Left Ventricular Preactivation Research Articles

Manual Intracardiac Electrogram Method Is Accurate Alternative to Echocardiography for Atrioventricular and Interventricular Optimization in Cardiac Resynchronization Therapy.

Some manufacturers do not provide automated intracardiac electrogram method (IEGM) systems for atrioventricular (AV) and interventricular (VV) delay optimization in cardiac resynchronization therapy (CRT). We aimed to evaluate the accuracy of manual IEGM method in 48 patients previously implanted with Medtronic Syncra CRT. All patients underwent standard device interrogation followed by CRT optimization by IEGM method and by echocardiography one month after implantation. The patient mean age was 60.7±11.8 years and there were 33 (68.8%) males. After CRT implantation, the left ventricular ejection fraction increased from 28.0±7.9% to 39.1±11.0% (p<0.001). Optimal aortic flow Velocity Time Integral (aVTI) was obtained when VV was set to 20-50 ms left ventricular pre-activation. There was a strong correlation between VV values determined by echocardiography and IEGM (R=0.823, p<0.001). We found no significant difference in AV, VV and aVTI values between echocardiography and IEGM method. However, IEGM was significantly less time-consuming than echocardiography [20 (10-28) vs. 40 (35-60) minutes, p<0.001]. Manual IEGM method may be good alternative to echocardiography and automated IEGM method. It also emphasizes the need for implementation of automated IEGM systems in as many CRT devices as possible.

The roles of the Q (q) wave in lead I and QRS frontal axis for diagnosing loss of left ventricular capture during cardiac resynchronization therapy.

Loss of left ventricular (LV) capture may lead to deterioration of heart failure in patients with cardiac resynchronization therapy (CRT). Recognition of loss of LV capture in time is important in clinical practice. A total of 422 electrocardiograms were acquired and analyzed from 53 CRT patients at 8 different pacing settings (LV only, right ventricle [RV] only, biventricular [BV] pacing with LV preactivation of 60, 40, 20, and 0 milliseconds and RV preactivation of 20 and 40 milliseconds). A modified Ammann algorithm by adding a third step-presence of Q (q, or QS) wave-to the original 2-step Ammann algorithm and a QRS axis shift method were devised to identify the loss of LV capture. The accuracy of modified Ammann algorithm was significantly higher than that of Ammann algorithm (78.9% vs. 69.1%, P < 0.001). The accuracy of the axis shift method was 66.4%, which was significantly lower than the modified Ammann algorithm (P < 0.001) and similar to the original one (P = 0.412). However, in the ECGs with QRS axis shift, 96.8% were correctly classified. LV preactivation or simultaneous BV activation and LV lead positioned in nonposterior or noninferior wall could elevate the accuracies of the modified Ammann algorithm and the QRS axis shift method. The accuracy of the modified Ammann algorithm is greatly improved. The QRS axis shift method can help diagnose LV capture. The LV preactivation, or simultaneous BV activation and LV lead positioned in nonposterior or noninferior wall can increase the diagnostic power of the modified Ammann algorithm and QRS axis shift method.

Cardiac resynchronization therapy beyond nominal settings: who needs individual programming of the atrioventricular and interventricular delay?

This study aimed to determine the additional acute haemodynamic effect of atrioventricular (AV) and interventricular (VV) delay optimization compared with current nominal cardiac resynchronization therapy (CRT) device settings, and to explore whether clinical characteristics correlate to the effect of optimization. Fifty CRT patients were prospectively enrolled. The optimal AV and VV delays were guided by relative improvement in maximum rate of left ventricular (LV) pressure rise (%dP/dt(max)). A significant improvement in %dP/dt(max) was obtained by optimization in 23-33% (sensed AV delay), 32-57% (paced AV delay), and 45% of patients (VV delay). Adjustment of the device nominal VV delay from 0 to 40 ms LV pre-activation would diminish the proportion of patients with additional effect of individual optimization from 45 to 15%. Heart failure aetiology [ischaemic 2 ± 2 vs. non-ischaemic 1 ± 1 percentage points (PP) %dP/dt(max), P= 0.013], gender (men 2 ± 2 vs. women 1 ± 1 PP %dP/dt(max), P= 0.012) and intrinsic PR interval (R= 0.49, P= 0.002) correlated to the degree of effect of AV delay optimization. Women yielded more effect of VV delay optimization (4 ± 3 vs. 2 ± 1 PP %dP/dt(max), P= 0.026). Compared with the best of the currently available device nominal AV and VV delays, 23-45% of CRT patients can yield additional acute haemodynamic effect by individual optimization of the delays. A new nominal VV delay of 40 ms LV pre-activation is recommended. Male gender, ischaemic aetiology, and longer PR interval are associated with a larger effect of individual optimization.

