Aortic regurgitation

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Aortic regurgitation: Reverse blood flow from aortic valve to left ventricle cavity due to valve disease, aortic root damage or both.


Contents

Pathophysiology

The inability of the aortic valve leaflets to remain closed during diastole results in a portion of the left ventricular stroke volume leaking back from the aorta into ventricle cavity. The added volume of regurgitant blood produces an increase in left ventricular end-diastolic volume and an elevation in wall tension[1]

Aetiology and morphological features on 2-D echocardiography

Table 1: Aetiology of aortic regurgitation

Diseases of the aortic valve leaflet Diseases of the aorta
Bicuspid aortic valve Aortic dissection
Rheumatic heart disease Aortic aneurysm
Infective Endocarditis Marfan's syndrome
Myxomatous valve disease Inflammatory diseases
Drugs Trauma
Prosthetic valve dysfunction


Video 1 Video 2

Diseases of the aortic valve leaflet

  • Bicuspid aortic valve (videos 1 and 2, showing a 2D an colour doppler paraesternal short axis view of a bicuspid aortic valve): Most common variety is a fusion between right and left coronary cusps.Thickening at the site of fusion may be present in the form of a raphe. An eccentric closure line in M-mode is suggestive.
  • Rheumatic heart disease: A rheumatic valve commonly shows thickening of the borders of the leaflets and fusion of the commissures.
  • Infective Endocarditis causes aortic regurgitation due to the presence of vegetation preventing diastolic coaptation or due to perforation of the leaflet
  • Myxomatous valve disease can affect Aortic as well as mitral valve leaflets
  • age related degeneration (Calcific degenerative aortic regurgitation): Echodense calcified leaflets with reduced movement.
  • Medications like fenfluramine have been reported to cause aortic regurgitation
  • Prosthetic valve dysfunction

Diseases of the aorta

  • Aortic dissection can cause regurgitation either by dilatation of the annulus or by disruption of the leaflets
  • Aortic aneurysm
  • Marfan's syndrome results in dilatation of the aortic root.
  • Inflammatory diseases: Syphilitic aortitis, Ankylosing spondylitis, Rheumatoid arthritis, SLE
  • Trauma[2]

Indications of echocardiography in aortic regurgitation

  1. Confirm diagnosis of aortic regurgitation.
  2. Assess the regurgitation mechanism: evaluate leaflet´s anatomy, aortic root and ascending aorta.
  3. Assess aortic regurgitation severity.
  4. Evaluate left ventricle dimensions, ventricular mass, systolic and diastolic function and pulmonary hypertension[3]

Echocardiographic assessment of severity

Left ventricle evaluation: Quantitative assessment of LV diameters, volumes, and ejection fraction is mandatory in patients with aortic regurgitation as additional hemodynamic assessment[4].



Doppler echocardiography


Colour flow Doppler

(Figures 1 and 2, videos 3,4,5,6)

Video 3 Video 4
Video 5 Video 6


Colour flow mapping can be used to identify and describe the regurgitant flow. The analysis of the three components of the regurgitant jet with colour doppler (flow convergence zone, vena contracta, and jet turbulence) has improved the estimation of the aortic regurgitation severity. Colour flow doppler helps to assess whether the regurgitation is valvular or paravalvular. It can also help to determine whether the regurgitant jet is central, eccentric or through a perforation.

Colour flow imaging: The colour imaging of the regurgitant jet is useful for a visual assessment of the regurgitation[4]

Table 2. Aortic regurgitation (AR) severity: qualitative methods.[4]

Qualitative parameters Mild Moderate Severe
Aortic Valve Morphology Normal/Abnormal Normal/Abnormal Abnormal, flail, large coaptation deffect
Color flow Aortic Regurgitation jet widh Small in central jet Intermediate Large
Continuos wave signal of AR jet Incomplete Dense Dense
Diastolic flow reversal in descending aorta Protodiastolic Intermediate Holodiastolic


It is a technical factors dependent method. Jet width should be measured just below the leaflets in paraesternal long axis. It can also be evaluated the relationship between the regurgitant jet width and the left ventricle outflow tract diameter and both areas (regurgitant jet and left ventricle outflow tract). Values (jet width): Mild: <0,3cm Moderate: 0,3-0,6cm Severe: > 0,6 cm Values (jet width/Left ventricle outflow tract width): Mild: <25% Moderate: 26-64% Severe: >64% Values (jet area/left ventricle outflow tract area): Mild: <5% Moderate: 5-59% Severe: >59%[3]


The vena contracta is the narrowest region of the regurgitant jet downstream from the regurgitant orifice. It is smaller than regurgitant orifice and a high velocity laminar flow is typical. In contrast to the regurgitant jet, the vena contracta is considerably less sensitive to technical factors and relatively independent of flow rate. Values: Mild: <0,3 cm; Moderate: 0,3-0,59cm; Severe >0,6cm[5][6][7].


