intra-LV Dyssynchrony Research Articles

Equilibrium radionuclide angiography in evaluation of left ventricular mechanical dyssynchrony in patients with dilated cardiomyopathy: Comparison with electrocardiographic parameters and speckle-tracking echocardiography

Purpose of the Study:The purpose of this study was to study the role of equilibrium radionuclide angiography (ERNA) in the assessment of left ventricular (LV) mechanical dyssynchrony in patients with dilated cardiomyopathy (DCM), by correlating the findings with electrocardiographic parameters and speckle-tracking echocardiography (STE).Methods:This was a prospective observational study. A total of 55 patients with a mean age 42.5 ± 11 years (range: 19–61 years) diagnosed with DCM underwent ERNA and echocardiography sequentially. On ERNA, phase images of LV were obtained, and standard deviation of LV mean phase angle (SD LVmPA) was derived to quantify intra-LV mechanical dyssynchrony (ILVD). Similarly, on STE, “dyssynchrony index” was calculated as the standard deviation of time-to-peak systolic circumferential strain (SDCS) of the six mid-LV segments. The cutoff values used to define mechanical dyssynchrony were SD LVmPA >13.2° (or >27.1 ms) and SDCS >74 ms on ERNA and STE, respectively. The results obtained from the two modalities were then compared.Results:Speckle-tracking analysis could be done on the echocardiographic data of only 42 patients. Paired data from ERNA and STE studies of these 42 patients (26 males and 16 females) were compared, which showed no significant difference in the detection of ILVD (P = 0.125). The two modalities showed good agreement with Cohen's kappa value of 0.78 (P < 0.0001). SD LVmPA and SDCS values showed moderately strong linear correlation (ρ = 0.69; P < 0.0001). No significant association of mechanical dyssynchrony on ERNA or STE was found with QRS duration and with the presence or absence of left bundle branch block. ILVD was also found to be negatively correlated with LV ejection fraction.Conclusion:ERNA is comparable to STE for the assessment of LV mechanical dyssynchrony.

Myocardial Regional Interstitial Fibrosis is Associated With Left Intra-Ventricular Dyssynchrony in Patients With Heart Failure: A Cardiovascular Magnetic Resonance Study

Left ventricular (LV) dyssynchrony is associated with poor prognosis in patients with heart failure (HF). The mechanisms leading to LV dyssynchrony are not fully elucidated. This study evaluates whether myocardium regional variation in interstitial fibrosis is associated with LV dyssynchrony. Forty-two patients with systolic heart failure (SHF), 76 patients with heart failure with preserved ejection fraction (HFpEF) and 20 patients without HF received cardiovascular magnetic resonance imaging (MRI) study. LV was divided into 18 segments by short-axis view. In each segment, regional extracellular volume fraction (ECV) and the time taken to reach minimum regional volume (Tmv) were derived. Intra-LV dyssynchrony were represented by maximum difference (Dysyn_max) and standard deviation (Dysyn_sd) of all Tmv. The results showed that among the covariates, only age (1.87, 95% CI: 0.61–3.13, p = 0.004) and ECV (3.77, 95% CI: 2.72–4.81, p < 0.001) were positively associated with Tmv. The results remained robust in certain subgroups. In conclusion, we demonstrated that LV myocardium regional variation in interstitial fibrosis is closely related to LV intra-ventricular dyssynchrony irrespective of the LV global function. These data might help explain the pathophysiology of LV dyssynchrony and it’s underlying mechanisms leading to poor prognosis.