The ECG in Cardiac Resynchronization Therapy: Influence of Left and Right Ventricular Preactivation and Relation to Acute Response

The aims of this study were to compare ECG signs of biventricular electrical resynchronization during cardiac resynchronization therapy (CRT) with various interventricular (VV) delays and to correlate these and other ECG characteristics with the acute hemodynamic benefit of CRT. Thirty-four patients with heart failure and a left bundle branch block (LBBB) pattern were prospectively enrolled. A 12-lead surface ECG and the relative improvement in left ventricular (LV) dP/dt(max) (the maximum rate of pressure rise) were recorded at baseline and during CRT with VV delays varying from 80 ms LV preactivation to 40 ms right ventricular (RV) preactivation. Rightward QRS-axis shift occurred in 71-80% among all VV delays. Activation reversal to dominant negative in leads I/aVL was progressively observed at increasing LV preactivation (53-65%) and less (18-22%) during RV preactivation. Activation reversal to dominant positive in leads V1/V2 was observed in 21-27% during LV preactivation and in 6-15% during RV preactivation. Higher acute response to CRT was independently predicted by a complete LBBB at baseline (regression coefficient B = 7.7 [0.3-15.0], P = 0.042), later timing of LV depolarization within the QRS at baseline (Q-LVsense: B = 0.2 [0.1-0.3], P = 0.002), and biventricular electrical resynchronization during CRT as evidenced by activation reversal in leads I/aVL (B = 9.9 [3.2-16.6], P = 0.005). ECG signs of biventricular electrical resynchronization are present over a wide range of LV preactivated VV delays but to a lesser extent during RV preactivation. The presence of complete LBBB and longer Q-LVsense at baseline and signs of biventricular electrical resynchronization during CRT predict higher acute hemodynamic response.

Acute Beneficial Hemodynamic Effects of a Novel 3D-Echocardiographic Optimization Protocol in Cardiac Resynchronization Therapy

BackgroundPost-implantation therapies to optimize cardiac resynchronization therapy (CRT) focus on adjustments of the atrio-ventricular (AV) delay and ventricular-to-ventricular (VV) interval. However, there is little consensus on how to achieve best resynchronization with these parameters. The aim of this study was to examine a novel combination of doppler echocardiography (DE) and three-dimensional echocardiography (3DE) for individualized optimization of device based AV delays and VV intervals compared to empiric programming.Methods25 recipients of CRT (male: 56%, mean age: 67 years) were included in this study. Ejection fraction (EF), the primary outcome parameter, and left ventricular (LV) dimensions were evaluated by 3DE before CRT (baseline), after AV delay optimization while pacing the ventricles simultaneously (empiric VV interval programming) and after individualized VV interval optimization. For AV delay optimization aortic velocity time integral (AoVTI) was examined in eight different AV delays, and the AV delay with the highest AoVTI was programmed. For individualized VV interval optimization 3DE full-volume datasets of the left ventricle were obtained and analyzed to derive a systolic dyssynchrony index (SDI), calculated from the dispersion of time to minimal regional volume for all 16 LV segments. Consecutively, SDI was evaluated in six different VV intervals (including LV or right ventricular preactivation), and the VV interval with the lowest SDI was programmed (individualized optimization).ResultsEF increased from baseline 23±7% to 30±8 (p<0.001) after AV delay optimization and to 32±8% (p<0.05) after individualized optimization with an associated decrease of end-systolic volume from a baseline of 138±60 ml to 115±42 ml (p<0.001). Moreover, individualized optimization significantly reduced SDI from a baseline of 14.3±5.5% to 6.1±2.6% (p<0.001).ConclusionsCompared with empiric programming of biventricular pacemakers, individualized echocardiographic optimization with the integration of 3-dimensional indices into the optimization protocol acutely improved LV systolic function and decreased ESV and can be used to select the optimal AV delay and VV interval in CRT.

