Normal Values

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Below an up-to-date list of echocardiographic normal values.

Contents

Left Ventricle

Left Ventricular Systolic Function

Reference limits and values and partition values of left ventricular function[1]
  Women Men
Reference range Mildly abnormal Moderately abnormal Severely abnormal Reference range Mildly abnormal Moderately abnormal Severely abnormal
Linear method
Endocardial fractional shortening, % 27–45 22–26 17–21 ≤16 25–43 20–24 15–19 ≤14
Midwall fractional shortening, % 15–23 13–14 11–12 ≤10 14–22 12–13 10–11 ≤10
2D Method
Ejection fraction, % ≥55 45–54 30–44 <30 ≥55 45–54 30–44 <30
  • 2D, Two-dimensional.
  • Green values: Recommended and best validated.

Left Ventricular Diastolic Function

Practical approach to LV diastolic function grading. Ater [2]


Normal values for Doppler-derived diastolic measurements[2]
  Age group (y)
Measurement 16-20 21-40 41-60 >60
IVRT (ms) 50 ± 9 (32-68) 67 ± 8 (51-83) 74 ± 7 (60-88) 87 ± 7 (73-101)
E/A ratio 1.88 ± 0.45 (0.98-2.78) 1.53 ± 0.40 (0.73-2.33) 1.28 ± 0.25 (0.78-1.78) 0.96 ± 0.18 (0.6-1.32)
DT (ms) 142 ± 19 (104-180) 166 ± 14 (138-194) 181 ± 19 (143-219) 200 ± 29 (142-258)
A duration (ms) 113 ± 17 (79-147) 127 ± 13 (101-153) 133 ± 13 (107-159) 138 ± 19 (100-176)
PV S/D ratio 0.82 ± 0.18 (0.46-1.18) 0.98 ± 0.32 (0.34-1.62) 1.21 ± 0.2 (0.81-1.61) 1.39 ± 0.47 (0.45-2.33)
PV Ar (cm/s) 16 ± 10 (1-36) 21 ± 8 (5-37) 23 ± 3 (17-29) 25 ± 9 (11-39)
PV Ar duration (ms) 66 ± 39 (1-144) 96 ± 33 (30-162) 112 ± 15 (82-142) 113 ± 30 (53-173)
Septal e´ (cm/s) 14.9 ± 2.4 (10.1-19.7) 15.5 ± 2.7 (10.1-20.9) 12.2 ± 2.3 (7.6-16.8) 10.4 ± 2.1 (6.2-14.6)
Septal e´/a´ ratio 2.4 1.6 ± 0.5 (0.6-2.6) 1.1 ± 0.3 (0.5-1.7) 0.85 ± 0.2 (0.45-1.25)
Lateral e´ (cm/s) 20.6 ± 3.8 (13-28.2) 19.8 ± 2.9 (14-25.6) 16.1 ± 2.3 (11.5-20.7) 12.9 ± 3.5 (5.9-19.9)
Lateral e´/a´ ratio 3.1 1.9 ± 0.6 (0.7-3.1) 1.5 ± 0.5 (0.5-2.5) 0.9 ± 0.4 (0.1-1.7)
  • Data are expressed as mean ± SD (95% confidence interval). Note that for e´ velocity in subjects aged 16 to 20 years, values overlap with those for subjects aged 21 to 40 years. This is because e´ increases progressively with age in children and adolescents. Therefore, the e´ velocity is higher in a normal 20-year-old than in a normal 16-year-old, which results in a somewhat lower average e´ value when subjects aged 16 to 20 years are considered.
  • Standard deviations are not included because these data were computed, not directly provided in the original articles from which they were derived.

