Aortic regurgitation
Aetiology
Aortic regurgitation (AR) can be caused by:
- primary disease of the aortic valve
- diseases of the aorta in the area of aortic root
Aortic root disease causes secondary AR due to the dilation of the aortic root. The percentage of patients with AR due to aortic root disease has been rising and is now more common than primary valve disease in patients undergoing surgical aortic valve replacement.
Image 1 Causes of aortic regurgitation
Symptoms
Patients with AR can remain asymptomatic for a considerable period of time and symptoms usually develop gradually as the severity of the AR progresses.
As a result of AR, the left ventricle enlarges and patients may develop symptoms of myocardial dysfunction and cardiomegaly.
Commonly reported symptoms include:
- exertional dyspnea
- orthopnea
- paroxysmal nocturnal dyspnea
- angina pectoris
- nocturnal angina sometimes accompanied by diaphoresis
- cardiomegaly may result in the uncomfortable awareness of heartbeat.
Physical examination
Several features can be observed in patients with AR, particularly when the AR is severe.
These include:
- Corrigan pulse (abrupt distention and quick collapse)
- Musset sign (head movement synchronized with heartbeat)
- Quincke sign can be appreciated during hand examination and signifies capillary pulsations visible under/through the fingernails
Several other less frequently observed signs of AR exist, including:
- Mûller sign (movement of the uvula)
- Landolfi’s sign (pupil dilation and constriction)
Auscultation
Soft, high-pitched, early diastolic decrescendo murmur heard best at the 3rd intercostal space on the left (Erb's point). Additionally, an early diastolic rumble may also be heard at the apex due to the regurgitant jet striking the anterior leaflet of the mitral valve causing it to vibrate (Austin-Flint murmur).
Echocardiography diagnosis
Echo allows for assessment of the valve morphology (number of cusps), identify the underlying mechanism of AR and evaluate the severity of AR. Additionally, it allows for measurement of left ventricle dimensions and function and is used to measure the dimensions of the aortic root and ascending aorta.
1) Valve morphology
Transthoracic echocardiography (TTE) can be used to evaluate the morphology of the aortic valve. However, transesophageal echocardiography (TEE) may be needed if the morphology cannot be sufficiently evaluated by TTE.
Based on ECHO appearance, AR can be categorised by type and grade of calcifications.
Image 2 Different mechanisms leading to aortic regurgitation
Adapted from: Lancellotti P, Tribouilloy C, Hagendorff A, et al. Scientific Document Committee of the European Association of Cardiovascular Imaging. Recommendations for the echocardiographic assessment of native valvular regurgitation: an executive summary from the European Association of Cardiovascular Imaging. Eur Heart J Cardiovasc Imaging. 2013 Jul;14(7):611-44.
Video 1 Tricuspid aortic valve with degenerative changes leading to aortic regurgitation - PSAX
Video 2 Bicuspid aortic valve leading to aortic regurgitation - PSAX view
Video 3 Aortic regurgitation caused by bicuspid aortic valve - TEE, 3D
Video 4 Aortic root dilatation leading to aortic regurgitation - PLAX view
Image 3 Aortic root dilatation (measurement of valsalva sinus) leading to aortic regurgitation - PLAX view
Video 5 Infective endocarditis of aortic valve leading to massive aortic regurgitation - PLAX view
Two dimensional mode or M mode can used to obtain dimensions, Information about the cusp pathology (redundancy, restriction, cusp height to indicate likely adequacy of coaptation, mobility/pliability, thickness, integrity), commissure variations (fusion, splaying, attachment site, and alignment) and root morphology.
1) The parasternal long-axis view is classically used to measure the LV outflow tract, the aortic annulus, and the aortic sinuses dimensions.
2) The parasternal long-axis view, the parasternal short-axis view and the apical five-chamber view allow for assessment of leaflet thickness and morphology.
2) Severity of Aortic regurgitation
The severity of AR is assessed using:
- A) Colour flow Doppler
- B) Continuous wave Doppler
- C) Pulsed Doppler
Image 4 Grading of AR severity
Lancellotti P et al. Recommendations for the echocardiographic assessment of native valvular regurgitation: an executive summary from the European Association of Cardiovascular Imaging. Eur Heart J Cardiovasc Imaging 2013;14:611-644.
A) Colour flow Doppler imaging
To visualize the AR with colour flow imaging, the parasternal long-axis, A4C or A3C view are used.
Colour flow imaging is helpful in establishing the diagnosis of AR and general overview but the length or area of the jet is not sufficient to assess the severity of the condition.
