TAVR Procedure guide

# Overview
During the past 50 years, surgical aortic valve replacement (SAVR) was the standard of care for patients with severe AS. Global aging has raised concerns about safety and possibility of surgical procedure in old patients with associated co-morbidities. Transcatheter aortic valve replacement (TAVR) created a new era of safety for this population and enabled physicians to replace the  stenotic valve with more certainty. 
Preoperation evaluation, selecting the appropriate imaging modality, issues in TAVR procedure and patient follow up are the areas of more focused importance.
We will describe these factors based on the recent expert consensus for TAVR procedure.

# Definition
The most important step is to define the severity of AS and appropriate patient that need TAVR.
Severe symptomatic (Stage D) AS is considered as TAVR candidate.
Abbreviations:
P: mean gradient, Vmax: maximum aortic velocity, AVA: aortic valve area. AS: aortic stenosis, AR: aortic regurgitation.

# TAVR Pathway outline
Abbreviations:
CV: Cardiovascular, AVR: aortic valve replacement, AS: aortic stenosis, MR: Mitral regurgitation, AR: Aortic regurgitation, PAP: Pulmonary artery pressure, RV: right ventricle, CTA: CT angiography, PA: Pulmonary artery, TEE: Trans Esophageal Echocardiography, TTE: Trans Thoracic Echocardiography

## Care Providing Team

## Clinical Evaluation

## Cardio-vascular Imaging

# Heart Valve Team
Patients with severe AS should be evaluated by a multidisciplinary Heart Valve Team when intervention is considered.
Team members include:
- Cardiology Valve Expert
- Cardiovascular Imaging Expert(s)
- Interventional Cardiologist
- Cardio-Thoracic Surgeon
- Cardiovascular Anesthesiologist
- Valve Clinic Care Coordinators
Their specific tasks are:
- Review the patient's medical condition and the severity of the valve abnormality
- Determine which interventions are indicated, technically feasible, and reasonable
- Discuss benefits and risks of these interventions with the patient and family, keeping in mind their values and preferences.

# Initial Assessment

## Functional Assessment
Abbreviations:
BMI: body mass index; CV: cardiovascular; MMSE: mini mental state examination; MNA: mini nutritional assessment.

### Frailty
- Evaluation for frailty, physical function and independence in the activities of daily living (ADL) such as, feeding, bathing, toileting and transferring).
- Evaluation should be start with screening for independence, cognition and slow walking speed (gait speed, 3 timed trials over a 5 meter distance).
- Those with gait speed over 0.83 m/s, preserved cognition and independence are likely not frail.

### Physical functioning
To assess the physical functioning, the 6 minute walk test should be done. It is possible to perform this test in outpatient setting.

### Cognitive Functioning
The Mini Mental Status Examination (MMSE) is utilized to assess the cognitive status and scores less than 24 are considered as abnormal. Also, evaluation for depression must be done by using a validated tool such as, the Center for Epidemiologic Studies Depression Scale.

### Futility
Those patients with <1 year life expectancy and who has a chance of survival with benefit of <25% at 2 years. 
Survival with benefit means, survival with improvement by at least 1 New York Heart Association class in heart failure or by at least 1 Canadian Cardiovascular Society class angina symptoms, improvement in quality of life or improvement in life expectancy.

# Risk Assessment
Underlying risk for SAVR is basic component to consider patient for TAVR. This risk assessment is based on several components that include:
- The Society of Thoracic Surgeons Predicted Risk of Mortality (STS-PROM) score. To calculate this score please click here.
- Frailty
- Main organ system dysfunction
- Procedure-specific impediments
 Examples of major organ system compromise:
- Cardiac: severe LV systolic or diastolic dysfunction or RV dysfunction, fixed pulmonary hypertension
- CKD stage 3 or worse
- Pulmonary dysfunction with FEV1 <50% or DLCO <50% of predicted
- CNS dysfunction (dementia, Alzheimers disease, Parkinsons disease, CVA with persistent physical limitation)
- GI dysfunction: Crohns disease, ulcerative colitis, nutritional impairment, or serum albumin <3.0
- Cancer: active malignancy
- Liver: any history of cirrhosis, variceal bleeding, or elevated INR in the absence of VKA therapy.
 Examples: tracheostomy present, heavily calcified ascending aorta, chest malformation, arterial coronary graft adherent to posterior chest wall, or radiation damage.