Left Ventricular Mass and Geometry

Reference limits and partition values of left ventricular mass and geometry[1]
  Women Men
Reference
range
Mildly
abnormal
Moderately
abnormal
Severely
abnormal
Reference
range
Mildly
abnormal
Moderately
abnormal
Severely
abnormal
Linear Method
LV mass, g 67–162 163–186 187–210 ≥211 88–224 225–258 259–292 ≥293
LV mass/BSA, g/m2 43–95 96–108 109–121 ≥122 49–115 116–131 132–148 ≥149
LV mass/height, g/m 41–99 100–115 116–128 ≥129 52–126 127–144 145–162 ≥163
LV mass/height2, g/m2 18–44 45–51 52–58 ≥59 20–48 49–55 56–63 ≥64
Relative wall thickness, cm 0.22–0.42 0.43–0.47 0.48–0.52 ≥0.53 0.24–0.42 0.43–0.46 0.47–0.51 ≥0.52
Septal thickness, cm 0.6–0.9 1.0–1.2 1.3–1.5 ≥1.6 0.6–1.0 1.1–1.3 1.4–1.6 ≥1.7
Posterior wall thickness, cm 0.6–0.9 1.0–1.2 1.3–1.5 ≥1.6 0.6–1.0 1.1–1.3 1.4–1.6 ≥1.7
2D Method
LV mass, g 66–150 151–171 172–182 >193 96–200 201–227 228–254 >255
LV mass/BSA, g/m2 44–88 89–100 101–112 ≥113 50–102 103–116 117–130 ≥131
  • BSA, Body surface area; LV, left ventricular; 2D, 2-dimensional.
  • Green values: Recommended and best validated.

Left Ventricular Size

Reference limits and partition values of left ventricular size[1]
  Women Men
Reference
range
Mildly
abnormal
Moderately
abnormal
Severely
abnormal
Reference
range
Mildly
abnormal
Moderately
abnormal
Severely
abnormal
LV dimension
LV diastolic diameter 3.9–5.3 5.4–5.7 5.8–6.1 ≥6.2 4.2–5.9 6.0–6.3 6.4–6.8 ≥6.9
LV diastolic diameter/BSA, cm/m2 2.4–3.2 3.3–3.4 3.5–3.7 ≥3.8 2.2–3.1 3.2–3.4 3.5–3.6 ≥3.7
LV diastolic diameter/height, cm/m 2.5–3.2 3.3–3.4 3.5–3.6 ≥3.7 2.4–3.3 3.4–3.5 3.6–3.7 ≥3.8
LV volume
LV diastolic volume, mL 56–104 105–117 118–130 ≥131 67–155 156–178 179–201 ≥201
LV diastolic volume/BSA, mL/m2 35–75 76–86 87–96 ≥97 35–75 76–86 87–96 ≥97
LV systolic volume, mL 19–49 50–59 60–69 ≥70 22–58 59–70 71–82 ≥83
LV systolic volume/BSA, mL/m2 12–30 31–36 37–42 ≥43 12–30 31–36 37–42 ≥43
  • BSA, body surface area; LV, left ventricular.
  • Green values: Recommended and best validated.

Right Ventricle

Right Ventricular and Pulmonary Artery Size

Reference limits and partition values of right ventricular and pulmonary artery size[1]
  Reference range Mildly abnormal Moderately abnormal Severely abnormal
RV dimensions
Basal RV diameter (RVD 1), cm 2.0–2.8 2.9–3.3 3.4–3.8 ≥3.9
Mid-RV diameter (RVD 2), cm 2.7–3.3 3.4–3.7 3.8–4.1 ≥4.2
Base-to-apex length (RVD 3), cm 7.1–7.9 8.0–8.5 8.6–9.1 ≥9.2
RVOT diameters
Above aortic valve (RVOT 1), cm 2.5–2.9 3.0–3.2 3.3–3.5 ≥3.6
Above pulmonic valve (RVOT 2), cm 1.7–2.3 2.4–2.7 2.8–3.1 ≥3.2
PA diameter
Below pulmonic valve (PA 1), cm 1.5–2.1 2.2–2.5 2.6–2.9 ≥3.0
  • RV, Right ventricular; RVOT, right ventricular outflow tract; PA, pulmonary artery.
  • Data from Foale et al.[3]

Right Ventricular Size and Function

Reference limits and partition values of right ventricular size and function as measured in the apical 4-chamber view[1]
Reference range Mildly abnormal Moderately abnormal Severely abnormal
RV diastolic area, cm2 11–28 29–32 33–37 ≥38
RV systolic area, cm2 7.5–16 17–19 20–22 ≥23
RV fractional area change, % 32–60 25–31 18–24 ≤17
TAPSE, (cm) 1.5-2.0[1] 1.3-1.5[4] 1.0-1.2[4] <1.0[4]
  • RV, Right ventricular.
  • Data from Weyman.[5]

