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Influence of the atrio-ventricular delay optimization on the intra left ventricular delay in cardiac resynchronization therapy

Cardiovascular Ultrasound volume 4, Article number: 5 (2006) Cite this article

Abstract

Background

Cardiac Resynchronization Therapy (CRT) leads to a reduction of left-ventricular dyssynchrony and an acute and sustained hemodynamic improvement in patients with chronic heart failure. Furthermore, an optimized AV-delay leads to an improved myocardial performance in pacemaker patients. The focus of this study is to investigate the acute effect of an optimized AV-delay on parameters of dyssynchrony in CRT patients.

Method

11 chronic heart failure patients with CRT who were on stable medication were included in this study. The optimal AV-delay was defined according to the method of Ismer (mitral inflow and trans-oesophageal lead). Dyssynchrony was assessed echocardiographically at three different settings: AVDOPT; AVDOPT-50 ms and AVDOPT+50 ms. Echocardiographic assessment included 2D- and M-mode echo for the assessment of volumes and hemodynamic parameters (CI, SV) and LVEF and tissue Doppler echo (strain, strain rate, Tissue Synchronisation Imaging (TSI) and myocardial velocities in the basal segments)

Results

The AVDOPT in the VDD mode (atrially triggered) was 105.5 ± 38.1 ms and the AVDOPT in the DDD mode (atrially paced) was 186.9 ± 52.9 ms. Intra-individually, the highest LVEF was measured at AVDOPT. The LVEF at AVDOPT was significantly higher than in the AVDOPT-50setting (p = 0.03). However, none of the parameters of dyssynchrony changed significantly in the three settings.

Conclusion

An optimized AV delay in CRT patients acutely leads to an improved systolic left ventricular ejection fraction without improving dyssynchrony.

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Background

Asynchronous myocardial contraction in heart failure is associated with poor prognosis. Recent studies have shown an acute and sustained hemodynamic improvement after biventricular pacing (BVP), reversal of LV-remodelling, an increased quality of life, a reduction of symptoms of heart failure, and an improvement of exercise tolerance [1–7].

The optimization of the AV delay in DDD pacemaker patients is generally recommended and is performed in clinical practice. A variety of invasive and non-invasive methods were assessed in the past [8–15]. Recent studies have shown that also in CRT patients, invasively (dP/dt) [16–19] and non-invasively measured hemodynamic parameters (stroke volume) [20, 21] are modified according to the programmed AV delay. A hemodynamically optimal AV delay can be defined.

Ismer's method of AV delay optimization [22] is validated for biventricular as well as right ventricular DDD pacing.

Tissue Doppler Imaging (TDI) is an evaluated tool in clinical practice to identify myocardial dyssynchrony. TDI (including strain and strain rate) imaging measures regional wall motion velocities and can accurately quantify regional left ventricular function [24].

Strain measures compression and distension of myocardial segments ("deformation imaging") and strain rate imaging expresses strain changes per time interval [25]. TSI (Tissue Synchronization Imaging) utilizes color-coded time-to-peak tissue Doppler velocities and visualizes segments of dyssynchrony in real-time by superimposing these temporal motion data on 2D echo images. [26, 27].

These new techniques could potentially improve patient selection and guidance of implantation and programming of the devices for BVP. There is a variety of methods to determine dyssynchrony as summarized elsewhere [28].

There are no published data on the correlation of parameters of dyssynchrony and programming of the optimal AV interval. Aims of our study were therefore to investigate the influence of an optimized AV delay determined by the method of Ismer et al. [22] on dyssynchrony.

Methods

Patients

141 chronic heart failure patients of our clinic were included in this study. All patients had a biventricular ICD (pre-implantation NYHA III-IV, EF < 35%, QRS width > 120 ms). Clinical characteristics are demonstrated in Table 1. Patient exclusion criteria were as follows: atrial fibrillation, pacemaker malfunction and oesophageal diseases, NYHA IV, prosthetic mitral valve replacement.

Table 1 Patient characteristics
Full size table

AV delay: components and optimization

For the AV delay optimization we used the method proposed by Ismer et al [22].

