Objectives

Although CO₂ insufflation play an established role in open-heart surgery, its optimal application in minimally invasive cardiac procedures remains unclear. This study systematically compared continuous versus single CO₂ insufflation protocols during minimally invasive modified morrow procedures, and assessed the influence of left heart venting modality on microbubble clearance efficacy.

Methods

This retrospective cohort study included 351 patients undergoing minimally invasive modified morrow procedures (2023–2024). Participants were stratified into two groups: Continuous Insufflation Group (CIG, n = 228; 5 L/min CO₂ throughout cardiopulmonary bypass [CPB]) and Single Insufflation Group (SIG, n = 123; 5 L/min CO₂ 5-min pre-aortotomy closure to 5-min post-unclamping). Microbubble dynamics were quantitatively classified into four grades (0-III) using standardized intraoperative transesophageal echocardiography. Multivariate logistic regression was used to identify predictors of microbubble formation and clinical outcomes.

Results

The CIG exhibited a statistically significant reduction in overall microbubble incidence compared to SIG (13.60% vs. 36.59%, p < 0.05), particularly in attenuating Grade I-II microbubbles (p < 0.05). Multivariate analysis identified CO₂ insufflation strategy (odds ratio [OR] = 3.694, p = 0.005), left heart venting modality (OR = 32.527, p < 0.001), and CPB time (OR = 1.017, p = 0.017) as independent predictors. Importantly, the combination of continuous insufflation with left ventricular venting was associated with a 93.3% reduction in Grade I microbubbles (OR = 0.067, p = 0.001). Clinically, the CIG exhibited a lower incidence of perioperative arrhythmias (24.12% vs. 36.59%, p = 0.009), despite slightly longer hospitalization (9.80 ± 4.42d vs. 8.88 ± 3.26d, p < 0.05). Neurological outcomes (4.82% vs. 3.25%, p = 0.483) and ICU stay duration (1.59 ± 1.69d vs. 1.74 ± 2.14d, p = 0.215) were comparable between groups.

Conclusion

In the context of the minimally invasive modified morrow procedure, continuous CO₂ insufflation significantly reduces microbubble formation and perioperative arrhythmias. Left ventricular venting modality is a key determinant of de-airing efficacy. Protocol optimization should prioritize continuous CO₂ insufflation in combination with left ventricular venting systems to enhance procedural safety.