Real-time 3D echo in patient selection for cardiac resynchronization therapy

Real-time three-dimensional echocardiography for detection of cardiac sarcoidosis in the early stage: a cross-sectional single-centre study

BACKGROUND

Sarcoidosis with cardiac involvement has a relatively high morbidity and mortality, and early diagnose of cardiac sarcoidosis is a critical issue. Systolic dyssynchrony index (SDI) measured by three-dimensional echocardiography was used in our study for detection of subclinical left ventricular (LV) systolic dysfunction in patients with sarcoidosis and normal LV function on two-dimensional echocardiography.

METHODS

Forty-four patients diagnosed with sarcoidosis (without clinically apparent cardiac involvement) and 44 healthy control subjects were included in this study. Two-dimensional echocardiographic parameters, also LV volumes and SDI measured by 3D echocardiography were analyzed in all participants.

RESULTS

While two-dimensional echocardiographic results of both study groups were similar; SDI_16 (SDI for 16 segments of LV) results were significantly higher in sarcoidosis group compared to healthy controls (6.99 ±5.02 vs 2.89 ± 1.32, p < 0.0001).

CONCLUSION

SDI_16 was higher in patients with sarcoidosis compared to healthy controls probably due to patchy infiltration characteristic of the disease. This parameter could be used as a marker to identify patients with cardiac involvement of sarcoidosis in the early phase.

Left ventricular systolic dyssynchrony in patients with Kawasaki disease: a real-time three-dimensional echocardiography study

The left ventricular (LV) systolic dyssynchrony index (SDI) is an important prognostic indicator for many cardiovascular diseases; however, the characteristics of the SDI in patients with Kawasaki disease (KD) are unknown. In this study, we aimed to identify and quantify the SDI using real-time three-dimensional echocardiography (RT3DE) in KD patients during different phases. In addition, we intended to explore whether the SDI is associated with systolic dysfunction. Seventy consecutive KD patients and seventy age- and sex-matched controls were enrolled. The SDIs (percent of cardiac cycle) of 16 segments (16-SDI%) and 12 segments (12-SDI%) were calculated based on the defined standard deviation of each segment time from end diastole to the minimal systolic volume according to the 17-segment model (apex excluded). In the acute phase, the 16-SDI% and 12-SDI% were significantly higher in KD patients than in controls (4.40 ± 0.14 vs. 1.98 ± 0.12, P = 0.000; 3.55 ± 1.21 vs. 1.67 ± 0.93, P = 0.009, respectively), and patients with coronary artery aneurysm (CAA) exhibited higher 16-SDI% (P = 0.021) and 12-SDI% (P = 0.034) than patients without CAA. In the convalescent phase, patients with CAA still had higher 16-SDI% (P = 0.002) and 12-SDI% (P = 0.031) than controls, while the SDI in patients without CAA recovered to normal. The 16-SDI% was negatively correlated with the LV ejection fraction obtained from RT3DE (r = - 0.845, P = 0.000). Mechanical dyssynchrony is prevalent in KD patients during the acute phase and transient in patients without CAA, while patients with CAA still have impaired synchrony even in the convalescent phase. LV systolic dysfunction is associated with increased dyssynchrony. RT3DE is a valuable modality for identifying and quantifying dyssynchrony in KD patients.

2D/3D Echocardiographic features of patients with reverse remodeling after cardiac resynchronization therapy

PURPOSE

To describe clinical and echocardiographic characteristics associated with reverse left ventricular (LV) remodeling after 6 months of cardiac resynchronization therapy (CRT) in patients with nonischemic dilated cardiomyopathy.

METHODS

Twenty-four consecutive patients underwent 2D and 3D echocardiography before and after 6 months of CRT implant. Several echocardiographic parameters including global longitudinal strain (GLS) and 3D mechanical dyssynchrony (MD) index were calculated. CRT response was defined as a decrease in LV end-systolic volume (LVESV) of at least 10% at follow-up. Patients were divided in two groups according to CRT response.

