Comparison between tissue Doppler imaging and velocity-encoded magnetic resonance imaging for measurement of myocardial velocities, assessment of left ventricular dyssynchrony, and estimation of left ventricular filling pressures in patients with ischemic cardiomyopathy

Impact of the evaluation method on 4D flow-derived diastolic transmitral and myocardial peak velocities: Comparison with echocardiography

PURPOSE

To compare agreement of different evaluation methods of magnetic resonance (MR) 4D flow-derived diastolic transmitral and myocardial peak velocities as well as their ratios, using echocardiography as reference.

METHODS

In this prospective study, 60 subjects without symptoms of cardiovascular disease underwent echocardiography and non-contrast 3 T MR 4D flow imaging of the heart. Early- (E) and late-diastolic (A) transmitral peak filling velocities were evaluated from 4D flow data using three different strategies: 1) at the mitral valve tips in short-axis orientation (SA-method), 2) between the mitral valve tips in 4-chamber orientation (4-chamber-method), and 3) as maximal velocities in the transmitral inflow volume (max-velocity-method). Septal, lateral and average early-diastolic myocardial peak velocities (e') were derived from the myocardial tissue in the vicinity of the mitral valve. 4D flow parameters were compared with echocardiography by correlation and Bland-Altman analysis.

RESULTS

All 4D flow-derived E, A and E/A values correlated with echocardiography (r = 0.65-0.73, 0.75-0.83 and 0.74-0.86, respectively). While the SA- and 4-chamber-methods substantially underestimated E and A compared to echocardiography (p < 0.001), the max-velocity-method provided E (p = 0.13) and E/A (p = 0.07) without significant bias. Septal, lateral and average e' from 4D flow as well as the max-velocity-method-derived E/e' correlated with echocardiographic measurements (r = 0.64-0.81) and showed no significant bias (p = 0.26-0.54).

CONCLUSION

MR 4D flow imaging allows precise and accurate evaluation of transmitral and myocardial peak velocities for characterization of LV diastolic function without significant bias to echocardiography, when transmitral velocities are assessed from the transmitral inflow volume. This enables the use of validated echocardiography threshold values.

Right ventricular diastolic function in aging: a head-to-head comparison between phase-contrast MRI and Doppler echocardiography

To evaluate right ventricle (RV) diastolic function from phase-contrast MRI (PC-MRI) in aging. 89 healthy individuals (50 men, 43 ± 15 years) underwent cardiac MRI including 2D PC-MRI (1.5T) and reference Doppler echocardiography of both ventricles on the same day. Conventional echocardiographic parameters were estimated: early (E, cm/s) and atrial (A) peak velocities as well as myocardial early peak longitudinal velocity (E'). PC-MRI images were analyzed using custom software, providing: E', E and A waves along with respective peak flow rates (Ef, Af, mL/s) and filling volume (mL), for both ventricles. Intra- and inter-observer reproducibility was studied in 30 subjects and coefficients of variation (CoV) as well as intra-class correlation coefficients (ICC) were provided. RV diastolic function indices derived from PC-MRI data were reproducible (CoV ≤ 21%, ICC ≥ 0.75) and reliable as reflected by significant associations with left ventricular diastolic function indices assessed using both echocardiography (linear regression Pearson correlation coefficient r ≤ 0.59) and PC-MRI (r ≤ 71). Despite the fair associations between RV echocardiography and PC-MRI (r ≤ 0.25), the highest correlation with age was obtained for MRI Ef/Af ratio (r = - 0.64, p < 0.0001 vs. r = - 0.40, p = 0.0001 for echocardiographic E/A). Among PC-MRI E/A ratios, highest correlations with age were observed for flow rate and mean velocity ratios (r = - 0.61, p < 0.0001) as compared to maximal velocity ratios (r = - 0.56, p < 0.0001). Associations with age for E' were equivalent between PC-MRI (mean velocity: r = - 0.40, p < 0.0001; maximal velocity: r = - 0.36, p = 0.0005) and echocardiography (r = - 0.36, p = 0.0006). Finally, the significant and age-independent associations between RV mass/end-diastolic volume and E' were stronger for PC-MRI (mean velocity: r = - 0.36, p = 0.0006; maximal velocity: r = - 0.28, p = 0.007) than echocardiography (r = - 0.09, p = 0.38). PC-MRI tricuspid inflow and annulus myocardial velocity parameters were reproducible and able to characterize age-related variations in RV diastolic function.

