Doppler echocardiography and myocardial dyssynchrony: a practical update of old and new ultrasound technologies
© Galderisi et al; licensee BioMed Central Ltd. 2007
Received: 09 August 2007
Accepted: 06 September 2007
Published: 06 September 2007
Morbidity and mortality rates are higher in patients with severe left ventricular (LV) systolic dysfunction and ECG-derived prolonged QRS interval than in those with normal QRS duration. QRS duration is currently used on the grounds that it reflects the presence of ventricular dyssynchrony. However, 30–40% of patients selected on the basis of a prolonged QRS do not receive benefit by cardiac resynchronization therapy (CRT) since they do not show any significant inverse LV remodeling and QRS duration does not accurately distinguish responders to CRT. Consequently, mechanical dyssynchrony (particularly intra-ventricular dyssynchrony) seems to be much more important than electrical dyssinchrony. Pre- and post-echocardiographic assessment should require the combination of conventional and specific applications ranging from M-mode and pulsed/continuous Doppler, to pulsed Tissue Doppler, the off-line analysis of colour Tissue Velocity Imaging, Strain Rate Imaging, and real time three-dimensional reconstruction However, there is not no consensus about the best approach and the best ultrasound parameter for selecting candidates to CRT and ECG representation of abnormal cardiac conduction still remains as the main criterion in guidelines. This review is a practical update of ultrasound methods and measurements of atrio-ventricular, inter-ventricular and intra-ventricular dyssynchrony and describes experiences which used either conventional Doppler echocardiography and more advanced techniques. By these experiences, the global amount of LV dyssynchrony seems to be critical: the greater intra-ventricular dyssynchrony, the higher the possibility of significant LV inverse remodeling. After CRT, it is necessary also to evaluate the optimal atrio-ventricular delay and ventricular-ventricular delay setting that maximizes LV systolic function.
Morbidity and mortality rates are higher in patients with severe left ventricular (LV) systolic dysfunction and ECG-derived prolonged QRS interval than in those with normal QRS duration . Bi-Ventricular Pacing (BIVP) and Cardiac Resynchronization Therapy (CRT) have become additional treatment aimed to synchronizing biventricular activation and contraction in patients with severe chronic heart failure (CHF) associated with interventricular conduction delay. CRT is effective in improving functional capacity and degree of secondary mitral regurgitation [2–4] and, above all, in reducing the mortality in cases of refractory CHF. NYHA classes III-IV, a LV ejection fraction (EF) of ≤ 35%, a LV end-diastolic diameter > 30 mm/m2 and a surface ECG derived QRS duration > 120 ms, together with a need for maximal pharmacological therapy, are considered from guidelines to select patients for CRT .
QRS duration is currently used on the grounds that it reflects the presence of ventricular dyssynchrony. However, 30–40% of patients selected on the basis of a prolonged QRS do not receive benefit by CRT since they do not show any significant inverse LV remodeling (a ≥ 15% reduction of LV end-systolic volume six months after device implantation) [6, 7]. Furthermore, QRS duration does not accurately distinguish responders to CRT . Although factors responsible for the absence of favourable response may be lead dislodgement or inappropriate location of LV lead, mechanical dyssynchrony (particularly intra-ventricular dyssynchrony) seems to be much more important than electrical dyssinchrony, and Doppler echocardiography should be widely used before and after implantation of a CRT device [9, 10].
Pre- and post-echocardiographic assessment includes conventional and/or specific applications ranging from M-mode and pulsed/continuous Doppler, to pulsed Tissue Doppler, the off-line analysis of colour Tissue Doppler, Strain Rate Imaging (SRI), and real time 3-D reconstruction [9–13]. The different modalities of the transthoracic ultrasound approach are able to identify the 3 different kinds of mechanical dyssynchrony: 1. Atrio-ventricular dyssinchrony, 2. Inter-ventricular dyssynchrony, 3. Intra-ventricular dyssynchrony.
1. Atrio-ventricular dyssynchrony
2. Inter-ventricular dyssynchrony
Alternatively, pulsed Tissue Doppler can be used to determine IVMD by measuring the time from QRS onset to the peak myocardial systolic velocities (Sm) of the RV free wall (tricuspid annulus) versus the same time of LV lateral mitral annulus (apical 4-chamber view) .
