**3.4 Subclavian/axillary approach**

Subclavian/axillary approach is a useful alternative when transfemoral approach is not feasible. The procedure can be performed under general anesthesia or sedation and local anesthesia. Transsubclavian access is mainly via surgical approach but percutaneous access is possible too [29]. Right subclavian/axillary artery is rarely used for TAVR because of anatomical limitations. The main disadvantage of subclavian access is vascular complications. This artery is frailer than femoral artery. Because of subclavian anatomy, a manual compression might not be feasible. In subclavian access, calcification, stenosis, tortuosity, mammarian and vertebral artery relationship and during surgical cut-down brachial plexus should be evaluated carefully. Minimal subclavian artery diameter should be 5.5 cm. If there is a patent LIMA graft, subclavian access is relatively contraindicated [30].

Transaxillary approach was previously performed by surgical cut-down, nowadays this approach is done completely percutaneously. So that makes this approach first choice alternative way when transfemoral access is not feasible. Axillary artery is outside of thorax so manual compression is possible. The most ideal vascular entry point is between the medial of the pectoralis minor muscle and the outer side of the first rib, and puncture can be performed more easily when the arm is opened to the side [31]. Left axillary is generally preferred because of similarity between femoral artery exit angle. The ideal puncture site is the deltopectoral sulcus. Laterally puncture can cause brachial plexus injury, medially puncture can cause hemo−/pneumothorax and difficulty in compression. Major limitations are nearly same as transsubclavian approach but manual compression and completely percutaneous intervention are advantages.

#### **3.5 Transcarotid approach**

The first successful transcarotid approach was performed by Modine et al. in 2010 [32]. The procedure can be performed by a surgical cut-down or percutaneously. It is a safe procedure but we need to be aware of some special conditions. Carotid artery system should be carefully examined. Stenosis >50% or atheromatous plaques have higher risks for embolization. Contralateral carotid artery, vertebral arteries and posterior cerebral circulation, status of communicant arteries should be examined. Both carotid arteries can be used but the left carotid approach should be preferred because of its angulation with aorta. While performing the procedure, operators should be aware of vagus nerve, laryngeal nerve and respiratory tract.

One of the most important concerns of this procedure is periprocedural stroke. According to a study, comparing transfemoral approach with transcarotid/transsubclavian TAVR, after propensity-score matching, no significant differences in early and long-term outcomes were observed [33].

#### **3.6 Suprasternal approach**

Brachiocephalic artery is a new alternative site for TAVR when transfemoral approach is not feasible. The first suprasternal TAVI procedure was performed in 2015 [34]. This approach does not require sternotomy. Advantage of this access is short distance improving catheter stability. Tortuosity, vessel size, calcification and cervical neck anatomy should be evaluated carefully. Eudailey et al. presented a retrospective study from three centers in the USA of those patients who underwent suprasternal TAVR. A total of 84 patients were included in the study. Thirty-day survival was 98.8% and 0% transischemic attack or stroke was observed [35].

#### **3.7 Transcaval approach**

Because of increased stroke risk during carotid and subclavian approach and alternative sites are not feasible, a new intervention site should be searched. After understanding that caval-aortic truck physiology and detection of retroperitoneal pressure are always higher than those of vena cava inferior, in 2014 Greenbaum et al. performed the first transcaval TAVR [36]. This procedure, is extraordinary as it contains coronary, peripheral, congenital techniques and instruments. Before starting the procedure, aorta, vena cava inferior and adjacent structures should be evaluated carefully. The procedure starts with femoral vein puncture. After arriving at the suitable site, an aortacaval fistula is created with chronic total occlusion guidewire (e.g., Conquest or Astato). After passing the aorta valve, the delivery system is advanced via fistula. After the valve is deployed, fistula is closed with an Amplatzer device. In some cases, adjunctive aortic balloon inflations or covered stent implantation might be necessary. Follow-up CT angiography should be obtained at first and twelfth month after the procedure. This procedure is completely percutaneous and can be used when femoral approach is not feasible.

In conclusion, access for TAVR is a crucial step in patient management. Transfemoral approach is the first choice but, if not feasible, alternative access sites should be discussed in a heart team.
