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Interact CardioVasc Thorac Surg 2009;9:849-858. doi:10.1510/icvts.2009.206904 © 2009 European Association of Cardio-Thoracic Surgery
Ministernotomy approach for surgery of the aortic root and ascending aorta
a Department of Cardiothoracic Surgery, Sahlgrenska University Hospital, 413 45, Gothenburg, Sweden Received 30 March 2009; received in revised form 30 June 2009; accepted 15 July 2009
*Corresponding author. Tel.: +46737238120.
Different minimally invasive approaches have been proposed for cardiac surgery. Between those, the ministernotomy finds wide consensus for the treatment of the aortic disease, being both the upper reversed T and the upper J the mostly used type of incisions. The authors review the literature on the use of ministernotomy in the treatment of the ascending aorta and arch pathology. The scientific literature was reviewed by searching Medline, the Cochrane Library and the CINAHL database. A total of 1411 papers were found in Medline, 186 in the Cochrane database and 514 in CINAHL database; 50 papers were used to write the article; of which seven represent the most significant papers on the subject. The authors, journal, date and country of publication, patients group studied, relevant outcomes, and the results of these papers are tabulated. The ministernotomy is gaining consensus among surgeons. The indication to surgery, initially restricted only to selected elective patients, is now extended to more complex surgeries, including both the aortic root and aortic arch, redo-operations and, in minor cases, to emergency patients. Furthermore, the use of ministernotomy in redo aortic surgery with patent left internal mammary artery (LIMA) to left anterior descending (LAD) artery is a promising alternative. However, the use of this technique is still limited to few institutions and there are still a limited number of studies comparing this approach to full sternotomy in a prospective, randomized fashion. Even with those limitations, from the review of the literature, it seems that ministernotomy approach for aortic root and ascending aorta surgery is a feasible alternative, showing some advantages compared to full sternotomy. Those advantages include: reduced postoperative bleeding and pain, lower risk of mediastinitis, better aesthetic results, and faster respiratory function recovery. This is true not only for first time surgery, but also, and especially, for redo cases, where the limited exposure will reduce risks correlated to the surgical dissection of redo surgery. The ministernotomy approach for aortic root and ascending aorta surgery could in the future be more extensively used, offering greater benefits to cardiac surgical patients.
Key Words: Aneurysm; Aortic operation; Aortic root; Minimally invasive surgery
In cardiac surgery, minimally invasive approaches are used in order to reduce surgical trauma, while at the same time trying to provide a good field for operation. The standard incision in cardiac surgery is a median sternotomy, which has proven to be a versatile and reliable approach. However, other surgical approaches have been proposed with the aim to reduce surgical trauma and improve the postoperative course, hastening the return to normal activities. The main alternatives proposed are an upper hemisternotomy and a lower sternotomy [1, 2]. Both of these allow central cannulation for a cardiopulmonary bypass (CPB) using standard equipment and, if necessary, prompt conversion to a complete median sternotomy. The anatomical aspects of exposure provided by an upper hemisternotomy and a lower sternotomy have been studied by Reardon et al. [3]. Usually, the ministernotomy is performed through a vertical incision through the skin and sternum and completed by a transverse sternal incision. Different types of ministernotomy incisions have been proposed, such as an upper reversed T incision [4], a right side partial sternotomy [5], an upper J incision [6, 7], an S-shaped partial sternotomy [8], a right parasternal incision [9, 10], a lower half ministernotomy (T incision) [11], an L-shaped incision [12], a reversed Z-shaped sternotomy [13], an I-shaped ministernotomy [14] and a reversed C-shaped ministernotomy [15]. Holman and Willett reported in 1949 the first use of a partial sternotomy approach. They used a partial vertical sternotomy with transection of the sternum at the second intercostal space for pericardiectomy [16, 17]. The same approach was used to remove lesions localized in the anterior mediastinum, such as a substernal thyroid adenoma or for the exposure of the trachea and the upper thoracic oesophagus [18, 19]. A variety of operations may be performed through this approach, including aortic valve replacement [20], mitral valve replacement [21], coronary bypass grafting operation [22], ascending aorta aneurysm [23, 24], aortic root replacement with composite graft [25], combined cardiac operations [26] and cardiac re-operations [27, 28]. Ministernotomy is also used in patients with previous cardiac operations with the aim to avoid the dissection of ventricle adhesions, allowing the surgeon to expose only a limited required area. In this article, through a literature review, we analyze the use of the ministernotomy in the treatment of aortic root and ascending aorta diseases.
