Speckle-tracking analysis of myocardial deformation in correlation to age in healthy horses

An effect of aging on cardiac morphology and function has been shown in humans. In horses, cardiac wall motion analysis using two-dimensional speckle tracking (2D-ST) has not yet been reported. Our study included 57 horses of different warmblood breeds between 3 and 30 years old. Age had a significant influence on left ventricular free wall (LVFW) systolic strain rate (p ≤ 0.05) and early diastolic relaxation (p ≤ 0.01). In the interventricular septum (IVS), systolic (p ≤ 0.01) and late diastolic (p ≤ 0.05) contraction velocities also increased with age. In our study, 2D-ST revealed important information on myocardial function, which was most evident in the LVFW, where measurements were highly reproducible. Aging seems to be associated with structural changes within the myocardium and with decreasing contraction capacity in old animals. These physiological, age-related processes should be considered when performing cardiac wall motion analysis of the 2D-ST results for the LVFW and IVS in horses

Unravelling the role of the left and right ventricles in pulmonary arterial hypertension: patient and small animal cardiac MRI studies

The definite hemodynamic diagnosis of pulmonary hypertension (PH) requires direct measurement of the pulmonary artery pressure by right heart catheterisation. As right heart catheterisation is an invasive test with a small risk of associated morbidity and mortality, diagnostic algorithms have been devised that combines clinical history and examination, cardio- respiratory assessment by non-imaging techniques and subsequently imaging techniques in patients suspected of having PH. The aim of these initial investigations is to establish a tentative diagnosis of PH, help identify the underlying aetiology and to provide information regarding disease severity and determine response to treatment. Although PH is a disease of the pulmonary vasculature, it is the subsequent right ventricular (RV) failure that is the main cause of morbidity and mortality in PH patient. Thus, RV is the most widely studied of the chambers in PH, however focus has started to move to the left ventricle (LV). Although a disease of the pulmonary circulation and the RV, there is now evidence demonstrating LV abnormalities in PH. Further to this, the atrial chambers offer valuable information when measuring cardiac function as well as in identifying the aetiology of PH. Small animal (rodent) models are increasingly used to identify pathophysiology as well as therapies for PH with the intention of translating the findings to humans. Accurate monitoring of disease in rodents with emphasis on ventricular function and the ability to monitor the disease state without killing the animal is needed

Effects of high-normal and mildly increased arterial blood pressure on right ventricular function: application of new echocardiographic techniques

Purpose: To analyze the relationship between increasing systemic blood pressure and right ventricular function by means of Tissue-Doppler Imaging (TDI) and Two-dimesional Strain echocardiographic techniques. Subjects and methods: Ninety-eight never-treated, nonobese patients with blood pressure values varying from the optimal to the mild hypertensive range were recruited. Peak early (Em) and late (Am) diastolic and systolic (Sm) velocities were recorded at the tricuspid and mitral annuli by TDI. Longitudinal peak strain and strain rate (SR) were sampled by speckle-tracking methodology at the right ventricle (RV) free wall and interventricular septum (IVS) and RV and left ventricular (LV) structure and function were evaluated by conventional echo-Doppler sonography. Insulin sensitivity was tested by homeostasis model assessment (HOMA) index. Data were analyzed by 24-h systolic BP (SBP) (cut-offs 117 and 130 mmHg), thus partitioning an optimal BP from an intermediate high-normal and an upper mildly increased BP stratum. Results: Em decreased in the mid-third and decelerated further in association with reduced Sm in the upper BP tertile; both correlated negatively to septal thickness and positively to homologous TDI-derived LV indices. RV peak systolic strain and early diastolic SR decreased in the mid-BP third without further changes in the upper tertile. IVS thickened gradedly by increasing systemic 24-h SBP; posterior wall remodelled to a lesser extent and poorly related to BP load and LV mass index did not change. RV and IVS systolic and diastolic strain indices associated inversely with increasing septal thickness. RV and LV indices of global ventricular function, estimated pulmonary pressure, HOMA did not differ by systemic BP. Conclusion: TDI and 2D-strain echocardiography showed a RV diastolic and systolic function impairment in response to slightly increased systemic BP. The process paralleled homologous changes at the LV side and was driven by interventricular septum remodeling, perhaps as a reflection of its role in RV function and biventricular interdependence. Insulin sensitivity seemed to play no relevant role

Use of tissue Doppler imaging and two-dimensional speckle tracking for quantification of left ventricular function in horses