Mitral annular velocity measurement with cardiac magnetic resonance imaging using a novel annular tracking algorithm: Validation against echocardiography

BACKGROUND

Doppler based mitral annular velocities are an integral part of echocardiographic left ventricular diastolic function assessment. Although these measurements can be obtained by phase contrast cardiac magnetic resonance imaging (PC-CMR), this approach has limitations. The aims of this study were to assess the accuracy and reproducibility of a high temporal resolution steady-state free precession (SSFP) cine acquisition coupled with semi-automated mitral annular tracking to measure tissue velocity, and compare to echocardiography as the reference method.

METHODS

High temporal resolution (17 ms) 4-chamber cines were acquired in 25 volunteers using retrospective and prospective gating on a 3.0 T magnet. Mitral annular early (e') and late (a') tissue velocities were derived using a novel algorithm to semi-automatically detect the mitral valve insertion points and track its motion. Additionally, PC-CMR was used to measure mitral inflow early diastolic (E) velocity. Those measurements were also obtained using echocardiography based pulsed and tissue Doppler techniques, on the same day.

RESULTS

Subjects were on average 34 ± 14 years-old (48% male). The lateral annulus e' measurements had the best agreement with echocardiography with a concordance correlation coefficient (CCC) of 0.76 and 0.75 for prospectively and retrospectively gated cine CMR respectively. There was no significant difference in the lateral annular tissue velocities between echocardiography (13.8 ± 3.7 cm/s) and prospective (13.4 ± 3.7 cm/s) or retrospective (14.0 ± 3.7) acquisitions. Similarly, CMR measurement of E/e' (a surrogate marker for LV filling pressures) using the lateral e' velocity showed moderate agreement with echocardiography (CCC of 0.56 and 0.51 for prospective and retrospective acquisitions respectively) without a significant difference in ratios (5.3 ± 1.6 and 5.0 ± 1.3) compared to echocardiography (5.2 ± 1.4). Intra- and inter-observer reproducibility of the CMR-based annular velocity measurements was good.

CONCLUSION

Measurements of mitral annular tissue velocities can be obtained from SSFP 4-chamber cine images using a semi-automated annular tracking algorithm, and demonstrates moderate agreement with echocardiography. The semi-automated method can provide quantitative mitral annular velocity measurements directly from conventional cine images, thereby providing additional clinically relevant information. The accuracy of this method in patients with diastolic dysfunction remains to be determined.

Segmental biventricular analysis of myocardial function using high temporal and spatial resolution tissue phase mapping

OBJECTIVE

Myocardial dysfunction of the right ventricle (RV) is an important indicator of RV diseases, e.g. RV infarction or pulmonary hypertension. Tissue phase mapping (TPM) has been widely used to determine function of the left ventricle (LV) by analyzing myocardial velocities. The analysis of RV motion is more complicated due to the different geometry and smaller wall thickness. The aim of this work was to adapt and optimize TPM to the demands of the RV.

MATERIALS AND METHODS

TPM measurements were acquired in 25 healthy volunteers using a velocity-encoded phase-contrast sequence and kt-accelerated parallel imaging in combination with optimized navigator strategy and blood saturation. Post processing was extended by a 10-segment RV model and a detailed biventricular analysis of myocardial velocities was performed.

RESULTS

High spatio-temporal resolution (1.0 × 1.0 × 6 mm³, 21.3 ms) and the optimized blood saturation enabled good delineation of the RV and its velocities. Global and segmental velocities, as well as time to peak velocities showed significant differences between the LV and RV. Furthermore, complex timing of the RV could be demonstrated by segmental time to peak analysis.

CONCLUSION

High spatio-temporal resolution TPM enables a detailed biventricular analysis of myocardial motion and might provide a reliable tool for description and detection of diseases affecting left and right ventricular function.

Three-Dimensional Volumetric Assessment of Diastolic Function by Cardiac Magnetic Resonance Imaging: The Multi-Ethnic Study of Atherosclerosis (MESA)

Background:

Cardiac Magnetic Resonance is in need of a simple and robust method for diastolic function assessment that can be done with routine protocol sequences.

