Transcatheter transapical aortic valve implantation (2023)

Transapical aortic valve implantation (TAVI) has emerged as a viable alternative to open techniques in high-risk patients. The surgical technique and some important tips and dangers are described.

introduction

Aortic valve replacement (AVR) using open surgical techniques using extracorporeal circulation (CPB) remains the standard of care for symptomatic patients with severe aortic stenosis (AS). Transcatheter aortic valve implantation (TAVI) has become a viable alternative to open techniques in patients for whom open surgical treatment is contraindicated or who are at high risk of perioperative morbidity and mortality. Many reports have demonstrated the safety and efficacy of the transfemoral (TF) and transapical (TA) approaches for TAVI. However, a significant number of patients have poor vascular access due to small vessels or severe peripheral vascular disease and are only eligible for treatment using the TA approach.(1)

Selection and preparation of patients

Currently available scoring systems for patients requiring AVR are flawed in that they are not applicable to a significant subset of these patients. However, they provide a framework for the complex decision-making process for those at high risk for open surgical AVR, including:

1. STS score risk correlates with mortality > 10%.
2. Repeat the operation in an elderly patient in the presence of patent grafts who are at risk of injury due to proximity to the chest wall, based on coronary angiography and computed tomography.
3. However, patient frailty, which is currently subjectively assessed by the surgeon, may also include factors such as the six-minute walk test.
4. History of radiation therapy with associated cardiomyopathy or radiation-induced severe pulmonary disease.
5. The real porcelain aorta ideally determined through three-dimensional analysis of the ascending aorta and aortic arch that vascular control and reconstruction of the aorta would be difficult even with a short period of deep hypothermic circulatory arrest.

Once the patient is at high surgical risk, they should undergo an additional evaluation that includes:

cardiac catheterizationto rule out significant coronary artery disease (CHD). PCI is recommended before TAVI when there are critical CAD that cannot be better addressed by CABG. Care should also be taken during cardiac catheterization to determine the correct C-arm angles for fluoroscopic imaging of the aortic valve. This is typically a right anterior oblique and caudal view or a left anterior oblique and superior view. Additional hemodynamic evaluation of the aortic valve may also be required during this procedure. This is particularly important in patients with left ventricular dysfunction and low-gradient aortic stenosis by echocardiographic evaluation. In addition, it is important to assess the tortuosity of the iliofemoral vessels and to confirm the severity of the vascular disease.

echocardiographyIt is important to confirm the severity of the aortic stenosis, rule out a bicuspid aortic valve (which is a relative contraindication), and determine the aortic ring and left ventricular outflow tract (LVOT) (illustration 1). An accompanying mitral valve disease must also be clarified. Mild to moderate mitral regurgitation (MR) is commonly associated with AS in elderly patients, but does not usually require surgical intervention and is not a contraindication for TAVI. However, severe mitral regurgitation with bulky mitral ring calcification with LVOT has been associated with a poorer mid-term outcome and an increased risk of paravalvular leakage (2).

CT scan of chest, abdomen and pelvisIt must be performed with three-dimensional reconstruction, preferably with contrast if renal function permits. Acquisition is performed with cardiac gating during the thoracic phase to assess the location of the coronary ostium in relation to the aortic ring, which is assumed to be >10 mm to allow safe valve implantation (2). Further evaluation of aortic CT and TEE is also important to delineate morphology and measure aortic root dimensions (Table, Figure 2).

Further examination of the aorta and iliofemoral vessels is performed to confirm poor access for transfemoral delivery and to prepare for rescue cannulation if a switch to extracorporeal circulation (CPB) is required during the TAVI procedure. Additional procedural planning performed at the time of 3-D CT evaluation includes determining the fluoroscopic C-arm position and identifying the relationship of the left ventricular apex to the intercostal spaces. This helps with proper placement of images and sections during the procedure.

Formal lung function studies should also be performed.to assess the severity of a lung disease so often associated with aortic stenosis in high-risk patients. This is particularly important when considering the transapical approach, as these patients must be able to tolerate an anterior thoracotomy incision.

Usage procedure

TAVI is typically performed in a hybrid operating room designed and equipped to accommodate the tools and personnel required to perform open and interventional surgical procedures. TAVI procedures are best performed by a multidisciplinary team that includes a cardiac surgeon, an interventional cardiologist, and a cardiac anesthesiologist experienced in transesophageal echocardiography (TEE). Other team members include a perfusionist, a surgical nurse trained in transcatheter procedures, a circulatory nurse, a radiology or cath lab technician, and a surgical assistant. At least one team member must be trained in preparing and loading the valve jig, which is done at the time of the procedure on the back table using a proprietary crimping jig.