RESULTS

Cardiac resynchronization therapy responder (CRTR+) rate was 50%. Nonresponder (CRTR-) patients showed a less significant improvement in NYHA class at follow-up. At baseline, CRTR- presented with higher LV end-diastolic volume (LVEDV) (P = 0.031), LVESV (P = 0.024), lower left ventricular ejection fraction (LVEF) (P = 0.002) and less negative GLS (P = 0.03), and with higher diastolic dysfunction, more impaired right ventricle (RV), and higher pulmonary artery systolic pressure (PASP) (P = 0.002). No significant differences in echocardiographic parameters of MD were found. Univariate determinants of CRTR+ were LVEF (OR = 1.59, CI 95% = 1.13-2.22, P = 0.007) and TAPSE (OR 1.21, CI 95% = 1.024-1.429, P = 0.025). A ROC curve analysis showed a cutoff value of LVEF of 22.15% significantly related to CRTR+ (SE 80%, SP 50%).

CONCLUSIONS

Our findings suggest that end-stage HF patients, presenting before CRT with LVEF <22.15%, may not benefit from the procedure after 6 months. Mechanical dyssyncronicity did not provide additional information to improve candidate selection.

The impact of multipole pacing on left ventricular function in patients with cardiac resynchronization therapy - A real-time three-dimensional echocardiography approach

BACKGROUND

Cardiac resynchronization therapy (CRT) is standard of care in heart failure (HF), however this technique is associated with a non-responder rate of 30%. Multipole pacing (MPP) with a quadripolar lead may optimize CRT and responder rate by creating two electrical wave fronts in the left ventricular (LV) myocardium simultaneously in order to reduce mechanical dyssynchrony. The objective of this study was to investigate the acute impact of MPP on LV function by assessing systolic dyssynchrony index (SDI) and left ventricular ejection fraction (LVEF) via real-time three-dimensional echocardiography (RT3DE).

METHODS

In 41 consecutive patients (87.8% male; mean age 66.0 ± 12.7 years) who received CRT defibrillators with a quadripolar LV lead, RT3DE datasets were acquired the day after implantation under the following pacing configurations: Baseline AAI, conventional biventricular pacing using distal or proximal LV poles and MPP. Datasets were analyzed in paired samples evaluating SDI and LVEF depending on programmed pacing modality.

RESULTS

MPP resulted in statistically significant reduction of SDI compared to baseline (6.3%; IQR 4.4-7.8 and 9.9%; IQR 8.0-12.7; p < 0.001) and to conventional biventricular pacing using distal (7.6%; IQR 6.5-9.1; p < 0.001) or proximal (7.4%; IQR 6.2-8.8; p < 0.001) LV poles respectively. MPP yielded significant increase in LVEF compared to baseline (30.6%; IQR 25.8-37.5 and 27.2%; IQR 21.1-33.6; p < 0.001) and to conventional biventricular pacing configuration with distal (28.1%; IQR 22.1-34.5; p < 0.001) or proximal (28.6%; IQR 23.2-34.9; p < 0.001) LV poles respectively.

CONCLUSIONS

Multipole pacing improves mechanical dyssynchrony of the left ventricular myocardium as assessed by SDI and LVEF.

Optimal site selection and image fusion guidance technology to facilitate cardiac resynchronization therapy

INTRODUCTION

Cardiac resynchronization therapy (CRT) has emerged as one of the few effective treatments for heart failure. However, up to 50% of patients derive no benefit. Suboptimal left ventricle (LV) lead position is a potential cause of poor outcomes while targeted lead deployment has been associated with enhanced response rates. Image-fusion guidance systems represent a novel approach to CRT delivery, allowing physicians to both accurately track and target a specific location during LV lead deployment.

AREAS COVERED

This review will provide a comprehensive evaluation of how to define the optimal pacing site. We will evaluate the evidence for delivering targeted LV stimulation at sites displaying favorable viability or advantageous mechanical or electrical properties. Finally, we will evaluate several emerging image-fusion guidance systems which aim to facilitate optimal site selection during CRT.