Hisian area and right ventricular apical pacing differently affect left atrial function: an intra-patients evaluation

Right ventricular apex (RVA) pacing has adverse effects on left atrial (LA) function and may contribute to atrial arrhythmias. The effects of Hisian area (HA) pacing on LA function are still lacking. The objective of this study is to assess the left ventricular (LV) electromechanical activation/relaxation, systolic (S), diastolic (D) phases, and their effects on LA function during pacing from HA and RVA. Thirty-seven patients with normal cardiac function underwent permanent HA pacing. In all patients, a RVA backup lead was added. The patients first underwent 3 months of HA pacing, followed by 3 months of RVA pacing. After each 3-month period, we compared by echocardiography: S-D LV electromechanical delay (S-D EMD), S-D intra-LV dyssynchrony, LV S-D phases, and their function evaluated by myocardial performance index (MPI) and mitral annular tissue Doppler early diastolic velocity (E'), pulmonary arterial systolic pressure (PASP), and LA function (LA phasic volumes and their emptying fraction). Right ventricular apex compared with HA pacing increased S-D EMD (P < 0.001) and intra-LV dyssynchrony (P < 0.001). As a consequence, a significant longer LV isovolumetric contraction time (P < 0.001) and LV isovolumetric relaxation time (P = 0.05) were measured during RVA compared with HA pacing, whereas LV ejection time was shorter (P = 0.033). Moreover, HA pacing resulted in significantly better MPI (P = 0.039), higher value of E' (P = 0.049), and lower PASP (P < 0.001). Finally, RVA compared with HA pacing was associated to higher LA volumes pre-atrial contraction (P = 0.001) and minimal volume (P = 0.003) with reduction in passive emptying fraction (P < 0.001) and total emptying fraction (P = 0.005). Hisian area compared with RVA pacing resulted in a more physiological LV electromechanical activation/relaxation and consequently better LA function.

Further Deterioration of LV Ejection Fraction and Mechanical Synchrony During RV Apical Pacing in Patients with Heart Failure and LBBB

Electrocardiographic left bundle branch block (LBBB) may be due to intrinsic disease of the left bundle branch or induced by right ventricular apical (RVA) pacing. Prior reports clearly delineate the derogatory impact of LBBB on left ventricular (LV) mechanical function but suggest equivalent impact between varieties. We hypothesized that their effects were disparate and performed a within-patient comparison to test this notion. Patients (n = 20) with heart failure, intrinsic LBBB, and an implanted pacing device with right atrial and RVA leads were studied. Each patient underwent transthoracic three-dimensional speckle-tracking echocardiography during atrial pacing (intrinsic LBBB) and short atrioventricular delay atrial-RVA pacing, and these studies were compared. Relative to intrinsic LBBB, RVA pacing-induced LBBB produced greater intra-LV and interventricular dyssynchrony, a deterioration in LV function, and a shift in the site of latest activation. In patients with heart failure and LBBB, acute RVA pacing induces greater mechanical dyssynchrony and further impairs LV function.

Pre‐ and Intra‐Procedural Predictors of Reverse Remodeling After Cardiac Resynchronization Therapy: An MRI Study

Response rate after cardiac resynchronization therapy (CRT) remains suboptimal. We sought to identify pre- and intraprocedural predictors of response using MRI. Sixty patients underwent MRI before CRT. Left ventricular (LV) volumes and ejection fraction were assessed on cine images. Intra-LV dyssynchrony was defined as the maximal delay between first peaks of radial wall motion over 20 segments. Myocardial scar extent was quantified using delayed-enhanced MRI. After CRT, the paced LV segment was characterized on preprocedural MRI with respect to presence of scar and mechanical delay, the latter being quantified using time to first peak of wall motion, expressed in percentage of the total LV activation. Echocardiography was performed before and 6 months after CRT to quantify reverse remodeling (RR). Mean RR at 6 months was 30±29% of baseline LV end-systolic volume. At univariate analysis, RR related to baseline LV end-diastolic and end-systolic volumes (R(2) = 0.101, P = 0.01; R(2) = 0.072, P = 0.04), intra-LV mechanical dyssynchrony (R(2) = 0.351, P<0.0001), scar extent (R(2) = 0.273, P< 0.0001), and presence of scar at pacing site (R(2) = 0.100, P = 0.01). QRS duration and mechanical delay at pacing site were not found related to RR (R(2) = 0.041, P = 0.12 and R(2) = 0.012, P = 0.4, respectively). At multivariate analysis intra-LV mechanical dyssynchrony, scar extent, and LV end-diastolic volume were independent predictors of RR (R(2) = 0.307, P = 0.001; R(2) = 0.096, P = 0.002, R(2) = 0.078, P = 0.005, respectively). Intra-LV dyssynchrony and scar extent are independent predictors of RR after CRT. Scar at pacing site is associated to a lesser response to CRT. Mechanical delay at this site has no impact on the response.

