Cardiac dyssynchrony ppt by dr awadhesh


Published on

Published in: Health & Medicine
  • Be the first to comment

Cardiac dyssynchrony ppt by dr awadhesh

  2. 2. INTRODUCTION  Cardiac resynchronization therapy (CRT) using atrio biventricular pacing has evolved into a useful therapeutic option for patients with heart failure, refractory to optimal medical therapy.  Improvements in quality of life, morbidity, mortality, severity of mitral regurgitation (MR) and left ventricular (LV) function have been demonstrated in large randomized clinical trials but the treatment is invasive and expensive. 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.
  3. 3. INTRODUCTION CONTD……  Besides, about one third of patients remain unresponsive in spite of the device implantation using the existing criteria.  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). 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.
  4. 4. INTRODUCTION CONTD…..  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) plays a important role.  There is thus a need to carefully identify the patients most likely to benefit by this intervention using indices of mechanical dyssynchrony. J Am Coll Cardiol 2002,40:1703-1719.
  5. 5. DEFINITIONS OF DYSSYNCHRONY  Electrical Vs Mechanical Dyssynchrony Electrical Dyssynchrony refers to a prolonged conduction time in the ventricles resulting in a prolonged QRS duration. Mechanical Dyssynchrony is the mechanical discoordination , usually associated with simultaneous contraction and stretch in different regions of the LV as well as delays in the time to peak contraction from one segment to another.
  6. 6. DELETERIOUS HEMODYNAMIC EFFECTS OF LV DYSSYNCHRONY Diminished SV & CO due:  Reduced diastolic filling time  Weakened contractility  Protracted MV regurgitation  Post systolic regional contraction Atrio- ventricular Inter-V Intra-V Cazeau, et al. PACE 2003; 26[Pt. II]: 137–143
  7. 7. TOOLS FOR DYSSYNCHRONY ASSESSMENT  2D Echocardiography  3D Echocardiography  MRI
  9. 9. ATRIOVENTRICULAR DYSSYNCHRONY  AV dyssynchrony reduces the duration of ventricular filling, thus inducing the appearance of diastolic mitral and tricuspid regurgitation and reducing stroke volume.  Atrio-ventricular (AV) dyssynchrony occurs in patients with dilated cardiomyopathy and first degree AV block and was the first objective of CRT by bicameral pacemakers in the early 1990s.
  10. 10. ATRIOVENTRICULAR DYSSYNCHRONY CONTD…… Atrioventricular dyssynchrony- is said to be present when diastolic filling period (DFP) occupies less than 40% of cardiac cycle (measured by R-R interval. 1. To obtain DFP, obtain the apical four-chamber view with mitral valve in the centre of the frame. 2. Using pulsed Doppler with the sample volume placed at the tips of mitral leaflets; obtain a spectral display of mitral inflow pattern. 3. Measure the time from the onset to the end of the spectral display- this represents DFP. 4. Measure the R-R interval using any two consecutive regular beats. Divide DFP with R-R interval and multiply by hundred to obtain a percentage value .
  11. 11. Assessment of atrioventricular dyssynchrony using pulsed-Doppler measurement of mitral inflow velocity at mitral leaflet tips
  12. 12. INTERVENTRICULAR DYSSYNCHRONY  Inter-ventricular dyssynchrony represents the discordance between the times of right ventricular (RV) and LV contraction.  Interventricular mechanical dyssynchrony is assessed by measuring the interventricular mechanical delay. 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.
  13. 13. INTERVENTRICULAR DYSSYNCHRONY CONTD…..  PW or CW Doppler images of aortic and pulmonary flow velocities are currently used to measure the inter-ventricular mechanical delay (IVMD).  A difference of IVMD values of > 40 ms and values of LV PEP of >140 ms are considered pathological . Echocardiographic modeling of cardiac dyssynchrony before and during multisite stimulation: a prospective study. Pacing Clin Electrophysiol 2003, 26:137-143.
  14. 14. INTERVENTRICULAR DYSSYNCHRONY  To obtain time to onset of LV ejection, obtain the apical five-chamber view and place the pulsed- Doppler sample volume at the left ventricular outflow tract (LVOT).  Measure the time from the onset of QRS complex to the onset of the pulsed-Doppler flow velocity. This is the LV pre-ejection period (LVPEP). Cardiac resynchronization therapy and the emerging role of echocardiography (Part 2); the comprehensive examination. J Am Soc 2007, 20:76-90.
