Surgical procedures of the ascending aorta with or without total arch replacement and aortic root reconstruction have traditionally been performed via an FMS approach to ensure a good exposure. Recent advances in MIS techniques in combination with different partial sternotomy approaches have been employed as an alternative to FMS 12,18–20,21, being used to conduct isolated heart valve disease, Bentall procedure, hemi-arch replacement, and ascending aorta repair. These less invasive approaches have been linked to superior cosmetic and postoperative outcomes, including an overall reduction in surgical trauma, ventilator use, ICU stay duration, transfusion requirements, respiratory failure, and sternal stability as compared to FMS 18,22,23.
Although the Bentall technique and valve-paring aortic root surgery are complex procedures which necessitate a good overview, the value of PUS as an alternative access strategy for these complex procedures has been a topic of recent interest. 9–11 Hillebrand et al. 2 evaluated outcomes for 33 patients undergoing aortic root replacement with the Bentall procedure through a J-shaped PUS access and thereby confirmed the safety of PUS when conducting complex aortic surgery. Wachter et al. 24 also demonstrated the safety of valve-sparing aortic root replacement procedures with the David procedure performed via PUS.
The degree of obesity is correlated with increased certain adverse outcomes including renal failure, sternal and wound infections, hospitalization duration, and prolonged mechanical ventilation25–28. To determine whether the benefits of PUS were reduced due to obesity when undergoing aortic surgery, we herein compared PUS and FMS outcomes for obese and non-obese patients and explored the answer. This study is the most detailed analysis of this topic to date so far as we are aware.
Comorbidities, operative duration, and major complication rates
In our study, we observed comparable preoperative risk profiles and operative duration for both obese and non-obese patients when comparing the PUS and FMS groups. Although PUS was associated with a longer cross-clamp duration, we do not believe that this difference, on the scale of minutes of ischemic time, is likely to be clinically relevant.
Rates of mortality and major complications were comparable among PUS and FMS groups irrespective of BMI, indicating that obese patients are good candidates for PUS treatment.
Obesity has been tied to the prolongation of ventilation and increase hypoxemia after acute aortic dissection (AAD) surgical procedures 29. MIS approaches better preserve the integrity of the chest wall and thus have the potential to decrease the length of postoperative ventilator use. While obese patients did exhibit prolonged ventilator use relative to non-obese patients when comparing the PUS patient cohorts, PUS treatment was nonetheless associated with reductions in ventilator use for both obese and non-obese patients as compared to FMS treatment. We additionally observed no significant differences in rates of pneumonia, reintubation, or tracheotomy in the PUS group for obese or non-obese patients, suggesting that limited surgical access does not result in unfavorable pulmonary outcomes even among obese patients.
Patients in the present study that underwent treatment via a PUS approach exhibited reduced transfusion requirements as compared to patients treated via an FMS approach irrespective of whether or not they were obese. These results are in line with those of Wu et al. 30 and Xie et al. 13,19,31,32. Previous evidence suggested that transfusions was associated with a negative impact on outcomes following cardiac surgery 33–36. Obese patients in the present study that underwent PUS procedures did not exhibit any differences in transfusion requirements as compared to non-obese patients, further supporting the fact that this procedure does not expose obese individuals to greater risk.
Length of stay
MIS approaches are associated with decreased length of hospitalization and duration of ICU stay 37. Consistently, we found that both obese and non-obese patients in PUS group exhibited shorter durations of hospitalization and ICU stay as compared to FMS group. These findings are also consistent with previous meta-analyses13,22,24,25. We did not observe any differences in the length of ICU or hospital stays for obese patients in this study relative to non-obese patients in the PUS cohort, indicating that this MIS approach is not associated with increased risk for obese individuals.
We did not observe any protective benefits with respect to the odds of postoperative sternum infection in PUS cohort, which may contradict subjective clinical expectations. This might because the pathogenesis of sternal infections is likely multifactorial, and as such the improved integrity of the sternum alone is not sufficient to reduce the risk of sternum infection. Notably, we did not observe increased risk of postoperative sternal infections among obese patients in PUS cohort in this study, suggesting that PUS does not expose obese patients to additional risk of sternal infection.
Postoperative pain levels
Our results suggest that the PUS approach was associated with better postoperative pain levels. While these results do not align with those of a pooled analysis performed by Lim et al. 32, they are consistent with a meta-analysis conducted by Brown et al. 18 Overall, relatively limited data are available pertaining to this operative outcome, potentially explaining these contradictory results. We additionally found that obese and non-obese patients in PUS cohort experienced comparable levels of postoperative pain.
The present study was a retrospective analysis which is subject to inherent bias. In addition, the study period was relatively long and changes in perioperative therapeutic regimens over this period may have impacted these findings. Propensity score matching could not be performed, given that the inclusion criteria for the PUS group shifted over the course of the study period from being at the discretion of the operating surgeon to the standard departmental approach.