A new integrated approach to improve left ventricular electromechanical activation during right ventricular septal pacing

The deleterious effects of apical right ventricular pacing has fostered the utilization of alternative pacing sites. Although right ventricular septal (RVS) sites are commonly used, the results have been controversial because of poor standardization of lead position by fluoroscopy. This study investigated the utility of a new RVS pacing technique based on the combination of fluoroscopy (F), and electrophysiological mapping (F + EP). Left ventricular (LV) electromechanical activation was determined in patients undergoing RVS pacing and the results of the F + EP approach were compared with those derived from standard F alone. Between December 2008 and November 2010 we enrolled 156 consecutive patients undergoing permanent RVS pacing. The standard F approach was used in 93 patients and the F + EP technique was applied to 63 patients. Electromechanical activation was assessed by: (i) electromechanical latency (EML) interval measured from the QRS onset to the mechanical activation of the basal LV and (ii) intra-LV dyssynchrony measured as the interval from the earliest to the latest LV basal motion. Intra-LV dyssynchrony was found in 46.2% patients in the F group compared with 15.9% in the group F + EP (P < 0.001). The F group demonstrated a significantly higher degree of intra-LV dyssynchrony than F + EP group (43.9 ± 24.3 vs. 26.5 ± 15.4 ms; P < 0.001). The F group exhibited a significantly higher EML duration compared with the F + EP group (215.8 ± 25.3 vs. 195.1 ± 17.4 ms; P < 0.001). During RVS pacing, the F + EP approach provides a more physiological LV activation than the standard F technique. The prognostic significance of these short-term findings needs to be correlated with long-term data.

Dyssynchrony in Obese Subjects without a History of Cardiac Disease Using Velocity Vector Imaging

The aim of this study was to examine the occurrence of intra-left ventricular (LV) dyssynchrony in obese versus nonobese subjects without known cardiac disease using Velocity Vector Imaging (VVI). One hundred ninety consecutive subjects with no known cardiac disease had their echocardiograms analyzed using VVI after excluding subjects with QRS durations>120 msec or LV ejection fractions<55%. Study subjects were divided into two groups on the basis of body mass index: obese (>30 kg/m2) and nonobese (<30 kg/m2). The final cohort included 136 subjects (74 obese; 32% women; mean age, 55±16 years). The occurrence of intra-LV dyssynchrony was higher in the obese group compared with the nonobese group. There was an increased prevalence of intra-LV dyssynchrony in obese subjects, especially longitudinal and radial dyssynchrony. This dyssynchrony may signal a mechanism by which obesity predisposes to the development of heart failure.

Test–re-test reproducibility of Doppler echocardiography for assessment of electromechanical dyssynchrony: Implications for heart failure clinic

