Quantitation of left-ventricular asynergy by cardiac ultrasound

Effectiveness of real-time tele-ultrasound for echocardiography in resource-limited medical teams

BACKGROUND

Echocardiography is a first-line tool for the screening of patients with cardiac dysfunction. However, the mastery of echocardiography requires significant training, and not all medical teams involve an echocardiography specialist. Telemedicine approaches can potentially improve the quality of echocardiography in resource-limited situations.

METHODS

We used a novel tablet-based hand-held ultrasound device that enables tele-ultrasound- a real-time video telecommunication with remote control for ultrasound images. A trainee scanned patients with various cardiovascular diseases and interpreted the images. Subsequently, the same trainee re-scanned the same patients and re-interpreted the same images using tele-ultrasound with an echocardiography specialist. An examination on the same patients by a blinded specialist was considered the gold standard.

RESULTS

We included 31 patients (median 77 [interquartile range 68-84] years old, 42% women). Mean absolute errors in left ventricular (LV) end-diastolic and end-systolic diameters, visual LV ejection fraction, and tricuspid annular plane systolic excursion decreased significantly after tele-ultrasound advice (5.9 mm, 5.8 mm, 8.6%, and 4.5 to 1.6 mm, 2.8 mm, 0.7%, and 1.8 mm, respectively, all p < 0.001), and intra-class correlation coefficients improved (0.76, 0.84, 0.68, and 0.44 to 0.96, 0.93, 0.99, and 0.90, respectively). Notably, with tele-advice, the trainee's examination showed perfect agreement with that of the specialist in classifying LV ejection fraction (> 50%, 50-35%, or > 35%) and identifying significant valvular heart diseases.

CONCLUSION

Real-time tele-ultrasound improved a trainee's echocardiography results to those of a specialist-level examination. This approach might be helpful in resource-limited medical teams where echocardiographic specialists are not readily available.

Assessment of cardiac dyssynchrony by cardiac MR: A comparison of velocity encoding and feature tracking analysis

PURPOSE

To investigate whether cardiac magnetic resonance (cardiac MR)-based feature tracking (FT) may be used for robust and rapid quantification of dyssynchrony by measurement of the septal to lateral delay (SLD).

MATERIALS AND METHODS

Healthy volunteers (n = 18) and patients with mechanical dyssynchrony (n = 17) were investigated. Velocity encoding cardiac MR (VENC) and steady-state free precession (SSFP)-cine sequences were acquired in identical horizontal long axis (HLA) positions using a 1.5T MR scanner. Using FT and VENC cardiac MR software, myocardial velocity curves were calculated for the basal segment of the septal and lateral wall. Based on the quantity of dyssynchrony, the patients were classified into three subgroups (minimal, intermediate, extensive). SLD and patient classification were compared and intra- as well as interobserver variability assessed.

RESULTS

VENC and FT SLD measurements showed strong correlation (r = 0.94) and good agreement (mean 1.33 msec; limits of agreement [LoA] -2.96 to 5.63). Dyssynchrony subclassification based on FT was identical to VENC in 83% of the cases. While FT correctly classified all healthy subjects, three patients with mechanical dyssynchrony were misclassified. Compared to VENC, FT showed higher intra- and interobserver variability. VENC: intraobserver: mean 2.5 msec, LoA -17.5 to 22.5; interobserver: mean 1.5 msec, LoA -17.2 to 21.9. FT: intraobserver: mean 2.1 msec, LoA 27.6 to 31.8; interobserver: mean 2.4 msec LoA -31.4 to 34.5.

CONCLUSION

Cardiac MR-based FT analysis may be used for rapid appraisal of left ventricle cardiac dyssynchrony from SSFP images. However, FT results are less accurate and reproducible compared to VENC-based assessment of SLD.

Pathophysiological links, echocardiographic characteristics, and clinical implications of QRS morphology in patients with dilated cardiomyopathy

Heart failure is an important clinical problem worldwide. There is great interest in evaluating the relationship between electrocardiographic variations and dilated cardiomyopathy (DCM) since it has been used as a predictor of increased morbidity and mortality. The presence of fragmentation in the QRS complexes on 12-lead electrocardiogram (ECG) was reported as a marker of depolarization abnormality in patients with DCM. Previous studies have investigated the relation between QRS morphology and DCM. QRS morphology and duration are associated with clinical deterioration and increased mortality in patients with DCM. Although surface ECG provides valuable information on prognosis of these patients, echocardiographic methods have been used for further investigation of patients with DCM. The aim of the present review is to provide an overview of the pathophysiological links, echocardiographic characteristics and clinical implications of QRS morphology in patients with DCM.

