Diastolic dysfunction echocardiography
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Echocardiography
Correlates of Left ventricle diastolic dysfunction
- Left ventricular mass and/or thickness- The left ventricular mass is difficult to measure with 3-dimensional echocardiography [1]. 2-dimensional echocardiography can also be used to assess atleast the wall thickness (wall thickness is increased in both hypertrophy and remodelling)[2].
- Left atrial volume- Highly reliable and best measured using 4-chamber and 2-chamber views[2]. It is clinically relevant as this is reflection of the extent of left ventricular remodelling over time[3]. An index of 34 ml/m2 is considered as an independent predictor death, heart failure, atrial fibrillation, and ischemic stroke[4]. Dilated left atrial volume is however not exclusive to diastolic dysfunction. Other conditions like high output states, bradycardia and 4-chamber enlargement, atrial flutter or atrial fibrillation, mitral valve disease and in few cases of athletes. It is vital therefore to differentiate on clinical basis, other echo volumes etc.
- Left atrial function- The reservoir, conduit, and stroke volumes of the left atrium can be computed and expressed as percentages of LA stroke volume[5]. The systolic function of left atrium (which contributes to filling in late diastole) is assessed using a combination of 2D and Doppler[6][7]. It can be measured as follows-
- LA ejection force (0.5 X 1.06 X Mitral annular area X [Peak A velocity]2]) and,
- Kinetic energy (0.5 X 1.06 X LA stroke volume X [A velocity]2)
- Patients with diastolic dysfunction have increased pulmonary artery pressures. Derivation of the PA systolic pressure is made using peak velocity of the tricuspid regurgitation (TR) jet and systolic right atrial pressure by continuous wave (CW) Doppler[8]. The end-diastolic velocity of pulmonary regurgitation (PR) jet can be applied to derive PA diastolic pressure[8]. PA diastolic pressure by Doppler echocardiography correlates well with mean pulmonary wedge pressure and may be used as its surrogate[9] but the assumption is not true in every case.
Mitral inflow
- Pulsed wave Doppler is performed in the apical 4-chamber view to obtain mitral inflow velocities to assess LV filling.
- A 1-mm to 3-mm sample volume is then placed between the mitral leaflet tips during diastole to record a crisp velocity profile.
- Primary measurements include peak E (early diastolic) and A (late diastolic) velocities, E/A ratio, deceleration time (DT), and isovolumic relaxation time (IVRT).
- Mitral inflow patterns could include normal, impaired LV relaxation, pseudonormal left ventricle filling (PNF), and restrictive LV filling.
- In patients with dilated cardiomyopathies, filling patterns correlate better with filling pressures, functional class, and prognosis than LV ejection fraction (EF).
- In patients with coronary artery disease and those with hypertrophic cardiomyopathy in whom the LV EFs are >50%, mitral velocities correlate poorly with hemodynamics.
Valsalva maneuver
- The Valsalva maneuver is performed by forceful expiration against a closed nose and mouth. In cardiac patients, a decrease of >50% in the E/A ratio is highly specific for increased LV filling pressures[10], but a smaller magnitude of change does not always indicate normal diastolic function.
Shown below is an image demonstrating the changes in the E/A ratio and deceleration time (DT) with varying degrees of diastolic dysfunction. The parameters measured to assess left ventricular filling are mitral inflow and the same with peak Valsalva maneuver.
Pulmonary venous flow
- Pulsed wave Doppler of pulmonary venous flow is performed in the apical 4-chamber view and aids in the assessment of LV diastolic function.
- A 2-mm to 3-mm sample volume is placed <0.5 cm into the pulmonary vein for optimal recording of the spectral waveforms.
- Measurements include peak S (systolic) and D (anterograde diastolic) velocities, the S/D ratio, systolic filling fraction (S time-velocity intergral/S time-velocity integral + D time-velocity integral), and peak Ar velocity in late diastole. Another measurement is the time difference between Ar duration and mitral A-wave duration (Ar-A).
- With increased left ventricular end diastolic pressure (LVEDP), Ar velocity and duration increase, as well as the Ar-A duration.
