Structural Heart Disease Procedures

Balloon-Expandable Transcatheter Aortic Valve Implantation

The SAPIEN 3 transcatheter heart valve (THV) (Edwards Lifesciences LLC, Irvine, CA) is a trileaflet, bovine pericardium intraannular valve mounted into a radiopaque, cobalt-chromium alloy frame. The 29-mm valve is not currently available in the latest model, the SAPIEN 3 Ultra. An internal polyethylene terephthalate skirt at the inflow portion of the valve is larger than previous versions. A second external skirt wrapped around the stent frame is also taller than previous iterations and helps to seal the valve in order to reduce paravalvular regurgitation (PVR). The overall stent frame profile is low, which allows for less complicated coronary access after TAVI.

The SAPIEN 3 Ultra THV is mounted to the delivery system, which consists of a balloon catheter and a separate flexible catheter to aid in positioning. The valve is then prepared with a crimper that reduces the overall diameter of the system, allowing insertion into a 14- or 16-Fr expandable vascular access sheath, depending on valve size. This sheath expands transiently to allow passage of the valve and can be used in patients with a vessel diameter ≥5.5 or 6 mm. This represents a significant improvement from previous generations and enables more transfemoral and percutaneous access. Valve expansion occurs by balloon inflation. Following valve expansion, the balloon is deflated and removed from within the stent frame. The SAPIEN 3 THV is not repositionable once expanded; however, deployment is generally straightforward.

Self-Expanding Transcatheter Aortic Valve Implantation

The CoreValve Evolut R System (Medtronic, Minneapolis, MN) is a trileaflet porcine pericardium valve sutured on a radiopaque nitinol alloy frame made of nickel and titanium. Improving on a previous design, the Evolut Pro and Evolut Pro+ systems have an additional external tissue wrap to reduce PVR. The valve is engineered to be supraannular to achieve a higher effective orifice area and lower pressure gradients. An increased frame height compared to the balloon-expandable valve may make future coronary access more challenging.

A proprietary loading system compresses the bioprosthesis into a flexible, nonsteerable external delivery catheter. This catheter system uses a true 14-, 16-, or 18-Fr inline sheath, depending on valve size. Because the sheath retains its outer diameter and does not expand, it can be used with access vessel diameters as small as 5.0, 5.5, or 6.0 mm, respectively. The catheter maintains the valve in a compressed position until it is positioned across the native annulus. The catheter is then retracted allowing the valve to self-expand and conform to the native annulus with a consistent radial force. If the position is suboptimal, the delivery catheter can recapture and reposition the valve after partial deployment of up to 80%.

The Portico TAVI System (Abbott Structural Heart, Santa Clara, CA) is a fully resheathable, repositionable, and retrievable self-expanding valve. Receiving FDA approval in September 2021, it is currently used in a minority of cases.

Preprocedural Planning

All patients with known or suspected AS should be evaluated by a heart team capable of performing both TAVI and SAVR. A thorough history and physical examination should be performed to determine symptoms and comorbid disease. An assessment of functional status and frailty should be completed. A baseline electrocardiogram should be reviewed to evaluate the rhythm and identify conduction disturbances. A comprehensive echocardiogram with Doppler interrogation should be performed to determine severity of disease, baseline biventricular function, and to detect concurrent valve disease. Transthoracic echocardiography (TTE) is most frequently used.

Once severe AS is confirmed, multidetector computed tomography (MDCT) should be performed and serves multiple purposes. First, it provides necessary information about arterial caliber, tortuosity, and calcium burden that determines suitability for femoral or alternative access sites. Second, MDCT may be able to rule out concurrent coronary artery disease in some patients and thus eliminate the need for cardiac catheterization. Third, MDCT best defines the anatomy of the aortic root including the coronary ostia, aortic annulus, and LV outflow tract. MDCT is the gold standard for annular measurements used for valve sizing. While three-dimensional (3D) transesophageal echocardiography (TEE) may provide similar measurements when MDCT data are not available, it cannot assess coronary artery or access site anatomy. Whatever studies are to be performed, they should be completed prior to the procedure date to allow proper planning.