It is important to state that intraventricular dyssynchrony does not correlate with reverse LV remodeling after CRT, even when data from patients with and without coronary artery disease are evaluated separately [17–19].
3. Intra-ventricular mechanical dyssynchrony
Intra-ventricular dyssynchrony is characterized by either premature or late contraction of LV wall segments due to delayed electrical conduction . It can be identified by means of simple M-mode, pulsed Tissue Doppler, or, better, by colour Tissue Velocity Imaging (TVI), SRI and 3-D echocardiography.
Pulsed (PW) Tissue Doppler
Extensions of these method have been proposed by recording 2D imaging in the 4- 2- and 5-chamber apical views, in order to place PW Tissue Doppler sample volume in a specific myocardial segment and to measure Q to peak Sm and/or Q to Sm onset in various LV segments. The number of LV segments to be evaluated include mainly a 12-segment model (LV basal and middle segments in 4-, 2- and 5-chamber views) whereas LV apical segments are not considered reliable because of the basal-apical myocardial gradient own of Tissue Doppler. Technical refinements include the need to set the velocity scale of PW Tissue Doppler to display spectral velocities of 20 cm/s above and below the zero baseline because myocardial motion is characterized by low velocities. Spectral Doppler gain must be usually reduced, wall filters adjusted and spectral velocities recorded at sweep speed of 100 mm/s (during held respiratory expiration), in order to obtain the clearest delineation of Sm onset and peak. Electromechanical delay has to be averaged over at least 3 cardiac cycles. The main limitation of PW Tissue Doppler corresponds to the impossibility of measuring the time intervals of different segments during the same cardiac cycle. It is also necessary to take into account that the Sm recorded in apical views reflects LV longitudinal shortening and not circumferential contraction.
Colour Tissue Doppler
TSI is an implementation of Ts method. It displays Ts in multiple LV segments by colour coding wall motion green (corresponding to early systolic contraction) or red, which corresponds to delayed contraction (sensitivity = 87%, specificity = 81% and accuracy = 84% at a cut-off value of 34.4 ms in 56 patients with severe heart failure) .
It is important to point out that all colour Tissue Doppler derived techniques require high 2-D frames rates (>90 frames/s)  and that 2-D image should be optimized with a narrow sector width that includes the basal and middle segments of opposite LV walls and depth setting that include left ventricle, mitral annulus and the base of the left atrium . Colour Tissue Doppler gain has to be adjusted in order to display myocardial motion clearly. At least 3 cardiac cycles should be recorded during held respiration. Before performing measurements, aortic valve opening (= AVO) and AVC must be marked by means of a previous recorded PW Doppler of LV outflow tract, in order to avoid confusion between systolic (normal) and post-systolic (abnormal) contraction .
The 2-D strain (speckle tracking) technique has very recently been used to assess radial dyssynchrony before/after CRT. Speckle tracking has been applied to routine mid-ventricular short-axis images to calculate radial strain from multiple circumferential points averaged to six standard segments and dyssynchrony from timing of peak radial strain has been demonstrated to be correlated with Tissue Doppler measures in 47 subjects . A time difference ≥ 130 ms between the radial strain peak of LV posterior wall and anterior septum has shown to be highly predictive of an improved EF during follow-up, with 89% sensitivity and 83% specificity .
What to measure before and after CRT
Main ultrasound techniques, parameters and reference values for detection of intra-ventricular dyssynchrony and prediction of LV reverse remodeling.
Pitzalis et al, J Am Coll Cardiol 2002
> 130 ms
M-mode and PW Doppler
Sassone et al, Am J Cardiol 2007
PW Tissue Doppler
Diff. of Ts between LV segments
Bax JJ et al, J Am Coll Cardiol 2004
> 65 ms
Yu et al, Am J Cardiol 2003
> 32.6 ms
Yu et al, J Am Coll Cardiol 2005
> 34.4 ms
Mele et al, Eur Heart J 2006
> 60 ms
Porciani MC et al, Eur Heart J 2006
> 760 ms
2D radial strain
Time diff. in peak septal wall-to-posterior wall strain
Suffoletto et al, Circulation 2006
≥ 130 ms
Van der Veire NR et al, Am J Cardiol 2007
≥ 35.8 *
Sensitivity, specificity and accuracy, and confirmatory or conflicting data of the main ultrasound techniques presented in Table 1.
