VV Delay Research Articles

Programmed versus Effective VV Delay during CRT Optimization: When What You See Is Not What You Get

In cardiac resynchronization therapy (CRT) devices, the interventricular (VV) delay denotes the time interval between left (LV) and right ventricular (RV) pacing. This study aimed to determine the proportion of patients in whom the effective VV delay (VVeff , delay between LV and RV depolarization, being induced either by pacing or intrinsic conduction) is different from the programmed VV delay during a standard VV delay optimization procedure. Thirty-three patients with heart failure and left bundle branch block configuration without total atrioventricular (AV) block receiving CRT were prospectively included. VVeff was calculated from intrinsic AV intervals, programmed optimal AV delay, and programming system. Intrinsic AV intervals were measured on intracardiac electrograms. The optimal AV and VV delays were determined by highest increase in maximum rate of LV pressure rise (dP/dtmax ). VV delays of 20-80 ms LV and RV preactivation were tested. Calculated maximum possible VVeff was shorter than 80 ms LV preactivation in up to 46% of patients and shorter than 40 ms LV preactivation in up to 3% of the patients. These proportions were 6% and 0% during 80 and 40 ms RV preactivation, respectively. In CRT patients with left bundle branch block without total AV block, the effective VV delay is shorter than the programmed VV delay during a standard optimization procedure in approximately half of the patients and this phenomenon is encountered predominantly during LV preactivation by 40 ms or more. Calculation of the individual maximum VVeff in advance can shorten the VV delay optimization procedure.

76 COMPARISON OF THE USE OF CENTRAL AND PERIPHERAL PRESSURE WAVEFORMS FOR OPTIMIZATION OF CARDIAC RESYNCHONIZATION THERAPY

Background: In patients with cardiac dyssynchrony, optimization of cardiac resynchronization therapy (CRT) is achieved by ascertaining the atrial-ventricular (AV) and inter-ventricular (VV) delays that give maximum cardiac output (CO). As continuous CO measurements are not readily available, this study assesses the use of the peripheral (radial) and central aortic pressure waveform for optimal AV and VV delay using a haemodynamic model. Methods: The model consisted of left and right heart chambers simulated by time varying elastance (variable capacitors), systemic and pulmonary sections simulated by windkessel segments (resistance, capacitance) and a delay line for the arm. Model parameters were altered to obtain maximal values (optimization criterion) for central and peripheral systolic, diastolic and pulse pressure (cSBP, cDBP, cPP, pSBP, pDBP, pPP) and CO from baseline settings of AV (120 ms) and VV (0 ms) delays. Results: The optimal AV delay was not different for all hemodynamic measures. However, optimal VV delay was significantly different for blood pressure parameters compared to CO (*p<0.001).Conclusions: The study indicates that both peripheral and central pressure parameters give similar results for CRT optimisation for AV and VV delay. However optimization for pressure parameters gives significant differences for VV delay compared to CO. This suggests that the ventricular -vascular coupling is an important parameter to be considered for CRT optimisation.

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.

007 Should current modalities of VV optimisation be trusted? An assessment of the internal validity of echocardiographic, electrocardiographic and haemodynamic modalities of optimisation: Abstract 007 Figure 1

Background In atrial fibrillation (AF), VV optimisation of biventricular pacemakers can be examined in isolation. We used this approach to evaluate the internal validity of three VV optimisation methods. Methods 20 patients (16 men, age 75±7) in AF were optimised, at two paced heart rates, by LVOT VTI (flow), non-invasive arterial pressure, and ECG (minimising QRS duration). Each optimisation method was evaluated by: singularity (unique peak of function), reproducibility of optimum, and biological plausibility of the distribution of optima. Results The reproducibility (SD of the difference, SDD) of the optimal VV delay is 10 ms for pressure, vs 8 ms (p=NS) for QRS and 34 ms (p 2 =10.9, p Conclusions Using non-invasive arterial pressure, VV delay optimisation is achievable with good precision, satisfying all 3 criteria of internal validity, and the optimum is unaffected by heart rate. Neither QRS minimisation nor LVOT VTI satisfy all validity criteria and are therefore weaker candidate modalities for VV optimisation.