  15. 15. INTERVENTRICULAR DYSSYNCHRONY  To obtain the time to onset of RV ejection, obtain the Right ventricular outflow tract (RVOT) view (para-sternal short axis) and place the pulsed Doppler sample volume at RVOT.  Measure the time interval from onset of QRS complex to the onset of pulse-Doppler velocity curve. This is the RV pre ejection period (RVPEP).  The difference of LVPEP and RVPEP gives interventricular mechanical delay .
  16. 16. LIMITATIONS  Presence of pulmonary arterial hypertension and/or RV systolic dysfunction, which can prolong RV PEP.  Concomitantly impaired increase of LV pressure in very severe CHF.
  17. 17. INTERVENTRICULAR DYSSYNCHRONY CONTD…..  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) . Echocardiographic evaluation of cardiac resynchronization therapy: ready for routine clinical use? A critical appraisal. J Am Coll Cardiol 2004, 44:1-9.
  18. 18. INTRAVENTRICULAR DYSSYNCHRONY  Intraventricular dyssynchrony is the principal factor responsible for contractile dysfunction, the one most affected by and most predictive of response to resynchronization therapy.  Large number of indices have been described and evaluated in studies using several echocardiographic modalities. Cardiac resynchronization therapy tailored by echocardiographic evaluation of ventricular asynchrony. J Am Coll Cardiol 2002, 40:1616-1622.
  19. 19. ASSESSMENT OF INTRAVENTRICULAR DYSSYNCHRONY 1. M-mode measurement of septal-posterior wall motion delay (SPWMD) 2. TDI for measurement of time to peak systolic longitudinal velocity of various myocardial segments & time to peak systolic longitudinal strain and strain rate of various myocardial segments 3. Assessment of radial dyssynchrony using speckle-tracking 4. Three-dimensional echocardiography Ventricular asynchrony predicts a better outcome in patients with chronic heart failure receiving cardiac resynchronization therapy. J Am Coll Cardiol 2002, 40:536-545.
  20. 20. M-MODE MEASUREMENT OF SPWMD This is the simplest technique to assess the septal to posterior wall motion delay. 1. Position the M-Mode cursor at the papillary muscle level in either the parasternal long or short axis view. 2. Keeping the sweep speed from 50-100 mm/second, measure the time delay from peak inward septal motion to peak inward posterior wall motion. Cardiac resynchronization therapy and the emerging role of echocardiography; the comprehensive examination. J Am Soc 2007, 20:76-90.
  21. 21. M-MODE MEASUREMENT OF SPWMD ……….  In the original experience of Pitzalis et al on 20 patients with advanced heart failure, a SPWMD (determined in parasternal short-axis view) of >130 ms was considered pathological and SPWMD predicted inverse LV remodeling and long-term clinical improvement after CRT, with 100% sensitivity, 63% specificity and 85% accuracy . Cardiac resynchronization therapy tailored by echocardiographic evaluation of ventricular asynchrony. J Am Coll Cardiol 2002, 40:1616-1622.
  22. 22. ADVANTAGE & LIMITATION OF SPWMD  The main advantages of this method correspond to the low- cost technique and the availability in all the echocardiographic machines.  The limitations include the impossibility to measure SPWMD in patients with a poor acoustic window, previous septal or posterior wall myocardial infarction, or abnormal septal motion secondary to RV pressure or volume overload.  In addition, M-mode can only visualize dyssynchrony of the anterior septum or posterior wall whereas other LV walls can be involved.
  23. 23. COLOR TDI IMAGING, M-MODE M-MODE MEASUREMENT OF SPWMD is quite simple and widely available but it is often quite difficult to identify the peaks in both the walls. To overcome this shortcoming, color TDI M-mode is now recommended as it enables the identification of the peak systole by the sharp color transition 1. Position the M-Mode cursor at the papillary muscle level in either the parasternal long or short axis view. 2. Keeping the sweep speed from 50-100 mm/second, select color TDI. 3. Measure the time delay from peak inward septal motion to peak inward posterior wall motion, as indicated by the sharp color transition . A value > 130ms signifies dyssynchrony and response to CRT with a high degree of sensitivity.
