3D thinking for mini-AVR

A computed tomography-based planning tool for predicting difficulty of minimally invasive aortic valve replacement

OBJECTIVES

Minimally invasive aortic valve replacement has proven its value over the last decade by its significant advancement and reduction in mortality, morbidity and admission time. However, minimally invasive aortic valve replacement is associated with some on-site difficulties such as limited aortic annulus exposure. Currently, computed tomography scans are used to evaluate the anatomical relationship among the intercostal spaces, ascending aorta and aortic valve prior to surgery. We hypothesized that quantitative measurements of access distance and access angle are associated with outcome and access difficulty.

METHODS

We introduce a novel minimally invasive aortic valve replacement planning prototype that allows automatic measurements of access angle, access distance and aortic annulus dimensions. The prototype visualizes these measurements on the chest cage as ISO contours. The association of these measures with outcome parameters such as extracorporeal circulation time, aortic cross-clamping time and access difficulty score was assessed. We included 14 patients who received a new valve by ministernotomy.

RESULTS

The mean access angle was 40.3 ± 5.1°. It was strongly associated with aortic cross-clamping time (Pearson correlation coefficient = 0.60, P = 0.02) and access difficulty score (Spearman's rank correlation coefficient = 0.57, P = 0.03). Access angles were significantly different between easy and difficult access groups (P = 0.03). There was no significant association between access distance and outcome parameters.

CONCLUSIONS

Access angle is strongly associated with procedure complexity. The automated presentation of this measure suggests added value of the prototype in clinical practice.

Minimally invasive aortic valve replacement: Comparison of long-term outcomes

Background

Minimally invasive aortic valve replacement tends to be performed in specialist centers. Little data exists with regard to long-term outcomes of the upper hemi-sternotomy technique. We sought to evaluate the short- and long-term outcomes of this procedure in our institution.

Methods

Data were collected from our cardiac surgical database. We compared the outcomes of all patients who underwent minimally invasive aortic valve replacement with all who underwent conventional aortic valve replacement between July 1999 and December 2013. Propensity-matching analysis was performed to evaluate hospital outcomes.

Results

There were 125 patients who underwent minimally invasive aortic valve replacement and 1446 who had conventional surgery. After propensity score matching, there were no differences in postoperative mortality or complications between the 2 groups. The only significant differences were longer bypass (62.69 ± 10.12 vs. 68.94 ± 14.79 min, p = 0.002) and crossclamp times (45.48 ± 8.08 vs. 52.30 ± 16.29 min, p < 0.001) in conventional surgery. Long-term survival after minimally invasive aortic valve replacement at 2, 6, and 10 years was 88% ± 3.0%, 79% ± 4.0%, and 66% ± 6.0%, respectively. Predictors of long-term survival were age, peripheral vascular disease, and low ejection fraction ( p < 0.005).

Conclusion

Minimally invasive aortic valve replacement has similar hospital outcomes compared to conventional aortic valve replacement. The operation is quicker and does not confer any significant increase in complications or length of hospital stay. The long-term outcomes are favorable and justify its continued use by specialist surgeons in the United Kingdom.