Comparison of quick optimization of interventricular delay between simple methods: intracardiac electrogram and surface electrocardiogram after cardiac resynchronization therapy

It is time consuming to obtain optimal interventricular (VV) delay by conventional methods. This study is designed to compare quick optimization between intracardiac electrogram (IEGM) with surface electrocardiogram (ECG)-guided VV delay optimization for cardiac resynchronization therapy (CRT). Fifty-one heart failure patients (M/F = 34/17, age = 71 ± 10-year-old) scheduled for CRT implantation were included. After atrioventricular optimization, VV delay optimization was performed by either the IEGM or surface ECG method. Aortic velocity time integral (AVTI) was used as a reference in comparing these two methods. Real-time three-dimensional echocardiography was studied under three varying parameters-CRT switched off or CRT switched on, and VV delay optimized by IEGM guided or surface ECG. The AVTI could be improved equally by either IEGM-guided or surface ECG-guided VV optimization. All the other parameters [QRS width, systolic dyssynchrony index (SDI), left ventricular ejection fraction (LVEF), left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV)] could be improved by either the IEGM or ECG method in these patients. In the multivariate logistic regression analysis, the immediate improvement of acute LVEF was independently related to favourable outcomes (odds ratio 1.23, 95% CI = 1.03-1.47, P = 0.02). The AVTI, QRS width, SDI, LVEF, LVEDV, and LVESV could be improved equally by either IEGM-guided or surface ECG-guided method after CRT.

A systematic approach to designing reliable VV optimization methodology: Assessment of internal validity of echocardiographic, electrocardiographic and haemodynamic optimization of cardiac resynchronization therapy

BackgroundIn atrial fibrillation (AF), VV optimization of biventricular pacemakers can be examined in isolation. We used this approach to evaluate internal validity of three VV optimization methods by three criteria. Methods and resultsTwenty patients (16 men, age 75±7) in AF were optimized, at two paced heart rates, by LVOT VTI (flow), non-invasive arterial pressure, and ECG (minimizing QRS duration). Each optimization method was evaluated for: singularity (unique peak of function), reproducibility of optimum, and biological plausibility of the distribution of optima.The reproducibility (standard deviation of the difference, SDD) of the optimal VV delay was 10ms for pressure, versus 8ms (p=ns) for QRS and 34ms (p<0.01) for flow.Singularity of optimum was 85% for pressure, 63% for ECG and 45% for flow (Chi2=10.9, p<0.005).The distribution of pressure optima was biologically plausible, with 80% LV pre-excited (p=0.007). The distributions of ECG (55% LV pre-excitation) and flow (45% LV pre-excitation) optima were no different to random (p=ns).The pressure-derived optimal VV delay is unaffected by the paced rate: SDD between slow and fast heart rate is 9ms, no different from the reproducibility SDD at both heart rates. ConclusionsUsing non-invasive arterial pressure, VV delay optimization by parabolic fitting is achievable with good precision, satisfying all 3 criteria of internal validity. VV optimum is unaffected by heart rate. Neither QRS minimization nor LVOT VTI satisfy all validity criteria, and therefore seem weaker candidate modalities for VV optimization. AF, unlinking interventricular from atrioventricular delay, uniquely exposes resynchronization concepts to experimental scrutiny.

A Study of Mechanical Optimization Strategy for Cardiac Resynchronization Therapy Based on an Electromechanical Model

An optimal electrode position and interventricular (VV) delay in cardiac resynchronization therapy (CRT) improves its success. However, the precise quantification of cardiac dyssynchrony and magnitude of resynchronization achieved by biventricular (BiV) pacing therapy with mechanical optimization strategies based on computational models remain scant. The maximum circumferential uniformity ratio estimate (CURE) was used here as mechanical optimization index, which was automatically computed for 6 different electrode positions based on a three-dimensional electromechanical canine model of heart failure (HF) caused by complete left bundle branch block (CLBBB). VV delay timing was adjusted accordingly. The heart excitation propagation was simulated with a monodomain model. The quantification of mechanical intra- and interventricular asynchrony was then investigated with eight-node isoparametric element method. The results showed that (i) the optimal pacing location from maximal CURE of 0.8516 was found at the left ventricle (LV) lateral wall near the equator site with a VV delay of 60 ms, in accordance with current clinical studies, (ii) compared with electrical optimization strategy of E RMS, the LV synchronous contraction and the hemodynamics improved more with mechanical optimization strategy. Therefore, measures of mechanical dyssynchrony improve the sensitivity and specificity of predicting responders more. The model was subject to validation in future clinical studies.

