Standardization for Minimally Invasive Combined Aortic and Mitral Valve Surgery via a Right Minithoracotomy

Abstract

Surgeons have been reluctant to adopt minimally invasive combined aortic and mitral valve surgery through a minithoracotomy because of its complexity and prolonged cardiopulmonary bypass and aortic cross-clamping times. Our technique was designed to provide a close and frontal surgical visual field without the need for long-shafted specialized surgical instruments, thereby allowing a standardized and well-visualized surgical visual field in many cases. Here we describe the implementation of our minimally invasive combined aortic and mitral valve surgical procedure through a right minithoracotomy facilitated by the superior septal approach for mitral valve access.

The main challenge of minimally invasive combined aortic and mitral valve surgery (CAMVS) is that, despite being anatomically continuous, the aortic and mitral valves lie on different planes and have different orientations. Therefore, it is impossible to visualize both valves frontally through a thoracic incision. We developed a minimally invasive CAMVS technique through a right minithoracotomy using the superior septal approach (SSA) for mitral valve access with a routine transverse aortotomy for aortic valve surgery.

Here we describe our experience with this CAMVS procedure and highlight some technical aspects and standardization of the approach.

Technique

CAMVS were performed under general anesthesia with differential lung ventilation. A 6- to 7-cm, slightly curved subnipple skin incision is made, followed by a thoracotomy at the fourth intercostal space using the Adams-Yozu Mini-Valve System (Geister). After full heparinization, cardiopulmonary bypass is established through the right femoral artery and vein, an additional venous cannula is positioned percutaneously into the right jugular vein the resected pericardium is pulled up by using four 2-0 braided polyester sutures to the right chest wall. Using an Endo Close needle-suture device (Covidien), the sutures are pulled 3 to 4 cm away from the wound and are strongly ligated to a short, split Nelaton tube catheter. It is particularly important to draw the aortic root toward the right chest wall while positioning it slightly to the right of the center of the surgical visual field. Aortic cross-clamping is performed using a Cygnet Flexible Clamp (Vitalitec) from within the wound. Cardiac arrest is achieved by infusing antegrade or selective cold blood cardioplegia, depending on the presence of aortic valve regurgitation, and a left atrial roof incision is made for the SSA. To minimize the risk of the sinoatrial node artery injury, we routinely direct the atrial incision toward the left superior pulmonary vein, thereby avoiding complete transection of the artery. Aortic and mitral valve surgery can then be easily performed because of the short intervalve distance and the right-opened chest wound with a good surgical visual field (Videos 1, 2).

We have performed our procedure in 9 patients (6 men, 3 women; mean age, 67.2 years [range, 25-86 years]). The mean (SD) height was 159 (10.5) cm, weight was 56.9 (9.7) kg, and body surface area was 1.59 (0.18) m². Two patients had degenerative aortic stenosis, and 7 had aortic regurgitation. Regarding mitral valve disease, 2 patients had rheumatic stenosis, and 7 had degenerative regurgitation. All patients underwent aortic valve replacement. Mitral valve replacement was performed in 5 patients: 2 with rheumatic stenosis, 2 older patients (aged >80 years), and 1 patient with extensive Barlow disease. The remaining 4 patients underwent mitral valve repair. No paravalvular leakage was observed. Two patients underwent a left atrial appendectomy, and 1 patient underwent a tricuspid annuloplasty. The prosthetic aortic and mitral valves and annuloplasty ring or band were tied using the fingertips, without knot pushers. Specialized long-shafted instruments were not used. The mean cardiopulmonary bypass and aortic cross-clamp times were 236.1 (20.4) and 171.6 (16.5) minutes, respectively. The mean total operative time was 348.8 (34.5) minutes. There were no hospital deaths or major complications. Two patients had junctional rhythm for several days postoperatively but remained in sinus rhythm at discharge and did not require permanent pacemaker implantation.

Comment

We combined the Stonehenge technique for aortic valve surgery with the drawer-case technique for mitral valve surgery, which we previously reported,^1,2 and found that mitral valve surgery can be easily performed using the SSA with a closer and larger surgical working space.

There are 2 major obstacles for CAMVS through a restricted open chest wound. The first obstacle is that the 2 valves lie on different planes and have different orientations (Figure 1A). Consequently, if the surgical visual field is centered around the mitral valve, aortic valve access becomes challenging, particularly between the right coronary cusp and the noncoronary cusp.

Figure 1.

