Do patients want minimally invasive aortic valve replacement?

Abstract

Objective: Access to aortic valve can be performed through small incisions. However, a considerable advantage of this approach has not been proven by randomized studies so far. We wanted to elucidate the opinion of patients when they are informed objectively about advantages and disadvantages of minimally invasive approach prior to operation. Methods: This prospective study was performed with 27 patients undergoing isolated aortic valve replacement. These patients were informed prior to operation by the same resident concerning objective data. A photograph was shown illustrating a patient with postoperative wound after a standard- and a mini-incision, respectively. After the interview the patient could decide between full and partial sternotomy. Results: After the interview 21/27 (78%) patients preferred to have a full sternotomy (group F) and 6/27 (22%) patients (group P) decided to have a partial sternotomy. Comments of group F: surgeon should have best exposure (n=15); cosmetics aspects unimportant (n=14); operation time as short as possible (n=7). Group P: cosmetic aspects important (n=6). Significant differences between groups (group F vs. group P): age (years), 69.1±1.5 vs. 49.2±7.3 (P=0.024); operation time (min), 142±7 vs. 189±15 (P=0.002); CK (IU/l), 111±11 vs. 374±114 (P=0.0007); CKMB (IU/l), 17±2 vs. 45±17 (P=0.006); ICU-stay (days), 2.6±0.2 vs. 3.2±0.2 (P=0.044). Pericardial effusion requiring drainage was observed in two patients of group P. One patient of group P suffered myocardial infarction. Conclusion: When patients are informed objectively about advantages and disadvantages of minimal invasive aortic valve surgery only a smaller number decides to have a mini incision. The patients preferring short incisions are significantly younger since cosmetic aspects are more important. Longer duration of operation may be due to longer hemostasis based on limited exposure. Air bubbles due to inadequate de-airing might be responsible for higher CK and CK-MB levels in group P.

Minimally invasive, Aortic valve, Surgery

1 Introduction

For about 5 years there has been a trend to perform aortic valve surgery using minimally invasive techniques in order to reduce surgical trauma. Several incisions have been described. At present, a partial upper sternotomy is the most frequently used incision for minimally invasive approach to aortic valve. Up to now there are only two randomized studies comparing minimally invasive approaches versus median sternotomy [1,2]. However, opinion of patients regarding minimally invasive surgery is unknown especially when they are informed objectively prior to operation. This study was undertaken to explore the opinion of the patients concerning minimally invasive aortic valve surgery.

2 Materials and methods

Prior to this study 28 patients had aortic valve replacement through upper partial sternotomy for better understanding of potential technical problems. After this initial experience differences between full and partial sternotomy were defined. Thereafter this prospective study was initiated. Between December 1998 and July 1999 an isolated aortic valve replacement was performed in 124 patients. In 97/124 (78%) patients total sternotomy was performed either due to surgeons reluctance to use a minimal approach or due to different medical reasons (Table 1) . In total 27/124 (22%) patients were included in the study. The observations made from the initial experience were told to the patients by the same resident (Table 2) . Thereafter a photograph was shown to the patient illustrating full sternotomy and partial sternotomy wound (Fig. 1) . After interview the patient had to decide between full sternotomy (group F) and upper partial sternotomy (J-cut) (group P).

Table 1

Exclusion criteria for minimally invasive surgical approach

Table 2

Information given to patients preoperatively

Fig. 1

Photograph shown to every patient preoperatively during the interview.

2.1 Surgical technique

In group F standard full sternotomy was performed and in group P an 8–10 cm incision was carried out. Ascending aorta and right atrial appendage was cannulated as usual After institution of cardiopulmonary bypass aorta was cross-clamped and either cold blood cardioplegia or Bretschneider cardioplegia was infused. Aortic valve was excised and replaced by either a mechanical (n=18) or biological (n=9) valve prosthesis. Transesophageal echocardiography was used in each patient undergoing minimally invasive procedure in order to prevent ventricular distension and to visualize intraventricular air bubbles. After de-clamping, de-airing was performed either by puncture of left ventricular apex (group F) or partial aortic clamping (group P). Ascending aortic vent was positioned in both groups. The sternum was closed with steel wires.

2.2 Statistical analysis

Data are given as mean±standard deviation (SD). Differences of variables between both groups were calculated using the Mann–Whitney U-test or Fisher's exact test where appropriate. P-values ≪0.05 were considered significant.

3 Results

After the interview 21/27 (78%) patients decided to have a full sternotomy and 6/27 (22%) patients preferred partial sternotomy. The patients comments for their decisions are listed in Table 3 . Pre-, intra- and postoperative data are summarized in Table 4 .

