Ultrasonic strain/strain rate imaging—a new clinical tool to evaluate the transplanted heart

Left ventricular adaptation following orthotopic heart transplantation in children: A speckle tracking echocardiographic imaging study

BACKGROUND

Evolution of left ventricle (LV) function in the pediatric OHT population has not been well described. Our hypothesis was that, in children following OHT without any rejection, there would be progressive normalization of LV size and function over 2 years.

METHODS

LV function was evaluated using STE and conventional echo parameters at five time points in pediatric OHT patients without any rejection in the first 2 years following OHT and normal controls. LV global peak systolic longitudinal strain (LVPLS) and strain rate, LV peak systolic radial and circumferential strain (LVRS and LVCS), and strain rate were analyzed.

RESULTS

We had twenty two patients with median age at OHT of 1.27 years ( IQR 0.19, 5.6 years). The LVPLS (mean ± SD) was abnormal in the post-OHT echocardiograms at 1 week (-12.4 ± 3.7) and 1 month (-13.9 ± 3.7) and significantly improved at 6 months (-15.8 ± 3.2), 1 year (-15.7 ± 3.1), and 2 years (-17.8 ± 2.8). However, LVPLS remained below the normal group even at 2 years following OHT (-21.3 ± 1.76).

CONCLUSION

In children following OHT, despite the absence of rejection, strain values are significantly impaired in the initial months, improve progressively over the first 2 years but remain abnormal compared with healthy controls.

Decline in ventricular function as a result of general anesthesia in pediatric heart transplant recipients

Echocardiography is frequently performed under anesthesia during procedures such as cardiac catheterization with EMB in pediatric HTx recipients. Anesthetic agents may depress ventricular function, resulting in concern for rejection. The aim of this study was to compare ventricular function as measured by echocardiography before and during GA in 17 pediatric HTx recipients. Nearly all markers of ventricular systolic function were significantly decreased under GA, including EF (-4.2% ±1.2, P < .01) and RV FAC (-0.05 ± 0.02, P = .04). Subjects in the first post-transplant year (n = 9) trended toward a more significant decrease in EF vs those beyond the first post-transplant year (n = 8; -6.0% ±1.2 vs -2.1 ± 2.0, P = .1). This information quantifies a decline in biventricular function that should be expected in pediatric HTx recipients while under GA and can assist the transplant clinician in avoiding unnecessary treatment of transient GA-induced ventricular dysfunction.

Evaluation of Acute Rejection by Measuring Strain and Strain Rate in Children With Heart Transplant: A Preliminary Report

OBJECTIVES

Asymptomatic rejection after heart transplant is difficult to detect by noninvasive methods. The present study investigated the efficacy of echocardiographic strain and the strain rate imaging method in detecting rejection after pediatric heart transplant.

MATERIALS AND METHODS

Fourteen pediatric patients with heart transplant were examined both with endomyocardial biopsy and strain imaging. Patients were divided into 2 groups: group 1 included patients with rejection, and group 2 included patients without rejection. Patients underwent endomyocardial biopsy at regular intervals. Regional systolic function was evaluated by longitudinal myocardial peak systolic values of strain and of strain rate. Differences between the 2 groups were assessed with unpaired t test or Mann-Whitney U test.

RESULTS

Acute rejection was detected in 7 patients (4 were female patients). Cardiac diagnosis was restrictive cardiomyopathy in 3 patients, dilated cardiomyopathy in 3 patients, and complex congenital heart disease in 1 patient. After heart transplant, 6 patients had rejection once and 1 patient had rejection twice. Evaluation of biopsy samples revealed grade IB rejection in all patients in group 1. Systolic functions of the 6 patients were determined as normal in standard echocardiographic examination. There were no significant differences in deformation and deformation rates between group 1 and 2 except in midseptal region (P < .05).

CONCLUSIONS

One of the most significant complications in patients with heart transplant is rejection. Our results suggested that myocardial strain imaging may be valuable in defining low-grade rejection.