Atria

Left Atrial Dimensions / Volumes

Reference limits and partition values for left atrial dimensions/volumes[1]
  Women Men
Reference range Mildly abnormal Moderately abnormal Severely abnormal Reference range Mildly abnormal Moderately abnormal Severely abnormal
Atrial dimensions

LA diameter, cm 2.7–3.8 3.9–4.2 4.3–4.6 ≥4.7 3.0–4.0 4.1–4.6 4.7–5.2 ≥5.2
LA diameter/BSA, cm/m2 1.5–2.3 2.4–2.6 2.7–2.9 ≥3.0 1.5–2.3 2.4–2.6 2.7–2.9 ≥3.0
RA minor-axis dimension, cm 2.9–4.5 4.6–4.9 5.0–5.4 ≥5.5 2.9–4.5 4.6–4.9 5.0–5.4 ≥5.5
RA minor-axis dimension/BSA, cm/m2 1.7–2.5 2.6–2.8 2.9–3.1 ≥3.2 1.7–2.5 2.6–2.8 2.9–3.1 ≥3.2
Atrial area
LA area, cm2 ≤20 20–30 30–40 >40 ≤20 20–30 30–40 >40
Atrial volumes
LA volume, mL 22–52 53–62 63–72 ≥73 18–58 59–68 69–78 ≥79
LA volume/BSA, mL/m2 22 ± 6 29–33 34–39 ≥40 22 ± 6 29–33 34–39 ≥40
  • BSA, Body surface area; LA, left atrial; RA, right atrial.
  • Green values: Recommended and best validated.

Left Atrial Pressure

Estimation of left atrial pressure in normal LVEF. After [2]
Estimation of left atrial pressure in reduced LVEF. After [2]


Aortic Valve

Aortic valve stenosis - severity

Recommendations for classification of AS severity[6]
  Aortic sclerosis Mild Moderate Severe
Aortic jet velocity (m/s) ≤2.5 m/s 2.6-2.9 3.0-4.0 >4.0
Mean gradient (mmHg) - <20 (<30a) 20-40b (30-50a) >40b (>50a)
AVA (cm2) - >1.5 1.0-1.5 <1
Indexed AVA (cm2/m2)   >0.85 0.60-0.85 <0.6
Velocity ratio   >0.50 0.25-0.50 <0.25
  • aESC Guidelines.[7]
  • bAHA/ACC Guidelines.[8]

Aortic regurgitation - severity

Application of specific and supportive signs, and quantitative parameters in the grading of aortic regurgitation severity[9]
  Mild Moderate Severe
Specific signs for AR severity
  • Central Jet, width < 25% of LVOTς
  • Vena contracta < 0.3 cmς
  • No or brief early diastolic flow reversal in descending aorta
  • Signs of AR>mild present but no criteria for severe AR
  • Central Jet, width ≥ 65% of LVOTς
  • Vena contracta > 0.6cmς
Supportive signs
  • Pressure half-time > 500 ms
  • Normal LV size
  • Intermediate values
  • Pressure half-time < 200 ms
  • Holodiastolic aortic flow reversal in descending aorta
  • Moderate or greater LV enlargement∗∗
Quantitative parametersψ
R Vol, ml/beat < 30 30-44 45-59 ≥ 60
RF % < 30 30-39 40-49 ≥ 50
EROA, cm2 < 0.10 0.10-0.19 0.20-0.29 ≥ 0.30
  • AR, Aortic regurgitation; EROA, effective regurgitant orifice area; LV, left ventricle; LVOT, left ventricular outflow tract; R Vol, regurgitant volume; RF, regurgitant fraction.
  • LV size applied only to chronic lesions. Normal 2D measurements: LV minor-axis ≤ 2.8 cm/m2, LV end-diastolic volume ≤ 82 ml/m2 (2).
  • ς At a Nyquist limit of 50–60 cm/s.
  • ∗∗ In the absence of other etiologies of LV dilatation.
  • ψ Quantitative parameters can help sub-classify the moderate regurgitation group into mild-to-moderate and moderate-to-severe regurgitation as shown.