## Integrated Benefit-risk of TAVR and Shared Decision-making

# Imaging for TAVR

## General Principles and Technical Considerations
- Transthoracic Echocardiography (TTE) is the best initial imaging modality for evaluating AS severity. Although, multimodality imaging is needed for preprocedural planning and intraoperative decision making given the complex 3D anatomy of the aortic valve, sinuses, and annulus.
- Multi-Detector CT (MDCT) is a core element of the standard imaging pathway for the preprocedural planning of TAVR.
- In patients being evaluated for TAVR, MDCT systems with at least 64 detectors and a spatial resolution of 0.5 to 0.6 mm are recommended.
- Evaluation of kidney function to avoid contrast induced nephropathy must be taken in to consideration.
Abbreviations:
CV: Cardiovascular, AVR: Aortic valve replacement, AS: Aortic Stenosis, MR: Mitral Regurgitation, AR: Aortic Regurgitation, PAP: Pulmonary Artery Pressure, RV: Right Ventricle, CTA: CT angiography, PA: Pulmonary Artery, TEE: Trans Esophageal Echocardiography, TTE: Trans Thoracic Echocardiography
AVA: Aortic Valve Area; CMR: Cardiovascular Magnetic Resonance Imaging; CT: Computed Tomography; ECG: Electrocardiogram; EF: Ejection Fraction; DSE: Dobutamine Stress Echocardiography; ESRD: End-Stage Renal Disease; GFR: Glomerular Filtration Rate; LFLG: Low-Flow Low-Gradient; LV: Left Ventricular; LVEF: Left Ventricular Ejection Fraction; MAC: Mitral Annular Calcification; MDCT: Multi Detector Computed Tomography; MRA: Magnetic Resonance Angiogram;
MRI: Magnetic Resonance Imaging; MS: Mitral Stenosis; PET: Positron Emission Tomography; TAVR: Trans-catheter Aortic Valve Replacement

## Specific CT measurements for TAVR

# Preprocedural Evaluation

## Aortic Valve Morphology
- Transthoracic Echocardiography (TTE) is performed for initial visualization of aortic valve to identify the number of leaflets; size, location, extent of calcification, leaflet motion, and a preliminary view of annular size and shape.
- If additional imaging is needed, valve anatomy and function can be evaluated by cardiac magnetic resonance imaging (CMR) or ECG-gated MDCT.

## Aortic Valve Function
Doppler echocardiography is superior to other imaging modalities to evaluate Aortic valve function. AS severity should be evaluated according to the ESE/ASE Recommendations for Evaluation of Valvular Stenosis and staged according to the AHA/ACC Guideline for the Management of Patients with Valvular Heart Disease.

## LV Geometry and Other Cardiac Findings
TTE also is recommended for evaluation of LV hypertrophy, chamber size, LV diastolic function, regional wall motion, and ejection fraction as well as newer measures of LV function such as global longitudinal strain. In addition, TTE is useful for assessment of aortic dilation, presence of subvalvular outflow tract obstruction, estimation of pulmonary pressures, and identification of other significant valve abnormalities.

## Annular Sizing
The 3D dataset provided by MDCT are more accurate than TTE findings regarding annular size. Measurement of LV outflow tract diameter on TTE has been well validated for
calculation of aortic valve area and continues to be the standard for determination of AS severity. CMR can also provide comprehensive assessment of the aortic valve, annulus,
and aortic root with good correlation with MDCT. CMR can be a valuable tool in patients who cannot undergo MDCT.

## Aortic Root Measurements
MDCT allows for the careful measurement of the size of the sinuses of Valsalva, the coronary ostia distance from the annulus, the size of the aorta at the sinotubular junction and 40mm above the annulus, and the extent and position of aortic calcifications.

## Presurgical Planning
MDCT also may be of use in identification of coronary artery and coronary bypass graft location and stenosis, evaluation of the RV to chest wall position, and identification of the aorta and LV apex to chest wall position in direct aortic approaches.

## Noncardiac Imaging
Because of high prevalence of dementia and atherosclerosis in this elderly patient population, a preprocedural work-up including carotid ultrasound and cerebrovascular MRI might be considered prior to considering or such patients for TAVR.