2.1. Literature search A computerized search was conducted on the Medline database, on the Cochrane Library, and on the CINAHL database. Articles were defined to be relevant for this review if their subject was related to the issue at hand. The selected articles were reviewed by the authors and judged on their relevant contribution to the subject of this study. The scientific literature was reviewed primarily by searching Medline from 1950 to 2009 using an OVID interface. (exp Surgical Procedures, Minimally Invasive/ OR minimally invasive surgery.mp OR ministernotomy.mp OR minimally invasive.mp) AND (exp Aorta, Thoracic/ OR aorta.mp). This search was performed in the database of the Cochrane Library. [(Surgical Procedures, Minimally Invasive OR minimally invasive surgery OR ministernotomy OR minimally invasive) AND (Aorta, Thoracic OR aorta)]. The same research was performed in the CINAHL database. (TI surgical procedures, minimally invasive OR TI minimally invasive surgery OR TI ministernotomy OR TI minimally invasive AND TI aorta, thoracic OR TI aorta). The ‘related article’ function was used to broaden the search and all abstracts, studies, and citations were reviewed. Furthermore, all references listed were hand-searched for other relevant articles as well as utilising a citation tracker in order to identify any relevant literature. Two independent authors reviewed these results and then the final accepted papers were agreed by consensus between the two. A total of 1411 papers were found in Medline, 186 in the Cochrane database and 514 in CINAHL database. Among these, 50 papers were included in this review. Furthermore, the results of the seven most relevant papers are presented in Table 1.
There are several types of minimally invasive approaches for cardiac surgery reported in the literature. Among them, the upper J and the T inverted ministernotomy for treatment of the aortic root and ascending aorta are the most commonly used (Fig. 1). However, the ministernotomy is performed by a few surgeons and in selected centres. In fact, there are not many articles published in this specific field. In these papers, the authors usually refer to the total activity of the centre over a long period of time and often include different types of surgery on the aorta. Furthermore, almost no authors compare the results of a minimally invasive approach to results with a standard sternotomy. For these reasons, the results analysis leaves many unanswered questions.
3.1. Surgical technique Different types of ministernotomy incisions have been suggested for cardiac surgery. In order to expose the anatomical structure of the superior mediastinum, the upper T ministernotomy and the upper J shape ministernotomy are apparently the most widely employed incisions [29–31]. The upper reversed T ministernotomy is performed starting from the sternal notch and extended caudally to the level of the third or fourth intercostal space and then converted to an inverted ‘T’ shape. The inverted ‘T’ incision can be carried out in one of these two intercostal spaces, depending on the estimated position of the aortic valve, documented by trans-esophageal echocardiography (TEE). The proximity of the upper part of the aortic root to the sternum and the median position of the aorta do not require spreading the two hemisternum more than 5 cm in order to perform the procedure. Therefore, there is no need for mobilization or ligation of the internal mammary arteries. The spreading of the two hemisternum more than 5 cm can instead require the sacrifice of one or both of the internal mammary arteries. With the J shaped incision, the sternum is incised from the sternal notch vertically to the right third or fourth intercostal space. Usually, there is no need to ligate the mammary artery. Normally, both of these types of incisions give a good exposure, allowing central venous and arterial cannulation. Central arterial cannulation can be prepared through the ascending aorta or the aortic arch, while the peripheral cannulation can be established through the femoral or the axillary artery. Venous cannulation is established through the right atrium or the superior vena cava. Alternatively, if control of the right atrium through the ministernotomy is difficult, venous cannulation can be achieved through the left innominate vein [29, 32], or through the femoral vein. Concerning myocardial protection, both crystalloid and haematic (cold or warm) cardioplegia may be used during ministernotomy [25, 30]. Myocardial protection can be obtained delivering antegrade cardioplegia through the aortic root or directly through the coronary orifices after aortotomy. Retrograde cardioplegia can be delivered through a coronary sinus cannula placed through the right atrial appendage or it can be delivered via a Heartport trans-jugular coronary sinus catheter (Heartport®, Redwood City, CA) [29, 33]. In both cases, the cannulation of the coronary sinus can be made easier using TEE guidance. Furthermore, topical cooling by pouring ice on the heart can be easily achieved. If circulatory arrest is required, hypothermia is used according to the surgeon's preference. Surgery is usually completed according to the same technique used with complete sternotomy. The left ventricle may be vented through the superior right pulmonary vein or directly through the aortic valve, as preferred. Alternatively, the vent may be placed in the pulmonary trunk. During the de-airing procedure, in order to mobilize residual air bubbles, the left ventricle may be gently pressed with a paddle and trans-esophageal ultrasound can be used to help evaluate the efficacy of the procedure. Beyond the use of mechanical manoeuvres, the use of preoperative CO2 [34] in the surgical field may reduce the risk of an air embolism. 