This approach needs the placement of a bi-polar oesophageal electrode to provide a filtered left-atrial electrogram (LAE). We applied a 5F oesophagus electrode (Osypka TO2/5F, order no. TA12991101, Rheinfelden, Germany). Filtered oesophageal electrogram and telemetric real-time pacemaker markers provided by the programmer's analogue output were superimposed on the display of transmitral flow velocity on the Doppler-echo system (Figure 1). The simultaneous recording of transmitral flow, the left atrial oesophageal electrogram and the real-time sense-event markers, allow determining the components of the optimal AV delay (Table 2, Figure 1 and 2).

Figure 1
figure 1

Measurement of the IACT in the VDD - Mode = MA-LA. MA = right atrial sensing marker (see marker channel). LA = left atrial deflection (see oesophageal ECG). In this particular patient the IACT is 48 ms.

Full size image
Table 2 Measurement of the components of the optimal AV delay according to Ismer et al. [22]
Full size table
Figure 2
figure 2

Assessment of the left-atrial electromechanical action = LA-EAClong. LA = left atrial deflection (see oesophagus- ECG). EAClong = the end of the A-wave in an unphysiologically long AV-intervall. In this particular patient the LA-EAClang is 160 ms

Full size image

Based on these measurements, optimal AV delays were calculated for VDD (atrial-triggered) and DDD (atrial-paced) mode using the equations:

AVDOPT VDD = MA-LA + LA-EAClong - Sv-EACshort

and

AVDOPT DDD = SA-LA + LA-EAClong - Sv-EACshort

Echocardiograhy

Echocardiography to assess dyssynchrony was performed subsequently under three pacemaker settings: optimal AV delay (AVDOPT), optimal AV delay minus 50 ms (AVDOPT-50), optimal AV delay plus 50 ms (AVDOPT+50).

Echocardiography was performed on the Vivid 5 and Vivid 7 Dimension (GE Vingmed Ultrasound, Horton, Norway) machines. The TDI and strain analysis were performed in an off-line work station. The LVEF was assessed by area-length method in the apical four chamber view. The CI and the SV were calculated from the systolic velocities measured by PW-Doppler in the aortic outflow tract. Strain rate, tissue Doppler velocities were measured in the basal segments of the apical four-, three- and two-chamber views.

Statistics

Values are expressed as mean ± standard deviation (SD). Groups were compared by parametric or non-parametric tests (t-tests and Wilcoxon-Mann-Whitney tests, respectively). Statistical significance was assumed at a value of P < 0.05. Statistical analysis was performed with the SPSS 12 software package (SPSS; Chicago, Ill, USA).

Results

Optimal AV delay

In all patients, we could define an optimal AV delay in the VDD and the DDD modes respectively. The AVDOPT in VDD mode was 105.5 ± 38.1 ms and the AVDOPT in the DDD pacing mode was 186.9 ± 52.9 ms. The results are summarized in Table 3. As expected, the mean optimal AV delay was lower in the VDD than in the DDD mode.

Table 3 AVDOPT VDD = optimal AV delay for atrially triggered (VDD) and atrially paced (DDD) modes
Full size table

Echocardiography was performed subsequently under three pacemaker settings: AVDOPT, AVDOPT-50, AVDOPT+50. All patients had continuous biventricular stimulation even under AVDOPT+50.

2D and TDI echocardiography

The LVEF with AVDOPT was 28% (± 12%), with an AVDOPT-50 20% (± 7%, p= 0.03 compared to AVDOPT), with an AVDOPT+50 23% (± 7%, p = 0.11 compared to AVDOPT). The heart rate did not change significantly in the different settings (AVDOPT: 65,4/min, AVDOPT-50: 65,6/min, AVDOPT+50: 65,8 ms). The hemodynamics (SVI, CI, LVEF) and the TDI derived data are listed in Table 4. There was no significant difference of the amount of segments with dyssynchrony in TSI in the three settings. The maximal delay in the basal segments in the apical two-, three- and four-chamber views measured by TSI and strain did not differ in the AVDOPT, AVDOPT+50 and AVDOPT-50 setting.