## Vascular Access
Because of the relatively large diameter of the delivery sheaths, appropriate vascular access imaging is critical for TAVR. It is important to evaluate the entire thoracoabdominal aorta, major thoracic arterial vasculature, carotids, and iliofemoral vasculature. MDCT is able to provide valuable dataset regarding vascular anatomy.

# Periprocedural Evaluation

## Interventional Planning
MDCT can assist with predicting the optimal delivery angle on fluoroscopy prior to valve deployment.

## Confirmation of annular sizing
Preprocedural MDCT is the best modality to evaluate annular size. At the time of the procedure, fluoroscopy is the main imaging modality. If questions remain about the correct annular
sizing, balloon inflation with contrast root injection can be performed. Also, 3D TEE is able to evaluate the annular size, at the time of the procedure.

## Valve Placement
Optimal deployment angles are obtained using fluoroscopy and root injections. Deployment is done under fluoroscopy at many institutions, although TEE is an alternative approach.

## Paravalvular Leak
TEE and TTE are required to assess the valve in different aspects. Also, TEE can be used to assess the immediate gradient changes after valve seating. Aortic root angiography also may be used to assess for regurgitation after valve implantation. As the volume of cases performed without general anesthesia increases, there may be an expanding role for periprocedural TTE.

## Procedural Complications
Immediate complications such as annular rupture resulting in pericardial effusion and tamponade can be detected by TEE, TTE, angiography, and direct hemodynamic measurements.

# Long-Term Postprocedural Evaluation

## Evaluate Valve Function
- Echocardiography is recommended to evaluate the valve postprocedurally to search for valvular and paravalvular leak, valve migration, complications such as annular or sinus rupture, valve thrombosis, endocarditis, paravalvular abscess, LV size, function and remodeling, and pulmonary pressures.
- MDCT can be used to evaluate valve anatomy A and to evaluate for valve thrombosis.
- CMR can also be used to quantify AR and can be complementary to TTE for the quantification of paravalvular leak.

## LV Geometry and Other Cardiac Findings
TTE is used to evaluate changes in LV function after TAVR.

# TAVR Procedure
The following table describes the TAVR procedure checklist.
Abbreviations:
AR: aortic regurgitation; AVR: aortic valve replacement; BAV: balloon aortic valvuloplasty; PA: pulmonary artery; TEE: transesophageal echocardiography

## Preprocedural Planning
- The Heart Valve Team must decide and plan for valve selection, access choice and location of procedure.

### Valve Choice
Valve selection is dependent on 2 major factors,
- Which type of valve should be considered (balloon expandable or self expanding) based on anatomical reasons
- Available valve sizes.
There currently are 2 TAVR valves commercially available in the United States:
- The balloon-expandable Sapien family of transcatheter heart valves (Edwards Lifesciences) made of bovine pericardium mounted in a cylindrical, relatively short cobaltchromium stent.
- The self-expanding CoreValve (Medtronic) family of transcatheter heart valves, which are made of porcine pericardium mounted in a taller, nitinol stent with an adaptive shape and supra-annular design.
Randomized clinical trials showed similar 1-year mortality, strokes, and re-admissions due to heart failure with either valve.
Important factors that must be considered in valve selection:
- Annulus dimensions and geometry
- Native valve and aortic root/LV outflow tract anatomy
- Coronary height
- Amount and distribution of calcification
Self expanding valves are preferred over balloon expandable in the following circumstances:
- Patients with heavy calcification of the aortic annulus/LV outflow tract with an attendant risk of rupture
- Extremely oval-shaped annulus or for transfemoral access when femoral artery diameter is between 5.0 and 5.5 mm.
Balloon expanding valves are preferred over self expandable in this situations:
- Dilated ascending (>43 mm) aorta
- Severely angulated aorta (aortoventricular angle >70 degrees, particularly for transfemoral access).
- A balloon-expandable valve is the only option in patients needing a transapical approach (e.g., those with a significant aortic calcification and peripheral vascular disease).
Several other valve designs and platforms are currently under investigation, and valve teams of the future will need to have a sound understanding of their relative merits and disadvantages for treating specific subsets of patients with AS.