Strain and strain rate imaging using speckle tracking in acute allograft rejection in children with heart transplantation

Acute allograft rejection is a major cause of morbidity and mortality following heart transplantation. There is no reliable noninvasive test to diagnose rejection. We aimed to investigate the accuracy of strain by speckle tracking echocardiography in the detection of acute rejection. We identified acute rejection episodes in patients followed at a single transplant center. Data were collected at baseline, during rejection and two follow-up points. Peak systolic radial and circumferential strain at the level of papillary muscles and peak systolic longitudinal strain from apical four-chamber view were analyzed offline. ANOVA was used for comparison between groups. p value ≤0.05 was considered significant. Fifteen rejection episodes were identified. There were no differences in the fractional shortening, LV posterior wall thickness, E/A, septal E/E', septal S', lateral E/E', lateral S', or MPI during rejection, compared to baseline. There was a significant increase in the LV mass during a rejection episode (47.5 vs. 34.4 g/ht(2.7) [p = 0.03]). The peak systolic radial strain (18.3 vs. 26.5; p = 0.03), longitudinal strain (-11.7 vs. -14.6; p = 0.05), and circumferential strain (-14.4 vs. -21.7; p = 0.05) declined significantly during rejection. In conclusion, peak systolic radial, longitudinal and circumferential strain decline and LV mass increases during an episode of rejection.

Cardiac mechanics in heart transplant recipients with and without transplant vasculopathy

Evaluation of cardiac mechanics in heart transplant recipients (HTR) is of paramount importance. Assessment of strain through echocardiography is suited to describe cardiac function and might allow characterizing patients with and without transplant vasculopathy (TVP) a risk factor of impaired organ function and rejection. For this study 41 HTR immediately after and 1-3 years after transplantation were examined in a retrospective approach with 2-dimensional speckle tracking echocardiography to assess longitudinal, radial and circumferential strain and strain rate. The cohort consists of 33 men and 8 women with a median age of 54 years (1st, 3rd; 45.7, 65.3) with seven cases diagnosed with TVP during follow-up, as diagnosed by coronary angiography. The overall cohort showed an improvement of global longitudinal strain from baseline to 1 and 3 years with -14.2% (-16.9, -12.3%) to -16.1% (-17.5, -14.3%) and -16.7% (-18, -13.7%), p = 0.036. For patients developing TVP, global longitudinal strain was not different from baseline up to the maximum of 3 years -16.6% (-16.7-13.8%) to -16.4% (-17.3, -14.7%) and -17.6% (-18.7, -16.9%) with p = 0.21. Radial strain and torsion showed a trend to decrease after transplantation with time. Circumferential strain remained stable in HTR but decreased in subjects with TVP. Longitudinal Strain and strain rate showed no relevant changes in HTR with and without TVP. Radial strain and torsion declined in HTR as well as TVP patients with time. Speckle tracking imaging is useful to assess organ function in HTR, however coronary angiography is still needed to rule out TVP.

Effects of Paclitaxel and Carboplatin combination on mechanical myocardial and microvascular functions: a transthoracic Doppler echocardiography and two-dimensional strain imaging study

AIM

Paclitaxel and carboplatin are frequently used chemotherapy drugs in the treatment of gynecologic malignancies. Little is known about their effects on left ventricular mechanical and coronary microvascular functions.

METHODS

Thirty consecutive patients were prospectively enrolled. Patients underwent transthoracic echocardiography (TTE) before and after chemotherapy, to evaluate left ventricular mechanical functions and coronary flow reserve (CFR). A comprehensive TTE, tissue Doppler and two-dimensional (2D) strain imaging were performed and coronary flow velocity was measured at baseline and after dipyridamole infusion. CFR was calculated as the ratio of hyperemic to baseline diastolic peak flow velocities. Mitral annular velocities by tissue Doppler, peak strain, and systolic strain rate by velocity vector imaging (VVI) were measured. Baseline measurements were compared with healthy controls (n = 26).

RESULTS

No patient developed heart failure (HF) symptoms, no significant change occurred in left ventricular ejection fraction or cardiac output and no significant difference was observed in CFR after chemotherapy. Baseline mean longitudinal peak strain and systolic stain rate were similar between patients and controls: -17.5 ± 2.6% versus -17.6 ± 2.2% (P = NS) and -1.04 ± 0.14/sec versus -1.05 ± 0.12/sec (P = NS). Peak strain and systolic strain rate decreased significantly after chemotherapy (from -17.5 ± 2.6% to -16.2 ± 2.5%, P < 0.02; and from -1.05 ± 0.12/sec to -0.96 ± 0.11/sec, P = 0.01, respectively). However, mean longitudinal velocity did not change significantly.

CONCLUSION

Paclitaxel and carboplatin combination did not impair CFR; however, this chemotherapy combination could induce subtle impairment in myocardial mechanical function which can be detected by advanced deformation imaging techniques rather than by tissue Doppler imaging or conventional 2D and Doppler echocardiography.

