Aortic valve replacement via full sternotomy is the gold standard surgical therapy for patients with severe aortic stenosis (AS) and insufficiency.1 This procedure has proved to be reliable, reproducible, relieves symptoms and improves prognosis of the patients. Degenerative AS is the most frequently acquired valve disease in the elderly population. In the current era, aortic valve surgery is the most common cardiac valve intervention in a cardiac surgery department.2
Improvements in anaesthesia, surgical techniques, post-operative care and in methods of myocardial protection has allowed surgeons to treat patients with increased age and or comorbidity safely with a low rate of morbidity and mortality. Data reported from the Society of Thoracic Surgeon (STS) database have shown a dramatic in-hospital mortality reduction from 3.4 % in 1997 to 2.6 % in 2006 for isolated AVR.3 The number of patients requiring aortic valve evaluation and intervention are increasing as the population grows and becomes older.4,5
However, physicians remain reluctant to recommend AVR for elderly patients more than 80 years of age or those considered very high risk.6 Instead, many patients are continued on medical management or undergo a balloon aortic valvuloplasty.6 Unfortunately, these conservative therapies provide minimal or short-lasting symptomatic relief to the patient, eventually leading to restenosis of the aortic valve or sudden death.
As a result, new techniques and technologies have been developed to enhance these outcomes, particularly in high-risk complex patients. As in other fields of medicine, a trend towards minimally invasive surgery has swept into cardiac surgery to achieve better results for the patients with the same quality as conventional median sternotomy.
The STS database defines minimally invasive cardiac surgery as “any procedure not performed with a Full Sternotomy and cardiopulmonary bypass (CPB) support”.7,8 The only aortic valve procedure precisely represented by this definition is transcatheter aortic valve implantation (TAVI). In this setting, TAVI offers an alternative treatment option in high-risk patients, having demonstrated to be superior to medical therapy in non-operable patients and non-inferior to surgical aortic valve procedure. However, controversies still exist regarding its effect on post-operative outcomes compared with conventional surgery. A meta-analysis of randomised, controlled trials that included 3,465 patients with severe AS found no significant differences between TAVI and conventional AVR in terms of myocardial infarction, stroke and mortality.9 Conversely, a sub-group analysis showed a higher incidence of vascular complications, neurological events, aortic reg
urgitation and need for permanent pacemaker implantation in patients undergoing TAVI.9
In 2008, a scientific statement from the American Heart Association defined minimally invasive cardiac surgery as “a small chest wall incision that does not include the conventional Full Sternotomy”; however, CPB is still utilised.10 The first description of aortic valve replacement (AVR) through right thoracotomy was published in 1993.11 Minimally invasive approaches through mini-sternotomy was popularised by Cleveland Clinic in 1996 and progressively spread in the surgical community around the world.12,13
Historically different approaches has been described, and many types of classification, one as step wise approach for reduction of the trauma, from full incision sternotomy to non-incision sternotomy like right anterior mini thoracotomy (RAT) (see Figure 1). The most common techniques used today for minimal invasive aortic valve surgery (MIAVS) are RAT and upper hemisternotomy (UHS) incisions and hence those will be part of later discussion. Also, other approaches have been described, such as parasternal, transverse sternotomy and lower hemisternotomy.14–18
Different types of valves can be used, including standard mechanical and tissue valves. Stentless valve and sutureless valves can also be used in these minimally invasive approaches. Concomitant procedures, such as replacement of the ascending aorta and other valve interventions, have been described with these approaches as well.