Reproducibility of Doppler echocardiography for assessment of inter-ventricular and intra-left ventricular (LV) dyssynchrony, and its clinical implications, have not been established. Twenty-eight subjects (heart failure stages A-C, 61% with QRS ≥ 120 ms, ejection fraction (EF) ≤ 35%) underwent two consecutive echo-studies within 24h to evaluate test-re-test reproducibility of inter-ventricular electromechanical delay (VV delay, by traditional pulsed-Doppler), and intra-LV electromechanical delay between opposite LV walls by color-coded Doppler tissue-velocity (COLOR-DTI), and by pulsed-Doppler tissue spectrum (PW-DTI). Reproducibility of LV internal diastolic diameter (LVIDD) and of EF (by Simpson's method) assessments was evaluated contextually for reference. Intra-study and inter-study reproducibility of inter-ventricular and intra-LV electromechanical dyssynchrony was in general good, and comparable to the reproducibility of LVIDD and EF assessments. Between-study reproducibility of PW-TDI method was fair, but showed poor agreement with COLOR-TDI method. In repeated studies, agreement of significant electromechanical delay by COLOR-TDI was comparable to the agreement of EF ≤ 35%. In the 5 patients who had simultaneously large QRS, EF ≤ 35%, and significant inter- and intra-ventricular dyssynchrony at study #1, 3 had EF 36-40% and 1 showed no significant dyssynchrony by study #2. In serial echocardiographic studies, Doppler echocardiography showed a good test-re-test reproducibility for the identification of significant electromechanical delay. Planimetry for EF assessment was a source of variability as relevant as Doppler echocardiography, but COLOR-DTI may add meaningful and reproducible information to QRS duration for cardiac-resynchronization therapy.

Long‐Term Mechanical Consequences of Permanent Right Ventricular Pacing: Effect of Pacing Site

Long-term right ventricular apical (RVA) pacing has been associated with adverse effects on left ventricular systolic function; however, the comparative effects of right ventricular outflow tract (RVOT) pacing are unknown. Our aim was therefore to examine the long-term effects of septal RVOT versus RVA pacing on left ventricular and atrial structure and function. Fifty-eight patients who were prospectively randomized to long-term pacing either from the right ventricular apex or RVOT septum were studied echocardiographically. Left ventricular (LV) and atrial (LA) volumes were measured. LV 2D strain and tissue velocity images were analyzed to measure 18-segment time-to-peak longitudinal systolic strain and 12-segment time-to-peak systolic tissue velocity. Intra-LV synchrony was assessed by their respective standard deviations. Interventricular mechanical delay was measured as the difference in time-to-onset of systolic flow in the RVOT and LV outflow tract. Septal A' was measured using tissue velocity images. Following 29 ± 10 months pacing, there was a significant difference in LV ejection fraction (P < 0.001), LV end-systolic volume (P = 0.007), and LA volume (P = 0.02) favoring the RVOT-paced group over the RVA-paced patients. RVA-pacing was associated with greater interventricular mechanical dyssynchrony and intra-LV dyssynchrony than RVOT-pacing. Septal A' was adversely affected by intra-LV dyssynchrony (P < 0.05). Long-term RVOT-pacing was associated with superior indices of LV structure and function compared with RVA-pacing, and was associated with less adverse LA remodeling. If pacing cannot be avoided, the RVOT septum may be the preferred site for right ventricular pacing.

Variability of Left Ventricular Electromechanical Activation during Right Ventricular Pacing: Implications for the Selection of the Optimal Pacing Site

The right ventricular septum (RVS) and Hisian area (HA) are considered more "physiological" pacing sites than right ventricular apex (RVA). Studies comparing RVS to RVA sites have produced controversial results. There are no data about variability of electromechanical activation obtained by an approach using fluoroscopy and electrophysiological markers. This study compared the variability of left ventricular (LV) electromechanical activation in patients undergoing short-term RVA and RVS with that measured during HA pacing based on fluoroscopy and electrophysiological markers. Tissue Doppler echocardiography was performed in 142 patients before and after RVA (54), RVS (44), and HA (44) pacing. Electromechanical activation was assessed by: (1) electromechanical latency (EML)-interval between QRS onset and mechanical activation of basal LV; (2) intra-LV dyssynchrony (intra-LV)-interval between earliest to the latest LV basal motion. The intra- and interpatients variability among pacing groups were assessed. Pacing from RVA showed longer EML and higher degree of intra-LV than RVS and HA pacing. RVA and RVS showed a higher variability than HA pacing with regard to intrapatient changes of EML (RVA vs RVS, P = 0.4; RVS vs HA, P = 0.01, RVA vs HA, P = 0.0002) and intra-LV (RVA vs RVS, P = 0.2; RVS vs HA, P = 0.04; RVA vs HA, P = 0.005). Similar results were found in interpatients variability from paced-values. RVA and RVS pacing produce a variable effect on LV electromechanical activation that is significantly more pronounced than HA pacing. A pacing site such as HA selected by fluoroscopic and electrophysiological markers maintains baseline and homogeneous LV activation pattern.