EXPERT COMMENTARY

Targeted LV lead deployment is associated with reductions in morbidity and mortality. Assessment of tissue characterization and electrical latency are critical and can be achieved in a number of ways. Ultimately, the constraints of coronary sinus anatomy have forced the exploration of novel means of delivering CRT including endocardial pacing which hold promise for the future of CRT delivery.

Current role of echocardiography in cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is an established treatment for patients with heart failure and left ventricular systolic dysfunction. Patients are usually assessed by echocardiography, which provides a number of anatomical and functional information used for cardiac dyssynchrony assessment, prognostic stratification, identification of the optimal site of pacing in the left ventricle, optimization of the CRT device, and patient follow-up. Compared to other cardiac imaging techniques, echocardiography has the advantage to be non-invasive, repeatable, and safe, without exposure to ionizing radiation or nefrotoxic contrast. In this article, we review current evidence about the role of echocardiography before, during, and after the implantation of a CRT device.

Assessment of left ventricular dyssynchrony by three-dimensional echocardiography: Prognostic value in patients undergoing cardiac resynchronization therapy

BACKGROUND

Systolic dyssynchrony index (SDI) using three-dimensional echocardiography (3DE) was shown to be a reliable measure of left ventricular (LV) dyssynchrony. However, the prognostic value of SDI on long-term outcomes after cardiac resynchronization therapy (CRT) remains unknown.

METHODS AND RESULTS

A total of 414 patients (mean age 67 ± 10 years, 60% ischemic etiology) with 3DE evaluation before CRT implantation were included. SDI was evaluated as continuous value and in quartiles. The study endpoint was combined all-cause mortality, heart transplantation, and LV assist device implantation. At baseline, median SDI was 8.0% (IQR 5.6-11.3%). During a median follow-up of 45 months (IQR 25-59 months), the endpoint was observed in 94 (23%) patients. SDI was independently associated with the endpoint together with ischemic etiology, diabetes, and renal function (HR 0.914, P = 0.003) after adjustment for age, atrial fibrillation, hemoglobin level, NYHA functional class, and posterolateral LV lead position. Patients from the 1st, 2nd, and 3rd SDI quartiles showed similar survival and superior as compared to the 4th quartile with the lowest SDI values (≤5.5%; χ²: 30.4, log-rank P < 0.001). From receiver operating characteristic curve analysis, the optimal SDI cut-off value associated with the endpoint was >6.8% (area under the curve 0.634). Finally, a subgroup analysis (293 patients) demonstrated that a more pronounced reduction in SDI immediately after CRT (resynchronization) was independently associated with superior survival (HR 0.461, P = 0.011) after adjustment for prognostic relevant parameters.

CONCLUSION

SDI is independently associated with long-term prognosis after CRT and might therefore be important to optimize risk-stratification in these patients.

Reverse remodelling and myocardial recovery in heart failure

Advances in medical and device therapies have demonstrated the capacity of the heart to reverse the failing phenotype. The development of normative changes to ventricular size and function led to the concept of reverse remodelling. Among heart failure therapies, durable mechanical circulatory support is most consistently associated with the largest degree of reverse remodelling. Accordingly, research to analyse human tissue after a period of mechanical circulatory support continues to yield a wealth of information. In this Review, we summarize the latest findings on reverse remodelling and myocardial recovery. Accumulating evidence shows that the molecular changes associated with heart failure, in particular in the transcriptome, metabalome, and extracellular matrix, persist in the reverse-remodelled myocardium despite apparent normalization of macrolevel properties. Therefore, reverse remodelling should be distinguished from true myocardial recovery, in which a failing heart regains both normal function and molecular makeup. These findings have implications for future research to develop therapies to repair fully the failing myocardium. Meanwhile, recognition by society guidelines of this new clinical phenotype, which is coming to be known as a state of heart failure remission, underscores the need to accurately define and identify reverse modelled myocardium for the establishment of appropriate therapies.