Cardiac resynchronisation therapy associated with pulmonary artery banding in an adult with severe right ventricular dysfunction after Mustard repair for complete transposition of the great arteries: results after 2 years of follow-up

Late dysfunction of the systemic right ventricle in patients with complete transposition of the great arteries after Mustard or Senning procedures and progressive deterioration of the clinical status has been demonstrated. However, evidence-based data on the effective therapy for systemic right ventricular dysfunction in these patients are yet to be defined. Our patient shows an improvement in the right ventricular systolic function, with a reduction in tricuspid regurgitation and a consequent better exercise tolerance after a hybrid approach consisting of an upgrading of a previous transvenous-implanted dual-chamber Implantable Cardiac Defibrillator to biventricular pacing associated with pulmonary artery banding via an anterior thoracotomy.

Three-directional myocardial phase-contrast tissue velocity MR imaging with navigator-echo gating: in vivo and in vitro study

The study protocol was HIPAA compliant and institutional review board approved. Informed consent was obtained from all participants. The purpose of the study was to prospectively validate the capability of navigator-echo-gated phase-contrast magnetic resonance (MR) imaging for measurement of myocardial velocities in a phantom and to prospectively use the phase-contrast MR sequence to measure three-directional velocity in the myocardium in vivo in volunteers and in patients scheduled for cardiac resynchronization therapy. An excellent correlation between the measured velocity and the true phantom motion (R = 0.90 for longitudinal velocity, R = 0.93 for circumferential velocity) was observed. Myocardial velocities were successfully measured in 17 healthy volunteers (11 male, six female; mean age, 27.5 years +/- 6.5 [standard deviation]) and 28 patients with heart failure (18 male, 10 female; mean age, 63.9 years +/- 15.0). Velocity values were significantly lower in the patients than in the volunteers. The time to peak velocity in the lateral wall of the patients, as compared with that in the volunteers, was delayed. Phase-contrast MR imaging can be combined with navigator-echo gating to measure three-directional myocardial tissue velocities in vivo.

Evaluation of regional myocardial function using automated wall motion analysis of cine MR images: Contribution of parametric images, contraction times, and radial velocities

PURPOSE

To develop fast and robust procedures for a clinical evaluation of regional myocardial contractile function.

MATERIALS AND METHODS

Parametric analysis of main motion was applied to steady-state free-precession (SSFP) cine MR images. From the time-signal intensity curve associated with each pixel, parametric maps of mean high and low amplitudes and transition times between muscle and cavity were automatically computed. Then, regional time to first contraction, T(fc), mean contraction time, T(mc) and radial component of the endocardial velocity, V(m) were estimated from these parametric maps and a user-defined endocardial end-diastolic contour. The method was applied to short-axis slices in 22 subjects: eight controls, 13 myocardial infarctions (MIs), and one left bundle branch block (LBBB).

RESULTS

Typical patterns of normality and pathology on parametric maps are indicated. For controls, the mean values +/- standard deviations (SDs) of T(fc), T(mc), and V(m) were: 70 +/- 25 msec, 318 +/- 43 msec, and 4.6 +/- 1.8 cm second(-1). An apex to base gradient of T(fc), a significant septal delay in T(fc) and T(mc), and a decrease of V(m) between the lateral and septal walls were observed. For MI, T(fc) and T(mc) increased and V(m) decreased significantly in pathological segments. For LBBB, large delays were estimated in the septal wall.

CONCLUSION

The proposed method is promising for clinical assessment of regional wall contraction.

Assessment of left ventricular dyssynchrony in patients with heart failure and normal QRS duration

Cardiac resynchronization therapy (CRT) is an important component of heart failure therapy in patients with a left ventricular ejection fraction <35%, class III or ambulatory class IV symptoms, and a QRS duration >120 ms. The QRS duration criterion for patient selection is imperfect. About 30% of patients with an increased QRS duration are nonresponders to CRT and many with a normal QRS duration with mechanical dyssynchrony respond to CRT. The authors review the currently available echocardiographic tools for the assessment of ventricular dyssynchrony in patients with heart failure.