Impact of right ventricular contractility on left ventricular dyssynchrony in patients with chronic systolic heart failure

Background Cardiac resynchronization therapy (CRT) is an important therapeutic approach for patients with symptomatic heart failure. The assessment of mechanical dyssynchrony, however, remains an issue. Little data are available regarding the influence of the right ventricle (RV) on left ventricle (LV) mechanical dyssynchrony as assessed by echocardiography. Aims We sought to assess the impact of RV contractility on LV function and dyssynchrony. Methods A total of 40 patients with congestive heart failure were analyzed. Twenty had RV dysfunction, as defined by a tricuspid annular systolic peak of tissue Doppler (SaRV) < 11.5 cm/s, while the remaining 20 had SaRV>11.5 cm/s. All patients underwent echocardiography in order to determine RV function, LV function, and dyssynchrony. Results The two populations were similar regarding diastolic function, atrio-ventricular conduction and interventricular dyssynchrony. Patients with RV dysfunction showed significantly more severe LV longitudinal dyssynchrony (130 ± 103 ms vs. 62 ± 59 ms; p = 0.01). In addition, SaRV (systolic peak recorded at the tricuspid annulus) was correlated with LV longitudinal dyssynchrony ( r = 0.47; p = 0.001). In contrast, LV radial contractility and dyssynchrony (103 ± 110 ms vs. 100 ± 78 ms; p = 0.5) were not affected by RV function. Conclusion Quantitative analysis of RV function is important when assessing LV function and dyssynchrony in patients with systolic heart failure. RV function is associated with intra-LV dyssynchrony, particularly when considering longitudinal function.

Implication of QRS Prolongation and Its Relation to Mechanical Dyssynchrony in Idiopathic Dilated Cardiomyopathy in Childhood

We explored the role of QRS prolongation (>or=120 ms) and its relation to mechanical dyssynchrony and outcomes in childhood idiopathic dilated cardiomyopathy (IDC). A total of 89 patients <or=18 years old diagnosed as having IDC (21 days to 26 years of follow-up) were investigated. In 20 survivors with residual left ventricular (LV) dysfunction, mechanical (interventricular and intra-LV) dyssynchrony was assessed. The SD of time from the beginning of QRS prolongation to peak systolic contraction was measured in 12 LV segments by tissue Doppler imaging. A cut-off value >32.6 ms was used to define intra-LV dyssynchrony. The 1- and 5-year survivals were 70% and 53%, respectively. Requirement of intravenous inotropes at follow-up (hazard ratio 3.10) and initial LV ejection fraction (hazard ratio 0.95) were major prognostic factors. QRS prolongation, primarily left bundle branch block, was identified in 16 patients (18%) and tended to increase the risk of requiring inotropes. Moreover, none of those with QRS prolongation regained normal cardiac function at follow-up. Two patients with QRS prolongation showed marked improvement in cardiac function after cardiac resynchronization therapy. Mechanical dyssynchrony was noted in all patients with QRS prolongation and in 8% (interventricular) or 38% (intra-LV) of those without. In conclusion, QRS prolongation was common in childhood IDC and was possibly associated with persistent LV dysfunction and worse cardiac outcome. Mechanical (inter- and intraventricular) dyssynchrony was highly prevalent in those with QRS prolongation and was still often observed in those without.

