Anesthesia in the Catheterization Laboratory: Valves and Devices

Hemodynamic Monitoring

By definition, ICCL procedures involve insertion and direct manipulation of catheters and devices within the heart, creating the continuous potential for arrhythmias, perforation, or rupture, causing sudden hemodynamic changes. Monitoring must be continuous and effective. Standard American Society of Anesthesiologists monitors are used for all cases requiring anesthesia, but additional hemodynamic monitors are needed as well. Because of the risk for arrhythmias, external defibrillator pads should be placed on the patient and connected to the defibrillator before starting.

Continuous invasive arterial pressure measurement is the most important hemodynamic parameter to monitor during ICCL procedures. The beat-to-beat blood pressure facilitates the immediate recognition of any significant perturbation, allowing an appropriate reaction to follow in a timely manner. If the patient has significant cardiovascular compromise and needs to be anesthetized, the arterial monitoring should be established before induction. Arterial cannulation for pressure monitoring may be accomplished by the anesthesiologist typically with radial artery cannulation or the cardiologist with a femoral artery sheath. The former allows induction of anesthesia to proceed without delay and has the advantage of being under the control of the anesthesiologist. A radial arterial cannula may be helpful after the procedure if continued monitoring is needed. Femoral artery cannulation may be necessary for access during the procedure and can provide essentially a central aortic pressure, but close communication with the cardiologist is needed to prevent the interruption of monitoring at a crucial time.

Central venous access during ICCL procedures is not as important for monitoring but is needed primarily for the rapid administration of vasoactive drugs to respond to hemodynamic aberrations. Again, this may be accomplished by the anesthesiologist, typically through internal jugular venous cannulation, or the cardiologist with a femoral venous sheath. Internal jugular access has the advantages of being under the control of the anesthesiologist and less dead space, both in the tubing and in the patient, but it may be considered unnecessary if reliable femoral venous access is available. Another important use of central venous access can be rapid administration of fluids in procedures where unexpected blood loss occurs.

If TEE is needed to guide the procedure, it can be used as a monitor as well. In patients for whom general anesthesia is planned, TEE may be used as a monitor even if it is not needed to guide the intervention. Placement of a pulmonary artery catheter may be considered helpful in some cases, such as patients with severe pulmonary hypertension or severe ventricular dysfunction, but these decisions will be influenced by local experience and practice.

When general anesthesia is anticipated for an ICCL procedure, the usual expectation is to emerge and extubate the patient at the end of the case, so the anesthetic plan is tailored to keep this option open whenever possible. On occasion, patients present for an interventional cardiology procedure in such severe respiratory or cardiovascular distress that it is decided to keep them intubated and sedated after the procedure. Patients may need to be kept intubated because of complications occurring during the procedure. Short-acting inhalation and intravenous anesthetics are available, and either technique may be used for ICCL cases, depending on the practitioner’s experience and preference and the patient’s needs.

Transcatheter Aortic Valve Replacement

Aortic valve replacement (AVR) for calcific aortic stenosis remains the most common valvular heart surgery, with 50,000 procedures performed annually in the United States. Although percutaneous valvuloplasty provides temporary relief, valvular stenosis and symptoms typically return within 6 months, making valvular replacement the only definitive therapy. Aortic stenosis prevalence and age-related comorbidities will only increase as the population ages. Health care providers have been developing novel techniques for addressing symptomatic aortic stenosis, including transcatheter prosthetic valve implantation.