BMI influence on the reproducibility of ECG-gated myocardial perfusion imaging phase analysis in comparison with novel echocardiographic dyssynchrony estimation methods

AIM

Cardiac resynchronization therapy (CRT) is a treatment for patients with end-stage heart failure. However, two-thirds of the patients are nonresponders. Evaluation of left ventricular mechanical dyssynchrony may help in finding patients who will benefit from CRT. Dyssynchrony can be evaluated by the phase analysis method in myocardial perfusion imaging (MPI) or with cardiac ultrasound. The aim of this study was to investigate the reproducibility of phase analysis parameters in MPI and echocardiographic parameters in the evaluation of left ventricular mechanical dyssynchrony. In particular, the influence of BMI on reproducibility was studied.

METHODS AND RESULTS

Twenty-one patients underwent an ECG-gated MPI scan. Acquisition was repeated after the rest image. The patients were also studied twice with transthoracic echocardiography. Of MPI phase analysis parameters bandwidth, histogram SD and entropy% were highly reproducible in the pooled population: Cronbach's α 0.927-0.967 and intraclass correlation (ICC) 0.868-0.967, (P<0.001 for all). However, the reproducibility of bandwidth and SD was poorer in patients with BMI≥29 kg/m group (α 0.203 and -0.055; ICC 0.106 and -0.027, NS for both) than in those with BMI<29 kg/m (α 0.984 and 0.980; ICC 0.968 and 0.961, P<0.001 for both). In contrast, BMI had no obvious influence on the reproducibility of global longitudinal strain in echocardiography.

CONCLUSION

Parameters reflecting mechanical dyssynchrony were found to be well reproducible. However, this study indicates that phase analysis results may be less reproducible in patients with high BMI, whereas global longitudinal strain in echocardiography seems to be less critical for a patient's BMI.

Newer Echocardiographic Techniques in Cardiac Resynchronization Therapy

Echocardiographic imaging plays a major role in patient selection for cardiac resynchronization therapy (CRT). One-third of patients do not respond; there is interest in advanced echocardiographic imaging to improve response. Current guidelines favor CRT for patients with electrocardiographic (ECG) QRS width of 150 milliseconds or greater and left bundle branch block. ECG criteria are imperfect; there is interest in advanced echocardiographic imaging to improve patient selection. This discussion focuses on newer echocardiographic methods to improve patient selection, improve delivery, and identify patients at risk for poor outcomes and serious ventricular arrhythmias.

Left ventricular pacing vector selection by novel echo-particle imaging velocimetry analysis for optimization of quadripolar cardiac resynchronization device: a case report

Background

The availability of pacing configurations offered by quadripolar left ventricular leads could improve patients’ response to cardiac resynchronization therapy; however, the selection of an optimal setting remains a challenge. Echo-particle imaging velocimetry has shown that regional anomalies of synchrony/synergy of the left ventricle are related to the alteration, reduction, or suppression of the physiological intracavitary pressure gradients. These observations are also supported by several numerical models of the left ventricle that have shown the close relationship between wall motion abnormalities, change of intraventricular flow dynamics, and abnormal distribution of forces operating on the ventricular endocardium.

Case presentation

A 73-year-old white man in New York Heart Association III functional class with an ejection fraction of 27.5 % did not improve after 1 month of cardiac resynchronization therapy. Five configurations were tested and settings were defined by optimizing intraventricular flow. After 6 months, he became New York Heart Association II class with left ventricular ejection fraction of 53.2 %.

Conclusions

The abnormal dynamic of pressure gradients during the cardiac cycle, through biohumoral endocrine, autocrine, and paracrine transduction, may lead to structural changes of the myocardial walls with subsequent left ventricular remodeling. The echo-particle imaging velocimetry technique may be useful for elucidating the favorable effects of cardiac resynchronization therapy on intraventricular fluid dynamics and it could be used to identify appropriate pacing setting during acute echocardiographic optimization of left pacing vector.

Electronic supplementary material

The online version of this article (doi:10.1186/s13256-016-0965-9) contains supplementary material, which is available to authorized users.

Mitigation of Variability among 3D Echocardiography-Derived Regional Strain Values Acquired by Multiple Ultrasound Systems by Vendor Independent Analysis

Introduction

This study compared the variability of 3D echo derived circumferential and longitudinal strain values computed from vendor-specific and vendor-independent analyses of images acquired using ultrasound systems from different vendors.