Dyssynchrony parameter-guided interventricular delay programming

Interventricular (VV) delay optimization for cardiac resynchronization therapy (CRT) is recommended by current guidelines and several algorithms have been proposed. So far, however, no gold standard has been established in the clinical routine. We hypothesized that dyssynchrony parameter assessment might guide VV delay optimization and investigated whether dyssynchrony parameter changes induced by sequential biventricular pacing follow a predictable pattern. We determined intra- and interventricular dyssynchrony in 80 CRT patients by echocardiographic quantification of the interventricular mechanical delay and the septal-lateral time to peak systolic velocity delay. Dyssynchrony parameters were assessed during simultaneous biventricular pacing as well as during sequential biventricular pacing with a right ventricular (RV) or left ventricular (LV) preactivation of 40 ms. Simultaneous biventricular pacing significantly improved inter- and intraventricular dyssynchrony parameters compared with preoperative baseline measurements. In general, dyssynchrony parameter changes induced by sequential biventricular pacing showed high interindividual variance and did not follow a predictable pattern. Intra- or interventricular dyssynchrony persisted during simultaneous biventricular pacing in 39 and 19% of our patients, respectively. Neither RV nor LV preactivation significantly decreased the number of patients with persistent intraventricular dyssynchrony. In contrast, LV preactivation significantly reduced the prevalence of interventricular dyssynchrony by 80%. Left ventricular preactivation effectively ameliorates interventricular dyssynchrony, which persists in almost one in five CRT patients. Assessment of interventricular dyssynchrony and consecutive programming of LV preactivation in patients with persistent interventricular dyssynchrony may represent a pragmatic and time-effective approach to improve CRT in patients with inferior response.

Comparison of Hemodynamic versus Dyssynchrony Assessment for Interventricular Delay Optimization with Echocardiography in Cardiac Resynchronization Therapy

Best practice for cardiac resynchronization therapy (CRT) device optimization is not established. This study compared Tissue Doppler Imaging (TDI) to study left ventricular (LV) synchrony and left ventricular outflow tract velocity-time integral (LVOT VTI) to assess hemodynamic performance. LVOT VTI and LV synchrony were tested in 50 patients at three interventricular (VV) delays (LV preactivation at -30 ms, simultaneous biventricular pacing, and right ventricular preactivation at +30 ms), selecting the highest VTI and the greatest degree of superposition of the displacement curves, respectively, as the optimum VV delay. In 39 patients (81%), both techniques agreed (Kappa = 0.65, p < 0.0001) on the optimum VV delay. LV preactivation (VV - 30) was the interval most frequently chosen. Both TDI and LVOT VTI are useful CRT programming methods for VV optimization. The best hemodynamic response correlates with the best synchrony. In most patients, the optimum VV interval is LV preactivation.

Cardiac resynchronization therapy; the importance of evaluating cardiac metabolism

Cardiac resynchronization therapy; the importance of evaluating cardiac metabolism

Optimization of the Interventricular Delay in Cardiac Resynchronization Therapy Using the QRS Width

Optimization of the interventricular pacing delay (VV) in cardiac resynchronization therapy is time-consuming and not routinely performed. The aim of the present study was to compare the acute hemodynamic response obtained by different VV programming methods. Several methods for optimizing the VV using electrocardiographic or echocardiographic measurements were performed. The effect of programming an empirical prefixed VV of 0 ms was also evaluated. Invasive first derivative of left ventricular (LV) pressure over time (dP/dt max) was measured at several VV values, and the hemodynamic response that could be obtained by each noninvasive VV selection method was extrapolated from the curve of LV dP/dt max versus VV. The study included 25 patients (80% men, age 66 +/- 9 years, 44% ischemic). The maximum achievable LV dP/dt during biventricular pacing was obtained by a median left ventricular preactivation of 30 ms and increased the baseline unpaced LV dP/dt from 774 +/- 181 to 934 +/- 179 mm Hg/s (p <0.001). The noninvasive optimization method selected the VV leading to the narrowest QRS measured from the earliest deflection and obtained the smallest difference with regard to the maximum achievable LV dP/dt. Furthermore, of all the VV optimization methods tested, this was the only 1 that significantly improved on the hemodynamic response obtained by programming a predefined VV of 0 ms in all patients (925 +/- 178 vs 906 +/- 183 mm Hg/s; p = 0.003). In conclusion, achieving the narrowest QRS measured from the earliest deflection obtained a better acute hemodynamic response than the other VV optimization methods. It also improved the response obtained by default simultaneous biventricular pacing, although this improvement was limited in magnitude.