Objective:

To develop and validate a three-dimensional (3D) model-based volumetric assessment of diastolic function using cardiac magnetic resonance (CMR) imaging and compare the results obtained with the model with those obtained by echocardiography.

Methods:

The study participants provided written informed consent and were included if having undergone both echocardiography and cine steady-state free precession (SSFP) CMR on the same day. Guide points at the septal and lateral mitral annulus were used to define the early longitudinal relaxation rate (E'), while a time-volume curve from the 3D model was used to assess diastolic filling parameters. We determined the correlation between 3D CMR and echocardiography and the accuracy of CMR in classifying the diastolic function grade.

Results:

The study included 102 subjects. The E/A ratio by CMR was positively associated with the E/A ratio by echocardiography (r = 0.71, p < 0.0001). The early diastolic relaxation velocity by tissue Doppler and longitudinal relaxation rate for the lateral mitral annulus displacement were positively associated (p = 0.007), as were the ratio between Doppler E/e' and CMR E/E' (p = 0.01). CMR-determined normalized peak E (NE) and deceleration time (DT) were able to predict diastolic dysfunction (areas under the curve [AUCs] = 0.70 and 0.72, respectively). In addition, the lateral E/E' ratio showed good utility in identifying diastolic dysfunction (AUC = 0.80). Overall, echocardiography and CMR interobserver and intraobserver agreements were excellent (intraclass correlation coefficient range 0.72 - 0.97).

Conclusion:

3D modeling of standard cine CMR images was able to identify study subjects with reduced diastolic function and showed good reproducibility, suggesting a potential for a routine diastolic function assessment by CMR.

Fundamento:

A ressonância magnética cardíaca necessita de um método simples e robusto para a avaliação da função diastólica que pode ser feito com sequências protocolares de rotina.

Objetivo:

Desenvolver e validar a avaliação volumétrica da função diastólica através de um modelo tridimensional (3D) com utilização de imagens de ressonância magnética cardíaca (RMC) e comparar os resultados obtidos com este modelo com os obtidos por ecocardiografia.

Métodos:

Os participantes do estudo assinaram um termo de consentimento e foram incluídos se tivessem sido submetidos no mesmo dia tanto à ecocardiografia quanto à cine RMC com precessão livre no estado estacionário (steady-state free precession, SSFP). Pontos-guia foram utilizados no anel mitral septal e lateral para definir a velocidade de estiramento no início da diástole (E'), enquanto curvas de volume-tempo do modelo 3D foram utilizadas para avaliar os parâmetros de enchimento diastólico. Foram determinadas a correlação entre a RMC 3D e a ecocardiografia, além da acurácia da RMC em classificar o grau de função diastólica.

Resultados:

Ao todo, 102 sujeitos foram incluídos no estudo. A razão E/A pela RMC esteve positivamente associada com a razão E/A obtida pela ecocardiografia (r = 0,71, p < 0,0001). Estiveram positivamente associadas a velocidade de relaxamento diastólico inicial ao Doppler tecidual e a velocidade de relaxamento longitudinal de deslocamento do anel mitral lateral (p = 0,007), bem como a razão entre E/e' por Doppler e E/E' pela RMC (p = 0,01). A velocidade normalizada de pico de enchimento (EM) determinada pela RMC e o tempo de desaceleração (TD) foram capazes de predizer a disfunção diastólica (áreas sob a curva [AUCs] = 0,70 e 0,72, respectivamente). Além disso, a razão E/E' lateral mostrou boa utilidade para a identificação da disfunção diastólica (AUC = 0,80). No geral, a ecocardiografia e a RMC apresentaram excelente concordância interobservador e intraobservador (coeficiente de correlação intraclasse 0,72 - 0,97).

Conclusão:

Uma modelagem 3D de imagens padrões de cine RMC foi capaz de identificar os indivíduos do estudo com função diastólica reduzida e mostrou uma boa reprodutibilidade, sugerindo ter potencial na avaliação rotineira da função diastólica por RMC.

Comparison between a count-based and geometrical approach for the assessment of left ventricular dyssynchrony using myocardial perfusion scintigraphy

OBJECTIVE

There are two distinct approaches for the assessment of left ventricular (LV) dyssynchrony by myocardial perfusion scintigraphy (MPS). The aim of this study was to compare the performance of the count-based and geometrical approach in clinical data using gated single photon emission computed tomography MPS.