Mitral Valve

Mitral regurgitation - severity

Application of specific and supportive signs, and quantitative parameters in the grading of mitral regurgitation severity[9]
  Mild Moderate Severe
Specific signs of severity
  • Small central jet <4 cm2 or <20% of LA areaψ
  • Vena contracta width <0.3 cm
  • No or minimal flow convergence
  • Signs of MR>mild present, but no criteria for severe MR
  • Vena contracta width ≥ 0.7cm with large central MR jet (area < 40% of LA) or with a wall-impinging jet of any size, swirling in LAψ
  • Large flow convergenceς
  • Systolic reversal in pulmonary veins
  • Prominent flail MV leaflet or ruptured papillary muscle
Supportive signs
  • Systolic dominant flow in pulmonary veins
  • A-wave dominant mitral inflowΦ
  • Soft density, parabolic CW Doppler MR signal
  • Normal LV size
  • Intermediate signs/findings
  • Dense, triangular CW Doppler MR jet
  • E-wave dominant mitral inflow (E >1.2 m/s)Φ Enlarged LV and LA size∗∗, (particularly when normal LV function is present).
Quantitative parametersφ
R Vol (ml/beat) < 30 30-44 45-59 ≥ 60
RF (%) < 30 30-39 40-49 ≥ 50
EROA (cm2) < 0.20 0.20-0.29 0.30-0.39 ≥ 0.40
  • CW, Continuous wave; EROA, effective regurgitant orifice area; LA, left atrium; LV, left ventricle; MV, mitral valve; MR, mitral regurgitation; R Vol, regurgitant volume; RF, regurgitant fraction.
  • LV size applied only to chronic lesions. Normal 2D measurements: LV minor axis ≤ 2.8 cm/m2, LV end-diastolic volume ≤ 82 ml/m2, maximal LA antero-posterior diameter ≤ 2.8 cm/m2, maximal LA volume ≤ 36 ml/m2 (2;33;35).
  • ∗∗ In the absence of other etiologies of LV and LA dilatation and acute MR.
  • ψ At a Nyquist limit of 50-60 cm/s.
  • Φ Usually above 50 years of age or in conditions of impaired relaxation, in the absence of mitral stenosis or other causes of elevated LA pressure.
  • ς Minimal and large flow convergence defined as a flow convergence radius < 0.4 cm and ≤ 0.9 cm for central jets, respectively, with a baseline shift at a Nyquist of 40 cm/s; Cut-offs for eccentric jets are higher, and should be angle corrected (see text).
  • φ Quantitative parameters can help sub-classify the moderate regurgitation group into mild-to-moderate and moderate-to-severe as shown.

Mitral stenosis - severity

Recommendations for classification of mitral stenosis severity[6]
  Mild Moderate Severe
Specific findings
Valve area (cm2) >1.5 1.0-1.5 <1.0
Supportive findings
Mean gradient (mmHg)a <5 5-10 >10
Pulmonary artery pressure (mmHg) <30 30-50 >50
  • aAt heart rates between 60 and 80 bpm and in sinus rhythm.

Mitral valve stenosis - Wilkins score

Assessment of mitral valve anatomy according to the Wilkins score[10]
Grade Mobility Thickening Calcification Subvalvular Thickening
1 Highly mobile valve with only leaflet tips restricted Leaflets near normal in thickness (4-5 mm) A single area of increased echo brightness Minimal thickening just below the mitral leaflets
2 Leaflet mid and base portions have normal mobility Midleaflets normal, considerable thickening of margins (5-8 mm) Scattered areas of brightness confined to leaflet margins Thickening of chordal structures extending to one-third of the chordal length
3 Valve continues to move forward in diastole, mainly from the base Thickening extending through the entire leaflet (5-8mm) Brightness extending into the mid-portions of the leaflets Thickening extended to distal third of the chords
4 No or minimal forward movement of the leaflets in diastole Considerable thickening of all leaflet tissue (>8-10mm) Extensive brightness throughout much of the leaflet tissue Extensive thickening and shortening of all chordal structures extending down to the papillary muscles
  • The total score is the sum of the four items and ranges between 4 and 16.