  24. 24. LATERAL WALL POST-SYSTOLIC DISPLACEMENT (LWPSD)  A another method, reported by Sassone et al, determines lateral wall post-systolic displacement (LWPSD), measured as the difference of intervals from QRS onset to maximal systolic displacement of the basal LV lateral wall (assessed by M-mode in the apical 4-chamber view) and from QRS onset to the beginning of transmitral E velocity (assessed by pulsed Doppler of mitral inflow).  A positive LWPSD i.e. a longer interval to maximal inward displacement of LV lateral wall than the interval to opening of the mitral valve, identifies a severe post-systolic contraction and has been demonstrated to be an independent predictor of CRT response in 48 patients with end-stage heart failure and left bundle branch block. 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  QRS onset to maximal systolic displacement of the basal LV lateral wall (assessed by M- mode in the apical 4- chamber view) QRS onset to the beginning of transmitral E velocity (assessed by pulsed Doppler of mitral inflow) Minus
  25. 25. Methodology for measuring lateral wall post-systolic displacement (LWPSD). It is measured as the difference of the time interval from QRS onset to maximal systolic displacement of the basal LV lateral wall (assessed by M-mode in the apical 4- chamber view) (upper panel) and the time interval from QRS onset to the beginning of transmitral E velocity (assessed by pulsed Doppler of mitral inflow) (lower panel). In this example, the positive value of the difference indicates the co-existence of segmental post-systolic contraction and diastolic relaxation. (Modified from Sassone B et al, Am J Cardiol 2007;100:470–475).
  26. 26. LATERAL WALL POST-SYSTOLIC DISPLACEMENT (LWPSD)……….  Of interest, despite evaluating intra-ventricular dyssynchrony based on delay of a single myocardial wall, LWPSD could predict CRT response.  This may rely to the fact that, in the presence of left bundle branch block, the lateral wall is the latest to be activated, theoretically representing the optimal target for LV lead positioning.  This method has not yet tested in patients without left bundle branch block and its diagnostic accuracy is unknown.  In addition. it needs the identical heart rate when measuring the M-mode and pulse Doppler imaging.
  27. 27. TDI FOR ASSESSMENT OF INTRAVENTRICULAR DYSSYNCHRONY  Measurement of time to peak- systolic longitudinal velocity-  Assessment of longitudinal shortening velocities ie the time of myocardial systolic velocities (Sm) from the apical window with TDI has been studied extensively and several indices proposed.  There are two approaches possible- pulsed-TDI or color-coded TDI but owing to several limitations with pulsed-TDI, color TDI is now the preferred method. Doppler myocardial imaging to evacuate the effectiveness of pacing sites in patients receiving biventricular pacing. J Am Coll Cardiol 2002, 39:489-499.
  28. 28. MEASUREMENT OF TIME TO PEAK- SYSTOLIC LONGITUDINAL VELOCITY- 1. Obtain a noise free ECG trace and good quality 2D image from the apical window with the LV cavity in the centre of image sector and the depth adjusted to include the mitral annulus. 2. Activate color TDI, adjusting the sector width so as to keep the frame rate > 90 frames/second. 3. Suspend breathing if possible and acquire 3-5 beats (sinus rhythm) or more (in case of ectopics). 4. 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.
  29. 29. Methodology for measuring pulsed Tissue Doppler derived time to peak Sm and time to onset Sm (left panel). In the right panel measurements of time to peak Sm (upper panel) and of time to onset Sm (lower panel) are depicted. Am=Myocardial atrial velocity, CTm = Contraction time, Em = Myocardial early diastolic velocity, RTm = Myocardial relaxation time, Sm = Myocardial systolic velocity. Mod from Agler DA et al, J Am Soc Echocardiogr 2007;20:76–90.
  30. 30. TIME TO PEAK- SYSTOLIC LONGITUDINAL VELOCITY  The most widely used measurements correspond to the time interval between the onset of ECG derived QRS and the Sm peak (= time to Sm peak) and the time interval between the onset of QRS and the onset of Sm (= time to Sm onset), which correspond to LV PEP.  Intra-ventricular mechanical delay has been defined for differences of > 65 ms of time to Sm peak between LV segments. 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.