MATERIAL AND METHODS

Group 1 consisted of 113 patients (49 men, 64 women) with normal perfusion [summed rest score (SRS)≤3], normal LV ejection fraction (≥55%), and normal QRS duration (QRSd<120 ms). Group 2 consisted of 89 heart failure patients (79 men, 10 women) with no restriction for SRS, LV ejection fraction ≤35%, and QRSd ≥120 ms. All MPS parameters were obtained from the software Corridor4DM. Dyssynchrony parameters used were time to peak contraction, SD, and bandwidth (BW).

RESULTS

SD and BW were estimated higher (difference group 1: SD 3.0±2.3 and BW 11.3±9.3, P-values <0.001; difference group 2: SD 2.4±4.3 and BW 1.3±17.0, P-value <0.001 and 0.479 respectively) using the count-based approach in comparison with the geometrical method. A significant and good correlation was found between these two methods (R=0.763, 0.902, 0.896 for time to peak contraction, SD, and BW respectively, P-values ≤0.001). SD and BW in both approaches were equally good parameters for differentiating heart failure patients (area under the curve: 0.995-0.998), although using different cut-off values.

CONCLUSION

The count-based approach generally provides a wider phase distribution and subsequently greater SD and BW estimates compared with the geometrical algorithm. These differences result in clinically relevant deviations in normal and cut-off values that have to be recognized when evaluating patients.

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.

A non-invasive assessment of cardiopulmonary hemodynamics with MRI in pulmonary hypertension

PURPOSE

We propose a method for non-invasive quantification of hemodynamic changes in the pulmonary arteries resulting from pulmonary hypertension (PH).

METHODS

Using a two-element Windkessel model, and input parameters derived from standard MRI evaluation of flow, cardiac function and valvular motion, we derive: pulmonary artery compliance (C), mean pulmonary artery pressure (mPAP), pulmonary vascular resistance (PVR), pulmonary capillary wedge pressure (PCWP), time-averaged intra-pulmonary pressure waveforms and pulmonary artery pressures (systolic (sPAP) and diastolic (dPAP)). MRI results were compared directly to reference standard values from right heart catheterization (RHC) obtained in a series of patients with suspected pulmonary hypertension (PH).

RESULTS

In 7 patients with suspected PH undergoing RHC, MRI and echocardiography, there was no statistically significant difference (p<0.05) between parameters measured by MRI and RHC. Using standard clinical cutoffs to define PH (mPAP>25mmHg), MRI was able to correctly identify all patients as having pulmonary hypertension, and to correctly distinguish between pulmonary arterial (mPAP>25mmHg, PCWP<15mmHg) and venous hypertension (mPAP>25mmHg, PCWP>15mmHg) in 5 of 7 cases.

CONCLUSIONS

We have developed a mathematical model capable of quantifying physiological parameters that reflect the severity of PH.

High-temporal velocity-encoded MRI for the assessment of left ventricular inflow propagation velocity: Comparison with color M-mode echocardiography

PURPOSE

To develop an alternative method for Vp-assessment using high-temporal velocity-encoded magnetic resonance imaging (VE-MRI). Left ventricular (LV) inflow propagation velocity (Vp) is considered a useful parameter in the complex assessment of LV diastolic function and is measured by Color M-mode echocardiography.

MATERIALS AND METHODS

A total of 43 patients diagnosed with ischemic heart failure (61 ± 11 years) and 22 healthy volunteers (29 ± 13 years) underwent Color M-mode echocardiography and VE-MRI to assess the inflow velocity through the mitral valve (mean interexamination time 14 days). Temporal resolution of VE-MRI was 10.8-11.8 msec. Local LV inflow velocity was sampled along a 4-cm line starting from the tip of the mitral leaflets and for consecutive sample points the point-in-time was assessed when local velocity exceeded 30 cm/s. From the position-time relation, Vp was calculated by both the difference quotient (Vp-MRI-DQ) as well as from linear regression (Vp-MRI-LR).