Mitral stenosis - routine measurements

Recommendations for data recording and measurement in routine use for mitral stenosis quantitation[6]
Data element Recording Measurement
Planimetry
- 2D parasternal short-axis view - contour of the inner mitral orifice
- determine the smallest orifice by scanning from apex to base - include commissures when opened
- positioning of measurement plan can be oriented by 3D echo - in mid-diastole (use cine-loop)
- lowest gain setting to visualize the whole mitral orifice - average measurements if atrial fibrillation
Mitral flow
- continuous-wave Doppler - mean gradient from the traced contour of the diastolic mitral flow
- apical windows often suitable (optimize intercept angle) - pressure half-time from the descending sLope of the E-wave (mid-diastole slope if not linear)
- adjust gain setting to obtain well-defined flow contour - average measurements if atrial fibrillation
Systolic pulmonary artery pressure
- continuous-wave Doppler - maximum velocity of tricuspid regurgitant flow
- multiple acoustic windows to optimize intercept angle - estimation of right atrial pressure according to inferior vena cava diameter
Valve anatomy

- parasternal short-axis view

- valve thickness (maximum and heterogeneity)
- commissural fusion
- extension and location of localized bright zones (fibrous nodutes or calcification)

- parasternal long-axis view

- valve thickness
- extension of calcification
- valve pliability
- subvalvular apparatus (chordal thickening, fusion, or shortening)

- apical two-chamber view
- subvalvular apparatus (chordal thickening, fusion, or shortening)

Detail each component and summarize in a score


Tricuspid Valve

Tricuspid regurgitation - severity

Echocardiographic and Doppler parameters used in grading tricuspid regurgitation severity[9]
Parameter Mild Moderate Severe
Tricuspid valve Usually normal Normal or abnormal Abnormal/Flail leaflet/Poor coaptation
RV/RA/IVC size Normal Normal or dilated Usually dilated∗∗
Jet area-central jets (cm2)§ < 5 5-10 > 10
VC width (cm)Φ Not defined Not defined, but < 0.7 > 0.7
PISA radius (cm)ψ ≤ 0.5 0.6-0.9 > 0.9
Jet density and contour–CW Soft and parabolic Dense, variable contour Dense, triangular with early peaking
Hepatic vein flow† Systolic dominance Systolic blunting Systolic reversal
  • CW, Continuous wave Doppler; IVC, inferior vena cava; RA, right atrium; RV, right ventricle; VC, vena contracta width.
  • Unless there are other reasons for RA or RV dilation. Normal 2D measurements from the apical 4-chamber view: RV medio-lateral end-diastolic dimension ≤ 4.3 cm, RV end-diastolic area ≤ 35.5 cm2, maximal RA medio-lateral and supero-inferior dimensions ≤ 4.6 cm and 4.9 cm respectively, maximal RA volume ≤ 33 ml/m2(35;89).
  • ∗∗ Exception: acute TR.
  • § At a Nyquist limit of 50-60 cm/s. Not valid in eccentric jets. Jet area is not recommended as the sole parameter of TR severity due to its dependence on hemodynamic and technical factors.
  • Φ At a Nyquist limit of 50-60 cm/s.
  • ψ Baseline shift with Nyquist limit of 28 cm/s.
  • † Other conditions may cause systolic blunting (eg. atrial fibrillation, elevated RA pressure).

Tricuspid stenosis - severity

Findings indicative of haemodynamically significant tricuspid stenosis[6]
Specific findings
Mean pressure gradient ≥5 mmHg
Inflow time-velocity integral >60 cm
T1/2 ≥190 ms
Valve area by continuity equationa ≤1 cm2
Supportive findings
Enlarged right atrium ≥moderate
DHated inferior vena cava
  • aStroke volume derived from left or right ventricular outflow. In the presence of more than mild TR, the derived valve area will be underestimated. Nevertheless, a value ≤1 cm2 implies a significant haemodynamic burden imposed by the combined lesion.

Pulmonary Valve

Pulmonary regurgitaion - severity

Echocardiographic and Doppler parameters used in grading pulmonary regurgitation severity[9]
Parameter Mild Moderate Severe
Pulmonic valve Normal Normal or abnormal Abnormal
RV size Normal Normal or dilated Dilated
Jet size by color Doppler§ Thin (usually < 10 mm in length) with a narrow origin Intermediate Usually large, with a wide origin; May be brief in duration
Jet density and deceleration rate –CW† Soft; Slow deceleration Dense; variable deceleration Dense; steep deceleration, early termination of diastolic flow
Pulmonic systolic flow compared to systemic flow –PWφ Slightly increased Intermediate Greatly increased
  • CW, Continuous wave Doppler; PR, pulmonic regurgitation; PW, pulsed wave Doppler; RA, right atrium; RF, regurgitant fraction; RV, right ventricle.
  • Unless there are other reasons for RV enlargement. Normal 2D measurements from the apical 4-chamber view; RV medio-lateral end-diastolic dimension ≤ 4.3 cm, RV end-diastolic area ≤ 35.5 cm2(89).
  • ∗∗ Exception: acute PR
  • § At a Nyquist limit of 50-60 cm/s.
  • φ Cut-off values for regurgitant volume and fraction are not well validated.
  • † Steep deceleration is not specific for severe PR.