Table 4 Hemodynamic and Tissue Doppler Echocardiography parameters in the AVDOPT, AVDOPT-50 and AVDOPT+50 modes.
Full size table

Discussion

Optimal AV delay

To date, Ismer's method for the optimal AV delay was applied to patients with DDD pacemakers and normal left ventricular function [22, 23]. This is the first study to assess the optimal AV delay by Ismer's method in patients with reduced left ventricular function. In our CRT patients, an optimal AV delay according to Ismer's method could be defined. This is the only method that allows separate measurement of the three AV-delay components: i.e., the pacemaker-related interatrial conduction time, the left-atrial electromechanical action, and the left-ventricular latency period. The benefits of this method, however, are offset by the necessity for placement of an oesophageal electrode. This requirement explains why only a few medical centres have applied this method in clinical practice and in most cases for purposes of scientific investigation only.

Our results concerning the AVDOPT in the VDD mode (105.5 ± 38.1 ms) are in agreement with the results of other studies on AVDOPT in CRT patients: Butter [16] determined an AVDOPT of 100 ms in 30 patients, Auricchio [17] an AVDOPT of 112 ± 33 ms in 41 patients and Kass [18] an AVDOPT of 125 ± 49 ms. A study that was recently published by Porciani [29] found an AVDOPT during simultaneous biventricular pacing of 97 + 27 ms.

In the literature, there are no published data on AVDOPT in DDD mode. Therefore, our AVDOPT in DDD mode of 186.9 ± 52.9 ms cannot be compared to other studies.

Hemodynamics

Intra-individually, the patients had the best LVEF under optimal AV-delay compared to the +50 and -50 ms settings. The LVEF is significantly higher in the AVDOPT setting than in the AVDOPT -50 setting. Obviously the formation of "cannon waves" seen with a shorter AV interval (AVDOPT -50) had a more negative hemodynamic effect than the diastolic mitral regurgitation seen with longer AV delays (AVDOPT +50). The hemodynamically unfavourable effects of "cannon waves" are described since the beginning of pacemaker therapy and are also termed "pacemaker syndrome". It is generally accepted that an adequate pacemaker programming can avoid this [30]. Toda et al. [31] could show in his studies that the mean LVEF in AVDOPT is higher than in prolonged AV delays. However, he found no significant difference.

Dyssynchrony

Changes of dyssynchrony can be seen immediately, as seen in studies that have examined on/off comparisons in CRT patients [32]. However, an optimized AV interval does not change the markers of dyssynchrony. The reason for the improved hemodynamic situation under AVDOPT seems to be the better left ventricular filling and not the altered dyssynchrony.

Limitations

This study included only a small number of patients. There was no follow-up examination of the patients.

Conclusion

This study confirmed that an optimized AV delay improves the left ventricular ejection fraction. Acutely, the optimized AV delay does not influence left ventricular dyssynchrony. Whether a long-term AVDOPT leads to changes in left ventricular dyssynchrony via an improved LVEF and reverse remodelling can only be speculated. This has to be addressed in future studies with a long-term observation interval.

Abbreviations

AVDOPT :

optimal AV delay

AVDOPT-50:

optimal AV delay -50 ms

AVDOPT+50:

optimal AV delay + 50 ms

CRT:

Cardiac Resynchronization Therapy

DCM:

Dilated Cardiomyopathy

EMD:

Electromechanical Delay

IVMD:

Inter-ventricular mechanical delay

LBBB:

Left Bundle Branch Block

SRI:

strain rate imaging

TDI:

Tissue Doppler Imaging

TSI:

Tissue Synchronization Imaging

VDD:

atrially triggered mode

DDD:

atrailly paced mode

EAC:

the end of the A-wave

LVEF:

Left ventricular ejection fraction

References

  1. Bristow MR, Saxon LA, Boehmer J, Krueger S, Kass DA, De Marco T, Carson P, DiCarlo L, DeMets D, White BG, DeVries DW, Feldman AM, Comparison of Medical Therapy Pacing and Defibrillation in Heart Failure (COMPANION) Investigators: Cardiac Resynchronization Therapy with or without an Implantable Defibrillator in Advanced Chronic Heart Failure. N Eng J Med 2004, 350: 2140-2150. 10.1056/NEJMoa032423

