Primary goal of surgery for AADA, a life-threatening event, remains to save the patient’s life. Today, surgical approaches for AADA repair range from simple SCR to complete thoracic aortic replacement with aortic valve reconstruction. Surgery in AADA should not only treat acute complications but should also prevent or at least minimize the risk for early and late complications after aortic dissection (e.g. downstream aneurysm formation) [11]. This approach demands a repair of all dissected parts of the aorta, in most cases including the aortic arch and descending aorta. However, extensive surgical procedures for AADA, such as aortic root replacement, TAR or hybrid procedures for concomitant dissection of the downstream aorta, remain controversial [3, 4, 6, 12]. Furthermore, although the surgical outcomes of AADA have been improved significantly during the last decades, standardization in repair techniques is still lacking [3,4,5]. Moreover, the surgical strategy usually still depends on a surgeon’s preference and experience.
In the first years of the study period, femoral artery cannulation was the widest used cannulation technique. However, direct aortic cannulation was later on preferred by several surgeons who joined the team in the 2000 years. Direct aortic cannulation (preferably with use of Seldinger technique) can be performed in experienced hands with good results, as proofed by several publications [13]. However, during the last years of the study period and with growing evidence that axillary cannulation is superior to direct aortic cannulation, axillary cannulation became standard cannulation technique [14].
SCR is technically the simplest approach, the fastest surgical strategy and the most common used method for AADA repair. Many studies reported lower perioperative mortality after limited surgical strategy (such as simple SCR technique) but on the other hand higher rates of late complications with need for re-interventions [7, 10, 15, 16]. On the contrary, more extended surgery, such as aortic root replacement and TAR with or without stenting of the descending aorta (frozen elephant trunk technique), has proved to reduce late dissection complications and the need for re-interventions [11, 17, 18]. Contradictory data in literature is the reason why the best surgical approach still remains uncertain.
Although patients were younger in the concomitant aortic root and arch replacement group (COMP+TAR), intraoperative mortality was observed higher. This finding may be explained by a combination of longer operation and circulatory arrest times. Early mortality comparisons, however, were statistically insignificant.
Our study results stand in contrast to several previous reports indicating that favorable outcome is reduced if aortic arch surgery was undertaken [10, 19,20,21,22]. This report revealed comparable long-term survival rates for SCR and operations with extended aortic arch repair. Our results are supported by GERAADA (German Registry for Acute Aortic Dissection Type A) results and many other recent studies [4, 18, 23]. Therefore, we suppose that more extensive aortic arch surgery does not cause worse overall outcome in principle.
Based on GERAADA registry data, containing 2137 surgically treated patients with AADA between year 2006 and 2010, Conzelmann et al. reported an early mortality of 16.9% in patients with AADA [4]. Within our cohort the overall early mortality was relatively high (21%). The long retrospective study period in our cohort (back to year 1988) may explain our overall inferior results. During more recent time periods, our results are comparable to the reported mortality in GERAADA. Besides new and more sophisticated surgical strategies, the general improvements in perioperative treatment over the last decades may have impacted the overall outcome for patients with AADA. Our relatively poor early survival rate is supported by the findings of similar reports with comparable long retrospective study periods [5, 6, 24].
As it has been reported previously, we did not detect superiority of a specific surgical technique concerning long-term survival [4, 23]. However, our patients from the AVS group showed favorable early and long-term outcomes but with only a trend towards survival improvement. Many factors may explain these good results of AVS in patients with AADA: First, surgeons operating AVS usually have more surgical experience. Second, the majority of these AVS operations had been performed more recently (after year 2006). Third, AVS technique is usually not considered in high-risk patients and advanced aortic disease. On the other hand, we have to underline, that our results also indicate an increased risk for postoperative bleeding with need for re-thoracotomy after AVS (29%). Interestingly this finding seems not to have any impact on short- and long-term survival in our cohort. Even if the scientific evidence is still weak, in our opinion AVS should always, as long as technically feasible, be the first choice for experienced surgeons if the aortic root is affected. Especially young patients (with or without Marfan syndrome) benefit from AVS, because a lifetime oral anticoagulation is not required.
Need for re-operation is an important factor impacting the quality of life of patients with AADA. Within our cohort younger age and Marfan syndrome were identified as risk factors for redo operation. The estimated 5-year survival within our cohort was 78% after redo operation and is comparable to the results of recent publications [25, 26]. The question for the best AVS technique in AADA, Yacoub or David technique, has not been answered yet. Theoretically, and based on our experience the David procedure requires longer operation times. A significant difference in short and long-term survival was not observed. But in our relatively small cohort of AADA patients receiving AVS (n = 35), the observed need for re-aortic root operations was less frequent after David technique compared to Yacoub. Because David is the more recent and advanced technique and on the other hand Yacoub technique has been performed at earlier study period at our institution, time is about to tell if David operation is really the favorable AVS approach. In the literature, there is a trend towards better valve longevity for patients after the David procedure compared to the Yacoub technique [27, 28].
Similar to the results of the registry data of GERAADA, our findings indicate the predictive value of neurological complications, circulatory arrest, bypass and operation time as important risk factors for early mortality [(4)]. Beyond that and as previously reported by Goda et al., freedom from cardiac circulatory arrest and preoperative cerebral malperfusion are valid predictors for long-term survival [23]. The duration of circulatory arrest seems to have a strong impact on general outcomes. As mentioned, patients with AADA and affected aortic arch may benefit from extended aortic arch surgery in circulatory arrest but in general longer circulatory arrest time seems to limit the overall outcome. The upcoming results of the big registry data such as GERAADA will have to tell us, how this small path between extended aortic arch surgery and limitation of circulatory arrest time has to look like finally.
Limitations
Our single-center study has an exploratory character and based exclusively on retrospective analysis of surgical strategies used in AADA repair. An important limitation is the long study period over 25 years that included the change and development of surgical techniques during the study period. Moreover, our patient cohort is inhomogeneous due to the natural individual characteristic of AADA. Furthermore, surgical technique was chosen individually according to clinical presentation and, more dominantly, according to surgeon’s preference. The influence impact of the surgeon per se was not measured.