RESULTS

Good correlation was found between Vp-echo and both Vp-MRI-DQ (r = 0.83, P < 0.001) and Vp-MRI-LR (r = 0.84, P < 0.001). Vp-MRI showed a significant but small underestimation as compared to Vp measured by echocardiography (Vp-MRI-DQ: 5.5 ± 16.2 cm/s, P = 0.008; Vp-MRI-LR: 9.9 ± 15.2 cm/s, P < 0.001). Applying age-related cutoff values for Vp to identify LV impaired relaxation, kappa-agreement with echocardiography was 0.72 (P < 0.001) for Vp-MRI-DQ and 0.69 (P < 0.001) for Vp-MRI-LR.

CONCLUSION

High temporal VE-MRI represents a novel approach to assess Vp, showing good correlation with Color M-mode echocardiography. In healthy subjects and patients with ischemic heart failure, this new method demonstrated good agreement with echocardiography to identify LV impaired relaxation.

Age-specific changes in left ventricular diastolic function: a velocity-encoded magnetic resonance imaging study

OBJECTIVES

Our objectives were to assess the ability of phasecontrast MRI (PC-MRI) to detect sub-clinical age-related variations of left ventricular (LV) diastolic parameters and thus to provide age-related reference ranges currently available for echocardiography but not for MRI-PC, and to identify independent associates of such variations.

METHODS

We studied 100 healthy volunteers (age = 42 ± 15years, 50 females) who had MRI with simultaneous blood pressure measurements. LV mass and volumes were assessed. Semiautomated analysis of PC-MRI data provided: 1) early transmitral (Ef) and atrial (Af) peak filling flow-rates (ml/s) and filling volume (FV), 2) deceleration time (DT), isovolumic relaxation time (IVRT), and 3) early myocardial longitudinal (E') peak velocity.

RESULTS

MRI-PC diastolic parameters were reproducible as reflected by low coefficients of variations (ranged between 0.31 to 6.26 %). Peak myocardial velocity E' (r = -0.63, p < 0.0001) and flow-rate parameters were strongly and independently associated to age (Ef/Af:r = -0.63, DT:r = 0.46, IVRT:r = 0.44, Ef/FV:r = -0.55, Af/FV:r = 0.56, p < 0.0001). Furthermore, LV relaxation parameters (E', DT, IVRT), were independently associated to LV remodelling (LV mass/end-diastolic volume) and myocardial wall thickness (p < 0.01).

CONCLUSIONS

PC-MRI age-related reference ranges of diastolic parameters are provided. Such parameters might be useful for a fast, reproducible and reliable characterization of diastolic function in patients referred for clinical MRI exam

KEY POINTS

• MRI age-related reference values of left ventricular diastolic parameters are provided. • MRI diastolic parameters can characterise sub-clinical age-related variations in healthy individuals. • Diastolic function would complement cardiac MRI exam with currently neglected data. • Diastolic function would enhance MRI diagnostic value in cardiomyopathy and heartfailure.

Quantitative imaging biomarkers for the evaluation of cardiovascular complications in type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a prevalent condition in aged populations. Cardiovascular diseases are leading causes of death and disability in patients with T2DM. Traditional strategies for controlling the cardiovascular complications of diabetes primarily target a cluster of well-defined risk factors, such as hyperglycemia, lipid disorders and hypertension. However, there is controversy over some recent clinical trials aimed at evaluating efficacy of intensive treatments for T2DM. As a powerful tool for quantitative cardiovascular risk estimation, multi-disciplinary cardiovascular imaging have been applied to detect and quantify morphological and functional abnormalities in the cardiovascular system. Quantitative imaging biomarkers acquired with advanced imaging procedures are expected to provide new insights to stratify absolute cardiovascular risks and reduce the overall costs of health care for people with T2DM by facilitating the selection of optimal therapies. This review discusses principles of state-of-the-art cardiovascular imaging techniques and compares applications of those techniques in various clinical circumstances. Individuals measurements of cardiovascular disease burdens from multiple aspects, which are closely related to existing biomarkers and clinical outcomes, are recommended as promising candidates for quantitative imaging biomarkers to assess the responses of the cardiovascular system during diabetic regimens.