Prognostic value of tissue Doppler-derived ventricular asynchrony in patients with left bundle branch block but not advanced heart failure

OBJECTIVES

The aim of the present study was to evaluate the prognostic significance of tissue Doppler echocardiography (TDE)-derived ventricular asynchrony in patients with left bundle branch block (LBBB) but not advanced heart failure.

METHODS

Fifty-five patients (mean age 66 +/- 13 years; 33 male) with complete LBBB (QRS > 120 ms) hospitalized for an acute episode of decompensated heart failure and in New York Heart Association class II for at least 6 months before the study admission underwent standard Doppler echo and pulsed-wave TDE. Precontraction time (PCTm) from the beginning of Q wave of electrocardiogram to the onset of systolic myocardial velocity wave was evaluated in four different left ventricular (LV) basal myocardial segments (LV anterior, inferior, septal and lateral walls) and in one right ventricular (RV) lateral wall. Intraventricular activation delay (IntraV-del) was calculated by the difference of PCTm of each LV myocardial segment. Interventricular activation delay (InterV-del) was calculated by the difference of PCTm between the most delayed LV segment and RV lateral wall.

RESULTS

The mean value of EF was 40 +/- 9% and of InterV-del, IntraV-del was, respectively (97.4 +/- 46.7 and 57.9 +/- 35.5 ms). InterV-del was inversely related to EF (r = -0.68; P < 0001). During the follow-up (26 months, range 11-37 months) cardiac events were recorded in 23 (41%) patients: a worsening of heart failure (WHF) in 23 patients and cardiac death in ten patients. Cox proportional hazard multivariate analysis showed that age, and InterV-del [HR = 1.02 (P < 0.05) and 1.03 (P < 0005)] predicted mortality. A Receiver operating characteristic analysis showed that a cut-off value of InterV-del 100 ms (AUC = 0.86; P < 0001) predicted WHF and mortality with sensitivity and specificity of 75% and 90%; 81% and 84%, respectively.

CONCLUSIONS

TDE-derived interventricular asynchrony represents a prognostic indicator of major cardiac events at 2 years of follow-up in patients with LBBB but not advanced heart failure.

Cardiac tissue Doppler imaging in sports medicine

The differentiation of training-induced cardiac adaptations from pathological conditions is a key issue in sports cardiology. As morphological features do not allow for a clear delineation of early stages of relevant pathologies, the echocardiographic evaluation of left ventricular function is the technique of first choice in this regard. Tissue Doppler imaging (TDI) is a relatively recent method for the assessment of cardiac function that provides direct, local measurements of myocardial velocities throughout the cardiac cycle. Although it has shown a superior sensitivity in the detection of ventricular dysfunction in clinical and experimental studies, its application in sports medicine is still rare. Besides technical factors, this may be due to a lack in consensus on the characteristics of ventricular function in relevant conditions. For more than two decades there has been an ongoing debate on the existence of a supernormal left ventricular function in athlete's heart. While results from traditional echocardiography are conflicting, TDI studies established an improved diastolic function in endurance-trained athletes with athlete's heart compared with controls.The influence of anabolic steroids on cardiac function also has been investigated by standard echocardiographic techniques with inconsistent results. The only TDI study dealing with this topic demonstrated a significantly impaired diastolic function in bodybuilders with long-term abuse of anabolic steroids compared with strength-trained athletes without abuse of anabolic steroids and controls, respectively.Hypertrophic cardiomyopathy is the most frequent cause of sudden death in young athletes. However, in its early stages, it is difficult to distinguish from athlete's heart. By means of TDI, ventricular dysfunction in hypertrophic cardiomyopathy can be disclosed even before the development of left ventricular hypertrophy. Also, a differentiation of left ventricular hypertrophy due to hypertrophic cardiomyopathy or systemic hypertension is possible by TDI. Besides the evaluation of different forms of left ventricular hypertrophy, the diagnosis of myocarditis is also of particular importance in athletes. Today, it still requires myocardial biopsy. The analysis of focal disturbances in myocardial velocities might be a promising non-invasive method; however, systematic validation studies are lacking. An important future issue for the implementation of TDI into routine examination will be the standardisation of procedures and the establishment of significant reference values for the above-mentioned conditions. Innovative TDI parameters also merit further investigation.