M-mode and PW Doppler
Diff. of Ts between LV segments
2D radial strain
Time diff. peak septal-to-posterior wall strain
Although several studies have demonstrated the superiority of ultrasound over QRS duration to assess LV dyssynchrony, there are no conclusive data on prediction of CRT response either using conventional or more advanced echocardiographic technologies. The Cardiac Resynchronization-Heart Failure (CARE-HF) study is the only large randomized and controlled trial that required direct, ultrasound measurement of cardiac dyssynchrony in a subset of patients with mild to moderate QRS enlargement (= 120–149 ms) (5). However, in the CARE-HF study only 92 patients (11%) underwent CRT based on Doppler echocardiographic indexes of myocardial dyssynchrony. Of consequence, the results cannot be considered exhaustive. It is not unexpected, therefore, that the ECG representation of abnormal cardiac conduction still remains as the main criterion to identify patients with dyssynchronous ventricular contraction. Accordingly, no consensus definition of cardiac dyssynchrony exists as yet from the main cardiologic associations [44–47], although several of the mentioned echocardiographic measures appear very promising
- Iuliano S, Fisher SG, Karasik PE, Fletcher RD, Singh SN: Department of Veterans Affairs Survival Trial of Antiarrhythmic Therapy in Congestive Heart Failure. QRS duration and mortality in patients. Am Heart J 2002, 143: 1085-1091. 10.1067/mhj.2002.122516View ArticlePubMedGoogle Scholar
- Blanc JJ, Etienne Y, Gilard M, Mansourati J, Munier S, Boschat J, Benditt DG, Lurie KG: Evaluation of different ventricular pacing sites in patients with severe heart failure: results of an acute hemodynamic study. Circulation 1997, 96: 3273-3277.View ArticlePubMedGoogle Scholar
- Kass DA, Chen CH, Curry C, Talbot M, Berger R, Fetics B, Nevo E: Improved left ventricular mechanics from acute VDD pacing in patients with dilated cardiomyopathy and ventricular conduction delay. Circulation 1999, 99: 1567-1573.View ArticlePubMedGoogle Scholar
- Toussaint JF, Lavergne T, Ollitraut J, Hignette C, Darondel JM, De Dieuleveult B, Froissart M, Le Heuzey JY, Guize L, Paillard M: Biventricular pacing in severe heart failure patients reverses electromechanical dyssynchronization from apex to base. Pacing Clin Electrophysio 2000, 23: 1731-1734.View ArticleGoogle Scholar
- Cleland JG, Daubert JC, Erdmann E, Freemantle N, Gras D, Kappenberg L, Tavazzi L: Cardiac Resynchronization – Heart Failure (CARE-HF) Investigators. The effect of cardiac resynchronization therapy on morbidity and mortality in heart failure. N Engl J Ned 2005, 352: 1539-1549. 10.1056/NEJMoa050496View ArticleGoogle Scholar
- Gregoratos G, Abrams J, Epstein AE, Freedman RA, Hayes DL, Hlatky MA, Kerber RE, Naccarelli GV, Schoenfeld MH, Silka MJ, Winters SL: ACC/AHA/NASPE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices – summary article: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (ACC/AHA/NASPE Committee to Update the 1998 Pacemaker Guidelines). J Am Coll Cardiol 2002, 40: 1703-1719. 10.1016/S0735-1097(02)02528-7View ArticlePubMedGoogle Scholar
- Abraham WT, Hayes DL: Cardiac resynchronization therapy for heart failure. Circulation 2003, 108: 1500-1506. 10.1161/01.CIR.0000096580.26969.9AView ArticleGoogle Scholar
