What’s New in Mitral Valve Repair?

Article Citation:

Daniel J. DiBardino and R. Saeid Farivar (2017) What’s New in Mitral Valve Repair?. Journal of the Minneapolis Heart Institute Foundation: Fall/Winter 2017, Vol. 1, No. 2, pp. 108-112.

Original Article

Daniel J. DiBardino, MD

R. Saeid Farivar, MD, PhD

Abbott Northwestern Hospital, Minneapolis, MNAddress for correspondence:
R. Saeid Farivar, MD, PhD
Cardiothoracic Surgery
Abbott Northwestern Medical Center
920 E 28th Street, Suite 400
Minneapolis, MN 55407

E-mail: farivar@gmail.com

ABSTRACT

Mitral valve repair is the standard of care for degenerative mitral valve pathology, as established by the median sternotomy approach. Equivalently excellent results can be achieved by a variety of more minimally invasive approaches depending on institutional experience and preferences. At the Minneapolis Heart Institute®, we have experience with and utilize all approaches to mitral valve repair for degenerative disease including full and hemisternotomy, right thoracotomy, mini-thoracotomy and heart port approaches. We believe that logistic, economic, and anticipated benefit constraints currently limit the application and the robotic technology. Leaflet maneuvers continue to be important in mitral valve repair, but recently we have revisited the concept of simplifying a “complex” repair in the setting of a subset of severe degenerative (Barlow’s) disease by utilizing only an oversized mitral valve ring with excellent results. As suggested by others, in the appropriate setting of bileaflet prolapse resulting in central symmetric regurgitation, a simplified approach may be just as effective as longer, more complicated operations.

Keywords: mitral valve repair

INTRODUCTION

The first successful mitral valve (MV) operation was performed in 1923 by Dr. Elliot Carr Cutler at the Brigham and Woman’s Hospital in Boston, MA, and is one of the oldest operations in the history of cardiac surgery.1 Harken and colleagues continued this tradition in Boston in the 1940s and 1950s with closed MV repair, eventually leading to the start of a contemporary MV repair program with open repairs performed on cardiopulmonary bypass (CPB) beginning in 1972.2 Over the next 30 years, the contributions from Boston, Paris, and Ann Arbor (as well as others) have established mitral valve repair as the preferred operation for degenerative mitral valve pathology. Working through traditional median sternotomy incisions and central CPB cannulation techniques, they have established the foundations of mitral valve repair and the expected outcomes in degenerative mitral pathology. These tenets include2:

1. Degenerative MV disease can be repaired in the majority of cases with a durable long-term result and very low reoperative rate. Experienced centers can reproducibly expect repair rates of over 90% with a 1% failure rate/year.
2. The life expectancy curves for those that undergo repair approach those of the normal life expectancy curves for men and women, and in certain cases may be better than twins without the disease.
3. The repair techniques include a finite list of leaflet maneuvers and should always include the placement of a ring for annular fixation. The leaflet maneuvers include various resections, plications, commissure, and cleft closures; edge-to-edge repairs; and artificial chord placement based upon the findings of the echo and the appearance of the degenerative pathology at the time of surgery.

Given the evolution and success of these surgical tenets, the American College of Cardiology/American Heart Association guidelines have recommended MV surgery for symptomatic MR and minimally symptomatic MR in the presence of left ventricular dilation or dysfunction, and—at centers of excellence—can be considered for asymptomatic patients. Secondary to these recommendations, an estimated 40,000 MV operations take place in the US per year; given the low prevalence of rheumatic disease in the US, the majority of these patients are sent to surgery with MR and the majority of them are potential candidates for MV repair rather than replacement.The Minimally Invasive Era

Spurred in part by the adoption of the laparoscopic cholecystectomy, the concept of “minimally invasive” became a worldwide buzzword in all aspects of surgery in the 1990s. The success of the sternotomy approach for MV repair led cardiac surgeons to consider the application of minimally invasive surgical approaches to degenerative mitral pathology. Some of the first large-scale applications were the use of the parasternal and lower-hemisternotomy incisions by McClure and colleagues.3,4 The data show that the exact same results as with sternotomy can be achieved through these smaller incisions.