Comprehensive risk reduction in patients with atrial fibrillation: emerging diagnostic and therapeutic options--a report from the 3rd Atrial Fibrillation Competence NETwork/European Heart Rhythm Association consensus conference

While management of atrial fibrillation (AF) patients is improved by guideline-conform application of anticoagulant therapy, rate control, rhythm control, and therapy of accompanying heart disease, the morbidity and mortality associated with AF remain unacceptably high. This paper describes the proceedings of the 3rd Atrial Fibrillation NETwork (AFNET)/European Heart Rhythm Association (EHRA) consensus conference that convened over 60 scientists and representatives from industry to jointly discuss emerging therapeutic and diagnostic improvements to achieve better management of AF patients. The paper covers four chapters: (i) risk factors and risk markers for AF; (ii) pathophysiological classification of AF; (iii) relevance of monitored AF duration for AF-related outcomes; and (iv) perspectives and needs for implementing better antithrombotic therapy. Relevant published literature for each section is covered, and suggestions for the improvement of management in each area are put forward. Combined, the propositions formulate a perspective to implement comprehensive management in AF.

Ventricular dyssynchrony assessed by gated myocardial perfusion SPECT using a geometrical approach: a feasibility study

PURPOSE

Left ventricular dyssynchrony may predict response to cardiac resynchronization therapy and may well predict adverse cardiac events. Recently, a geometrical approach for dyssynchrony analysis of myocardial perfusion scintigraphy (MPS) was introduced. In this study the feasibility of this geometrical method to detect dyssynchrony was assessed in a population with a normal MPS and in patients with documented ventricular dyssynchrony.

METHODS

For the normal population 80 patients (40 men and 40 women) with normal perfusion (summed stress score ≤2 and summed rest score ≤2) and function (left ventricular ejection fraction 55-80%) on MPS were selected; 24 heart failure patients with proven dyssynchrony on MRI were selected for comparison. All patients underwent a 2-day stress/rest MPS protocol. Perfusion, function and dyssynchrony parameters were obtained by the Corridor4DM software package (Version 6.1).

RESULTS

For the normal population time to peak motion was 42.8 ± 5.1% RR cycle, SD of time to peak motion was 3.5 ± 1.4% RR cycle and bandwidth was 18.2 ± 6.0% RR cycle. No significant gender-related differences or differences between rest and post-stress acquisition were found for the dyssynchrony parameters. Discrepancies between the normal and abnormal populations were most profound for the mean wall motion (p value <0.001), SD of time to peak motion (p value <0.001) and bandwidth (p value <0.001).

CONCLUSION

It is feasible to quantify ventricular dyssynchrony in MPS using the geometrical approach as implemented by Corridor4DM.

Relation of left ventricular dyssynchrony measured by cardiac magnetic resonance tissue tracking in repaired tetralogy of fallot to ventricular tachycardia and death

The impact of left ventricular (LV) dyssynchrony on clinical outcomes in patients with tetralogy of Fallot (TOF) is unknown. The aim of this study was to test the hypothesis that LV dyssynchrony assessed by cardiac magnetic resonance (CMR)-derived tissue tracking in patients with repaired TOF is associated with ventricular tachycardia (VT) and death. Included patients had repaired TOF and CMR data from 2000 and 2008. Patients (n = 13) had histories of death or sustained VT. Control subjects (n = 26), with no death or VT, were matched by age at CMR and type of last surgical procedure. Demographic, clinical, and electrocardiographic data were recorded. CMR short-axis cine data were analyzed by tracking the motion of the endocardial border using commercial software. LV dyssynchrony was quantified as the maximum difference in time to peak radial displacement, circumferential strain, and radial strain among the 6 ventricular segments and the standard deviation of the times to peak value. There were no differences between groups in clinical, electrocardiographic, or demographic characteristics. Among CMR parameters, right ventricular volumes were higher and ejection fractions lower in the patient group. Indexes of LV dyssynchrony were higher in the patient group (e.g., maximum time difference of circumferential strain 94 vs 46 ms, p <0.001; standard deviation of circumferential strain 37.8 vs 20.3 ms, p <0.01). In a multivariate model including LV synchrony variables, the best outcome discriminator was maximum time difference to peak circumferential strain (p <0.01). In conclusion, tissue tracking applied to CMR images identifies indexes of LV synchrony associated with death and VT in patients with repaired TOF.

Cardiovascular MRI for the assessment of heart failure: focus on clinical management and prognosis

Cardiovascular MR (CMR) has an emerging role in the noninvasive diagnostic assessment of heart failure (HF). Different imaging sequences allow for a detailed assessment of cardiac morphology, function, myocardial perfusion, tissue characterization, and blood flow measurement. This article reviews the key applications of CMR in HF, with special focus on how CMR may influence the diagnostic and therapeutic approach of HF patients.