- Lecoq G, Leclercq C, Leray E, Crocq C, Alonso C, de Place C, Mabo P, Daubert C: Clinical and electrocardiographic predictors of a positive response to cardiac resynchronization therapy in advanced heart failure. Eur Heart J 2005, 26: 1094-1100. 10.1093/eurheartj/ehi146View ArticlePubMedGoogle Scholar
- Bax JJ, Ansalone G, Breithardt OA, Derumeaux G, Leclercq C, Schalij MJ, Sogaard P, St John Sutton M, Nihoyannopoulos P: Echocardiographic evaluation of cardiac resynchronization therapy: ready for routine clinical use? A critical appraisal. J Am Coll Cardiol 2004, 44: 1-9. 10.1016/j.jacc.2004.02.055View ArticlePubMedGoogle Scholar
- Saxon LA, De Marco T, Schafer J, Chatterjee K, Kumar UN, Foster E: VIGOR Congestive Heart Failure Investigators. Cardiomyopathy and Arrhythmia Research and Education effects of long-term biventricular stimulation for resynchronization on echocardiographic measures of remodeling. Circulation 2002, 105: 1304-1310. 10.1161/hc1102.105730View ArticlePubMedGoogle Scholar
- Waggoner AD, Agler DA, Adamds DB: Cardiac resynchronization therapy and the emerging role of echocardiography (Part 1): indications and results from current studies. J Am Soc Echocardiogr 2007, 20: 70-75. 10.1016/j.echo.2005.10.021View ArticlePubMedGoogle Scholar
- Agler DA, Adams DB, Waggoner AD: Cardiac resynchronization therapy and the emerging role of echocardiography (Part 2); the comprehensive examination. J Am Soc 2007, 20: 76-90.Google Scholar
- Bax JJ, Abraham T, Barold SS, Breithardt OA, Fung JW, Garrigue S, Gorcsan J, Hayes DL, Kass DA, Knuuti J, Leclercq C, Linde C, Mark DB, Monaghan MJ, Nihoyannopoulos P, Schalij MJ, Stellbrink C, Yu CM: Cardiac resynchronization therapy: Part I. Issues before device implantation. J Am Coll Cardiol 2005, 46: 2153-2167. 10.1016/j.jacc.2005.09.019View ArticlePubMedGoogle Scholar
- Nishimura RA, Hayes DL, Holmes SR, Tajik AJ: Mechanism of hemodynamic improvement by dual-chamber pacing for severe left ventricular dysfunction: an acute Doppler and catheterization hemodynamic study. J Am Col Cardiol 1995, 25: 281-288. 10.1016/0735-1097(94)00419-QView ArticleGoogle Scholar
- Jansen AH, Bracke FA, van Dantzig JM, Meijer A, van der Voort PH, Aarnoudse W, van Gelder BM, Peels KH: Correlation of echo-Doppler optimization of atrio-ventricular delay in cardiac resynchronization therapy with invasive hemodynamics in patients with heart failure secondary to ischemic or idiopathic dilated cardiomyopathy. Am J Cardiol 2006, 97: 552-557. 10.1016/j.amjcard.2005.08.076View ArticlePubMedGoogle Scholar
- Cazeau S, Bordachar P, Jauvert G, Lazarus A, Alonso C, Vandrell MC, Mugica J, Ritter P: Echocardiographic modeling of cardiac dyssynchrony before and during multisite stimulation: a prospective study. Pacing Clin Electrophysiol 2003, 26: 137-143. 10.1046/j.1460-9592.2003.00003.xView ArticlePubMedGoogle Scholar
- Bader H, Garrigue S, Lafitte S, Reuter S, Jaïs P, Haïssaguerre M, Bonnet J, Clementy J, Roudaut R: Intra-left ventricular electromechanical asynchrony. A new independent predictor of severe cardiac events in heart failure patients. J Am Coll Cardiol 2004, 43: 248-256. 10.1016/j.jacc.2003.08.038View ArticlePubMedGoogle Scholar
- Bordachar P, Lafitte S, Reuter S, Sanders P, Jaïs P, Haïssaguerre M, Roudaut R, Garrigue S, Clementy J: Echocardiographic parameters of ventricular dyssynchrony validation in patients with heart failure using sequential biventricular pacing. J Am Coll Cardiol 2004, 44: 2157-2165. 10.1016/j.jacc.2004.08.065View ArticlePubMedGoogle Scholar