Efficacy of LOw-dose DObutamine Stress-Echocardiography to predict Cardiac Resynchronization Therapy Response (LODO-CRT) multicenter prospective study—Design and rationale

Although cardiac resynchronization therapy (CRT) has a well-demonstrated therapeutic effect in selected patients with advanced heart failure on optimized drug therapy, nonresponder rate remains high. The LODO-CRT is designed to improve patient selection for CRT. Design and rationale of this study are presented herein. LODO-CRT is a multicenter prospective study, started in late 2006, that enrolls patients with conventional indications for CRT (symptomatic stable New York Heart Association class III-IV on optimized drug therapy, QRS > or =120 milliseconds, left ventricular [LV] dilatation, LV ejection fraction < or =35%). This study is designed to assess the predictive value of LV contractile reserve (LVCR), determined through dobutamine stress echocardiography (defined as an LV ejection fraction increase >5 units), in predicting CRT response during follow-up. Assessment of CRT effects will follow 2 sequential phases: in phase 1, CRT response end point is defined as LV end-systolic volume reduction > or =10% at 6 months; in phase 2, both LV end-systolic volume reduction and clinical status via a clinical composite score will be evaluated at 12 months follow-up. Predictive value of LVCR will be compared to other measures, such as LV dyssynchrony measures, through adjusted multivariable analysis. For the purpose of the study, target patient number is 270 (with 95% confidence, 80% power, alpha < or = .05). Enrollment should be complete by the end of 2008. The LODO-CRT trial is testing the hypothesis that LVCR assessment, using low-dose dobutamine stress echocardiography test, should effectively predict positive response to CRT both in terms of the reverse remodeling process as well as favorable long-term clinical outcome. Moreover, the predictive value of LVCR will be compared to that of conventional intra-LV dyssynchrony measures.

Significance of QRS morphology in determining the prevalence of mechanical dyssynchrony in heart failure patients eligible for cardiac resynchronization: particular focus on patients with right bundle branch block with and without coexistent left-sided conduction defects

The aim of this study was to assess the significance of QRS morphology in determining the prevalence of mechanical dyssynchrony in heart failure (HF) patients considered eligible for cardiac resynchronization. A total of 200 consecutive HF patients (158 males, mean age 56 +/- 13.5 years) with standard indications for cardiac resynchronization therapy (CRT) were evaluated prospectively. The prevalence of an interventricular mechanical delay > or = 40 ms was lower in patients with pure right bundle branch block (RBBB) than that in those with RBBB plus left fascicular hemiblock (RBBB-LFH) and those with left bundle branch block (LBBB) (33 vs. 50 vs. 54%, P = 0.05). A maximal difference in peak myocardial systolic velocity among all 12 segments (Ts) > 100 ms was found in 63% of the patients with LBBB, whereas it was present in 31% of the patients with pure RBBB and in 42% of those with RBBB-LFH (P < 0.001). A standard deviation of Ts (Ts-SD) > 34 ms was present in 58% of the LBBB subjects, but in only 29% and 42% of the patients with pure RBBB and RBBB-LFH, respectively (P < 0.001). Intraventricular dyssynchrony, however, was not different in patients with pure RBBB and in those with RBBB-LFH in terms of maximal difference in Ts (P = 0.25) and Ts-SD (P = 0.17). Although LBBB was more often associated with intraventricular dyssynchrony, ECG sign of additional left ventricular (LV) conduction delay is not a helpful tool for the identification of intra-LV mechanical dyssynchrony in HF patients with RBBB who would benefit from CRT.

