Left ventricular transmural systolic function by high-sensitivity velocity measurement "phased-tracking method" across the septum in doxorubicin cardiomyopathy

Noninvasive early detection of anthracycline-induced cardiotoxicity in patients with hematologic malignancies using the phased tracking method

Anthracyclines are among the most effective and widely used anticancer drugs; however, their use is limited by serious cardiotoxicity. Early detection is necessary to prevent the high mortality rate associated with heart failure (HF). We evaluated cardiac function in 142 patients using conventional echocardiography and the phased tracking method (PTM), which was measured using the minute vibration and the rapid motion components, neither of which is recognized in standard M-mode nor in tissue Doppler imaging. For systolic function comparison, we compared left ventricular ejection fraction (LVEF) in conventional echocardiography with the average velocity of ventricular septum myocytes (Vave ) in the PTM. The Vave of 12 healthy volunteers was 1.5 (m/s)/m or more. At baseline of 99 patients, there was a positive correlation between LVEF and Vave in all patients. There were no significant differences in baseline cardiac function between patients with and without HF. There was a negative correlation between the cumulative anthracycline dose and LVEF or Vave among all patients. We determined that Vave 1.5 (m/s)/m was equivalent to LVEF 60%, 1.25 (m/s)/m to 55%, and 1.0 (m/s)/m to 50%. During the follow-up period, there was a pathological decrease in LVEF (<55%) and Vave (<1.25 m/s/m) in patients with HF; decreases in Vave were detected significantly earlier than those in LVEF (P < 0.001). When Vave declined to 1.5 (m/s)/m or less, careful continuous observation and cardiac examination was required. When Vave further declined to 1.0 (m/s)/m or lower, chemotherapy was postponed or discontinued; thus, serious drug-induced cardiomyopathy was avoided in patients who did not relapse. The PTM was superior to echocardiography for early, noninvasive detection and intermediate-term monitoring of left ventricle systolic function associated with anthracycline chemotherapy, among patients with hematologic malignancies. The PTM was an effective laboratory procedure to avoid the progression to serious cardiomyopathy.

Assessing Fetal Cardiac Function by Measuring Myocardial Radial Velocity Using the Phased-Tracking Method

OBJECTIVE

This study aimed to assess the cardiac function of healthy and pathological fetuses by measuring radial velocity using phased tracking (PT). Based on phase differences, PT allows the displacement of a specified point to be detected with improved spatial and temporal resolution.

METHODS

PT was used to assess cardiac radial velocity in the basal free wall of the left and right ventricles in 134 healthy fetuses, 10 second-trimester intrauterine growth-restricted (IUGR) fetuses, and 10 recipient twins with twin-to-twin transfusion syndrome (TTTS). Maximum velocities were measured in systole and early diastole.

RESULTS

Maximum radial velocity was successfully measured in 126 healthy fetuses (94%) at gestational ages of 16-40 weeks. Systolic and early diastolic maximum velocities increased with gestational age in both ventricles. As compared with controls, IUGR fetuses had significantly lower early diastolic maximum velocities in the right ventricle, and recipient twins with TTTS had significantly lower systolic and early diastolic maximum velocities in both ventricles.

CONCLUSIONS

PT demonstrated right ventricular diastolic dysfunction in second-trimester IUGR fetuses as well as systolic and diastolic dysfunctions in both ventricles in recipient twins with TTTS. PT could be useful for evaluating fetal cardiac radial function.

Ultrafast imaging in biomedical ultrasound

Although the use of ultrasonic plane-wave transmissions rather than line-per-line focused beam transmissions has been long studied in research, clinical application of this technology was only recently made possible through developments in graphical processing unit (GPU)-based platforms. Far beyond a technological breakthrough, the use of plane or diverging wave transmissions enables attainment of ultrafast frame rates (typically faster than 1000 frames per second) over a large field of view. This concept has also inspired the emergence of completely novel imaging modes which are valuable for ultrasound-based screening, diagnosis, and therapeutic monitoring. In this review article, we present the basic principles and implementation of ultrafast imaging. In particular, present and future applications of ultrafast imaging in biomedical ultrasound are illustrated and discussed.

