Regional variations of ultrasonic integrated backscatter in normal and myopathic left ventricles. A new multi-view approach.

The purpose of the present study was to determine whether the cyclic variation of integrated backscatter is measurable and quantifiable in all left ventricular walls and whether the information obtained using both parasternal and apical transducer positions can be used to identify changes in myocardial structure and contractility. The cyclic variation of integrated backscatter was measured from the parasternal long-axis, apical four-chamber and two-chamber views in 26 patients with idiopathic dilated cardiomyopathy (mean age 58 +/- 9 years; ejection fraction 29 +/- 10%) and compared with information obtained from 30 aged-matched healthy volunteers. For each subject, the cyclic variation of integrated backscatter was calculated from 16 predetermined regions-of-interest located within the myocardium of the basal and mid-segments of the left ventricle imaged from the long-axis view and also the basal mid and apical left ventricular segments imaged from the two apical views. The cyclic variation of integrated backscatter was found to be present in 100% of the analysed regions-of-interest in healthy volunteers and in 87.5% of the analysed regions-of-interest in patients with idiopathic dilated cardiomyopathy. The mean value of cyclic variation of integrated backscatter, averaged from all regions-of-interest in the idiopathic dilated cardiomyopathy group, was significantly reduced compared to that in the healthy volunteers group (3.2 +/- 2.5 dB [mean +/- SD] vs 4.8 +/- 2.9 dB, P < 0.0001). Additionally, the healthy volunteers group demonstrated marked regional variability in the magnitude of cyclic variation of integrated backscatter which closely followed the regional changes in the contractile function of the normal heart. These regional differences in the magnitude of the cyclic variation of integrated backscatter were only partially retained in the idiopathic dilated cardiomyopathy group, and suggest that a multi-view approach of the recording of cyclic variation of integrated backscatter can be of value to differentiate normal from myopathic myocardium and to quantify regional differences in myocardial contractile performance throughout the left ventricular walls.

Detection of myocardial viability in the prediction of improvement in left ventricular function after successful coronary revascularization by using the dobutamine stress echocardiography and quantitative SPECT rest-redistribution-reinjection 201TI imaging after dipyridamole infusion.

The aim of this study was to assess the feasibility, safety, and respective diagnostic accuracy of low-dose dobutamine infusion and rest-redistribution-reinjection thallium 201 single photon emission computed tomography (SPECT) after dipyridamole infusion (Th-DIP), in the prediction of functional improvement of asynergic infarcted zones, after successful revascularization in patients with chronic ischemic heart disease. Thirty-one patients with a previous myocardial infarction and left ventricular dysfunction (mean ejection fraction: 41 +/- 5.8%) were studied. The regional wall motion of the left ventricle was evaluated by basic echocardiography before and 14 +/- 1.7 weeks after successful revascularization (19 by percutaneous transluminal coronary angioplasty and 12 by coronary artery bypass grafting). Dobutamine stress echocardiography (DSE) was performed in all patients with dobutamine infusion of 5 and 10 micrograms/kg/minute over five minutes. Within three days after DSE and prior to revascularization, all patients underwent Th-DIP for myocardial viability assessment. A 16-ventricular-segment model was used for basic, DSE, and Th-DIP images. Viability was assessed by applying the standard criteria for each technique. In the 31 patients, 496 segments were analyzed. By basic echocardiography, 164 (33%) of them were classified as asynergic. The DSE detected viable tissue in 69/496 (14%) segments, whereas Th-DIP identified viability in 95/496 (19%) segments. When the postrevascularization basic echocardiographic study was used as the gold standard in identifying myocardial viability, the sensitivity and specificity for the DSE and Th-DIP were 86.5%, 94.4% and 90.5%, 69%, respectively. No major side effects were observed with both techniques. In conclusion, DSE seems to be an accurate method for identifying viable but asynergic myocardium in patients with chronic ischemic heart disease, whereas Th-DIP overestimates the postrevascularization recovery. Detection of hibernating myocardium can be obtained by these two noninvasive methods. However, DSE seems to be more useful in determining the prospective selection of patients who are going to benefit from revascularization.

Age-related transmural peak mean velocities and peak velocity gradients by Doppler myocardial imaging in normal subjects.

Doppler myocardial imaging is a new cardiac ultrasound technique based on the principles of colour Doppler imaging which can determine myocardial velocities by detecting the changes of phase-shift of the ultrasound signal returning directly from the myocardium. To determine the normal range of transmural velocities in healthy hearts a prospective study was carried out involving 42 normal subjects (age from 21 to 78, mean 47 +/- 16 years). Using M-mode Doppler myocardial imaging the peak values of the mean velocity and velocity gradient across the left ventricular posterior wall were measured during standardized phases of the cardiac cycle. Peak mean velocities had the following values during the cardiac cycle: isovolumic contraction - 1.3 +/- 1.2 cm. s-1, early ventricular ejection 4.2 +/- 1.2 cm. s-1, late ventricular ejection 1.8 +/- 1.1 cm. s-1, isovolumic relaxation -2.0 +/- 0.8 cm. s-1, rapid ventricular filling -6.6 +/- 2.2 cm. s-1, atrial contraction -2.8 +/- 1.8 cm. s-1, atrial relaxation 1.2 +/- 1.1 cm. s-1. Peak velocity gradients were: isovolumic contraction 1.3 +/- 1.9 s-1, early ventricular contraction 4.7 +/- 1.9 s-1, late ventricular contraction 1.1 +/- 1.0 s-1, isovolumic relaxation -0.6 +/- 0.5 s-1, rapid ventricular filling 6.1 +/- 3.4 s-1, atrial contraction 2.6 +/- 1.7 s-1, atrial relaxation 0.0 +/- 0.3 s-1. Linear regression analysis showed that with the increase of age, peak velocity gradient decreases during rapid ventricular filling (r = 0.83; P < 0.0001) and increases during atrial contraction (r = 0.86; P < 0.0001) while peak mean velocity increases only during atrial contraction (r = 0.80, P < 0.0001). Thus, there was no correlation between increasing age and systolic peak mean velocity and peak velocity gradient but both diastolic filling phases rapid ventricular filling and atrial contraction demonstrated age-related changes. In summary, this study has determined the age-related range of normal transmural myocardial velocities within the left ventricular posterior wall in healthy hearts during the cardiac cycle. We conclude that these measurements of peak mean velocities and peak velocity gradients, should form the baseline for subsequent Doppler myocardial imaging clinical studies on myocardial diseases processes.