In horses with cardiac disease or poor performance, echocardiography is an essential tool for non-invasive evaluation of myocardial function. Left ventricular (LV) function is usually quantified by calculating fractional shortening (FS). Tissue Doppler imaging (TDI) and two-dimensional speckle tracking (2DST) are two echocardiographic techniques that might provide a more extensive quantification of left ventricular function. TDI measures myocardial velocities based on the Doppler principle. Myocardial deformation can be calculated from the velocity gradient between the endo- and epicardium. The total amount of wall deformation is described as strain (%), the rate of deformation as strain rate (s-1). Using 2DST, acoustic speckle patterns which are unique for each myocardial region are tracked in the two dimensions of the ultrasound image. As a result, longitudinal and circumferential shortening can be measured in addition to radial wall thickening. The aim of this study was to evaluate the use of TDI and 2DST for quantification of LV function in horses. First, the feasibility and reproducibility of TDI and 2DST measurements were described in ten healthy trotter horses. Using a modified four-chamber view, 2DST allowed quantification of global and segmental longitudinal LV velocity, displacement, strain rate and strain. Using short-axis images acquired at chordal and papillary muscle level, circumferential and radial LV function could be assessed by 2DST. Using TDI, radial velocity, strain rate and strain measurements were feasible from left and right parasternal short-axis views at chordal and papillary muscle level. The high frame rate allowed accurate measurements of systolic and diastolic time intervals. Next, the influence of the atrioventricular (AV) delay on mitral valve closure and LV peak velocity and acceleration during isovolumic contraction was investigated. This study demonstrated that AV interaction should be kept in mind when using peak pre-ejectional velocity and acceleration as parameters of LV contractility. The clinical use of TDI and 2DST was evaluated in horses with myocardial damage caused by an accidental ionophore intoxication on a farm in Belgium with eighty-one horses. Twenty horses were included in the echocardiographic study as they showed signs of myocardial damage. These horses showed abnormal TDI, 2DST and FS measurements, indicating impaired LV function. In a horse with myocardial fibrosis, TDI and 2DST could detect regional alterations of myocardial function caused by the predominant presence of fibrosis in the interventricular septum. Over all horses, TDI measurements, SL, SR at chordal level and FS correlated significantly with maximal cTnI. Over all examinations, TDI and 2DST measurements correlated well with FS. The ability of TDI and 2DST to detect myocardial dysfunction in horses with normal FS was investigated in twelve horses with atypical myopathy (AM). AM is an acute, highly fatal rhabdomyolysis in grazing horses. Eleven horses with AM had elevated cTnI concentrations and ten horses ventricular premature depolarizations (VPDs). All horses presented a prolonged corrected QT (QTcf) interval and an abnormal LV wall motion pattern. FS was normal in all horses. TDI measurements revealed abnormal LV relaxation with prolonged contraction duration, increased isovolumic relaxation time and decreased ratio of early to late diastolic (E/A) LV radial velocities. Decreased LV global longitudinal strain and increased mechanical dispersion between myocardial segments could be detected by 2DST. One of four surviving horses still showed VPDs and a mildly prolonged QTcf after ten weeks follow-up, although the wall motion abnormality had disappeared. In conclusion, TDI and 2DST can be considered complimentary for the comprehensive quantification of LV function. In the future, TDI and 2DST might be applied for detection of subclinical myocardial dysfunction in horses with valvular disease, for evaluating the effect of training or for quantification of right ventricular and atrial function

Echocardiography

The book "Echocardiography - New Techniques" brings worldwide contributions from highly acclaimed clinical and imaging science investigators, and representatives from academic medical centers. Each chapter is designed and written to be accessible to those with a basic knowledge of echocardiography. Additionally, the chapters are meant to be stimulating and educational to the experts and investigators in the field of echocardiography. This book is aimed primarily at cardiology fellows on their basic echocardiography rotation, fellows in general internal medicine, radiology and emergency medicine, and experts in the arena of echocardiography. Over the last few decades, the rate of technological advancements has developed dramatically, resulting in new techniques and improved echocardiographic imaging. The authors of this book focused on presenting the most advanced techniques useful in today's research and in daily clinical practice. These advanced techniques are utilized in the detection of different cardiac pathologies in patients, in contributing to their clinical decision, as well as follow-up and outcome predictions. In addition to the advanced techniques covered, this book expounds upon several special pathologies with respect to the functions of echocardiography

Quantification of left ventricular longitudinal strain, strain rate, velocity and displacement in healthy horses by 2-dimensional speckle tracking