  31. 31. TIME TO PEAK- SYSTOLIC LONGITUDINAL VELOCITY CONTD……  Receiver-operator characteristic curve analysis demonstrated that this cut-off value yielded a sensitivity and specificity of 80% to predict clinical improvement and of 92% to predict LV reverse remodeling in 85 patients with end-stage heart failure, QRS duration > 120 ms, and left bundle-branch block. 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.
  32. 32. LIMITATION OF PW TISSUE DOPPLER  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.
  33. 33. COLOUR TISSUE DOPPLER 1. Off-line colour Tissue Doppler derived Tissue Velocity Imaging (TVI), 2. SRI
  34. 34. COLOUR TISSUE DOPPLER  Off-line colour Tissue Doppler derived Tissue Velocity Imaging (TVI), Tissue Synchronization Imaging (TSI) and SRI can be used to assess intra-ventricular dyssynchrony in the longitudinal plane (apical views).  The common advantages of these techniques is the possibility of measuring the dyssynchrony of opposite LV walls (= horizontal dyssynchrony) and of different segments of the same LV wall (= vertical dyssynchrony) in a given view, from the same cardiac cycle.
  35. 35. Methodology for recording and measuring intra-ventricular horizontal and vertical dyssynchrony by off-line color Tissue Doppler techniques. Horizontal dyssynchrony occurs between opposite walls. Vertical dyssynchrony is between different segments of the same wall.
  36. 36. COLOUR TISSUE DOPPLER  TVI measures the time to Sm peak (Ts) or the time to Sm onset in LV basal and middle segments of the three standard apical views.  By identifying the presence of one or more differences > 50 ms among regional times of Sm onset, suggests significant intraventricular dysynchrony .  Ghio and coworkers have demonstrated that intraventricular dyssynchrony is detectable even in 29.5 % of patients with advanced LV dysfunction but normal QRS duration by this criteria. Echocardiography 2006, 23:709-712. Sample of time to peak (Ts) measured by off-line color TVI pre and post CRT at the level of anterior septum and postero-lateral wall, in apical 5-chamber view. Aortic valve opening (AVO) and closure (AVC) are derived by previous placement of markers on the onset and the end of LV Doppler outflow. Pre-CRT Ts of postero-lateral wall (upper panel) is clearly delayed in comparison to Ts of anterior septum. Post-CRT the time duration of Ts between the two walls is clearly shortened (lower panel). (Modified from Innelli P et al, Echocardiography 2006;23:709– 716)
  37. 37. COLOUR TISSUE DOPPLER CONTD…. o Using a LV 12-segment model. A dyssynchrony index (DI) or Yu index can be derived as the Standard deviation of the average values of Ts ie (Ts-SD). o As per Yu et al Ts-SD of > 32.6 ms predicts inverse LV remodeling after CRT with 100% sensitivity, 100% specificity and 100% accuracy in 30 candidates to CRT. 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.
  38. 38. DYSSYNCHRONY INDEX (DI)  Methodology of calculation of Dyssynchrony Index and is ability in predicting LV inverse remodeling.  In the upper panel methodology of calculation of Dyssynchrony Index, i.e., the standard deviation of Ts (Ts-SD) measured in the basal and mid- segments visualizable in the apical views.  In the lower panel, Ts-SD shows the ability to predict an effective LV inverse remodeling after CRT (lower panel). Values of TS-SD > 32.6 (black triangles) predict an effective LV reverse remodeling (DLVVs = delta left ventricular end-systolic volumes) after CRT. Patients with pre-CRT values of Ts-SD < 32.6 (empty circles) do not present significant LV inverse remodeling at follow-up. (Modified from Yu CM et al, Am J Cardiol 2003;91:684–688)
  39. 39. TISSUE SYNCHRONIZATION IMAGING (TSI)  TSI is an implementation of Ts method.  It displays Ts (time to Sm peak) 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). 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.
  40. 40. Four-dimensional tissue synchronization imaging (TSI) of a normal individual. From the different views (left), a three-dimensional impression of the left ventricle is reconstructed (middle). The entire three-dimensional image of the left ventricle is green indicating no dyssynchrony. Post- processing allows the display of the different segments in a polar map format (right) to further facilitate identification of the site of latest activation.