Qualitative observation of left ventricular multiphasic septal motion and septal-to-lateral apical shuffle predicts left ventricular reverse remodeling after cardiac resynchronization therapy

A multiphasic septal motion and typical septal-to-lateral apical shuffle of the left ventricle can be observed echocardiographically in some patients with left branch bundle block. The relation of both with left ventricular (LV) dyssynchrony according to tissue Doppler and LV reverse remodeling after cardiac resynchronization therapy was investigated. Fifty-three patients (37 men; age 68+/-8 years) with ischemic (n=26) or idiopathic (n=27) cardiomyopathy, baseline QRS duration 171+/-30 ms, LV ejection fraction 21+/-7%, and LV end-diastolic volume 257+/-91 ml were studied. LV dyssynchrony using tissue Doppler was considered present if the SD of the interval between QRS and onset of systolic velocity of 6 basal LV segments was >20 ms. Shuffle was evaluated visually independently by 5 cardiologists and considered present if observed in>or=1 view. LV reverse remodeling, defined as LV end-systolic volume decrease>or=10%, was observed in 37 patients (70%) after 3 months of CRT. Sensitivity and specificity of either shuffle or multiphasic septal motion for all 5 observers (range 90% to 97% and 67% to 83%, respectively) were found to predict LV dyssynchrony. To predict LV reverse remodeling, sensitivity and specificity from 87% to 92% and 69% to 81% were observed, respectively. In conclusion, the qualitative observation of a typical shuffle or multiphasic septal motion predicts LV dyssynchrony and LV reverse remodeling adequately.

Usefulness of Ventricular Longitudinal Contractility Assessed by Doppler Tissue Imaging in the Prediction of Reverse Remodeling in Patients with Severe Left Ventricular Systolic Dysfunction

OBJECTIVE

We sought to test if assessment of ventricular longitudinal contractility (LC) by Doppler tissue imaging (DTI) can predict reverse remodeling (RR) of left ventricular (LV) dysfunction resulting from medical treatment.

METHODS

DTI was performed in 35 patients with nonischemic LV dysfunction (ejection fraction 26 +/- 7%) and LC was assessed at the 4 different basal segments of the LV walls (septal, lateral, inferior, and anterior) using myocardial velocity curves and strain measurements; the peak systolic or delayed longitudinal contraction velocity of LV walls only with concomitant negative strain were measured and added to represent LC of each patient (LC by DTI). Successful RR was defined as a reduction of LV end-systolic volume of greater than 15%.

RESULTS

RR was observed in 13 patients (37%, group A). Initial LV ejection fraction was similar in patients who did and did not achieve RR (group B). Compared with group B, group A showed shorter QRS interval (110 +/- 36 vs 136 +/- 28 milliseconds, P = .022), shorter symptom duration (2.3 +/- 3.5 vs 4.2 +/- 3.4 years, P = .047), lower prevalence of left bundle branch block (23% vs 59%, P = .039), and higher value of LC by DTI (9.6 +/- 3.5 vs 6.3 +/- 3.6 cm/s, P = .011). Multivariate analysis revealed that symptom duration less than 2 years (odds ratio = 8.0, 95% confidence interval = 1.3-47.2, P = .022) and LC by DTI (odds ratio = 1.3, 95% confidence interval = 1.0-1.7, P = .019) were independent predictors of RR.

CONCLUSIONS

DTI provides a new index of LC, which is useful for predicting RR in patients with severe LV dysfunction.

Comparison of myocardial velocities obtained with magnetic resonance phase velocity mapping and tissue doppler imaging in normal subjects and patients with left ventricular dyssynchrony

PURPOSE

To compare longitudinal myocardial velocity and time to peak longitudinal velocity obtained with magnetic resonance phase velocity mapping (MR-PVM) and tissue Doppler imaging (TDI), and to assess the reproducibility of each method.

MATERIALS AND METHODS

Longitudinal myocardial velocity was measured by TDI and MR-PVM in 10 normal volunteers and 10 patients with dyssynchrony. The reproducibility of MR-PVM and TDI was assessed on repeated measurements in the 10 normal volunteers.

