**4. Techniques of procedure**

After vascular access, a venous access (generally femoral vein) is obtained for pacing during procedure. Nowadays, pacing over the wire technique, which consists of left ventricle (LV) stimulation through the stiff guidewire, is being used. Two arterial accesses are obtained. The main site is for the delivery system and second site is for pigtail. Pigtail is used for reference and aortography. For passing through the calcified aortic valve, generally an Amplatz left 1 (AL1) catheter is used with a soft straight guide wire. When AL1 catheter fails, Amplatz left 2 (AL-2), Judkins right 4 (JR-4) or Amplatz right 1 (AR-1) catheters can be tried in accordance with the anatomy of the ascending aorta and aortic annulus. Using the left anterior oblique (LAO) projection can be useful. After passing the valve, the catheter is advanced to the ventricle and a 300 cm J-tip guidewire is exchanged. A pigtail is advanced over this guidewire. J-tip guidewire is changed to a stiffer guidewire while pigtail is in left ventricle. Safari and Confida are first choices but according to tortuosity stiffer wires, such as Amplatz Super Stiff, Lunderquist Extra Stiff or Backup Maier, can be used. Operators should be aware that the stiff side of the wire must be away from ventricle wall and the position of the wire must be maintained during all manipulations. Patients have severe calcifications and for those who can tolerate rapid pacing, predilatation should be performed with a suitable balloon. The balloon size should not exceed minimal annulus diameter. During full balloon inflation, contrast application via a pigtail catheter can help estimate suitable valve size, interaction with coronaries and probable PVL. In case of severe aortic regurgitation and hemodynamic instability, the valve prosthesis should be ready for insertion before the balloon procedure is completed. Next is valve insertion. Platform should advance, beware of aortic wall interaction. Because of high stent frames, future coronary interventions can be challenging in SEV. With the developing technology, commissural alignment can be achieved using different markers [37]. These markers are different for each valve platform. Fluoroscopic imaging should be followed from the groin to the aortic root. In severe tortuosity and calcific anatomy, detachment may occur in the capsule where the valve is loaded. In such a case, a stiffer wire should be used.

The angle in which the aortic cusps are in the same plane on fluoroscopic imaging is called the coplanar angle (golden angle). Nowadays, a new term is created called the 'Cusp overlap angle'. In this fluoroscopic image, the right and left cusps are superposed and the noncoronary cusp is separated. Compared to other angles, the cusp overlap angle shows more distance between basal annular plane and conduction system. Coplanar angle is the standard plane for many platforms. But SEV platforms use cusp overlap angle because of a high implantation plane for avoiding the need for a permanent pacemaker. According to the noncoronary cusp, >5 mm depth is related to the need for a permanent pacemaker and < 1 mm depth is related to migration. In these situations, SEV platforms allow resheathing.

At the end of the procedure after pulling back the platform, vascular closure is crucial. This is because access site complications are one of the most important mortality and morbidity causes during and postprocedure phase. Dedicated closure devices are used for these issues. But using these devices needs an expert. When closure is done, the patient is taken to the intensive care unit (ICU) for observation.