When all information is available the heart team should formulate a plan for intervention based on disease, risk assessment, comorbidities, and frailty. Options include balloon aortic valvuloplasty (BAV), TAVI, or SAVR. When TAVI is considered, both type and size of valve should be determined as well as the need for necessary concurrent procedures including those for cerebral embolic or coronary protection. The heart team recommendation should then be discussed with the patient and their primary physician before a final decision is made, as part of a shared decision-making approach.

Procedural Description

In 2019, 95.3% of TAVI performed in the United States was done with femoral arterial access, although transapical, transaortic, subclavian, transcarotid, and transcaval approaches were also used. For the transfemoral approach, bilateral access is required. First, a 7-Fr introducer sheath is placed on the nontreatment side. Through this, a 5-Fr pigtail catheter is guided into the noncoronary cusp of the aortic root under fluoroscopy. Blood pressure can be monitored by transducing the sheath or catheter. Next, treatment side access is gained with a 5-Fr sheath. Heparin is administered to a target activated clotting time of 250 seconds and vascular site closure devices are prepositioned to prepare for the delivery sheath.

Rapid ventricular pacing is required for balloon-expandable systems but may also assist BAV and deployment of self-expanding systems. Pacing may also be necessary in the setting of new-onset conduction disturbances and therefore should be obtained for all TAVI. Temporary right ventricular (RV) pacing can be achieved via the right internal jugular vein or femoral vein and maintained postoperatively. Temporary LV pacing has also been described.

Once access is achieved, the aortic valve is crossed with an exchange-length wire via the treatment side sheath. Ventricular ectopy may occur. Predeployment BAV may be performed when indicated. The TAVI delivery system is then placed over the wire and across the valve. During deployment, diminished cardiac output should be anticipated transiently; however, more serious complications such as coronary obstruction, ventricular wire perforation, or vascular injury must be ruled out if hypotension persists. Appropriate valve position and function after deployment is confirmed with fluoroscopy and echocardiography. Post-deployment BAV may be performed to correct PVR. The wire and delivery system are withdrawn, and protamine is administered. The arteriotomy is then closed by tightening the previously placed closure devices. Peripheral angiography can be used to rule out vascular injury.

Anesthetic Management

Contemporary TAVI can be performed under monitored anesthesia care (MAC) or general anesthesia (GA). As of 2019, 64.1% of percutaneous transfemoral TAVI in the United States was performed under sedation ( Fig. 23.3 ). The use of less invasive access, as well as experience with the procedure have led to an increasing use of MAC and an overall less invasive anesthetic management, including fewer invasive lines and monitors and faster extubation when an endotracheal tube is used. Continuous blood pressure monitoring can be obtained by placement of a radial arterial catheter or by transducing the procedural access site. Central venous access for fluid administration may also be shared from the procedural field. Pulmonary artery (PA) catheters are no longer frequently used.

In TAVI, indications for GA are similar to other procedures and include a high risk of aspiration, obstructive sleep apnea, and patient preference. The incidence of conversion to GA in current practice is between 0.6% and 5.9% and may occur due to procedural complications or poor tolerance of sedation. ^, Procedure-specific indications for GA in TAVI include the use of alternative access sites or institutional practice. The use of TEE may also encourage but does not require the use of GA. When MAC is selected, the use of various short-acting infusions has been described, including dexmedetomidine, propofol, and remifentanil. These medications and volatile anesthetics have also been used for the maintenance of GA. Inotropic and vasoconstrictive medications should be available but are not frequently required. Sedation under the direction of the proceduralist and without an anesthesiologist has been described.

While improved procedural outcomes have facilitated a transition in anesthetic technique, there is evidence suggesting the choice of anesthesia care itself may be associated with better outcomes. A study comparing conscious sedation and GA in 10,997 patients undergoing transfemoral TAVI found a decrease in in-hospital mortality, 30-day mortality, a composite endpoint of stroke and mortality, and hospital length of stay associated with avoidance of GA.

Procedural Echocardiography

TAVI is typically performed using either TTE or TEE, although it is also performed with fluoroscopy as the sole intraprocedural imaging modality. As the more invasive approach, TEE should generally be reserved for when GA is used, or when a clinical question remains after other imaging studies. Interventional echocardiography for TAVI can be performed by an anesthesiologist, a cardiologist, or an echocardiography technician when reviewed by the procedural team.