    Article  CAS  Google Scholar 

  2. Linde C, Leclercq C, Rex S, Garrigue S, Lavergne T, Cazeau S, McKenna W, Fitzgerald M, Deharo JC, Alonso C, Walker S, Braunschweig F, Bailleul C, Daubert JC: Long-term benefits of biventricular pacing in congestive heart failure: results from the MUltisite STimulation in cardiomyopathy (MUSTIC) study. J Am Coll Cardiol 2002, 40: 111-118. 10.1016/S0735-1097(02)01932-0

    Article  PubMed  Google Scholar 

  3. Abraham WT, Fisher WG, Smith AL, Delurgio DB, Leon AR, Loh E, Kocovic DZ, Packer M, Clavell AL, Hayes DL, Ellestad M, Trupp RJ, Underwood J, Pickering F, Truex C, cAtee P, Messenger J, MIRACLE Study Group: Multicenter InSync Randomized Clinical evaluation. Cardiac resynchronization in chronic heart failure. N Engl J Med 2002, 346: 1845-1853. 10.1056/NEJMoa013168

    Article  PubMed  Google Scholar 

  4. Cazeau S, Leclercq C, Lavergne T, Walker S, Varma C, Linde C, Garrigue S, Kappenberger L, Haywood GA, Santini M, Bailleul C, Daubert JC, Multisite Stimulation in Cardiomyopathies (MUSTIC) Study Investigators: Effects of multisite biventricualr pacing in patients with heart failure and intraventricular conduction delay. N Engl J Med 2001, 344: 873-880. 10.1056/NEJM200103223441202

    Article  CAS  PubMed  Google Scholar 

  5. Saxon LA, De Marco T, Schafer J, Chatterjee K, Kumar UN, Foster E: VIGOR Congestive Heart Failure Investigators. Effects of long-term biventricular stimulation for resynchronization on echocardiographic measures of remodeling. Circulatio 2002, 105: 1304-1310. 10.1161/hc1102.105730

    Article  Google Scholar 

  6. Sundell J, Engblom E, Koistinen J, Ylitalo A, Naum A, Stolen KQ, Kalliokoski R, Nekolla SG, Airaksinen KE, Bax JJ, Knuuti J: The effects of cardiac resynchronization therapy on left ventricular function, myocardial energetics, and metabolic reserve in patients with dilated cardiomyopathy and heart failure. J Am Coll Cardiol 2004,43(6):1027-1033. 10.1016/j.jacc.2003.10.044

    Article  PubMed  Google Scholar 

  7. Cleland JG, Daubert JC, Erdmann E, Freemantle N, Gras D, Kappenberger L, Tavazzi L, Cardiac Resynchronization-Heart Failure (CARE-HF) Study Investigators: The effect of cardiac resynchronization on morbidity and mortality in heart failure. N Engl J Med 2005,352(15):1539-1549. 10.1056/NEJMoa050496

    Article  CAS  PubMed  Google Scholar 

  8. Eugene M, Lascault G, Frank R, Fontaine G, Grosgogeat Y, Teillac A: Assessment of the optimal atrio-ventricular delay in DDD paced patients by impedance plethysmography. Eur Heart J 1989, 10: 250-255.

    CAS  PubMed  Google Scholar 

  9. Kindermann M, Fröhlig G, Doerr T, Schieffer H: Optimizing the AV delay in DDD pacemaker patients with high degree AV block: mitral valve doppler versus impedance cardiography. PACE 1997, 20: 2453-2462.

    Article  CAS  PubMed  Google Scholar 

  10. Ovsyshcher IE: Toward physiological pacing: optimization of cardiac hemodynamics by AV delay adjustment. PACE 1997, 20: 861-865.

    Article  CAS  PubMed  Google Scholar 

  11. Ishikawa T, Sumita S, Kimura K, Kikuchi M, Kosuge M, Kuji N, Endo T, Sugano T, Sigemasa T, Kobayaski I, Tochikubo I, Usui T: Prediction of optimal atrioventricular delay in patients with implanted DDD pacemakers. PACE 1999, 22: 1365-1371.