Background: The quantification of equine left ventricular (LV) function is generally limited to short-axis M-mode measurements. However, LV deformation is 3-dimensional (3D) and consists of longitudinal shortening, circumferential shortening, and radial thickening. In human medicine, longitudinal motion is the best marker of subtle myocardial dysfunction. Objectives: To evaluate the feasibility and reliability of 2-dimensional speckle tracking (2DST) for quantifying equine LV longitudinal function. Animals: Ten healthy untrained trotter horses; 9.6 +/- 4.4 years; 509 +/- 58 kg. Methods : Prospective study. Repeated echocardiographic examinations were performed by 2 observers from a modified 4-chamber view. Global, segmental, and averaged peak values and timing of longitudinal strain (SL), strain rate (SrL), velocity (VL), and displacement (DL) were measured in 4 LV wall segments. The inter- and intraobserver within- and between-day variability was assessed by calculating the coefficients of variation for repeated measurements. Results: 2DST analysis was feasible in each exam. The variability of peak systolic values and peak timing was low to moderate, whereas peak diastolic values showed a higher variability. Significant segmental differences were demonstrated. DL and VL presented a prominent base-to-midwall gradient. SL and SrL values were similar in all segments except the basal septal segment, which showed a significantly lower peak SL occurring about 60 ms later compared with the other segments. Conclusions and Clinical Importance 2DST is a reliable technique for measuring systolic LV longitudinal motion in healthy horses. This study provides preliminary reference values, which can be used when evaluating the technique in a clinical setting

Bi-Ventricular Myocardial Performance in Heart Failure: A New Approach to Evaluate Interventricular Dyssynchrony

Aims: Patients with heart failure (HF) exhibit ventricular dyssynchrony with negative effects on ventricular systolic and diastolic performance and poor prognosis. There is no consensus about the best approach for estimating the dyssynchrony and for selecting candidates for resynchronization therapy (CRT). We sought to evaluate whether Myocardial Performance Index (MPI), calculated as differences between left and right ventricle (LV, RV), ΔMPI, represents a marker of interventricular dyssynchrony. Methods: The study included 40 patients (22 males, 18 females, mean age 71±13) with NYHA functional class II-III, chronic heart failure (77% ischaemic), in optimal drug therapy for at least three months. All patients underwent a complete two-dimensional and Tissue Doppler Echocardiography (TDE), including an assessment of MPI in both ventricles. Results: Significant correlations were found between ΔMPI and QRS (r = 0.41, p < 0.001), with NYHA (r = 0.66, p < 0.001), with SPWMD (r = 0.32, p < 0.05), with LV ejection fraction (r = -0.32, p < 0.05), with Spv wave at the septal site of LV (r = -0.32, p < 0.05), and with IVMD (r = 0.44, p < 0.001). Ten patients have been re-evaluated six months after CRT implantation, and ΔMPI significantly correlated with the difference between basal LVEF and six months after CRT implantation (r = 0.43, p < 0.04). Conclusion: The ΔMPI could represent an integrative marker of interventricular dyssynchrony and could be considered as a new parameter in the patient selection process to be undergone CRT

Myocardial strain analysis with high temporal resolution MRI tagging: extended 3D motion tracking in normal and LBBB hearts

Tese de doutoramento em Biofísica, apresentada à Universidade de Lisboa através da Faculdade de Ciências, 200

The cardiac torsion as a sensitive index of heart pathology: A model study.

The torsional behaviour of the heart (i.e. the mutual rotation of the cardiac base and apex) was proved to be sensitive to alterations of some cardiovascular parameters, i.e. preload, afterload and contractility. Moreover, pathologies which affect the fibers architecture and cardiac geometry were proved to alter the cardiac torsion pattern. For these reasons, cardiac torsion represents a sensitive index of ventricular performance. The aim of this work is to provide further insight into physiological and pathological alterations of the cardiac torsion by means of computational analyses, combining a structural model of the two ventricles with simple lumped parameter models of both the systemic and the pulmonary circulations. Starting from diagnostic images, a 3D anatomy based geometry of the two ventricles was reconstructed. The myocytes orientation in the ventricles was assigned according to literature data and the myocardium was modelled as an anisotropic hyperelastic material. Both the active and the passive phases of the cardiac cycle were modelled, and different clinical conditions were simulated. The results in terms of alterations of the cardiac torsion in the presence of pathologies are in agreement with experimental literature data. The use of a computational approach allowed the investigation of the stresses and strains in the ventricular wall as well as of the global hemodynamic parameters in the presence of the considered pathologies. Furthermore, the model outcomes highlight how for specific pathological conditions, an altered torsional pattern of the ventricles can be present, encouraging the use of the ventricular torsion in the clinical practice.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.jmbbm.2015.10.00