Table 3

Patients comments after the interview (multiple answers were given)

Table 4

Preoperative demographics, perioperative variables and operative morbidity

Exposure of aortic valve was adequate in every patient. Conversion from partial to full sternotomy was not necessary in any case. Cannulation of ascending aorta and right atrium was possible in each patient. In one case with partial sternotomy the right internal mammary artery was injured. In group F 13 mechanical and eight biological valves were implanted, whereas in group P five patients received mechanical valves and one biological valve.

There was no early mortality in both groups. Pericardial effusion which required drainage occurred in two patients of group P. One patient of group P experienced myocardial infarction. Wound infection and sternal instability was not observed in either group. All patients who wished to have partial sternotomy were male. Mean age (male vs. female) was 61±14.5 vs. 70±8.6 (NS).

4 Discussion

In the last 5 years there has been a trend toward performing heart surgery minimally invasively at least in patients who qualify for this new technique. Different minimal access incisions have been proposed for aortic valve replacement such as upper sternotomy with partial or full sternal transsection, right parasternal incision or transverse sternotomy [3–5]. At present the upper partial hemisternotomy (L-shaped sternotomy) is the most frequent approach to access the aortic valve. One advantage of the partial sternotomy is preservation of integrity of thoracic cage. This may decrease the risk of sternal instability although this has not yet been proven. Small incisions may also help patients psychologically because patients seem to equate the magnitude of the operation with the size of the incision. Furthermore, small incisions are becoming an expectation especially of young patients.

The goals of the minimally invasive surgical approach to aortic valve are more rapid recovery, shorter hospital stay, less patient morbidity, faster return to routine activity, increased patient comfort, cosmetic benefit and cost containment. However, there are only few randomized studies dealing with these topics [1,2,6].

Apart from possible advantages of mini-sternotomy there are definite disadvantages of this approach which we tried to define when performing the first 28 patients. These are not included in this study. There is limited exposure of the right and left ventricle, de-airing procedure is difficult and both aortic cross-clamp time and CPB-time is increased. In some cases internal mammary artery must be ligated. Furthermore, insertion of coronary sinus catheter for retrograde cardioplegic delivery is sometimes impossible.

In our opinion, the patients should be informed correctly prior to operation which means that not only advantages but also disadvantages must be outlined. Although we did not mention the de-airing problems which could increase rate of neurologic complications majority of patients decided to have a full sternotomy. The main arguments were that the surgeon should have best exposure to the heart and that operation-time should be as short as possible. One can argue that with time duration of aortic cross-clamping and CPB will decrease as was the case in our series. Indeed, there are other studies presenting identical cross-clamp and CPB times when comparing conventional approach and minimally invasive approach [1,4]. However, others report longer ischemic- and CPB-times for minimally invasive aortic valve replacement [2,5]. Total operation time was longer in our patients since blood stanching was more difficult due to limited exposure of cardiac structures.

Cosmetic aspects were unimportant for most patients although we showed them a photograph comparing conventional and short skin incisions. The patients deciding to have a mini-incision were significantly younger and for these patients a small incision is certainly advantageous. Small skin incisions are also possible when performing full sternotomy as proposed by Akins [7]. This incision is 8–10 cm in length compared to 6–9 cm incisions used for mini-sternotomy.

Levels of CK and CK-MB were significantly higher in patients undergoing minimally invasive approach. Since there were only six patients in this group interpretation is difficult. It might be possible that air bubbles temporarily occluded coronary arteries due to incomplete de-airing.

The patients were not interviewed regarding postoperative pain. However, it was the impression that pain was identical in both groups. One patient undergoing mini-sternotomy had intense postoperative pain. There is a controversy regarding postoperative pain after minimally invasive aortic valve replacement. Some authors state that full sternotomy is superior to minimal access incision with regard to pain [8,9]. Aris et al. did not find any difference concerning postoperative pain between full and partial sternotomy in a prospective randomized study [2]. Autschbach et al. measured postoperative pain on a daily basis during the first postoperative week using a visual scale and could not find a difference between minimally invasive and conventionally operated patients as well [6]. However, others think that there is less pain after minimal access surgery, although objective data are not presented in these studies [1,4,10].

Only large prospective randomized studies with midterm follow-up can demonstrate advantages and disadvantages of minimally invasive aortic valve replacement. The patient should be informed that such studies do not exist and that the only proven advantage of minimally invasive approach is the shorter incision which is cosmetically superior compared to full sternotomy. Based on this information the patient should be allowed to decide on his own.

✩

Presented at the 13th Annual Meeting of the European Association for Cardio-thoracic Surgery, Glasgow, Scotland, UK, September 5–8, 1999.

Dr M. Murtra (Barcelona, Spain): As far as I am concerned, I can tell you that in our series, the most important factor, as far as comfort postop, was how much we opened the sternum. Never mind the skin incision or whatever you do, what is important is if you're opening more than 8 cm or 7 cm, the discomfort is very high. So I wonder if probably your last conclusion is the best one, small skin incision and full split of the sternum.