Methods

Ten freshly harvested porcine hearts were studied. Each heart was mounted on a custom designed phantom and driven to simulate normal cardiac motion. Cardiac rotation was digitally controlled and held constant at 5°, while pumped stroke volume (SV) ranged from 30-70ml. Full-volume image data was acquired using three different ultrasound systems from different vendors. The image data was analyzed for longitudinal and circumferential strains (LS, CS) using both vendor-specific and vendor-independent analysis packages.

Results

Good linear relationships were observed for each vendor-specific analysis package for both CS and LS at the mid-anterior segment, with correlation coefficients ranging from 0.82–0.91 (CS) and 0.86–0.89 (LS). Comparable linear regressions were observed for results determined by a vendor independent program (CS: R = 0.82–0.89; LS: R = 0.86–0.89). Variability between analysis packages was examined via a series of ANOVA tests. A statistical difference was found between vendor-specific analysis packages (p<0.001), while no such difference was observed between ultrasound systems when using the vendor-independent program (p>0.05).

Conclusions

Circumferential and longitudinal regional strain values differ when quantified by vendor-specific analysis packages; however, this variability is mitigated by use of a vendor-independent quantification method. These results suggest that echocardiograms acquired using different ultrasound systems could be meaningfully compared using vendor-independent software.

Cardiac Resynchronization Therapy in Non-Ischemic Cardiomyopathy

Cardiac resynchronization therapy (CRT) is an established therapy for heart failure patients who remain symptomatic despite optimal medical therapy, have reduced left ventricular ejection fraction (<35%) and wide QRS duration (>120 ms), preferably with left bundle branch block morphology. The response to CRT depends on the cardiac substrate: presence of correctable left ventricular mechanical dyssynchrony, presence of myocardial fibrosis (scar) and position of the left ventricular pacing lead. Patients with non-ischemic cardiomyopathy have shown higher response rates to CRT compared with patients with ischemic cardiomyopathy. Differences in myocardial substrate may partly explain this disparity. Multimodality imaging plays an important role to assess the cardiac substrate and the pathophysiological determinants of response to CRT.

Newer Echocardiographic Techniques in Cardiac Resynchronization Therapy

Echocardiographic imaging plays a major role in patient selection for cardiac resynchronization therapy (CRT). One-third of patients do not respond; there is interest in advanced echocardiographic imaging to improve response. Current guidelines favor CRT for patients with electrocardiographic (ECG) QRS width of 150 milliseconds or greater and left bundle branch block. ECG criteria are imperfect; there is interest in advanced echocardiographic imaging to improve patient selection. This discussion focuses on newer echocardiographic methods to improve patient selection, improve delivery, and identify patients at risk for poor outcomes and serious ventricular arrhythmias.

Radionuclide Assessment of Left Ventricular Dyssynchrony

Phase analysis of gated myocardial perfusion single-photon emission computed tomography is a widely available and reproducible measure of left ventricular (LV) dyssynchrony, which also provides comprehensive assessment of LV function, global and regional scar burden, and patterns of LV mechanical activation. Preliminary studies indicate potential use in predicting cardiac resynchronization therapy response and elucidation of mechanisms. Because advances in technology may expand capabilities for precise LV lead placement in the future, identification of specific patterns of dyssynchrony may have a critical role in guiding cardiac resynchronization therapy.

Three-dimensional echocardiographic optimization improves outcome in cardiac resynchronization therapy compared to ECG optimization: a randomized comparison

AIMS

There is little consensus on optimal atrioventricular (AV) and ventricular-to-ventricular (VV) intervals in cardiac resynchronization therapy (CRT). The aim of this study was to examine a novel combination of Doppler echocardiography (DE) and three-dimensional echocardiography (3DE) for individualized AV- and VV-interval optimization compared to conventional electrocardiogram (ECG) optimization.