It provides information about the position of the jet (central or eccentric).
To assess the severity of the AR, the size of the vena contracta (VC) is needed.
Vena contracta
Vena contracta (VC) = represents the smallest flow diameter at the level of the aortic valve in the LV outflow tract, immediately below the flow convergence region.
From the size of the VC, the effective regurgitant orifice area (EROA) can be estimated.
There are however several limitations to the concept of VC measurement and EROA estimation. First is the presence of multiple jets and the second is the assumption that the regurgitant orifice is circular, which is often not. For this reason, a confirmation of the severity of AR by other method is needed, especially if the VC width is between 3-6mm.
Vena contracta ≥6mm favours severe AoR.
The flow convergence method can also be used to estimate the AR severity. It is based on imaging of the flow convergence zone obtained from the apical three or five-chamber or parasternal long-axis or upper right parasternal views. However, this method also has several limitations. It is not feasible in a high percentage of patients and may provide inaccurate results in patients with obtuse flow convergence angles (aneurysmal dilation of the ascending aorta) or those with confined flow convergence zone (cusp perforation or commissural leaks).
Video 6 Aortic regurgitation (grade 1-2/4) - PLAX view, Color flow Doppler
Video 7 Aortic regurgitation (grade 2/4)- zoomed PLAX, Color flow Doppler
Video 8 Aortic regurgitation (grade 2/4)- PSAX view, color flow Doppler
Video 9 Aortic regurgitation (grade 2-3/4) - A5C view, Color flow Doppler
Video 10 Aortic regurgitation (grade 2-3/4) - A3C view, Color flow Doppler
Image 4 Vena contracta measurement in severe aortic regurgitation (8 mm)- PLAX view
Video 11 Severe aortic regurgitation (grade 4/4), PLAX view
Video 12 Focused view on severe aortic regurgitation, PLAX view
Video 13 Massive aortic regurgitation due to infective endocarditis - A3C
B) Continuous wave (CW) Doppler
CW Doppler should be obtained from the apical five-chamber view or the right parasternal window in case of eccentric jets.
From the rate of deceleration the pressure half-time (PHT) can be derived. The shorter the PHT, the more severe the AR.
Severe AR typically presents with PHT of <200 ms and a value of PHT of >500 ms is usually found in mild AR.
The pressure half-time is influenced by: a) chamber compliance, b) the acuteness of AR (i.e. in severe acute AR, the PHT is almost always short), c) the aorto-ventricular pressure gradient.
Image 5 PHT measurement in chronic compensated aortic regurgitation (586ms)- A5C
C) Pulsed wave Doppler
The pulse wave (PW) Doppler method can also be used to quantify the AR severity in the form of the volumetric method or diastolic flow reversal method.
Diastolic flow reversal in the descending aorta should be considered as the strongest additional parameter for evaluating the severity of AR.
How is it measured?
The flow reversal is best imaged in the upper descending aorta at the aortic isthmus level from a suprasternal view by using PW Doppler.
The sample volume is placed just distal to the origin of the left subclavican artery and it is aligned as much as possible along the major axis of the aorta.
With milder degrees of regurgitation, there is a brief reversal of flow limited to early diastole. As the degree of the regurgitation increases, the duration and the velocity of the reversal flow during diastole increase.
It becomes sustained throughout diastole at velocities exceeding 20 cm/s in severe AR (end-diastolic velocity measured at peak R-wave).
Image 6 Holodiastolic flow reversal in descending aorta (0.20 m/s)
Image 7 Holodiastolic flow reversal in descending aorta=corresponding to severe AR (0.30 m/s)
Other ECHO parameters that should always be measured and reported:
- LV diameters = ESD and EDD are very important factors in decision making for surgery !
- volumes
- ejection fraction = another important factor in decision making for surgery !
Image 8 Standard EDD and ESD measurements in aortic regurgitation - PLAX, M-mode
CT/Cardiac MR
CMR should be used to quantify the regurgitant fraction when echocardiographic measurements are equivocal.
CT scan should be obtained in patients with aortic dilation. CT is also used for measurements needed for indication for surgery.
Diameters are measured using the inner-inner edge technique at end diastole on the strictly transverse plane. Diameters at the annulus, sinus of Valsalva, sinotubular junction, tubular ascending aorta and aortic arch level should be reported.
Management
Indications for surgery
A step by step approach to patients with chronic AR is part of the latest guidelines and is presented below. In summary, patients with severe AR should undergo operation if they are:
- symptomatic
or
they have:
- impairment of LV function (ejection fraction ≤50%)
- LV enlargement with an LV end-diastolic diameter (LVEDD) >70 mm
- left ventricular end-systolic diameter (LVESD) >50 mm
Surgery is also indicated in all patients with Marfan syndrome and a maximal aortic diameter ≥50 mm.