Left ventricular systolic strain of the cardiac allograft evaluated with three-dimensional speckle tracking echocardiography

Three-dimensional speckle tracking echocardiography was employed to evaluate the changes of left ventricular systolic strain in 23 heart transplant recipients at 1st, 3rd, 6th and 12th month after heart transplantation, and 23 healthy subjects served as controls. The three-dimensional full-volume echocardiographic images of left ventricle were recorded and then were analyzed using EchoPAC software. The strain curves and peak systolic strain values for each segment and overall left ventricular wall were obtained. Left ventricular global peak longitudinal strain (GPSL), global peak radial strain (GPSR), global peak circumferential strain (GPSC) and global peak area strain (GPSA) were measured and then statistically analyzed. There were no significant differences in left ventricular ejection fraction (LVEF) and cardiac output (CO) between heart transplant recipients and controls. The GPSL in heart transplant recipients at 1st month after surgery was significantly lower than that in controls, but close to the normal value at 3rd month after surgery and later. The GPSC, GPSA and GPSR were significantly lower in heart transplant recipients at 1st, 3rd, 6th and 12th month after surgery than those in controls. It is suggested that three-dimensional speckle tracking echocardiography can be used for monitoring changes of left ventricular systolic strains and evaluating left ventricular systolic function in cardiac allograft.

Cold ischaemic time and time after transplantation alter segmental myocardial velocities after heart transplantation

OBJECTIVES

The aim of this study was to investigate changes in segmental, three-directional left ventricular (LV) velocities in patients after heart transplantation (Tx).

METHODS

Magnetic resonance tissue phase mapping was used to assess myocardial velocities in patients after Tx (n = 27) with normal LV ejection fraction (63 ± 5%) and those without signs of rejection. Regional wall motion and dyssynchrony were analysed in relation to cold ischaemic time (150 ± 57 min, median = 154 min), age of the donor heart (35 ± 13 years, median = 29 years), time after transplantation (32 ± 26 months, median = 31 months) and global LV morphology and function.

RESULTS

Segmental myocardial velocities were significantly altered in patients with cold ischaemic times >155 min resulting in an increase in peak systolic radial velocities (2 of 16 segments, P = 0.03-0.04) and reduced segmental diastolic long-axis velocities (5 of 16 segments, P = 0.01-0.04). Time after transplantation (n = 8 patients <12 months after Tx vs n = 19 >12 months) had a significant influence on systolic radial velocities (increased in 2 of 16 segments, P = 0.01-0.04) and diastolic long-axis velocities (reduced in 5 of 16 segments, P = 0.02-0.04). Correlation analysis and multiple regression revealed significant relationships of cold ischaemic time (R = -0.384, P = 0.048), the donor heart's age (β= 0.9, P = 0.01) and time from transplantation (β= -0.36, P = 0.03) with long-axis diastolic dyssynchrony.

CONCLUSIONS

Time after transplantation and cold ischaemic time strongly affect segmental systolic and diastolic motion in patients after Tx. The understanding of alterations in regional LV motion in the transplanted heart under stable conditions is essential in order to utilize this methodology in the future as a potentially non-invasive means of diagnosing transplant rejection.

One year of high-intensity interval training improves exercise capacity, but not left ventricular function in stable heart transplant recipients: a randomised controlled trial

BACKGROUND

Heart transplant recipients have lower exercise capacity and impaired cardiac function compared with the normal population. High-intensity interval training (HIIT) improves exercise capacity and cardiac function in patients with heart failure and hypertension, but the effect on cardiac function in stable heart transplant recipients is not known. Thus, we investigated whether HIIT improved cardiac function and exercise capacity in stable heart transplant recipients by use of comprehensive rest- and exercise-echocardiography and cardiopulmonary exercise testing.

DESIGN AND METHODS

Fifty-two clinically stable heart transplant recipients were randomised either to HIIT (4 × 4 minutes at 85-95% of peak heart rate three times per week for eight weeks) or to control. Three such eight-week periods were distributed throughout one year. Echocardiography (rest and submaximal exercise) and cardiopulmonary exercise testing were performed at baseline and follow-up.

RESULTS

One year of HIIT increased VO 2peak from 27.7 ± 5.5 at baseline to 30.9 ± 5.0 ml/kg/min at follow-up, while the control group remained unchanged (28.5 ± 7.0 vs. 28.0 ± 6.7 ml/kg per min, p < 0.001 for difference between the groups). Systolic and diastolic left ventricular functions at rest and during exercise were generally unchanged by HIIT.

