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TAVR alternate access sites
Background
The transfemoral approach remains the first-line access choice for transcatheter aortic valve replacement (TAVR). Initially up to a third of patients were unsuitable for the transfemoral approach, although this has decreased to less than 10% with contemporary valve designs. In our experience, of 1337 cases (TF 1220, alternative access 117), we used alternative access in just 9% of cases.
Common contraindications to the transfemoral approach include small femoral arterial size, excess calcification, tortuous arteries, and atherosclerotic disease of the aorta.
When the transfemoral approach is not feasible, an alternative method of arterial access is needed. Any artery of adequate size can suffice for access, and this includes the left ventricular (LV) apex, ascending aorta, carotid artery, axillary artery, iliac artery, and atrial septum.
There is a paucity of comparative literature on alternative access sites, and choice primarily depends on physician and institutional preference. There is no randomized study comparing different types of alternative access.
It is important to note that patients undergoing TAVR through alternative access have more comorbidities and higher rates of coronary and peripheral vascular disease than those suitable for a transfemoral approach. Unadjusted outcomes suggest higher mortality and complications in the nontransfemoral group, but after propensity matching for these comorbidities, outcomes are similar to a transfemoral approach. As for transfemoral access, it is important to follow a standardized protocol and use a safety checklist ( Fig. 11.1 ).
Transapical
Advantages, disadvantages, and contraindications
Unlike the transfemoral approach, transapical access requires general anesthesia and is considered a more invasive approach. In our experience, the only absolute contraindication to this access is LV apical thrombus. We have successfully performed transapical access in the presence of severely reduced ejection fraction, porcelain aorta, mediastinal radiation, and breast implants.
Planning
For planning of transapical access, the apex in relation to the chest wall is studied on computed tomography (CT) scan.
Technique
The position of the apex is located using fluoroscopy, and the site is marked on the skin ( Fig. 11.2 ). The patient is prepped and draped in the supine position. A left anterior thoracotomy incision is made in the inframammary crease, centered on the LV apex mark. The appropriate rib overlying the apex is removed in a subperiosteal fashion. The apical fat pad is removed, and the pericardium is incised to expose the bare area of the LV apex. Both a soft tissue and rigid retractor are helpful in providing exposure.
Small-caliber sheaths are used to secure percutaneous access in the femoral or radial artery for insertion of the pigtail catheter in the aortic root and venous access for temporary pacing. Heparin is administered, with a target activated clotting time (ACT) greater than 250 seconds. Lidocaine is also administered in preparation for the LV puncture. A balloon-tipped pacing lead is positioned in the right ventricular apex under fluoroscopic guidance. A standard root angiogram is performed to confirm the prescribed orthogonal angle (“working view”), with the three aortic valve sinuses lined up as per the methods for transfemoral TAVR.
The systemic blood pressure is lowered to 100 mmHg and kept around that level for the remainder of the invasive part of the procedure, reducing bleeding and allowing hemostasis of the ventricular puncture site. An anatomically appropriate position for the puncture site can be confirmed by palpating the proposed site of puncture with a finger and observing the area of indentation on transesophageal echocardiography.
Suture placement is one of the most critical aspects of a successful procedure. Full-thickness, horizontal mattress sutures are placed in the bare area of the LV apex, well away from the left anterior descending coronary artery ( Fig. 11.3 ). We use pledgetted 2-0 Prolene sutures (Ethicon, Somerville, NJ) on an MH needle.
The ventricle is punctured and a J-wire positioned across the aortic valve into the ascending aorta. A 7F sheath is then inserted across the aortic valve. A JR4 catheter is used to position the J-wire across the aortic arch and down into the lower descending thoracic aorta. The J-wire is then exchanged for a stiff wire. The JR4 catheter and 7F sheath are then removed. The Edwards transapical sheath (18F to 21F) is inserted under fluoroscopic guidance. Balloon valvuloplasty is generally not performed.
The balloon-expandable valve is positioned across the patient’s native aortic valve. Under rapid ventricular pacing, a root angiogram is completed. The position of the valve is fine-tuned, and then the valve is deployed in a slow and controlled manner. During deployment, the valve tends to move ventricularly, and this must be countered with gentle forward pressure on the delivery device ( Fig. 11.4 ).
After deployment, the delivery device is pulled back into the sheath. Valve position and function are assessed with intraoperative transesophageal echocardiography. Providing the valve position and function are satisfactory, the delivery device, wire, and sheath are removed and the sutures secured.
The pacing lead and pigtail catheter are removed, and protamine is given. The femoral artery sheath is removed and the site secured with pressure or a closure device. Separate drains are placed in the pericardial and pleural spaces. The drains are brought out through incisions inferior to the wound. The pericardium is loosely reapproximated. Because a portion of the rib was resected, the intercostal space is not brought together. The thoracotomy incision is closed by approximating the cut edges of the pectoralis muscle.
The pericardial drain is left in place until drainage is less than 30 cc in 24 hours. The pleural drain can usually be removed when drainage is less than 300 cc in 24 hours.
Approach-specific surgical pitfalls and complications
Patients are extubated in the intensive care unit. The systolic blood pressure is carefully maintained at less than 140 mmHg throughout the postoperative hospital stay.
Transaortic
Advantages, disadvantages, and contraindications
Similar to the transapical approach, general anesthesia is required. The image intensifier sits right over the aortic puncture site and may get in the way during the procedure and increase radiation exposure to the operators.
Contraindications to this access include significant calcification at the proposed aortic puncture site and a short distance (e.g., less than 6 cm) from the proposed puncture site to the aortic valve annulus. This is because the introducer sheath requires a minimum length within the body for successful valve insertion. Previous sternotomy is not a contraindication to transaortic access.
Planning
The position of the aorta in relation to the sternum is determined on CT scan ( Fig. 11.5 ). The key anatomic landmark is the location of the mid-ascending aorta in relation to a perpendicular line drawn from the right edge of the sternum ( Fig. 11.6 ). On whichever side of that line the majority of the aorta lies determines access: that is, >50% of the aorta to the right of the line would be best approached through a thoracotomy, whereas >50% to the left would be best approached through a sternotomy.
Access is dependent on the underlying anatomy, but is generally through either a limited right-sided second interspace thoracotomy or upper sternal split/J-type sternotomy.
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