    Article  CAS  PubMed  Google Scholar 

  12. Von Knorre GH, Petzsch M, Ismer B: Approximation of optimal atrioventricular delay in DDD pacemaker patients with atrioventricular block by oesophageal electrocardiography (abstract). Eur Heart J 1996,17(Supplement):487.

    Google Scholar 

  13. Ritter Ph, Dib JC, Lelievre T: Quick determination of the optimal AV delay at rest in patients paced in DDD mode for complete AV block. (abstract). Eur J CPE 1994,4(2):A163.

    Google Scholar 

  14. Ritter P, Padeletti L, Gillio-Meina L, Gaggini G: Determination of the optimal atrioventricular delay in DDD pacing. Comparison between echo and peak endocardial acceleration measurements. Europace 1999, 1: 126-30. 10.1053/eupc.1998.0032

    Article  CAS  PubMed  Google Scholar 

  15. Occhetta E, Rognoni G, Perucca A, Aina F, Magnani A, Francalacci G, Rossi P: The functional and hemodynamic benefits of automatic atrioventricular interval delay in permanent atrial synchronized pacing. G Ital Cardiol 1993, 23: 877-886.

    CAS  PubMed  Google Scholar 

  16. Butter C, Auricchio A, Stellbrink C, Fleck E, Ding J, Yu Y, Huvelle E, Spinelli J, Pacing Therapy for Chronic Heart Failure II Study: Effect of resynchronization therapy stimulation site on the systolic function of heart failure patients. Circulation 2001, 104: 3026-3029.

    Article  CAS  PubMed  Google Scholar 

  17. Auricchio A, Stellbrink C, Sack S, Block M, Vogt J, Bakker P, Huth C, Schondube F, Wolfhard U, Bocker D, Krahnefeld O, Kirkels H, Pacing Therapies in Congestive Heart Failure (PATH-CHF) Study Group: Long-term clinical effect of hemodynamically optimized cardiac resynchronization therapy in patients with heart failure and ventricular conduction delay. J Am Coll Cardiol 2002, 39: 2026-2033. 10.1016/S0735-1097(02)01895-8

    Article  PubMed  Google Scholar 

  18. Kass D, 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.

    Article  CAS  PubMed  Google Scholar 

  19. Auricchio A, Stellbrink C, Block M, Sacks S, Vogt J, Bakker P, Klein H, Kramer A, Ding J, Salo R, Tockmann B, Pochet T, Spinelli J: Effect of pacing chamber and atrioventricular delay on acute systolic function of paced patients with congestive heart failure. Circulation 1999, 99: 2993-3001.

    Article  CAS  PubMed  Google Scholar 

  20. Stellbrink C, Breithardt OA, Diem B, Franke A, Pochet T, Salo R, Auricchio A: Acute effects of multisite pacing with different AV delays on diastolic and systolic function in congestive heart failure (abstract). PACE 1999, 22: 829.

    Article  Google Scholar 

  21. Meluzin J, Novak M, Mullerova J, Krejci J, Hude P, Eisenberger M, Dusek L, Dvorak I, Spinarova L: A fast and simple echocardiographic method of determination of the optimal atrioventricular delay in patients after biventricular stimulation. Pacing Clin Electrophysiol 2004, 27: 8-64. 10.1111/j.1540-8159.2004.00386.x

    Article  Google Scholar 

  22. Ismer B, von Knorre GH, Voß W, Körber T: Definition of the optimal atrioventricular delay by simultaneous measurement of electrocardiographic and doppler-echocardiographic parameters. Prog Biomed Res 2003, 7: 116-120.

    Google Scholar 

  23. Ismer B, von Knorre G, Voss W, Grille W, Klenke G, Kamesh Pulya, Koglek W, Suntinger A, Luessow H: Exercise induced sympathetic influences do not change interatrial conduction times in VDD and DDD pacing. PACE 1996, 19: 1786-1790.

    Article  CAS  PubMed  Google Scholar 

  24. Borges AC, Kivelitz D, Walde T, Reibis RK, Grohmann A, Panda A, Wernecke KD, Rutsch W, Hamm B, Baumann G: Apical tissue tracking echocardiography for characterization of regional left ventricular function: comparison with magnetic resonance imaging in patients after myocardial infarction. J Am Soc Echocardiogr 2003, 3: 254-262.