  41. 41. Four-dimensional tissue synchronization imaging (TSI) of a patient with left ventricular dyssynchrony. From the different views (left), a three-dimensional impression of the left ventricle is reconstructed (middle). The region of latest activation is indicated in red. Post- processing yields the polar-map format (upper right) indicating in red the site of latest activation (anteroseptal), and further calculations can be performed (lower right) to further quantify the extent of left ventricular dyssynchrony using different parameters.
  42. 42. SPECKLE TRACKING  This is a 2-D strain technique and has 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.
  43. 43. STRAIN  The principal benefit of LV shear strains is amplification of the 15% shortening of myocytes into 40% radial LV wall thickening, which ultimately translates into a >60% change in LV ejection fraction.  Left ventricular shearing increases towards the subendoardium, resulting in a subepicardial to subendocardial thickening strain gradient.
  44. 44. STRAIN……  Dyssynchrony from timing of peak radial strain has been demonstrated to be correlated with Tissue Doppler measures.  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. Circulation 2006, 113:960-968.
  45. 45. STRAIN…….  Another possibility, proposed by Porciani et al, considers the time spent by 12 LV segments in contracting after AVC, i.e., during the isovolumic relaxation time, and measures the sum of the time of strain tracing exceeding AVC (ExcT) on the 12 LV basal and mid-segments (cut-off value = 760 ms, 93.5% sensitivity and 82.8% specificity). Eur Heart J 2006, 27:1818-1823.
  46. 46. Methodology for measuring time of exceeding aortic valve closure contraction. The sum of the time of strain tracing exceeding aortic valve closure (ExcT) is calculated on the 12 LV basal and middle segments in the standard apical views. AVO = aortic valve opening, AVC = aortic valve closure(Modified from Porciani MT et al, Eur Heart J 2006;27:1818–1823)
  47. 47. DYSSYNCHRONY ASSESSMENT The data thus obtained can be used to calculate any of the several proposed dyssynchrony indices, as below –  Delay in time-to-peak-systolic velocity between opposing walls- > 65msec.  Maximum delay in time-to-peak-systolic velocity between any two myocardial segments- >100msec.  Standard deviation of the time-to-peak-systolic velocity of the 12 basal and mid LV segments- > 33msec. J Am Coll Cardiol Img 2010;3:132– 40
  48. 48. THREE-DIMENSIONAL ECHOCARDIOGRAPHY FOR ASSESSMENT OF DYSSYNCHRONY  Real time 3D echocardiography (RT3DE) is a relatively new but very promising tool in the assessment of dyssynchrony.  The greatest advantage of RT3DE is that it enables the comparison of synchrony in all segments in the same cardiac cycle.  Quantitative analysis involves using software which enables LV volumetric analysis with semiautomatic edge detection to produce a cast of the LV cavity. Eur Heart J 2006, 27:859.
  49. 49. THREE-DIMENSIONAL ECHOCARDIOGRAPHY FOR ASSESSMENT OF DYSSYNCHRONY……. o The global LV volumetric dataset has been used to determine a dyssynchrony index that corresponds to the standard deviation of the average of the time intervals needed by multiple LV segments to reach minimal end-systolic volume. o This index is expressed as the percent value of the overall cardiac cycle, in order to be able to compare patients with different heart rates. o CRT responders show a significant reduction of this 3-D dyssynchrony index, which parallels the reduction of LV enddiastolic volume and the increase in EF 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.
  50. 50. LIMITATIONS OF 3-D ECHOCARDIOGRAPHY  The limitations of 3-D method are its suboptimal feasibility (<80%), its temporal resolution of about 40–50 ms, and its inability to distinguish active from passive motion or to make analysis in the presence of atrial fibrillation and/or recurrent premature beats.
  51. 51. 3-D derived time-volume curves of 16-segment model. Presentation 3-D derived time-volume curves of 16-segment LV model in a patient with intra-ventricular dyssynchrony. Each LV myocardial segment is codified by a different colours.
  53. 53. MRI FOR DYSSYNCHRONY  VENC-MRI and cine-MRI were performed in 20 patients with heart failure NYHA class III and reduced ejection fraction before CRT device implantation.  The interventricular mechanical delay (IVMD) was assessed by VENC-MRI as the temporal difference between the onset of aortic and pulmonary flow.  Intraventricular dyssynchrony was quantified by cine-MRI, using the standard deviation of time to maximal wall thickening in sixteen left ventricular segments.  RESULTS  14 patients (70 %) clinically responded to CRT. A similar accuracy was found to predict the response to CRT by measurements of the IVMD.  ALSO data analysis of the IVMD is significantly less time-consuming. Quantification of mechanical ventricular dyssynchrony: direct comparison of velocity-encoded and cine magnetic resonance imaging. Ref. JACC 2011 Jun;183(6):554-60. Epub 2011 Apr 12.