CONCLUSIONS

Whereas HIIT is feasible in heart transplant recipients and effectively improves exercise capacity, it does not alter cardiac systolic and diastolic function significantly. Thus, the observed augmentation in exercise capacity is best explained by extra-cardiac adaptive mechanisms.

Longitudinal myocardial deformation is selectively decreased after pediatric cardiac transplantation: a comparison of children 1 year after transplantation with normal subjects using velocity vector imaging

The transplanted heart experiences numerous hemodynamic changes during and after cardiac transplantation. This study sought to evaluate the left ventricular myocardial mechanics in the pediatric heart transplant population using Velocity Vector Imaging (VVI). This study retrospectively evaluated 28 heart transplant recipients by echocardiography 12 months after transplantation. Echocardiograms from 28 age- and gender-matched subjects were used as a control group. Peak global longitudinal and circumferential left ventricular strain, systolic strain rate, and diastolic strain rate were obtained. Student's t tests were used to assess differences between the two groups (defined as p ≤ 0.05). The peak global left ventricular longitudinal strain was lower in the transplant group (17.21%) than in the control group (22.14%). The transplant and control groups did not differ significantly in terms of their peak global circumferential strain (20.28% vs. 20.79%, respectively). Similar results were observed for longitudinal and circumferential systolic and diastolic strain rates. The transplant patients showed statistically significant reductions in all peak global longitudinal measures compared with those of the control subjects. Circumferential myocardial deformation appears to be preserved in transplant recipients. This could suggest evidence of ischemia given the known myocardial fiber arrangement of longitudinal fibers toward the endocardial surface, which is also more distal in the coronary arterioles.

Strain-encoded cardiac magnetic resonance for the evaluation of chronic allograft vasculopathy in transplant recipients

The aim of our study was to investigate the ability of Strain-Encoded magnetic resonance imaging (MRI) to detect cardiac allograft vasculopathy (CAV) in heart transplantation (HTx)-recipients. In consecutive subjects (n = 69), who underwent cardiac catheterization, MRI was performed for quantification of myocardial strain and perfusion reserve. Based on angiographic findings subjects were classified: group A including patients with normal vessels; group B, patients with stenosis <50%; and group C, patients with severe CAV (stenosis >or= 50%). Significant correlations were observed between myocardial perfusion reserve with peak systolic strain (r =-0.53, p < 0.001) and with mean diastolic strain rate (r = 0.82, p < 0.001). Peak systolic strain and strain rate were significantly reduced only in group C, while mean diastolic strain rate and myocardial perfusion reserve were already reduced in group B and A. Myocardial perfusion reserve and mean diastolic strain rate had higher accuracy for the detection of CAV (AUC = 0.95, 95% CI = 0.87-0.99 and AUC = 0.93, 95% CI = 0.84-0.98, respectively) and followed peak systolic strain and strain rate (AUC = 0.80, 95% CI = 0.69-0.89 and AUC = 0.78, 95% CI = 0.67-0.87, respectively). Besides the quantification of myocardial perfusion, the estimation of the diastolic strain rate is a useful parameter for CAV assessment. In combination with the clinical evaluation, these parameters may be effective tools for the routine surveillance of HTx-recipients.

Usefulness and limitations of transthoracic echocardiography in heart transplantation recipients

Transthoracic echocardiography is a primary non-invasive modality for investigation of heart transplant recipients. It is a versatile tool which provides comprehensive information about cardiac structure and function. Echocardiographic examinations can be easily performed at the bedside and serially repeated without any patient's discomfort. This review highlights the usefulness of Doppler echocardiography in the assessment of left ventricular and right ventricular systolic and diastolic function, of left ventricular mass, valvular heart disease, pulmonary arterial hypertension and pericardial effusion in heart transplant recipients. The main experiences performed by either standard Doppler echocardiography and new high-tech ultrasound technologies are summarised, pointing out advantages and limitations of the described techniques in diagnosing acute allograft rejection and cardiac graft vasculopathy. Despite the sustained efforts of echocardiographic technique in predicting the biopsy state, endocardial myocardial biopsies are still regarded as the gold standard for detection of acute allograft rejection. Conversely, stress echocardiography is able to identify accurately cardiac graft vasculopathy and has a recognised prognostic in this clinical setting. A normal stress-echo justifies postponement of invasive studies. Another use of transthoracic echocardiography is the monitorisation and the visualisation of the catheter during the performance of endomyocardial biopsy. Bedside stress echocardiography is even useful to select appropriately heart donors with brain death. The ultrasound monitoring is simple and effective for monitoring a safe performance of biopsy procedures.