3.2. Advantages and disadvantages of ministernotomy Partial sternotomy compared with full sternotomy, seems to give less postoperative pain [25, 35]. Other potential advantages include reduced blood loss and transfusion requirements [29, 35], and a shorter wound with reduced risk of postoperative soft tissue infections and mediastinitis [35]. This may be related to the shorter incision and to the reduced tension on the soft tissues as well as to reduced blood loss. A shorter skin incision also gives a better aesthetic scar appearance [30]. After ministernotomy, patients have a faster return to normal life and less need for post-hospital rehabilitation [9]. A minimally invasive approach, exposing only a limited portion of the heart, is considered to produce fewer adhesions on the heart than a full sternotomy, which is useful in case of a second heart surgery [27, 33]. In fact, in those cases using the ministernotomy approach, the right ventricular wall is not exposed, reducing, therefore, the risks correlated with tissue re-dissection, and blood loss. Ministernotomy also improves respiratory function recovery and allows earlier extubation [35] and hospital discharge [35, 36]. Nevertheless, if required, it is possible to convert the ministernotomy to a full sternotomy [37].The main disadvantage of partial sternotomy may be the need under certain circumstances to sacrifice one or both of the internal mammary arteries. Usually, this is not necessary, unless there is the need to split the sternum more than usual. There may rarely be injury to one or more intercostal neurovascular bundles, or instability of the anterior chest wall. Of course, a small incision with limited exposure would make it more difficult to deal with intraoperative complications. For this reason, the use and the success of this technique are related to the technical experience of the surgeon [31, 36]. Another disadvantage is the need to rewire three separated segments of the sternum, in contrast with only two segments with the full sternotomy. Nevertheless, despite the claimed advantages of the ministernotomy approach compared with the complete sternotomy, not all authors agree on the benefit of this approach. Aris et al. [38] report that partial sternotomy offers a cosmetic benefit but it does not reduce the length of the hospital stay (LOS), postoperative pain, bleeding or operation costs. Bonacchi et al. [35], in contrast, come to a different conclusion. Beyond the reduction of surgical and wound pain and a decreased blood loss and faster recovery of respiratory functions, they also report a shorter intensive care unit stay (ICU) and LOS. Also controversial are data regarding the use of the ministernotomy approach in children. While Laussen et al. [39] report that the ministernotomy does not enhance the postoperative outcome, Luo et al. [40], in contrast, report that it reduces the LOS and bleeding, but with a longer operative time. 3.3. Treatment of aortic root through ministernotomy In the literature, there are not many reports on treatment of aortic root disease through a minimally invasive approach [27–31, 36, 37, 41–44]. Furthermore, few authors treat aortic root disease with a Bentall–De Bono operation through a ministernotomy [25, 30, 41].Klokocovnik [41] reported one case of this procedure. Perrotta et al. [30] reported on a series of 40 patients, treated between September 1997 and June 2005. These patients had a diagnosis of aortic root aneurysm and aortic valve insufficiency and underwent a Bentall–De Bono operation through a ministernotomy approach. It should be pointed out that in this group of patients, three had an acute type A aortic dissection. This shows that the ministernotomy can also be used for acute severe pathology, such as a type A aortic dissection. In the Perrotta series, 37 patients underwent a Bentall–De Bono operation through an upper J incision while the other three received a reversed T ministernotomy. The author registered only one in-hospital mortality, 46 days after surgery. The late survival at 1, 3, and 5 years was, respectively, 94.1%, 90.6%, and 90.6%. Another review of eight cases was presented by Sun et al. [25]. They compared the results of treatment of the aortic root and ascending aorta aneurysm with the Bentall–De Bono procedure using a minimally invasive approach or a complete sternotomy. They reported shorter CPB and aortic cross-clamp (ACC) times in comparison to the series of Perrotta et al. These differing results may be due to differences among the treated patients. Sun et al. included in their report eight selected patients with a diagnosis of Marfan syndrome and moderate aortic valve regurgitation. All had an elective surgery, none was a re-operation and none had a concomitant surgery. Perrotta et al. on the other hand, also included patients with ascending aorta dissection, redo-operations and patients operated under emergencies. Furthermore, they included three patients with concomitant surgery: two received a partial arch replacement and one received a coronary artery bypass graft. In their series, the patients were older and, in particular, 35% were more than 60 years old. In Perrotta's series, three patients required long-term assisted mechanical ventilation with a tracheotomy. This reflected a longer mean time of assisted mechanical ventilation, however, the median time of assisted ventilation is similar to the one reported by Sun et al., as well as the ICU time and postoperative bleeding. The largest experience on treatment of aortic root disease through a ministernotomy is reported by Tabata et al. [36]. They included 67 patients who underwent aortic root surgery. Among them, 57 received a homograft in an aortic position and 6 had a Bentall–De Bono operation. Some of these patients had