The steps of the procedure are as follows:

1. The 5F Femoral Arterial Sheath is inserted into the femoral artery with the least calcification and tortuosity. This sheath will be used to introduce the pigtail catheter to be used for aortic root injections and for possible arterial cannulation if rescue CPB is required.
2. The 5 or 6F femoral vein sheath is also inserted for insertion of a transvenous pacemaker and as a venous access site for venous cannulation should emergency situations require CPB. Some surgeons prefer placing pericardial wires directly through the thoracotomy incision.
3. At the same time, an anterolateral mini-thoracotomy is performed in the fifth or sixth intercostal space to gain direct access to the apex of the left ventricle. This is best determined by a three-dimensional evaluation of the preoperative CT scan of the chest.
4. A pericardiotomy is performed over the apex of the left ventricle and heparin 100 U/kg is administered to achieve an ACT > 300 seconds.
5. Two concentric purse-string sutures reinforced with pads are placed at the apex of the left ventricle (LV). We prefer to place two additional deep mattress seams at this point.
6. The valve is loaded into the delivery system and checked for proper alignment and seating. For balloon expandable devices, preparation involves sterile crimping of the valve onto the balloon using a special machine designed for the purpose.
7. The LV tip is pierced at the exact center of the purse strings with a standard access needle.
8. The soft access electrode is inserted through the needle into the LV and into the AV, then a 12F sheath is placed at the LV tip to maintain intraventricular access. The Berman pulmonary artery (PA) catheter is then instilled through the LV and through the AV around the aortic arch to the abdominal aorta.
9. A rigid Amplatz wire (260 cm) is then passed through the catheter.
10. The 26F introducer sheath is placed over the Amplatz wire through the tip of the LV.
11. Aortic balloon valvuloplasty is then performed using a 20mm x 5cm balloon during a short episode of rapid ventricular stimulation (RVP).(4)
12. The sapien valve is then advanced through the introducer sheath and positioned through the aortic annulus with 50% of the valve overlying the annulus and 50% under the annulus. Both TEE and aortic root injection are used to confirm valve position and spatial orientation. Ideally, the valve should be aligned with the long axis of the ascending aorta and perpendicular to the aortic ring (Figure 3, 4, 5).

13. The valve is positioned during direct fluoroscopic visualization (Figure 6) with another brief period of rapid ventricular pacing to reduce ejection. Breath is also held during this time to limit movement in the chest cavity and optimize visualization. Clear communication is vital during this short time of the process, so each step of the process is recorded by an individual in a clear standard format.

14. After deployment, both TEE and another angiographic root injection are performed to confirm valve position (Figure 7, 8), rule out paravalvular or central leak and confirm coronary artery patency. Occasionally, the valve may require additional insufflation with supplemental saline.
15. Once the result is satisfactory, the introducer sheath is removed and the purse string sutures tied to ensure hemostasis.
16. Protamine is administered and a left pleural chest tube is inserted.
17. Routine closure of the incision at the access site is performed.

priority card

Routine open heart surgery for AVR.

Covers:

Sheath 5F, 6F und 12F (Terumo Co. Somerset, NJ, USA).

Vaina introductora de 26 F (Edwards Lifesciences, Inc., Irvine, Kalifornien)

Catheter:

Catéter Pigtail 5F (Cordis Corporation, Johnson Johnson, Warren, NJ, EE. UU.).

Berman PA-Catheter

Führer:

.032" x 145 cm Schneider J-Tip Guidewire (Boston Scientific Corporation, Natick, MA, USA).

AMPLATZ Super-Stiff 0.035 inch x 260 cm long x 6 cm long flexible tip (Boston Scientific Corporation, Natick, MA, USA).

Globus:

20mm x 5cm (Z med numbered).

Temporary Pacemaker Leads:

Bipolar pacemaker electrodes (Medtronic)

tips and traps

Apical Approach VI

The apex is preferable to the free wall due to greater convexity and less wall stress. Select an area free of epicardial fat, bite the myocardium at full thickness, and gain needle access at the exact midpoint within the sutures to reduce the likelihood of the enlarged myocardial defect extending beyond the control sutures. Avoid severe high blood pressure, especially when tying sutures. Occasionally, the sutures are tied during a period of rapid ventricular pacing.

When cardiac arrest occurs

Do not hesitate to institute temporary femoral-femoral cardiopulmonary support or proceed with a sternotomy if there is no sign of improvement on initial resuscitation. If chest compressions are required during resuscitation, stent position and valve expansion should be reassessed after resuscitation because the device may be crushed or displaced.