METHODS

In this double-blind, randomized controlled trial, 77 patients (male: 57, age: 68 ± 10 years) with severely reduced ejection fraction (EF), New York Heart Association (NYHA) class III or IV, and wide QRS complex (>120 ms) have been included. Patients were randomized to either AV- and VV-interval optimization using DE and 3DE (group 1, n = 39) or ECG (group 2, n = 38). 3DE was performed in all patients for the evaluation of left ventricular (LV) dimensions, EF and systolic dyssynchrony index (SDI), and NYHA class obtained before CRT and after 3 months. Primary endpoint of the study was clinical response to CRT, defined as a reduction of NYHA class by ≥1 score. Secondary endpoints were change of EF, LV volumes, and SDI.

RESULTS

There were significantly more responders in group 1 (82%) than in group 2 (58%, P = 0.021). Similarly, group 1 showed a larger increase in EF (7.0 ± 6.0% vs 3.4 ± 5.6%, P = 0.015) and a more pronounced reduction of SDI (-4.5 ± 5.9% vs -1.5 ± 5.6%, P = 0.039) than group 2.

CONCLUSION

Compared with conventional ECG optimization, this novel echocardiographic optimization protocol resulted in a significantly higher response rate, improved LV systolic function, and may be used to select the optimal AV and VV intervals in CRT.

Clinical implication of mechanical dyssynchrony in heart failure

Mechanical dyssynchrony is a common phenomenon in patients with congestive heart failure, which usually identified by noninvasive cardiac imaging tools such as echocardiography. It demonstrates electromechanical delay in some regions of the failing heart which in turn contributes to further impairment of cardiac function. The diagnostic, therapeutic and prognostic values of mechanical dyssynchrony have been reported in a number of studies. Therefore, this review describes briefly the methods of measurement, but more importantly, explains the clinical implication of its assessment in heart failure related aspects including cardiac resynchronization therapy, functional mitral regurgitation, diastolic heart failure and mortality.

Extraordinarily favorable left ventricular reverse remodeling through long-term cardiac resynchronization: super-response to cardiac resynchronization

BACKGROUND

Some chronic heart failure (CHF) patients show remarkable improvement in left ventricular (LV) remodeling after cardiac resynchronization therapy (CRT), for unclear reasons. This study aimed at identifying predictors of an extraordinarily favorable response to CRT.

METHODS

We studied 136 CRT patients (104 men, median 66 years, QRS 162 ms, left ventricular ejection fraction 24 ± 7%, 70% coronary disease, all left bundle branch block [LBBB]). We measured LV end diastolic diameter (LVEDD) before and after long-term (9.4 ± 6.3 months) CRT. At baseline, LV pre-ejection interval (LVPEI), interventricular mechanical delay (IVMD), LV dyssynchrony (standard deviation of electromechanical delays [SDEMD] in eight LV segments), exercise capacity (pVO(2)), and ventilatory efficiency (VE/VCO(2)) were assessed. Patients with a LVEDD reduction beyond the 80th percentile (high responders [HR]) were compared to low responders (LR).

RESULTS

In the HR group (n = 22), LVEDD was reduced from 71 to 52 mm (LR 64-61 mm, P < 0.001). HR had predominantly nonischemic heart disease (HR: 72%, LR: 44%, P = 0.019), tended to have a wider QRS (HR: 178 ms, LR: 162 ms, P = 0.066), had a longer LVPEI (HR: 179 ms, LR: 155 ms, P = 0.004), wider IVMD (HR: 60 ms, LR 48 ms, P = 0.05), larger LVEDD (P = 0.002), higher SDEMD (HR: 69 ms, LR: 46 ms, P = 0.044), but higher pVO(2) (HR: 17.5 mL/min/kg, LR: 13.5 mL/kg/min, P = 0.025) and lower VE/VCO(2) (HR: 31, LR: 35, P = 0.043), all compared to LR patients.

CONCLUSION

Extraordinarily favorable reverse LV remodeling through CRT in CHF and LBBB appears to require a particularly dilated LV due to nonischemic heart disease with pronounced electromechanical alteration, but with a fairly preserved functional capacity before CRT.