(A) The aortic, mitral, and tricuspid valves lie on different planes with distinct orientations. Viewed through a right-sided left atrial incision (black arrow), the mitral and tricuspid valves are well visualized, but the aortic valve remains obscured. A superior septal approach (white arrow) aligns both the mitral and aortic valves in the same field. (B) A right-sided left atrial incision is optimal for mitral valve access through a right minithoracotomy, but in the combined aortic and mitral valve surgery, securing adequate aortic valve exposure is difficult despite various aortotomy modifications. (C) The superior septal approach involves opening the left atrium roof, allowing easy access to both the aortic and mitral valves, which are oriented in different directions. In (B) and (C), the green check marks and red divided circle indicate “correct technique” and "incorrect technique", respectively.

For 2-valve surgery through a right minithoracotomy, aortic valve replacement is typically performed through a transverse or oblique aortotomy, whereas mitral valve surgery is conducted through a right-sided left atrial incision. However, this approach can compromise the aortic valve surgical visual field in favor of the mitral valve surgical visual field (Figure 1B).

In this regard, the SSA is useful for mitral valve access. Although there are slight risks for junctional rhythm, the left atrial roof incision enables mitral valve surgery along the same visual axis as the aortic valve, thereby significantly improving surgical accessibility (Figure 1C).

The second obstacle consists of the long surgical distance and optimal positioning of both valves for surgery through a right minithoracotomy. Regardless of how well the valve axis alignment and frontal view are achieved, the procedure cannot be performed safely unless both valves are positioned optimally within the surgical visual field.

Bringing the target site closer to the right chest wall wound by using pericardial retraction sutures is crucial for reducing the surgical difficulty and cardiac arrest time. However, the most important aspect of the technique is positioning the aortic root slightly to the right of the center of the surgical visual field while drawing it toward the right chest wall (Figure 2, Figure 3).

Figure 2.

The most important aspect of our combined aortic and mitral valve surgery technique is to position the aortic root slightly to the right of the center of the surgical field while drawing it toward the right chest wall. (A) This positioning allows optimal frontal visualization of the aortic valve after the aortotomy. (B) If the aortic root lies left of center, the aortic wall can obstruct the aortic valve visibility, thus obscuring the right coronary cusp–noncoronary cusp commissure and increasing the procedural difficulty. In (A) and (B), the green check mark and red divided circle indicate “correct technique” and “incorrect technique”, respectively. In addition, the diagrams with arrows in (A) and (B) represent enlarged views to clearly illustrate the appearance of the aortic valve.

Figure 3.

(A) With the aortic root in the optimal position, pericardial traction (arrow thickness) can be applied directly with full force toward the right chest wall along the shortest path. (B) If the aortic root is cranial or caudal relative to the optimal position, retraction sutures adjust its position by pulling it downward from a cranial position or lifting it upward from a caudal position. Traction force comprises a lateral component toward the chest wall and another component toward the field center; achieving optimal centering may require a slight reduction of the lateral force. In (A) and (B), the white arrows indicate the appropriate direction for positioning the aortic root within the surgical visual field.

We routinely perform 3-dimensional reconstructions of preoperative computed tomography to assess the spatial orientation of the aortic root, valves, and left atrial roof, to guide intercostal space and incision selection and determine whether pericardial retraction alone or minor cranial or caudal adjustments—as small as one-half of an intercostal space—are required.

In obese patients, cranial displacement of abdominal organs in the supine position elevates the diaphragm and causes horizontal and counterclockwise rotation of the heart. In these patients, even careful caudal traction often fails to restore optimal orientation, thus impairing posteromedial mitral leaflet visualization. This anatomy also complicates mitral valve exposure through a standard right-sided left atrial incision, particularly when the left atrium is nondilated. However, the SSA consistently provides excellent visualization in these challenging scenarios and is particularly advantageous for CAMVS through a right minithoracotomy, even in obese patients.

Overcoming these obstacles is synonymous with securing a clear surgical visual field and reducing the procedural difficulty for CAMVS through a right minithoracotomy. It also contributes to standardization of the approach, by enabling consistent 2-valve surgical interventions across patients with varying thoracic structures, heart sizes, and ascending aortic anatomies. Moreover, the right atrial incision simplifies the tricuspid valve access for annuloplasty performance or combination with antegrade or retrograde myocardial protection. This standardized method for achieving an optimal surgical visual field has the potential to become a generally accepted option for minimally invasive CAMVS through a right minithoracotomy.

In conclusion, CAMVS through a right minithoracotomy using the SSA for mitral valve access is both feasible and safe. It provides a close and frontal surgical visual field without the need for long-shafted specialized surgical instruments and thus allows a standardized and well-visualized surgical visual field in many cases.

Supplementary Data

Video 1

Overhead camera view of the surgical procedure.

Video 2

Head-mounted camera view of the surgical procedure.