Introduction
Heart valve team
-
The Heart Valve Team supervises and discusses all aspect of the TAVI selection process. A radiologist forms an integral part of this team.
Indications for TAVI
-
TAVI is primarily targeted at high-risk non-surgical patients with severe AS. Recent trials results indicate a potential expansion to intermediate-risk patients, as further evidence is gathered.
ACC/AHA* | ESC/EACTS^ | |
---|---|---|
Approach to care and clinical decision-making: | To be established by a shared decision of local heart team | To be made by a “heart team” with specific expertise in VHD |
Indications to the procedure: | Recommended in patients with indication to intervention for AS combined with a prohibitive surgical risk and a predicted post-procedural survival > 12 months | Indicated in patients with severe AS and contraindication to surgery, with an estimated life expectancy > 1 year and an expected improvement of QoL by TAVI |
General contraindications: | Overall procedural risks and contraindications based on scores evaluating patient’s frailty and disability plus cognitive and physical function | General absolute contraindications include the absence of a local “heart team” and/or an on-site cardiac surgery facility |
Importance of comorbidities: | Procedure considered futile if life expectancy < 1 year and/or survival with benefit < 25% at 2 years (i.e. lack of improvement in NYHA or CCS functional classes, quality of life or life expectancy) | Contraindicated In presence of extra-aortic valvular disease that can be treated only by surgery and/or in presence of an estimated life expectancy < 1 year and/or unlikely post-procedural improvement of QoL |
Anatomic contraindications: | Non-specified (considered part of the clinical decision-making process performed by local heart team) | Inadequate annulus sizing (i.e. < 18 mm and a 29 mm) Intracavitary thrombus, endocarditis, risk of coronary ostium obstruction and ascending aorta/arch unstable atheromasia Inadequate vascular access |
Diagnosis of severe aortic valve stenosis
-
The diagnosis and grading of severe aortic valve stenosis relies on the patients’ symptoms and imaging data regarding aortic valve anatomy & hemodynamics.
-
This imaging data is commonly acquired using Doppler echocardiography.
-
Quantification of the aortic valve calcification load based on CT for diagnostic purposes is only necessary in selected patients with a discordant result on Doppler echocardiography.
-
MRI can be used for quantification of the aortic valve opening area and transvalvular velocities using planimetry and phase contrast imaging with simultaneous LV ejection fraction calculation
Pre-procedural comorbidities and incidental findings
-
CT must not be routinely used for pre-procedural evaluation of coronary artery disease. However, as technology evolves, it can be used for this indication on a case-by-case basis and according to local expertise and available equipment and mainly to exclude significant coronary stenosis.
-
Repercussions of incidental findings, including the presence of malignancy, must be evaluated by the Heart Valve Team on a case-by-case basis with regards to their influence on procedural success and prognosis. Every finding that can influence the procedure and its outcome must be reported.
Types of valvular devices and access sites
-
Balloon-expandable and self-expandable valves have different physical properties and possible access strategies. Therefore, sizing algorithms are not simply interchangeable and do not follow specific guidelines.
-
The choice for a valve type mainly depends on the experience of the Heart Valve Team with a particular valve, and on the available access routes.
SAPIEN 3 | Evolut PRO/R | |
---|---|---|
Manufacturer | Edwards Lifesciences | Medtronic |
Available sizes (mm) | 20 | 23 |
23 | 26 | |
26 | 29 | |
29 | 34 | |
Annular range TEE (mm) | 16–28 | 17/18–30 (17 for valve-in-valve only) |
Deployment | Balloon-expandable | Self-expandable |
Frame | Cobalt-chromium | Nitinol |
Frame height (mm) | 18–22.5 | 45 (46 mm for 34-mm valve) |
Pericardial leaflets | Bovine | Porcine |
Valve function | Intra-annular | Supra-annular |
Repositionable | No | Yes |
Ascending aorta fixation | No | No |
Access routes | Transfemoral | Transfemoral |
Transapical | Transaxillary | |
Transaortic | Transaortic | |
Transfemoral delivery sheath size | 14F (16F for 29 mm valve) | 16F |
Standardisation of scanning protocols
-
The CT acquisition protocol should at least include a contrast enhanced ECG-gated or triggered scan of the aortic root reconstructed with 1.0 mm or less slice thickness, preferably with several reconstructed phases but at least including a systolic phase.
-
A contrast enhanced CT scan with a scan range that at least extends from the subclavian arteries to the superficial femoral arteries at the level of the femoral head is required.