With the current understanding that the results are uncompromised, the benefits remain controversial. The use of smaller incisions and peripheral CPB cannulation techniques clearly result in cosmetic benefit (which younger patients appreciate), the benefit of increased sternal stability, and a theoretically easier reoperation in the future. As covered in a recent review, data from upper hemisternotomy and mini-thoracotomy aortic valve operations have consistently found a lower blood transfusion requirement and variability, a decreased incidence of atrial fibrillation, and lower length of ICU and hospital stay.5

At the same time as the lower hemisternotomy was explored in Boston and elsewhere, the historical use of a right thoracotomy incision for intracardiac surgery inspired others to pursue the use of right mini-thoracotomy incisions with modified central or peripheral cannulation techniques for minimally invasive approach to MV repair. Port access platform (originally “Heart Port” access); minimally invasive MV surgery; and robot-assisted MV surgery are more advanced, organized variations on the right mini-thoracotomy approach. Since the mid-1990s, institutions have perfected their own individual variations of these approaches. This has resulted in excellent success rates and allows operating on higher risk groups including those with left ventricular dysfunction and reoperative scenarios.6–13

While a very small number of centers have applied robotic technology and achieved equivalent results in the setting of posterior leaflet pathology,14 a recent review echoes the voice of the majority of cardiac surgeons. In sharp contrast to urologic and obstetric surgery, the logistic, financial, and other constraints of the current generation of robotic technology have limited this approach.15The Minneapolis Heart Institute® (MHI) Approach

At MHI, our structural heart surgical team has had training and experience in sternotomy, hemisternotomy, and port access techniques. In general, the port version of the right mini-thoracotomy approach is currently preferred over the lower hemisternotomy secondary to the optimal valve visualization. We look to this approach in presence of the following criteria:

1. No surgical coronary artery bypass required based on coronary angiography;
2. Isolated mitral valve disease (no intervention on tricuspid or other valve necessary);
3. Patient does not meet criteria for the application of additional surgery for atrial fibrillation (aka a “Maze” procedure variation); and
4. Patient is not at the extremes of age or body surface area.

If any of the above are not met, the patient is approached through a traditional median sternotomy or lower hemisternotomy. Our current port system setup generally includes the following elements:

1. Percutaneous femoral vessel access for peripheral cannulation for CPB;
2. Dual lumen endotracheal tube intubation;
3. Right inframammary incision to achieve mini-thoracotomy in the 5th intercostal space, application of the soft tissue retractor and the endoboy camera holder;
4. Femoral artery endoclamp catheter placement and positioning with transesophageal echo guidance;
5. Establishment of CPB and confirmation of adequate drainage and flows, and initiation of cooling;
6. Opening of pericardium, placement of stay sutures and dissection of the groove between the left and right atrium (Waterston’s groove);
7. Endoclamp balloon inflation and administration of antegrade cardiopledgia via cardio side port while monitoring root pressure and radial artery pressures; and
8. Waterston’s Groove approach to the MV repair using the port access system (Figure 1).
FIGURE 1
Port access system with resultant scar. Femoral venous and arterial CPB is initiated, with Endoclamp access and central cardioplegia. It is possible to place a retrograde coronary sinus catheter via the left neck, although currently we use a single shot antegrade cardioplegia model.

Recent Developments: an Older Concept Revisited

Gillinov and colleagues16 previously suggested years ago that a subset of patients with severe, complex degenerative mitral valve pathology (Barlow’s disease) and bileaflet prolapse may be successfully repaired only with posterior leaflet resection and annular ring fixation. It is important to recognize that the patients in this series were selected secondary to having no major anterior chordal pathology, but all had bileaflet prolapse in the setting of degenerative MV disease. We have recently taken this step toward simplification even further and applied only a ring annuloplasty to patients with Barlow’s MV pathology and bileaflet prolapse that resulted in a central, symmetrical jet of regurgitation.

In one recent example, a 34-year-old local police officer presented with degenerative MV pathology in the form of bileaflet prolapse resulting in a central, symmetrical jet of regurgitation (Figure 2). A 34-mm rigid complete annuloplasty ring was applied via the above described port approach, resulting in no residual mitral regurgitation (Figure 2). We have now applied this in other cases of central bileaflet prolapse, each time achieving an excellent result in this highly selected patient population.

FIGURE 2
Central bileaflet prolapse in the upper-left figure (Barlow’s), which is shown repaired below with good coaptation reserve on the 1-year follow-up echo. The incision is shown and the return to work photo.

SUMMARY

Mitral valve repair is the standard of care for degenerative MV pathology, as established by the median sternotomy approach. It provides durable, safe symptomatic relief, as well as quantity and quality of life. Equivalently excellent results can be achieved by a variety of more minimally invasive approaches depending on institutional experience and preferences. At MHI, we have experience with and utilize all approaches to MV repair for degenerative disease including full and hemisternotomy, right thoracotomy, mini-thoracotomy and heart port approaches. We believe that logistic, economic, and anticipated benefit constraints currently limit the application and the robotic technology. Leaflet maneuvers continue to be important in MV repair, but recently we have revisited the concept of simplifying a “complex” repair in the setting of a subset of severe Barlow’s disease by utilizing only an oversized MV ring with excellent results. As suggested by others, in the appropriate setting of bileaflet prolapse resulting in central symmetric regurgitation, a simplified approach may be just as effective as longer, more complicated operations.

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