- Bax JJ, Bleeker GB, Marwick TH, Molhoek SG, Boersma E, Steendijk P, van der Wall EE, Schalij MJ: Left ventricular dyssynchrony predicts response and prognosis after cardiac resynchronization therapy. J Am Coll Cardiol 2004, 44: 1834-1840. 10.1016/j.jacc.2004.08.016View ArticlePubMedGoogle Scholar
- Prinzen FW, Augustijn CH, Arts T, Allessie MA, Reneman RS: Redistribution of myocardial fiber strain and blood flow by asynchronous activation. Am J Physiol 1990, 259: H300-H308.PubMedGoogle Scholar
- Pitzalis MV, Iacoviello M, Romito R, Massari F, Rizzon B, Luzzi G, Guida P, Andriani A, Mastropasqua F, Rizzon P: Cardiac resynchronization therapy tailored by echocardiographic evaluation of ventricular asynchrony. J Am Coll Cardiol 2002, 40: 1616-1622. 10.1016/S0735-1097(02)02337-9View ArticleGoogle Scholar
- Pitzalis MV, Iacoviello M, Romito R, Guida P, De Tommasi E, Luzzi G, Anaclerio M, Forleo C, Rizzon P: Ventricular asynchrony predicts a better outcome in patients with chronic heart failure receiving cardiac resynchronization therapy. J Am Coll Cardiol 2002, 40: 536-545. 10.1016/S0735-1097(02)02337-9View ArticleGoogle Scholar
- Marcus GM, Rose E, Viloria EM, Schafer J, De Marco T, Saxon LA, Foster E: VENTAK CHF/CONTAK-CD Biventricular Pacing Study Investigators. Septal to posterior wall motion delay fails to predict reverse remodeling or clinical improvement in patients undergoing cardiac resynchronization therapy. J Am Coll Cardiol 2005, 45: 2208-2216. 10.1016/j.jacc.2005.05.095View ArticleGoogle Scholar
- Sassone B, Capecchi A, Boggian G, Gabrieli L, Saccà S, Vandelli R, Petracci E, Mele D: Value of baseline left lateral wall postsystolic displacement assessed by m-mode to predict reverse remodeling by cardiac resynchronization therapy. Am J Cardiol 100(3):470-5. 2007, Aug 1; Epub 2007 Jun 15 10.1016/j.amjcard.2007.02.107Google Scholar
- Ansalone G, Giannantoni P, Ricci R, Trambaiolo P, Fedele F, Santini M: Doppler myocardial imaging to evacuate the effectiveness of pacing sites in patients receiving biventricular pacing. J Am Coll Cardiol 2002, 39: 489-499. 10.1016/S0735-1097(01)01772-7View ArticlePubMedGoogle Scholar
- Bader H, Garrigue S, Lafitte S, Reuter S, Jaïs P, Haïssaguerre M, Bonnet J, Clementy J, Roudaut R: Intra-left ventricular electromechanical asynchrony: a new independent predictor of severe cardiac events in heart failure patients. J Am Col Cardiol 2004, 43: 248-256. 10.1016/j.jacc.2003.08.038View ArticleGoogle Scholar
- Yu CM, Chau E, Sanderson JE, Fan K, Tang MO, Fung WH, Lin H, Kong SL, Lam YM, Hill MR, Lau CP: Tissue Doppler echocardiographic evidence of reverse remodeling and improved synchronicity by simultaneously delaying regional contraction after biventricular pacing therapy in heart failure. Circulation 2002, 105: 438-445. 10.1161/hc0402.102623View ArticlePubMedGoogle Scholar
- Innelli P, Sidiropulos M, Galderisi M: Color Tissue Doppler to appropriately select a candidate for resynchronization therapy and test the procedure efficacy. Echocardiography 2006, 23: 709-712. 10.1111/j.1540-8175.2006.00294.xView ArticlePubMedGoogle Scholar
- Ghio S, Constantin C, Klersy C, Serio A, Fontana A, Campana C, Tavazzi L: Interventricular and intraventricular dyssynchrony are common in heart failure patients, regardless of QRS duration. Eur Heart J 2004, 25: 571-578. 10.1016/j.ehj.2003.09.030View ArticlePubMedGoogle Scholar
