**2. Upper mini-sternotomy**

Skin incision runs over the upper half of the sternum and is usually <10 cm long. Sternotomy can be performed with either the standard (our preference) or oscillating saw and is performed in a "J" matter into the right 3rd (Maribor preference) or 4th (Graz preference) intercostal space. The selected intercostal space is determined by the total sternal length, method of myocardial protection delivery (antegrade or combined ante−/retrograde cardioplegia) and surgeon preference. If exposure of the aortic valve is not satisfying, the "J" mini-sternotomy can be modified to a "T" mini-sternotomy or converted to a full median sternotomy. However, care must be taken during sternotomy osteosynthesis when more than two sternal fragments are present to avoid excessive postoperative bleeding or sternal dehiscence. In upper "J" mini-sternotomy, prophylactic division of the right internal thoracic artery (RITA) is not required.

A small-blade retractor is inserted and the pericardium is opened in a longitudinal matter (**Figure 2**) [5]. Two to three stay sutures on both sides are applied and the intrapericardial contents are lifted upwards. Care must be taken not to reduce cardiac preload, which could lead to patient deterioration in the presence of severe aortic valve stenosis.

The cardiopulmonary bypass could be established centrally or peripherally. At our institutions, central cannulation remains the preferred option except in cases of severe ascending aortic calcifications. After systemic heparinization with 300 I.U./kg to achieve an activated clotting time (ACT) > 480 s, the distal ascending aorta is cannulated through two Prolene 3-0 purse-string sutures with pledgets placed in a circular fashion. A double-stage venous cannula is placed through a single Prolene 3-0 purse-string suture either through the right atrial appendage (Graz preference) or in the superior vena cava (Maribor preference). When cannulating the right atrial appendage, the venous cannula could be positioned to the side of the mini-sternotomy wound or under the undivided sternum and beneath the xiphoid (**Figure 3**) [6].

**Figure 2.** *Incision of the pericardium through an upper mini-sternotomy [5].*

**Figure 3.** *Upper mini-sternotomy. Operative field and sternal incision [6].*

The choice of cardioplegia dictates the type of cannulation. Some cardioplegic solutions (for example del Nido extracellular crystalloid cardioplegia) require only antegrade delivery. On the other hand, other solutions (such as blood cardioplegia or St. Thomas extracellular crystalloid cardioplegia) enhance myocardial protection when administered via both ante- and retrograde fashion. In that case, the retrograde cardioplegic cannula is inserted in the coronary sinus through a single Prolene 3-0 U-suture placed between the venous cannula and the inferior vena cava. The antegrade cardioplegic cannula is inserted in the proximal ascending aorta through a single Prolene 3-0 U-suture.

After placing the patient on cardiopulmonary bypass, a left ventricular vent is placed through the right superior pulmonary vein or directly through the aorta. Patients could be safely operated on in normothermia (Maribor preference) or mild hypothermia (34°C) (Graz preference).

The aorta is cross-clamped, cardioplegia is administered and the intrapericardial sac is flushed with cold saline to topically cool the heart. An oblique semicircular incision is made into the ascending aorta and three stay sutures are applied to each commissure (**Figure 4**) [5].

The aortic valve is excised with a 2-mm margin-left on the aortic annulus. After flushing the left ventricular outflow tract (LVOT) and ascending aorta to remove residual calcified particles, an appropriate artificial valve sizer is introduced. Interrupted Ticron 2-0 U-sutures with pledgets are placed through the annulus with pledgets on the ventricular side. Care must be taken on the commissure between the right and a coronary leaflets not to injure the AV node. When an appropriate valve size is chosen, these sutures are placed on the sewing ring and the valve is lowered into the aortic annulus. The sutures are tied either by hand or by novel artificial tying devices (e.g., Cor-Knot). Coronary ostia are carefully inspected to prevent catastrophic consequences (**Figure 5**).

The aortotomy is closed using two Prolene 4-0 running sutures, both starting at the aortotomy edges. The patient is rewarmed if needed and the heart is de-aired mostly through a needle incision in the ascending aorta, just distal to the aortotomy. After removing the aortic cross-clamp, a rhythm check is required. If ventricular fibrillation, external defibrillation is applied. When sinus rhythm occurs, an epicardial temporary pacemaker wire is placed on the right ventricle. This maneuver is facilitated when the heart is actively emptied through the venous cannula and the wire is then pulled out through the 3rd right intercostal space.

Also, during active venous drainage, the external drains are placed. Usually, one retrosternal drain is sufficient placed either through the subxiphoid area or

**Figure 4.** *Superior view of the aortic valve [5].*

### **Figure 5.**

*Probing the coronary ostia (courtesy of Medical University of Graz).*

the 3rd right intercostal space lateral to the RITA. Another viable option is also placement of transpleural drainage tubes.

Weaning from cardiopulmonary bypass follows after complete reperfusion with step-by-step decannulation and oversewing all cannulated spots with Prolene 5-0. Simultaneously with aortic decannulation, protamine is administered in a 1:1 ratio to reverse the effects of heparine. With the pericardium left open, sternal osteosynthesis is performed with one obliquely placed wire between the non-divided lower sternum and the 2nd right intercostal space and one figure-of-eight placed wire around the manubrio-sternal joint. Finally, fascia, subcutaneous tissue and skin are sutured, respectively.
