Preoperative assessment and surgical techniques
Heart valves function was assessed by transthoracic and transoesophageal echocardiography. In the early years of our experience all patients underwent preoperative CT angiogram of the whole aorta to evaluate femoral access, aorto-iliac axes and the size of aortic root and the ascending aorta. In the last four years, CT scan was performed only in case of redo procedures and clinical suspicion or evidence of severe atherosclerotic disease. Coronary arteries were assessed by coronary angiogram.
Most of the operations (93%) on the atrioventricular valves in our institute were performed through right mini-thoracotomy (MICS). In some cases, median sternotomy was performed.
Main reasons for a sternotomy approach were: left ventricular ejection fraction<25%, presence of pleural adhesion for previous thoracic operations or chronic disease, severe chronic obstructive pulmonary disease, severe peripheral arterial disease, active endocarditis with abscess involving the mitro-aortic continuity [1].
Right anterior thoracotomy was performed through a 5-7 cm skin incision placed at 4th intercostal space. In men, the incision is usually immediately above the nipple. In women with pronounced breasts the incision can be made in the sub-mammary sulcus. In the case of a small and not very pronounced breast in women and in all men, a periareolar incision can be made. Two trocars were used, one for the camera in the third intercostal space, and one for CO2 delivery in the fifth space.
At the beginning of our experience, the surgical operation was performed on direct vision and video assistance, while, recently, we have move towards a totally endoscopic procedure (n=17, 25%).
All interventions were performed with cardiopulmonary bypass with peripheral cannulation.
An incision of about 4 cm was performed at the level of the groin, with exposure of the femoral vessels. The femoral artery was cannulated using the Seldinger technique with a 17-19 Fr Bio-medicus cannula (Medtronics, Minneapolis, MN 55432-5604 USA) or a 22 EOPA cannula (Medtronics, Minneapolis, MN 55432-5604 USA). The choice of cannula was determined by the diameter and characteristics of the femoral artery. When an endo aortic balloon was used, the femoral artery was cannulated with a 21-23 Fr EndoReturn cannula (Edwards Lifesciences, Irvine, CA 92614 USA).
Aortic clamp and cardioplegia delivery was achieved by Endoaortic balloon or direct cross clamp of the ascending aorta with a Chitwood or a Cygnet vascular clamp. In the first scenario a Y shaped 21 or 23 F cannula was used. The decision between these two different techniques was based on the anatomy of the sinotubular junction, the aorto-iliac-femoral anatomy and chest conformation. Generally, all redo operations were performed using an endobaloon aortic clamp.
A double venous cannulation has been invariably used. A 14 Fr cannula (Medtronics, Minneapolis, MN 55432-5604 USA) was usually inserted percutaneously and with the Seldinger technique into the right internal jugular vein and advanced into the superior caval vein. Through the femoral vein a 23-25 ​​Fr venous cannula (LivaNova, London, W2 6LG, United Kingdom) was positioned at the level of the inferior vena cava.
Positioning of the cannulas was guided by transoesophageal echocardiogram.
The tip of the cannula in the superior vena cava laid at superior atriocaval junction, while the tip of the cannula in the inferior vena cava 1 cm beyond the inferior atriocaval junction, in the right atrium.
Two types of pumps for cardiopulmonary bypass have been used: in the first part of the experience a roller pump has been used, subsequently a centrifugal pump has been used instead. In all interventions, before right atriotomy, an active venous drainage (vacuum) was used, the intensity of the venous drainage ranges from -20 to a maximum of -40 mmHg.
In all cases caval veins were not snared nor occluded from the inside and the venous drainage was adjusted to avoid air suction while allowing a satisfactory exposure of the tricuspid valve. Cardiopulmonary bypass was generally conducted in normothermia with the use of normothermic blood cardioplegia. In case of redo procedures or use of endoaortic balloon, crystalloid custodial cardioplegia was used and mild systemic hypothermia was established (32°C).