concomitant surgery on the heart and on the aortic arch. They reported 0% surgical mortality and a low incidence of postoperative complications. A great contribution in understanding the benefits of the minimal invasive approach in surgery of the ascending aorta is given by Svensson [7, 27, 28, 44]. In a case-controlled study of 74 patients, Svensson and D'Agostino [44] selected 37 subjects who consecutively underwent minimal access operations (18 aortic valve, including one mitral valve operation; 6 composite valve grafts, including one arch and one transaortic mitral valve operation; 2 ascending aorta operations; 3 aortic root repairs; 7 mitral valve surgeries, including one Maze operation; and one atrial septal defect). The patients were matched by sex, age, surgeon and operation with 37 controls who had standard incisions. In their study, patients with minimal access incisions were associated with shorter LOS. The postoperative pain appeared to be less, requiring less intravenous narcotics, and patients were discharged earlier. Furthermore, results of standard vs. minimal access incisions were comparable in terms of safety and neurological outcome. In a second study, Svensson and colleagues [27] reported 54 cases of aortic surgery through upper hemisternotomy with an excellent early outcome. Their experience included 36 ascending aortic repairs, 18 ascending aortic and arch repairs, 26 concomitant aortic valve replacements, 15 concomitant composite valve graft aortic root replacements, and 18 re-operations. In that study, the mean CPB time was 132±59 min, ACC 91±45 min, and circulatory arrest 20±17 min. Operative mortality was 4%, the incidence of stroke 3.7%, and the mean LOS and ICU were 6.7±3.7 days and 1.8±1.9 days, respectively. In this study, they concluded that ministernotomy can be safely performed for ascending aorta and aortic arch surgery, and in particular is useful for redo cases. Furthermore, the same author [28] has reported on a series of 68 patients treated by ministernotomy for surgery of the aortic root, applying a protocol for stroke and neurocognitive deficit prevention in an attempt to prevent neurological deficits in patients undergoing ministernotomy. He reported only two patients with stroke and 98.5% survival. This author [27, 28] has reported the largest number of re-operative minimal access aortic surgeries and described that an upper hemisternotomy is particularly valuable in redo surgery in terms of avoidance of myocardial or graft injures. Other authors [36] have expressed the same consideration. In our experience, a limited surgical incision can be applied in redo-operations with good results. The exposure of only the required anatomical structures reduces the need for adhesion dissection on the heart and consequently the postoperative bleeding and the operative time. Furthermore, the ministernotomy may prove useful in patients undergoing isolated surgical aortic valve replacement with patent left internal mammary artery (LIMA) graft on the left anterior descending (LAD) artery [33]. Our group has used ministernotomy in 18 patients with patent LIMA with good results. Also Byrne et al. [29] have reported on 63 minimal access aortic surgeries through an upper hemisternotomy or parasternal approach, including 44 aortic root replacements, 9 aortic valve and supracoronary ascending aorta replacements, and 10 isolated ascending aorta replacements, with satisfying outcomes. They concluded that ministernotomy for aortic root and ascending aorta surgery is safe and effective, offering advantages in terms of both decreased blood loss and reduced surgical trauma, with good results both for morbidity and mortality.
The studies reviewed here show that aortic surgery in ministernotomy can be performed safely, although the outcomes of a minimal access approach and a conventional sternotomy were not always compared. It appears that the T or J ministernotomy, in patients with aortic root disease, is a feasible alternative to full sternotomy. The shorter incision, the reduced surgical dissection, the reduction in postoperative pain, the reduced bleeding and an early mobilization help the patient to obtain a faster postoperative recovery. However, there are still a limited number of studies comparing this approach to a full sternotomy in a prospective, randomized fashion. Furthermore, these series are made using a limited number of patients, and often performed by few surgeons. This is likely due to a long learning curve. Those factors could represent a limitation in giving a definitive judgement on this surgical approach. Further studies and a larger number of patients would be required to evaluate the real efficacy of this surgical approach. However, despite the different results reported, and the different opinions on the benefits of ministernotomy for the treatment of diseases of the aortic root and the ascending aorta, it seems that the use of the ministernotomy is slowly gaining consensus among surgeons. The indication to surgery, initially restricted only to selected elective patients, is now extended to redo-operations and in minor cases to emergency patients. The use of ministernotomy in redo aortic surgery with patent LIMA to LAD is a promising alternative [45]. Even the type of surgery performed is now extended to complex operations on the aortic root and arch. However, there are no reports yet on root remodelling or reimplantation [46–48], or new techniques of root remodelling [49, 50] performed in a ministernotomy.
In conclusion, we believe that the ministernotomy approach for aortic root and ascending aorta surgery could in the future be more extensively used, offering greater benefits to cardiac surgical patients.
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Abstract
1. Introduction