    Article  Google Scholar 

  25. Mele D, Pasanisi G, Heimdal A, Cittanti C, Guardigli G, Levine RA, Sutherland G, Ferrari R: Improved recognition of dysfunctioning myocardial segments by longitudinal strain rate versus velocity in patients with myocardial infarction. J Am Soc Echocardiogr 2004, 4: 313-321.

    Article  Google Scholar 

  26. Gorcsan J, Kanzaki H, Bazaz R, Dohi K, Schwartzman D: Usefulness of Echocardiografic Tissue Synchronization Imaging to Predict Acute Response to Cardiac Resynchronization Therapy. Am J Cardiol 2004, 93: 1178-1181. 10.1016/j.amjcard.2004.01.054

    Article  PubMed  Google Scholar 

  27. Yu CM, Zhang Q, Fung JW, 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(5):677-684. 10.1016/j.jacc.2004.12.003

    Article  PubMed  Google Scholar 

  28. Knebel F, Reibis RK, Bondke HJ, Witte J, Walde T, Eddicks S, Baumann G, Borges AC: Tissue Doppler echocardiography and biventricular pacing in heart failure: patient selection, procedural guidance, follow-up, quantification of success. Cardiovasc Ultrasound 2004,2(1):17. 10.1186/1476-7120-2-17

    Article  PubMed  PubMed Central  Google Scholar 

  29. Porciani MC, Dondina C, Macioce R, Demarchi G, Pieragnoli P, Musilli N, Colella A, Ricciardi G, Michelucci A, Padeletti L: Echocardiographic examination of atrioventricular and interventricular delay optimization in cardiac resynchronization therapy. Am J Cardiol 2005, 95: 1108-1110. 10.1016/j.amjcard.2005.01.028

    Article  PubMed  Google Scholar 

  30. Schuller H, Brandt J: The pacemaker syndrome: old and new causes. Clin Cardiol 1991, 14: 336-340.

    Article  CAS  PubMed  Google Scholar 

  31. Toda N, Ishikawa T, Nozawa N, Kobayashi I, Oghial H, Miyamoto K, Sumita S, Kimura K, Umemura S: Doppler index and plasma level of atrial natriuretic hormone are improved by optimizing atrioventricular delay in atrioventricular block patients with implanted DDD pacemakers. PACE 2001, 24: 1660-1663.

    Article  CAS  PubMed  Google Scholar 

  32. Breithardt OA, Sinha AM, Schwammenthal E, Bidaoui N, Markus KU, Franke A, Stellbrink C: Acute effects of cardiac resynchronization therapy on functional mitral regurgitation in advanced systolic heart failure. J Am Coll Cardiol 2003,41(5):765-770. 10.1016/S0735-1097(02)02937-6

    Article  PubMed  Google Scholar 

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Authors and Affiliations

  1. Medical Clinic for Cardiology, Angiology, Pulmology, Universitätsmedizin Berlin, Charité Campus Mitte, Germany

    Christoph Melzer, Fabian Knebel, Gert Baumann & Adrian C Borges

  2. Clinic for Internal Medicine, University of Rostock, Rostock, Germany

    Bruno Ismer, Hansjürgen Bondke & Christoph A Nienaber

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  1. Christoph Melzer
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The author(s) declare that they have no competing interests.

Authors' contributions

CM and FK have equally contributed to this publication. CM, BI, FK and ACB have designed and performed the study and have written the manuscript. HJB, CAN and GB have participated in the study design and coordination and have helped to draft the manuscript. All authors read and approved the final manuscript.

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Melzer, C., Knebel, F., Ismer, B. et al. Influence of the atrio-ventricular delay optimization on the intra left ventricular delay in cardiac resynchronization therapy. Cardiovasc Ultrasound 4, 5 (2006). https://doi.org/10.1186/1476-7120-4-5

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Keywords

  • Cardiac Resynchronization Therapy
  • Tissue Doppler Image
  • Chronic Heart Failure Patient
  • Biventricular Pace
  • Left Ventricular Dyssynchrony

Cardiovascular Ultrasound

ISSN: 1476-7120

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