- Yu CM, Fung WH, Zhang Q, Sanderson JE, Lau CP: Predictors of left ventricular remodeling after cardiac resynchronization therapy for heart failure secondary to idiopathic or dilated cardiomyopathy. Am J Cardiol 2003, 91: 684-688. 10.1016/S0002-9149(02)03404-5View ArticlePubMedGoogle Scholar
- Yu CM, Shang Q, Fung JWH, Chan HC, Chan YS, Yip GW, Kong SL, Lin H, Zhang Y, Sanderson JE: A novel tool to assess systolic asynchrony and identify responders of cardiac resynchronization therapy by tissue synchronization imaging. J Am Coll Cardiol 2005, 45: 677-684. 10.1016/j.jacc.2004.12.003View ArticlePubMedGoogle Scholar
- Sogaard P, Egeblad H, Kim WY, Jensen HK, Pedersen AK, Kristensen BØ, Mortensen PT: Tissue Doppler imaging predicts improved systolic performance and reversed left ventricular remodeling during long-term cardiac resynchronization therapy. J Am Coll Cardiol 2002, 40: 723-730. 10.1016/S0735-1097(02)02010-7View ArticlePubMedGoogle Scholar
- Mele D, Pasanisi G, Capasso F, De Simone A, Morales MA, Poggio D, Capucci A, Tabacchi G, Sallusti L, Ferrari R: Left ventricular myocardial deformation dyssynchrony identifies responders to cardiac resynchronization therapy in patients with heart failure. Eur Heart J 2006, 27: 1070-1078. 10.1093/eurheartj/ehi814View ArticlePubMedGoogle Scholar
- Porciani MC, Lilli A, Macione R, Cappelli F, Demarchi G, Pappone A, Ricciardi G, Padeletti L: Utility of a new left ventricular asynchrony index as a predictor of reverse remodeling after cardiac resynchronization therapy. Eur Heart J 2006, 27: 1818-1823. 10.1093/eurheartj/ehl133View ArticlePubMedGoogle Scholar
- Yu CM, Fung JW, Zhang Q, Chan CK, Chan YS, Lin H, Kum LC, Kong SL, Zhang Y, Sanderson JE: Tissue Doppler imaging is superior to strain rate imaging and postsystolic shortening on the prediction of reverse remodeling in both ischemic and nonischemic heart failure after cardiac resynchronization therapy. Circulation 2004, 110: 66-73. 10.1161/01.CIR.0000133276.45198.A5View ArticlePubMedGoogle Scholar
- Marwick T: Measurement of strain and strain rate by echocardiography: ready for prime time? J Am Coll Cardiol 2006, 47: 1313-1327. 10.1016/j.jacc.2005.11.063View ArticlePubMedGoogle Scholar
- Galderisi M: Can technical limitations of strain rate imaging be overtaken by particular arrangements. J Am Coll Cardiol 2006, 48: 1729. 10.1016/j.jacc.2006.07.020View ArticlePubMedGoogle Scholar
- Suffoletto MS, Dohi K, Cannesson M, Saba S, Gorcsan J: Novel speckle-tracking radial strain from routine black-and-white echocardiographic images to quantify dyssynchrony and predict response to cardiac resynchronization therapy. Circulation 2006, 113: 960-968. 10.1161/CIRCULATIONAHA.105.571455View ArticlePubMedGoogle Scholar
- Kapetanakis S, Kearney MT, Siva A, Gall N, Cooklin M, Monaghan MJ: Real-time three-dimensional echocardiography: a novel technique to quantify global left ventricular mechanical dyssynchrony. Circulation 2005, 112: 992-1000. 10.1161/CIRCULATIONAHA.104.474445View ArticlePubMedGoogle Scholar
- Burgess MI, Jenkins C, Chan J, Marwick TH: Measurement of left ventricular dyssynchrony in patients with ischaemic cardiomyopathy: a comparison of real-time three-dimensional echocardiography and tissue Doppler echocardiography. Heart, in press. 2007 Mar 7Google Scholar