Optimization of Cardiac Resynchronization Therapy: Importance of Programmed Parameters

One of the basic tenets of cardiac resynchronization therapy (CRT) is that optimization of programmed parameters is important to maximize the therapeutic response. Both atrioventricular (AV) and interventricular (VV) timing intervals have been suggested as potential methods to improve response rates. A variety of techniques have been described to determine the optimal AV and VV delays. Many of these methods have demonstrated acute hemodynamic benefits; however, multicenter data proving long-term clinical benefit have been lacking. Echocardiography-guided methods have been most commonly employed, but no technique has been shown to be superior. In fact, many of these techniques have poor reproducibility and are time-consuming. Device-based algorithms allow for a rapid, simplified approach to CRT optimization; however, their clinical value has also been called into question. This review will describe the different techniques for CRT optimization and evaluate their potential value and limitations.

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.

The advanced experience in combining Biv-pacing with AVN-first for improving efficiency from CRT

Background and objectivesCardiac resynchronisation therapy (CRT) is now an established non-pharmacologic therapy for advanced congestive heart failure (CHF) with electromechanical delay. However, lack of a favourable response in about 1/3...

Echocardiography versus intracardiac electrocardiography-based optimization for cardiac resynchronization therapy

Optimization of AV and VV delay programming has been shown to be essential for the success of cardiac resynchronization therapy (CRT). Acute hemodynamic improvement can be obtained by intracardiac electrocardiogram (IEGM)-based optimization. The aim of the present study was to evaluate whether this IEGM-based algorithm is comparable to the current gold standard of echocardiography. After device implantation patients with standard criteria for CRT, AV and VV delay programming was either optimized by an IEGM-based algorithm (IEGM group, n = 24) or by echocardiography (echo group, n = 24). Cardiopulmonary exercise capacity was assessed after 3 and 12months on the basis of NYHA class and the 6-min-walk test. Left ventricular ejection fraction was evaluated by echocardiography. In both groups there was a significant decrease in NYHA class and a significant increase in 6-min-walk distance and ejection fraction after 3 and 12months. After 12months there was no significant difference in the proportion of responders, NYHA class and 6-min-walk distance between the IEGM the echo group. The present data show that a sustained improvement of cardiopulmonary exercise capacity can be obtained by optimizing CRT patients on the basis of an IEGM algorithm. The comparable results for cardiopulmonary exercise parameters suggest that this new method might become an important tool for adjusting CRT programming in daily practice.

Cardiac Resynchronization Therapy Optimization Using Noninvasive Cardiac Output Measurement

Noninvasive cardiac output (CO) measurement (NICOM) is a novel method to assess ventricular function and offers a potential alternative for optimization of cardiac resynchronization therapy (CRT) devices. We compared the effect of NICOM-based optimization to no optimization (empiric settings) on CRT outcomes. Two hundred and three patients undergoing CRT were assessed in two consecutive nonrandomized groups; an empiric group (n = 54) was programmed to "out of the box" settings with a fixed AV delay of 120 ms and a VV delay of 0 ms; and the optimization group (n = 149) underwent adjustments of both the AV and VV delays according to the greatest improvement in resting CO. The primary endpoints were improvements in left ventricular (LV) volumes and function from baseline at 6 months. Secondary endpoints were change in New York Heart Association (NYHA) class, quality of life score, and 6-minute walk test (6 MWT) performance. After 6 months of CRT, the optimization group had a better clinical response with lower NYHA class (2.1 ± 0.8 vs 2.4 ± 0.8, P = 0.048) and quality of life scores (35 ± 18 vs 42 ± 20, P = 0.045) but no differences in 6-MWT performance (269 ± 110 vs 277 ± 114 m, P = 0.81). Echocardiographic response was also better in the optimization group with lower LV end systolic volume (108 ± 51 vs 126 ± 60 mL, P = 0.048) and higher ejection fraction (30 ± 7 vs 27 ± 8, P = 0.01) compared to empiric settings. Device optimization using noninvasive measures of CO is associated with better clinical and echocardiographic response compared to empiric settings.