In patients with Marfan syndrome and additional risk factors and in patients with a TGFBR1 or TGFBR2 mutation (including Loeys–Dietz syndrome), surgery should be considered at a maximal aortic diameter ≥45 mm.
Additionally, for patients who have an indication for aortic valve surgery, an aortic diameter ≥45 mm is considered to indicate concomitant surgery of the aortic root or tubular ascending aorta.
1) Surgery
Valve replacement is the standard procedure in the majority of patients with aortic regurgitation, but valve repair surgery should be considered in patients with pliable non-calcified tricuspid or bicuspid valves who have a type I or type II mechanism of aortic regurgitation.
All the indications assume the operative risk is not prohibitive. If the operative risk is prohibitive or if patients remain symptomatic after surgery, medical therapy can provide symptomatic relief.
2) Medical therapy
Medications used in patients with heart failure due to AR are angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs) and beta-blockers. In patients with Marfan syndrome, beta-blockers and/or losartan may slow aortic root dilatation and reduce the risk of aortic complications and should be considered before and after surgery.
Follow-up
All asymptomatic patients with severe aortic regurgitation and normal LV function should be seen for follow-up at least every year.
In patients with a first diagnosis, or if LV diameter and/or ejection fraction show significant changes or come close to thresholds for surgery, follow-up should be continued at 3–6-month intervals.
If the ascending aorta is dilated (>40 mm) it is recommended to perform CT or CMR.
Image 9 Indications for surgery in patients with severe aortic stenosis
Vahanian A, Beyersdorf F, Praz F, et al. ESC/EACTS Scientific Document Group. 2021 ESC/EACTS Guidelines for the management of valvular heart disease. Eur Heart J. 2021 Aug 28:ehab395. doi: 10.1093/eurheartj/ehab395. Epub ahead of print. PMID: 34453165.
Image 10 Indications for surgery in patients with severe aortic regurgitation
Vahanian A, Beyersdorf F, Praz F, et al. ESC/EACTS Scientific Document Group. 2021 ESC/EACTS Guidelines for the management of valvular heart disease. Eur Heart J. 2021 Aug 28:ehab395. doi: 10.1093/eurheartj/ehab395. Epub ahead of print. PMID: 34453165.
References
- Alec Vahanian, Friedhelm Beyersdorf, Fabien Praz, Milan Milojevic, Stephan Baldus, Johann Bauersachs, Davide Capodanno, Lenard Conradi, Michele De Bonis, Ruggero De Paulis, Victoria Delgado, Nick Freemantle, Martine Gilard, Kristina H Haugaa, Anders Jeppsson, Peter Jüni, Luc Pierard, Bernard D Prendergast, J Rafael Sádaba, Christophe Tribouilloy, Wojtek Wojakowski, ESC/EACTS Scientific Document Group, 2021 ESC/EACTS Guidelines for the management of valvular heart disease: Developed by the Task Force for the management of valvular heart disease of the European Society of Cardiology (ESC) and the European Association for Cardio-Thoracic Surgery (EACTS), European Heart Journal, 2021;, ehab395, https://doi.org/10.1093/eurheartj/ehab395
- Patrizio Lancellotti, Christophe Tribouilloy, Andreas Hagendorff, Bogdan A. Popescu, Thor Edvardsen, Luc A. Pierard, Luigi Badano, Jose L. Zamorano, On behalf of the Scientific Document Committee of the European Association of Cardiovascular Imaging: Thor Edvardsen, Oliver Bruder, Bernard Cosyns, Erwan Donal, Raluca Dulgheru, Maurizio Galderisi, Patrizio Lancellotti, Denisa Muraru, Koen Nieman, Rosa Sicari, Document reviewers: Erwan Donal, Kristina Haugaa, Giovanni La Canna, Julien Magne, Edyta Plonska, Recommendations for the echocardiographic assessment of native valvular regurgitation: an executive summary from the European Association of Cardiovascular Imaging, European Heart Journal - Cardiovascular Imaging, Volume 14, Issue 7, July 2013, Pages 611–644, https://doi.org/10.1093/ehjci/jet105
- Zipes, Peter Libby, Robert O. Bonow ; founding editor and online editor Eugene Braunwald. Braunwald's Heart Disease : a Textbook of Cardiovascular Medicine. Philadelphia, PA :Elsevier/Saunders, 2015