The proximal isovelocity surface area: PISA is also known as flow convergence method. It is a quantitative approach that is based on the principle of conservation of mass. It is used to calculate the effective regurgitant orifice area (EROA). The surface area of the PISA region is 2πr2, where r is the radius from the aliasing line to the orifice[8].


Effective regurgitant orifice area can be calculated using the instantaneous regurgitant flow. The formula can be derived from the following:

Valiasing * 2πr2 = Vmax * EROA

hence:

  • EROA = PISA (2πr2) * Valiasing / Vmax

Both the vena contracta measurement and the PISA method are the best methods to evaluate the severity of regurgitation[4] Tables 3 and 4.

Table 3. Aortic regurgitation (AR) severity. Semiquantitative parameters.[4]

Semiquantitative parameters Mild Moderate Severe
Vena contracta (cm) <0,3 Intermediate >0,6
Pressure half time (ms) >500 Intermediate <200


Table 4. AR severity. Qauntitative parameters.[4]

Quantitative parameters Mild Moderate Severe
EROA (mm2) <0,10 Intermediate >0,30
Regurgitant volume (ml) <30 Intermediate >0,60

Pulse wave doppler

Holodiastolic flow reversal in the descending aorta

Aortic reverse flow: An holodiastolic reverse flow suggests, at least, moderate aortic regurgitation. If diastole time-velocity integral is similar to systole is a feasible criteria of severity[3] Holodiastolic flow reversal in abdominal aorta has high sensitivity and specificity for severe aortic regurgitation.

Supportive Findings

By M-mode echocardiography, early mitral valve closure indicates increased left ventricle filling pressures and is often present in severe aortic regurgitation. An aortic regurgitation pressure half-time 200 ms indicates severity, otherwise, a pressure half-time >500 ms suggests mild aortic regurgitation (figure 3).

References

  1. Devlin WH, Petrusha J, Briesmiester K, Montgomery D, Starling MR Impact of vascular adaptation to chronic aortic regurgitation on left ventricular performance. Circulation. 1999;99(8):1027
  2. Roberts WC, Ko JM, Moore TR, Jones WH Causes of pure aortic regurgitation in patients having isolated aortic valve replacement at a single US tertiary hospital (1993 to 2005).Circulation. 2006;114(5):422
  3. 3.0 3.1 3.2 Morillo E. Enfermedad Valvular aórtica. Ecocardiografía: Cabrera. Madrid. Editorial Panamericana Médica S.A. 2011. 143-157
  4. 4.0 4.1 4.2 4.3 4.4 4.5 Patrizio Lancellotti (Chair), Christophe Tribouilloy , Andreas Hagendorff,Luis Moura4, Bogdan A. Popescu, Eustachio Agricola , Jean-Luc Monin,Luc A. Pierard1, Luigi Badano, and Jose L. Zamorano. European Association of Echocardiography recommendations for the assessment of valvular regurgitation. Part 1: aortic and pulmonary regurgitation (native valve disease). European Journal of Echocardiography (2010) 11, 223–244
  5. Roberts BJ, Grayburn PA. Color flow imaging of the vena contracta in mitralregurgitation: technical considerations. J Am Soc Echocardiogr 2003;16:1002–6
  6. Fehske W, Omran H, Manz M, Ko¨ hler J, Hagendorff A, Lu¨deritz B. Color-coded Doppler imaging of the vena contracta as a basis for quantification of pure mitral regurgitation. Am J Cardiol 1994;73:268–74
  7. Christophe M. Tribouilloy, Maurice Enriquez-Sarano et al. Assessment of Severity of Aortic Regurgitation Using the Width of the Vena Contracta: A Clinical Color Doppler Imaging Study. Circulation. 2000;102:558-564
  8. Raffi Bekeredjian and Paul A. Grayburn. Valvular Heart Disease : Aortic Regurgitation. Circulation. 2005;112:125-134
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