Despite the clear benefits of AVR for patients with stenotic valves, open AVR surgery in high-risk patients has an associated perioperative mortality of 4% to 18%, depending on patient comorbidities. Consequently, despite the dismal prognosis of symptomatic aortic stenosis, open-heart surgery is often withheld from high-risk patients. A less invasive management for valvular stenosis might benefit this patient population. Cribier and colleagues first described transcatheter AVR (TAVR) after transcatheter valvuloplasty in 2002. He chose to approach the aortic valve by femoral venous cannulation, transatrial septal puncture, and antegrade deployment through the left ventricular outflow tract by way of the mitral valve. Since then, prosthetic aortic valves have more commonly been deployed retrograde from the aorta by cannulation of the femoral artery and antegrade by puncture of the left ventricular apex by a small left thoracotomy. The PARTNER (Placement of AoRTic TraNscathetER Valve) Trial is a multicenter, randomized study comparing TAVR to medical management (including balloon valvuloplasty) in patients not considered to be surgical candidates and to conventional AVR in high-risk surgical candidates. Published results showed improved survival with TAVR over medical management in patients not considered suitable candidates for conventional AVR and equivalent midterm survival in contrast to AVR in high-risk surgical candidates. Questions have been raised about the findings of these studies and the broad application of TAVR in place of conventional AVR.

In 2011 the FDA approved TAVR in the United States with the Edwards SAPIEN valve for patients with severe aortic stenosis who are not surgical candidates. Ongoing trials are comparing TAVR to conventional AVR in high-risk patients with TAVR using two devices: the Edwards SAPIEN valve (Edwards Lifesciences, Irvine, Calif.) and the Medtronic CoreValve (Medtronic, Minneapolis, Minn.). In 2007, both devices received the quality certificate needed for use in the European Union countries, and it is estimated that over 40,000 devices have been implanted in patients. An expert consensus document addressing TAVR was recently published in a collaborative effort by the American Heart Association, American Society of Echocardiography, European Association for Cardio-Thoracic Surgery, Heart Failure Society of America, Mended Hearts, Society of Cardiovascular Anesthesiologists, Society of Cardiovascular Computed Tomography, and Society for Cardiovascular Magnetic Resonance. It includes an extensive review of the development of TAVR and considerations in evaluating patients for the procedure and the team approach needed to have a successful TAVR program. TAVR is typically performed by a surgeon and an interventional cardiologist in a room that has imaging capabilities and where patients can be anesthetized and undergo surgery, so it is often referred to as a hybrid procedure. This may take place in the ICCL or an operating room, depending on the institution.

The decision to use the transfemoral, transapical, or transaortic approach is based on the size and disease state of the femoral and iliac vessels as assessed with preprocedure imaging. The transfemoral approach is preferred when possible, because it avoids the small thoracotomy needed for the transapical approach. In patients with vessels unsuitable for the transfemoral approach and pathological findings involving the left ventricular apex, such as previous thoracotomy or apical aneurysm, the TAVR may be accomplished through the mid–ascending aorta through a hemisternotomy, referred to as the transaortic approach.

Transfemoral Approach ( Figure 10-1 )

Percutaneous femoral venous access is obtained and a pacing catheter placed in the right ventricle. Small doses of heparin are used to prevent arterial thrombus formation on the arterial catheters. A femoral artery is percutaneously accessed, a 20- to 23-mm balloon-tipped catheter is placed retrograde across the stenotic aortic valve, and a balloon valvuloplasty is performed while rapid ventricular pacing (180 to 200 bpm) effectively halts the circulation for a few seconds ( Figure 10-2 ). Then the deployment sheath (19 to 26 F) is percutaneously placed in a femoral artery, and the prosthetic valve, which is crimped around a balloon-tipped catheter, is advanced over a guidewire through the aorta and across the arch and positioned midway at the level of the aortic valve annulus. Proper positioning of the device is critical; once deployed by expansion of the balloon, it cannot be repositioned. Fluoroscopy or TEE can be used to position the valve, depending on the preference and experience of the operators, but each may provide complementary information. If the device is deployed too far into the ventricle, it may overexpand in the left ventricular outflow tract and be incompetent or not securely seated. If it is deployed too far to the aortic side of the annulus, it can interfere with coronary blood flow or even embolize into the thoracic aorta. The valve is expanded in the native annulus by inflating the balloon while rapid ventricular pacing briefly halts the circulation once again. After deployment, the balloon catheter is withdrawn and the deployment sheath removed using arteriotomy closure sutures previously placed through the percutaneous access site, and the iliac artery is occluded with a balloon catheter advanced from the contralateral femoral artery.