  54. 54. LV DYSSYNCHRONY AS ASSESSED WITH PHASE ANALYSIS FROM GATED MYOCARDIAL PERFUSION SPECT (GMPS) Journal of the American College of Cardiology, Vol. 49, No. 16, 2007
  55. 55. Example of a patient without left ventricular (LV) dyssynchrony on gated myocardial perfusion single-photon emission computed tomography (GMPS). The non- normalized (upper panel) and normalized (lower panel) phase distributions are nearly uniform, and the corresponding phase histograms are highly peaked, narrow distributions.
  56. 56. Example of a patient with LV dyssynchrony derived from GMPS. The non-normalized (upper panel) and normalized (lower panel) phase distributions show significant non- uniformity and the corresponding phase histograms are widely spread distributions.
  57. 57. LIMITATIONS OF GATED MYOCARDIAL PERFUSION SPECT (GMPS)  Several limitations need to be acknowledged.  First, follow-up data after CRT implantation were not available; therefore, it remains to be determined what the value of GMPS is for prediction of response to CRT.  Another limitation of GMPS, in general, is that GMPS is less suitable than echocardiography for follow-up after CRT implantation, due to the radiation burden.
  61. 61. DYSSYNCHRONY IN THE NARROW QRS PATIENT POPULATION  If CRT can be shown to be of benefit to these patients(narrow QRS), the application of echocardiographic assessment of dyssynchrony is potentially of great importance for patient selection for therapy.  Trials showing benefit of CRT-  Bleeker et al showed CRT to benefit in 33 patients with NYHA class III/VI heart failure and EF less than or equal to 35%, but QRS less than 120 milliseconds, who had mechanical dyssynchrony defined as a septal-to-lateral wall time-to-peak systolic velocity delay of greater than or equal to 65 milliseconds by TD.(J Am Coll Cardiol 2006;48:2243-50.)
  62. 62. DYSSYNCHRONY IN THE NARROW QRS PATIENT POPULATION……….  Yu et al reported results on 51 patients with heart failure with narrow QRS (120 milliseconds) who had CRT based on TD measures of dyssynchrony. CRT resulted in significant reductions of LV end-systolic volume, and improvement of NYHA class, 6- minute hall-walk distance, and EF, similar to patients with wide QRS who underwent CRT.(J Am Coll Cardiol 2006;48:2251-7)  The first randomized trial of CRT in patients with heart failure with narrow QRS complexes (130 milliseconds), known as the RethinQ trial, was published by Beshai et al .This trial failed to show a therapeutic effect of CRT on the primary end point of peak myocardial oxygen consumption. Although a positive effect of CRT was observed on the secondary end point of improvement in NYHA functional class, other parameters including quality-of-life score, 6-minute walk test, and LV reverse remodeling did not change. (N Engl J Med 2007;357:2461-71.)
  63. 63. CONCLUSIONS In patients with systolic heart failure and a QRS duration of less than 130 msec, CRT does not reduce the rate of death or hospitalization for heart failure and may increase mortality. (0ct 2013)
  64. 64.  According to ASE the dyssynchrony reporting in cases with borderline ECG should not include a recommendation whether a patient should undergo CRT or not, as this should be a clinical decision on a case-by-case basis.
  65. 65. POST CRT AV DELAY OPTIMIZATION  Because the ventricles are paced in CRT, the AV delay needs to be programmed.  The optimal programmed AV delay for an electronic pacemaker has been defined as the AV delay that allows completion of the atrial contribution to diastolic filling resulting in most favorable preload before ventricular contraction.
  66. 66. AV DELAY OPTIMIZATION  An AV delay programmed too short will result in absence or interruption of the atrial component (mitral A wave) by the premature ventricular contraction and closure of the mitral valve.  An AV delay programmed too long can result in suboptimal LV preload or diastolic MR, or may even allow native LV conduction, which defeats the purpose of CRT.  A simplified Doppler screening protocol after CRT implantation is proposed using pulsed Doppler mitral inflow, because no consensus currently exists for the routine performance of AV optimization after CRT.
