Minimally invasive surgery for aortic valve replacement has become first choice approach in many centres, with excellent results, in terms of postoperative pain and reduction of hospitalization, ventilation times, occurrence of renal failure, and need for blood transfusion.1–5 A recently published meta-analysis5 confirmed the previously mentioned advantages, although it reported a longer duration of aortic cross-clamping and cardiopulmonary bypass times. Nevertheless, the potential benefit of minimally invasive surgery for aortic valve disease associated with ascending aorta dilatation remains questionable.
This study is a single-center retrospective analysis of a small cohort of 53 selected patients affected by aortic valve disease associated with ascending aorta dilatation treated with modified Bentall–De Bono operations performed through a minimally invasive approach via an upper hemisternotomy. Incidence of mortality and postoperative morbidity in terms of renal failure, ventilation time, sepsis, re-exploration for bleeding, and cerebrovascular major accidents have been analyzed.
PATIENTS AND METHODS
The study was approved by the local ethics committee, and each patient signed an informed consent for treatment and use of personal data.
Between January 2010 and the end of November 2015, a total of 238 adult patients underwent Bentall–De Bono operation operations at our institution. Among them, 53 patients (22.1%) were treated with a minimally invasive approach via an upper hemisternotomy. The choice of the surgical approach was at the discretion of the attending surgeon.
Exclusion criteria for the minimally invasive approach were the following: aortic valve active endocarditis, reoperation, acute type A dissection, and concomitant cardiac procedures.
Demographic, intraoperative, and outcome data of all 53 patients were collected and analyzed (Table 1). The population included 44 males (83 %) with a median age of 63 years (interquartile range, 51–73).
Indication for root surgery included chronic aneurysm due to calcified degenerative disease in 24 patients (45.3%), annuloaortic ectasia in 27 patients (50.9%), and infective chronic endocarditis in the remaining 2 patients (3.8%). The native aortic valve pathophysiology consisted of stenosis in 13 patients, regurgitation in 29 patients, and mixed lesion in 11 patients; a bicuspid valve was present in 26 cases (49%). Operative risk was evaluated according to the logistic European System for Cardiac Operative Risk Evaluation (logistic EuroSCORE).
General anesthesia was performed according to the standard protocol. External defibrillator pads were placed and a transesophageal echocardiographic probe was positioned in every patient.
A midline skin incision approximately 6 cm in length was performed from the manubriosternal junction to the third intercostal space. Stryker sternal saw was used. After pericardiotomy, the patients were heparinized and a central direct cannulation was used in almost all patients except for one. The aortic cannula (EOPA arterial cannula; Medtronic, Inc, Minneapolis, MN USA) was positioned in the proximal portion of aortic arch. For the venous drainage, a three-stage MC2X cannula (Medtronic, Inc) was placed in the right atrium—inferior vena cava. The left ventricle vent was placed through the right upper pulmonary vein. A 2-L/min continuous carbon dioxide insufflation was used during the entire operation.
The aorta was cross-clamped through a 1-cm skin separate incision made above the origin of the innominate vein using a Chitwood clamp (Scanlan International, Inc, St Paul, MN USA) (Fig. 1). Hypothermic 4°C blood cardioplegia (St Thomas with procaine) was antegradely infused into the aortic root to stop the heart and in case of aortic regurgitation directly into the coronary ostia.
The aneurismatic portion of the ascending aorta was excised. In only four patients, the Carbomedics Carbo-Seal (Sorin Biomedica, Saluggia, Italy) mechanical conduit was used. For the remaining population, a biological Bentall was preferred performed using two different surgical techniques: firstly, we used for three patients the “double sewing ring technique” previously described.6 Briefly, the Valsalva graft (Vascutek Gelweave Valsalva graft; Vascutek-Terumo, Glasgow, Scotland, United Kingdom) was everted and the biological prosthesis sutured on the free margin of the everted tube with 4-0 polypropylene running sutures. Afterwards, the valved graft returned to its original position and the proximal anastomosis performed with three 3–0 polypropylene running sutures between the aortic annulus and the free edge of the Valsalva prosthesis. Lately, we prefer another technique consisting in the concomitant, single-step suture between the bioprosthesis (Mitroflow pericardial valves; Sorin Srl, Milano, Italy), the Valsalva graft (Vascutek Gelweave Valsalva graft, or MAQUET CARDIOROOT; MAQUET, Rastatt, Germany, bulged graft), and the aortic annulus using running suture with tree 2/0 polypropilene or single 2/0 Tycron suture with pledget to reinforce a thin annulus depending on surgeon preference and on the annulus frailty. First, the left and then the right coronary ostia were sutured with 5–0 polypropilene and the distal anastomosis performed routinely with 4/0 suture (Fig. 1).
Ventricular temporary pacing wires were placed on the right ventricle. Aorta was then declamped and the patient weaned from cardiopulmonary bypass. Intraoperative transesophageal echocardiography was performed to asses the correct valve function in all patients.
Cannulae were removed and protamine was administered at 1:1 ratio to heparin. Chest drain tubes were placed from subxiphoid access. Sternum was closed with steel wires and subcutaneous sutures used for wound closure.
