Methods
Patients
From 1996 to 2013, 22,766 patients underwent aortic valve operations (including reoperations and multi-component procedures) at the Cleveland Clinic. Of these, 3,385 (15%) have been performed with a minimally invasive approach. All patients undergoing cardiac surgery at the Cleveland Clinic are entered into the Cardiovascular Information Registry (CVIR), which includes a collection of preoperative demographic and comorbidity data, indications for surgery, operative variables, in-hospital complications, and operative mortality. Routine telephone follow-up is available for those patients with a surgery date before 2012. Survival data has been supplemented with Social Security Death Index data. All aortic valve operations regardless of type were included in the cohort for analysis.
Interventions
Incision selection for valve surgery has been at the discretion of the surgeon without a formal algorithmic approach. In the early years after the introduction of MIAVS to the Cleveland Clinic, minimally invasive surgery was largely performed by a small subgroup of surgeons. However, recent trends show surgeons utilizing minimally invasive approaches for isolated aortic valve disease. Patient outcomes for standard and minimally invasive surgery are reviewed on a regular basis at monthly quality staff meetings. All mortalities undergo a formal presentation and review by the staff. Trends in major morbidity are reviewed in detail and have led to continuous refinement of surgical techniques, perfusion, and protection strategies.
For patients requiring isolated valve surgery at the Cleveland Clinic, minimally invasive approaches dominate and the specific incision is tailored to the patient based on the valve involved, morphology of disease, patient-specific anatomy, and surgeon preference (Figure 2). Most patients with a primary indication for aortic valve surgery are amenable to a MIAVS approach, so a description of contraindications or relative contraindications is worthwhile. The need for coronary revascularization is usually a contraindication to MIAVS, although some patients have undergone hybrid aortic valve replacement (AVR) plus percutaneous coronary stenting, while several others have had right coronary bypass grafting at the time of MIAVS. Emergency operations for endocarditis or acute proximal aortic dissection are routinely performed through a full sternotomy. Although reoperations have been performed using MIAVS techniques, we have considered it a relative contraindication in recent years, given the potential risks of less than ideal cardiac protection in relation to potential benefits. Finally, although aortic root replacement is frequently performed through a mini incision, when the patient is planned for a modified David's reimplantation procedure or Ross procedure, we have preferred the exposure provided by a full sternotomy approach.
Figure 2.
Distribution of isolated valve surgery approach at the Cleveland Clinic in 2013.
All other patients, including those requiring aortic replacement with or without circulatory arrest, multi-valve operations, and even those with atrial fibrillation or severe comorbidities, are candidates for a MIAVS approach.[5,6]
Standard preoperative cardiac workup has included plain chest radiography, coronary angiography, and routine laboratory studies in addition to echocardiography. Cardiac computed tomography is obtained selectively, usually for patients with suspicion of concomitant aortic disease or those being considered for right anterior thoracotomy.[7]
Surgical Technique
Early in the experience, a number of cases were performed via a right parasternal approach involving resection of the 2nd and 3rd costal cartilage.[3] The majority of cases have since been performed with an upper hemisternotomy. Briefly, a 7–10 cm skin incision is made with the upper sternum divided and bone incision carried into the right 4th interspace or, occasionally, to the 3rd interspace. In a minority of cases, a "T" incision extending to the left interspace was made in order to facilitate exposure for concomitant mitral valve surgery. Alternatively, a lower hemisternotomy was performed due to a particularly low position of the aorta within the chest. Femoral arterial cannulation was used routinely in the early experience, but is now rarely employed for upper hemisternotomy. Axillary cannulation using a Dacron side graft is used selectively for those patients requiring arch reconstruction or in the presence of severe aortic calcification. Upper hemisternotomy also facilitates placement of the venous cannula via the chest incision. Venous cannulation is usually accomplished directly via the right atrium, or through the superior vena cava with a 3-stage cannula. For right anterior thoracotomy cases, venous cannulation is peripheral via the femoral vein, and for a few patients this also may be used for the upper hemisternotomy incision. Femoral artery cannulation has been used in a minority of cases, with the current preference being for direct aortic cannulation even with the right anterior thoracotomy approach, based on the favorable experience of a number of authors, including Glauber.[8]
Myocardial protection was most often achieved with both antegrade and retrograde modified Buckberg cardioplegia, with the retrograde cannula placed through the incision without echocardiographic guidance. More recently, single dose Del Nido cardioplegia has been employed for most isolated valve cases, obviating the need for placement of the retrograde cannula into the coronary sinus. Conduct of the operation for a hemisternotomy case is similar to that during a full sternotomy aortic valve surgery, using standard instruments and procedures. Longer handled endoscopic instruments are utilized for mini-thoracotomy cases, and the Cor-Knot device (LSISolutions, Victor, NY) is commonly used for suture placement for AVR.
Statistics and Follow-up
Data were retrieved from the prospective CVIR and from patients' medical records, supplemented with information from the Echocardiography database. These data were approved for use in research by the institutional review board, with patient consent waived. All previous Cleveland Clinic studies involving aortic valve surgery and/or minimally invasive valve surgery were reviewed. Trends in the utilization of minimally invasive approaches, concomitant procedures performed, and outcomes for aortic valve surgery are presented as simple trends. Propensity matched outcomes for minimally invasive vs. standard aortic valve surgery for subsets of patients are presented as previously described.[9]
Ann Cardiothorac Surg. 2015;4(2):140-147. © 2015 AME Publishing Company
