TAVR imaging

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1],Associate Editor(s)-in-Chief: Seyedmahdi Pahlavani, M.D. [2]

Overview

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.

Definition

AS severity is defined based on imaging findings. Severe symptomatic (Stage D) AS is considered as TAVR candidate.

Abbreviations: ΔP: mean gradient, Vmax: maximum aortic velocity, AVA: aortic valve area. AS: aortic stenosis, AR: aortic regurgitation.

Severe symptomatic AS (stage D)
STAGE	DEFINITION	SYMPTOMS	VALVE ANATOMY	VALVE HEMODYNAMICS	HEMODYNAMIC CONSEQUENCES
D1	Symptomatic severe high-gradient AS	Exertional dyspnea or decreased exercise tolerance Exertional angina Exertional syncope or presyncope	Severe calcification or congenital stenosis with severely reduced opening	Vmax ≥ 4 m/s or mean ΔP ≥ 40 mmHg AVA ≤ 1.0 cm² but may be larger with mixed AS and AR	LV diastolic dysfunction Left ventricular hypertrophy May present with pulmonary hypertension
D2	Symptomatic severe low-flow/low gradient AS with reduced LVEF	Heart failure Angina Syncope or presyncope	Severe calcification or congenital stenosis with severely reduced leaflet motion	AVA ≤ 1.0 cm² with resting aortic Vmax < 4 m/s or mean ΔP ≥ 40 mmHg Dobutamine stress echo shows AVA ≤ 1.0 cm² with Vmax ≥ 4 m/s at any flow rate	LV diastolic dysfunction Left ventricular hypertrophy LVEF <50%
D3	Symptomatic severe low gradient with normal LVEF	Heart failure Angina Syncope or presyncope	Severe calcification with severely reduced leaflet motion	AVA ≤ 1.0 cm² with Vmax < 4 m/s or mean ΔP ≤ 40 mmHg AVA ≤ 0.6 cm² Stroke volume index < 35 mL/m²	Increased LV relative wall thickness Small LV chamber with low stroke volume Restrictive diastolic filling LVEF ≥ 50%

TAVR imaging checklist

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

TAVR Imaging Checklist
Region of Interest	Recommended Approach and Key Measures	Additional Comments
Preprocedure
Aortic valve morphology	TTE: Trileaflet, bicuspid or unicuspid Valve calcification Leaflet motion Annular size and shape	TEE if can be safely performed, particularly useful for subaortic membranes Cardiac MRI if echocardiography nondiagnostic ECG-gated thoracic CTA if MRI contraindicated
Aortic valve function	TTE: Maximum aortic velocity Mean aortic valve gradient Aortic valve area Stroke volume index Presence and severity of AR	Additional parameters Dimensionless index AVA by planimetry (echo, CT, MRI) Dobutamine stress echocardiography for LFLG AS-Reduced EF Aortic valve calcium score if LFLG AS diagnosis in question
LV Geometry and other cardiac findings	TTE: LVEF, regional wall motion Hypertrophy, diastolic dysfunction Pulmonary pressure estimate Mitral valve (MR, MS, MAC) Aortic sinus anatomy and size	Myocardial ischemia and scar: CMR, PET, DSE, thallium CMR imaging for myocardial fibrosis and scar, identification of cardiomyopathies
Annular sizing	TAVR CTA- gated contrast enhanced CT thorax with multiphasic acquisition Typically reconstructed in systole 30-40% of the R-R window	Major/minor annulus dimension Major/minor average Annular area Circumference/perimeter
Aortic root measurements	Gated contrast-enhanced CT thorax with multiphasic acquisition. Typically reconstructed in diastole 60%–80%.	Coronary ostia heights Midsinus of Valsalva (sinus to commissure, sinus to sinus) Sinotubular junction Ascending aorta (40 cm above valve plane, widest dimension, at level of PA) Aortic root and ascending aorta calcification
Coronary disease and thoracic anatomy	Coronary angiography Nongated thoracic CTA	Coronary artery disease severity Bypass grafts: number/location RV to chest wall distance Aorta to chest wall relationship
Noncardiac imaging	Carotid ultrasound Cerebrovascular MRI	May be considered depending on clinical history

Vascular Access
Kidney Function Status	Recommended Approach	Key Parameters
Normal renal function (GFR >60) or ESRD not expected to recover	TAVR CTA	Aorta, great vessel, and abdominal aorta Dissection; atheroma; stenosis; calcification Iliac/subclavian/femoral luminal dimensions, calcification, and tortuosity
Borderline renal function	Contrast MRA Direct femoral angiography (low contrast)	Institutional dependent protocols Luminal dimensions and tortuosity of peripheral vasculature
Acute kidney injury or ESRD with expected recovery	Noncontrast CT of chest, abdomen, and pelvis Noncontrast MRA Can consider TEE if balancing risk/benefits	Degree of calcification and tortuosity of peripheral vasculature

