulate blood flow dynamics under various conditions.
Several perfusion configurations were tested to determine the safest and most effective strategy. When using a 14Fr Asc Ao cannula with an 18Fr FA cannula, the mixing zone was observed primarily in the descending aorta, minimizing cerebral risks. With a 14Fr Asc Ao cannula and a 16Fr FA cannula, the mixing zone remained stable in the descending aorta across different flow rates, further supporting its safety. However, when a 14Fr Asc Ao cannula was combined with a 20Fr FA cannula, the mixing zone shifted closer to the aortic arch, increasing the potential risk of embolic events. Based on these findings, the study suggests that when performing combined perfusion via the Asc Ao and FA, selecting an Asc Ao cannula that is one size smaller than the FA cannula optimizes perfusion safety and reduces the risk of complications.
Postoperatively, the patient recovered without any neurological complications. CPB lasted 394 minutes, with circulatory arrest maintained for 25 minutes. The patient’s hospital stay was 16 days, and no major complications were observed. The successful outcome of this case supports the effectiveness of combined antegrade and retrograde perfusion in reducing postoperative neurological complications in patients with severe aortic disease.
The findings of this study have important clinical implications for perfusion strategies in MICS, particularly for high-risk patients with extensive aortic pathology. The use of a mixing zone model provides valuable insights into how blood flow dynamics can be optimized to improve patient outcomes. However, while this study demonstrates the feasibility and benefits of this approach, further research is needed to refine perfusion techniques. Real-time intraoperative flow monitoring and computational fluid dynamics modeling could help further optimize perfusion strategies based on patient-specific anatomy and pathology.
Despite the promising results, some limitations must be acknowledged. The study focuses on a single case, and while the simulation model provides useful insights, it does not account for all physiological variables present in a live surgical setting. The impact of ventral branches such as the celiac artery, renal artery, and superior mesenteric artery on mixing zone dynamics was not included in the model, meaning that real-world conditions may slightly differ from the simulations. Future studies involving larger patient cohorts and more advanced simulation techniques will be essential in further validating these findings.
The importance of perfusion strategy in minimally invasive cardiac surgery cannot be overstated, especially in patients with significant aortic disease. This study highlights the potential for improving CPB outcomes by carefully selecting cannulation sites and sizes to optimize blood flow. The combined antegrade and retrograde perfusion approach provides a promising alternative to traditional FA cannulation alone, reducing the risks of embolic events and ensuring safer cerebral perfusion.
As minimally invasive techniques continue to evolve, optimizing perfusion strategies will be critical in enhancing patient outcomes and expanding the applicability of these procedures to more complex cases. This study provides an important step in understanding how blood flow dynamics can be manipulated to improve safety in high-risk patients. By leveraging perfusion modeling and simulation, cardiac surgeons can make more informed decisions, ultimately leading to better surgical outcomes and reduced postoperative complications.
Study Ranking = 3 (High-Quality Case Report with Simulation Study) This study provides valuable insights using a combination of clinical case evaluation and perfusion modeling. However, it remains a single case report with simulation-based findings rather than a large-scale randomized trial, which would be needed for the highest level of evidence.