CMR for Assessment of Diastolic Function

Prevalence of heart failure with preserved left ventricular ejection fraction amounts to 50% of all cases with heart failure. Diagnosis assessment requires evidence of left ventricular diastolic dysfunction. Currently, echocardiography is the method of choice for diastolic function testing in clinical practice. Various applications are in use and recommended criteria are followed for classifying the severity of dysfunction. Cardiovascular magnetic resonance (CMR) offers a variety of alternative applications for evaluation of diastolic function, some superior to echocardiography in accuracy and reproducibility, some being complementary. In this article, the role of the available CMR applications for diastolic function testing in clinical practice and research is reviewed and compared to echocardiography.

Peak systolic mitral annulus velocity reflects the status of ventricular-arterial coupling-theoretical and experimental analyses

BACKGROUND

Peak systolic mitral annular velocity (S(m)) measured by tissue Doppler echocardiography has been recognized as an independent predictor of mortality in patients with heart failure and in the general population. However, the mechanical determinants of S(m) remain poorly defined.

METHODS

A theoretical model of S(m) was derived, which indicates that S(m) is affected positively by left ventricular (LV) contractility and preload and inversely by LV afterload and ejection time (EJT). In 16 anesthetized dogs, S(m), LV volume, and LV pressure were measured using sonomicrometry and catheter-tip micromanometry. LV contractility, preload, and afterload were indexed by the end-systolic pressure/volume ratio (E(es)'), end-diastolic volume (V(ed)), and effective arterial elastance (E(a)), respectively. LV contractility, loading conditions, and heart rate were varied over wide ranges, and a total of 76 data sets were obtained for S(m) (1.2-9.1 cm/sec), E(es)' (1.5-17.6 mm Hg/mL), V(ed) (11-99 mL), E(a) (3.6-58.4 mm Hg/mL), EJT (100-246 msec), heart rate (66-192 beats/min), and the ventricular-arterial coupling ratio (E(es)'/E(a); 0.2-3.0).

RESULTS

The theoretical model accurately predicted S(m) (R(2) = 0.79, P < .0001). By univariate analysis, S(m) was correlated significantly with E(es)' (R(2) = 0.64, P < .0001) and with the reciprocal of E(a) (R(2) = 0.49, P < .01). V(ed) and EJT did not affect S(m). E(es)'/E(a) was correlated strongly with S(m) (R(2) = 0.73, P < .0001). E(es)' and the reciprocal of E(a) were not correlated with each other.

CONCLUSIONS

LV contractility and afterload independently determine S(m). The effects of LV preload and EJT on S(m) might be small, even though they are theoretically associated with S(m). S(m) strongly reflects the status of ventricular-arterial coupling.

Automated left ventricular diastolic function evaluation from phase-contrast cardiovascular magnetic resonance and comparison with Doppler echocardiography

BACKGROUND

Early detection of diastolic dysfunction is crucial for patients with incipient heart failure. Although this evaluation could be performed from phase-contrast (PC) cardiovascular magnetic resonance (CMR) data, its usefulness in clinical routine is not yet established, mainly because the interpretation of such data remains mostly based on manual post-processing. Accordingly, our goal was to develop a robust process to automatically estimate velocity and flow rate-related diastolic parameters from PC-CMR data and to test the consistency of these parameters against echocardiography as well as their ability to characterize left ventricular (LV) diastolic dysfunction.

RESULTS

We studied 35 controls and 18 patients with severe aortic valve stenosis and preserved LV ejection fraction who had PC-CMR and Doppler echocardiography exams on the same day. PC-CMR mitral flow and myocardial velocity data were analyzed using custom software for semi-automated extraction of diastolic parameters. Inter-operator reproducibility of flow pattern segmentation and functional parameters was assessed on a sub-group of 30 subjects. The mean percentage of overlap between the transmitral flow segmentations performed by two independent operators was 99.7 ± 1.6%, resulting in a small variability (<1.96 ± 2.95%) in functional parameter measurement. For maximal myocardial longitudinal velocities, the inter-operator variability was 4.25 ± 5.89%. The MR diastolic parameters varied significantly in patients as opposed to controls (p < 0.0002). Both velocity and flow rate diastolic parameters were consistent with echocardiographic values (r > 0.71) and receiver operating characteristic (ROC) analysis revealed their ability to separate patients from controls, with sensitivity > 0.80, specificity > 0.80 and accuracy > 0.85. Slight superiority in terms of correlation with echocardiography (r = 0.81) and accuracy to detect LV abnormalities (sensitivity > 0.83, specificity > 0.91 and accuracy > 0.89) was found for the PC-CMR flow-rate related parameters.