TAVR Imaging Checklist
Imaging goals	Recommended Approach	Additional Details
Periprocedure
Interventional planning	TAVR CTA	Predict optimal fluoroscopy angles for valve deployment
Confirmation of annular sizing	Preprocedure MDCT	Consider contrast aortic root injection if needed 3C TEE to confirm annular size
Valve placement	Fluoroscopy under general anesthesia	TEE (if using general anesthesia)
Paravalvular leak	Direct aortic root angiography	TEE (if using general anesthesia)
Procedural complications	TTE TEE (if using general anesthesia) Intracardiac echocardiography (alternative)
Long-term Postprocedure
Evaluate valve function	TTE	Key elements of echocardiography: Maximum aortic velocity Mean aortic valve gradient Aortic valve area Paravalvular and valvular AR
LV geometry and other cardiac findings	TTE: LVEF, regional wall motion Hypertrophy, diastolic fucntion Pulmonary pressure estimate Mitral valve (MR, MS, MAC)

Specific CT measurements for TAVR

TAVR CT Measurement Summary
Valve Size and Type
Region of Interest	Specific Measurements	Measurement Technique	Additional Comments
Aortic valve morphology and function	Aortic valve	If cine images obtained, qualitative evaluation of valve opening Planimetry of aortic valve area in rare cases Calcium score with Agatston technique or a volumetric technique to quantify calcification of aortic valve	Most useful in cases of LFLG AS where diagnosis is otherwise unclear. May be helpful in defining number of valve cusps.
LV geometry and other cardiac findings	LV outflow tract	Measured with a double oblique plane at narrowest portion of the LV outflow tract Perimeter Area Qualitative assessment of calcification	Quantification of calcification not standardized. Large eccentric calcium may predispose for paravalvular regurgitation and annular rupture during valve deployment.
Annular sizing	Aortic annulus	Defined as double oblique plane at insertion point of all 3 coronary cusps Major/minor diameter Perimeter Area	Periprocedural TEE and/or balloon sizing can confirm dimensions during case.
Aortic root measurements	Sinus of Valsalva	Height from annulus to superior aspect of each coronary cusp Diameter of each coronary cusp to the opposite commissure Circumference around largest dimension Area of the largest dimension
Coronary and thoracic anatomy	Coronary arteries	Height from annulus to inferior margin of left main coronary artery and the inferior margin of the right coronary artery	Short coronary artery height increases risk of procedure. Evaluation of coronary artery and bypass graft stenosis on select studies. Estimate risk of coronary occlusion during valve deployment.
	Aortic root angulation	Angle of root to left ventricle Three-cusp angulation to predict best fluoroscopy angle	Reduce procedure time and contrast load by reducing number of periprocedural root injections
Vascular Access Planning
Vascular access	Aorta	Major/minor diameters of the following: Aorta at sinotubular junction Ascending aorta in widest dimension Ascending aorta prior to brachiocephalic artery Midaortic arch Descending aorta at isthmus Descending aorta at level of pulmonary artery Descending aorta at level of diaphragm Abdominal aorta at level of renal arteries Abdominal aorta at the iliac bifurcation	Measurements must be perpendicular to aorta in 2 orthogonal planes. Identify aortopathies. Evaluate burden of atherosclerosis. Identify dissection or aneurysms.
	Primary peripheral vasculature	Major/minor dimensions, tortuosity, calcification of the following: Carotid arteries Subclavian arteries Bracheocephalic artery Vertebral arteries Bilateral subclavian arteries Great vessels Iliac arteries Femoral arteries	No well-defined cutoff or definition of tortuosity or calcification has been established.
	Ancillary vasculature	Stenosis of the following: Celiac artery Superior mesenteric artery Both renal arteries
	Relationship of femoral bifurcation and femoral head	Distance from inferior margin of femoral head to femoral biforcation

TAVR Imaging Evaluation

TAVR CT

ECHO

Non-gated Angiogram of Chest, Abdomen and Pelvic arteries for vascular access selection

ECG gated CT of annulus and Aortic root for valve sizing selection

Left ventricles and other findings

Confirm severe Aortic Stenosis

Transfemoral Approach

Annular sizing

Aortic Root sizing

Additional Procedural Planning

Subclavian Approach

Major/Minor Dimension

Coronary Ostia height

Fluoroscopy Angulation

LVEF and LV dimension

High gradient AS

Apical Approach

Area

Aortic Sinus to Commissure dimension

Bypass Grafts

Estimated Pulmonary pressure

Low gradient AS

Other Approaches

Circumferences

Sinotubular Junction

RV to Chest wall position

Other valvular abnormalities

Reduced EF

Carotid

Ascending Aorta dimension

Preserved EF

Direct Aortic

Aortic Calcification

Transvenous

References