Cardiac resynchronization therapy in patients with ischemic versus non-ischemic heart failure: Differential effect of optimizing interventricular pacing interval

Whether sequential biventricular pacing provides substantial benefits over conventional simultaneous stimulation remains unclear, particularly regarding the differences between ischemic and non-ischemic patients. The purpose of this study was to evaluate the acute effect of interventricular pacing interval (V-V) optimization on left ventricular (LV) systolic performance and dyssynchrony in ischemic versus non-ischemic patients. Sixty-nine consecutive patients underwent cardiac resynchronization therapy. Within 3 days after implantation, V-V was optimized by measuring (every 20-millisecond interval) LV systolic performance (LV outflow-tract velocity-time-integral, LVOT VTI) and LV dyssynchrony (using tissue Doppler imaging). Optimal pacing configuration was the one achieving maximal increase in LVOT VTI. Optimized sequential pacing provided a significant improvement in LVOT VTI compared to simultaneous stimulation (from 138 +/- 42 to 163 +/- 38 mm, P < .001) and was associated with a significant reduction in LV dyssynchrony (from 33 +/- 31 to 19 +/- 24 milliseconds, P < .001). The increase in LVOT VTI and LV ejection fraction after implantation was greater in non-ischemic as compared to ischemic patients (P < .001). However, V-V optimization yielded a larger improvement in LV systolic performance in ischemic patients (P = .03). Consequently, the 2 groups showed comparable response after V-V optimization. A significant correlation was observed between LV scar tissue and optimal V-V interval (r = 0.58, P < .001), with a larger extent of scar related to a larger level of LV preactivation, probably reflecting slow intra-LV conduction. Optimized sequential biventricular pacing further increased LV systolic performance as compared to simultaneous stimulation, particularly in ischemic patients where the presence of a large scar was correlated with a larger LV preactivation.

Effects of cardiac resynchronization therapy on coronary blood flow: Evaluation by transthoracic Doppler echocardiography☆

Relatively limited and conflicting data are available on the effects of cardiac resynchronization therapy (CRT) on coronary blood flow (CBF). To investigate changes in the left anterior descending coronary artery (LAD) flow under different CRT pacing modes by means of transthoracic Doppler echocardiography (TTE). Twenty-two responders to CRT (67+/-11 years) with idiopathic dilated cardiomyopathy underwent TTE assessment of LAD flow and Tissue Velocity Imaging during 4 programming modes: intrinsic conduction (IC), right ventricular pacing (RV), simultaneous biventricular pacing (BVP), BVP with left ventricular (LV) pre-activation. Mean coronary flow velocity (CFV) was increased by simultaneous BVP (p=0.0063 vs. IC) and BVP with LV pre-activation (p<0.0001 vs. IC; p=0.027 vs. simultaneous BVP). Peak CFV and LAD flow velocity/time integral were highest during BVP with LV pre-activation. A reduction in septal-to-lateral delay and an increase in peak systolic velocity in the basal septum were observed during simultaneous BVP and BVP with LV pre-activation. In CRT responders with idiopathic dilated cardiomyopathy, an increase in LAD flow, assessed by TTE, was observed during simultaneous BVP and BVP with LV pre-activation. This was associated with an improvement in regional myocardial contraction and a decrease in intraventricular dyssynchrony.