86 How often is important adjustment of pacing intervals required for optimal response following CRT?

Introduction A significant minority of patients do not experience clinical benefit following cardiac resynchronisation therapy (CRT). Haemodynamically-guided adjustment of the intervals between chambers paced (“optimisation” of atrio-ventricular (AV) and left-right ventricular (VV) delays) may be undertaken to improve the chance of response to CRT. However, data to support this approach as standard management are lacking and many institutions programme CRT devices to deliver “out-of-the-box” intervals, only undertaking optimisation when clinical response is lacking. We sought to determine how often the “out-of-the-box” settings are optimal or acceptable and how often CRT optimisation results in significant alteration of the pre-programmed pacing intervals. Methods Data were collected from 180 consecutive patients who underwent CRT followed by optimisation within 24 h. Optimisation was performed with serial adjustment of AV and VV intervals. Haemodynamic assessment was undertaken using either echocardiography or Non-Invasive Cardiac Output Measurement. The optimal pacing intervals were considered to be those which resulted in greatest acute augmentation of cardiac output and the device was programmed accordingly. The final settings were compared with the pre-programmed settings for that device and the difference (AV or VV Adjustment) derived, taking into account the preset paced or sensed AV delay. An AV or VV Adjustment of more than 40 ms was considered to be clinically significant. Data are presented as mean (SD). Results Optimal AV delay ranged from 60 to 200 ms (mean 124 ms (30)), VV delay ranged from 0 to 100 ms (mean 23 ms (19)). With the pre-set pacing parameters, cardiac output was acutely augmented by 13.1 (34)%. Optimised CRT produced further improvement of cardiac output, to 24.9 (32)% augmentation. “Out-of-the-box” settings were found to be optimal in 11 (6.1%), or requiring only minor alteration in 120 (66.7%). A clinically significant alteration in AV delay was made in 40 (22.2%), in VV delay in 12 (6.7%) or in either parameter in 49 (27.2%). Conclusions Significant adjustment of AV or VV delay is required in over a quarter of patients receiving CRT. Optimisation of pacing intervals provides augmentation of cardiac output over and above the “out-of-the-box” settings. The findings suggest that optimisation is an important component of resynchronisation therapy.

87 Optimisation of VV delay of CRT is more reproducible using peak velocities than using velocity time integral, as well as being quicker

<h3>Background</h3> It is not obvious which is a better echocardiographic marker for optimisation of AV or VV delay: stroke distance (VTI) or peak velocity. The biggest problem is genuine physiological variability between beats. Because optimisation of VV delay requires detection of persistent changes in cardiac function (“signal”), which may be small in relation to beat-to-beat variability (“noise”), we should choose measurements with the best signal-to-noise ratio and reproducibility. The standard echocardiographic method of choice for VV delay optimisation is to maximise left ventricular outflow tract velocity time integral (LVOT VTI). An alternative is peak velocity instead of VTI as the parameter to be measured. But surely VTI, which is encompassing and cumulating more data, is more immune to disruption by spontaneous variability between beats, and therefore simply using peak velocity might give a less reliable optimum? Surely the time saved by using peak would have a price to pay in poorer reproducibility of the optimum? In this study, we evaluate whether peak velocity is a suitable alternative to VTI, having regard to both time consumed and reproducibility. We also examine whether averaging multiple replicate measurements improves optimisation. <h3>Methods &amp; Results</h3> VV optimisation was performed on 40 subjects with biventricular pacemakers using LVOT velocity (VTI or peak) as the echocardiographic marker being maximised. Importantly, 6 successive replicate optimisations were performed per patient at a single session. Scatter of apparent VV optimum between repeat optimisations was threefold smaller for peak than VTI (p&lt;0.03), with a single measurement for each. Peak velocity had a higher intraclass correlation coefficient (ICC) than VTI (0.66 vs 0.53, p=0.003). Scatter between replicate optimisations is reduced if, instead of single measurements, we use pairs, or triplicates (ANOVA p&lt;0.0001). This benefit occurs with both peak and VTI (p&lt;0.001 among each). Time taken for acquisition and analysis of a single optimisation (6 settings) was 17.5 s for peak and 57.5 s for VTI (p&lt;0.0001). <h3>Conclusions</h3> Doppler optimisation of VV delay using peak velocity rather than VTI is (as expected) quicker but (surprisingly) more accurate. Making replicate measurements further improves reproducibility. Perhaps guidelines should favour peak over VTI and mandate multi-replicate averaging? These data suggest a rare opportunity to reduce labour while increasing reliability of optimisation. Indeed, triplicate peak velocity assessment takes the same amount of time as a single VTI, and identifies the VV optimum 3 times more confidently. While VTI measurement remains essential for assessing stroke volume and cardiac output, for optimisation purposes it comparison of peak velocity between different settings is both faster and more reliable.