Continuous variables were expressed as mean ± standard deviation (SD) and as median and interquartile range (IQR). Minimum and maximum values were also presented. Categorical variables were expressed as frequencies and percentages.
Differences between full sternotomy group and minimally invasive group were evaluated using two-sided, nonparametric Wilcoxon rank sum test for continuous variables and χ2 or Fisher exact test for categorical variables. The curves of the overall survival after discharge were estimated using the Kaplan-Meier product-limit estimator and compared using the log-rank test.
A P value of less than 0.05 was considered statistically significant for all statistical tests.
Early outcomes and complications are reported in Table 2.
A biological Bentall using a pericardial Mitroflow bioprosthesis implanted in a Valsalva graft was performed in 49 patents. The remaining four patients were treated with a traditional mechanical conduit. All patients were discharged alive. Median (IQR) cardiopulmonary bypass time and median cross-clamp time were respectively 84 (75–103) and 73 (64–89) minutes. The median intensive care unit and hospital stay were 1.9 and 8 days.
During the same period, we performed 185 classical Bentall–De Bono operation using standard full sternotomy. We compare the two populations, but important differences in preoperative characteristics were present as shown in Table 1. For this reason, we decide to exclude the patients who underwent emergency surgery for aortic dissection, reoperations, and associated aortic arch replacement obtaining in the end two similar populations (Table 2).
The two groups showed similar results in terms of postoperative outcomes with a slightly superiority of minimally invasive group mainly regarding operative times, incidence of atrial fibrillation, and postoperative ventilation times (Tables 3, 4).
Up to now, few articles have been published concerning replacement of the aortic valve and/or aortic root/ascending aorta through minimally invasive approach6–16; mostly, they reported a single high-volume center activity for a long period including heterogeneous surgery of the aorta.
Recently, Deschka et al7 reported the experience and outcomes of ministernotomy in 50 patients operated with aortoplasty or isolated replacement of ascending aorta or ascending aorta associated with aortic valve replacement/reconstruction, with an excellent survival rate (100%). Totaro et al9 published the largest series (67 Bentall) of complex cardiac procedures using a minimally invasive approach showing good results in a very heterogeneous patient population using different surgical techniques. Tabata et al11 compared two patients populations, the minimally invasive and the full sternotomy group, and no differences in terms of mortality and morbidity were revealed. In an interesting review, Perrotta and Lentini8 underlined as data in the literature are still too limited to demonstrate an effective beneficial effect of minimally invasive techniques. In conclusion, our experience shows that upper “J” ministernotomy guarantees an optimal surgical exposure of the aortic root, optimal to perform Bentall–De Bono operations using total central cannulation and with operative times comparable with those reported for the traditional approach. In our series of minimally invasive approach, operative times are even shorter, but it is mainly due to the peculiar surgeon's experience. This is possible thanks to a standardized technique, for which an appropriate training is essential and is starting from the traditional full sternotomy to reach a minimally invasive approach. The surgeon's experience could be an exclusion criteria for the minimally invasive approach in addition to aortic valve active endocarditis, reoperation, acute type A dissection, and concomitant cardiac procedures.
In addition to the indisputable better esthetical result, the small incision has a very low risk of sternal instability and infection.
The high rate of biological conduit could be controversial if compared with the young age of patient population; nowadays, the role of patient in the decision making is not negligible and more and more often young patients prefer biological prosthesis instead of mechanical one for many different reasons, despite the risk of reoperation.
Our results confirm the literature data1,5,17 showing that this technique is safe for aortic root surgery with a slightly superiority compared with the standard full sternotomy approach in terms of operative times, incidence of atrial fibrillation, postoperative ventilation times, and with a superior cosmetic result.
There are several limitations in our study. Firstly, it is a single-center retrospective, nonrandomization study.
The number of patients is relatively small, and this limited the statistical power of the analysis. In addition, there is no control group, and the decision of the surgical approach depends on surgeon's experience and preference.
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This retrospective case series from Mikus et al described their experience with a mini-Bentall procedure in 53 patients. The operation was performed through a 6-cm incision, and the sternum was divided with a J-incision from the sternal notch down into the third right intercostal space. There was no mortality in this small series, and they had similar outcomes with this approach when compared with a selected group of full sternotomy patients undergoing surgery during the same period.
This series demonstrated the feasibility of a minimally invasive Bentall procedure in selected patients. However, there are significant limitations to their report, which prevent the reader from drawing any firm conclusions. The study population was very small, and this highly limits the statistical power of their analysis to determine the real advantages and disadvantages of this technique. Moreover, the retrospective nature of the analysis and the lack of a control group raise the question of selection bias, making it even more difficult to determine the clinical utility of this operation.With these shortcomings in mind, the authors are to be congratulated for their excellent results with the mini-Bentall procedure.
Keywords:©2017 by the International Society for Minimally Invasive Cardiothoracic Surgery
Minimally invasive surgery; Bentall operation; Valve sparing technique; Upper J sternotomy; Ministernotomy