Optimizing the Programation of Cardiac Resynchronization Therapy Devices in Patients With Heart Failure and Left Bundle Branch Block

This study was conducted to investigate the clinical impact of cardiac resynchronization device optimization. A series of 100 consecutive patients received cardiac resynchronization therapy. In the first 49 patients, an empirical atrioventricular delay of 120 ms was set, with simultaneous biventricular stimulation (interventricular [VV] interval=0 ms). In the next 51 patients, systematic atrioventricular optimization was performed. VV optimization was also performed, selecting 1 VV delay: right or left ventricular preactivation (+30 or -30 ms) or simultaneous (VV interval=0 ms), according to the best synchrony obtained by tissue Doppler-derived wall displacement. At follow-up, patients who were alive without cardiac transplantation and showed improvement of >or=10% in the distance walked in the 6-minute walking test were considered responders. There were no differences between the 2 groups at baseline. Left ventricular ejection fraction improved in the 2 groups, but left ventricular cardiac output improved only in the optimized group. At 6 months, patients with optimized devices walked slightly further in the 6-minute walking test (497+/-167 vs 393+/-123 m, p<0.01), with no differences in New York Heart Association functional class or quality of life compared with nonoptimized patients. Overall, the number of nonresponders were similar in the 2 groups (27% vs 23%, p=NS). In conclusion, the echocardiographic optimization of cardiac resynchronization devices provided a slight incremental clinical benefit at midterm follow-up. Simple and rapid methods to routinely optimize the devices are warranted.

Cardiac Resynchronization Therapy: Variations in Echo‐Guided Optimized Atrioventricular and Interventricular Delays During Follow‐Up

Relatively few data are available on long-term echocardiographic optimization of atrioventricular (AV) and interventricular (VV) delay programming in cardiac resynchronization therapy (CRT). We assessed variations in optimized AV and VV delays during long-term follow-up. Thirty-seven consecutive heart failure patients received Doppler echocardiographic optimization of AV and VV delay within 48 hours from CRT device implantation, at 6 months and at 12 months (the last for the first enrolled 14 patients). After implantation, median optimized AV delay was 100 ms (range, 45 ms); VV optimization led to simultaneous biventricular activation in 4 patients, left ventricular preactivation in 17 patients and right ventricular preactivation in 16 patients. At 12 months median AV delay decreased to 85 ms (23 ms) (P < 0.05 vs. baseline). With respect to previous assessment, VV delay variations > or =40 ms were observed in 41% of the patients at 6 months and in 57% of the tested patients at 12 months. A nonconcordance (by Kappa test) of optimized VV delays was found between each new assessment and the previous one. VV delay optimization was associated with significant (P < 0.001) increases in aortic velocity time integral both at baseline and during follow-up. Echocardiographic optimization of AV and VV delay is associated with broad intraindividual variability during follow-up. A new assessment of optimized VV delays during long-term follow-up reveals a nonconcordance with previous values and provides increases in forward stroke volume.

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 resynchronization predicted by individual performance of right and left univentricular pacing: A study on the impact of sequential biventricular pacing on ventricular dyssynchrony

There is increasing evidence that improvement in left ventricular (LV) mechanical dyssynchrony is correlated with LV functional recovery in patients undergoing cardiac resynchronization therapy (CRT). Recent studies have suggested that sequential biventricular pacing may be important for further optimizing parameters of ventricular dyssynchrony. The purpose of this study was to evaluate the acute effect of varying sequential biventricular pacing settings on echocardiographic parameters of ventricular dyssynchrony and to identify predictors of the optimal setting. Twenty-nine patients referred for CRT were evaluated with standard echocardiography and tissue Doppler imaging before and after implantation. Indices of interventricular and intraventricular dyssynchrony were assessed for trends during simultaneous and sequential biventricular pacing. Twelve patients (41%) demonstrated linear trends of decreasing systolic dyssynchrony index with increasing LV preactivation. The mean additional decrease in dyssynchrony index at the optimized setting compared with simultaneous biventricular pacing was 26% (P <.04). Twenty-two patients (76%) demonstrated linear trends to decreasing interventricular dyssynchrony with increasing LV preactivation. The trends were strongly correlated with the magnitude of difference of the respective dyssynchrony measures in right ventricular only and LV only univentricular pacing. A significantly, superior capacity of LV only pacing for ventricular resynchronization was found in this subgroup of patients. In patients undergoing CRT, differences in the performance of univentricular pacing are associated with linear trends in ventricular dyssynchrony parameters in sequential biventricular pacing. Quantitative differences in LV univentricular pacing impact on the capacity of biventricular pacing to correct ventricular dyssynchrony.

