Patients with severe aortic stenosis may instead undergo AVR with a specially made bioprosthetic valve, which is inserted via a catheter, thus obviating the need for re-operative sternotomy. (Image source: Thinkstock)
Patients with severe aortic stenosis may instead undergo AVR with a specially made bioprosthetic valve, which is inserted via a catheter, thus obviating the need for re-operative sternotomy. (Image source: Thinkstock)

Patients with severe aortic stenosis (AS) may be old, frail, have significant comorbidities, and have by definition have highly compromised ventricular function. They may also have had previous cardiac surgery. These risk factors may place the patient at inordinate risk from conventional aortic valve replacement (AVR). Transcatheter aortic valve replacement (TAVR) is potentially far less invasive, and hence garnering attention for patients with a life expectancy greater than one yeara. The procedure itself and anesthetic considerations are summarized by Andrew A. Klein, Department of Anaesthesia, Papworth Hospital, Cambridge, The United Kingdom, and colleagues from the United States and Germany in this month’s issue of Anesthesia & Analgesia in the article titled “Controversies and Complications in the Perioperative Management of Transcatheter Aortic Valve Replacement.”

Patients with severe aortic stenosis may undergo TAVR with a specially made bioprosthetic valve, which is inserted via a catheter, thus obviating the need for sternotomy. The TAVR is inserted retrograde if the catheter is inside the femoral artery (TF, transfemoral approach), or antegrade if the catheter is inserted directly into the cardiac apex (TA, transaortic approach). The TAVR valve is positioned across the aortic annulus and deployed via balloon inflation (Edwards SAPIEN) during short periods of rapid ventricular pacing, or self-deployed (CoreValve).

The TAVR procedures is performed in the angiographic suite or the cardiac surgical operating room. The procedure room is modified to allow for multimodal imaging (fluoroscopy and transesophageal echocardiography), invasive hemodynamic support, and potential conversion to open sternotomy and surgical AVR with cardiopulmonary bypass. A TAVR procedure should be performed in a heart valve center by specially trained cardiologists, surgeons, and anesthesiologists.

The scope of this multidisciplinary approach is multifold: patient selection (jointly performed by a surgeon and a cardiologist) and preoperative optimization. Critical to the procedure ismatching of the patient’s aortic annulus to the correct TAVR size. The prostheses come in two or three sizes. CT imaging or three-dimensional transesophageal echocardiography are the preferred imaging modalities to determine the correct size.

The anesthetic for a TAVR procedure should be focused on the patient’s comorbidities as well as accommodate the procedural steps. A general anesthetic allows the use of transesophageal echocardiography in an immobile patient with a secured airway. On the other hand, others may opt for a monitored anesthesia care technique if the procedure is quick and transthoracic echocardiographic imaging is performed.

The most frequent complications in a TAVR procedure are due to vascular access. These may decrease in the future with the advent of introducers of smaller diameter, which can be inserted in the small, fragile, or diseased femoral arteries of elderly patients. Less frequently encountered complications are cardiac or aortic injuries. During each TAVR procedure, a “stormy” hemodynamic period should be anticipated due to abrupt flow cessation during the periods of rapid ventricular pacing. The procedure is successful if the TAVR bioprosthesis does not have more than mild paraprosthetic aortic regurgitation, as verified by real-time transesophageal echocardiography.

Demand for the procedure is increasing. Though it is now used for patients who are old and frail, or who have significant comorbidities, more research will show whether the procedure is appropriate for younger individuals with fewer comorbidities. It will likely add to our growing list of routine procedures that require our services but are performed outside the operating room.