- Badano LP, Baldassi M, Tosoratti E, Zakja E, Pavoni D, Dall'Armellina E, Gianfagna P, Fioretti PM: 3D echocardiography reduces the time needed to assess left ventricular synchronicity in heart failure patients with clinical indication to cardiac resynchronization therapy. (abs) Eur Heart J 2006, 27: 822.Google Scholar
- Badano LP, Baldassi M, Tosoratti E, Zakja E, Pavoni D, Dall'Armellina E, Gianfagna P, Fioretti PM: Accuracy of 3D echocardiography in assessing left intra-ventricular synchronicity using tissue synchronization imaging. (abs) Eur Heart J 2006, 27: 859.Google Scholar
- Van de Veire N, Bleeker GB, Ypenburg C, De Sutter J, Marsan NA, Holman ER, van der Wall EE, Schalij MI, Bax JJ: Usefulness of triplane Tissue Doppler Imaging to predict Acute Response to cardiac resynchronization therapy. Am J Cardiol 2007, 100: 476-482. 10.1016/j.amjcard.2007.03.051View ArticlePubMedGoogle Scholar
- Hunt SA, Abraham WT, Chin MH, Feldman AM, Francis GS, Ganiats TG, Jessup M, Konstam MA, Mancini DM, Michl K, Oates JA, Rahko PS, Silver MA, Stevenson LW, Yancy CW, Antman EM, Smith SC Jr, Adams CD, Anderson JL, Faxon DP, Fuster V, Halperin JL, Hiratzka LF, Jacobs AK, Nishimura R, Ornato JP, Page RL, Riegel B, American College of Cardiology American Heart Association Task Force on Practice Guidelines American College of Chest Physicians; International Society for Heart and Lung Transplantation; Heart Rhythm Society. ACC/AHA: Guideline Update for the Diagnosis and Management of Chronic Heart Failure in the Adult: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Update the 2001 Guidelines for the Evaluation and Management of Heart Failure): developed in collaboration with the American College of Chest Physicians and the International Society for Heart and Lung Transplantation: endorsed by the Heart Rhythm Society. Circulation 2005, 112: e154-235. Epub 2005 Sep 13 10.1161/CIRCULATIONAHA.105.167586View ArticlePubMedGoogle Scholar
- Swedberg K, Cleland J, Dargie H, Drexler H, Follath F, Komajda M, Tavazzi L, Smiseth OA, Gavazzi A, Haverich A, Hoes A, Jaarsma T, Korewicki J, Lévy S, Linde C, Lopez-Sendon JL, Nieminen MS, Piérard L, Remme WJ, Task Froce for the Diagnosis and Treatment of Chronic Heart Failure of the European Society of Cardiology: Guidelines for the diagnosis and treatment of chronic heart failure: executive summary (update 2005): The Task Force for the Diagnosis and Treatment of Chronic Heart Failure of the European Society of Cardiology. Eur Heart J 2005, 26: 1115-1140. Epub 2005 May 18 10.1093/eurheartj/ehi166View ArticlePubMedGoogle Scholar
- Adams KF, Lindenfeld J, Arnold JMO, Baker DW, Barnard DH, Baughman KL, Bohemer JP, Deedwania P, Dunbar SB, Elkayam U, Gheorgiade M, Howlett JK, Konstam MA, Kronenberg MW, Massie BM, Mehra MR, Miller AB, Moser OK, Patterson JH, Rodeheffer RJ, Sackner-Bersnstein J, Silver MA, Starling RC, Stevenson LW, Wagoner LE: Executive Summary : HFSA 2006 Comprehensive Heart Failure Practice Guideline. J Cardiac Failure 2006, 12: 10-38. 10.1016/j.cardfail.2005.12.001View ArticleGoogle Scholar
- Arnold JM, Liu P, Demers C, Dorian P, Giannetti N, Haddad H, Heckman GA, Howlett JG, Ignaszewski A, Johnstone DE, Jong P, McKelvie RS, Moe GW, Parker JD, Rao V, Ross HJ, Sequeira EJ, Svendsen AM, Teo K, Tsuyuki RT, White M: Canadian Cardiovascular Society. Canadian Cardiovascular Society consensus conference recommendations on heart failure 2006: diagnosis and management. Can J Cardiol 2006, 22: 23-45.View ArticlePubMedPubMed CentralGoogle Scholar
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.