Assessment of myocardial mechanics in patients with end-stage renal disease and renal transplant recipients using speckle tracking echocardiography.

OBJECTIVES: Velocity vector imaging allows quantitation of myocardial strain and strain rate from 2-dimensional images based on speckle tracking echocardiography. The aim of this study was to analyze the changes in myocardial strain and strain rate patterns in patients with end-stage renal disease and renal transplant recipients. MATERIALS AND METHODS: We studied 33 patients with end-stage renal disease on hemodialysis (19 men; mean age, 36 ± 8 y), 24 renal transplant recipients with functional grafts (21 men; mean age, 36 ± 7 y) and 26 age- and sex-matched control subjects. Longitudinal peak systolic strain and strain rate for basal, mid, and apical segments of the left ventricular wall were determined by velocity vector imaging from apical 4- and 2-chamber views. The average longitudinal strain and strain rate for the left ventricle were noted. From short-axis views at the level of papillary muscles, average circumferential, and radial strain, and strain rate were assessed. RESULTS: Mean heart rate and systolic and diastolic blood pressure during imaging were similar between the groups. Longitudinal peak systolic strain and strain rate at basal and mid-segments of the lateral wall were significantly higher in renal transplant recipients and control groups than endstage renal disease patients. Average longitudinal systolic strain from the 4-chamber view was highest in control subjects (-14.5% ± 2.9%) and was higher in renal transplant recipients (-12.5% ± 3.0%) than end-stage renal disease patients (-10.2% ± 1.6%; P ≤ .001). Radial and circumferential strain and strain rate at the level of the papillary muscle were lower in patients with end-stage renal disease than other groups. CONCLUSIONS: Differences in myocardial function in patients with end-stage renal disease, renal transplant recipients, and normal controls can be quantified by strain imaging. Myocardial function is improved in renal transplant recipients compared with end-stage renal disease patients.

Dobutamine stress echocardiography in the assessment of cardiac allograft vasculopathy in asymptomatic recipients.

PURPOSE: Cardiac allograft vasculopathy (CAV) is the most important cause of late mortality among cardiac allograft recipients. Dobutamine stress echocardiography (DSE) is considered a safe and cost-effective method to screen these patients who remain free of angina most of the time. We evaluated DSE results in a series of cardiac allograft recipients. METHODS: The DSE was performed on a yearly basis. From 2004 to 2006, twelve DSEs were performed on 8 patients, including 7 men, and overall mean age of 36 +/- 12 years. Dobutamine infusion begun at 5 microg/kg/min was titrated at 3-minute stages to 10, 20, 40, and 50 microg/kg/min to achieve the target heart rate. In addition, at every stage, we performed a 12-lead EKG, heart rate, and blood pressure recording. The DSE results were compared with coronary angiograms and endomyocardial biopsies. RESULTS: Two patients displayed mildly and 1 patient a severely abnormal DSE test. The severely abnormal DSE test was associated with severe coronary artery stenosis, including inexperiment of the left main coronary artery. The second patient with an abnormal DSE had contour irregularities and distal cut-off of the right coronary artery as well as 2R cellular rejection. The third patient had a normal angiogram and no rejection. None of the patients with normal DSE experienced a cardiac event, coronary lesions, or rejection. CONCLUSION: Use of DSE appears to be a sensitive method to detect CAV in asymptomatic recipients. However, mild wall motion abnormalities can be detected in patients without stenosing coronary lesions. The value of DSE in predicting CAV must be examined in larger series with long-terms of follow-up.

Second-generation tissue Doppler with angle-corrected color-coded wall displacement for quantitative assessment of regional left ventricular function.

To test the hypothesis that a new tissue Doppler (TD) approach using angle-correction and transformation of velocity data to color-coded displacement data may objectively quantify regional left ventricular function, in vitro experiments were first performed with an oscillating echo target precisely controlled by a microstepping motor. Displacement varied from 1 to 15 mm (60 to 130 cycles/min) at angles of 0 degrees and 45 degrees to the echo transducer. Custom software transformed TD data to displacement data. Sixty-five subjects were then studied: 35 with wall motion abnormalities and 30 normal controls. Results were compared with independent visual assessment and caliper measurements of endocardial excursion from gray-scale images. In vitro displacement imaging strongly correlated with true displacement (r = 0.99, p <0.0001). In humans, peak transmural displacement discriminated normal results (6.3 +/- 3.2 mm) from hypokinesia (2.7 +/- 1.8 mm, p <0.05), akinesia (0.4 +/- 1.2 mm, p <0.05) from hypokinesia, and dyskinesia (-1.9 +/- 1.2 mm, p <0.05) from akinesia. Normal subendocardial displacement was 5.9 +/- 2.9 versus 4.0 +/- 3.9 mm in the epicardial layer (p <0.01). This displacement gradient was absent in abnormal segments. Displacement data correlated with endocardial excursion by calipers (parasternal views: r = 0.86, all views: r = 0.79, both p <0.0001). Overall accuracy of displacement imaging was 82% (kappa = 0.71) versus 66% (kappa = 0.43) for visual assessment with caliper data as the standard of reference. Angle-corrected displacement imaging was superior to routine visual assessment and is a promising new method to quantify regional left ventricular function.