Transapical Approach ( Figure 10-3 )

With the patient anesthetized and intubated, a small, anterolateral thoracotomy is made over the apex of the heart, the pericardium opened, and epicardial pacing wires placed in the myocardium. Lung isolation with a double-lumen endotracheal tube or bronchial blocker has not been necessary. Purse string sutures are placed in the apex of the left ventricle, which is pieced with a hollow needle through which a wire is inserted and passed through the ventricle antegrade across the aortic valve guided by fluoroscopy or TEE. A 16-F sheath is positioned in the left ventricular outflow tract over the wire, and a balloon-tipped catheter is advanced across the aortic valve, with which a balloon valvuloplasty is performed using rapid ventricular pacing. This sheath is exchanged for the larger, device sheath (34 F), through which the prosthesis, crimped on the deployment balloon catheter, is positioned midway at the level of the aortic valve annulus and deployed as with the transfemoral approach. After deployment, the sheath is removed as the apical purse strings are tied down. Rapid ventricular pacing also may be used to help control the blood pressure during this maneuver. Bleeding from the apical wound may require institution of cardiopulmonary bypass with percutaneous femoral cannulation to decompress the left ventricle for control.

The anesthetic considerations of TAVR have been reviewed. Key points are summarized in Figure 10-4 . We have employed hemodynamic monitoring and general anesthesia with endotracheal intubation in all cases, but some centers have used conscious sedation for transfemoral procedures. Most agree that performing TEE during TAVR is an indication for general anesthesia and endotracheal intubation. Most cases require some pressor support and a few positive inotropic agents during the procedure. Double-lumen endotracheal tubes for single-lung ventilation have not been necessary for the transapical cases. A cardiopulmonary bypass machine and a perfusionist team are on standby in the room for transapical cases. We have been able to extubate most of the transfemoral cases and more than half of the transapical cases in the catheter laboratory or operating room at the end of the procedure, and our anesthetic is tailored to allow extubation if all goes well. As experience has accumulated, the procedures are taking less time and having fewer problems.

At my institution, all patients receive TEE monitoring during TAVR. The TEE probe is inserted after endotracheal intubation and removed at the end of the procedure. A comprehensive baseline examination is performed to reconfirm the diagnosis, assess baseline ventricular function, and detect associated valvular lesions, such as mitral and tricuspid regurgitation. Measurements of the aortic valve annulus are made from three-dimensional views to assist size selection of the prosthetic valve. The annulus must be 18 to 21 or 22 to 25 mm in diameter, respectively, for use of the 23- or 26-mm Edwards prosthesis. To prevent obscuring the fluoroscopic image during positioning and inflation of the valvuloplasty balloon, the TEE probe is withdrawn to the level of the aortic arch and then readvanced to assess the results, focusing primarily on the severity of aortic regurgitation. The TEE probe is again withdrawn for positioning and deployment of the prosthesis under fluoroscopic imaging and then advanced to assess the results. As with any major cardiac intervention, we found TEE to be invaluable while monitoring procedural cardiac function.

The deployed device is examined with TEE in short-axis and long-axis views to assess the position of the device within the aortic valve annulus. Deployment too proximal in the left ventricular outflow tract may cause overexpansion of the device and central regurgitation. Distal deployment may cause valve embolization into the aorta or interference with coronary blood flow. Color-flow Doppler assesses atrial regurgitation. TEE can be particularly helpful in differentiating transvalvular aortic regurgitation from paravalvular aortic regurgitation, an important distinction that remains difficult to make using aortic root contrast injection and fluoroscopy. Paravalvular aortic regurgitation may be treated by reinflating the deployment balloon within the prosthesis, further expanding the valve within the annulus. Significant transvalvular aortic regurgitation suggests overexpansion of the prosthesis, which may require deployment of a second prosthetic valve within the first. TEE is also helpful in detecting potential complications such as aortic dissection, myocardial ischemia from coronary artery ostial obstruction or embolization, hemopericardium, and hypovolemia. The application of TEE during TAVR has recently been reviewed, and guidelines have been published.

Transcatheter Aortic Valve Replacement Procedural Complications