Avoid mechanical complications:

• The most critical part of the procedure is proper positioning. If the valve is too deep in the ventricle (> 50%), there is a risk of embolization into the left ventricle or insufficient closure of the valve. If the valve is too shallow (<50%), there is a risk of aortic embolization, coronary artery occlusion, or excessive paravalvular leakage.
• Avoid aggressive aortic ring overdilation and valve oversizing in patients with a small, heavily calcified aortic ring and aortic root to avoid aortic ring rupture and near certainty of death.
• In patients with a small LV outflow tract, avoid oversized aggressive valve placement too inferior to the aortic annulus to reduce the risk of AV block.
• When advancing a guidewire into the left atrium, the lead should be fully withdrawn from an introducer sheath before attempting repositioning to avoid entanglement between the MV tendons. If the lead forms an unusual angle before entering the aortic valve, this may indicate that the lead is likely to pass through the mitral chordae and become distorted before reaching the aortic valve. We have routinely used the pediatric Bernan PA catheter to cross the valve and bypass the subvalvular mitral apparatus.
• Always leave the guidewire in place and never lose access until the end of the procedure and after confirmation of valve position and stability. If the valve embolizes distally, attach it to the aorta, preferably distal to the origins of the arch vessels to avoid impairing blood flow through the arch vessels.
• If a large calcium load or a heavily calcified cusp is identified, it may be safer to leave a wire in the coronary arteries before performing aortic valvuloplasty to allow for recanalization in the event of embolization (5).
• If a moderate to severe central or paravalvular leak occurs, the balloon can be reinflated to release the leaflets if it is still crumpled, or alternatively, valve-in-valve implantation can be performed.
• In patients with a porcelain aorta, be careful with patients with a very small, calcified sinotubular junction, as this can make balloon inflation difficult and cause the valve and device to backfill with “soft water” into the ventricle.

Postoperative care

Regular maintenance as for conventional AVR with special attention to the following points:

• early extubation.
• Close monitoring of renal function and adequate fluid intake to avoid contrast agent lesions in the kidney.
• Temporary pacing leads are maintained for additional days in patients at risk of late atrioventricular (AV) conduction block.

complications

Intraoperative complications:

• Apical injury and bleeding.
• Heart attack
• Rupture of the aortic root or annulus
• heart block and arrhythmia
• ischemia or myocardial infarction
• Lesion of the mitral valve apparatus and worsening of mitral regurgitation
• Valve migration and embolization
• Coronary Ostialobstruktion
• paravalvular or central leak

Postoperative Complications:

• Bleeding requiring re-examination of the chest
• acute renal failure
• Thromboembolic Events and Cerebrovascular Events
• left ventricular pseudoaneurysm

Results

The PARTNER study is the only randomized controlled TAVI study to date. Judgment has two arms; the first compares drug therapy to transfemoral TAVI in patients who are not candidates for open surgery. The second arm compares TAVI (either transfemoral or transapical) to open surgical therapy in patients who are at very high risk for open surgical treatment. The study has just finished enrolling patients and the results are not yet available.

There are a number of non-randomized studies that have shown a 30-day mortality of 10% with a survival rate of 75% at one year (6), which is comparable to the results of open surgery (7).

references

1. Kurra V, Schönhagen P, Roselli EE, Kapadia SR, Tuzcu EM, Greenberg R, et al. Prevalence of significant peripheral arterial disease in patients being evaluated for percutaneous aortic valve insertion: preprocedural assessment using multidetector computed tomography. J Thorac Cardiovascular Surg. 2009 May;137(5):1258-64.
2. Masson JB, Kovac J, Schuler G, Yen J, Cheung A, Kapadia S, et al. Transcatheter aortic valve implantation: review of the type, management, and avoidance of complications of the procedure. JACC Cardiovascular Interv. 2009;2(9):811-20.
3. Akhtar M, Tuzcu EM, Kapadia SR, Svensson LG, Greenberg RK, Roselli EE, et al. Aortic root morphology in patients undergoing percutaneous aortic valve replacement: evidence of aortic root remodeling. J Thorac Cardiovascular Surg. April 2009; 137(4):950-6. Epub 2009 February 23.
4. Moon MC, Dowdall JF, Roselli EE The use of right ventricular pacing to facilitate stent-grafting deployment in the distal aortic arch. J Vasc Surg. 2008 Mar;47(3):629-31.
5. Kapadia SR, Svensson L, Tuzcu EM. Successful percutaneous management of left main stem occlusion during percutaneous aortic valve replacement. Cardiovascular Catheter Interv. 2009;1; 73: 966-72.
6. Svensson LG, Dewey T, Kapadia S, Roselli EE, Stewart A, Williams M, et al. United States Feasibility Study of Transcatheter Aortic Valve Insertion with Left Ventricular Apex Stent.Ann Thorac Surg.2008;86:46–54.
7. Walther T, Schuler G, Borger MA, Kempfert J, Seeburger J, Rückert Y, et al. Transapical aortic valve implantation in 100 consecutive patients: comparison with conventional propensity-matched aortic valve replacement. Eur Heart J. 16 Mar 2010. [Epub ahead of print]