- In patients with depressed EFs, reduced systolic filling fractions (40%) are related to decreased LA compliance and increased mean LA pressure.
Color M-Mode flow propagation velocity
- Acquisition is performed in the apical 4-chamber view, using color flow imaging.
- Flow propagation velocity (Vp) of 50 cm/s is considered normal.
- In most patients with depressed EFs, Vp is reduced, and if other Doppler indices appear inconclusive, an E/Vp ratio of >2.5 can predict a PCWP >15 mm Hg with reasonable accuracy.
- Patients with normal LV volumes and EFs but elevated filling pressures can have normal Vp.
Tissue Doppler annular early and late diastolic velocities
- Pulsed wave tissue Doppler imaging (DTI) is performed in the apical views to acquire mitral annular velocities.
- Primary measurements include the systolic and early (é) and late (á) diastolic velocities.
- In patients with cardiac disease, é can be used to correct for the effect of LV relaxation on mitral E velocity, and the E/é ratio can be applied for the prediction of LV filling pressures.
- The E/é ratio is not accurate as an index of filling pressures in normal subjects or in patients with heavy annular calcification, mitral valve disease, and constrictive pericarditis.
Deformation measurements
The reliability of deformation imaging to assess diastolic dysfunction has been researched and though it seems promising, more studies are needed in this area. Doppler flow velocity and myocardial velocity imaging remain initial methods for assessing diastolic dysfunction. In clinical cardiology, strain means deformation. It is most often expressed as a percentage or a fraction (Lagrangian strain). Myocardial strain and strain rate are good parameters.
Left ventricular untwisting
Similarly as for deformation imaging, measurements of left ventricle twist and untwisting rate has not been recommended since further studies are needed to prove its reliability.
Estimation of left ventricular relaxation
- IVRT by itself has limited accuracy, given the confounding influence of preload on it, which opposes the effect of impaired LV relaxation.
- Most patients with é (lateral) <8.5 cm/s or é (septal) <8 cm/s have impaired myocardial relaxation.
- Vp is most reliable as an index of LV relaxation in patients with depressed EFs and dilated left ventricles.
- For research purposes, mitral and aortic regurgitation signals by continuous wave (CW) Doppler can be used to derive ţ ( IVRT/[ln LV end-systolic pressure - ln LA pressure] )
Left ventricular wall stiffness
To compute the LV chamber stiffness constant, the diastolic pressure volume curves need to be derived from the pressure recordings and mitral inflow[11][12]. The estimation of end-diastolic compliance (reciprocal of LV stiffness) is not reliable in case of advanced diastolic dysfunction.
Mitral deceleration time is inversely proportional to square root of LV stiffness. It can be calculated as - KLV= [70ms/(DT - 20ms)]2.[13][14] and can be considered. Another parameter that can be used is A-wave transit time measured using PW Doppler echocardiography. This time interval relates well to late diastolic stiffness[15][16].
Diastolic stress test
In cases of normal myocardial relaxation, E and é velocities increase proportionally with exercise and the E/é ratio remains unchanged or is reduced. However, in patients with impaired myocardial relaxation, the increase in é with exercise is much less than that of mitral E velocity, such that the E/é ratio increases. The test is most useful in patients with unexplained exertional dyspnea who have mild diastolic dysfunction and normal filling pressures at rest. However, sufficient clinical data is not available and its not recommended in clinical practice.
References
- ↑ Hung J, Lang R, Flachskampf F, Shernan SK, McCulloch ML, Adams DB; et al. (2007). "3D echocardiography: a review of the current status and future directions". J Am Soc Echocardiogr. 20 (3): 213–33. doi:10.1016/j.echo.2007.01.010. PMID 17336747.
- ↑ 2.0 2.1 Lang RM, Bierig M, Devereux RB, Flachskampf FA, Foster E, Pellikka PA; et al. (2006). "Recommendations for chamber quantification". Eur J Echocardiogr. 7 (2): 79–108. doi:10.1016/j.euje.2005.12.014. PMID 16458610.