Current clinical applications of transthoracic three-dimensional echocardiography

The advent of three-dimensional echocardiography (3DE) has significantly improved the impact of non-invasive imaging on our understanding and management of cardiac diseases in clinical practice. Transthoracic 3DE enables an easier, more accurate and reproducible interpretation of the complex cardiac anatomy, overcoming the intrinsic limitations of conventional echocardiography. The availability of unprecedented views of cardiac structures from any perspective in the beating heart provides valuable clinical information and new levels of confidence in diagnosing heart disease. One major advantage of the third dimension is the improvement in the accuracy and reproducibility of chamber volume measurement by eliminating geometric assumptions and errors caused by foreshortened views. Another benefit of 3DE is the realistic en face views of heart valves, enabling a better appreciation of the severity and mechanisms of valve diseases in a unique, noninvasive manner. The purpose of this review is to provide readers with an update on the current clinical applications of transthoracic 3DE, emphasizing the incremental benefits of 3DE over conventional two-dimensional echocardiography.

Review of novel clinical applications of advanced, real-time, 3-dimensional echocardiography

Advances in computer processing speed and memory along with the advent of the microbeam former that can sample an entire crystal of the ultrasound transducer made possible the performance of 3-dimensional echocardiography in real time (RT3DE). The miniaturization of a 3-dimensional transducer permitting its extension to transesophageal mode rapidly expanded its use in a variety of conditions. Recent development of user-friendly automated/semiautomated cropping and display software may make it rather simple, even for the novice to gather useful information from RT3DE. We discuss the background, technique, and cutting-edge research and novel clinical applications of advanced RT3DE, including left ventricular dyssynchrony assessment, 3-D speckle tracking, myocardial contrast echocardiography, complete 4-dimensional (4-D) shape and motion analysis of the left ventricle, 4-D volumetric analysis of the right ventricle, 3-D volume rendering of the mitral valve, and other percutaneous and surgical procedural applications.

Acute beneficial hemodynamic effects of a novel 3D-echocardiographic optimization protocol in cardiac resynchronization therapy

BACKGROUND

Post-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.

METHODS

25 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).

RESULTS

EF 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).

CONCLUSIONS

Compared 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.

Quantitative analysis of left ventricular dyssynchrony using cardiac computed tomography versus three-dimensional echocardiography

OBJECTIVES

We investigated whether cardiac computed tomography (CCT) can determine intraventricular dyssynchrony in comparison to real-time three-dimensional echocardiography (RT3DE) in patients who are considered for cardiac resynchronisation therapy (CRT).

METHODS

35 patients considered for CRT were examined. Left ventricular (LV) dyssynchrony was quantified by calculating the standard deviation index (SDI) of 17 myocardial LV segments by RT3DE and ECG-gated contrast-enhanced 64-slice dual-source CCT. For both analyses the same software algorithm (4D LV-Analysis) was used.

RESULTS

Close correlations were observed for end-systolic volume, end-diastolic volume and LV ejection fraction between the two techniques (r = 0.94, r = 0.92 and r = 0.95, respectively, P < 0.001 for all). For the global dyssynchrony index SDI, a high correlation was found between RT3DE and CCT (r = 0.84, P < 0.001), which further increased after exclusion of segments with poor image quality by echocardiography (r = 0.90, P < 0.001). The required time for quantitative analysis was significantly shorter (162 ± 22 s vs. 608 ± 112 s per patient, P < 0.001) and reproducibility was significantly higher for CCT compared with RT3DE (interobserver variability of 4.5 ± 3.1% vs. 7.9 ± 6.1%, P < 0.05).

CONCLUSION

Quantitative assessment of LV dyssynchrony is feasible by CCT. Owing to its higher reproducibility and faster analysis time compared with RT3DE, this technique may represent a valuable alternative for dyssynchrony assessment.

KEY POINTS

• Quantitative assessment of left ventricular dyssynchrony is feasible by cardiac computed tomography (CCT). • This technique has been compared with real-time three-dimensional echocardiography (RT3DE). • Reproducibility is significantly higher for CCT compared with RT3DE. • Time spent for analysis is significantly shorter for CCT. • Computed tomography may represent a valuable alternative to ultrasound for dyssynchrony assessment.