116 CRT optimisation: improving echocardiographic techniques by accommodating biological variability within different echocardiographic parameters

<h3>Background</h3> In optimisation of CRT (and even selection for implantation) we may have underestimated the impact of beat-to-beat variation on echocardiographic measurements. This can be quantified most clearly in the optimisation process, in which genuine small changes in cardiac function (signal) must be detected among potentially large beat-to-beat variation (noise). <h3>Methods and Results</h3> In this large study of biological variability, we performed over 2000 echocardigraphic measurements in 12 patients. We performed separate, replicate measurements at a series of interventricular delays of each potential optimisation modality at rest. This included (i) 3D systolic dyssynchrony index, (ii) aortic pre-ejection time, (iii) interventricular mechanical delay, (iv) LVOT VTI and (v) QRS width. The equivalent of 31 optimisations per patient were performed. For single measurements at each setting, agreement between successive optimisations was low, at 39% for SDI, 41% for aortic pre-ejection time, 32% for IVMD, 54% for LVOT VTI and 58% for QRS width. Agreement between one method and another, using single replicates, was similarly low, with the average agreement between optima by two methods being only 18% similar to pure guesswork. The intraclass correlation coefficient was low for all methods at 0.11, 0.51, 0.30, 0.50 and 0.55 respectively. The intraclass correlation coefficients improved to 0.19, 0.63, 0.42, 0.54 and 0.66 (p=0.001) when averages of paired measurements were used. To optimise within 20 ms or 10 ms of the true optimum, requires a greater number of measurements, as seen in Abstract 116 figure 1, dependant on the intraclass correlation coefficient. The scatter of optima obtained reduced (improved) significantly when using averaged pairs of measurements compared to single measurements from 23 ms to 18 ms (3D SDI), 14 ms to 10 ms (aortic pre-ejection time), 28 ms to 22 ms (IVMD), 21 ms to 16 ms (LVOT VTI) and 14 ms to 10 ms QRS duration (p=0.0002). <h3>Conclusions</h3> Because of beat-to-beat variability, VV delay optimisation by any of the echocardiographic techniques is not realistic unless multiple replicates are performed and averaged. Smoothing biological variation by averaging multiple measurements allows the full potential of echocardiographic optimisation to be achieved and improves the consistency of optimisation. Trying to save time by performing inadequate numbers of replicates is a false economy and leads to optimisation being a form of randomisation. These observations may also cast light on to why attempts to identify future responders from CRT has not – when tested in externally monitored randomised trials—been fruitful: dyssynchrony assessment to select patients for implantation may need averaging too, and of far more replicate measurements than is current practice. Integration of this biological insight into technological achievements of clinical imaging is necessary, if reliable predictors of which patients will benefit from CRT, are to be developed.

Relationship between intracardiac impedance and left ventricular contractility in patients undergoing cardiac resynchronization therapy

AimsCardiac resynchronization therapy (CRT) has dramatically improved the symptoms and prognosis of patients with heart failure in large randomized clinical trials. Optimization of device settings may maximize benefit on an individual basis, although the best method for this is not yet established. We evaluated the use of cardiogenic impedance measurements (derived from intracardiac impedance signals) in CRT device optimization, using invasive left ventricular (LV) dP/dtmax as the reference.Methods and resultsSeventeen patients underwent invasive haemodynamic assessment using a pressure wire placed in the LV cavity at the time of CRT device implantation. Intracardiac impedance measurements were made at different atrioventricular (AV) and interventricular (VV) delays and compared with LV dP/dtmax. We assessed the performance of patient-specific and generic impedance-based models in predicting acute haemodynamic response to CRT. In two patients, LV catheterization with the pressure wire was unsuccessful and in two patients LV lead delivery was unsuccessful; therefore, data were acquired for 13 out of 17 patients. Left ventricular dP/dtmax was 919 ± 182 mmHg/s at baseline and this increased acutely (by 24%) to 1121 ± 226 mmHg/s as a result of CRT. The patient-specific impedance-based model correctly predicted the optimal haemodynamic response (to within 5% points) for AV and VV delays in 90 and 92% of patients, respectively.ConclusionCardiogenic impedance measurements are capable of correctly identifying the maximum achievable LV dP/dtmax as measured by invasive haemodynamic assessment. This study suggests that cardiogenic impedance can potentially be used for CRT optimization and may have a role in ambulatory assessment of haemodynamics.