Abstract 3286: Prediction for Long-term Effect Of Cardiac Resynchronization Therapy: Comparison Between Tissue Doppler Imaging And Speckle Tracking Imaging

Recent studies have demonstrated that the septal-to-posterior motion delay (SPWMD) assessed by M-mode echo and the longitudinal intra-LV dyssynchrony assessed by tissue Doppler imaging (TDI) can predict chronic effects of cardiac resynchronization therapy (CRT). A newly developed 2D speckle tracking imaging (STI) has enabled assessment of not only longitudinal but circumferential regional strain of LV. We investigated the usefulness of STI in selecting patients for CRT. Methods: Fifty-one patients with heart failure symptoms and QRS duration&gt;120 ms underwent standard echocardiography, TDI and STI before CRT. Time to peak systolic velocity was measured in 12 basal and mid LV segments in apical views by TDI. The time difference between the basal septal and the basal lateral segments was calculated (TDI-SLPVD).The standard deviation of those among 12 segments was calculated (TDI-SD). Time to peak circumferential strain, radial strain and longitudinal strain were measured in basal segments in parasternal short axis and apical views by STI. The time difference between the septal and the lateral segments was calculated (CS-SL, RS-SL and LS-SL). A responder to CRT was defined as a patient whose NYHA class improved by &gt;1 class and whose LVESV reduced by &gt;10% at 6 months after CRT. Results: Thirty-six patients (71%) responded to CRT. CS-SL showed high sensitivity and specificity for predicting the responders at a cut-off point of 124 ms (Table ). The area under the ROC curve (AUC) of CS-SL was larger than that of QRS duration, SPWMD, TDI-SLPVD, TDI-SD, RS-SL and LS-SL. Conclusion: Assessment of circumferential dyssynchrony using STI seems useful in selecting patients for CRT.

The interaction of interventricular pacing intervals and left ventricular lead position during temporary biventricular pacing evaluated by tissue Doppler imaging

Objective:To determine the effects of interventricular pacing interval and left ventricular (LV) pacing site on ventricular dyssynchrony and function at baseline and during biventricular pacing, using tissue Doppler imaging.Methods:Using an...

Left ventricular electromechanical delay in patients with heart failure and normal QRS duration and in patients with right and left bundle branch block

We sought to define the reference values of intra-left ventricular (LV) electromechanical delay (EMD), and to assess the prevalence (and pattern) of intra-LV dyssynchrony in patients with heart failure (HF) and normal QRS and in patients with right and left bundle branch block. We used tissue Doppler imaging echocardiography and a six-LV wall model to study LV EMD in 103 patients [41 with HF and normal QRS, 22 with right bundle branch block (RBBB), and 40 with left bundle branch block (LBBB)], and in 59 controls. In controls, the median intra-LV EMD was 17 ms, (inter-quartile range 13-30); 95% of controls had a value < or =41 ms. Patients showed a longer intra-LV EMD than controls: 33 ms (20-57) in patients with normal QRS, 32 ms (23-50) in RBBB patients, and 50 ms (30-94) in LBBB patients. Intra-LV dyssynchrony (defined as intra-LV EMD >41 ms) was present in 39, 36, and 60% of the patients, respectively. On average, HF patients showed the same pattern of activation as controls, from the septum to the posterior wall, but activation times were significantly prolonged. In RBBB patients the activation sequence was directed from inferior to anterior and in LBBB from anterior to inferior wall. Left ventricular dyssynchrony was present in several patients with HF and normal QRS, and in patients with RBBB; conversely, 40% of LBBB patients showed values of LV EMD within the normal range. Left ventricular activation sequence was different between groups. Assessment of LV synchronicity by means of imaging techniques may be more important than QRS duration or morphology in selecting patients for cardiac resynchronization treatment.