A baseline echocardiogram with spectral Doppler should be performed to confirm the presence of AS, quantify biventricular function, and detect any pericardial effusion. When using TTE, it is particularly important to identify the windows that best visualize cardiac structures preprocedurally in order to expedite subsequent imaging. The goals of post-deployment echocardiography are to evaluate valve seal, peak velocity, shape, and to identify any complications. A well-functioning valve should be without significant transvalvular or PVR with color-Doppler interrogation on short and long axis. Spectral Doppler measured peak systolic velocity should be <2.0 m/s with an early peaking morphology. The valve should appear circular on short axis and only a few millimeters below the native annulus on long axis. Self-expanding valves should be evaluated after partial deployment and findings may indicate the need to recapture or reposition before final release. Both valve types should be expeditiously evaluated post deployment in the presence of hemodynamic instability. Valve migration, new wall motion abnormalities, PVR, aortic injury, and pericardial effusion can all be diagnosed with echocardiography. Identification of these findings requires a discussion with the procedural team and may necessitate balloon post dilation, placement of a second valve, pericardiocentesis or sternotomy.

Postoperative Care

Routine TAVI completed without complication no longer requires postoperative management in the intensive care unit (ICU). Conduction disturbances remain a common complication, with 8.3% of TAVI requiring permanent pacemaker implantation during index hospitalization. Conduction disturbances most frequently occur intraprocedurally; however, delayed-onset complete heart block may manifest hours or days after TAVI. Telemetry monitoring is required for all patients and an electrocardiogram should be evaluated when changes from baseline are suspected. Access site bleeding or hematoma can occur, and patients should remain supine and limit hip flexion for a minimum of 2 to 4 hours. After this period, early ambulation is encouraged as enhanced recovery protocols allow for early discharge as soon as postoperative day 1. In 2019, the median US length of stay was 2 days. While anticoagulation protocols vary, evidence from a randomized controlled trial found that compared to aspirin and clopidogrel, patients receiving aspirin monotherapy had lower rates of bleeding without an increase in thromboembolic events.

Procedural Description

Quantification of AS should be performed before BAV and repeated post procedure using invasive pressure monitoring or TTE. Percutaneous femoral arterial access is established with an 8 to 12 Fr catheter, and a wire is placed retrograde into the LV. A balloon catheter, sized based on annular dimensions, is threaded over the wire across the annulus. The balloon is then inflated up to 6 atm for approximately 5 seconds, then deflated. Repeat inflations may be required. This results in fracture of calcium deposits within valve leaflets, separation of commissural fusion, and annular stretching. Rapid ventricular pacing may be used to prevent systolic ejection of the inflated balloon. Percutaneous closure devices may be used at the access site.

Anesthetic Management

MAC may be used in routine cases and skin infiltration with local anesthetic should provide sufficient analgesia. The anesthesiologist should be prepared to manage transient hemodynamic instability related to diminished cardiac output and coronary perfusion during balloon inflation. Transient or permanent conduction disturbances may occur and can be managed with transcutaneous or transvenous pacing. Access site vascular complications may result in bleeding or the need for surgical cutdown. Other complications include new-onset aortic regurgitation, aortic dissection, and annular rupture.

Preprocedural Planning

Before proceeding with TEER, a complete history and physical examination must be performed to evaluate suitability for cardiac surgery. Next, an anatomic assessment of the mitral valve is necessary to determine whether TEER is feasible. Preprocedural TTE can determine the severity of MR and identify concomitant valvular disease that may influence the decision perform surgery. Treatment of severe AS with TAVI first should also be considered, as this may contribute to both symptoms and severity of MR.

Preoperative 3D TEE should be performed for a more detailed understanding of valve pathology. Favorable anatomy for degenerative MR consists of an A2/P2 prolapse or flail with a gap <10 mm and width <15 mm ( Table 23.2 ). ^, For functional MR, there should be normal leaflet thickness and a coaptation depth <11 mm. With either pathology, the mean gradient should be ≤4 mm Hg with a grasping zone >10 mm. Unfavorable valvular features include multiple jets, the presence of clefts near leaflet prolapse, leaflet restriction, previous annuloplasty ring, Barlow’s disease or severe mitral annular calcification. Other unfavorable anatomic findings include the presence of a thickened interatrial septum and hypertrophic cardiomyopathy with systolic anterior motion of the mitral valve. Up to one-third of patients screened are declined due to unfavorable anatomy.