Anodal Capture in Cardiac Resynchronization Therapy Implications for Device Programming

Right ventricular (RV) anodal capture (AC) has been reported in cardiac resynchronization therapy (CRT), when left ventricular (LV) pacing uses pseudobipolar (LV tip to RV proximal electrode) configuration. The aim of the study was to analyze the prevalence of AC and its implications for device programming. When AC occurred, the resulting QRS morphology was evaluated with the following pacing modes: (1) LV tip pacing plus RV AC, (2) Biventricular (BiV) pacing (i.e., both LV and RV tip pacing), and (3) BiV pacing plus RV AC. Several interventricular pacing (VV) intervals from 50 ms of LV preactivation to 30 ms of RV preactivation were tested in modes 2 and 3. From 38 consecutive patients, AC was achieved in 14 (in 74% of the pacemakers and in none of the defibrillators). LV tip pacing plus RV AC obtained narrower QRS than BiV pacing at all VV intervals in seven of the patients with AC (50%). When BiV pacing is combined with RV AC, it produced a ventricular depolarization through two wave fronts (one from the LV tip and the second from either the ring or the tip of the RV lead depending on the VV interval programmed). AC obtained the narrowest QRS of all tested pacing modes in a significant proportion of patients undergoing CRT. Though the stimulus was delivered from three sites (BiV pacing plus RV AC mode), only two wave fronts of ventricular activation were seen by ECG.

Invasive Optimization of Cardiac Resynchronization Therapy: Role of Sequential Biventricular and Left Ventricular Pacing

Aim of this invasive study was to characterize and quantify changes in left ventricular (LV) systolic function due to sequential biventricular pacing (BV) as compared to right atrial triggered simultaneous BV (BV(0)), LV, and right ventricular (RV) pacing in patients with congestive heart failure (CHF). In 22 CHF patients, all in sinus rhythm, temporary multisite pacing was performed prior to implantation of a permanent system. LV systolic function was evaluated invasively by the maximum rate of LV pressure increase (dP/dt(max)). Sequential BV pacing was performed with preactivation of either ventricle at 20-80 ms. In comparison to RV pacing, LV and BV(0) pacing increased dP/dt(max) by 33.9 +/- 19.3% and 34.0 +/- 22.6%, respectively (P < 0.001). In 9 patients, optimized sequential BV pacing further improved dP/dt(max) by 8.5 +/- 4.8% compared to BV(0) (range 3.3-17.1, P < 0.05). In 10 patients exhibiting a PR interval < or =200 ms, LV pacing was either superior (n = 6) or equal to BV(0) pacing (n = 4). In these 10 patients, LV pacing yielded a 7.4 +/- 8.0% higher dP/dt(max) than BV(0) pacing (P < 0.05). Using sequential BV pacing, generally with LV preactivation, moderate improvements in LV systolic function can be achieved in selected patients. Baseline PR interval may aid in the selection of the optimum cardiac resynchronization therapy (CRT) mode, favoring LV pacing in patients with a PR interval < or =200 ms.

Echocardiographic Examination of Atrioventricular and Interventricular Delay Optimization in Cardiac Resynchronization Therapy

In 21 patients implanted with a biventricular pacing device with programmable interventricular delay (VVd), the myocardial performance index (MPI) was evaluated during spontaneous sinus rhythm, simultaneous biventricular pacing, and sequential biventricular pacing at different VVds and atrioventricular delays (AVds). The AVd-VVd combination associated with the minimum MPI defined patient-tailored biventricular pacing. Simultaneous biventricular pacing significantly improved MPI compared with spontaneous sinus rhythm. An additional improvement was obtained by tailored biventricular pacing. The optimal AVds were significantly shorter during right ventricular preactivation than during left ventricular preactivation.