### Access Choice
The patients atherosclerotic load and location, arterial size and tortuosity, and presence of mural thrombus are important factors in access selection.
When possible, transfemoral access is the preferred TAVR delivery route.

### Location of the Procedure
Optimal equipment requirements include a state of the art, large field of view fluoroscopic imaging system with a fixed overhead or floor mounted system that has positioning capability rather than a portable C-arm system. other equipment that are required in the TAVR center include: 3D echocardiography, MDCT, CMR, full catheterization laboratory hemodynamic capability, cardiopulmonary bypass machines and related ancillary supplies, with an inventory of interventional cardiology equipment for balloon aortic valvuloplasty, coronary balloons, stents, and 0.014-inch wires if coronary occlusion occurs as a complication of device deployment.
The procedure location should also be fully capable of providing anesthesia services, including advanced airway management, general anesthesia, full hemodynamic monitoring, and administration of vasoactive agents into the central circulation. 
In addition to the interventional cardiologist, cardiothoracic surgeon, and cardiovascular anesthesiologist, other personnel required during the TAVR procedure include a cardiovascular
imaging specialist, cardiac perfusionists, and other personnel trained in hemodynamic monitoring and able to rapidly deal with procedural complications.

### Anesthetic Considerations
Procedural complications, including hemodynamic collapse are common among patients undergoing TAVR. Preventing prolonged hypotension is a key goal during this procedure. Predictive factors for higher risk patients for intraprocedural instability include:
Depressed EF, elevated pulmonary pressures, significant mitral or tricuspid regurgitation, incomplete revascularization, collateral-dependent coronary and cerebral circulation, chronic lung disease, heart failure, and acute/chronic kidney disease.
TAVR is evolving from a procedure done routinely under general anesthesia with invasive central monitoring, a pulmonary artery catheter and transesophageal echocardiography to one that can safely be performed with conscious sedation and minimal instrumentation. Recent surveys showed better outcomes with conscious sedation than general anesthesia.
Now, it is recommended that TAVR procedures under conscious sedation should be performed in highly experienced centers, and not as an initial starting strategy for a TAVR program, and only using the transfemoral approach.
Conscious sedation is best avoided in patients requiring TEE guidance during valve deployment and in those with borderline vascular access, cognitive or language barriers, an inability to stay still or lie flat, chronic pain, morbid obesity, or other issues.

### Anticipated complication management
The following table summarizes the common complication for TAVR procedure and their treatment options.
Abbreviations:
AVR: aortic valve replacement; CABG: coronary artery bypass grafting; CPB: cardiopulmonary bypass; CVA: cerebrovascular accident; PCI: percutaneous coronary intervention; PPM: permanent pacemaker; SAVR: surgical aortic valve replacement; TAVR: transcatheter aortic valve replacement

## Procedural Details

### Anesthesia Administration
Typically, a temporary transvenous lead is passed through the femoral or internal jugular veins or, in the case of transapical procedures, can also be sewn directly on the epicardial surface. Arterial pressure monitoring may be done via the radial artery. At least 1 large-volume line is obtained peripherally or centrally. Immediate access to a defibrillator device
is necessary because ventricular fibrillation can occur with manipulation of catheters within the heart or with rapid ventricular pacing. Volume status needs to be supplemented carefully to prevent volume overload and hypovolemia. Inhaled nitric oxide or inhaled epoprostenol should be readily available for the treatment of severe pulmonary hypertension and right ventricular failure.
Routine surgical antibiotic prophylaxis administered prior to surgical incision or vascular access is warranted to decrease the risk of wound infection and endocarditis.

### Vascular Access
Vascular ultrasound may be needed to assess vessel wall calcification prior to puncture.
- For transfemoral access, both percutaneous and cutdown access approaches are used. Percutaneous approaches are preferred when access sites are relatively large and free of significant atherosclerotic disease and calcification, and in patients with wound healing concerns.
- For transapical cases, access is obtained via a left anterior thoracotomy, which is made after localization of the apex by fluoroscopy, TTE, and/or TEE.
- For transaortic cases, access is either through an upper partial sternotomy or a minthoracotomy at the second or third right intercostal space.