Pulmonary stenosis - severity

Grading of pulmonary stenosis[6]
  Mild Moderate Severe
Peak velocity (m/s) <3 3-4 >4
Peak gradient (mmHg) <36 36-64 >64


References

Click on the reference to link directly to the manuscript

  1. Lang RM, Bierig M, Devereux RB, Flachskampf FA, Foster E, Pellikka PA, Picard MH, Roman MJ, Seward J, Shanewise J, Solomon S, Spencer KT, St John Sutton M, and Stewart W. Recommendations for chamber quantification. Eur J Echocardiogr 2006 Mar; 7(2) 79-108. doi:10.1016/j.euje.2005.12.014 pmid:16458610. PubMed
  2. Nagueh SF, Appleton CP, Gillebert TC, Marino PN, Oh JK, Smiseth OA, Waggoner AD, Flachskampf FA, Pellikka PA, and Evangelista A. Recommendations for the evaluation of left ventricular diastolic function by echocardiography. J Am Soc Echocardiogr 2009 Feb; 22(2) 107-33. doi:10.1016/j.echo.2008.11.023 pmid:19187853. PubMed
  3. Foale R, Nihoyannopoulos P, McKenna W, Kleinebenne A, Nadazdin A, Rowland E, and Smith G. Echocardiographic measurement of the normal adult right ventricle. Br Heart J 1986 Jul; 56(1) 33-44. pmid:3730205. PubMed
  4. isbn:9031362352.
  5. Arthur E. Weyman. Principles and practice of echocardiography. Philadelphia: Lea & Febiger, 1994. isbn:0812112075.
  6. Baumgartner H, Hung J, Bermejo J, Chambers JB, Evangelista A, Griffin BP, Iung B, Otto CM, Pellikka PA, and Quiñones M. Echocardiographic assessment of valve stenosis: EAE/ASE recommendations for clinical practice. J Am Soc Echocardiogr 2009 Jan; 22(1) 1-23; quiz 101-2. doi:10.1016/j.echo.2008.11.029 pmid:19130998. PubMed
  7. Vahanian A, Baumgartner H, Bax J, Butchart E, Dion R, Filippatos G, Flachskampf F, Hall R, Iung B, Kasprzak J, Nataf P, Tornos P, Torracca L, and Wenink A. Guidelines on the management of valvular heart disease: The Task Force on the Management of Valvular Heart Disease of the European Society of Cardiology. Eur Heart J 2007 Jan; 28(2) 230-68. doi:10.1093/eurheartj/ehl428 pmid:17259184. PubMed
  8. Zoghbi WA, Enriquez-Sarano M, Foster E, Grayburn PA, Kraft CD, Levine RA, Nihoyannopoulos P, Otto CM, Quinones MA, Rakowski H, Stewart WJ, Waggoner A, and Weissman NJ. Recommendations for evaluation of the severity of native valvular regurgitation with two-dimensional and Doppler echocardiography. J Am Soc Echocardiogr 2003 Jul; 16(7) 777-802. doi:10.1016/S0894-7317(03)00335-3 pmid:12835667. PubMed
  9. Wilkins GT, Weyman AE, Abascal VM, Block PC, and Palacios IF. Percutaneous balloon dilatation of the mitral valve: an analysis of echocardiographic variables related to outcome and the mechanism of dilatation. Br Heart J 1988 Oct; 60(4) 299-308. pmid:3190958. PubMed
  10. Bonow RO, Carabello BA, Chatterjee K, de Leon AC Jr, Faxon DP, Freed MD, Gaasch WH, Lytle BW, Nishimura RA, O'Gara PT, O'Rourke RA, Otto CM, Shah PM, and Shanewise JS. 2008 focused update incorporated into the ACC/AHA 2006 guidelines for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to revise the 1998 guidelines for the management of patients with valvular heart disease). Endorsed by the Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. J Am Coll Cardiol 2008 Sep 23; 52(13) e1-142. doi:10.1016/j.jacc.2008.05.007 pmid:18848134. PubMed