RESULTS

MR and TDI measurements of longitudinal myocardial velocity correlated well (r = 0.86) in both normal subjects and patients with dyssynchrony. However, myocardial velocities measured with MR consistently exceeded velocities measured with TDI. MR and TDI agreed strongly in measuring the time to peak velocity (r = 0.97). The reproducibility of TDI and MR-PVM appeared similar in measuring peak velocities (13.1% vs. 11.0%, respectively; P = NS) and time to peak velocity (9.1% vs. 5.7%, respectively; P = NS).

CONCLUSION

Excellent correlation and reproducibility were observed between MR-PVM and TDI in measuring longitudinal myocardial velocity and time to peak velocity in both normal subjects and patients with dyssynchrony.

Tissue Doppler echocardiographic quantification. Comparison to coronary angiography results in Acute Coronary Syndrome patients

Background

Multiples indices have been described using tissue Doppler imaging (DTI) capabilities. The aim of this study was to assess the capability of one or several regional DTI parameters in separating control from ischemic myocardium.

Methods

Twenty-eight patients with acute myocardial infarction were imaged within 24-hour following an emergent coronary angioplasty. Seventeen controls without any coronary artery or myocardial disease were also explored. Global and regional left ventricular functions were assessed. High frame rate color DTI cineloop recordings were made in apical 4 and 2-chamber for subsequent analysis. Peak velocity during isovolumic contraction time (IVC), ejection time, isovolumic relaxation (IVR) and filling time were measured at the mitral annulus and the basal, mid and apical segments of each of the walls studied as well as peak systolic displacement and peak of strain.

Results

DTI-analysis enabled us to discriminate between the 3 populations (controls, inferior and anterior AMI). Even in non-ischemic segments, velocities and displacements were reduced in the 2 AMI populations. Peak systolic displacement was the best parameter to discriminate controls from AMI groups (wall by wall, p was systematically < 0.01). The combination IVC + and IVR< 1 discriminated ischemic from non-ischemic segments with 82% sensitivity and 85% specificity.

Conclusion

DTI-analysis appears to be valuable in ischemic heart disease assessment. Its clinical impact remains to be established. However this simple index might really help in intensive care unit routine practice.

Quantitative regional analysis of left atrial function by Doppler tissue imaging–derived parameters discriminates patients with posterior and anterior myocardial infarction

BACKGROUND

Doppler tissue imaging can now be used for the assessment of left atrial (LA) function. LA function was evaluated by this technique in a group of patients hospitalized for acute myocardial infarction and in a control population.

METHODS

Patients were all prospectively imaged with a scanner. To study the LA, a region of interest was located in the proximal part of the lateral and septal LA walls. Doppler tissue imaging, tissue tracking, strain, and delays were recorded.

RESULTS

In all, 12 patients with posterior (age 54 +/- 9 years) and 13 with anterior (age 64 +/- 16 years) acute myocardial infarction, along with 16 control patients (age 54 +/- 9 years), were analyzed. Early diastolic septal velocity was found to be the best parameter for discriminating among the 3 groups. Peak strain was also relevant and did not correlate with left ventricular function.

CONCLUSIONS

LA is accessible to Doppler tissue imaging analysis. Strain can quantify LA function relatively independently of left ventricular function, and may provide new insights on LA function.

Echocardiographic evaluation of cardiac resynchronization therapy: ready for routine clinical use?

Cardiac resynchronization therapy (CRT) has been proposed as an alternative treatment in patients with severe, drug-refractory heart failure. The clinical results are promising, and improvement in symptoms, exercise capacity, and systolic left ventricular (LV) function have been demonstrated after CRT, accompanied by a reduction in hospitalization and a superior survival as compared with optimized medical therapy alone. However, 20% to 30% of patients do not respond to CRT. Currently, patients are selected mainly on electrocardiogram criteria (wide QRS complex, left bundle branch block configuration). In view of the 20% to 30% of nonresponders, additional selection criteria are needed. Echocardiography (and, in particular, tissue Doppler imaging) may allow further identification of potential responders to CRT, based on assessment of inter- and intraventricular dyssynchrony. In addition, echocardiography may allow optimal LV lead positioning and follow-up after CRT. In the current review, the different echocardiographic approaches to predict response to CRT are discussed. In addition, the use of echocardiography to guide LV lead positioning and follow-up after CRT are addressed.