### Prevalve Implant
One of the key steps in preimplant is identifying the optimal fluoroscopic and intraprocedural views for device deployment. A pigtail catheter is typically placed in the noncoronary cusp (for self-expanding valves) and right coronary cusp (for balloon-expandable valves) and aortography is performed in a fluoroscopic view perpendicular to the native valve in order to identify the coplanar or coaxial view.
Anticoagulation therapy is usually initiated after insertion of the large sheath into the vasculature, and repeated to maintain an activated clotting time (ACT) of >250300 seconds.
Following this, the aortic valve is crossed using standard interventional techniques and a stiff wire exchange is performed, with redundancy in the LV cavity to prevent loss of position.
Prior to passage of the valve, predilation of the annulus may be required. Standard techniques of percutaneous balloon aortic valvuloplasty are employed, with rapid pacing during
inflation. Radiographic contrast opacification of the root during maximal inflation may provide useful information when the location of the coronary ostia in relation to the annulus and the
leaflet calcification or any other aortic root pathology requires further delineation. 
This is also helpful in situations where valve sizing falls between valve sizes. For example, use a 22-mm or 23-mm Edwards balloon when deciding between a 23-mm and a 26-mm transcatheter valve. If the 22-mm or 23-mm balloon reaches the hinge points and there is no significant leak around the balloon on angiography, then generally the 23-mm transcatheter valve would be selected. If the 22-mm balloon does not reach the hinge points and/or there is clear leak into the ventricle around the balloon, then the 26-mm valve would generally be implanted.

### Valve Delivery and Deployment
The transcatheter valve is positioned across the annulus in the predetermined coaxial annular plane. The optimal landing zone should be identified and will vary depending on the type of
valve.

### Post-deployment Valve Assessments
Immediately following implantation, valve position and location should be checked with echocardiography (TTE or TEE), hemodynamics, and/or aortography. A quick assessment for changes in MV or LV function and new pericardial effusion should also be routinely performed.
Post-TAVR AR must be characterized in terms of its location, severity, and cause and should integrate both central and paravalvular origins to allow for an estimate of overall volumetric impact.
Central regurgitation is generally a result of improper valve deployment or sizing. Paravalvular regurgitation is generally caused by underdeployment of the prosthesis, very low implants (e.g., below the valve skirt of the self-expanding valve), or calcific deposits, which prevent the valve unit from properly seating and sealing within the annulus. Acute leaks may respond to repeat ballooning of the valve to obtain a better seal and greater expansion of the valve.
Following TAVR deployment, the delivery system and sheath are removed. Anticoagulation is typically reversed and access site closure is performed.

# Post-TAVR Clinical Management
The long-term management of patients after TAVR is similar to that of patients after SAVR. The major differences are that patients undergoing TAVR tend to be older and have more comorbid
conditions; an access site replaces the surgical incision; and the long-term durability of transcatheter valves is not yet known.
Basic principles for management of patients after valve replacement include:
- Periodic monitoring of prosthetic valve function
- Management of comorbid conditions
- Monitoring for cardiac conduction defects and heart block
- Promotion of a healthy lifestyle with cardiac risk factor reduction
- Antithrombotic therapy as appropriate
- Optimal dental hygiene and endocarditis prophylaxis
- Patient education and coordination of care
- Cardiac rehabilitation and promotion of physical activity as appropriate.
The following table describes Checklist for Post-TAVR Clinical Management.
Abbreviations:
ACC:American College of Cardiology; ADLs: activities of daily living; AF: atrial fibrillation; AHA:
American Heart Association; AR: aortic regurgitation; ASA: aspirin; ECG: electrocardiogram; GI: gastrointestinal; LV: left ventricular; MD: medical doctor; NOAC: new oral anticoagulant; OT: occupational therapy; PA: pulmonary artery; PT: physical therapy; TAVR: transcatheter aortic valve replacement; VTE: venous thromboembolism.

## Immediate Postprocedure Management
After TAVR procedure, patients should be monitored for recovery from sedation and anesthesia.

### Waking from sedation
When general anesthesia is used, early extubation is encouraged, as for any general anesthesia procedure.

### Postprocedure Monitoring
Monitoring for mental status, telemetry, vital signs, volume status, postprocedure blood testing and access site for adequate hemostasis is required for either conscious sedation or general anesthesia.