Tissue Doppler Assessment of Longitudinal Right and Left Ventricular Strain and Strain Rate in Pulmonary Artery Hypertension

Tissue Doppler imaging (TDI) in 38 adult patients with pulmonary artery hypertension of varied etiology and normal left ventricular systolic function by two-dimensional transthoracic echocardiography showed significantly reduced peak systolic strain (SS) in all three segments of left ventricular free wall and ventricular septum and two of three segments of right ventricular free wall when compared to 29 adults with no clinical or echocardiographic evidence of heart disease and normal left and right ventricular systolic function. A similar reduction in peak diastolic strain (DS) was also noted in all three segments of left ventricular free wall and ventricular septum and one of three segments of right ventricular free wall. This reduction in strain indices in patients with pulmonary hypertension was noted irrespective of whether right ventricular systolic function was normal or reduced as assessed by two-dimensional transthoracic echocardiography. SS and DS rates also showed reductions in patients with pulmonary artery hypertension. Our study shows the potential value of TDI indices in identifying reduced regional left ventricular systolic and diastolic longitudinal function in patients with pulmonary artery hypertension and normal left ventricular systolic function by two-dimensional transthoracic echocardiography. This reduction in left ventricular function was noted in patients with both normal and reduced right ventricular systolic functions by two-dimensional echocardiography.

Myocardial hypertrophy and function are related to age at onset in familial amyloidotic polyneuropathy

Heart complications are frequently encountered in hereditary transthyretin amyloidosis. Lately, reports of late onset familial amyloid polyneuropathy (FAP) cases presenting with a phenotype similar to that observed in senile systemic amyloidosis have emerged. The aim of the present study was to evaluate morphological and functional features of the heart by echocardiography including myocardial strain measurements, and to compare the outcome for early with those of late onset FAP cases. Eighty-one biopsy and genetically proven FAP, ATTR Val30Met patients were investigated with two-dimensional, M-mode echocardiography and myocardial strain with special attention to inter-ventricular septum (IVS) thickness. IVS thickness was closely related to the age at onset (P < 0.0001), but not to duration of disease. Seventeen percent of the patients had severe left ventricular hypertrophy (IVS > 15 mm). These patients were all late onset cases and represented 39% of all of the late onset cases. Strain measurements were also closely related to IVS thickness and age at onset thereby signifying a decreased function of the heart muscle in late onset cases. From the present investigation it appears that late onset Swedish FAP-cases more readily develop cardiomyopathy with an increased IVS thickness. Different pathways for amyloid formation in the heart may operate in early and late onset cases.

Elastic stiffness coefficients (c11, C33, and C13) for freshly excised and formalin-fixed myocardium from ultrasonic velocity measurements

The goal of this study was to measure elastic stiffness coefficients of freshly excised and subsequently formalin-fixed myocardial tissue. Our approach was to measure the angle-dependent phase velocities associated with the propagation of a longitudinal ultrasonic wave (3-8 MHz) in ovine myocardium using phase spectroscopy techniques and to interpret the results in the context of orthotropic and transversely isotropic models describing the elastic properties of myocardium. The phase velocity results together with density measurements were used to obtain the elastic stiffness coefficients c11, c33, and c13 for both symmetries. The results for the elastic stiffness coefficients c11, c33, and c13 are the same for both symmetries. Measurements for freshly excised myocardium and the same tissue after a period of formalin fixation were compared to examine the impact of fixation on the elastic stiffness coefficients.

Strain and strain rate imaging: a new clinical approach to quantifying regional myocardial function

On the basis of color Doppler myocardial motion data, 1-dimensional regional natural strain rate and strain curves can now be calculated by comparing local myocardial velocity profiles. Such deformation data sets may be an important, new, and more sensitive approach to quantifying both regional radial and long-axis function of the left or right ventricle in both acquired and congenital heart disease. The normal ranges of regional velocity, strain rate, and strain values have already been determined in both adults and children. This review will focus both on the potential clinical applications of these new ultrasound-based deformation parameters and the current limitations inherent in implementing the technique in everyday practice.