- ↑ Tsang TS, Barnes ME, Gersh BJ, Bailey KR, Seward JB (2002). "Left atrial volume as a morphophysiologic expression of left ventricular diastolic dysfunction and relation to cardiovascular risk burden". Am J Cardiol. 90 (12): 1284–9. PMID 12480035.
- ↑ Abhayaratna WP, Seward JB, Appleton CP, Douglas PS, Oh JK, Tajik AJ; et al. (2006). "Left atrial size: physiologic determinants and clinical applications". J Am Coll Cardiol. 47 (12): 2357–63. doi:10.1016/j.jacc.2006.02.048. PMID 16781359.
- ↑ Prioli A, Marino P, Lanzoni L, Zardini P (1998). "Increasing degrees of left ventricular filling impairment modulate left atrial function in humans". Am J Cardiol. 82 (6): 756–61. PMID 9761086.
- ↑ Manning WJ, Silverman DI, Katz SE, Douglas PS (1993). "Atrial ejection force: a noninvasive assessment of atrial systolic function". J Am Coll Cardiol. 22 (1): 221–5. PMID 8509545.
- ↑ Stefanadis C, Dernellis J, Lambrou S, Toutouzas P (1998). "Left atrial energy in normal subjects, in patients with symptomatic mitral stenosis, and in patients with advanced heart failure". Am J Cardiol. 82 (10): 1220–3. PMID 9832098.
- ↑ 8.0 8.1 Quiñones MA, Otto CM, Stoddard M, Waggoner A, Zoghbi WA, Doppler Quantification Task Force of the Nomenclature and Standards Committee of the American Society of Echocardiography (2002). "Recommendations for quantification of Doppler echocardiography: a report from the Doppler Quantification Task Force of the Nomenclature and Standards Committee of the American Society of Echocardiography". J Am Soc Echocardiogr. 15 (2): 167–84. PMID 11836492.
- ↑ Lee RT, Lord CP, Plappert T, Sutton MS (1989). "Prospective Doppler echocardiographic evaluation of pulmonary artery diastolic pressure in the medical intensive care unit". Am J Cardiol. 64 (19): 1366–70. PMID 2589205.
- ↑ Hurrell DG, Nishimura RA, Ilstrup DM, Appleton CP (1997). "Utility of preload alteration in assessment of left ventricular filling pressure by Doppler echocardiography: a simultaneous catheterization and Doppler echocardiographic study". J Am Coll Cardiol. 30 (2): 459–67. PMID 9247519.
- ↑ Zile MR, Baicu CF, Gaasch WH (2004). "Diastolic heart failure--abnormalities in active relaxation and passive stiffness of the left ventricle". N Engl J Med. 350 (19): 1953–9. doi:10.1056/NEJMoa032566. PMID 15128895.
- ↑ Gorcsan J, Gasior TA, Mandarino WA, Deneault LG, Hattler BG, Pinsky MR (1994). "Assessment of the immediate effects of cardiopulmonary bypass on left ventricular performance by on-line pressure-area relations". Circulation. 89 (1): 180–90. PMID 8281645.
- ↑ Garcia MJ, Firstenberg MS, Greenberg NL, Smedira N, Rodriguez L, Prior D; et al. (2001). "Estimation of left ventricular operating stiffness from Doppler early filling deceleration time in humans". Am J Physiol Heart Circ Physiol. 280 (2): H554–61. PMID 11158951.
- ↑ Marino P, Little WC, Rossi A, Barbieri E, Anselmi M, Destro G; et al. (2002). "Can left ventricular diastolic stiffness be measured noninvasively?". J Am Soc Echocardiogr. 15 (9): 935–43. PMID 12221410.
- ↑ Pai RG, Suzuki M, Heywood JT, Ferry DR, Shah PM (1994). "Mitral A velocity wave transit time to the outflow tract as a measure of left ventricular diastolic stiffness. Hemodynamic correlations in patients with coronary artery disease". Circulation. 89 (2): 553–7. PMID 8313543.
- ↑ Pai RG, Varadarajan P (2004). "Relative duration of transmitted mitral A wave as a measure of left ventricular end-diastolic pressure and stiffness". Echocardiography. 21 (1): 27–31. PMID 14717717.