CONCLUSIONS

A fast and reproducible technique for flow and myocardial PC-CMR data analysis was successfully used on controls and patients to extract consistent velocity-related diastolic parameters, as well as flow rate-related parameters. This technique provides a valuable addition to established CMR tools in the evaluation and the management of patients with diastolic dysfunction.

Statin therapy decreases myocardial function as evaluated via strain imaging

OBJECTIVES

The purpose of this study was to evaluate the effects of statin therapy on myocardial function as measured with echocardiography with tissue Doppler imaging (TDI) and strain imaging (SI) independent of its lipid-lowering effect.

BACKGROUND

Statin use is known to improve outcomes in the primary and secondary prevention of ischemic heart disease, but their use is also associated with myopathy, muscle weakness and in rare cases, rhabdomyolysis. We sought to evaluate whether TDI and SI is able to identify changes in myocardial function associated with statin use.

METHODS

Myocardial function was evaluated in 28 patients via echocardiography with TDI and SI. We identified 12 patients (5 females) without overt cardiovascular disease (including hypertension, smoking, and diabetes) that were on statin therapy and compared their echocardiographic findings with 16 (12 females) age, sex, and cholesterol-profile-matched controls. Tissue Doppler imaging parameters of diastolic (E(')/A(') and E/E(')) and systolic (S') function were measured. Regional systolic function was obtained by SI in 4-chamber, 2-chamber, long axis, and average global views.

RESULTS

There was no significant difference in myocardial function as measured by Doppler and minor differences as measured via TDI among the 2 groups. There was significantly better function noted with SI in the control group vs the statin group in the 4-chamber (-19.05% +/- 2.45% vs -16.47% +/- 2.37% P = 0.009), 2-chamber (-20.30% +/- 2.66% vs -17.45% +/- 4.29% P = 0.03), long axis (-17.63% +/- 3.79% vs -13.83% +/- 3.74% P = 0.01), and average global (-19.0% +/- 2.07% vs -15.91% +/- 2.81% P = 0.004) views.

CONCLUSION

Statin therapy is associated with decreased myocardial function as evaluated with SI.

Applicability of body surface potential map in computerized optimization of biventricular pacing

Biventricular pacing (BVP) could be improved by identifying the patient-specific optimal electrode positions. Body surface potential map (BSPM) is a non-invasive technique for obtaining the electrophysiology and pathology of a patient. The study proposes the use of BSPM as input for an automated non-invasive strategy based on a personalized computer model of the heart, to identify the patient pathology and specific optimal treatment with BVP devices. The anatomy of a patient suffering from left bundle branch block and myocardial infarction is extracted from a series of MR data sets. The clinical measurements of BSPM are used to parameterize the computer model of the heart to represent the individual pathology. Cardiac electrophysiology is simulated with ten Tusscher cell model and excitation propagation is calculated with adaptive cellular automaton, at physiological and pathological conduction levels. The optimal electrode configurations are identified by evaluating the QRS error between healthy and pathology case with/without pacing. Afterwards, the simulated ECGs for optimal pacing are compared to the post-implantation clinically measured ECGs. Both simulation and clinical optimization methods identified the right ventricular (RV) apex and the LV posterolateral regions as being the optimal electrode configuration for the patient. The QRS duration is reduced both in measured and simulated ECG after implantation with 20 and 14%, respectively. The optimized electrode positions found by simulation are comparable to the ones used in hospital. The similarity in QRS duration reduction between measured and simulated ECG signals indicates the success of the method. The computer model presented in this work is a suitable tool to investigate individual pathologies. The personalized model could assist therapy planning of BVP in patients with congestive heart failure. The proposed method could be used as prototype for further clinically oriented investigations of computerized optimization of biventricular pacing.