  67. 67. AV DELAY OPTIMIZATION………  Auricchio et al concluded that although AV delay often positively impacts hemodynamics, LV resynchronization of intraventricular dyssynchrony is more important.(Circulation 1999;99:2993-3001)  A larger report of 215 patients undergoing Doppler guided AV optimization found small differences between the baseline and post-AV optimization average AV delay (120 vs 135 milliseconds, respectively).  Furthermore, AV optimization enhanced LV hemodynamics in only a minority of patients with CRT, suggesting that a significant percentage of patients do not need to undergo formal AV optimization.  Patients with intra-atrial conduction delay at baseline appeared to benefit greatest by prolonging the AV delays (150-250 milliseconds) during AV optimization. Kedia N, Ng K, Apperson-Hansen C, et al. Usefulness of atrioventricular delay optimization using Doppler assessment of mitral inflow in patients undergoing cardiac resynchronization therapy. Am J Cardiol 2006;98:780-5.
  68. 68. THE ITERATIVE METHOD OF AV DELAY OPTIMIZATION  It begins by programming the CRT device in atrial synchronous V pacing mode testing a series of AV intervals sequentially.  This usually begins with an AV delay of 200 milliseconds, then decreases in increments of 20-millisecond intervals to a minimum AV delay as short as 60 milliseconds.  The minimal AV delay that allows for adequate E and A wave separation and termination of the A wave at approximately 40 to 60 milliseconds before the onset of the QRS would be considered the optimal AV delay, and usually corresponds with a stage I diastolic filling pattern.
  69. 69. AV DELAY OPTIMIZATION……..  Technical features include positioning the pulsed wave sample volume deeper toward the left atrium (as opposed to the standard position at the mitral leaflet tips) to optimize detection of the mitral valve closure click, preparing settings of high sweep speeds and low filters, and inputting the ECG signal from the device directly to the ultrasound system, if possible.
  70. 70. AV DELAY OPTIMIZATION……….  A variation on the iterative method for AV optimization uses transaortic Doppler velocities as a surrogate for stroke volume.  The optimal sensed and paced AV delay is determined by the maximum aortic time-velocity integral value at 6 selected paced and sensed AV delays.  A typical protocol will include measurements at AV delays of 60, 80, 100, 120, 140, and 160 milliseconds, with each paced and sensed AV delay setting separated by a rest period of at least 10 to 15 beats.
  71. 71. CONCLUSION  Good quality ECG with a stable baseline and clear delineation of the onset of QRS complex is an essential requirement for accurate measurement of time periods.  Choose an ectopic free sequence and acquire at least 3-5 beats with breath held in expiration.  For TDI analysis, a sweep speed of 50-100 is recommended to improve temporal resolution.  Tissue Doppler analysis is highly angle dependent and misaligned images produce velocity curves consisting of not only the longitudinal but also the radial velocities. The sample volume should be as parallel as possible to the incident beam.
  72. 72. CONCLUSION  While analyzing color TDI data, the region-of-interest should be moved within the myocardial segment to obtain the most reproducible velocity curve with minimum artifacts.  If more than one systolic peak is obtained in the tissue velocity curve, the most reproducible peak of maximum amplitude should be used for analysis. If two or more peaks have same amplitude, the earlier peak should be taken into consideration.  For 3D imaging, optimum gain settings with clear delineation of the endocardial border, especially at the apex should be ensured.
  73. 73. CONCLUSION  A complete echocardiographic study along with quantitation of mitral regurgitation should always be performed in all cases.  Right ventricular systolic function should also be assessed routinely during dyssynchrony analysis and the findings should be reported.  No single parameter is predictive and there is no standard recommended approach. Hence, all the parameters possible depending on the laboratory and expertise should be evaluated.
  74. 74. CONCLUSION  The real value of these novel technologies remains to be determined in randomized trials  Several imaging techniques were evaluated (magnetic resonance imaging, speckle tracking echocardiography, strain imaging, nuclear imaging) and yielded several parameters of LV mechanical dyssynchrony that have demonstrated to be independent determinants of CRT response and long-term outcome in several observational studies.
  75. 75. Everything should be made as simple as possible, but not simpler. —Albert Einstein THANKS