-
Both scans may be obtained from a single acquisition but in most cases two separate acquisitions (one for the aortic root and one for the vascular access) during the same session are preferable.
-
Tailoring CT acquisition protocols to lower the required volume of contrast material prevails over radiation dose reduction given the fragile nature of the patient population and the need for high quality images, with the newer CT systems having the possibility to use one contrast bolus for evaluation of access route and valve area.
-
MR can be used as an alternative to CT for TAVI planning but is more complex and may be considered in patients with severely depressed renal function given the availability of unenhanced MRI protocols.
CT
General scanner and acquisition requirements
CTA of the aortic root
CTA of the aorta and iliac arteries
Contrast administration/volume
Medication
MRI protocol
Required CT-derived measurements and imaging features before the procedure: recommended stepwise approach
-
The main elements of CT in annular sizing are:
-
to define a cross-sectional double-oblique image orientation in the correct plane of the aortic annulus
-
to obtain accurate and standardised measurements of different annular dimensions and height of coronary ostia
-
to implement these measurements in the selection process of a TAVI candidate in order to have the optimal prosthesis-patient matching
-
ECG-gated acquisitions are mandatory, with a preference for systolic measurements.
-
Evaluation of all potential access routes for suitability is mandatory.
-
For valve-in-valve procedures, simulated TAVI insertion is mandatory to assess potential coronary obstruction.
Anatomy | Component | Characteristics |
---|---|---|
Aortic valve | ||
Cuspidity | Bicuspid/tricuspid/undefinable | |
Valvular calcifications | Amount (absent to severe)/location/distribution | |
Subvalvular calcifications | Present or not, location, amount | |
Quantification of valve leaflet calcification | Use the Agatston method, only indicated in discrepant Doppler echocardiography results | |
Aortic annulus | ||
short- and long-axis diameter (mm) | Systolic measurements preferred, ensure correct double-oblique annular plane orientation | |
Perimeter (mm) | ||
Area (mm2) | ||
Aortic sinus | ||
Height (mm) | Requirements differ from type of THV and manufacturer | |
Width (mm) | ||
Distance from annular plane to coronary ostia (mm) | ||
Diameter sinotubular junction (mm) | ||
Aorta | ||
Maximum cross-sectional diameter of ascending aorta (mm) | ||
Cross-sectional diameter at different levels (mm) | ||
Wall characteristics | Amount and distribution of calcification, thrombus, ulcerative plaques, other findings | |
Access route | ||
Diameter subclavian and common carotid arteries (mm) | Minimal luminal diameters are required | |
diameter of brachiocephalic trunk (mm) | ||
Diameter of common and external iliac arteries (mm) | ||
Diameter of common femoral arteries | ||
Wall characteristics | Amount and distribution of calcification, thrombus, ulcerative plaques, other findings | |
Left ventricular apex | Myocardium characteristics, presence of thrombus, other findings | |
Ascending aorta | Wall characteristics, especially anterior and antero-lateral wall for transaortic access |
Essential aortic root assessment
Aortic valve cuspidity
Amount, location and distribution of valvular calcifications
Semi-quantitative pre-TAVI grading of valvular calcifications | |
---|---|
Absent | No calcifications |
Mild | Small isolated focal spots not involving commissures and attachments sites |
Moderate | Large confluent calcifications affecting 2 cusps or Small isolated focal spots at the level of all commissures and attachments sites |
Severe | Large confluent calcifications affecting all cusps |
Planimetry of the annular plane (see Supplementary Material 2–4)
- Obtaining a cross-sectional image orientation in the correct plane of the aortic annulus
- Correctly and standardised measuring the annulus using different methods
- Implementing these measurements in the selection process of a patient-specific THV size.
Additional recommended measurements in the aortic root
Minimum distance of the annulus to the left and right ostium of the coronary arteries (see Supplementary Material 5–6)
Largest dimensions of the aortic sinus and sinotubular junction (see Supplementary Material 7–8)
Determination of optimal c-arm angulation
Measurements for valve-in-valve procedures
Evaluation of the access route
- Amount and distribution of atherosclerotic (specifically circumferential) wall thrombi and calcifications
- Small native vessel size (below the outer diameter of the used delivery sheath)
- Prominent tortuosity of the iliac arteries and aorta.
Endovascular approach
Non-endovascular approach
Recommended standardised medical report in pre-TAVI assessment
-
The report of a pre-TAVI assessment CT or MRI should include all relevant information and measurements of the aortic root and access routes.
-
Structured reports are highly recommended to ensure all relevant information is included and facilitate communication of results.