Procedural Description

A 5-Fr femoral sheath is first placed, preferably in the right femoral vein. This sheath is then exchanged for a device-specific dilator, which is positioned into the right atrium (RA). Through this, a needle is then advanced to the atrial septum and used for transseptal puncture under fluoroscopic and TEE guidance. The site of the puncture should be superior and posterior in the fossa ovalis to optimize maneuverability of the delivery system. This puncture should be 4 cm above the level of the anterior leaflet, with more height needed for medial lesions. Hemodynamic tracings together with TEE confirm successful puncture into the LA. The device-specific sheath is then advanced into the LA and heparin is administered to achieve a target activated clotting time of 250 seconds. An exchange-length guidewire is inserted, the device sheath is removed, and the device catheter and delivery system is advanced into the LA and oriented perpendicular to the coaptation line at the desired valve scallops. The implant arms are then opened and the delivery system is advanced across the mitral valve. The catheter is retracted slowly and the leaflets are visualized entering the arms of the implant, which are then closed. TEE is used to confirm leaflet capture, adequate tissue bridge, and to assess the degree of residual MR. The arms can be reopened and repositioned prior to definitive release if the grasp is unsatisfactory. A second implant may be placed after assessment of mitral valve gradient. The delivery system is then retracted, and hemostasis of the femoral vein is achieved.

Anesthetic Management

Anesthetic management for patients undergoing TEER routinely involves GA with an endotracheal tube to facilitate a comprehensive TEE examination. The use of MAC is less common but has been described. It should be recognized that the use of GA may lead to the underestimation of MR. While large hemodynamic changes are not expected during a routine uneventful case, invasive arterial monitoring is usually the standard of care. Patients who are New York Heart Association (NYHA) class 3 and above with heart failure symptomatology will need careful preoperative optimization, as well as the use of inotropes and vasopressors administered either through PA catheters placed in the jugular vein or via femoral access placed by the proceduralist. The anesthesiologist should be prepared for potential complications including intracardiac perforation, cardiac arrhythmia, and air embolism via the delivery catheter. Significant reduction of MR will acutely increase LV afterload. Peripheral venous injury is typically easier to manage in venous structures compared to arterial injury. Fluid restriction is preferred in patients with decompensated heart failure. Patients are typically extubated at the end of the procedure.

Procedural Echocardiography

Table 23.3 follows the key aspects of TEE guidance for TEER with MitraClip. Successful procedural guidance begins a comprehensive baseline intraoperative TEE to confirm previous defined anatomic features including the location and number of regurgitant jets. Transseptal puncture is guided using a modified midesophageal aortic valve short-axis view and midesophageal bicaval view, allowing for determination of the anterior-posterior and superior-inferior orientation. Simultaneous biplane imaging can be used. Tenting of the septum should be visualized prior to puncture. Entry of the guide catheter should be visualized. Three-dimensional en face visualization of the mitral valve, known as the surgeon’s view, should be used to position the guide catheter at the location of maximal MR before the LV is entered. The midesophageal mitral commissural and midesophageal long-axis view should be used to confirm proper implant arm orientation. A simultaneous biplane image of these views can be used to confirm grasp of the leaflets. Assessment of mitral valve gradient and residual MR should then occur. Fig. 23.6 shows an illustrative case of severe secondary MR successfully treated with implantation of a PASCAL implant.

Postoperative Care

TEER patients should be monitored in a telemetry unit for immediate postoperative complications relating to vascular injury, arrhythmia, and effusion. Patients are at high risk for postoperative delirium due to advanced age. However, compared to TAVI, TEER postoperative recovery may be more straightforward owing fewer conduction disturbances, and the use of venous access. Postoperative ICU admission is rare but is seen in heart failure patients and those with associated comorbidities that preclude rapid extubation. Research using 2016 data from a national US database found 61% were discharged in 2 days or less. The readmission rate in this cohort was 10.1%, compared to 13.5% overall. Fifty-six percent of readmissions were of a cardiovascular etiology. Same-day discharge has been described but is uncommon. There are no formal imaging recommendations; however, TTE may be performed at 30 days or sooner if a complication is suspected.