In vitro evaluation of ultrasound Doppler strain rate imaging: modification for measurement in a slowly moving tissue phantom

Doppler strain rate imaging (SRI) was evaluated in vitro using a silicone strip phantom mimicking slowly moving tissue. A test apparatus was developed that enabled controlled strain experiments with variable strain and strain rate to be performed. SRI strain was measured at eight different calculated strains (range 5.7 to 63.4 %) at three different pump speeds with tissue velocity 0.1, 0.5 and 1.0 mm/s. The effect of varying tissue velocity and strain sample size on the measured SRI strain was elaborated. SRI strains agreed well with calculated values for strain when SRI strain was measured as the average over the whole strip cross-section and the strain sample size was 1.9 mm (mean difference = 2.78%, limits of agreement +/- 9.97% for tissue velocity 1.0 mm/s, n = 8). The variance was substantial if single central samples were used, especially for strain sample size of 0.8 mm (mean difference = -7.47%, limits of agreement +/- 20.90 for tissue velocity 0.5 mm/s, n = 24). Increasing the strain sample size to 1.9 mm removed some of the underestimation (giving mean difference of -4.46%, n = 24). We found low intra- and interobserver variation. This study indicates that, for the SRI method to give accurate estimates of strain, strain sample size should be in the region of 2 mm. Averaging over several ultrasound (US) beams increased the accuracy further.

Interventricular and intraventricular dyssynchrony in idiopathic dilated cardiomyopathy: a prognostic study with fourier phase analysis of radionuclide angioscintigraphy

OBJECTIVES

The study evaluated the prognostic value of interventricular and intraventricular dyssynchrony in idiopathic dilated cardiomyopathy (IDC).

BACKGROUND

Biventricular pacing is an emerging treatment for patients with dilated cardiomyopathy and ventricular dyssynchrony. The prognostic values of interventricular and intraventricular dyssynchrony have not been previously compared.

METHODS

A total of 103 patients with IDC were studied. Left bundle branch block was present in 25% of patients. Equilibrium radionuclide angiography was performed and Fourier phase analyses were examined in both ventricles. Difference between the mean phase of left ventricle (LV) and right ventricle (RV) assessed interventricular dyssynchrony, and standard deviations (SDs) of the mean phase in each ventricle assessed intraventricular dyssynchrony.

RESULTS

The QRS duration was related to both interventricular and intraventricular dyssynchrony. A degradation of the hemodynamic status was associated with an increase in intraventricular dyssynchrony but not in interventricular dyssynchrony. With a follow-up of 27 +/- 23 months, 18 patients had a major cardiac event (7 cardiac deaths; 11 worsening, leading to heart transplantation). The SDs of the LV and RV mean phase and QRS duration were predictors of cardiac event (all p < 0.0001), but interventricular dyssynchrony was not. Among 13 univariate predictors of cardiac event, the only independent predictors were an increased SD of LV mean phase (p = 0.0004) and an increased pulmonary capillary wedge pressure (p = 0.009).

CONCLUSIONS

Intraventricular dyssynchrony evaluated with phase analysis of radionuclide angiography is an independent predictor of cardiac event in IDC. The prognosis is related to intraventricular rather than to interventricular dyssynchrony in IDC.

High temporal resolution phase contrast MRI with multiecho acquisitions

Velocity imaging with phase contrast (PC) MRI is a noninvasive tool for quantitative blood flow measurement in vivo. A shortcoming of conventional PC imaging is the reduction in temporal resolution as compared to the corresponding magnitude imaging. For the measurement of velocity in a single direction, the temporal resolution is halved because one must acquire two differentially flow-encoded images for every PC image frame to subtract out non-velocity-related image phase information. In this study, a high temporal resolution PC technique which retains both the spatial resolution and breath-hold length of conventional magnitude imaging is presented. Improvement by a factor of 2 in the temporal resolution was achieved by acquiring the differentially flow-encoded images in separate breath-holds rather than interleaved within a single breath-hold. Additionally, a multiecho readout was incorporated into the PC experiment to acquire more views per unit time than is possible with the single gradient-echo technique. A total improvement in temporal resolution by approximately 5 times over conventional PC imaging was achieved. A complete set of images containing velocity data in all three directions was acquired in four breath-holds, with a temporal resolution of 11.2 ms and an in-plane spatial resolution of 2 mm x 2 mm.