Electrogram-Based Optimal Atrioventricular and Interventricular Delays of Cardiac Resynchronization Change Individually During Exercise

Background Limited data suggest that optimal atrioventricular (AV) and interventricular (VV) delays are different at rest than during exercise in patients with heart failure. We assessed the feasibility and reproducibility of an electrogram-based method of optimization called QuickOpt at rest and during exercise. Methods Patients with a St Jude Medical cardiac resynchronization therapy implantable cardioverter-defibrillator were subjected to a graded treadmill test, and QuickOpt was repeatedly measured prior to, during, and after the exercise. Results Twenty-four patients (16 males, aged 67.4 ± 7.7 years) participated. At rest, delays (in ms) were 110.4 ± 20.1 for sensed AV delay and –70 (LV pacing first) to +20 (RV pacing first) for VV delay. The changes in QuickOpt-derived delays at rest were not significant despite change in body position. During exercise, QuickOpt-derived AV delays did not change in 11 patients, were shorter during peak exercise in 8 patients, and were longer in 3 patients (average value during peak exercise was 126.5 ± 15.8 ms, P = 0.04 compared to baseline). The QuickOpt-derived VV delay gradually shifted toward earlier right ventricular pacing during exercise in 19 patients, while no changes were seen in 3 patients, and a shift occurred toward earlier left ventricular pacing in 2 patients (average value during peak exercise was –30.7 ± 22.2; P = 0.001 compared to baseline). There was no correlation between changes in the QuickOpt-derived AV and VV delays and heart rate. Conclusions The application of electrogram-based algorithm is feasible both at rest and during exercise. The results are reproducible. QuickOpt-derived AV and VV delays individually change during exercise.

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.

Impact of VV optimization in relation to left ventricular lead position: an acute haemodynamic study

Left ventricular (LV) lead placement to the most delayed segment offers the greatest potential benefit to cardiac resynchronization therapy (CRT). We assessed the impact of interventricular (VV) optimization on acute changes in cardiac output (CO) in patients with and without LV pacing of the most delayed segment. In 124 patients, the most delayed segment was defined by speckle tracking radial strain and the LV lead position by biplane fluoroscopy. Patients were classified as either a concordant (LV lead at latest site), adjacent (within one segment), or remote (two or more segments away) LV lead. Atrioventricular (AV) and VV delays were optimized by echocardiography. Cardiac output was measured non-invasively and a >20% increase in CO from baseline (intrinsic) defined acute response. Changes in CO in patients with concordant, adjacent, or remote LV leads were recorded following atrioventricular optimization alone (AV OPT) and after combined AV and VV optimization (AV/VV OPT). Compared with AV OPT pacing, AV/VV OPT produced a greater rise in CO (5.45 ± 1.1 vs. 5.76 ± 1.2 L/min, P< 0.001) and higher acute response rates (48.4 vs. 61.3%, P= 0.041). In adjacent patients, compared with AV OPT pacing, AV/VV OPT settings increased the response rate from 36.4 to 63.6% (P= 0.037). VV optimization had no effect on acute response rates in patients with remote (26.7 vs. 33.3%, P = 0.581) or concordant LV leads (65.6 vs. 72.1%, P = 0.438). VV optimization overcomes some but not all of the deleterious effects of a suboptimal LV lead position.

A Case of Refractory Heart Failure Successfully Managed by Optimization of the Intra-Cardiac Conduction Delays Using Smart Delay

Background: Optimal atrial-ventricular (AV) and intra-ventricular (VV) conduction delay setting is mandatory for maintaining left ventricular pump function in patients who have undergone cardiac resynchronization therapy (CRT). Echocardiography is considered the gold standard of timing optimization but is a time-consuming procedure.Purpose: We report an interesting case of refractory heart failure who were successfully managed by algorithmic AV and VV delay programming using Smart Delay algorithm.Case: A 54-year-old female patient. The patient was diagnosed as NYHA III degree heart failure in September 2008, CRT-D was implanted in October 2008. In late December 2009, the patient was diagnosed as NYHA IV degree heart failure, and the patient was transferred to our hospital for the treatment of arrhythmias and heart failure.Therapy: optimization of the intra-cardiac conduction delays was achieved using Smart Delay algorithm (paced AV 160 to 180 msec, sensed AV 160 to 180 msec, and BIV pacing to LV pacing), which resulted in a prompt increase in her stroke volume from 46 to 80 ml with consequent improvement in heart failure symptoms.Conclusion: We experienced a case of refractory heart failure successfully managed by optimization of the intra-cardiac conduction delays using Smart Delay.