Imaging of early modification in cardiomyopathy: the doxorubicin-induced model

Doxorubicin chemotherapy is effective and widely used to treat acute lymphoblastic leukemia. However, its effectiveness is hampered by a wide spectrum of dose-dependent cardiotoxicity including both morphological and functional changes, affecting primarily the myocardium. Non-invasive imaging techniques are used for the diagnosis and monitoring of these cardiotoxic effects. The purpose of this review is to summarize and compare the most common imaging techniques used in early detection and therapeutic monitoring of doxorubicin-induced cardiotoxicity and the suggested mechanisms of such side effects. Imaging techniques using echocardiography including conventional 2D and 3D echocardiography along with MRI sequences including Tagging, Cine, and quantitative MRI in detecting early myocardial damage are also reviewed. As there is a multitude of reported indices and imaging methods to assess particular functional alterations, we limit this review to the most relevant techniques based on their clinical application and their potential to early detection of doxorubicin-induced cardiotoxic effects.

Myocardial strain analysis in a doxorubicin-induced cardiomyopathy model

The aim of our study was to determine if strain (S) and strain rate (SR) imaging are more sensitive indices with respect to standard echocardiographic parameters to assess cardiac function in an experimental model of doxorubicin (DOX)-induced cardiomyopathy. DOX was administered intraperitoneally 4x/wk at the dose of 1.25 mg/kg/d over four weeks in Wistar rats (n = 26). Other 14 Wistar rats were used as controls. Echocardiographic studies were performed before DOX treatment (baseline), after two and four weeks of treatment. At two and four weeks of DOX treatment, rat hearts were collected for histologic analysis. After two weeks of DOX treatment, there were no significant changes in standard echocardiographic parameters and in myocardial velocities, but after four weeks of treatment, ejection fraction significantly decreased and left ventricle dimensions significantly increased. Also, myocardial velocities were significantly reduced after four weeks of treatment. Conversely, S and SR values changed significantly already after two weeks of treatment. At baseline, S and SR values were 27 +/- 7% and 7.4 +/- 1.7, respectively, and they significantly decreased to 12 +/- 6% (p < 0.0001) and 6 +/- 1.5 (p < 0.005) at two weeks of treatment. These changes were also significant compared with control rat parameters (p < 0.001). At four weeks of DOX treatment, a progressive worsening occurred. Strain and SR further significantly decreased to 10 +/- 4% (p < 0.0001 vs. baseline) and 4.6 +/- 1.6 (p < 0.0001 vs. baseline), respectively. These changes were supported by histologic findings. Indeed, damage in myocardial tissue was demonstrated by histology already after two weeks of DOX treatment, with a damage progression after four weeks of treatment. Our data demonstrate that S and SR imaging are more sensitive indices in identifying early myocardial systolic changes induced by DOX than standard echocardiographic parameters and myocardial velocities. We believe that our model will be very supportive to further assess these new diagnostic strategies to provide a precocious diagnosis of LV dysfunction with a unique opportunity to initiate preventive cardioactive therapy. (E-mail: giodisal@yahoo.it).

Fetal Myocardial Thickening Measured by Ultrasonic-Based Technique Called ‘Phased-Tracking Method’

OBJECTIVE

To evaluate fetal myocardial movement by using newly developed ultrasonic technique.

METHODS

We analyzed 50 normal fetuses between 25 and 41 weeks' gestation for changes in thickness of fetal myocardium using the phased-tracking method, a technique with high vertical distance resolution and the potential to evaluate fine ventricular wall movements. We analyzed differences in the rate of change in ventricular wall thickness and in changes in the inner and outer wall layers with advancing gestation. We also analyzed myocardial thickening period and evaluated the ratio of increasing thickness period to stroke interval.

RESULTS

Mean thickness changing rate was significantly higher in the right (1.18 +/- 0.34 m/s/m) than in the left ventricular wall (0.86 +/-0.31 m/s/m) (p < 0.001). Mean ratio of increasing thickness period to stroke interval was significantly higher in the right (0.57 +/- 0.064) than in the left ventricle (0.46 +/- 0.075) (p < 0.001), indicating that myocardial contraction in the fetal right ventricle predominates. The thickness-changing rate of the bilateral ventricular walls was positively and linearly correlated with gestational age. The myocardial-wall thickness-changing rate was higher in the outer layer than in the inner layer in late gestation.

CONCLUSIONS

We conclude that measurement of the thickness-changing rate of fetal ventricular walls using the phased-tracking method might be useful for evaluation of fetal cardiac function.