### Pain Management
Appropriate pain management, continued mental status monitoring, and early mobilization are especially important post-TAVR as patients often are elderly with a high burden of comorbidities.

### Early Mobilization
Discharge plan should be prepared before the procedure and should include physical and occupational therapy.

### Discharge Planning
Early discharge (within 72 hours) does not increase the risk of 30-day mortality, bleeding, pacer implantation or re-hospitalization in selected patients undergoing transfemoral TAVR.

## Long Term Follow up

### Timing
Integration and coordination of medical care is essential post-TAVR to ensure optimal patient outcomes. Outcomes after TAVR depend strongly on overall patient health and clinical conditions other than the aortic valve disease.
Readmission rates are over 40% in the first year after the procedure, most often due to non-cardiac causes (60% of re-admissions); common readmission diagnoses include respiratory problems, infections and bleeding events. Cardiac re-admissions are most often for arrhythmias or heart failure.
Mortality rates after TAVR remain very high, with about 30% of patients dying within 3 years of the procedure. Non-cardiac causes of death predominate after the first 6 months. These data emphasize the need for integrated non-cardiac and cardiac care in these patients, including end-of-life planning.
The Heart Valve Team is responsible for care for the first 30 days because procedural complications are most likely in this time interval. After 30 days, there should be a formal transfer of care from the Heart Valve Team back to the referring primary cardiologist. In stable patients with no complications and few co-morbidities, the primary cardiologist should see the patient at 6 months and then annually, and more frequently as needed for complications or concurrent medical conditions. The primary care provider and cardiologist should communicate frequently to ensure coordination of care, with clear patient instructions on when and how to contact the care team.

### Antithrombotic Therapy
The current standard antithrombotic therapy after TAVR is clopidogrel 75 mg orally daily for 36 months with oral aspirin 75100 mg daily lifelong. Patients with chronic AF or
-ther indications for long-term anticoagulation should receive anticoagulation as per guidelines for AF in patients with prosthetic heart valves. Vitamin-K antagonist therapy may be
considered in the first 3 months after TAVR in patients at risk of AF or valve thrombosis, depending on the specific risk-benefit ratio in that patient. When vitamin-K antagonist therapy is
used, continuation of aspirin is reasonable, but it may be prudent to avoid other antiplatelet therapy in some patients given the increased risk of bleeding with multiple simultaneous antithrombotic agents.

### Concurrent Cardiac Disease
Long-term management focuses on treatment of comorbid cardiac and non-cardiac conditions.
non-cardiac conditions are best managed by the primary care provider or geriatrician, with the cardiologist providing consultation regarding any changes in cardiac signs or symptoms. Referral back to the Heart Valve Team is appropriate when prosthetic valve dysfunction is a concern or if a second interventional procedure might be needed for another valve or for coronary artery disease. In addition to echocardiography, periodic ECG monitoring is recommended for detection of asymptomatic AF and because heart block or other conduction defects can occur late after TAVR.

### Monitor for Post-TAVR Complications
Echocardiography before discharge provides a new baseline study of transcatheter valve function and should include:
the antegrade TAVR velocity, mean transaortic gradient, valve area, assessment of paravalvular AR, LV size, regional wall motion and ejection fraction, evaluation of MV anatomy and function, estimation of pulmonary pressures and evaluation of the right ventricle.
Repeat echocardiography is recommended at 30 days and then at least annually.
Routine ECG assessment is also recommended owing to a potential need for pacemaker implantation beyond the initial 30-day period, particularly following implantation of the self expanding
TAVR.
The TAVR procedure is associated with a high risk of dislodgement of microdebris from arch atheroma or from the valve itself with subsequent embolic stroke. Clinical cerebrovascular
event rates are around 3%5% at 30 days.

### Dental Hygiene and Antibiotic Prophylaxis
A TAVR is a risk factor for endocarditis, with reported rates of early prosthetic valve endocarditis ranging from 0.3% to 3.4 % per patient-year.
Standard antibiotic
prophylaxis after TAVR is the same as for all prosthetic valves per ACC Guidelines. In addition, patients should be encouraged to use optimal dental hygiene and see a dentist regularly for routine cleaning and dental care, with antibiotic prophylaxis at each visit.