Gated blood pool tomoscintigraphy with 4-dimensional optical flow motion analysis quantifies left ventricular mechanical activation and synchronization

Gated blood pool tomoscintigraphy has the unique capacity to accurately assess myocardial motion in paced patients. Our goal was to develop a precise radionuclide angiography analysis of cardiac dynamics to evaluate ventricular synchronization in patients undergoing biventricular pacing. On the basis of a 4-dimensional deformable motion estimation algorithm, we developed a protocol allowing estimation of motion fields after gated blood pool tomoscintigraphy. We measured the mechanical activation times for 17 left ventricular (LV) segments and determined the main types of contraction pattern in 10 normal subjects, 17 patients with dilated cardiomyopathy, and 12 resynchronized patients. We analyzed intra-LV dyssynchrony: apex to base, septum to lateral wall, and anterior wall to inferior wall. Three-dimensional measurements of intra-LV activation time (r > .80, P < .001) and LV ejection fraction (r > 0.90, P < .0001) are linearly correlated to 2-dimensional values. LV contraction follows the electrical activation pattern. In normal subjects the anteroseptal and anterior segments are first activated, followed by the apex and inferolateral segments. In resynchronized patients contraction begins with the lateral and apicoseptal segments in correspondence to the LV and right ventricular lead implantation. By measuring mechanical activation times, this technique allows for the analysis of the regional synchronous contraction. This may help to assess the variation of the activation pattern according to the cardiomyopathy type and the role of septal resynchronization in ventricular functional recovery.

Echocardiographic parameters of ventricular dyssynchrony validation in patients with heart failure using sequential biventricular pacing

We sought to evaluate the relationship between hemodynamic and ventricular dyssynchrony parameters in patients undergoing simultaneous and sequential biventricular pacing (BVP). Various echocardiographic parameters of ventricular dyssynchrony have been proposed to screen and optimize BVP therapy. Forty-one patients with heart failure undergoing BVP implantation were studied. Echocardiography coupled with tissue tracking and pulsed Doppler tissue imaging (DTI) was performed before and after BVP implantation and after three months of optimized BVP. Indexes of inter- or intraventricular dyssynchrony were correlated with hemodynamic changes during simultaneous and sequential BVP (10 intervals of right ventricular [RV] or left ventricular [LV] pre-excitation). Variations in intra-LV delay(peak), intra-LV delay(onset), and index of LV dyssynchrony measured by pulsed DTI were highly correlated with those of cardiac output (r = -0.67, r = -0.64, and r = -0.67, respectively; p < 0.001) and mitral regurgitation (r = 0.68, r = 0.63, and r = 0.68, respectively; p < 0.001), whereas variations in the extent of myocardium displaying delayed longitudinal contraction (r = -0.48 and r = 0.51, respectively; p < 0.05) and the variations in septal-to-posterior wall motion delay (r = -0.41, p < 0.05 and r = 0.24, p = NS, respectively) were less correlated. The changes in interventricular dyssynchrony were not significantly correlated (p = NS). Compared with simultaneous BVP, individually optimized sequential BVP significantly increased cardiac output (p < 0.01), decreased mitral regurgitation (p < 0.05), and improved all parameters of intra-LV dyssynchrony (p < 0.01). At three months, a significant reverse mechanical LV remodeling was observed with significantly decreased LV volumes (p < 0.01) associated with an increased LV ejection fraction (p = 0.035). Specific echocardiographic measurements of ventricular dyssynchrony are highly correlated with hemodynamic changes and may be a useful adjunct in the selection and optimization of BVP. Individually optimized sequential BVP provided a significant early hemodynamic improvement compared with simultaneous BVP.

Reliability of QRS duration and morphology on surface electrocardiogram to identify ventricular dyssynchrony in patients with idiopathic dilated cardiomyopathy

Using Fourier phase analysis of equilibrium radionuclide angiography in both ventricles, inter- and intraventricular delays were correlated with QRS morphology and duration in 103 patients with idiopathic dilated cardiomyopathy. We found that left bundle branch block on the left axis may reflect a high intra-left ventricular dyssynchrony. A precise evaluation of the dyssynchrony appears useful because a high proportion of patients with incomplete bundle branch block, left anterior hemiblock, or “normal” QRS exhibit a marked intra-LV dyssynchrony and may respond to cardiac resynchronization therapy.